Science.gov

Sample records for agn fraction increases

  1. Does the obscured AGN fraction really depend on luminosity?

    NASA Astrophysics Data System (ADS)

    Sazonov, S.; Churazov, E.; Krivonos, R.

    2015-12-01

    We use a sample of 151 local non-blazar active galactic nuclei (AGN) selected from the INTEGRAL all-sky hard X-ray survey to investigate if the observed declining trend of the fraction of obscured (i.e. showing X-ray absorption) AGN with increasing luminosity is mostly an intrinsic or selection effect. Using a torus-obscuration model, we demonstrate that in addition to negative bias, due to absorption in the torus, in finding obscured AGN in hard X-ray flux-limited surveys, there is also positive bias in finding unobscured AGN, due to Compton reflection in the torus. These biases can be even stronger taking into account plausible intrinsic collimation of hard X-ray emission along the axis of the obscuring torus. Given the AGN luminosity function, which steepens at high luminosities, these observational biases lead to a decreasing observed fraction of obscured AGN with increasing luminosity even if this fraction has no intrinsic luminosity dependence. We find that if the central hard X-ray source in AGN is isotropic, the intrinsic (i.e. corrected for biases) obscured AGN fraction still shows a declining trend with luminosity, although the intrinsic obscured fraction is significantly larger than the observed one: the actual fraction is larger than ˜85 per cent at L ≲ 1042.5 erg s-1 (17-60 keV), and decreases to ≲60 per cent at L ≳ 1044 erg s-1. In terms of the half-opening angle θ of an obscuring torus, this implies that θ ≲ 30° in lower luminosity AGN, and θ ≳ 45° in higher luminosity ones. If, however, the emission from the central supermassive black hole is collimated as dL/dΩ ∝ cos α, the intrinsic dependence of the obscured AGN fraction is consistent with a luminosity-independent torus half-opening angle θ ˜ 30°.

  2. An enhanced fraction of starbursting galaxies among high Eddington ratio AGNs

    NASA Astrophysics Data System (ADS)

    Bernhard, E.; Mullaney, J. R.; Daddi, E.; Ciesla, L.; Schreiber, C.

    2016-04-01

    We investigate the star-forming properties of 1620 X-ray selected AGN host galaxies as a function of their specific X-ray luminosity (i.e., X-ray luminosity per unit host stellar mass) - a proxy of the Eddington ratio. Our motivation is to determine whether there is any evidence of a suppression of star-formation at high Eddington ratios, which may hint toward "AGN feedback" effects. Star-formation rates (SFRs) are derived from fits to Herschel-measured far-infrared spectral energy distributions, taking into account any contamination from the AGN. Herschel-undetected AGNs are included via stacking analyses to provide average SFRs in bins of redshift and specific X-ray luminosity (spanning 0.01 ≲ L_X/M_{ast } ≲ 100 L_{⊙} M_{⊙}^{-1}). After normalising for the effects of mass and redshift arising from the evolving galaxy main sequence, we find that the SFRs of high specific luminosity AGNs are slightly enhanced compared to their lower specific luminosity counterparts. This suggests that the SFR distribution of AGN hosts changes with specific X-ray luminosity, a result reinforced by our finding of a significantly higher fraction of starbursting hosts among high specific luminosity AGNs compared to that of the general star-forming galaxy population (i.e., 8-10 per cent vs. 3 per cent). Contrary to our original motivation, our findings suggest that high specific luminosity AGNs are more likely to reside in galaxies with enhanced levels of star-formation.

  3. An enhanced fraction of starbursting galaxies among high Eddington ratio AGNs

    NASA Astrophysics Data System (ADS)

    Bernhard, E.; Mullaney, J. R.; Daddi, E.; Ciesla, L.; Schreiber, C.

    2016-07-01

    We investigate the star-forming properties of 1620 X-ray selected active galactic nuclei (AGN) host galaxies as a function of their specific X-ray luminosity (i.e. X-ray luminosity per unit host stellar mass) - a proxy of the Eddington ratio. Our motivation is to determine whether there is any evidence of a suppression of star formation at high Eddington ratios, which may hint towards `AGN feedback' effects. Star formation rates (SFRs) are derived from fits to Herschel-measured far-infrared spectral energy distributions, taking into account any contamination from the AGN. Herschel-undetected AGNs are included via stacking analyses to provide average SFRs in bins of redshift and specific X-ray luminosity (spanning 0.01 ≲ L_X/M_{ast } ≲ 100 L_{{⊙}} M_{{⊙}}^{-1}). After normalizing for the effects of mass and redshift arising from the evolving galaxy main sequence, we find that the SFRs of high specific luminosity AGNs are slightly enhanced compared to their lower specific luminosity counterparts. This suggests that the SFR distribution of AGN hosts changes with specific X-ray luminosity, a result reinforced by our finding of a significantly higher fraction of starbursting hosts among high specific luminosity AGNs compared to that of the general star-forming galaxy population (i.e. 8-10 per cent versus 3 per cent). Contrary to our original motivation, our findings suggest that high specific luminosity AGNs are more likely to reside in galaxies with enhanced levels of star formation.

  4. The role of stellar mass and environment for cluster blue fraction, AGN fraction and star formation indicators from a targeted analysis of Abell 1691

    NASA Astrophysics Data System (ADS)

    Pimbblet, Kevin A.; Jensen, Peter C.

    2012-10-01

    We present an analysis of the galaxy population of the intermediate X-ray luminosity galaxy cluster, Abell 1691, from Sloan Digital Sky Survey (SDSS) and Galaxy Zoo data to elucidate the relationships between environment and galaxy stellar mass for a variety of observationally important cluster populations that include the Butcher-Oemler blue fraction, the active galactic nucleus (AGN) fraction and other spectroscopic classifications of galaxies. From 342 cluster members, we determine a cluster recession velocity of 21257 ± 54 km s-1 and velocity dispersion of 1009-36+40 km s-1 and show that although the cluster is fed by multiple filaments of galaxies it does not possess significant sub-structure in its core. We identify the AGN population of the cluster from a Baldwin, Phillips & Terlevich diagram and show that there is a mild increase in the AGN fraction with radius from the cluster centre that appears mainly driven by high-mass galaxies [log(stellar mass) > 10.8]. Although the cluster blue fraction follows the same radial trend, it is caused primarily by lower mass galaxies [log(stellar mass) < 10.8]. Significantly, the galaxies that have undergone recent starbursts or are presently starbursting but dust-shrouded [spectroscopic e(a) class galaxies] are also nearly exclusively driven by low-mass galaxies. We therefore suggest that the Butcher-Oemler effect may be a mass-dependent effect. We also examine red and passive spiral galaxies and show that the majority are massive galaxies, much like the rest of the red and spectroscopically passive cluster population. We further demonstrate that the velocity dispersion profiles of low- and high-mass cluster galaxies are different. Taken together, we infer that the duty cycle of high- and low-mass cluster galaxies is markedly different, with a significant departure in star formation and specific star formation rates observed beyond r200 and we discuss these findings.

  5. A Chandra-Swift View of Point Sources in Hickson Compact Groups: High AGN Fraction but a Dearth of Strong AGNs

    NASA Technical Reports Server (NTRS)

    Tzanavaris, P.; Gallagher, S. C.; Hornschemeier, A. E.; Fedotov, K.; Eracleous, M.; Brandt, W. N.; Desjardins, T. D.; Charlton, J. C.; Gronwall, C.

    2014-01-01

    We present Chandra X-ray point source catalogs for 9 Hickson Compact Groups (HCGs, 37 galaxies) at distances of 34-89 Mpc. We perform detailed X-ray point source detection and photometry and interpret the point source population by means of simulated hardness ratios. We thus estimate X-ray luminosities (L(sub x)) for all sources, most of which are too weak for reliable spectral fitting. For all sources, we provide catalogs with counts, count rates, power-law indices (gamma), hardness ratios, and L(sub X), in the full (0.5-8.0 keV), soft (0.5-2.0 keV), and hard (2.0-8.0 keV) bands. We use optical emission-line ratios from the literature to re-classify 24 galaxies as star-forming, accreting onto a supermassive black hole (AGNs), transition objects, or low-ionization nuclear emission regions. Two-thirds of our galaxies have nuclear X-ray sources with Swift/UVOT counterparts. Two nuclei have L(sub X),0.5-8.0 keV > 10(exp 42) erg s-1, are strong multi-wavelength active galactic nuclei (AGNs), and follow the known alpha OX-?L? (nearUV) correlation for strong AGNs. Otherwise, most nuclei are X-ray faint, consistent with either a low-luminosity AGN or a nuclear X-ray binary population, and fall in the 'non-AGN locus' in alpha OX-?L? (nearUV) space, which also hosts other normal galaxies. Our results suggest that HCG X-ray nuclei in high specific star formation rate spiral galaxies are likely dominated by star formation, while those with low specific star formation rates in earlier types likely harbor a weak AGN. The AGN fraction in HCG galaxies with MR (is) less than -20 and L(sub X),0.5-8.0 keV (is) greater than 10(exp 41) erg s-1 is 0.08+0.35 -0.01, somewhat higher than the 5% fraction in galaxy clusters.

  6. A Chandra-Swift View of Point Sources in Hickson Compact Groups: High AGN Fraction but a Dearth of Strong AGNs

    NASA Astrophysics Data System (ADS)

    Tzanavaris, P.; Gallagher, S. C.; Hornschemeier, A. E.; Fedotov, K.; Eracleous, M.; Brandt, W. N.; Desjardins, T. D.; Charlton, J. C.; Gronwall, C.

    2014-05-01

    We present Chandra X-ray point source catalogs for 9 Hickson Compact Groups (HCGs, 37 galaxies) at distances of 34-89 Mpc. We perform detailed X-ray point source detection and photometry and interpret the point source population by means of simulated hardness ratios. We thus estimate X-ray luminosities (LX ) for all sources, most of which are too weak for reliable spectral fitting. For all sources, we provide catalogs with counts, count rates, power-law indices (Γ), hardness ratios, and LX , in the full (0.5-8.0 keV), soft (0.5-2.0 keV), and hard (2.0-8.0 keV) bands. We use optical emission-line ratios from the literature to re-classify 24 galaxies as star-forming, accreting onto a supermassive black hole (AGNs), transition objects, or low-ionization nuclear emission regions. Two-thirds of our galaxies have nuclear X-ray sources with Swift/UVOT counterparts. Two nuclei have L X, 0.5-8.0 keV >1042 erg s-1, are strong multi-wavelength active galactic nuclei (AGNs), and follow the known αOX-νL ν (nearUV) correlation for strong AGNs. Otherwise, most nuclei are X-ray faint, consistent with either a low-luminosity AGN or a nuclear X-ray binary population, and fall in the "non-AGN locus" in αOX-νL ν (nearUV) space, which also hosts other normal galaxies. Our results suggest that HCG X-ray nuclei in high specific star formation rate spiral galaxies are likely dominated by star formation, while those with low specific star formation rates in earlier types likely harbor a weak AGN. The AGN fraction in HCG galaxies with MR <= -20 and L X, 0.5-8.0 keV >=1041 erg s-1 is 0.08^{+0.35}_{-0.01}, somewhat higher than the ~5% fraction in galaxy clusters.

  7. Obscured AGN

    NASA Astrophysics Data System (ADS)

    Barger, Amy

    2014-07-01

    Obscured AGN may correspond to a substantial fraction of the supermassive black hole growth rate. I will present new surveys with the SCUBA-2 instrument on the James Clerk Maxwell Telescope of the Chandra Deep Fields and discuss whether we can distinguish obscured AGN in hard X-ray and radio selected samples using submillimeter observations.

  8. A method for determining AGN accretion phase in field galaxies

    NASA Astrophysics Data System (ADS)

    Micic, Miroslav; Martinović, Nemanja; Sinha, Manodeep

    2016-09-01

    Recent observations of active galactic nucleus (AGN) activity in massive galaxies (log M*/ M⊙ > 10.4) show the following: (1) at z < 1, AGN-hosting galaxies do not show enhanced merger signatures compared with normal galaxies, (2) also at z < 1, most AGNs are hosted by quiescent galaxies and (3) at z > 1, the percentage of AGNs in star-forming galaxies increases and becomes comparable to the AGN percentage in quiescent galaxies at z ˜ 2. How can major mergers explain AGN activity in massive quiescent galaxies that have no merger features and no star formation to indicate a recent galaxy merger? By matching merger events in a cosmological N-body simulation to the observed AGN incidence probability in the COSMOS survey, we show that major merger-triggered AGN activity is consistent with the observations. By distinguishing between `peak' AGNs (recently merger-triggered and hosted by star-forming galaxies) and `faded' AGNs (merger-triggered a long time ago and now residing in quiescent galaxies), we show that the AGN occupation fraction in star-forming and quiescent galaxies simply follows the evolution of the galaxy merger rate. Since the galaxy merger rate drops dramatically at z < 1, the only AGNs left to be observed are the ones triggered by old mergers that are now in the declining phase of their nuclear activity, hosted by quiescent galaxies. As we go towards higher redshifts, the galaxy merger rate increases and the percentages of `peak' AGNs and `faded' AGNs become comparable.

  9. THE GALACTIC SPIN OF AGN GALAXIES

    SciTech Connect

    Cervantes-Sodi, Bernardo; Hernandez, X.; Park, Changbom; Choi, Yun-Young E-mail: xavier@astroscu.unam.mx

    2011-07-01

    Using an extensive sample of galaxies selected from the Sloan Digital Sky Survey Data Release 5, we compare the angular momentum distribution of active galactic nuclei (AGNs) with non-AGN hosting late-type galaxies. To this end we characterize galactic spin through the dimensionless angular momentum parameter {lambda}, which we estimate through simple dynamical considerations. Using a volume-limited sample, we find a considerable difference when comparing the empirical distributions of {lambda} for AGNs and non-AGN galaxies, the AGNs showing typically low {lambda} values and associated dispersions, while non-AGNs present higher {lambda} values and a broader distribution. A more striking difference is found when looking at {lambda} distributions in thin M{sub r} cuts; while the spin of non-AGN galaxies presents an anticorrelation with M{sub r} , with bright (massive) galaxies having low spins, AGN host galaxies present uniform values of {lambda} at all magnitudes, a behavior probably imposed by the fact that most late-type AGN galaxies present a narrow range in color, with a typical constant {lambda} value. We also find that the fraction of AGN hosting galaxies in our sample strongly depends on galactic spin, increasing dramatically for decreasing {lambda}. For AGN host galaxies, we compute the mass of their supermassive black holes and find that this value tends to be higher for low spin galaxies, even at fixed luminosity, a result that could account, to a certain extent, for the spread on the luminosity-black-hole mass relation.

  10. A New Catalog of Type 1 AGNs and its Implications on the AGN Unified Model

    NASA Astrophysics Data System (ADS)

    Oh, Kyuseok; Yi, Sukyoung K.; Schawinski, Kevin; Koss, Michael; Trakhtenbrot, Benny; Soto, Kurt

    2015-07-01

    We have recently identified a substantial number of type 1 active galactic nuclei (AGNs) featuring weak broad-line regions (BLRs) at z\\lt 0.2 from detailed analysis of galaxy spectra in the Sloan Digital Sky Survey Data Release 7. These objects predominantly show a stellar continuum but also a broad Hα emission line, indicating the presence of a low-luminosity AGN oriented so that we are viewing the central engine directly without significant obscuration. These accreting black holes have previously eluded detection due to their weak nature. The newly discovered BLR AGNs have increased the number of known type 1 AGNs by 49%. Some of these new BLR AGNs were detected with the Chandra X-ray Observatory, and their X-ray properties confirm that they are indeed type 1 AGNs. Based on our new and more complete catalog of type 1 AGNs, we derived the type 1 fraction of AGNs as a function of [O iii] λ 5007 emission luminosity and explored the possible dilution effect on obscured AGNs due to star formation. The new type 1 AGN fraction shows much more complex behavior with respect to black hole mass and bolometric luminosity than has been suggested previously by the existing receding torus model. The type 1 AGN fraction is sensitive to both of these factors, and there seems to be a sweet spot (ridge) in the diagram of black hole mass and bolometric luminosity. Furthermore, we present the possibility that the Eddington ratio plays a role in determining opening angles.

  11. Fermentation and dry fractionation increase bioactivity of cloudberry (Rubus chamaemorus).

    PubMed

    Puupponen-Pimiä, Riitta; Nohynek, Liisa; Juvonen, Riikka; Kössö, Tuija; Truchado, Pilar; Westerlund-Wikström, Benita; Leppänen, Tiina; Moilanen, Eeva; Oksman-Caldentey, Kirsi-Marja

    2016-04-15

    Phenolic composition and bioactivity of cloudberry was modified by bioprocessing, and highly bioactive fractions were produced by dry fractionation of the press cake. During fermentation polymeric ellagitannins were partly degraded into ellagic acid derivatives. Phenolic compounds were differentially distributed in seed coarse and fine fractions after dry fractionation process. Tannins concentrated in fine fraction, and flavonol derivatives were mainly found in coarse fraction. Ellagic acid derivatives were equally distributed between the dry fractions. Fermentation and dry fractionation increased statistically significantly anti-adhesion and anti-inflammatory activity of cloudberry. The seed fine fraction showed significant inhibition of P fimbria-mediated haemagglutination assay of uropathogenic Escherichia coli. The seed coarse fraction significantly reduced NO and IL-6 production and iNOS expression in activated macrophages. Fermentation did not affect antimicrobial activity, but slight increase in activity was detected in dry fractions. The results indicate the potential of cloudberry in pharma or health food applications. PMID:26617039

  12. Galaxy Zoo: AGN may be fueled by stellar bars in the local Universe

    NASA Astrophysics Data System (ADS)

    Galloway, Melanie; Willett, Kyle; Fortson, Lucy; Galaxy Zoo Science Team

    2015-01-01

    Bars are a mechanism that have been proposed to explain how gas in the outer regions of a galaxy can be channeled inward and fuel AGN. Multiple observational studies have reported a significantly higher bar fraction in AGN than non-AGN. To accurately probe whether an excess of bars in AGN host galaxies exists because the galaxies host a bar, it is necessary to compare bar and AGN fractions at fixed mass and color, because the presence of bars strongly correlates with both. Thus, a sufficiently large sample is necessary to maintain adequate numbers in subsets of fixed mass and color. We have created a large, volume-limited sample of 19,765 disc galaxies using data from the Sloan Digital Sky Survey. By using morphological classifications from the Galaxy Zoo 2 project, we identify stellar bars in 51.8% of AGN hosts and 37.1% of star-forming disk galaxies. Once mass and color are fixed, there remains a statistically significant increase in the fraction of barred AGN over their unbarred counterparts. Using the L[O III]/MBH ratio as a measure of accretion efficiency, we also show that barred AGN do not exhibit stronger accretion than unbarred AGN at fixed mass or color. The data are consistent with a model in which bar-driven fueling does contribute to the probability of an actively growing black hole, but in which other dynamical mechanisms must contribute to AGN fueling via smaller, non-axisymmetric perturbations.

  13. Signatures of AGN feedback

    NASA Astrophysics Data System (ADS)

    Wylezalek, D.; Zakamska, N.

    2016-06-01

    Feedback from active galactic nuclei (AGN) is widely considered to be the main driver in regulating the growth of massive galaxies. It operates by either heating or driving the gas that would otherwise be available for star formation out of the galaxy, preventing further increase in stellar mass. Observational proof for this scenario has, however, been hard to come by. We have assembled a large sample of 133 radio-quiet type-2 and red AGN at 0.1AGN-ionized gas, the stellar masses of the host galaxies and their star formation rates. We then investigate the relationships between AGN luminosities, specific star formation rates (sSFR) and outflow strengths W_{90} - the 90% velocity width of the [OIII]λ5007Å line power and a proxy for the AGN-driven outflow speed. Outflow strength W_{90} is independent of sSFR for AGN selected based on their mid-IR luminosity. This is in agreement with previous work that demonstrates that star formation is not sufficient to produce the observed ionized gas outflows which have to be powered by AGN activity. More importantly, we find a negative correlation between W_{90} and sSFR in the AGN hosts with the highest star formation rates, i.e., with the highest gas content. This relationship implies that AGN with strong outflow signatures are hosted in galaxies that are more `quenched' considering their stellar mass than galaxies with weaker outflow signatures. This correlation is only seen in AGN host galaxies with SFR >100 M_{⊙} yr^{-1} where presumably the coupling of the AGN-driven wind to the gas is strongest. This observation is consistent with the AGN having a net suppression, or `negative' impact, through feedback on the galaxies' star formation history.

  14. Spectral decomposition of broad-line agns and host galaxies

    SciTech Connect

    Vanden Berk, Daniel E.; Shen, Jiajian; Yip, Ching-Wa; Schneider, Donald P.; Connolly, Andrew J.; Burton, Ross E.; Jester, Sebastian; Hall, Patrick B.; Szalay, Alex S.; Brinkmann, John; /Apache Point Observ.

    2005-09-01

    Using an eigenspectrum decomposition technique, we separate the host galaxy from the broad line active galactic nucleus (AGN) in a set of 4666 spectra from the Sloan Digital Sky Survey (SDSS), from redshifts near zero up to about 0.75. The decomposition technique uses separate sets of galaxy and quasar eigenspectra to efficiently and reliably separate the AGN and host spectroscopic components. The technique accurately reproduces the host galaxy spectrum, its contributing fraction, and its classification. We show how the accuracy of the decomposition depends upon S/N, host galaxy fraction, and the galaxy class. Based on the eigencoefficients, the sample of SDSS broad-line AGN host galaxies spans a wide range of spectral types, but the distribution differs significantly from inactive galaxies. In particular, post-starburst activity appears to be much more common among AGN host galaxies. The luminosities of the hosts are much higher than expected for normal early-type galaxies, and their colors become increasingly bluer than early-type galaxies with increasing host luminosity. Most of the AGNs with detected hosts are emitting at between 1% and 10% of their estimated Eddington luminosities, but the sensitivity of the technique usually does not extend to the Eddington limit. There are mild correlations among the AGN and host galaxy eigencoefficients, possibly indicating a link between recent star formation and the onset of AGN activity. The catalog of spectral reconstruction parameters is available as an electronic table.

  15. Are Compton-thick AGNs the Missing Link between Mergers and Black Hole Growth?

    NASA Astrophysics Data System (ADS)

    Kocevski, Dale D.; Brightman, Murray; Nandra, Kirpal; Koekemoer, Anton M.; Salvato, Mara; Aird, James; Bell, Eric F.; Hsu, Li-Ting; Kartaltepe, Jeyhan S.; Koo, David C.; Lotz, Jennifer M.; McIntosh, Daniel H.; Mozena, Mark; Rosario, David; Trump, Jonathan R.

    2015-12-01

    We examine the host morphologies of heavily obscured active galactic nuclei (AGNs) at z∼ 1 to test whether obscured super-massive black hole growth at this epoch is preferentially linked to galaxy mergers. Our sample consists of 154 obscured AGNs with {N}{{H}}\\gt {10}23.5 {{cm}}-2 and z\\lt 1.5. Using visual classifications, we compare the morphologies of these AGNs to control samples of moderately obscured (1022 cm{}-2\\lt {N}{{H}}\\lt {10}23.5 {{cm}}-2) and unobscured ({N}{{H}}\\lt {10}22 {{cm}}-2) AGN. These control AGNs have similar redshifts and intrinsic X-ray luminosities to our heavily obscured AGN. We find that heavily obscured AGNs are twice as likely to be hosted by late-type galaxies relative to unobscured AGNs ({65.3}-4.6+4.1% versus {34.5}-2.7+2.9%) and three times as likely to exhibit merger or interaction signatures ({21.5}-3.3+4.2% versus {7.8}-1.3+1.9%). The increased merger fraction is significant at the 3.8σ level. If we exclude all point sources and consider only extended hosts, we find that the correlation between the merger fraction and obscuration is still evident, although at a reduced statistical significance (2.5σ ). The fact that we observe a different disk/spheroid fraction versus obscuration indicates that the viewing angle cannot be the only thing differentiating our three AGN samples, as a simple unification model would suggest. The increased fraction of disturbed morphologies with obscuration supports an evolutionary scenario, in which Compton-thick AGNs are a distinct phase of obscured super-massive black hole (SMBH) growth following a merger/interaction event. Our findings also suggest that some of the merger-triggered SMBH growth predicted by recent AGN fueling models may be hidden among the heavily obscured, Compton-thick population.

  16. PRIMUS: INFRARED AND X-RAY AGN SELECTION TECHNIQUES AT 0.2 < z < 1.2

    SciTech Connect

    Mendez, Alexander J.; Coil, Alison L.; Aird, James; Diamond-Stanic, Aleksandar M.; Moustakas, John; Blanton, Michael R.; Cool, Richard J.; Eisenstein, Daniel J.; Wong, Kenneth C.; Zhu Guangtun

    2013-06-10

    We present a study of Spitzer/IRAC and X-ray active galactic nucleus (AGN) selection techniques in order to quantify the overlap, uniqueness, contamination, and completeness of each. We investigate how the overlap and possible contamination of the samples depend on the depth of both the IR and X-ray data. We use Spitzer/IRAC imaging, Chandra and XMM-Newton X-ray imaging, and spectroscopic redshifts from the PRism MUlti-object Survey to construct galaxy and AGN samples at 0.2 < z < 1.2 over 8 deg{sup 2}. We construct samples over a wide range of IRAC flux limits (SWIRE to GOODS depth) and X-ray flux limits (10 ks to 2 Ms). We compare IR-AGN samples defined using both the IRAC color selection of Stern et al. and Donley et al. with X-ray-detected AGN samples. For roughly similar depth IR and X-ray surveys, we find that {approx}75% of IR-selected AGNs are also identified as X-ray AGNs. This fraction increases to {approx}90% when comparing against the deepest X-ray data, indicating that at most {approx}10% of IR-selected AGNs may be heavily obscured. The IR-AGN selection proposed by Stern et al. suffers from contamination by star-forming galaxies at various redshifts when using deeper IR data, though the selection technique works well for shallow IR data. While similar overall, the IR-AGN samples preferentially contain more luminous AGNs, while the X-ray AGN samples identify a wider range of AGN accretion rates including low specific accretion rate AGNs, where the host galaxy light dominates at IR wavelengths. The host galaxy populations of the IR and X-ray AGN samples have similar rest-frame colors and stellar masses; both selections identify AGNs in blue, star-forming and red, quiescent galaxies.

  17. PRIMUS: Infrared and X-Ray AGN Selection Techniques at 0.2 < z < 1.2

    NASA Astrophysics Data System (ADS)

    Mendez, Alexander J.; Coil, Alison L.; Aird, James; Diamond-Stanic, Aleksandar M.; Moustakas, John; Blanton, Michael R.; Cool, Richard J.; Eisenstein, Daniel J.; Wong, Kenneth C.; Zhu, Guangtun

    2013-06-01

    We present a study of Spitzer/IRAC and X-ray active galactic nucleus (AGN) selection techniques in order to quantify the overlap, uniqueness, contamination, and completeness of each. We investigate how the overlap and possible contamination of the samples depend on the depth of both the IR and X-ray data. We use Spitzer/IRAC imaging, Chandra and XMM-Newton X-ray imaging, and spectroscopic redshifts from the PRism MUlti-object Survey to construct galaxy and AGN samples at 0.2 < z < 1.2 over 8 deg2. We construct samples over a wide range of IRAC flux limits (SWIRE to GOODS depth) and X-ray flux limits (10 ks to 2 Ms). We compare IR-AGN samples defined using both the IRAC color selection of Stern et al. and Donley et al. with X-ray-detected AGN samples. For roughly similar depth IR and X-ray surveys, we find that ~75% of IR-selected AGNs are also identified as X-ray AGNs. This fraction increases to ~90% when comparing against the deepest X-ray data, indicating that at most ~10% of IR-selected AGNs may be heavily obscured. The IR-AGN selection proposed by Stern et al. suffers from contamination by star-forming galaxies at various redshifts when using deeper IR data, though the selection technique works well for shallow IR data. While similar overall, the IR-AGN samples preferentially contain more luminous AGNs, while the X-ray AGN samples identify a wider range of AGN accretion rates including low specific accretion rate AGNs, where the host galaxy light dominates at IR wavelengths. The host galaxy populations of the IR and X-ray AGN samples have similar rest-frame colors and stellar masses; both selections identify AGNs in blue, star-forming and red, quiescent galaxies.

  18. The Spitzer Mid-infrared AGN Survey. II. The Demographics and Cosmic Evolution of the AGN Population

    NASA Astrophysics Data System (ADS)

    Lacy, M.; Ridgway, S. E.; Sajina, A.; Petric, A. O.; Gates, E. L.; Urrutia, T.; Storrie-Lombardi, L. J.

    2015-04-01

    We present luminosity functions derived from a spectroscopic survey of active galactic nuclei (AGNs) selected from Spitzer Space Telescope imaging surveys. Selection in the mid-infrared is significantly less affected by dust obscuration. We can thus compare the luminosity functions of obscured and unobscured AGNs in a more reliable fashion than by using optical or X-ray data alone. We find that the AGN luminosity function can be well described by a broken power-law model in which the break luminosity decreases with redshift. At high redshifts (z\\gt 1.6), we find significantly more AGNs at a given bolometric luminosity than found by either optical quasar surveys or hard X-ray surveys. The fraction of obscured AGNs decreases rapidly with increasing AGN luminosity, but, at least at high redshifts, appears to remain at ≈ 50% even at bolometric luminosities ˜ {{10}14} {{L}⊙ }. The data support a picture in which the obscured and unobscured populations evolve differently, with some evidence that high luminosity obscured quasars peak in space density at a higher redshift than their unobscured counterparts. The amount of accretion energy in the universe estimated from this work suggests that AGNs contribute about 12% to the total radiation intensity of the universe, and a high radiative accretion efficiency ≈ 0.18-0.07+0.12 is required to match current estimates of the local mass density in black holes.

  19. Team work increases fractionation capacity cost-effectively

    SciTech Connect

    Talib, J.H.; Germinder, B.; Hitchcock, M.P.

    1997-10-01

    During the early stages of the Discovery project in 1996, Texaco-Bridgeline Gas Distribution LLC planned on refurbishing an existing mothballed four-column fractionation facility at Paradis, Louisiana. The goal was to process Y-grade feed from a new 600 MMscfd cryogenic gas processing plant at Larose, Louisiana, and from the existing cryogenic facilities at Paradis. The Paradis debottlenecking team (PDT) met its goals by identifying and removing obvious process bottlenecks, minimizing costs and eliminating schedule impact, while increasing the Paradis facility fractionation capacity from 34,000 bpd to 42,000 bpd. The changes were implemented in record time. Following is a fine example of true teamwork and superior achievement of results against all obstacles.

  20. VizieR Online Data Catalog: Catalog of Type-1 AGNs from SDSS-DR7 (Oh+, 2015)

    NASA Astrophysics Data System (ADS)

    Oh, K.; Yi, S. K.; Schawinski, K.; Koss, M.; Trakhtenbrot, B.; Soto, K.

    2015-08-01

    We have recently identified a substantial number of type 1 active galactic nuclei (AGNs) featuring weak broad-line regions (BLRs) at z<0.2 from detailed analysis of galaxy spectra in the Sloan Digital Sky Survey Data Release 7. These objects predominantly show a stellar continuum but also a broad Hα emission line, indicating the presence of a low-luminosity AGN oriented so that we are viewing the central engine directly without significant obscuration. These accreting black holes have previously eluded detection due to their weak nature. The newly discovered BLR AGNs have increased the number of known type 1 AGNs by 49%. Some of these new BLR AGNs were detected with the Chandra X-ray Observatory, and their X-ray properties confirm that they are indeed type 1 AGNs. Based on our new and more complete catalog of type 1 AGNs, we derived the type 1 fraction of AGNs as a function of [OIII]λ5007 emission luminosity and explored the possible dilution effect on obscured AGNs due to star formation. The new type 1 AGN fraction shows much more complex behavior with respect to black hole mass and bolometric luminosity than has been suggested previously by the existing receding torus model. The type 1 AGN fraction is sensitive to both of these factors, and there seems to be a sweet spot (ridge) in the diagram of black hole mass and bolometric luminosity. Furthermore, we present the possibility that the Eddington ratio plays a role in determining opening angles. (2 data files).

  1. Increased diffuse radiation fraction does not significantly accelerate plant growth

    NASA Astrophysics Data System (ADS)

    Angert, Alon; Krakauer, Nir

    2010-05-01

    A recent modelling study (Mercado et al., 2009) claims that increased numbers of scattering aerosols are responsible for a substantial fraction of the terrestrial carbon sink in recent decades because higher diffuse light fraction enhances plant net primary production (NPP). Here we show that observations of atmospheric CO2 seasonal cycle and tree ring data indicate that the relation between diffuse light and NPP is actually quite weak on annual timescales. The inconsistency of these data with the modelling results may arise because the relationships used to quantify the enhancement of NPP were calibrated with eddy covariance measurements of hourly carbon uptake. The effect of diffuse-light fraction on carbon uptake could depend on timescale, since this effect varies rapidly as sun angle and cloudiness change, and since plants can respond dynamically over various timescales to change in incoming radiation. Volcanic eruptions, such as the eruption of Mount Pinatubo in 1991, provide the best available tests for the effect of an annual-scale increase in the diffuse light fraction. Following the Pinatubo Eruption, in 1992 and 1993, a sharp decrease in the atmospheric CO2 growth rate was observed. This could have resulted from enhanced plant carbon uptake. Mercado et al. (2009) argue that largely as a result of the (volcanic aerosol driven) increase in diffuse light fraction, NPP was elevated in 1992, particularly between 25° N-45° N where annual NPP was modelled to be ~0.8 PgC (~10%) above average. In a previous study (Angert et al., 2004) a biogeochemical model (CASA) linked to an atmospheric tracer model (MATCH), was used to show that a diffuse-radiation driven increase in NPP in the extratropics will enhance carbon uptake mostly in summer, leading to a lower CO2 seasonal minimum. Here we use a 'toy model' to show that this conclusion is general and model-independent. The model shows that an enhanced sink of 0.8 PgC, similar to that modelled by Mercado et al. (2009

  2. The cosmic evolution of massive black holes in the Horizon-AGN simulation

    NASA Astrophysics Data System (ADS)

    Volonteri, M.; Dubois, Y.; Pichon, C.; Devriendt, J.

    2016-08-01

    We analyse the demographics of black holes (BHs) in the large-volume cosmological hydrodynamical simulation Horizon-AGN. This simulation statistically models how much gas is accreted on to BHs, traces the energy deposited into their environment and, consequently, the back-reaction of the ambient medium on BH growth. The synthetic BHs reproduce a variety of observational constraints such as the redshift evolution of the BH mass density and the mass function. Strong self-regulation via AGN feedback, weak supernova feedback, and unresolved internal processes result in a tight BH-galaxy mass correlation. Starting at z ˜ 2, tidal stripping creates a small population of BHs over-massive with respect to the halo. The fraction of galaxies hosting a central BH or an AGN increases with stellar mass. The AGN fraction agrees better with multi-wavelength studies, than single-wavelength ones, unless obscuration is taken into account. The most massive haloes present BH multiplicity, with additional BHs gained by ongoing or past mergers. In some cases, both a central and an off-centre AGN shine concurrently, producing a dual AGN. This dual AGN population dwindles with decreasing redshift, as found in observations. Specific accretion rate and Eddington ratio distributions are in good agreement with observational estimates. The BH population is dominated in turn by fast, slow, and very slow accretors, with transitions occurring at z = 3 and z = 2, respectively.

  3. The cosmic evolution of massive black holes in the Horizon-AGN simulation

    NASA Astrophysics Data System (ADS)

    Volonteri, M.; Dubois, Y.; Pichon, C.; Devriendt, J.

    2016-08-01

    We analyse the demographics of black holes (BHs) in the large-volume cosmological hydrodynamical simulation Horizon-AGN. This simulation statistically models how much gas is accreted onto BHs, traces the energy deposited into their environment and, consequently, the back-reaction of the ambient medium on BH growth. The synthetic BHs reproduce a variety of observational constraints such as the redshift evolution of the BH mass density and the mass function. Strong self-regulation via AGN feedback, weak supernova feedback, and unresolved internal processes result in a tight BH-galaxy mass correlation. Starting at z~2, tidal stripping creates a small population of BHs over-massive with respect to the halo. The fraction of galaxies hosting a central BH or an AGN increases with stellar mass. The AGN fraction agrees better with multi-wavelength studies, than single-wavelength ones, unless obscuration is taken into account. The most massive halos present BH multiplicity, with additional BHs gained by ongoing or past mergers. In some cases, both a central and an off-centre AGN shine concurrently, producing a dual AGN. This dual AGN population dwindles with decreasing redshift, as found in observations. Specific accretion rate and Eddington ratio distributions are in good agreement with observational estimates. The BH population is dominated in turn by fast, slow, and very slow accretors, with transitions occurring at z=3 and z=2 respectively.

  4. DUAL SUPERMASSIVE BLACK HOLE CANDIDATES IN THE AGN AND GALAXY EVOLUTION SURVEY

    SciTech Connect

    Comerford, Julia M.; Schluns, Kyle; Greene, Jenny E.; Cool, Richard J.

    2013-11-01

    Dual supermassive black holes (SMBHs) with kiloparsec-scale separations in merger-remnant galaxies are informative tracers of galaxy evolution, but the avenue for identifying them in large numbers for such studies is not yet clear. One promising approach is to target spectroscopic signatures of systems where both SMBHs are fueled as dual active galactic nuclei (AGNs), or where one SMBH is fueled as an offset AGN. Dual AGNs may produce double-peaked narrow AGN emission lines, while offset AGNs may produce single-peaked narrow AGN emission lines with line-of-sight velocity offsets relative to the host galaxy. We search for such dual and offset systems among 173 Type 2 AGNs at z < 0.37 in the AGN and Galaxy Evolution Survey (AGES), and we find two double-peaked AGNs and five offset AGN candidates. When we compare these results to a similar search of the DEEP2 Galaxy Redshift Survey and match the two samples in color, absolute magnitude, and minimum velocity offset, we find that the fraction of AGNs that are dual SMBH candidates increases from z = 0.25 to z = 0.7 by a factor of ∼6 (from 2/70 to 16/91, or 2.9{sup +3.6}{sub -1.9}% to 18{sup +5}{sub -5}%). This may be associated with the rise in the galaxy merger fraction over the same cosmic time. As further evidence for a link with galaxy mergers, the AGES offset and dual AGN candidates are tentatively ∼3 times more likely than the overall AGN population to reside in a host galaxy that has a companion galaxy (from 16/173 to 2/7, or 9{sup +3}{sub -2}% to 29{sub -19}{sup +26}%). Follow-up observations of the seven offset and dual AGN candidates in AGES will definitively distinguish velocity offsets produced by dual SMBHs from those produced by narrow-line region kinematics, and will help sharpen our observational approach to detecting dual SMBHs.

  5. The dependency of AGN infrared colour-selection on source luminosity and obscuration. An observational perspective in CDFS and COSMOS

    NASA Astrophysics Data System (ADS)

    Messias, H.; Afonso, J. M.; Salvato, M.; Mobasher, B.; Hopkins, A. M.

    2014-02-01

    Aims: This work addresses the AGN IR-selection dependency on intrinsic source luminosity and obscuration, in order to identify and characterise biases that could affect conclusions in studies. Methods: We study IR-selected AGN in the Chandra Deep Field South (CDFS) survey and in the Cosmological Survey (COSMOS). The AGN sample is divided into low and high X-ray luminosity classes and into unobscured (type-1) and obscured (type-2) classes by means of X-ray and optical spectroscopy data. Specifically in the X-ray regime, we adopt the intrinsic luminosity taking the estimated column density (NH) into account. We also take the opportunity to highlight important differences resulting from adopting different methods of assessing AGN obscuration. Results: In agreement with previous studies, we also find that AGN IR-selection efficiency shows a decrease with decreasing source AGN X-ray luminosity. For the intermediate-luminosity AGN population (43.3 ≲ log (LX [erg s-1] ) ≲ 44), the efficiency also worsens with increasing obscuration (NH). The same sample also shows an evolution with cosmic time of the obscured fraction at the highest X-ray luminosities, independently of the adopted type-1/type-2 classification method. Conclusions: We confirm that AGN IR-selection is genuinely biased towards unobscured AGNe, but only at intermediate luminosities. At the highest luminosities, where AGN IR-selection is more efficient, there is no obscuration bias. We show that type-1 AGNe are intrinsically more luminous than type-2 AGNe only at z ≲ 1.6, thus resulting in more type-1 AGN being selected when the IR survey is shallower. Based on this and other studies, we conclude that deep hard-X-ray coverages, high-resolution IR imaging, or a combination of IR and radio data are required to recover the lower luminosity obscured AGN population. In addition, wide IR surveys are needed to recover the rare powerful, obscured AGN population. Finally, when the James Webb Space Telescope comes

  6. The roles of star formation and AGN activity of IRS sources in the HerMES fields

    NASA Astrophysics Data System (ADS)

    Feltre, A.; Hatziminaoglou, E.; Hernán-Caballero, A.; Fritz, J.; Franceschini, A.; Bock, J.; Cooray, A.; Farrah, D.; Solares, E. A. González; Ibar, E.; Isaak, K. G.; Faro, B. Lo; Marchetti, L.; Oliver, S. J.; Page, M. J.; Rigopoulou, D.; Roseboom, I. G.; Symeonidis, M.; Vaccari, M.

    2013-09-01

    In this work, we explore the impact of the presence of an active galactic nucleus (AGN) on the mid- and far-infrared (IR) properties of galaxies as well as the effects of simultaneous AGN and starburst activity in the same galaxies. To do this, we apply a multicomponent, multiband spectral synthesis technique to a sample of 250 μm selected galaxies of the Herschel Multi-tiered Extragalactic Survey (HerMES), with Infrared Spectrograph (IRS) spectra available for all galaxies. Our results confirm that the inclusion of the IRS spectra plays a crucial role in the spectral analysis of galaxies with an AGN component improving the selection of the best-fitting hot dust (torus) model. We find a correlation between the obscured star formation rate, SFRIR, derived from the IR luminosity of the starburst component, and SFRPAH, derived from the luminosity of the PAH features, LPAH, with SFRFIR taking higher values than SFRPAH. The correlation is different for AGN- and starburst-dominated objects. The ratio of LPAH to that of the starburst component, LPAH/LSB, is almost constant for AGN-dominated objects but decreases with increasing LSB for starburst-dominated objects. SFRFIR increases with the accretion luminosity, Lacc, with the increase less prominent for the very brightest, unobscured AGN-dominated sources. We find no correlation between the masses of the hot (AGN-heated) and cold (starburst-heated) dust components. We interpret this as a non-constant fraction of gas driven by the gravitational effects to the AGN while the starburst is ongoing. We also find no evidence of the AGN affecting the temperature of the cold dust component, though this conclusion is mostly based on objects with a non-dominant AGN component. We conclude that our findings do not provide evidence that the presence of AGN affects the star formation process in the host galaxy, but rather that the two phenomena occur simultaneously over a wide range of luminosities.

  7. AGN from HeII: AGN host galaxy properties & demographics

    NASA Astrophysics Data System (ADS)

    Baer, Rudolf E.; Schawinski, Kevin; Weigel, Anna

    2016-01-01

    We present an analysis of HeII emitting objects classified as AGN. In a sample of 81'192 galaxies taken from the seventh data release (DR7) of the Sloan Digital Sky Survey in the redshift interval 0.02 < z < 0.05 and with r < 17 AB mag, the Baldwin, Philips & Terlevitsch 1981 method (BPT) identifies 1029 objects as active galactic nuclei. By applying an analysis using HeII λ 4686 emission lines, based on Shirazi & Binchmann 2012, we have identified an additional 283 active galactic nuclei, which were missed by the BPT method. This represents an increase of over 25 %. The characteristics of the HeII selected AGN are different from the AGN found through the PBT; the colour - mass diagram and the colour histogram both show that HeII selected AGN are bluer. This new selection technique can help inform galaxy black hole coevolution scenarios.

  8. The nature and origin of Narrow Line AGN activity in a sample of isolated SDSS galaxies

    NASA Astrophysics Data System (ADS)

    Coziol, R.; Torres-Papaqui, J. P.; Plauchu-Frayn, I.; Islas-Islas, J. M.; Ortega-Minakata, R. A.; Neri-Larios, D. M.; Andernach, H.

    2011-10-01

    We discuss the nature and origin of the nuclear activity observed in a sample of 292 SDSS narrow-emission-line galaxies, considered to have formed and evolved in isolation. The fraction of Narrow Line AGNs (NLAGNs) and Transition type Objects (TOs; a NLAGN with circumnuclear star formation) amounts to 64% of the galaxies. We verify that the probability for a galaxy to show an AGN characteristic increases with the bulge mass of the galaxy (Torres-Papaqui et al. 2011), and find evidence that this trend is really a by-product of the morphology, suggesting that the AGN phenomenon is intimately connected with the formation process of the galaxies. The NLAGNs in our sample are consistent with a scaled-down or powered-down versions of quasars and Broad Line AGNs.

  9. The INTEGRAL/IBIS AGN catalogue - I. X-ray absorption properties versus optical classification

    NASA Astrophysics Data System (ADS)

    Malizia, A.; Bassani, L.; Bazzano, A.; Bird, A. J.; Masetti, N.; Panessa, F.; Stephen, J. B.; Ubertini, P.

    2012-11-01

    In this work we present the most comprehensive INTEGRAL active galactic nucleus (AGN) sample. It lists 272 AGN for which we have secure optical identifications, precise optical spectroscopy and measured redshift values plus X-ray spectral information, i.e. 2-10 and 20-100 keV fluxes plus column density. Here we mainly use this sample to study the absorption properties of active galaxies, to probe new AGN classes and to test the AGN unification scheme. We find that half (48 per cent) of the sample is absorbed, while the fraction of Compton-thick AGN is small (˜7 per cent). In line with our previous analysis, we have however shown that when the bias towards heavily absorbed objects which are lost if weak and at large distance is removed, as it is possible in the local Universe, the above fractions increase to become 80 and 17 per cent. We also find that absorption is a function of source luminosity, which implies some evolution in the obscuration properties of AGN. A few peculiar classes, so far poorly studied in the hard X-ray band, have been detected and studied for the first time such as 5 X-ray bright optically normal galaxies, 5 type 2 QSOs and 11 low-ionization nuclear emission regions. In terms of optical classification, our sample contains 57 per cent of type 1 and 43 per cent of type 2 AGN; this subdivision is similar to that found in X-rays if unabsorbed versus absorbed objects are considered, suggesting that the match between optical and X-ray classifications is overall good. Only a small percentage of sources (12 per cent) does not fulfil the expectation of the unified theory as we find 22 type 1 AGN which are absorbed and 10 type 2 AGN which are unabsorbed. Studying in depth these outliers we found that most of the absorbed type 1 AGN have X-ray spectra characterized by either complex or warm/ionized absorption more likely due to ionized gas located in an accretion disc wind or in the biconical structure associated with the central nucleus, therefore

  10. Constraining AGN triggering mechanisms through the clustering analysis of active black holes

    NASA Astrophysics Data System (ADS)

    Gatti, M.; Shankar, F.; Bouillot, V.; Menci, N.; Lamastra, A.; Hirschmann, M.; Fiore, F.

    2016-02-01

    The triggering mechanisms for active galactic nuclei (AGN) are still debated. Some of the most popular ones include galaxy interactions (IT) and disc instabilities (DIs). Using an advanced semi-analytic model (SAM) of galaxy formation, coupled to accurate halo occupation distribution modelling, we investigate the imprint left by each separate triggering process on the clustering strength of AGN at small and large scales. Our main results are as follows: (i) DIs, irrespective of their exact implementation in the SAM, tend to fall short in triggering AGN activity in galaxies at the centre of haloes with Mh > 1013.5 h-1 M⊙. On the contrary, the IT scenario predicts abundance of active central galaxies that generally agrees well with observations at every halo mass. (ii) The relative number of satellite AGN in DIs at intermediate-to-low luminosities is always significantly higher than in IT models, especially in groups and clusters. The low AGN satellite fraction predicted for the IT scenario might suggest that different feeding modes could simultaneously contribute to the triggering of satellite AGN. (iii) Both scenarios are quite degenerate in matching large-scale clustering measurements, suggesting that the sole average bias might not be an effective observational constraint. (iv) Our analysis suggests the presence of both a mild luminosity and a more consistent redshift dependence in the AGN clustering, with AGN inhabiting progressively less massive dark matter haloes as the redshift increases. We also discuss the impact of different observational selection cuts in measuring AGN clustering, including possible discrepancies between optical and X-ray surveys.

  11. The 60-month all-sky BAT Survey of AGN and the Anisotropy of Nearby AGN

    SciTech Connect

    Ajello, M.; Alexander, D.M.; Greiner, J.; Madejski, G.M.; Gehrels, N.; Burlon, D.; /Garching, Max Planck Inst., MPE

    2012-04-02

    Surveys above 10 keV represent one of the the best resources to provide an unbiased census of the population of Active Galactic Nuclei (AGN). We present the results of 60 months of observation of the hard X-ray sky with Swift/BAT. In this timeframe, BAT detected (in the 15-55 keV band) 720 sources in an all-sky survey of which 428 are associated with AGN, most of which are nearby. Our sample has negligible incompleteness and statistics a factor of {approx}2 larger over similarly complete sets of AGN. Our sample contains (at least) 15 bona-fide Compton-thick AGN and 3 likely candidates. Compton-thick AGN represent a {approx}5% of AGN samples detected above 15 keV. We use the BAT dataset to refine the determination of the LogN-LogS of AGN which is extremely important, now that NuSTAR prepares for launch, towards assessing the AGN contribution to the cosmic X-ray background. We show that the LogN-LogS of AGN selected above 10 keV is now established to a {approx}10% precision. We derive the luminosity function of Compton-thick AGN and measure a space density of 7.9{sub -2.9}{sup +4.1} x 10{sup -5} Mpc{sup -3} for objects with a de-absorbed luminosity larger than 2 x 10{sup 42} erg s{sup -1}. As the BAT AGN are all mostly local, they allow us to investigate the spatial distribution of AGN in the nearby Universe regardless of absorption. We find concentrations of AGN that coincide spatially with the largest congregations of matter in the local ({le} 85 Mpc) Universe. There is some evidence that the fraction of Seyfert 2 objects is larger than average in the direction of these dense regions.

  12. FRACTIONAL CALCIUM ABSORPTION IS INCREASED IN GIRLS WITH RETT SYNDROME

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rett Syndrome (RTT), an X-linked neurodevelopmental disorder primarily affecting girls, is characterized in part by osteopenia and increased risk of skeletal fractures. We hypothesized that causally related factors may include decreased intestinal Ca absorption relative to dietary Ca intakes and in...

  13. Type 1 AGN at low z - III. The optical narrow-line ratios

    NASA Astrophysics Data System (ADS)

    Stern, Jonathan; Laor, Ari

    2013-05-01

    We present the optical narrow-line ratios in a Sloan Digital Sky Survey (SDSS) based sample of 3175 broad Hα selected type 1 active galactic nuclei (AGN), and explore their positions in the BPT diagrams as a function of the AGN and the host properties. We find the following: (1) the luminosities of all measured narrow lines (Hα, Hβ, [O III], [N II], [S II], [O I]) show a Baldwin relation relative to the broad Hα luminosity LbHα, with slopes in the range of 0.53-0.72. (2) About 20 per cent of the type 1 AGN reside within the `Composite' and `star-forming' (SF) regions of the Baldwin, Phillips & Terlevich (BPT) diagrams. These objects also show excess narrow Hα and ultraviolet (UV) luminosities, for their LbHα, consistent with contribution from star formation which dominates the narrow-lines emission, as expected from their positions in the BPT diagrams. (3) The type 1 which reside within the AGN region in the BPT diagrams, are offset to lower [S II]/Hα and [N II]/Hα luminosity ratios, compared to type 2 AGN. This offset is a selection effect, related to the lower AGN/host luminosity selection of the type 2 AGN selected from the SDSS galaxy sample. (4) The [N II]/Hα and [N II]/[S II] ratios in type 1 AGN increase with the host mass, as expected if the mass-metallicity relation of quiescent galaxies holds for the AGN narrow-line region (NLR). (5) The broad lines optical Fe II is higher for a higher [N II]/Hα, at a fixed Lbol and Eddington ratio L/LEdd. This suggests that the broad line region metallicity is also related to the host mass. (6) The fraction of AGN which are low-ionization nuclear emission-line regions (LINERs) increases sharply with decreasing L/LEdd. This fraction is the same for type 1 and type 2 AGN. (7) The BPT position is unaffected by the amount of dust extinction of the optical-UV continuum, which suggests that the extincting dust resides on scales larger than the NLR.

  14. Higher prevalence of X-ray selected AGN in intermediate-age galaxies up to z ˜ 1

    NASA Astrophysics Data System (ADS)

    Hernán-Caballero, Antonio; Alonso-Herrero, Almudena; Pérez-González, Pablo G.; Barro, Guillermo; Aird, James; Ferreras, Ignacio; Cava, Antonio; Cardiel, Nicolás; Esquej, Pilar; Gallego, Jesús; Nandra, Kirpal; Rodríguez-Zaurín, Javier

    2014-10-01

    We analyse the stellar populations in the host galaxies of 53 X-ray selected optically dull active galactic nuclei (AGN) at 0.34 < z < 1.07 with ultradeep (mAB = 26.5, 3σ) optical medium-band (R ˜ 50) photometry from the Survey for High-z Absorption Red and Dead Sources (SHARDS). The spectral resolution of SHARDS allows us to consistently measure the strength of the 4000 Å break, Dn(4000), a reliable age indicator for stellar populations. We confirm that most X-ray selected moderate-luminosity AGN (LX < 1044 erg s-1) are hosted by massive galaxies (typically M* >1010.5 M⊙) and that the observed fraction of galaxies hosting an AGN increases with the stellar mass. A careful selection of random control samples of inactive galaxies allows us to remove the stellar mass and redshift dependences of the AGN fraction to explore trends with several stellar age indicators. We find no significant differences in the distribution of the rest-frame U - V colour for AGN hosts and inactive galaxies, in agreement with previous results. However, we find significantly shallower 4000 Å breaks in AGN hosts, indicative of younger stellar populations. With the help of a model-independent determination of the extinction, we obtain extinction-corrected U - V colours and light-weighted average stellar ages. We find that AGN hosts have younger stellar populations and higher extinction compared to inactive galaxies with the same stellar mass and at the same redshift. We find a highly significant excess of AGN hosts with Dn(4000) ˜ 1.4 and light-weighted average stellar ages of 300-500 Myr, as well as a deficit of AGN in intrinsic red galaxies. We interpret failure in recognizing these trends in previous studies as a consequence of the balancing effect in observed colours of the age-extinction degeneracy.

  15. VizieR Online Data Catalog: AGN activity in isolated SDSS galaxies (Coziol+, 2011)

    NASA Astrophysics Data System (ADS)

    Coziol, R.; Torres-Papaqui, J. P.; Plauchu-Frayn, I.; Islas-Islas, J. M.; Ortega-Minakata, R. A.; Neri-Larios, D. M.; Andernach, H.

    2011-09-01

    We discuss the nature and origin of the nuclear activity observed in a sample of 292 SDSS narrow-emission-line galaxies, considered to have formed and evolved in isolation. All these galaxies are spiral like and show some kind of nuclear activity. The fraction of Narrow Line AGNs (NLAGNs) and Transition type Objects (TOs; a NLAGN with circumnuclear star formation) is relatively high, amounting to 64% of the galaxies. There is a definite trend for the NLAGNs to appear in early-type spirals, while the star forming galaxies and TOs are found in later-type spirals. We verify that the probability for a galaxy to show an AGN characteristic increases with the bulge mass of the galaxy (Torres-Papaqui et al. 2011), and find evidence that this trend is really a by-product of the morphology, suggesting that the AGN phenomenon is intimately connected with the formation process of the galaxies. Consistent with this interpretation, we establish a strong connection between the astration rate -- the efficiency with which the gas is transformed into stars - the AGN phenomenon, and the gravitational binding energy of the galaxies: the higher the binding energy, the higher the astration rate and the higher the probability to find an AGN. The NLAGNs in our sample are consistent with scaled-down or powered-down versions of quasars and Broad Line AGNs. (2 data files).

  16. Low luminosity AGNs in the local universe

    NASA Astrophysics Data System (ADS)

    Ikiz, Tuba; Peletier, Reynier F.; Yesilyaprak, Cahit

    2016-04-01

    Galaxies are known to contain black holes (e.g. Ferrarese & Merritt 2000), whose mass correlates with the mass of their bulge. A fraction of them also has an Active Galactic Nucleus (AGN), showing excess emission thought to be due to accretion of mass by the supermassive black hole at the center of the galaxy. It is thought that AGNs play a very important role during the formation of galaxies by creating large outflows that stop star formation in the galaxy (see e.g. Kormendy & Ho 2013). The aim is to detect the fraction of Low Luminosity Active Galactic Nucleus (LLAGN) in the nearby Universe. At present, they are typically found using optical spectroscopy (e.g. Kauffmann, Heckman et al. 2003), who discuss the influence of the AGN on the host galaxy and vice versa. However, optical spectra are seriously affected by extinction in these generally very dusty objects, and therefore can only give us partial information about the AGN. I used a newly-found method, and apply it to the S4G sample, a large, complete, sample of nearby galaxies, which I am studying in detail with a large collaboration, to detect the fraction of low luminosity AGNs, and to better understand the relation between AGNs and their host galaxy which is thought to be crucial for their formation.

  17. Decreased specific star formation rates in AGN host galaxies

    NASA Astrophysics Data System (ADS)

    Shimizu, T. Taro; Mushotzky, Richard F.; Meléndez, Marcio; Koss, Michael; Rosario, David J.

    2015-09-01

    We investigate the location of an ultra-hard X-ray selected sample of active galactic nuclei (AGN) from the Swift Burst Alert Telescope (BAT) catalogue with respect to the main sequence (MS) of star-forming galaxies using Herschel-based measurements of the star formation rate (SFR) and M*'s from Sloan Digital Sky Survey photometry where the AGN contribution has been carefully removed. We construct the MS with galaxies from the Herschel Reference Survey and Herschel Stripe 82 Survey using the exact same methods to measure the SFR and M* as the Swift/BAT AGN. We find that a large fraction of the Swift/BAT AGN lie below the MS indicating decreased specific SFR (sSFR) compared to non-AGN galaxies. The Swift/BAT AGN are then compared to a high-mass galaxy sample (CO Legacy Database for GALEX Arecibo SDSS Survey, COLD GASS), where we find a similarity between the AGN in COLD GASS and the Swift/BAT AGN. Both samples of AGN lie firmly between star-forming galaxies on the MS and quiescent galaxies far below the MS. However, we find no relationship between the X-ray luminosity and distance from the MS. While the morphological distribution of the BAT AGN is more similar to star-forming galaxies, the sSFR of each morphology is more similar to the COLD GASS AGN. The merger fraction in the BAT AGN is much higher than the COLD GASS AGN and star-forming galaxies and is related to distance from the MS. These results support a model in which bright AGN tend to be in high-mass star-forming galaxies in the process of quenching which eventually starves the supermassive black hole itself.

  18. Radio Loud AGNs are Mergers

    NASA Astrophysics Data System (ADS)

    Chiaberge, Marco; Gilli, Roberto; Lotz, Jennifer M.; Norman, Colin

    2015-06-01

    We measure the merger fraction of Type 2 radio-loud and radio-quiet active galactic nuclei (AGNs) at z\\gt 1 using new samples. The objects have Hubble Space Telescope (HST) images taken with Wide Field Camera 3 (WFC3) in the IR channel. These samples are compared to the 3CR sample of radio galaxies at z\\gt 1 and to a sample of non-active galaxies. We also consider lower redshift radio galaxies with HST observations and previous generation instruments (NICMOS and WFPC2). The full sample spans an unprecedented range in both redshift and AGN luminosity. We perform statistical tests to determine whether the different samples are differently associated with mergers. We find that all (92%-14%+8%) radio-loud galaxies at z\\gt 1 are associated with recent or ongoing merger events. Among the radio-loud population there is no evidence for any dependence of the merger fraction on either redshift or AGN power. For the matched radio-quiet samples, only 38%-15+16 are merging systems. The merger fraction for the sample of non-active galaxies at z\\gt 1 is indistinguishable from radio-quiet objects. This is strong evidence that mergers are the triggering mechanism for the radio-loud AGN phenomenon and the launching of relativistic jets from supermassive black holes (SMBHs). We speculate that major black hole (BH)–BH mergers play a major role in spinning up the central SMBHs in these objects.

  19. Enhanced star formation rates in AGN hosts with respect to inactive galaxies from PEP-Herschel observations

    NASA Astrophysics Data System (ADS)

    Santini, P.; Rosario, D. J.; Shao, L.; Lutz, D.; Maiolino, R.; Alexander, D. M.; Altieri, B.; Andreani, P.; Aussel, H.; Bauer, F. E.; Berta, S.; Bongiovanni, A.; Brandt, W. N.; Brusa, M.; Cepa, J.; Cimatti, A.; Daddi, E.; Elbaz, D.; Fontana, A.; Förster Schreiber, N. M.; Genzel, R.; Grazian, A.; Le Floc'h, E.; Magnelli, B.; Mainieri, V.; Nordon, R.; Pérez Garcia, A. M.; Poglitsch, A.; Popesso, P.; Pozzi, F.; Riguccini, L.; Rodighiero, G.; Salvato, M.; Sanchez-Portal, M.; Sturm, E.; Tacconi, L. J.; Valtchanov, I.; Wuyts, S.

    2012-04-01

    We compare the average star formation (SF) activity in X-ray selected AGN hosts with a mass-matched control sample of inactive galaxies, including both star forming and quiescent sources, in the 0.5 < z < 2.5 redshift range. Recent observations carried out by PACS, the 60-210 μm photometric camera on board the Herschel Space Observatory, in GOODS-S, GOODS-N and COSMOS allow us to obtain an unbiased estimate of the far-IR luminosity, and hence of the SF properties, of the two samples. Accurate AGN host stellar mass estimates are obtained by decomposing their total emission into the stellar and the nuclear components. We report evidence of a higher average SF activity in AGN hosts with respect to the control sample of inactive galaxies. The level of SF enhancement is modest (~0.26 dex at ~3σ confidence level) at low X-ray luminosities (LX ≲ 1043.5 erg s-1) and more pronounced (0.56 dex at > 10σ confidence level) in the hosts of luminous AGNs. However, when comparing to star forming galaxies only, AGN hosts are found broadly consistent with the locus of their "main sequence". We investigate the relative far-IR luminosity distributions of active and inactive galaxies, and find a higher fraction of PACS detected, hence normal and highly star forming systems among AGN hosts. Although different interpretations are possible, we explain our findings as a consequence of a twofold AGN growth path: faint AGNs evolve through secular processes, with instantaneous AGNaccretion not tightly linked to the current total SF in the host galaxy, while the luminous AGNs co-evolve with their hosts through periods of enhanced AGN activity and star formation, possibly through major mergers. While an increased SF activity with respect to inactive galaxies of similar mass is expected in the latter, we interpret the modest SF offsets measured in low-LX AGN hosts as either a) generated by non-synchronous accretion and SF histories in a merger scenario or b) due to possible connections

  20. Type 1 AGN at low z- I. Emission properties

    NASA Astrophysics Data System (ADS)

    Stern, Jonathan; Laor, Ari

    2012-06-01

    We analyse the emission properties of a new sample of 3579 type 1 AGN, selected from Sloan Digital Sky Survey (SDSS) Data Release 7 based on the detection of broad Hα emission. The sample extends over a broad Hα luminosity LbHα of ? and a broad Hα full width at half-maximum (FWHM) of ?, which covers the range of black hole mass 106 < MBH/M⊙ < 109.5 and luminosity in Eddington units 10-3 < L/LEdd < 1. We combine ROSAT, GALEX and 2MASS observations to form the spectral energy distribution (SED) from 2.2 ?m to 2 keV. We find the following. (1) The distribution of the Hα FWHM values is independent of luminosity. (2) The observed mean optical-ultraviolet (optical-UV) SED is well matched by a fixed-shape SED of luminous quasars, which scales linearly with LbHα, and a host galaxy contribution. (3) The host galaxy r-band (fibre) luminosity function follows well the luminosity function of inactive non-emission-line galaxies (NEGs), consistent with a fixed fraction of ˜3 per cent of NEGs hosting an AGN, regardless of the host luminosity. (4) The hosts of lower luminosity AGN have a mean z-band luminosity and u-z colour which are identical to NEGs with the same redshift distribution. With increasing LbHα the AGN hosts become bluer and less luminous than NEGs. The implied increasing star formation rate with LbHα is consistent with the relation for SDSS type 2 AGN of similar bolometric luminosity. (5) The optical-UV SED of the more luminous AGN shows a small dispersion, consistent with dust reddening of a blue SED, as expected for thermal thin accretion disc emission. (6) There is a rather tight relation between ? and LbHα, which provides a useful probe for unobscured (true) type 2 AGN. (7) The primary parameter that drives the X-ray to UV emission ratio is luminosity, rather than MBH or L/LEdd.

  1. Identifying Luminous AGN in Deep Surveys: Revised IRAC Selection Criteria

    NASA Astrophysics Data System (ADS)

    Donley, Jennifer; Koekemoer, A. M.; Brusa, M.; Capak, P.; Cardamone, C. N.; Civano, F.; Ilbert, O.; Impey, C. D.; Kartaltepe, J.; Miyaji, T.; Salvato, M.; Sanders, D. B.; Trump, J. R.; Zamorani, G.

    2012-01-01

    Spitzer IRAC selection is a powerful tool for identifying luminous AGN. The AGN selection wedges currently in use, however, are heavily contaminated by star-forming galaxies, especially at high redshift. Using the large samples of luminous AGN and high-redshift star-forming galaxies in COSMOS, we redefine the AGN selection criteria for use in deep IRAC surveys. The new IRAC criteria are designed to be both highly complete and reliable, and incorporate the best aspects of the current AGN selection wedges and of infrared power-law selection while excluding high redshift star-forming galaxies selected via the BzK, DRG, LBG, and SMG criteria. At QSO-luminosities of log L(2-10 keV)>44, the new IRAC criteria recover 75% of the hard X-ray and IRAC-detected XMM-COSMOS sample, yet only 37% of the IRAC AGN candidates have X-ray counterparts, a fraction that rises to 51% in regions with Chandra exposures of 50-160 ks. X-ray stacking of the individually X-ray non-detected AGN candidates leads to a hard X-ray signal indicative of heavily obscured to mildly Compton-thick obscuration (log NH >= 23.7). While IRAC selection recovers a substantial fraction of luminous unobscured and obscured AGN, it is incomplete to low-luminosity and host-dominated AGN.

  2. AGN-starburst evolutionary connection : a physical interpretation based on radiative feedback

    NASA Astrophysics Data System (ADS)

    Ishibashi, W.; Fabian, A. C.

    2016-08-01

    Observations point towards a close connection between nuclear starbursts, active galactic nuclei (AGN), and outflow phenomena. An evolutionary sequence, starting from a dust-obscured ultra-luminous infrared galaxy and eventually leading to an unobscured optical quasar, has been proposed and discussed in the literature. AGN feedback is usually invoked to expel the obscuring gas and dust in a blow-out event, but the underlying physical mechanism remains unclear. We consider AGN feedback driven by radiation pressure on dust, which directly acts on the obscuring dusty gas. We obtain that radiative feedback can potentially disrupt dense gas in the infrared-optically thick regime, and that an increase in the dust-to-gas fraction leads to an increase in the effective Eddington ratio. Thus the more dusty gas is preferentially expelled by radiative feedback, and the central AGN is prone to efficiently remove its own obscuring dust cocoon. Large amounts of dust imply heavy obscuration but also powerful feedback, suggesting a causal link between dust obscuration and blow-out. In this picture, AGN feedback and starburst phenomena are intrinsically coupled through the production of dust in supernova explosions, leading to a natural interpretation of the observed evolutionary path.

  3. Spectral Energy Distributions of Type 1 AGNs

    NASA Astrophysics Data System (ADS)

    Hao, Heng

    The spectral energy distributions (SEDs) of active galactic nuclei (AGNs) are essential to understand the physics of supermassive black holes (SMBHs) and their host galaxies. This thesis present a detailed study of AGN SED shapes in the optical-near infrared bands (0.3--3microm) for 413 X-ray selected Type 1 AGNs from the XMM-COSMOS Survey. We define a useful near-IR/optical index-index ('color-color') diagram to investigate the mixture of AGN continuum, host galaxy and reddening contributions. We found that ˜90% of the AGNs lie on mixing curves between the Elvis et al. (1994) mean AGN SED (E94) and a host galaxy, with only the modest reddening [E(B-V)=0.1--0.2] expected in type 1 AGNs. Lower luminosity and Eddington ratio objects have more host galaxy, as expected. The E94 template is remarkably good in describing the SED shape in the 0.3--3microrn decade of the spectrum over a range of 3.2 dex in LOPT, 2.7 dex in L/LEdd, and for redshifts up to 3. The AGN phenomenon is thus insensitive to absolute or relative accretion rate and to cosmic time. However, 10% of the AGNs are inconsistent with any AGN+host+reddening mix. These AGNs have weak or non-existent near-IR bumps, suggesting a lack of the hot dust characteristic of AGNs. The fraction of these hot-dust-poor AGNs evolves with redshift from 6% at low redshift (z < 2) to 20% at moderately high redshift (2 < z < 3.5). A similar fraction of HDP quasars are found in the Elvis et al. 1994 (BQS) and Richards et al. 2006 (SDSS) samples. The 1--3microm emission of the HDP quasars is a factor 2--4 smaller than the typical E94 AGN SED. The implied torus covering factor is 2%--29%, well below the 75% required by unified models. The weak hot dust emission seems to expose an extension of the accretion disk continuum in some of AGNs. For these, we estimate the outer edge of their accretion disks to lie at ˜104 Schwarzschild radii, more than ten times the gravitational stability radii. Either the host-dust is destroyed

  4. Analysis and Functional Consequences of Increased Fab-Sialylation of Intravenous Immunoglobulin (IVIG) after Lectin Fractionation

    PubMed Central

    Käsermann, Fabian; Boerema, David J.; Rüegsegger, Monika; Hofmann, Andreas; Wymann, Sandra; Zuercher, Adrian W.; Miescher, Sylvia

    2012-01-01

    It has been proposed that the anti-inflammatory effects of intravenous immunoglobulin (IVIG) might be due to the small fraction of Fc-sialylated IgG. In this study we biochemically and functionally characterized sialic acid-enriched IgG obtained by Sambucus nigra agglutinin (SNA) lectin fractionation. Two main IgG fractions isolated by elution with lactose (E1) or acidified lactose (E2) were analyzed for total IgG, F(ab’)2 and Fc-specific sialic acid content, their pattern of specific antibodies and anti-inflammatory potential in a human in vitro inflammation system based on LPS- or PHA-stimulated whole blood. HPLC and LC-MS testing revealed an increase of sialylated IgG in E1 and more substantially in the E2 fraction. Significantly, the increased amount of sialic acid residues was primarily found in the Fab region whereas only a minor increase was observed in the Fc region. This indicates preferential binding of the Fab sialic acid to SNA. ELISA analyses of a representative range of pathogen and auto-antigens indicated a skewed antibody pattern of the sialylated IVIG fractions. Finally, the E2 fraction exerted a more profound anti-inflammatory effect compared to E1 or IVIG, evidenced by reduced CD54 expression on monocytes and reduced secretion of MCP-1 (CCL2); again these effects were Fab- but not Fc-dependent. Our results show that SNA fractionation of IVIG yields a minor fraction (approx. 10%) of highly sialylated IgG, wherein the sialic acid is mainly found in the Fab region. The tested anti-inflammatory activity was associated with Fab not Fc sialylation. PMID:22675478

  5. Why are AGN found in high-mass galaxies?

    NASA Astrophysics Data System (ADS)

    Wang, Lan; Kauffmann, Guinevere

    2008-12-01

    There is a strong observed mass dependence of the fraction of nearby galaxies that contain either low-luminosity [low-ionization nuclear emission-line region (LINER) type] or higher luminosity (Seyfert or composite type) active galactic nuclei (AGN). This implies that either only a small fraction of low-mass galaxies contain black holes, or that the black holes in these systems only accrete rarely or at very low rates, and hence are generally not detectable as AGN. In this paper, we use semi-analytic models implemented in the Millennium Simulation to analyse the mass dependence of the merging histories of dark matter haloes and of the galaxies that reside in them. Only a few per cent of galaxies with stellar masses less than M* < 1010Msolar are predicted to have experienced a major merger. The fraction of galaxies that have experienced major mergers increases steeply at larger stellar masses. We argue that if a major merger is required to form the initial seed black hole, the mass dependence of AGN activity in local galaxies can be understood quite naturally. We then investigate when the major mergers that first create these black holes are predicted to occur. High-mass galaxies are predicted to have formed their first black holes at very early epochs. The majority of low-mass galaxies never experience a major merger and hence may not contain a black hole, but a significant fraction of the supermassive black holes that do exist in low-mass galaxies are predicted to have formed recently.

  6. OT1_pgandhi_1: What inflates the torus? Probing the physical properties of geometrically-thick buried AGN with high J CO lines

    NASA Astrophysics Data System (ADS)

    Gandhi, P.

    2010-07-01

    The most significant new population of active galactic nuclei (AGN) discovered in recent years is the 'buried AGN' population, uncovered by the Swift satellite. Sensitive X-ray spectroscopy shows characteristics of heavily obscured AGN in these sources, in addition to a very low scattering fraction of low energy photons, which is interpreted as a result of the AGN being buried in dust and gas tori which have an atypically high geometrical thickness. Comprising up to 20 per cent of the entire AGN population, this class constitutes a very important new family of sources, which may be at an interesting evolutionary phase in the AGN life cycle. Yet, very little is known about them, and usual isotropic indicators such as the optical [OIII] forbidden emission line fail to probe their intrinsic powers. The geometrically thick torus picture can result in 1) high gas and dust masses in the tori; 2) increased velocity dispersions and elevated temperatures and pressures; 3) a broad-band spectral energy distribution dominated by cool optically-thick clouds. Far infrared lines provide excellent probes of the physical conditions in the torus, and we intend to use several high J rotational CO lines to test the above picture with Herschel for the first time on several buried AGN for which detailed X-ray spectroscopy exists. These observations will also enable us to search for dynamical signatures of motion in the torus.

  7. THE OBSCURED FRACTION OF ACTIVE GALACTIC NUCLEI IN THE XMM-COSMOS SURVEY: A SPECTRAL ENERGY DISTRIBUTION PERSPECTIVE

    SciTech Connect

    Lusso, E.; Hennawi, J. F.; Richards, G. T.; Comastri, A.; Zamorani, G.; Vignali, C.; Gilli, R.; Treister, E.; Schawinski, K.; Salvato, M.

    2013-11-10

    The fraction of active galactic nucleus (AGN) luminosity obscured by dust and re-emitted in the mid-IR is critical for understanding AGN evolution, unification, and parsec-scale AGN physics. For unobscured (Type 1) AGNs, where we have a direct view of the accretion disk, the dust covering factor can be measured by computing the ratio of re-processed mid-IR emission to intrinsic nuclear bolometric luminosity. We use this technique to estimate the obscured AGN fraction as a function of luminosity and redshift for 513 Type 1 AGNs from the XMM-COSMOS survey. The re-processed and intrinsic luminosities are computed by fitting the 18 band COSMOS photometry with a custom spectral energy distribution fitting code, which jointly models emission from hot dust in the AGN torus, from the accretion disk, and from the host galaxy. We find a relatively shallow decrease of the luminosity ratio as a function of L{sub bol}, which we interpret as a corresponding decrease in the obscured fraction. In the context of the receding torus model, where dust sublimation reduces the covering factor of more luminous AGNs, our measurements require a torus height that increases with luminosity as h ∝ L{sub bol}{sup 0.3-0.4}. Our obscured-fraction-luminosity relation agrees with determinations from Sloan Digital Sky Survey censuses of Type 1 and Type 2 quasars and favors a torus optically thin to mid-IR radiation. We find a much weaker dependence of the obscured fraction on 2-10 keV luminosity than previous determinations from X-ray surveys and argue that X-ray surveys miss a significant population of highly obscured Compton-thick AGNs. Our analysis shows no clear evidence for evolution of the obscured fraction with redshift.

  8. Increasing trend of primary NO(2) exhaust emission fraction in Hong Kong.

    PubMed

    Tian, Linwei; Hossain, Sarah R; Lin, Hualiang; Ho, Kin Fai; Lee, Shun Cheng; Yu, Ignatius T S

    2011-12-01

    Despite the successful reduction in roadside NO( x ) levels, no such decrease has been detected in roadside NO(2) concentration in Hong Kong. One underlying cause could be the rising primary NO(2) fraction of the total emission of NO( x ). Primary NO(2) can be particularly detrimental to Hong Kong because a large fraction of the population are exposed to the traffic-related primary pollutants in the street canyons formed by congested high-rise buildings. In this study, hourly mean concentration data for roadside nitrogen oxides (NO( x )), nitrogen dioxide (NO(2)), and background ozone (O(3)) were used to estimate the mean primary NO(2) fraction from vehicle exhausts in Hong Kong. An overall increasing trend was observed for the primary NO(2) fraction (f-NO(2)) values in all the three roadside air monitoring sites. The primary NO(2) as a fraction of total NO( x ) (f-NO(2)) increased approximately from 2% in 1998 to 13% in 2008 in Hong Kong. The two particular periods of rising f-NO(2) coincided with the two implementation periods of the diesel retrofit programs for the light-duty vehicles and heavy-duty vehicles. Future vehicle emission control strategies should target not only total NO( x ) but also primary NO(2). Health benefit or disease burden estimates should be taken into account and updated in the process of policy planning and evaluation. PMID:21331790

  9. Method of increasing anhydrosugars, pyroligneous fractions and esterified bio-oil

    SciTech Connect

    Steele, Philip H; Yu, Fei; Li, Qi; Mitchell, Brian

    2014-12-30

    The device and method are provided to increase anhydrosugars yield during pyrolysis of biomass. This increase is achieved by injection of a liquid or gas into the vapor stream of any pyrolysis reactor prior to the reactor condensers. A second feature of our technology is the utilization of sonication, microwave excitation, or shear mixing of the biomass to increase the acid catalyst rate for demineralization or removal of hemicellulose prior to pyrolysis. The increased reactivity of these treatments reduces reaction time as well as the required amount of catalyst to less than half of that otherwise required. A fractional condensation system employed by our pyrolysis reactor is another feature of our technology. This system condenses bio-oil pyrolysis vapors to various desired fractions by differential temperature manipulation of individual condensers comprising a condenser chain.

  10. Obscured AGN Accretion Across Cosmic Time

    NASA Astrophysics Data System (ADS)

    Coil, Alison

    We propose to combine data from XMM-Newton, the Chandra X-ray Observatory, and the Spitzer Space Telescope with ground-based optical spectroscopy from Keck and Magellan to measure the relationship between AGN obscuration and accretion activity over the bulk of cosmic history. This work will establish the prominence of both obscured and unobscured growth phases of black holes and shed light on the processes that trigger and fuel AGN as a function of time. We will complete three complementary projects that focus on a) understanding the completeness and biases of AGN selection at mid-IR versus X-ray wavelengths, b) tracing optical obscuration as a function of luminosity and redshift, and c) measuring the distribution and evolution of X-ray absorption of AGN. We will undertake a study of AGN demographics comparing selection techniques at three different wavelengths: mid-IR selection using data from the Spitzer Space Telescope, X- ray selection using data from the XMM-Newton and Chandra satellites, and broad-line optical selection using PRIMUS spectroscopy. We will determine the overlap and uniqueness of samples created using each method, to quantify the completeness and biases inherent in AGN selection at each wavelength. This will lead to a constraint on the fraction of heavily obscured, Compton-thick AGN to z~1. To study the optical obscuration of AGN, we will use three recently-completed spectroscopic surveys -- PRIMUS, DEEP2, and our own Keck program -- to robustly determine the ratio of unobscured (broad-line) to obscured (non--broad-line) X-ray selected AGN as a function of luminosity from z~0.2 to z~3. We will utilize the well- understood selection functions and characterize the AGN completeness of each survey as a function of redshift, magnitude, and obscuration properties. This will allow us to correct for a variety of observational effects to measure the underlying joint redshift- and luminosity-dependence of optical obscuration, which has direct implications

  11. The Angular Clustering of WISE-Selected AGN: Different Haloes for Obscured and Unobscured AGN

    NASA Astrophysics Data System (ADS)

    Yan, Lin

    2015-08-01

    We calculate the angular correlation function for a sample of 170,000 AGN extracted from the Wide-field Infrared Survey Explorer (WISE) catalog, selected to have red mid-IR colors (W1 - W2 > 0.8) and 4.6 micron flux densities brighter than 0.14 mJy). The sample is expected to be >90% reliable at identifying AGN, and to have a mean redshift of z=1.1. In total, the angular clustering of WISE-AGN is roughly similar to that of optical AGN. We cross-match these objects with the photometric SDSS catalog and distinguish obscured sources with (r - W2) > 6 from bluer, unobscured AGN. Obscured sources present a higher clustering signal than unobscured sources. Since the host galaxy morphologies of obscured AGN are not typical red sequence elliptical galaxies and show disks in many cases, it is unlikely that the increased clustering strength of the obscured population is driven by a host galaxy segregation bias. By using relatively complete redshift distributions from the COSMOS survey, we find obscured sources at mean redshift z=0.9 have a bias of b = 2.9 \\pm 0.6 and are hosted in dark matter halos with a typical mass of log(M/M_odot)~13.5. In contrast, unobscured AGN at z~1.1 have a bias of b = 1.6 \\pm 0.6 and inhabit halos of log(M/M_odot)~12.4. These findings suggest that obscured AGN inhabit denser environments than unobscured AGN, and are difficult to reconcile with the simplest AGN unification models, where obscuration is driven solely by orientation.

  12. Neutrinos from AGN

    NASA Technical Reports Server (NTRS)

    Kazanas, Demosthenes; White, Nicholas E. (Technical Monitor)

    2000-01-01

    The great penetrating power of neutrinos makes them ideal probe of astrophysical sites and conditions inaccessible to other forms of radiation. These are the centers of stars (collapsing or not) and the centers of Active Galactic Nuclei (AGN). It has been suggested that AGN presented a very promising source of high energy neutrinos, possibly detectable by underwater neutrino detectors. This paper reviews the evolution of ideas concerning the emission of neutrinos from AGN in view of the more recent developments in gamma-ray astronomy and their implications for the neutrino emission from these class of objects.

  13. Carbon, Nitrogen, and Phosphorus Increase in Soil Physical Fractions Following Vegetation Change from Grassland to Woodland

    NASA Astrophysics Data System (ADS)

    Kantola, I. B.; Boutton, T. W.; Filley, T. R.; Hallmark, C. T.

    2009-12-01

    Woody plant encroachment has been pervasive in grass-dominated ecosystems around the world during the past century due to livestock grazing, fire suppression, and/or changes in climate and atmospheric chemistry. In the Rio Grande Plains of Texas, subtropical thorn woodlands dominated by N-fixing tree legumes have largely replaced grasslands. This dramatic land cover change has increased above- and belowground primary productivity and accelerated rates of biogeochemical processes in the soil. The purpose of this study was to assess the impact of this grassland to woodland transition on C, N, and P concentrations in soil physical fractions that differ in turnover rates. Soil samples (0-10 cm) were collected in remnant grasslands and near the centers of woody plant clusters ranging in age from 15 to 90 yrs in a subtropical savanna parkland in southern Texas. Soils were fractionated by wet sieving into five size and density classes: un-sieved whole soil, free light fraction (density <1 g/cm3), macroaggregates (>250 µm), microaggregates (53-250 µm), and free silt and clay (<53 µm). C and N concentrations in each of the fractions were determined by elemental analysis, and total P concentrations were determined by alkaline oxidation and sulfuric acid digestion coupled with ascorbic acid colorimetry. C, N, and P concentrations in whole soil were 2-3X greater in woody clusters than in grasslands. In addition, C, N, and P concentrations all increased linearly with time following woody plant invasion in all fractions except free silt and clay. Most of the newly accrued C, N, and P was in the relatively more labile light fractions and macroaggregates. C:P and N:P ratios increased following woody encroachment, indicating carbon and nitrogen accumulated at a faster rate than phosphorus. Since N and P are generally the most limiting nutrients in terrestrial ecosystems, increased stores of these elements are likely to alter rates of microbial processes, plant-microbe and plant

  14. Three years of Swift/BAT Survey of AGN: Reconciling Theory and Observations?

    SciTech Connect

    Burlon, D.; Ajello, M.; Greiner, J.; Comastri, A.; Merloni, A.; Gehrels, N.; /NASA, Goddard

    2011-02-07

    It is well accepted that unabsorbed as well as absorbed AGN are needed to explain the nature and the shape of the Cosmic X-ray background, even if the fraction of highly absorbed objects (dubbed Compton-thick sources) substantially still escapes detection. We derive and analyze the absorption distribution using a complete sample of AGN detected by Swift-BAT in the first three years of the survey. The fraction of Compton-thick AGN represents only 4.6% of the total AGN population detected by Swift-BAT. However, we show that once corrected for the bias against the detection of very absorbed sources the real intrinsic fraction of Compton-thick AGN is 20{sub -6}{sup +9}%. We proved for the first time (also in the BAT band) that the anti-correlation of the fraction of absorbed AGN and luminosity it tightly connected to the different behavior of the luminosity functions (XLFs) of absorbed and unabsorbed AGN. This points towards a difference between the two subsamples of objects with absorbed AGN being, on average, intrinsically less luminous than unobscured ones. Moreover the XLFs show that the fraction of obscured AGN might also decrease at very low luminosity. This can be successfully interpreted in the framework of a disk cloud outflow scenario as the disappearance of the obscuring region below a critical luminosity. Our results are discussed in the framework of population synthesis models and the origin of the Cosmic X-ray Background.

  15. Completing the AGN Census for Nearby Galaxies (Archival Component)

    NASA Astrophysics Data System (ADS)

    Ho, Luis

    2010-09-01

    The census of AGNs in the local Universe provides an efficient and effective estimate of the occupation fraction of central black holes in galaxies. While the demographics of AGNs in bulge-dominated systems is fairly well known, the situation in later-type galaxies is still murky because of potential optical selection biases. Searching for X-ray cores using Chandra can bypass these complications. We propose to complete the local AGN census by surveying all 188 star-forming (H II) nuclei in the well-studied Palomar sample of nearby galaxies. We request funding to analyze the 85 objects already in the archive; new observations have been proposed for the rest. We will establish with unprecedented reliability the AGN fraction across a wide range in Hubble type and Eddington ratios.

  16. Properties of galaxies around AGNs with the most massive supermassive black holes revealed by clustering analysis

    NASA Astrophysics Data System (ADS)

    Shirasaki, Yuji; Komiya, Yutaka; Ohishi, Masatoshi; Mizumoto, Yoshihiko

    2016-04-01

    We present results of the clustering analysis between active galactic nuclei (AGNs) and galaxies at redshift 0.1-1.0, which was performed to investigate the properties of galaxies associated with the AGNs and reveal the nature of the fueling mechanism of supermassive black holes (SMBHs). We used 8059 AGNs/quasi-stellar objects (QSOs) for which virial masses of individual SMBHs were measured, and divided them into four mass groups.Cross-correlation analysis was performed to reconfirm our previous result that cross-correlation length increases with SMBH mass MBH; we obtained consistent results. A linear bias of AGN for each mass group was measured as 1.47 for MBH = 107.5-108.2 M⊙ and 3.08 for MBH = 109-1010 M⊙. The averaged color and luminosity distributions of galaxies around the AGNs/QSOs were also derived for each mass group. The galaxy color Dopt-IR was estimated from a spectral energy distribution (SED) constructed from a catalog derived by merging the Sloan Digital Sky Survey (SDSS) and the UKIRT Infrared Deep Sky Survey (UKIDSS) catalogs. The distributions of color and luminosity were derived by a subtraction method, which does not require redshift information of galaxies. The main results of this work are as follows. (1) A linear bias increases by a factor of two from the lower-mass group to the highest-mass group. (2) The environment around AGNs with the most massive SMBHs (MBH > 109 M⊙) is dominated by red sequence galaxies. (3) Marginal indication of decline in luminosity function at dimmer side of MIR > -19.5 is found for galaxies around AGNs with MBH = 108.2-109 M⊙ and nearest redshift group (z = 0.1-0.3). These results indicate that AGNs with the most massive SMBHs reside in haloes where a large fraction of galaxies have been transited to the red sequence. The accretion of hot halo gas as well as recycled gas from evolving stars can be one of the plausible mechanisms to fuel the SMBHs above ˜ 109 M⊙.

  17. A multi-wavelength survey of AGN in massive clusters: AGN distribution and host galaxy properties

    NASA Astrophysics Data System (ADS)

    Klesman, Alison J.; Sarajedini, Vicki L.

    2014-07-01

    We investigate the effect of environment on the presence and fuelling of active galactic nuclei (AGN) by identifying galaxies hosting AGN in massive galaxy clusters and the fields around them. We have identified AGN candidates via optical variability (178), X-ray emission (74), and mid-IR SEDs (64) in multi-wavelength surveys covering regions centred on 12 galaxy clusters at redshifts 0.5 < z < 0.9. In this paper, we present the radial distribution of AGN in clusters to examine how local environment affects the presence of an AGN and its host galaxy. While distributions vary from cluster to cluster, we find that the radial distribution of AGN generally differs from that of normal galaxies. X-ray-selected AGN candidates appear to be more centrally concentrated than normal galaxies in the inner 20 per cent of the virial radius, while becoming less centrally concentrated in the outer regions. Mid-IR-selected AGN are less centrally concentrated overall. Optical variables have a similar distribution to normal galaxies in the inner regions, then become somewhat less centrally concentrated farther from the cluster centre. The host galaxies of AGN reveal a different colour distribution than normal galaxies, with many AGN hosts displaying galaxy colours in the `green valley' between the red sequence and blue star-forming normal galaxies. This result is similar to those found in field galaxy studies. The colour distribution of AGN hosts is more pronounced in disturbed clusters where minor mergers, galaxy harassment, and interactions with cluster substructure may continue to prompt star formation in the hosts. Among normal galaxies, we find that galaxy colours become generally bluer with increasing cluster radius, as is expected. However, we find no relationship between host galaxy colour and cluster radius among AGN hosts, which may indicate that processes related to the accreting supermassive black hole have a greater impact on the star-forming properties of the host galaxy

  18. Radio Loudness of AGNs: Host Galaxy Morphology and the Spin Paradigm

    SciTech Connect

    Stawarz, L.; Sikora, M.; Lasota, J.-P.

    2007-10-15

    We investigate how the total radio luminosity of AGN-powered radio sources depends on their accretion luminosity and the central black hole mass. We find that AGNs form two distinct and well separated sequences on the radio-loudness -- Eddington-ratio plane. We argue that these sequences mark the real upper bounds of radio-loudness of two distinct populations of AGNs: those hosted respectively by elliptical and disk galaxies. Both sequences show the same dependence of the radio-loudness on the Eddington ratio (an increase with decreasing Eddington ratio), which suggests that another parameter in addition to the accretion rate must play a role in determining the jet production efficiency in active galactic nuclei, and that this parameter is related to properties of the host galaxy. The revealed host-related radio dichotomy breaks down at high accretion rates where the dominant fraction of luminous quasars hosted by elliptical galaxies is radio quiet. We argue that the huge difference between the radio-loudness reachable by AGNs in disc and elliptical galaxies can be explained by the scenario according to which the spin of a black hole determines the outflows power, and central black holes can reach large spins only in early type galaxies (following major mergers), and not (in a statistical sense) in spiral galaxies.

  19. Host Galaxy Properties of the Swift BAT Ultra Hard X-Ray Selected AGN

    NASA Technical Reports Server (NTRS)

    Koss, Michael; Mushotzky, Richard; Veilleux, Sylvain; Winter, Lisa M.; Baumgartner, Wayne; Tueller, Jack; Gehrels, Neil; Valencic, Lynne

    2011-01-01

    We have assembled the largest sample of ultra hard X-ray selected (14-195 keV) AGN with host galaxy optical data to date, with 185 nearby (z<0.05), moderate luminosity AGN from the Swift Burst Alert Telescope (BAT) sample. The BAT AGN host galaxies have intermediate optical colors (u -- r and g -- r) that are bluer than a comparison sample of inactive galaxies and optically selected AGN from the Sloan Digital Sky Survey (SDSS) which are chosen to have the same stellar mass. Based on morphological classifications from the RC3 and the Galaxy Zoo, the bluer colors of BAT AGN are mainly due to a higher fraction of mergers and massive spirals than in the comparison samples. BAT AGN in massive galaxies (log Stellar Mass >10.5) have a 5 to 10 times higher rate of spiral morphologies than in SDSS AGN or inactive galaxies. We also see enhanced far-IR emission in BAT AGN suggestive of higher levels of star formation compared to the comparison samples. BAT AGN are preferentially found in the most massive host galaxies with high concentration indexes indicative of large bulge-to-disk ratios and large supermassive black holes. The narrow-line (NL) BAT AGN have similar intrinsic luminosities as the SDSS NL Seyferts based on measurements of [O III] Lambda 5007. There is also a correlation between the stellar mass and X-ray emission. The BAT AGN in mergers have bluer colors and greater ultra hard X-ray emission compared to the BAT sample as whole. In agreement with the Unified Model of AGN, and the relatively unbiased nature of the BAT sources, the host galaxy colors and morphologies are independent of measures of obscuration such as X-ray column density or Seyfert type. The high fraction of massive spiral galaxies and galaxy mergers in BAT AGN suggest that host galaxy morphology is related to the activation and fueling of local AGN.

  20. Increased susceptibility to oxidation of vitamin E in mitochondrial fractions compared with synaptosomal fractions from rat brains.

    PubMed

    Vatassery, G T; Smith, W E; Quach, H T

    1994-01-01

    The in vitro oxidation of vitamin E (alpha tocopherol) in rat brain synaptosomes and mitochondria by 2,2'-azo-bis-(2'-amidinopropane) dihydrochloride (ABAPH), a free radical generator, was studied. Subcellular fractions (300 micrograms total protein) were suspended in different buffers at pH 7.4 and incubated at 37 degrees C. In the presence of 0.5 mM ABAPH the mitochondrial alpha tocopherol began to get oxidized after a lag time or induction time of 15 min compared with a lag time of 30 min for the synaptosomal fraction. Thus the reserve of reducing compounds that are responsible for delaying tocopherol oxidation is less in mitochondria than in synaptosomes. More tocopherolquinone was produced during incubations without ABAPH compared with incubations in the presence of ABAPH suggesting that the mechanism of oxidation of tocopherol differs under these two conditions. When mitochondria were incubated in buffer without oxidants the production of tocopherolquinone preceded that of thiobarbituric acid reactive substances, an indicator of peroxidation of fatty acids. Therefore, alpha tocopherol is active as an anti-oxidant in mitochondrial membranes and the production of alpha tocopherolquinone could be a monitor of mild membrane oxidation under in vitro conditions. The ease of oxidation of mitochondrial tocopherol suggests a general vulnerability of the mitochondrial membranes to oxidation. Adding vitamin E or its water soluble analogs during in vitro experiments may improve the stability and viability of mitochondria. Furthermore, antioxidant protection by vitamin E may be crucial for the maintenance of tissues, such as brain, whose function is critically dependent upon the availability of high energy phosphates.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8130733

  1. The bulge-disc decomposition of AGN host galaxies

    NASA Astrophysics Data System (ADS)

    Bruce, V. A.; Dunlop, J. S.; Mortlock, A.; Kocevski, D. D.; McGrath, E. J.; Rosario, D. J.

    2016-05-01

    We present the results from a study of the morphologies of moderate luminosity X-ray-selected active galactic nuclei (AGN) host galaxies in comparison to a carefully mass-matched control sample at 0.5 < z < 3 in the CANDELS GOODS-S field. We apply a multiwavelength morphological decomposition analysis to these two samples and report on the differences between the morphologies as fitted from single Sérsic and multiple Sérsic models, and models which include an additional nuclear point-source component. Thus, we are able to compare the widely adopted single Sérsic fits from previous studies to the results from a full morphological decomposition, and address the issue of how biased the inferred properties of AGN hosts are by a potential nuclear contribution from the AGN itself. We find that the AGN hosts are indistinguishable from the general galaxy population except that beyond z ≃ 1.5 they have significantly higher bulge fractions. Even including nuclear sources in our modelling, the probability of this result arising by chance is ˜1 × 10-5, alleviating concerns that previous, purely single Sérsic, analyses of AGN hosts could have been spuriously biased towards higher bulge fractions. This data set also allows us to further probe the physical nature of these point-source components; we find no strong correlation between the point-source component and AGN activity. Our analysis of the bulge and disc fractions of these AGN hosts in comparison to a mass-matched control sample reveals a similar morphological evolutionary track for both the active and non-active populations, providing further evidence in favour of a model where AGN activity is triggered by secular processes.

  2. Nitrogen Isotope Fractionation Increases with the Cell-Specific Dissimilatory Nitrate Reduction Rate

    NASA Astrophysics Data System (ADS)

    Kritee, K.; Sigman, D. M.; Granger, J.

    2009-12-01

    The use of the nitrogen (N) isotopes to estimate the impacts and rates of different N transformations depends on knowledge of their extent of isotope fractionation under environmentally relevant physico-chemical conditions. Though the extent of N isotope fractionation during denitrification by pure cultures of bacteria has been determined in the past, relatively large variation in the isotope effect during apparently replicate experiments has been perplexing and the values that should be most relevant for environmental applications have not been clear. We measured the extent of N and O isotope fractionation during nitrate reduction by two bacterial denitrifiers, Pseudomonas chlororaphis ATCC 43928 and Paracoccus denitrificans ATCC 19367 that were grown in 1L batch reactors in the presence of differing carbon sources that included complex organic (e.g, bactopeptone and casein) or defined (e.g., glucose and acetate) carbon compounds and varying concentrations of dissolved oxygen (0 - 4 mM) and nitrate (25 - 800 mM) in the assay medium. For P. denitrificans and P. Chlororaphis , the total range of the N isotope effect (15ɛ) varied from 22.3 to 9.3 ‰ and 34.3 to 15.6 ‰, respectively. Despite this large variation, the O-to-N isotope effect ratio centered around 1, consistent with our previous work. A systematic pattern that has emerged from these studies is that the N and O isotope effect during denitrification increases with increasing cell specific nitrate reduction (CSNR) rate. This sense of variation runs counter to expectations from studies of carbon and sulfur isotope effects during methanogenesis and sulfate reduction, respectively, in which higher substrate consumption rates are associated with lower isotope effects. As with many multi-step microbial processes, variability in the dissimilatory nitrate reduction isotope effect may arise from variation in the “relative” rate and reversibility of (1) nitrate uptake into the denitrifying cell, and/or (2

  3. Black hole growth and starburst activity at z = 0.6-4 in the Chandra Deep Field South. Host galaxies properties of obscured AGN

    NASA Astrophysics Data System (ADS)

    Brusa, M.; Fiore, F.; Santini, P.; Grazian, A.; Comastri, A.; Zamorani, G.; Hasinger, G.; Merloni, A.; Civano, F.; Fontana, A.; Mainieri, V.

    2009-12-01

    Aims: The co-evolution of host galaxies and the active black holes which reside in their centre is one of the most important topics in modern observational cosmology. Here we present a study of the properties of obscured active galactic nuclei (AGN) detected in the CDFS 1 Ms observation and their host galaxies. Methods: We limited the analysis to the MUSIC area, for which deep K-band observations obtained with ISAAC@VLT are available, ensuring accurate identifications of the counterparts of the X-ray sources as well as reliable determination of photometric redshifts and galaxy parameters, such as stellar masses and star formation rates. In particular, we: 1) refined the X-ray/infrared/optical association of 179 sources in the MUSIC area detected in the Chandra observation; 2) studied the host galaxies observed and rest frame colors and properties. Results: We found that X-ray selected (LX ⪆ 1042 erg s-1) AGN show Spitzer colors consistent with both AGN and starburst dominated infrared continuum; the latter would not have been selected as AGN from infrared diagnostics. The host galaxies of X-ray selected obscured AGN are all massive (Mast > 1010 M_⊙) and, in 50% of the cases, are also actively forming stars (1/SSFR < tHubble) in dusty environments. The median L/LEdd value of the active nucleus is between 2% and 10% depending on the assumed MBH/Mast ratio. Finally, we found that the X-ray selected AGN fraction increases with the stellar mass up to a value of 30% at z > 1 and Mast > 3 × 1011 M_⊙, a fraction significantly higher than in the local Universe for AGN of similar luminosities. Tables [see full textsee full textsee full text] and [see full textsee full textsee full text] are only available in electronic form at http://www.aanda.org

  4. Star Formation and AGN Activity in Galaxy Clusters from z=1-2: a Multi-Wavelength Analysis Featuring Herschel/PACS

    NASA Astrophysics Data System (ADS)

    Alberts, Stacey; Pope, Alexandra; Brodwin, Mark; Chung, Sun Mi; Cybulski, Ryan; Dey, Arjun; Eisenhardt, Peter R. M.; Galametz, Audrey; Gonzalez, Anthony H.; Jannuzi, Buell T.; Stanford, S. Adam; Snyder, Gregory F.; Stern, Daniel; Zeimann, Gregory R.

    2016-07-01

    We present a detailed, multi-wavelength study of star formation (SF) and active galactic nucleus (AGN) activity in 11 near-infrared (IR) selected, spectroscopically confirmed massive (≳1014 M ⊙) galaxy clusters at 1 < z < 1.75. Using new deep Herschel/PACS imaging, we characterize the optical to far-IR spectral energy distributions (SEDs) for IR-luminous cluster galaxies, finding that they can, on average, be well described by field galaxy templates. Identification and decomposition of AGNs through SED fittings allows us to include the contribution to cluster SF from AGN host galaxies. We quantify the star-forming fraction, dust-obscured SF rates (SFRs) and specific SFRs for cluster galaxies as a function of cluster-centric radius and redshift. In good agreement with previous studies, we find that SF in cluster galaxies at z ≳ 1.4 is largely consistent with field galaxies at similar epochs, indicating an era before significant quenching in the cluster cores (r < 0.5 Mpc). This is followed by a transition to lower SF activity as environmental quenching dominates by z ∼ 1. Enhanced SFRs are found in lower mass (10.1\\lt {log} {M}\\star /{M}ȯ \\lt 10.8) cluster galaxies. We find significant variation in SF from cluster to cluster within our uniformly selected sample, indicating that caution should be taken when evaluating individual clusters. We examine AGNs in clusters from z = 0.5–2, finding an excess AGN fraction at z ≳ 1, suggesting environmental triggering of AGNs during this epoch. We argue that our results—a transition from field-like to quenched SF, enhanced SF in lower mass galaxies in the cluster cores, and excess AGNs—are consistent with a co-evolution between SF and AGNs in clusters and an increased merger rate in massive halos at high redshift.

  5. SWIFT Observations AGN

    NASA Technical Reports Server (NTRS)

    Mushotzky, Richard

    2008-01-01

    I will present results from the x-ray and optical follow-up observations of the Swift Burst Alert Telescope (BAT) Active Galactic Nuclei (AGN) survey. I will discuss the nature of obscuration in these objects, the relationship to optical properties and the change of properties with luminosity and galaxy type.

  6. Uncovering AGN Fueling and Feedback in Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    Mushotzky, Richard

    2014-09-01

    While massive black holes (BHs) are ubiquitous in massive galaxies, their presence in dwarf galaxies is less certain. This constitutes a major gap in our understanding of BH-galaxy co-evolution. Identifying low-mass BHs in local dwarfs could also constrain BH seed formation at high z. Active BHs in dwarfs can reveal BH fueling and feedback in a vastly different regime than the well-studied AGN in massive hosts. Most AGN feedback models focus on the latter, as star formation is thought to suffice to drive feedback in dwarfs. However, AGN are increasingly found in dwarfs, where their effect on hosts may be most dramatic. We propose an unprecedented program to detect and characterize AGN fueling and feedback in the low-mass regime, using a unique sample of Swift-BAT AGN in dwarf

  7. Enlarged Thalamic Volumes and Increased Fractional Anisotropy in the Thalamic Radiations in Veterans with Suicide Behaviors

    PubMed Central

    Lopez-Larson, Melissa; King, Jace B.; McGlade, Erin; Bueler, Elliott; Stoeckel, Amanda; Epstein, Daniel J.; Yurgelun-Todd, Deborah

    2013-01-01

    Post-mortem studies have suggested a link between the thalamus, psychiatric disorders, and suicide. We evaluated the thalamus and anterior thalamic radiations (ATR) in a group of Veterans with and without a history of suicidal behavior (SB) to determine if thalamic abnormalities were associated with an increased risk of SB. Forty Veterans with mild traumatic brain injury (TBI) and no SB (TBI-SB), 19 Veterans with mild TBI and a history of SB (TB + SB), and 15 healthy controls (HC) underwent magnetic resonance imaging scanning including a structural and diffusion tensor imaging scan. SBs were evaluated utilizing the Columbia Suicide Rating Scale and impulsivity was measured using the Barratt Impulsiveness Scale (BIS). Differences in thalamic volumes and ATR fractional anisotropy (FA) were examined between (1) TBI + SB versus HC and (2) TBI + SB versus combined HC and TBI-SB and (3) between TBI + SB and TBI-SB. Left and right thalamic volumes were significantly increased in those with TBI + SB compared to the HC, TBI-SB, and the combined group. Veterans with TBI + SB had increased FA bilaterally compared to the HC, HC and TBI-SB group, and the TBI-SB only group. Significant positive associations were found for bilateral ATR and BIS in the TBI + SB group. Our findings of thalamic enlargement and increased FA in individuals with TBI + SB suggest that this region may be a biomarker for suicide risk. Our findings are consistent with previous evidence indicating that suicide may be associated with behavioral disinhibition and frontal-thalamic-limbic dysfunction and suggest a neurobiologic mechanism that may increase vulnerability to suicide. PMID:23964245

  8. The PEP survey: infrared properties of radio-selected AGN

    NASA Astrophysics Data System (ADS)

    Magliocchetti, M.; Lutz, D.; Rosario, D.; Berta, S.; Le Floc'h, E.; Magnelli, B.; Pozzi, F.; Riguccini, L.; Santini, P.

    2014-07-01

    By exploiting the VLA-COSMOS and the Herschel-PEP surveys, we investigate the far-infrared (FIR) properties of radio-selected AGN. To this purpose, from VLA-COSMOS we considered the 1537, F1.4 GHz ≥ 0.06 mJy sources with a reliable redshift estimate, and sub-divided them into star-forming galaxies and AGN solely on the basis of their radio luminosity. The AGN sample is complete with respect to radio selection at all z ≲ 3.5. 832 radio sources have a counterpart in the PACS Evolutionary Probe catalogue. 175 are AGN. Their redshift distribution closely resembles that of the total radio-selected AGN population, and exhibits two marked peaks at z ˜ 0.9 and 2.5. We find that the probability for a radio-selected AGN to be detected at FIR wavelengths is both a function of radio power and redshift, whereby powerful sources are more likely to be FIR emitters at earlier epochs. This is due to two distinct effects: (1) at all radio luminosities, FIR activity monotonically increases with look-back time and (2) radio activity of AGN origin is increasingly less effective at inhibiting FIR emission. Radio-selected AGN with FIR emission are preferentially located in galaxies which are smaller than those hosting FIR-inactive sources. Furthermore, at all z ≲ 2, there seems to be a preferential (stellar) mass scale M* ˜ [1010-1011] M⊙ which maximizes the chances for FIR emission. We find such FIR (and mid-infrared) emission to be due to processes indistinguishable from those which power star-forming galaxies. It follows that radio emission in at least 35 per cent of the entire AGN population is the sum of two contributions: AGN accretion and star-forming processes within the host galaxy.

  9. Neutral hydrogen in galaxy clusters: impact of AGN feedback and implications for intensity mapping

    NASA Astrophysics Data System (ADS)

    Villaescusa-Navarro, Francisco; Planelles, Susana; Borgani, Stefano; Viel, Matteo; Rasia, Elena; Murante, Giuseppe; Dolag, Klaus; Steinborn, Lisa K.; Biffi, Veronica; Beck, Alexander M.; Ragone-Figueroa, Cinthia

    2016-03-01

    By means of zoom-in hydrodynamic simulations, we quantify the amount of neutral hydrogen (H I) hosted by groups and clusters of galaxies. Our simulations, which are based on an improved formulation of smoothed particle hydrodynamics, include radiative cooling, star formation, metal enrichment and supernova feedback, and can be split into two different groups, depending on whether feedback from active galactic nuclei (AGN) is turned on or off. Simulations are analysed to account for H I self-shielding and the presence of molecular hydrogen. We find that the mass in neutral hydrogen of dark matter haloes monotonically increases with the halo mass and can be well described by a power law of the form M_{H I}(M,z)∝ M^{3/4}. Our results point out that AGN feedback reduces both the total halo mass and its H I mass, although it is more efficient in removing H I. We conclude that AGN feedback reduces the neutral hydrogen mass of a given halo by ˜50 per cent, with a weak dependence on halo mass and redshift. The spatial distribution of neutral hydrogen within haloes is also affected by AGN feedback, whose effect is to decrease the fraction of H I that resides in the halo inner regions. By extrapolating our results to haloes not resolved in our simulations, we derive astrophysical implications from the measurements of Ω _{H I}(z): haloes with circular velocities larger than ˜25 km s-1 are needed to host H I in order to reproduce observations. We find that only the model with AGN feedback is capable of reproducing the value of Ω _{H I}b_{H I} derived from available 21 cm intensity mapping observations.

  10. Interpreting the IR SED of z~0.3-2.8 IR-Luminous Galaxies and AGN Using Hydrodynamic Simulations

    NASA Astrophysics Data System (ADS)

    Roebuck, Eric John; Sajina, Anna; Hayward, Christopher C.; Pope, Alexandra; Kirkpatrick, Allison; Hernquist, Lars E.; Yan, Lin

    2016-01-01

    We use three-dimensional hydrodynamical galaxy merger simulations to further investigate the nature of a sample of 342 24 μm-selected (ultra) luminous infrared galaxies at z~0.3-2.8. All of our sources have low-resolution Spitzer/IRS spectra -- the largest such sample outside the local universe. These spectra allow us to determine that our sample consists of a mixture of star forming galaxies (SFGs), AGN, and composites. We address the question of how well do empirical IR AGN fraction estimates trace the intrinsic AGN fraction (i.e. the AGN-to-total power in the galaxy prior to dust re-processing), including how they relate to galaxy properties such as merger stage, dust/gas content, and star formation rates. We do this by fitting the observed SEDs of our sample with theoretical SEDs based on GADGET hydrodynamic merger simulations additionally processed through the SUNRISE radiative transfer code. We additionally investigate systematic uncertainties associated with these quantities using the goodness of fits to our model library. The key findings are: 1) our simulation-based fits are in broad agreement with the empirical model-based fits, 2) much of the AGN fraction of LIR is missed if the AGN's contribution to heating the host galaxy dust is not accounted for, and 3) the IR AGN fraction traces the intrinsic AGN fraction up to the coalescence stage, however may underestimate the intrinsic AGN fraction post coalescence.

  11. Creatine kinase B deficient neurons exhibit an increased fraction of motile mitochondria

    PubMed Central

    Kuiper, Jan WP; Oerlemans, Frank TJJ; Fransen, Jack AM; Wieringa, Bé

    2008-01-01

    Background Neurons require an elaborate system of intracellular transport to distribute cargo throughout axonal and dendritic projections. Active anterograde and retrograde transport of mitochondria serves in local energy distribution, but at the same time also requires input of ATP. Here we studied whether brain-type creatine kinase (CK-B), a key enzyme for high-energy phosphoryl transfer between ATP and CrP in brain, has an intermediary role in the reciprocal coordination between mitochondrial motility and energy distribution. Therefore, we analysed the impact of brain-type creatine kinase (CK-B) deficiency on transport activity and velocity of mitochondria in primary murine neurons and made a comparison to the fate of amyloid precursor protein (APP) cargo in these cells, using live cell imaging. Results Comparison of average and maximum transport velocities and global transport activity showed that CK-B deficiency had no effect on speed of movement of mitochondria or APP cargo, but that the fraction of motile mitochondria was significantly increased by 36% in neurons derived from CK-B knockout mice. The percentage of motile APP vesicles was not altered. Conclusion CK-B activity does not directly couple to motor protein activity but cells without the enzyme increase the number of motile mitochondria, possibly as an adaptational strategy aimed to enhance mitochondrial distribution versatility in order to compensate for loss of efficiency in the cellular network for ATP distribution. PMID:18662381

  12. A toxic fraction from scolopendra venom increases the basal release of neurotransmitters in the ventral ganglia of crustaceans.

    PubMed

    Gutiérrez, María del Carmen; Abarca, Carolina; Possani, Lourival D

    2003-06-01

    A toxic fraction from centipede (Scolopendra sp.) venom was tested in neurotransmitter release experiments. The venom was fractionated by DEAE-cellulose with a linear gradient from 20 mM to 1.0 M of ammonium acetate pH 4.7. Lethality tests were performed by injections into the third abdominal dorsolateral segment of sweet water crayfishes of the species Cambarellus cambarellus. Only fraction V (TF) was toxic. Analysis by SDS-PAGE showed that this fraction contains at least seven proteins. It induces an increase of basal gamma-amino butyric acid (GABA) and glutamate release from ventral abdominal ganglia of C. cambarellus. Assays conducted with this fraction in the presence of several drugs that affect ion channel function suggested that TF modifies membrane permeability by increasing basal release of neurotransmitters was very likely through sodium channels. PMID:12860060

  13. Toward a Unified AGN Structure

    NASA Technical Reports Server (NTRS)

    Kazanas, Demosthenes; Fukumura, Keigo; Shrader, Chris; Behar, Ehud; Contopoulosa, Ioannis

    2012-01-01

    We present a unified model for the structure and appearance of accretion powered sources across their entire luminosity range from galactic X-ray binaries (XRB) to luminous quasars, with emphasis on AG N and their phenomenology. Central to this model is the notion of MHD winds launched by the accretion disks that power these objects. These winds provide the matter that manifests as blueshifted absorption features in the UV and X-ray spectra of a large fraction of these sources; furthermore, their density distribution in the poloidal plane determines their "appearance" (i.e. the column and velocity structure of these absorption features and the obscuration of the continuum source) as a function of the observer inclination angle (a feature to which INTEGRAL has made significant contributions). This work focuses on just the broadest characteristics of these objects; nonetheless, it provides scaling laws that allow one to reproduce within this model the properties of objects extending in luminosity from luminous quasars to XRBs. Our general conclusion is that the AGN phenomenology can be accounted for in terms of three parameters: The wind maSS flux in units of the Eddington value, m(dot), the observers' inclination angle Theta and the logarithmic slope between the 0/UV and X-ray fluxes alpha(sub ox); however because of a correlation between alpha(sub ox) and UV luminosity the number of significant parameters is two. The AGN correlations implied by this model appear to extend to and consistent with the XRB phenomenology, suggesting the presence of a truly unified underlying structure for accretion powered sources.

  14. Predictors of Increased Left Ventricular Filling Pressure in Dialysis Patients with Preserved Left Ventricular Ejection Fraction

    PubMed Central

    Bajraktari, Gani; Berbatovci-Ukimeraj, Mimoza; Hajdari, Ali; Ibraimi, Lavdim; Daullxhiu, Irfan; Elezi, Ymer; Ndrepepa, Gjin

    2009-01-01

    Aim To study the left and right ventricular function and to assess the predictors of increased left ventricular (LV) filling pressure in dialysis patients with preserved LV ejection fraction. Methods This study included 63 consecutive patients (age 57 ± 14 years, 57% women) with end-stage renal failure. Echocardiography, including tissue Doppler measurements, was performed in all patients. Based on the median value of the ratio of transmitral early diastolic velocity to early myocardial velocity (E/E’ ratio), patients were divided into 2 groups: the group with high filling pressure (E/E’>10.16) and the group with low filling pressure (E/E’≤10.16). Results Compared with patients with low filling pressure, the group of patients with high filling pressure included a higher proportion of diabetic patients (41% vs 13%, P = 0.022) and had greater LV mass index (211 ± 77 vs 172 ± 71 g/m3, P = 0.04), lower LV lateral long axis amplitude (1.4 ± 0.3 vs 1.6 ± 0.3 cm, P = 0.01), higher E wave (84 ± 19 vs 64 ± 18cm/s, P < 0.001), lower systolic myocardial velocity (S’:8.6 ± 1.5 vs 7.0 ± 1.3 cm/s, P < 0.001), and lower diastolic myocardial velocities (E’: 6.3 ± 1.9 vs 9.5 ± 2.9 cm/s, P < 0.001; A’: 8.4 ± 1.9 vs 9.7 ± 2.5 cm/s, P = 0.018). Multivariate analysis identified LV systolic myocardial velocity – S’ wave (adjusted odds ratio, 1.909; 95% confidence interval, 1.060-3.439; P = 0.031) and age (1.053; 1.001-1.108; P = 0.048) as the only independent predictors of high LV filling pressure in dialysis patients. Conclusions In dialysis patients with preserved left ventricular ejection fraction, reduced systolic myocardial velocity and elderly age are independent predictors of increased left ventricular filling pressure. PMID:20017222

  15. Ionized Absorbers in AGN

    NASA Astrophysics Data System (ADS)

    Mathur, S.

    1999-08-01

    As a part of this program, we observed three AGN:PKS2251 + 113, PG0043 = 039 and PLH909. Two objects show signatures of absorbtion in their UV spectra. Based on our earlier modeling of X-ray warm absorbents, we expected to observe X-ray observation in these objects. The third, PLH909, is known to have soft excess in EINSTEIN data. Attachment: "Exploratory ASCA observation of broad absorption line quasi-stellar objects".

  16. Ionized Absorbers in AGN

    NASA Technical Reports Server (NTRS)

    Mathur, S.

    1999-01-01

    As a part of this program, we observed three AGN:PKS2251 + 113, PG0043 = 039 and PLH909. Two objects show signatures of absorbtion in their UV spectra. Based on our earlier modeling of X-ray warm absorbents, we expected to observe X-ray observation in these objects. The third, PLH909, is known to have soft excess in EINSTEIN data. Attachment: "Exploratory ASCA observation of broad absorption line quasi-stellar objects".

  17. COMOVING SPACE DENSITY AND OBSCURED FRACTION OF HIGH-REDSHIFT ACTIVE GALACTIC NUCLEI IN THE SUBARU/XMM-NEWTON DEEP SURVEY

    SciTech Connect

    Hiroi, Kazuo; Ueda, Yoshihiro; Akiyama, Masayuki; Watson, Mike G.

    2012-10-10

    We study the comoving space density of X-ray-selected luminous active galactic nuclei (AGNs) and the obscured AGN fraction at high redshifts (3 < z < 5) in the Subaru/XMM-Newton Deep Survey field. From an X-ray source catalog with high completeness of optical identification thanks to deep optical images, we select a sample of 30 AGNs at z > 3 with intrinsic (de-absorbed and rest-frame 2-10 keV) luminosities of L{sub X} = 10{sup 44-45} erg s{sup -1} detected in the 0.5-2 keV band, consisting of 20 and 10 objects with spectroscopic and photometric redshifts, respectively. Utilizing the 1/V{sub max} method, we confirm that the comoving space density of luminous AGNs decreases with redshift above z > 3. When combined with the Chandra-COSMOS result of Civano et al., the density decline of AGNs with L{sub X} = 10{sup 44-45} erg s{sup -1} is well represented by a power law of (1 + z){sup -6.2{+-}0.9}. We also determine the fraction of X-ray obscured AGNs with N{sub H} > 10{sup 22} cm{sup -2} in the Compton-thin population to be 0.54{sup +0.17}{sub -0.19}, by carefully taking into account observational biases including the effects of photon statistics for each source. This result is consistent with an independent determination of the type-2 AGN fraction based on optical properties, for which the fraction is found to be 0.59 {+-} 0.09. Comparing our result with that obtained in the local universe, we conclude that the obscured fraction of luminous AGNs increases significantly from z = 0 to z > 3 by a factor of 2.5 {+-} 1.1.

  18. Starburst or AGN dominance in submm-luminous candidate AGN

    NASA Astrophysics Data System (ADS)

    Coppin, Kristen; Alexander, Dave; Aretxaga, Itziar; Blain, Andrew; Chapman, Scott; Clements, Dave; Dunlop, James; Dunne, Loretta; Dye, Simon; Farrah, Duncan; Hughes, David; Ivison, Rob; Kim, Sungeun; Menendez-Delmestre, Karin; Oliver, Sebastian; Page, Mat; Pope, Alexandra; Rowan-Robinson, Michael; Scott, Douglas; Smail, Ian; Swinbank, Mark; Vaccari, Mattia; van Kampen, Eelco

    2008-03-01

    It is widely believed that starbursts/ULIRGs and AGN activity are triggered by galaxy interactions and merging; and sub-mm selected galaxies (SMGs) seem to be simply high redshift ULIRGs, observed near the peak of activity. In this evolutionary picture every SMG would host an AGN, which would eventually grow a black hole strong enough to blow off all of the gas and dust leaving an optically luminous QSO. In order to probe this evolutionary sequence, a crucial sub-sample to focus on would be the 'missing link' sources, which demonstrate both strong starburst and AGN signatures and to determine if the starburst is the main power source even in SMGs when we have evidence that an AGN is present. The best way to determine if a dominant AGN is present is to look in the mid-IR for their signatures, since often even deep X-ray observations miss identifying the presence of AGN in heavily dust-obscured SMGs. We have selected a sample of SMGs which are good candidates for harboring powerful AGN on the basis of their IRAC colours (S8um/S4.5um>2). Once we confirm these SMGs are AGN-dominated, we can then perform an audit of the energy balance between star-formation and AGN within this special sub-population of SMGs where the BH has grown appreciably to begin heating the dust emission. The proposed observations with IRS will probe the physics of how SMGs evolve from a cold-dust starburst-dominated ULIRG to an AGN/QSO by measuring the level of the mid-IR continuum, PAH luminosity, and Si absorption in these intermediate `transitory' AGN/SMGs.

  19. Right ventricular ejection fraction: an indicator of increased mortality in patients with congestive heart failure associated with coronary artery disease

    SciTech Connect

    Polak, J.F.; Holman, B.L.; Wynne, J.; Colucci, W.S.

    1983-08-01

    The predictive value of radionuclide ventriculography was studied in 34 patients with depressed left ventricular ejection fraction (less than 40%) and clinically evident congestive heart failure secondary to atherosclerotic coronary artery disease. In addition to left ventricular ejection fraction, right ventricular ejection fraction and extent of left ventricular paradox were obtained in an attempt to identify a subgroup at increased risk of mortality during the ensuing months. The 16 patients who were alive after a 2 year follow-up period had a higher right ventricular ejection fraction and less extensive left ventricular dyskinesia. When a right ventricular ejection fraction of less than 35% was used as a discriminant, mortality was significantly greater among the 21 patients with a depressed right ventricular ejection fraction (71 versus 23%), a finding confirmed by a life table analysis. It appears that the multiple factors contributing to the reduction in right ventricular ejection fraction make it a useful index not only for assessing biventricular function, but also for predicting patient outcome.

  20. Models of AGN feedback

    NASA Astrophysics Data System (ADS)

    Combes, Françcoise

    2015-02-01

    The physical processes responsible of sweeping up the surrounding gas in the host galaxy of an AGN, and able in some circumstances to expel it from the galaxy, are not yet well known. The various mechanisms are briefly reviewed: quasar or radio modes, either momentum-conserving outflows, energy-conserving outflows, or intermediate. They are confronted to observations, to know whether they can explain the M-sigma relation, quench the star formation or whether they can also provide some positive feedback and how the black hole accretion history is related to that of star formation.

  1. Increasing the filling fraction of ultracold polar KRb molecules in a 3D optical lattice

    NASA Astrophysics Data System (ADS)

    Moses, Steven; Gadway, Bryce; Yan, Bo; Covey, Jacob; Jin, Deborah; Ye, Jun

    2013-05-01

    Gases of ultracold polar molecules with sufficiently low entropy are an ideal experimental scenario to look for signatures of long-range many-body interactions. Having a high filling fraction in a 3D lattice is one way to achieve a low entropy state. In earlier work, we showed that preformed pairs of K and Rb in a 3D lattice (sites that have exactly one K and one Rb) are converted to KRb Feshbach molecules with nearly 100% efficiency. Since the STIRAP transfer from Feshbach molecules to ground-state molecules is 90-100% efficient, loading a 3D lattice with a large fraction of preformed pairs will lead to a large filling fraction of ground-state molecules. Our scheme is to load a Mott insulator of Rb and band insulator of K. After we have loaded a lattice with a high filling fraction, we will investigate effects of dipolar interactions in a many-body system. We acknowledge funding from NIST, NSF, AFOSR-MURI, and the NDSEG Graduate Fellowship.

  2. Obscured accretion from AGN surveys

    NASA Astrophysics Data System (ADS)

    Vignali, Cristian

    2014-07-01

    Recent models of super-massive black hole (SMBH) and host galaxy joint evolution predict the presence of a key phase where accretion, traced by obscured Active Galactic Nuclei (AGN) emission, is coupled with powerful star formation. Then feedback processes likely self-regulate the SMBH growth and quench the star-formation activity. AGN in this important evolutionary phase have been revealed in the last decade via surveys at different wavelengths. On the one hand, moderate-to-deep X-ray surveys have allowed a systematic search for heavily obscured AGN, up to very high redshifts (z~5). On the other hand, infrared/optical surveys have been invaluable in offering complementary methods to select obscured AGN also in cases where the nuclear X-ray emission below 10 keV is largely hidden to our view. In this review I will present my personal perspective of the field of obscured accretion from AGN surveys.

  3. The most luminous H α emitters at z ˜ 0.8-2.23 from HiZELS: evolution of AGN and star-forming galaxies

    NASA Astrophysics Data System (ADS)

    Sobral, David; Kohn, Saul A.; Best, Philip N.; Smail, Ian; Harrison, Chris M.; Stott, John; Calhau, João; Matthee, Jorryt

    2016-04-01

    We use new near-infrared spectroscopic observations to investigate the nature and evolution of the most luminous Hα emitters at z ˜ 0.8-2.23, which evolve strongly in number density over this period, and compare them to more typical Hα emitters. We study 59 luminous Hα emitters with LHα > L_{Hα }^{ast }, roughly equally split per redshift slice at z ˜ 0.8, 1.47 and 2.23 from the HiZELS and CF-HiZELS surveys. We find that, overall, 30 ± 8 per cent are active galactic nuclei [AGNs; 80 ± 30 per cent of these AGNs are broad-line AGNs, BL-AGNs], and we find little to no evolution in the AGN fraction with redshift, within the errors. However, the AGN fraction increases strongly with Hα luminosity and correlates best with LHα/L_{Hα }^{ast }(z). While LHα ≤ L_{Hα }^{ast }(z) Hα emitters are largely dominated by star-forming galaxies (>80 per cent), the most luminous Hα emitters (L_{Hα }>10L_{Hα }^{ast }(z)) at any cosmic time are essentially all BL-AGN. Using our AGN-decontaminated sample of luminous star-forming galaxies, and integrating down to a fixed Hα luminosity, we find a factor of ˜1300 evolution in the star formation rate density from z = 0 to 2.23. This is much stronger than the evolution from typical Hα star-forming galaxies and in line with the evolution seen for constant luminosity cuts used to select `ultraluminous' infrared galaxies and/or sub-millimetre galaxies. By taking into account the evolution in the typical Hα luminosity, we show that the most strongly star-forming Hα-selected galaxies at any epoch (L_{Hα }>L^{ast }_{Hα }(z)) contribute the same fractional amount of ≈15 per cent to the total star formation rate density, at least up to z = 2.23.

  4. The merging/AGN connection. II. Ionization of the circumnuclear regions

    NASA Astrophysics Data System (ADS)

    Sánchez, S. F.; Becker, T.; Garcia-Lorenzo, B.; Benn, C. R.; Christensen, L.; Kelz, A.; Jahnke, K.; Roth, M. M.

    2005-01-01

    We report the first results of a study of a sample of 20 galaxy mergers/interacting systems, using the VIMOS and PMAS integral field spectrographs. For each object, we extracted the integrated spectrum of the central regions and analyzed the ionization state using classical diagnostic diagrams \\citep{veil87}. There is evidence of AGN ionization in 4 of the objects, i.e. 20% of the sample, a considerably higher fraction than found in previous studies (˜4%). An increase of the nuclear activity with the far infrared temperature may account for the difference.

  5. Starburst or AGN Dominance in Submillimetre-Luminous Candidate AGN?

    NASA Astrophysics Data System (ADS)

    Coppin, Kristen; Pope, Alexandra; Menéndez-Delmestre, Karín; Alexander, David M.; Dunlop, James

    2010-06-01

    It is widely believed that ultraluminous infrared (IR) galaxies and active galactic nuclei (AGN) activity are triggered by galaxy interactions and merging, with the peak of activity occurring at z~2, where submillimetre galaxies are thousands of times more numerous than local ULIRGs. In this evolutionary picture, submillimetre galaxies (SMGs) would host an AGN, which would eventually grow a black hole (BH) strong enough to blow off all of the gas and dust leaving an optically luminous QSO. To probe this evolutionary sequence we have focussed on the `missing link' sources, which demonstrate both strong starburst (SB) and AGN signatures, in order to determine if the SB is the main power source even in SMGs when we have evidence that an AGN is present from their IRAC colours. The best way to determine if a dominant AGN is present is to look for their signatures in the mid-infrared with the Spitzer IRS, since often even deep X-ray observations miss identifying the presence of AGN in heavily dust-obscured SMGs. We present the results of our audit of the energy balance between star-formation and AGN within this special sub-population of SMGs-where the BH has grown appreciably to begin heating the dust emission.

  6. Molecular characterization of compost at increasing stages of maturity. 1. Chemical fractionation and infrared spectroscopy.

    PubMed

    Spaccini, Riccardo; Piccolo, Alessandro

    2007-03-21

    Composted organic biomasses at 60, 90, and 150 days of maturity were studied for changes in molecular composition. Compost samples were subjected to a mild sequential fractionation based on (1) organic solvent extraction, (2) transesterification with boron trifluoride in methanol (BF3-CH3OH), and (3) methanolic alkaline hydrolysis (KOH-CH3OH). The general chemical variations in compost residues following fractionation were monitored by DRIFT spectroscopy, whereas the molecular components separated along the fractionation steps were identified by GC-MS. DRIFT spectra suggested a progressive decrease of biolabile compounds such as alkyls, carbohydrates, and proteinaceous materials with compost maturity. Extraction of unbound components in an organic solvent indicated a considerable reduction of linear and branched alkanoic acids, both saturated and unsaturated, n-alkanes, and n-alkanols with enhancing compost maturity. Extracts of weakly bound molecules by transesterification revealed a decrease, with compost maturity, of components from more recalcitrant plant polyesters, such as omega-, di-, and trihydroxy acids, dioic acids, and n-alkanols. Extracts of strongly bound molecules by alkaline hydrolysis indicated a lower decrease of the same components, suggesting their reduced availability when in stable hydrophobic domains of progressively mature compost. The largest decrease in molecular components occurred when compost was stabilized from 60 to 90 days, whereas its composition did not significantly vary after stabilization at 150 days. The molecular structures of a number of steroids and terpenes appeared to be less susceptible to transformation with composting maturity, thereby resulting as useful biomarkers to trace the fate of composted organic matter in the environment. This work showed that a detailed molecular characterization of compost by a stepwise chemical fractionation enables the evaluation of compost maturity and origin of composted biomasses, as well

  7. New Insights on the Accretion Disk-Winds Connection in Radio-Loud AGNs from Suzaku

    NASA Technical Reports Server (NTRS)

    Tombesi, F.; Sambruna, R. M.; Reeves, J. N.; Braito, V.; Cappi, M.; Reynolds, S.; Mushotzky, R. F.

    2011-01-01

    From the spectral analysis of long Suzaku observations of five radio-loud AGNs we have been able to discover the presence of ultra-fast outflows with velocities ,,approx.0.1 c in three of them, namely 3C III, 3C 120 and 3C 390.3. They are consistent with being accretion disk winds/outflows. We also performed a follow-up on 3C III to monitor its outflow on approx.7 days time-scales and detected an anti-correlated variability of a possible relativistic emission line with respect to blue-shifted Fe K features, following a flux increase. This provides the first direct evidence for an accretion disc-wind connection in an AGN. The mass outflow rate of these outflows can be comparable to the accretion rate and their mechanical power can correspond to a significant fraction of the bolometric luminosity and is comparable to their typical jet power. Therefore, they can possibly play a significant role in the expected feedback from AGNs and can give us further clues on the relation between the accretion disk and the formation of winds/jets.

  8. PRIMUS: The Dependence of AGN Accretion on Host Stellar Mass and Color

    NASA Astrophysics Data System (ADS)

    Aird, James; Coil, Alison L.; Moustakas, John; Blanton, Michael R.; Burles, Scott M.; Cool, Richard J.; Eisenstein, Daniel J.; Smith, M. Stephen M.; Wong, Kenneth C.; Zhu, Guangtun

    2012-02-01

    We present evidence that the incidence of active galactic nuclei (AGNs) and the distribution of their accretion rates do not depend on the stellar masses of their host galaxies, contrary to previous studies. We use hard (2-10 keV) X-ray data from three extragalactic fields (XMM-LSS, COSMOS, and ELAIS-S1) with redshifts from the Prism Multi-object Survey to identify 242 AGNs with L 2-10 keV = 1042-44 erg s-1 within a parent sample of ~25,000 galaxies at 0.2 < z < 1.0 over ~3.4 deg2 and to i ~ 23. We find that although the fraction of galaxies hosting an AGN at fixed X-ray luminosity rises strongly with stellar mass, the distribution of X-ray luminosities is independent of mass. Furthermore, we show that the probability that a galaxy will host an AGN can be defined by a universal Eddington ratio distribution that is independent of the host galaxy stellar mass and has a power-law shape with slope -0.65. These results demonstrate that AGNs are prevalent at all stellar masses in the range 9.5 and that the same physical processes regulate AGN activity in all galaxies in this stellar mass range. While a higher AGN fraction may be observed in massive galaxies, this is a selection effect related to the underlying Eddington ratio distribution. We also find that the AGN fraction drops rapidly between z ~ 1 and the present day and is moderately enhanced (factor ~2) in galaxies with blue or green optical colors. Consequently, while AGN activity and star formation appear to be globally correlated, we do not find evidence that the presence of an AGN is related to the quenching of star formation or the color transformation of galaxies.

  9. Increased nitrogen deposition did not affect the composition and turnover of plant and microbial biomarkers in forest soil density fractions

    NASA Astrophysics Data System (ADS)

    Griepentrog, Marco; Bodé, Samuel; Boeckx, Pascal; Hagedorn, Frank; Wiesenberg, Guido L. B.; Schmidt, Michael W. I.

    2013-04-01

    Increased atmospheric nitrogen (N) deposition and elevated CO2 concentrations affect many forests and their ecosystem functions, including organic matter cycling in soils, the largest carbon pool of terrestrial ecosystems. However, it is still not clear how, and what the underlying mechanisms are. Specific molecules of plant and microbial origin (biomarkers) might respond differently to N deposition, depending on their internal N content. Microbial cell-wall-constituents with high-N content like amino sugars are reliable biomarkers to distinguish between fungal- and bacterial-derived organic residues. Individual lipids are plant-specific biomarkers that lack N in their molecular structure. Here, we tested the effects of elevated CO2 and increased N deposition on the dynamics of plant and microbial biomarkers by studying their composition and turnover in forest soil density fractions. Furthermore, we tested the hypothesis that these biomarkers respond differently to increased N deposition, depending on their internal N content. We used soil samples from a 4-year elevated CO2 and N deposition experiment in model forest ecosystems (open-top chambers), that were fumigated with ambient and 13C-depleted CO2 and treated with two levels of 15N-labeled fertilizer. Bulk soil was separated into free light fraction, occluded light fraction and heavy fraction by density fractionation and ultrasonic dispersion. The heavy fraction was further particle-size fractionated with 20 μm as a cut-off. We determined carbon and N concentrations and their isotopic compositions (δ13C, δ15N) within bulk soil and density fractions. Therein, we extracted and quantified individual amino sugars and lipids and conducted compound-specific stable-isotope-analysis using GC- and LC-IRMS. Results show that amino sugars were mainly stabilized in association with soil minerals. Especially bacterial amino sugars were preferentially associated with soil minerals, exemplified by a consistent decrease

  10. Long-term X-Ray Spectral Variability in AGN from the Palomar sample observed by Swift

    NASA Astrophysics Data System (ADS)

    Connolly, S. D.; McHardy, I. M.; Skipper, C. J.; Emmanoulopoulos, D.

    2016-04-01

    We present X-ray spectral variability of 24 local active galactic nuclei (AGN) from the Palomar sample of nearby galaxies, as observed mainly by Swift. From hardness ratio measurements, we find that 18 AGN with low accretion rates show hardening with increasing count rate, converse to the softer-when-brighter behaviour normally observed in AGN with higher accretion rates. Two AGN show softening with increasing count rate, two show more complex behaviour, and two do not show any simple relationship. Sufficient data were available for the spectra of 13 AGN to be summed in flux-bins. In 9 of these sources, correlated luminosity-dependent changes in the photon index (Γ) of a power-law component are found to be the main cause of hardness variability. For 6 objects, with a low accretion rate as a fraction of the Eddington rate (ṁEdd), Γ is anticorrelated with ṁEdd, i.e. `harder-when-brighter' behaviour is observed. The 3 higher-ṁEdd-rate objects show a positive correlation between Γ and ṁEdd. This transition from harder-when-brighter at low ṁEdd~to softer-when-brighter at high ṁEdd~can be explained by a change in the dominant source of seed-photons for X-ray emission from cyclo-synchrotron emission from the Comptonising corona itself to thermal seed-photons from the accretion disc. This transition is also seen in the `hard state' of black hole X-ray binaries (BHXRBs). The results support the idea that LINERs are analogues of BHXRBs in the hard state and that Seyferts are analogues of BHXRBs in either the high-accretion-rate end of the hard state or in the hard-intermediate state.

  11. Long-term X-ray spectral variability in AGN from the Palomar sample observed by Swift

    NASA Astrophysics Data System (ADS)

    Connolly, S. D.; McHardy, I. M.; Skipper, C. J.; Emmanoulopoulos, D.

    2016-07-01

    We present X-ray spectral variability of 24 local active galactic nuclei (AGN) from the Palomar sample of nearby galaxies, as observed mainly by Swift. From hardness ratio measurements, we find that 18 AGN with low accretion rates show hardening with increasing count rate, converse to the softer-when-brighter behaviour normally observed in AGN with higher accretion rates. Two AGN show softening with increasing count rate, two show more complex behaviour, and two do not show any simple relationship. Sufficient data were available for the spectra of 13 AGN to be summed in flux-bins. In nine of these sources, correlated luminosity-dependent changes in the photon index (Γ) of a power-law component are found to be the main cause of hardness variability. For six objects, with a low accretion rate as a fraction of the Eddington rate (dot{m}_{Edd}), Γ is anticorrelated with dot{m}_{Edd}, i.e. `harder-when-brighter' behaviour is observed. The three higher dot{m}_{Edd}-rate objects show a positive correlation between Γ and dot{m}_{Edd}. This transition from harder-when-brighter at low dot{m}_{Edd}to softer-when-brighter at high dot{m}_{Edd} can be explained by a change in the dominant source of seed-photons for X-ray emission from cyclo-synchrotron emission from the Comptonizing corona itself to thermal seed-photons from the accretion disc. This transition is also seen in the `hard state' of black hole X-ray binaries (BHXRBs). The results support the idea that low-ionization nuclear emission-line regions are analogues of BHXRBs in the hard state and that Seyferts are analogues of BHXRBs in either the high-accretion rate end of the hard state or in the hard-intermediate state.

  12. X-ray spectral properties of the AGN sample in the northern XMM-XXL field

    NASA Astrophysics Data System (ADS)

    Liu, Zhu; Merloni, Andrea; Georgakakis, Antonis; Menzel, Marie-Luise; Buchner, Johannes; Nandra, Kirpal; Salvato, Mara; Shen, Yue; Brusa, Marcella; Streblyanska, Alina

    2016-06-01

    In this paper we describe and publicly release a catalogue consisting of 8445 point-like X-ray sources detected in the XMM-XXL north survey. For the 2512 AGN which have reliable spectroscopy from SDSS-III/BOSS, we present the X-ray spectral fitting which has been computed with a Bayesian approach. We have also applied an X-ray spectral stacking method to different sub-samples, selected on the basis of the AGN physical properties (L2-10 keV, z, MBH, λEdd and NH). We confirm the well-known Iwasawa-Taniguchi effect in our luminosity-redshift sub-samples, and argue that such an effect is due to a decrease in the covering factor of a distant obscuring `torus' with increasing X-ray luminosity. By comparing the distribution of the reflection fraction, the ratio of the normalization of the reflected component to the direct radiation, we find that the low-luminosity, low-redshift sub-sample had systematically higher reflection fraction values than the high-redshift, high-luminosity one. On the other hand, no significant difference is found between samples having similar luminosity but different redshift, suggesting that the structure of the torus does not evolve strongly with redshift. Contrary to previous works, we do not find evidence for an increasing photon index at high Eddington ratio. This may be an indication that the structure of the accretion disc changes as the Eddington ratio approaches unity. Comparing our X-ray spectral analysis results with the optical spectral classification, we find that ˜20 per cent of optical type-1 AGN show an X-ray absorbing column density higher than 1021.5 cm- 2, and about 50 per cent of type-2 AGN have an X-ray absorbing column density less than 1021.5 cm- 2. We suggest that the excess X-ray absorption shown in the high-luminosity optical type-1 AGN can be due to small-scale dust-free gas within (or close to) the broad-line region, while in the low-luminosity ones it can be due to a clumpy torus with a large covering factor.

  13. A Herschel View on Galaxy/AGN Co-Evolution

    NASA Astrophysics Data System (ADS)

    Lutz, D.; Pep Consortium

    2011-10-01

    Deep far-infrared photometric surveys studying galaxy evolution and the nature of the cosmic infrared background are a key strength of the Herschel mission. The PACS Evolutionary Probe (PEP) guaranteed time key program obtains deep photometric surveys of some of the key extragalactic multiwavelength fields at wavelengths between 70 and 160μm. This contribution gives an overview of first science results, illustrating the potential of Herschel in providing calorimetric star formation rates for various high redshift galaxy populations, thus testing and superseding previous extrapolations from other wavelengths, and enabling a wide range of galaxy evolution studies. Herschel measured star formation rates of high redshift X-ray AGN suggest an interplay between two paths of AGN/host coevolution. A correlation of AGN luminosity and host star formation is traced locally over a wide range of luminosities and also extends to luminous high-z AGN. This correlation reflects an evolutionary connection, likely via merging. For lower AGN luminosities, star formation is similar to that in non-active massive galaxies and shows little dependence on AGN luminosity. The level of this secular, non-merger driven star formation increasingly dominates over the correlation at increasing redshift.

  14. MERGING AND CLUSTERING OF THE SWIFT BAT AGN SAMPLE

    SciTech Connect

    Koss, Michael; Mushotzky, Richard; Veilleux, Sylvain; Winter, Lisa

    2010-06-20

    We discuss the merger rate, close galaxy environment, and clustering on scales up to an Mpc of the Swift BAT hard X-ray sample of nearby (z<0.05), moderate-luminosity active galactic nuclei (AGNs). We find a higher incidence of galaxies with signs of disruption compared to a matched control sample (18% versus 1%) and of close pairs within 30 kpc (24% versus 1%). We also find a larger fraction with companions compared to normal galaxies and optical emission line selected AGNs at scales up to 250 kpc. We hypothesize that these merging AGNs may not be identified using optical emission line diagnostics because of optical extinction and dilution by star formation. In support of this hypothesis, in merging systems we find a higher hard X-ray to [O III] flux ratio, as well as emission line diagnostics characteristic of composite or star-forming galaxies, and a larger IRAS 60 {mu}m to stellar mass ratio.

  15. AGN proximity zone fossils and the delayed recombination of metal lines

    NASA Astrophysics Data System (ADS)

    Oppenheimer, Benjamin D.; Schaye, Joop

    2013-09-01

    We model the time-dependent evolution of metal-enriched intergalactic and circumgalactic gas exposed to the fluctuating radiation field from an active galactic nucleus (AGN). We consider diffuse gas densities (nH = 10-5-10-2.5 cm-3) exposed to the extra-galactic background (EGB) and initially in thermal equilibrium (T ˜ 104-104.5 K). Once the proximate AGN field turns on, additional photo-ionization rapidly ionizes the HI and metals. The enhanced AGN radiation field turns off after a typical AGN lifetime (τAGN = 1-20 Myr) and the field returns to the EGB intensity, but the metals remain out of ionization equilibrium for time scales that can significantly exceed τAGN. We define this phase as the AGN proximity zone `fossil' phase and show that high ionization stages (e.g. OVI, NeVIII, MgX) are in general enhanced, while the abundances of low ions (e.g. CIV, OIV, MgII) are reduced. In contrast, HI re-equilibrates rapidly (≪τAGN) owing to its low neutral fraction at diffuse densities. We demonstrate that metal column densities of intervening gas observed in absorption in quasar sight lines are significantly affected by delayed recombination for a wide range of densities, metallicities, AGN strengths, AGN lifetimes and AGN duty cycles. As an example, we show that a fossil zone model can simultaneously reproduce the observed NeVIII, MgII, HI and other metal columns of the z = 0.927 PG1206+259 absorption system observed by Tripp et al. using a single, T ˜ 104 K phase model. At low redshift even moderate-strength AGN that are off for 90 per cent of the time could significantly enhance the high-ion metal columns in the circum-galactic media of galaxies observed without active AGN. Fossil proximity zones may be particularly important during the quasar era, z ˜ 2-5. Indeed, we demonstrate that at these redshifts a large fraction of the metal-enriched intergalactic medium may consist of out-of-equilibrium fossil zones. AGN proximity zone fossils allow a whole new class

  16. The complete census of optically selected AGNs in the Coma supercluster: the dependence of AGN activity on the local environment

    NASA Astrophysics Data System (ADS)

    Gavazzi, G.; Savorgnan, G.; Fumagalli, Mattia

    2011-10-01

    Aims: To investigate the dependence of the occurrence of active galactic nuclei (AGNs) on local galaxy density, we study the nuclear properties of ~5000 galaxies in the Coma supercluster whose density spans two orders of magnitude from the sparse filaments to the cores of rich clusters. Methods: We obtained optical spectra of the nuclei of 283 galaxies using the 1.5 m Cassini telescope of Bologna observatory. Among these galaxies, 177 belong to the Coma supercluster and are added to the 4785 spectra available from SDSS (DR7) to fill-in the incomplete coverage by SDSS of luminous galaxies. We perform a spectral classification of the nuclei of galaxies in this region (with a completeness of 98% at r ≤ 17.77), classifying the nuclear spectra in six classes: three of them (SEY, sAGN, LIN) refer to AGNs and the remaining three (HII, RET, PAS) refer to different stages of starburst activity. We perform this classification as recommended by Cid Fernandes and collaborators using the ratio of λ 6584 [NII] to Hα lines and the equivalent width of Hα (WHAN diagnostic), after correcting the last quantity by 1.3 Å for underlying absorption. Results: We find that 482 (10%) of 5027 galaxies host an AGN: their frequency strongly increases with increasing luminosity of the parent galaxies, such that 32% of galaxies with Log(Li/L⊙) ≥ 10.2 harbor an AGN at their interior. In addition to their presence in luminous galaxies, AGNs are also found in red galaxies with ⟨g - i⟩ ≃ 1.15 ± 0.15 mag. The majority of SEY and sAGN (strong AGNs) are associated with luminous late-type (or S0a) galaxies, while LIN (weak AGNs) and RET ("retired": nuclei that have experienced a starburst phase in the past and are now ionized by their hot evolved low-mass stars), are mostly found among E/S0as. The number density of AGNs, HII region-like, and retired galaxies is found to anti-correlate with the local density of galaxies, such that their frequency drops by a factor of two near the cluster

  17. AGN Science: The Past, The Present, The Future . AGN Science

    NASA Astrophysics Data System (ADS)

    Boller, Th.

    I review some basic results on AGN science by concentrating on the Fe K and Fe L line observations and on the Narrow-Line Seyfert 1 physics. This paper is based on a talk given at the Vulcano workshop, 'The multifrequency behavior of high energy cosmic sources` in 2009. Given the length of the talk and the number of pages the review on AGN science cannot be complete and is biased towards two science topics and my personal view.

  18. An Increasing Stellar Baryon Fraction in Bright Galaxies at High Redshift

    NASA Astrophysics Data System (ADS)

    Finkelstein, Steven L.; Song, Mimi; Behroozi, Peter; Somerville, Rachel S.; Papovich, Casey; Milosavljević, Miloš; Dekel, Avishai; Narayanan, Desika; Ashby, Matthew L. N.; Cooray, Asantha; Fazio, Giovanni G.; Ferguson, Henry C.; Koekemoer, Anton M.; Salmon, Brett; Willner, S. P.

    2015-12-01

    Recent observations have shown that the characteristic luminosity of the rest-frame ultraviolet (UV) luminosity function does not significantly evolve at 4 < z < 7 and is approximately {M}{UV}*˜ -21. We investigate this apparent non-evolution by examining a sample of 173 bright, MUV < -21 galaxies at z = 4-7, analyzing their stellar populations and host halo masses. Including deep Spitzer/IRAC imaging to constrain the rest-frame optical light, we find that {M}{UV}* galaxies at z = 4-7 have similar stellar masses of log(M/M⊙) = 9.6-9.9 and are thus relatively massive for these high redshifts. However, bright galaxies at z = 4-7 are less massive and have younger inferred ages than similarly bright galaxies at z = 2-3, even though the two populations have similar star formation rates and levels of dust attenuation for a fixed dust-attenuation curve. Matching the abundances of these bright z = 4-7 galaxies to halo mass functions from the Bolshoi ΛCDM simulation implies that the typical halo masses in ˜ {M}{{UV}}* galaxies decrease from log(Mh/M⊙) = 11.9 at z = 4 to log(Mh/M⊙) = 11.4 at z = 7. Thus, although we are studying galaxies at a similar stellar mass across multiple redshifts, these galaxies live in lower mass halos at higher redshift. The stellar baryon fraction in ˜ {M}{{UV}}* galaxies in units of the cosmic mean Ωb/Ωm rises from 5.1% at z = 4 to 11.7% at z = 7; this evolution is significant at the ˜3σ level. This rise does not agree with simple expectations of how galaxies grow, and implies that some effect, perhaps a diminishing efficiency of feedback, is allowing a higher fraction of available baryons to be converted into stars at high redshifts.

  19. AGN and their host galaxies

    NASA Astrophysics Data System (ADS)

    Steinborn, L. K.; Dolag, K.; Hirschmann, M.; Remus, R.-S.; Teklu, A. F.

    2016-06-01

    Large scale cosmological hydrodynamic simulations are an important tool to study the co-evolution between black holes (BHs) and their host galaxies. However, in order to model the accretion onto BHs and AGN feedback we need sub-grid models which contain several free parameters. The choice of these parameters has a significant impact on the properties of the BHs and their host galaxies. Therefore, we improve the accretion model and the AGN feedback model based on both theory and observations to eliminate most free parameters. In that way, the slope of the observed relation between BH mass and stellar mass is reproduced self-consistently. We performed a few extremely large simulation runs as part of the Magneticum Pathfinder simulation set, combining a high resolution with very large cosmological volumes, enabling us to study for example dual AGN, the role of galaxy mergers and AGN clustering properties.

  20. Accretion Timescales from Kepler AGN

    NASA Astrophysics Data System (ADS)

    Kasliwal, Vishal P.; Vogeley, Michael S.; Richards, Gordon T.

    2015-01-01

    We constrain AGN accretion disk variability mechanisms using the optical light curves of AGN observed by Kepler. AGN optical fluxes are known to exhibit stochastic variations on timescales of hours, days, months and years. The excellent sampling properties of the original Kepler mission - high S/N ratio (105), short sampling interval (30 minutes), and long sampling duration (~ 3.5 years) - allow for a detailed examination of the differences between the variability processes present in various sub-types of AGN such as Type I and II Seyferts, QSOs, and Blazars. We model the flux data using the Auto-Regressive Moving Average (ARMA) representation from the field of time series analysis. We use the Kalman filter to determine optimal mode parameters and use the Akaike Information Criteria (AIC) to select the optimal model. We find that optical light curves from Kepler AGN cannot be fit by low order statistical models such as the popular AR(1) process or damped random walk. Kepler light curves exhibit complicated power spectra and are better modeled by higher order ARMA processes. We find that Kepler AGN typically exhibit power spectra that change from a bending power law (PSD ~ 1/fa) to a flat power spectrum on timescales in the range of ~ 5 - 100 days consistent with the orbital and thermal timescales of a typical 107 solar mass black hole.

  1. Fractional laser microablation of skin: increasing the efficiency of transcutaneous delivery of particles

    NASA Astrophysics Data System (ADS)

    Genina, E. A.; Dolotov, L. E.; Bashkatov, A. N.; Tuchin, V. V.

    2016-06-01

    We study several regimes of fractional laser microablation using a pulsed Er : YAG laser for producing microchannels of different depth and incisions that allow transcutaneous delivery of particles of different size, namely, Al2O3 (27 μm), ZrO2 (smaller than 5 μm) and TiO2 (smaller than 100 nm). The shock wave regime was used both for enhancing the penetration of particles into the ablation zones and as an independent method of particle delivery into the skin. Based on optical coherence tomography we assessed the coherent depth of particle detection in the skin in 2 hours, 3 days and 10 days after the administration. The maximal localisation depth (up to 450 μm) was obtained for TiO2 nanoparticles in the regime of incisions with enhancement of particle penetration by pulses of a multiple-beam hydrodynamic shock wave. The results of the study can be useful for developing new methods of transcutaneous delivery of micro- and nanocarriers of medicinal preparations.

  2. Jets in AGN at extremely high redshifts

    NASA Astrophysics Data System (ADS)

    Gurvits, Leonid I.; Frey, Sándor; Paragi, Zsolt

    2015-03-01

    The jet phenomenon is a trademark of active galactic nuclei (AGN). In most general terms, the current understanding of this phenomenon explains the jet appearance by effects of relativistic plasma physics. The fundamental source of energy that feeds the plasma flow is believed to be the gravitational field of a central supermassive black hole. While the mechanism of energy transfer and a multitude of effects controlling the plasma flow are yet to be understood, major properties of jets are strikingly similar in a broad range of scales from stellar to galactic. They are supposed to be controlled by a limited number of physical parameters, such as the mass of a central black hole and its spin, magnetic field induction and accretion rate. In a very simplified sense, these parameters define the formation of a typical core-jet structure observed at radio wavelengths in the region of the innermost central tens of parsecs in AGN. These core-jet structures are studied in the radio domain by Very Long Baseline Interferometry (VLBI) with milli- and sub-milliarcsecond angular resolution. Such structures are detectable at a broad range of redshifts. If observed at a fixed wavelength, a typical core-jet AGN morphology would appear as having a steep-spectrum jet fading away with the increasing redshift while a flat-spectrum core becoming more dominant. If core-jet AGN constitute the same population of objects throughout the redshift space, the apparent ``prominence'' of jets at higher redshifts must decrease (Gurvits 1999): well pronounced jets at high z must appear less frequent than at low z.

  3. AGN Observations with STACEE

    NASA Astrophysics Data System (ADS)

    Bramel, D. A.; Boone, L. M.; Carson, J.; Chae, E.; Covault, C. E.; Fortin, P.; Gingrich, D. M.; Hanna, D. S.; Hinton, J. A.; Mukherjee, R.; Mueller, C.; Ong, R. A.; Ragan, K.; Scalzo, R. A.; Schuette, D. R.; Theoret, C. G.; Williams, D. A.; Wong, J.; Zweerink, J.

    2003-03-01

    The Solar Tower Atmospheric Cherenkov Effect Experiment (STACEE) is a gamma-ray detector designed to study astrophysical sources at energies between 50 and 500 GeV. It uses 64 large, steerable mirrors at the National Solar Tower Test Facility near Albuquerque, NM, USA to collect Cherenkov light from extended air showers and concentrate it onto an array of photomultiplier tubes. The large light-collection area gives it a lower energy threshold than imaging-type Cherenkov detectors. STACEE is now fully operational, and we report here on the performance of the complete STACEE instrument, as well as preliminary results of recent observations of several AGN targets. This work was supported in part by the National Science Foundation (under Grant Numbers PHY-9983836, PHY-0070927, and PHY-0070953), the Natural Sciences and Engineering Research Council, Le Fond Quebecois de la Recherche sur la Nature et les Technologies (FQRNT), the Research Corporation, and the California Space Institute. CEC is a Cottrell Scholar of the Research Corporation.

  4. Eddington Ratio Distribution of X-Ray-selected Broad-line AGNs at 1.0 < z < 2.2

    NASA Astrophysics Data System (ADS)

    Suh, Hyewon; Hasinger, Günther; Steinhardt, Charles; Silverman, John D.; Schramm, Malte

    2015-12-01

    We investigate the Eddington ratio distribution of X-ray-selected broad-line active galactic nuclei (AGNs) in the redshift range 1.0 < z < 2.2, where the number density of AGNs peaks. Combining the optical and Subaru/Fiber Multi Object Spectrograph near-infrared spectroscopy, we estimate black hole masses for broad-line AGNs in the Chandra Deep Field South (CDF-S), Extended Chandra Deep Field South (E-CDF-S), and the XMM-Newton Lockman Hole (XMM-LH) surveys. AGNs with similar black hole masses show a broad range of AGN bolometric luminosities, which are calculated from X-ray luminosities, indicating that the accretion rate of black holes is widely distributed. We find a substantial fraction of massive black holes accreting significantly below the Eddington limit at z ≲ 2, in contrast to what is generally found for luminous AGNs at high redshift. Our analysis of observational selection biases indicates that the “AGN cosmic downsizing” phenomenon can be simply explained by the strong evolution of the comoving number density at the bright end of the AGN luminosity function, together with the corresponding selection effects. However, one might need to consider a correlation between the AGN luminosity and the accretion rate of black holes, in which luminous AGNs have higher Eddington ratios than low-luminosity AGNs, in order to understand the relatively small fraction of low-luminosity AGNs with high accretion rates in this epoch. Therefore, the observed downsizing trend could be interpreted as massive black holes with low accretion rates, which are relatively fainter than less-massive black holes with efficient accretion. Based in part on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

  5. STUDYING FAINT ULTRA-HARD X-RAY EMISSION FROM AGN IN GOALS LIRGS WITH SWIFT/BAT

    SciTech Connect

    Koss, Michael; Casey, Caitlin M.; Mushotzky, Richard; Veilleux, Sylvain; Baumgartner, Wayne; Tueller, Jack; Markwardt, Craig

    2013-03-10

    We present the first analysis of the all-sky Swift Burst Alert Telescope (BAT) ultra-hard X-ray (14-195 keV) data for a targeted list of objects. We find that the BAT data can be studied at three-times-fainter limits than in previous blind detection catalogs based on prior knowledge of source positions and using smaller energy ranges for source detection. We determine the active galactic nucleus (AGN) fraction in 134 nearby (z < 0.05) luminous infrared galaxies (LIRGs) from the GOALS sample. We find that LIRGs have a higher detection frequency than galaxies matched in stellar mass and redshift at 14-195 keV and 24-35 keV. In agreement with work at other wavelengths, the AGN detection fraction increases strongly at high IR luminosity with half of the high-luminosity LIRGs (50%, 6/12, log L{sub IR}/L{sub Sun} > 11.8) detected. The BAT AGN classification shows 97% (37/38) agreement with Chandra and XMM-Newton AGN classification using hardness ratios or detection of an iron K{alpha} line. This confirms our statistical analysis and supports the use of the Swift/BAT all-sky survey to study fainter populations of any category of sources in the ultra-hard X-ray band. BAT AGNs in LIRGs tend to show higher column densities with 40% {+-} 9% showing 14-195 keV/2-10 keV hardness flux ratios suggestive of high or Compton-thick column densities (log N{sub H} > 24 cm{sup -2}), compared to only 12% {+-} 5% of non-LIRG BAT AGNs. We also find that using specific energy ranges of the BAT detector can yield additional sources over total band detections with 24% (5/21) of detections in LIRGs at 24-35 keV not detected at 14-195 keV.

  6. Seminal plasma arising from the whole boar sperm-rich fraction increases the stability of sperm membrane after thawing.

    PubMed

    Torres, M A; Ravagnani, G M; Leal, D F; Martins, S M M K; Muro, B B D; Meirelles, F V; Papa, F O; Dell'aqua, J A; Alvarenga, M A; Moretti, A S; De Andrade, A F C

    2016-05-01

    Boar spermatozoa arising from the sperm-rich ejaculate fraction are reported to have a more stable plasma membrane and are more resistant to cold shock and premature acrosome reaction than spermatozoa from the whole ejaculate. Furthermore, seminal plasma (SP) can increase the cryotolerance of boar spermatozoa, and in other domestic species, it has the ability to reverse cryopreservation damage. This study aimed to evaluate the effects of boar SP arising from the whole sperm-rich ejaculate fraction (SP-SRF) on the integrity, stability, and peroxidation of sperm membranes after thawing. Each ejaculate ( = 24) was divided among 4 treatments: control (CT), centrifuged and suspended in autologous SP-SRF (CS), centrifuged with withdrawn SP-SRF (CW), and post-thawed SP arising from the whole sperm-rich fraction addition to CW (CWSP). After thawing, all treatments were incubated for 5, 60, and 120 min and were analyzed for membrane integrity, fluidity, and peroxidation by flow cytometer. The absence of SP-SRF increased the lipid disorder ( < 0.05) but had no effect on lipid peroxidation ( > 0.05) or membrane integrity ( > 0.05). However, the increase in lipid disorder by withdrawal of SP-SRF was reversed by SP-SRF addition ( < 0.05) to the post-thawing medium, whereas plasma and acrosomal membrane integrity ( > 0.05) and lipid peroxidation ( > 0.05) were unchanged. In conclusion, despite the centrifugation effects, the addition of SP arising from the whole sperm-rich fraction to post-thawed boar semen decreased sperm lipid disorder without an influence of the sperm membrane integrity and peroxidation. PMID:27285688

  7. Increasing the accuracy and automation of fractional vegetation cover estimation from digital photographs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of automated methods to estimate canopy cover (CC) from digital photographs has increased in recent years given its potential to produce accurate, fast and inexpensive CC measurements. Wide acceptance has been delayed because of the limitations of these methods. This work introduces a novel ...

  8. THE 60 MONTH ALL-SKY BURST ALERT TELESCOPE SURVEY OF ACTIVE GALACTIC NUCLEUS AND THE ANISOTROPY OF NEARBY AGNs

    SciTech Connect

    Ajello, M.; Madejski, G. M.; Alexander, D. M.; Greiner, J.; Burlon, D.; Gehrels, N.

    2012-04-10

    Surveys above 10 keV represent one of the best resources to provide an unbiased census of the population of active galactic nuclei (AGNs). We present the results of 60 months of observation of the hard X-ray sky with Swift/Burst Alert Telescope (BAT). In this time frame, BAT-detected (in the 15-55 keV band) 720 sources in an all-sky survey of which 428 are associated with AGNs, most of which are nearby. Our sample has negligible incompleteness and statistics a factor of {approx}2 larger over similarly complete sets of AGNs. Our sample contains (at least) 15 bona fide Compton-thick AGNs and 3 likely candidates. Compton-thick AGNs represent {approx}5% of AGN samples detected above 15 keV. We use the BAT data set to refine the determination of the log N-log S of AGNs which is extremely important, now that NuSTAR prepares for launch, toward assessing the AGN contribution to the cosmic X-ray background. We show that the log N-log S of AGNs selected above 10 keV is now established to {approx}10% precision. We derive the luminosity function of Compton-thick AGNs and measure a space density of 7.9{sup +4.1}{sub -2.9} Multiplication-Sign 10{sup -5} Mpc{sup -3} for objects with a de-absorbed luminosity larger than 2 Multiplication-Sign 10{sup 42} erg s{sup -1}. As the BAT AGNs are all mostly local, they allow us to investigate the spatial distribution of AGNs in the nearby universe regardless of absorption. We find concentrations of AGNs that coincide spatially with the largest congregations of matter in the local ({<=}85 Mpc) universe. There is some evidence that the fraction of Seyfert 2 objects is larger than average in the direction of these dense regions.

  9. The 60 Month All-Sky Burst Alert Telescope Survey of Active Galactic Nucleus and the Anisotropy of Nearby AGNs

    NASA Technical Reports Server (NTRS)

    Ajello, M.; Alexander, D. M.; Greiner, J.; Madejeski, G. M.; Gehrels, N.; Burlon, D.

    2014-01-01

    Surveys above 10 keV represent one of the best resources to provide an unbiased census of the population of active galactic nuclei (AGNs). We present the results of 60 months of observation of the hard X-ray sky with Swift/Burst Alert Telescope (BAT). In this time frame, BAT-detected (in the 15-55 keV band) 720 sources in an all-sky survey of which 428 are associated with AGNs, most of which are nearby. Our sample has negligible incompleteness and statistics a factor of approx. 2 larger over similarly complete sets of AGNs. Our sample contains (at least) 15 bona fide Compton-thick AGNs and 3 likely candidates. Compton-thick AGNs represent approx. 5% of AGN samples detected above 15 keV. We use the BAT data set to refine the determination of the log N-log S of AGNs which is extremely important, now that NuSTAR prepares for launch, toward assessing the AGN contribution to the cosmic X-ray background. We show that the log N-log S of AGNs selected above 10 keV is now established to approx. 10% precision. We derive the luminosity function of Compton-thick AGNs and measure a space density of 7.9(+4.1/-2.9)× 10(exp -5)/cubic Mpc for objects with a de-absorbed luminosity larger than 2 × 10(exp 42) erg / s. As the BAT AGNs are all mostly local, they allow us to investigate the spatial distribution of AGNs in the nearby universe regardless of absorption. We find concentrations of AGNs that coincide spatially with the largest congregations of matter in the local (much < 85 Mpc) universe. There is some evidence that the fraction of Seyfert 2 objects is larger than average in the direction of these dense regions..

  10. X-Ray Absorption, Nuclear Infrared Emission, and Dust Covering Factors of AGNs: Testing Unification Schemes

    NASA Astrophysics Data System (ADS)

    Mateos, S.; Carrera, F. J.; Alonso-Herrero, A.; Hernán-Caballero, A.; Barcons, X.; Asensio Ramos, A.; Watson, M. G.; Blain, A.; Caccianiga, A.; Ballo, L.; Braito, V.; Ramos Almeida, C.

    2016-03-01

    We present the distributions of the geometrical covering factors of the dusty tori (f2) of active galactic nuclei (AGNs) using an X-ray selected complete sample of 227 AGNs drawn from the Bright Ultra-hard XMM-Newton Survey. The AGNs have z from 0.05 to 1.7, 2-10 keV luminosities between 1042 and 1046 erg s-1, and Compton-thin X-ray absorption. Employing data from UKIDSS, 2MASS, and the Wide-field Infrared Survey Explorer in a previous work, we determined the rest-frame 1-20 μm continuum emission from the torus, which we model here with the clumpy torus models of Nenkova et al. Optically classified type 1 and type 2 AGNs are intrinsically different, with type 2 AGNs having, on average, tori with higher f2 than type 1 AGNs. Nevertheless, ˜20% of type 1 AGNs have tori with large covering factors, while ˜23%-28% of type 2 AGNs have tori with small covering factors. Low f2 are preferred at high AGN luminosities, as postulated by simple receding torus models, although for type 2 AGNs the effect is certainly small. f2 increases with the X-ray column density, which implies that dust extinction and X-ray absorption take place in material that share an overall geometry and most likely belong to the same structure, the putative torus. Based on our results, the viewing angle, AGN luminosity, and also f2 determine the optical appearance of an AGN and control the shape of the rest-frame ˜1-20 μm nuclear continuum emission. Thus, the torus geometrical covering factor is a key ingredient of unification schemes.

  11. Cooling, AGN Feedback and Star Formation in Cool-Core Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Li, Yuan; Bryan, Greg; Ruszkowski, Mateusz

    2015-01-01

    The feedback from active galactic nuclei (AGNs) is widely considered to be the major heating source in cool-core galaxy clusters to prevent a classical cooling flow. Numerical simulations with AGN feedback have successfully suppressed radiative cooling, but generally fail to reproduce the right amount of cold gas and the expected cyclical AGN activities. We perform adaptive mesh simulations including both momentum-driven AGN feedback and star formation to study the interplay between cooling, AGN heating and star formation over ~ 6.5 Gyr time in an isolated cool-core cluster. Cold clumps first cool out of the ICM due to the non-liner perturbation driven by the AGN jets. These cold clumps feed both star formation and the supermassive black hole (SMBH), triggering an AGN outburst which increases the entropy of the ICM and reduces its cooling rate. Within 1-2 Gyr, star formation completely consumes the cold gas, which leads to a brief shutoff of the AGN. The ICM quickly cools and develops multiphase gas again, followed by another cycle of star formation/AGN outburst. Within 6.5 Gyr, we observe three such cycles. The average star formation rate is ~40 solar mass/yr. The black hole accretion rate shows a large scatter, but the average correlates well with the star formation rate and is roughly one order of magnitude lower.

  12. AGN host galaxy mass function in COSMOS. Is AGN feedback responsible for the mass-quenching of galaxies?

    NASA Astrophysics Data System (ADS)

    Bongiorno, A.; Schulze, A.; Merloni, A.; Zamorani, G.; Ilbert, O.; La Franca, F.; Peng, Y.; Piconcelli, E.; Mainieri, V.; Silverman, J. D.; Brusa, M.; Fiore, F.; Salvato, M.; Scoville, N.

    2016-04-01

    We investigate the role of supermassive black holes in the global context of galaxy evolution by measuring the host galaxy stellar mass function (HGMF) and the specific accretion rate, that is, λSAR, the distribution function (SARDF), up to z ~ 2.5 with ~1000 X-ray selected AGN from XMM-COSMOS. Using a maximum likelihood approach, we jointly fit the stellar mass function and specific accretion rate distribution function, with the X-ray luminosity function as an additional constraint. Our best-fit model characterizes the SARDF as a double power-law with mass-dependent but redshift-independent break, whose low λSAR slope flattens with increasing redshift while the normalization increases. This implies that for a given stellar mass, higher λSAR objects have a peak in their space density at earlier epoch than the lower λSAR objects, following and mimicking the well-known AGN cosmic downsizing as observed in the AGN luminosity function. The mass function of active galaxies is described by a Schechter function with an almost constant M∗⋆ and a low-mass slope α that flattens with redshift. Compared to the stellar mass function, we find that the HGMF has a similar shape and that up to log (M⋆/M⊙) ~ 11.5, the ratio of AGN host galaxies to star-forming galaxies is basically constant (~10%). Finally, the comparison of the AGN HGMF for different luminosity and specific accretion rate subclasses with a previously published phenomenological model prediction for the "transient" population, which are galaxies in the process of being mass-quenched, reveals that low-luminosity AGN do not appear to be able to contribute significantly to the quenching and that at least at high masses, that is, M⋆ > 1010.7 M⊙, feedback from luminous AGN (log Lbol ≳ 46 [erg/s]) may be responsible for the quenching of star formation in the host galaxy.

  13. The AGN origin of cluster magnetic fields

    NASA Astrophysics Data System (ADS)

    Xu, Hao

    The origin of magnetic fields in galaxy clusters is one of the most fascinating but challenging problems in astrophysics. In this dissertation, the possibility of an Active Galactic Nucleus (AGN) origin of cluster magnetic fields is studied through state of the art simulations of magnetic field evolution in large scale structure formation using a newly developed cosmological Adaptive Mesh Refinement (AMR) Magnetohydrodynamics (MHD) code -- EnzoMHD. After presenting a complete but concise description and verification of the code, we discuss the creation of magnetic fields through the Biermann Battery effect during first star formation and galaxy cluster formation. We find that magnetic fields are produced as predicted by theory in both cases. For the first star formation, we obtain a lower limit of (~ 10 -9 G) for magnetic fields when the first generation stars form. On the other hand, we find that the magnetic energy is amplified 4 orders of magnitude within ~ 10 Gyr during cluster formation. We then study magnetic field injection from AGN into the Intra- Cluster Medium (ICM) and their impact on the ICM. We reproduce the X-ray cavities as well as weak shocks seen in observations in the simulation, and further confirm the idea that AGN outburst must contain lots of magnetic energy (up to 10 61 ergs) and the magnetic fields play an important part in the formation of jet/lobe system. We present high resolution simulations of cluster formation with magnetic fields injected from high redshift AGN. We find that these local magnetic fields are spread quickly throughout the whole cluster by cluster mergers. The ICM is in a turbulent state with a Kolmogorov-like power spectrum. Magnetic fields are amplified to and maintained at the observational level of a few mG by bulk flows at large scale and the ICM turbulence at small scale. The total magnetic energy increases about 25 times to ~ 1.2 × 10^61 ergs at the present time. We conclude that magnetic fields from AGN at high

  14. The impact of AGN on their host galaxies

    NASA Astrophysics Data System (ADS)

    Harrison, C. M.

    2014-07-01

    In these proceedings I briefly: (1) review the impact (or ``feedback'') that active galactic nuclei (AGN) are predicted to have on their host galaxies and larger scale environment, (2) review the observational evidence for or against these predictions and (3) present new results on ionised outflows in AGN. The observational support for the ``maintenance mode'' of feedback is strong (caveat the details); AGN at the centre of massive halos appear to be regulating the cooling of hot gas, which could in turn control the levels of future star formation (SF) and black hole growth. In contrast, direct observational support for more rapid forms of feedback, which dramatically impact on SF (i.e., the ``quasar mode''), remains elusive. From a systematic study of the spectra of ~24 000 AGN we find that extreme ionised gas kinematics are common, and are most prevalent in radio bright AGN (L 1.4 GHz > 103 W Hz-1). Follow-up IFU observations have shown that these extreme gas kinematics are extended over kilo-parsec scales. However, the co-existence of high-levels of SF, luminous AGN activity and radio jets raises interesting questions on the primary drivers and impact of these outflows. Galaxy-wide, high-mass outflows are being observed in an increasing number of AGN and are a plausible mechanism for the depletion of gas; however, there is still much work to be done to determine the physical processes that drive these outflows and to measure the level of impact that they have on their host galaxies.

  15. Light Fractionation Significantly Increases the Efficacy of Photodynamic Therapy Using BF-200 ALA in Normal Mouse Skin

    PubMed Central

    de Bruijn, Henriëtte S.; Brooks, Sander; van der Ploeg-van den Heuvel, Angélique; ten Hagen, Timo L. M.; de Haas, Ellen R. M.; Robinson, Dominic J.

    2016-01-01

    Background Light fractionation significantly increases the efficacy of 5-aminolevulinic acid (ALA) based photodynamic therapy (PDT) using the nano-emulsion based gel formulation BF-200. PDT using BF-200 ALA has recently been clinically approved and is under investigation in several phase III trials for the treatment of actinic keratosis. This study is the first to compare BF-200 ALA with ALA in preclinical models. Results In hairless mouse skin there is no difference in the temporal and spatial distribution of protoporphyrin IX determined by superficial imaging and fluorescence microscopy in frozen sections. In the skin-fold chamber model, BF-200 ALA leads to more PpIX fluorescence at depth in the skin compared to ALA suggesting an enhanced penetration of BF-200 ALA. Light fractionated PDT after BF-200 ALA application results in significantly more visual skin damage following PDT compared to a single illumination. Both ALA formulations show the same visual skin damage, rate of photobleaching and change in vascular volume immediately after PDT. Fluorescence immunohistochemical imaging shows loss of VE-cadherin in the vasculature at day 1 post PDT which is greater after BF-200 ALA compared to ALA and more profound after light fractionation compared to a single illumination. Discussion The present study illustrates the clinical potential of light fractionated PDT using BF-200 ALA for enhancing PDT efficacy in (pre-) malignant skin conditions such as basal cell carcinoma and vulval intraepithelial neoplasia and its application in other lesion such as cervical intraepithelial neoplasia and oral squamous cell carcinoma where current approaches have limited efficacy. PMID:26872051

  16. Compton thick AGN in the XMM-COSMOS survey

    NASA Astrophysics Data System (ADS)

    Lanzuisi, G.; Ranalli, P.; Georgantopoulos, I.; Georgakakis, A.; Delvecchio, I.; Akylas, T.; Berta, S.; Bongiorno, A.; Brusa, M.; Cappelluti, N.; Civano, F.; Comastri, A.; Gilli, R.; Gruppioni, C.; Hasinger, G.; Iwasawa, K.; Koekemoer, A.; Lusso, E.; Marchesi, S.; Mainieri, V.; Merloni, A.; Mignoli, M.; Piconcelli, E.; Pozzi, F.; Rosario, D. J.; Salvato, M.; Silverman, J.; Trakhtenbrot, B.; Vignali, C.; Zamorani, G.

    2015-01-01

    the optical spectra and SED agree with the classification as highly obscured sources: all the available optical spectra are dominated by the stellar component of the host galaxy, and to reproduce the broadband SED, a highly obscured torus component is needed for all the CT sources.Exploiting the high resolution Hubble-ACS images available, we are able to show that these highly obscured sources have a significantly larger merger fraction with respect to other X-ray selected samples of AGN. Finally we discuss the implications of our findings in the context of AGN/galaxy co-evolutionary models, and compare our results with the predictions of X-ray background synthesis models. Appendices are available in electronic form at http://www.aanda.org

  17. The Triggering and Evolution of AGN in Cluster Fields

    NASA Astrophysics Data System (ADS)

    Allen, Steven

    It is now well established that the evolution of super-massive black holes (SMBHs) is closely linked to that of their host galaxies. However, the detailed causal connections behind this relationship remain largely unknown. This is due in part to the complex diversity of active galactic nuclei (AGN) properties, the differing time-scales for AGN and star-forming processes, and a variety of observational selection effects. Physically, a prerequisite for both AGN activity and the formation of new stars in the host galaxy is the availability of gas. Environmental processes in galaxy clusters can strongly and rapidly affect gas reservoirs. Observations of star-forming galaxies in clusters have shown that the cluster environment drives evolution at a different rate than in the field. We here propose to make new measurements of the distribution of X-ray selected AGN, within cluster fields, and of their infrared (IR) and ultra-violet (UV) host galaxy properties to better understand the AGN triggering process, and the physical links between the SMBHs and their host galaxies. With a combination of superb spatial resolution and excellent sensitivity, Chandra X-ray observations have revolutionised studies of AGN evolution. The X-ray waveband is optimally suited for AGN surveys suffering little contamination from the host galaxy and only modest absorption bias, down to luminosities of 10^43 erg/s and across a wide range of source redshifts, providing direct access to a significant fraction of the total accretion power in the Universe (Brandt & Alexander 2015). However, two significant challenges exist that limit current studies of X-ray AGN in clusters: 1) the expense of optical follow-up of X-ray point source targets in order to confirm cluster membership; and 2) the low number of X-ray AGN that reside in clusters (typically 2-3 per cluster) relative to the background population (9,800 deg^2 in the deepest Chandra fields). In Ehlert et al. (2013, 2014 and 2015) we presented a

  18. The Star-Forming Properties of an Ultra-Hard X-ray Selected Sample of AGN

    NASA Astrophysics Data System (ADS)

    Shimizu, Thomas Taro; Mushotzky, Richard; Melendez, Marcio; Koss, Michael

    2015-08-01

    We present results from our Herschel follow-up survey of the Swift/BAT AGN 58 month catalog. Using the PACS and SPIRE instruments, 313 AGN were imaged at 5 far-infrared (FIR) wavelengths (70, 160, 250, 350, and 500 μm) producing the largest and most complete FIR catalog of local AGN. We combine our FIR photometry with archival mid-infrared photometry to form broadband spectral energy distributions (SEDs) that for the first time reach into the sub-millimeter regime. We fit these SEDs with several models to determine the star-forming properties of the host galaxies such as star-formation rate (SFR), IR luminosity, dust temperature, and dust mass and measure their relationship with various AGN properties such as X-ray luminosity, Eddington ratio, black hole mass, and column density. We find a weak dependence of the global SFR on the AGN strength indicating either the AGN has little influence on star formation over the entire galaxy or that the variability of the AGN on short timescales washes away any correlation between star formation and the AGN. Comparing the BAT AGN to a sample of normal star-forming galaxies on the “main sequence”, we find the BAT AGN systematically have decreased levels of specific SFR (sSFR = SFR/stellar mass). This is possibly indirect evidence that the AGN has suppressed star-formation in its host galaxy. Analysis of the FIR images themselves reveals that many of the BAT AGN are compact which leads to increased levels of SFR surface density, high enough for starburst driven winds. Finally, we show the 70 μm luminosity can be heavily contaminated by AGN emission and should not be used as a SFR indicator for AGN host galaxies.

  19. New light on obscured accretion in nearby AGN

    NASA Astrophysics Data System (ADS)

    Arevalo, Patricia

    Analyses of the Cosmic X-ray Background have shown that a substantial fraction of the black hole growth in the Universe occurred behind dense clouds of obscuring material. As such, it is critical to the study the detailed spectral characteristics of nearby obscured black holes, which provide templates for deriving accurate physical parameters from more distant obscured accretors. Hard X-rays are important in this regard, allowing us to peer more directly into the central engine of obscured sources and constrain the nature of the obscuration. The recently launched NuSTAR telescope is unique at focusing hard X-rays, producing the lowest background-contaminated spectra to date and rendering accurate, high signal-to-noise spectra up to 80 keV. NuSTAR covers precisely the energy range where the main features of obscured accretion appear and where the intrinsic emission might even shine through. Importantly, the low level of background also allows us for the first time to measure rapid variability of AGN at high X-ray energies. Both features combined are revealing the detailed nature of the engine of nearby obscured AGN, including the properties of the obscurer, the intrinsic emitted flux of the AGN and whether or not we can see through the torus at these high energies. In this talk I will show how NuSTAR data is challenging past assumptions about even the very local obscured AGN.

  20. A Model for Type 2 Coronal Line Forest (CLiF) AGNs

    NASA Astrophysics Data System (ADS)

    Glidden, Ana; Rose, Marvin; Elvis, Martin; McDowell, Jonathan

    2016-06-01

    We present a model for the classification of Coronal Line Forest Active Galactic Nuclei (CLiF AGNs). CLiF AGNs are of special interest due to their remarkably large number of emission lines, especially forbidden high-ionization lines (FHILs). Rose et al. suggest that their emission is dominated by reflection from the inner wall of the obscuring region rather than direct emission from the accretion disk. This makes CLiF AGNs laboratories to test AGN-torus models. Modeling an AGN as an accreting supermassive black hole surrounded by a cylinder of dust and gas, we show a relationship between the viewing angle and the revealed area of the inner wall. From the revealed area, we can determine the amount of FHIL emission at various angles. We calculate the strength of [Fe vii]λ6087 emission for a number of intermediate angles (30°, 40°, and 50°) and compare the results with the luminosity of the observed emission line from six known CLiF AGNs. We find that there is good agreement between our model and the observational results. The model also enables us to determine the relationship between the type 2:type 1 AGN fraction vs the ratio of torus height to radius, h/r.

  1. Multiwavelength AGN Surveys and Studies (IAU S304)

    NASA Astrophysics Data System (ADS)

    Mickaelian, Areg M.; Sanders, David B.

    2014-08-01

    1. Historical surveys: spectral and colorimetric surveys for AGN, surveys for UV-excess galaxies; 2. AGN from IR/submm surveys: 2MASS, IRAS, ISO, AKARI, SCUBA, SST, WISE, Herschel; 3. AGN from radio/mm surveys: NVSS, FIRST, ALMA, Planck, and others; 4. AGN from X-ray/gamma-ray surveys: ROSAT, ASCA, BeppoSAX, Chandra, XMM, INTEGRAL, Fermi, HESS, MAGIC, VERITAS, NuSTAR; 5. Multiwavelength AGN surveys, AGN statistics and cross-correlation of multiwavelength surveys; 6. Unification and other models of AGN, accretion modes, understanding of the structure of nearby AGN from IFUs on VLT and other telescopes; 7. AGN feedback in galaxies and clusters, AGN host galaxies and the AGN environments; 8. Binary AGN and Merging Super-Massive Black Holes; 9. Study of unique AGN, AGN variability and the Phenomena of Activity; 10. Future large projects; Author index.

  2. Increased left ventricular ejection fraction after a meal: potential source of error in performance of radionuclide angiography

    SciTech Connect

    Brown, J.M.; White, C.J.; Sobol, S.M.; Lull, R.J.

    1983-06-01

    The effect of a standardized meal on left ventricular (LV) ejection fraction (EF) was determined by equilibrium radionuclide angiography in 16 patients with stable congestive heart failure but without pulmonary or valvular heart disease. LVEF was determined in the fasting state and 15, 30, and 45 minutes after a meal. Patients with moderately depressed fasting LVEF (30 to 50%), Group I, had a mean increase of 6.9 +/- 2.9% (p less than 0.005) in the LVEF at 45 minutes after the meal. Patients with severely depressed fasting LVEF (less than 30%), Group II, had no change after the meal. It is concluded that significant increases in LVEF may occur after meals in patients with moderate but not severe left ventricular dysfunction. Equilibrium radionuclide angiography studies that are not standardized for patients' mealtimes may introduce an important unmeasured variable that will affect the validity of data in serial studies of left ventricular function.

  3. Detecting AGNs using multi-filter imaging data

    NASA Astrophysics Data System (ADS)

    Dong, Xiaoyi

    2012-05-01

    starforming/starburst galaxies (77.5%). Considering the accuracy of this technique, overall, 9-15% of galaxies in our sample should be considered as AGNs. 60 out of 178 AGNs were observed by the Sloan Digital Sky Survey (SDSS) spectral survey, which contains 11.3% of the SDSS main galaxy sample that overlapped with our sample. The number of AGNs detected by the neural net using photometric analysis alone is comparable to the number of AGNs identified by using SDSS spectra. We also developed a method to estimate the AGN to the host galaxy intensity (AGN-removed) ratio, br, using the galaxy light profile and colour information. The estimation is done by assuming that the "pure" AGN u -- r colour is 0.97, and the host galaxy colours are consistent within each T type. The internal reddenings used in the estimation were E(u -- r) = 0, 0.1, 0.2 mag. 35% of AGNs received a reasonable br estimation. The average r magnitude in our sample is about -19.3 mag, which is about 15% of the host galaxy intensity. Our technique achieved promising results. Some improvements that could be introduced in the future are: increase the size of the data sample, which in principle can improve the ANN performance, and also provide a sample of sufficient size to measure the AGN luminosity function; combine the ANN with other statistic tools such as Principal Component Analysis (PCA) and Monte-Carlo simulation, which also improves the ANN performance; improve shapelets realization for a faster computing speed and a more versatile application for a variety of shapes of objects.

  4. The Close AGN Reference Survey (CARS)

    NASA Astrophysics Data System (ADS)

    Rothberg, Barry; Husemann, Bernd; Busch, Gerold; Dierkes, Jens; Eckart, Andreas; Krajnovic, Davor; Scharwaechter, Julia; Tremblay, Grant R.; Urrutia, Tanya

    2015-08-01

    We present the first science results from the Close AGN Reference Survey (CARS). This program is a snapshot survey of 39 local type 1 AGN (0.01 < z <0.06) designed to address the issue of AGN-driven star formation quenching by characterizing the condition for star formation in AGN host galaxies. The primary sample was observed with Multi Unit Spectrscopic Explorer (MUSE), an optical wavelength integral field unit (IFU) with a 1'x1' field of view on the VLT. The optical 3D spectroscopy complements existing sub-mm CO(1-0) data and near-IR imaging to establish a unique dataset combining molecular and stellar masses with star formation rates, gas, stellar kinematics and AGN properties. The primary goals of CARS are to:1) investigate if the star formation efficiency and gas depletion time scales are suppressed as a consequence of AGN feedback; 2) identify AGN-driven outflows and their relation to the molecular gas reservoir of the host galaxy; 3) investigate the the balance of AGN feeding and feedback through the ratio of the gas reservoir to the AGN luminosity; and 4) provide the community with a reference survey of local AGN with a high legacy value. Future work will incorporate near-infrared IFU observations to present a complete spatially resolved picture of the interplay among AGN, star-formation, stellar populations, and the ISM.

  5. The Multiwavelength AGN Population and the X-ray Background

    NASA Astrophysics Data System (ADS)

    Treister, Ezequiel; Urry, Claudia M.; Schawinski, Kevin; Simmons, Brooke D.; Natarajan, Priyamvada; Volonteri, Marta

    2014-07-01

    In order to fully understand galaxy formation we need to know when in the cosmic history are supermassive black holes (SMBHs) growing more intensively, in what type of galaxies this growth is happening and what fraction of these sources are invisible at most wavelengths due to obscuration. Active Galactic Nuclei (AGN) population synthesis models that can explain the spectral shape and intensity of the cosmic X-ray background (CXRB) indicate that most of the SMBH growth occurs in moderate-luminosity (L X ~ 1044 erg/s) sources (Seyfert-type AGN), at z~ 0.5-1 and in heavily obscured but Compton-thin, NH ~ 1023cm-2, systems. However, this is not the complete history, as a large fraction of black hole growth does not emit significantly in X-rays either due to obscuration, intrinsic low luminosities or large distances. The integrated intensity at high energies indicates that a significant fraction of the total black hole growth, 22%, occurs in heavily-obscured systems that are not individually detected in even the deepest X-ray observations. We further investigate the AGN triggering mechanism as a function of bolometric luminosity, finding evidence for a strong connection between significant black hole growth events and major galaxy mergers from z~ 0 to z~ 3, while less spectacular but longer accretion episodes are most likely due to other (stochastic) processes. AGN activity triggered by major galaxies is responsible for ~60% of the total black hole growth. Finally, we constrain the total accreted mass density in supermassive black holes at z > 6, inferred via the upper limit derived from the integrated X-ray emission from a sample of photometrically selected galaxy candidates. We estimate an accreted mass density <1000 M⊙Mpc-3 at z~ 6, significantly lower than the previous predictions from some existing models of early black hole growth and earlier prior observations.

  6. The AGN Population and the Cosmic X-ray Background

    NASA Astrophysics Data System (ADS)

    Treister, Ezequiel; Urry, C. Meg; Schawinski, Kevin

    2015-08-01

    In order to fully understand galaxy formation we need to know when in the cosmic history are supermassive black holes (SMBHs) growing more intensively, in what type of galaxies this growth is happening and what fraction of these sources are invisible at most wavelengths due to obscuration. Active Galactic Nuclei (AGN) population synthesis models that can explain the spectral shape and intensity of the cosmic X-ray background (CXRB) indicate that most of the SMBH growth occurs in moderate-luminosity (Lx~1044 erg/s) sources (Seyfert-type AGN), at z~0.5-1 and in heavily obscured but Compton-thin, NH~1023 cm-2, systems.However, this is not the complete history, as a large fraction of black hole growth does not emit significantly in X-rays either due to obscuration, intrinsic low luminosities or large distances. Using a combination of X-ray stacking and multi wavelength selection techniques we constrain the amount of black hole accretion as a function of cosmic history, from z~0 to z~6. The integrated intensity at high energies indicates that a significant fraction of the total black hole growth, 22%, occurs in heavily-obscured systems that are not individually detected in even the deepest X-ray observations.We finally investigate the AGN triggering mechanism as a function of bolometric luminosity, finding evidence for a strong connection between significant black hole growth events and major galaxy mergers from z~0 to z~3, while less spectacular but longer accretion episodes are most likely due to other (stochastic) processes. AGN activity triggered by major galaxies is responsible for ~60% of the total black hole growth.

  7. Modification of aqueous enzymatic oil extraction to increase the yield of corn oil from dry fractionated corn germ

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In previous aqueous enzymatic extraction experiments we reported an oil yield of 67 grams from 800 grams of dry fractionated corn germ. In the current experiments, a dispersion of 10% cooked, dry-fractionated germ in water and was treated with amylases and a cellulase complex. A foam fraction was s...

  8. On the Importance of Very Light Internally Subsonic AGN Jets in Radio-mode AGN Feedback

    NASA Astrophysics Data System (ADS)

    Guo, Fulai

    2016-07-01

    Radio-mode active galactic nucleus (AGN) feedback plays a key role in the evolution of galaxy groups and clusters. Its physical origin lies in the kiloparsec-scale interaction of AGN jets with the intracluster medium. Large-scale jet simulations often initiate light internally supersonic jets with density contrast 0.01 < η < 1. Here we argue for the first time for the importance of very light (η < 0.01) internally subsonic jets. We investigated the shapes of young X-ray cavities produced in a suite of hydrodynamic simulations, and found that bottom-wide cavities are always produced by internally subsonic jets, while internally supersonic jets inflate cylindrical, center-wide, or top-wide cavities. We found examples of real cavities with shapes analogous to those inflated in our simulations by internally subsonic and internally supersonic jets, suggesting a dichotomy of AGN jets according to their internal Mach numbers. We further studied the long-term cavity evolution, and found that old cavities resulted from light jets spread along the jet direction, while those produced by very light jets are significantly elongated along the perpendicular direction. The northwestern ghost cavity in Perseus is pancake shaped, providing tentative evidence for the existence of very light jets. Our simulations show that very light internally subsonic jets decelerate faster and rise much slower in the intracluster medium than light internally supersonic jets, possibly depositing a larger fraction of jet energy to cluster cores and alleviating the problem of low coupling efficiencies found previously. The internal Mach number points to the jet’s energy content, and internally subsonic jets are energetically dominated by non-kinetic energy, such as thermal energy, cosmic rays, or magnetic fields.

  9. A SOFT X-RAY REVERBERATION LAG IN THE AGN ESO 113-G010

    SciTech Connect

    Cackett, E. M.; Fabian, A. C.; Kara, E.; Zogbhi, A.; Reynolds, C.; Uttley, P.

    2013-02-10

    Reverberation lags have recently been discovered in a handful of nearby, variable active galactic nuclei (AGNs). Here, we analyze a {approx}100 ks archival XMM-Newton observation of the highly variable AGN, ESO 113-G010, in order to search for lags between hard, 1.5-4.5 keV, and soft, 0.3-0.9 keV, energy X-ray bands. At the lowest frequencies available in the light curve ({approx}< 1.5 Multiplication-Sign 10{sup -4} Hz), we find hard lags where the power-law-dominated hard band lags the soft band (where the reflection fraction is high). However, at higher frequencies in the range (2-3) Multiplication-Sign 10{sup -4} Hz we find a soft lag of -325 {+-} 89 s. The general evolution from hard to soft lags as the frequency increases is similar to other AGNs where soft lags have been detected. We interpret this soft lag as due to reverberation from the accretion disk, with the reflection component responding to variability from the X-ray corona. For a black hole mass of 7 Multiplication-Sign 10{sup 6} M{sub Sun} this corresponds to a light-crossing time of {approx}9 R{sub g} /c; however, dilution effects mean that the intrinsic lag is likely longer than this. Based on recent black hole mass scaling for lag properties, the lag amplitude and frequency are more consistent with a black hole a few times more massive than the best estimates, though flux-dependent effects could easily add scatter this large.

  10. Searching for Dual AGNs in Galaxy Mergers: Understanding Double-Peaked [O III] and Ultra Hard X-rays as Selection Method

    NASA Astrophysics Data System (ADS)

    McGurk, Rosalie C.; Max, Claire E.; Medling, Anne; Shields, Gregory A.

    2015-01-01

    When galaxies merge, gas accretes onto both central supermassive black holes. Thus, one expects to see close pairs of active galactic nuclei (AGNs), or dual AGNs, in a fraction of galaxy mergers. However, finding them remains a challenge. The presence of double-peaked [O III] or of ultra hard X-rays have been proposed as techniques to select dual AGNs efficiently. We studied a sample of double-peaked narrow [O III] emitting AGNs from SDSS DR7. By obtaining new and archival high spatial resolution images taken with the Keck 2 Laser Guide Star Adaptive Optics system and the near-infrared (IR) camera NIRC2, we showed that 30% of double-peaked [O III] emission line SDSS AGNs have two spatial components within a 3' radius. However, spatially resolved spectroscopy or X-ray observations are needed to confirm these galaxy pairs as systems containing two AGNs. We followed up these spatially-double candidate dual AGNs with integral field spectroscopy from Keck OSIRIS and Gemini GMOS and with long-slit spectroscopy from Keck NIRSPEC and Shane Kast Double Spectrograph. We find double-peaked emitters are caused sometimes by dual AGN and sometimes by outflows or narrow line kinematics. We also performed Chandra X-ray ACIS-S observations on 12 double-peaked candidate dual AGNs. Using our observations and 8 archival observations, we compare the distribution of X-ray photons to our spatially double near-IR images, measure X-ray luminosities and hardness ratios, and estimate column densities. By assessing what fraction of double-peaked emission line SDSS AGNs are true dual AGNs, we can better determine whether double-peaked [O III] is an efficient dual AGN indicator and constrain the statistics of dual AGNs. A second technique to find dual AGN is the detection of ultra hard X-rays by the Swift Burst Alert Telescope. We use CARMA observations to measure and map the CO(1-0) present in nearby ultra-hard X-ray Active Galactic Nuclei (AGNs) merging with either a quiescent companion

  11. RXTE observations of AGN

    NASA Technical Reports Server (NTRS)

    Rothschild, R. E.; Heindl, W. A.; Blanco, P. R.; Gruber, D. E.; Marsden, D. C.; Pelling, M. R.; Jahoda, K.; Madejski, G.; Swank, J. H.; Zdziarski, A. A.; Gierlinski, M.; Hink, P. L.

    1997-01-01

    The Rossi X-ray Timing Explorer (RXTE) observed three active galaxies during its in-orbit verification phase: NGC 4151; NGC 4945, and MCG 8-11-11. All three were detected from 2 keV to more than 100 keV by a combination of the proportional counter array (PCA) and the high energy X-ray timing experiment (HEXTE). The PCA contains five, xenon/methane, multilayer, multiwire, gas proportional counters covering the 2 to 60 keV range, while HEXTE is an array of eight NaI/CsI phoswich scintillation counters covering the 15 to 250 keV range. The three active galaxies represent the classes of Seyfert 1, Seyfert 2 and intermediate Seyfert galaxies. The results of the fitting of various models containing partial covering fractions, Compton reflection components and high energy spectral breaks are discussed.

  12. AGNs with composite spectra.

    NASA Astrophysics Data System (ADS)

    Veron, P.; Goncalves, A. C.; Veron-Cetty, M.-P.

    1997-03-01

    The use of the Baldwin et al. (1981PASP...93....5B) or Veilleux & Osterbrock (1987ApJS...63..295V) diagnostic diagrams allows the unambiguous classification of the nuclear emission line regions of most galaxies into one of three categories: nuclear HII regions or starbursts, Seyfert 2 galaxies and Liners. However, a small fraction of them have a "transition" spectrum. We present spectral observations of 15 "transition" objects at high-dispersion (66Å/mm) around the Hα, [NII]λλ6548,6584 and/or Hβ, [OIII]λλ4959,5007 emission lines. We show that most of these spectra are composite, due to the simultaneous presence on the slit of a Seyfert nucleus and a HII region. Seyfert 2s and Liners seem to occupy relatively small and distinct volumes in the three-dimensional space λ5007/Hβ, λ6584/Hα, λ6300/Hα.

  13. A spectroscopic survey of X-ray-selected AGNs in the northern XMM-XXL field

    NASA Astrophysics Data System (ADS)

    Menzel, M.-L.; Merloni, A.; Georgakakis, A.; Salvato, M.; Aubourg, E.; Brandt, W. N.; Brusa, M.; Buchner, J.; Dwelly, T.; Nandra, K.; Pâris, I.; Petitjean, P.; Schwope, A.

    2016-03-01

    This paper presents a survey of X-ray-selected active galactic nuclei (AGNs) with optical spectroscopic follow-up in a ˜ 18 deg2 area of the equatorial XMM-XXL north field. A sample of 8445 point-like X-ray sources detected by XMM-Newton above a limiting flux of F_{0.5-10 keV} > 10^{-15} erg cm^{-2} s^{-1} was matched to optical (Sloan Digital Sky Survey, SDSS) and infrared (IR; WISE) counterparts. We followed up 3042 sources brighter than r = 22.5 mag with the SDSS Baryon Oscillation Spectroscopic Survey (BOSS) spectrograph. The spectra yielded a reliable redshift measurement for 2578 AGNs in the redshift range z = 0.02-5.0, with 0.5-2 keV luminosities ranging from 1039-1046 erg s- 1. This is currently the largest published spectroscopic sample of X-ray-selected AGNs in a contiguous area. The BOSS spectra of AGN candidates show a distribution of optical line widths which is clearly bimodal, allowing an efficient separation between broad- and narrow-emission line AGNs. The former dominate our sample (70 per cent) due to the relatively bright X-ray flux limit and the optical BOSS magnitude limit. We classify the narrow-emission line objects (22 per cent of the full sample) using standard optical emission line diagnostics: the majority have line ratios indicating the dominant source of ionization is the AGN. A small number (8 per cent of the full sample) exhibit the typical narrow line ratios of star-forming galaxies, or only have absorption lines in their spectra. We term the latter two classes `elusive' AGN, which would not be easy to identify correctly without their X-ray emission. We also compare X-ray (XMM-Newton), optical colour (SDSS) and and IR (WISE) AGN selections in this field. X-ray observations reveal, by far, the largest number of AGN. The overlap between the selections, which is a strong function of the imaging depth in a given band, is also remarkably small. We show using spectral stacking that a large fraction of the X-ray AGNs would not be

  14. Stellar and quasar feedback in concert: effects on AGN accretion, obscuration, and outflows

    NASA Astrophysics Data System (ADS)

    Hopkins, Philip F.; Torrey, Paul; Faucher-Giguère, Claude-André; Quataert, Eliot; Murray, Norman

    2016-05-01

    We study the interaction of feedback from active galactic nuclei (AGN) and a multiphase interstellar medium (ISM), in simulations including explicit stellar feedback, multiphase cooling, accretion-disc winds, and Compton heating. We examine radii ˜0.1-100 pc around a black hole (BH), where the accretion rate on to the BH is determined and where AGN-powered winds and radiation couple to the ISM. We conclude: (1) the BH accretion rate is determined by exchange of angular momentum between gas and stars in gravitational instabilities. This produces accretion rates ˜0.03-1 M⊙ yr-1, sufficient to power luminous AGN. (2) The gas disc in the galactic nucleus undergoes an initial burst of star formation followed by several million years where stellar feedback suppresses the star formation rate (SFR). (3) AGN winds injected at small radii with momentum fluxes ˜LAGN/c couple efficiently to the ISM and have dramatic effects on ISM properties within ˜100 pc. AGN winds suppress the nuclear SFR by factors ˜10-30 and BH accretion rate by factors ˜3-30. They increase the outflow rate from the nucleus by factors ˜10, consistent with observational evidence for galaxy-scale AGN-driven outflows. (4) With AGN feedback, the predicted column density distribution to the BH is consistent with observations. Absent AGN feedback, the BH is isotropically obscured and there are not enough optically thin sightlines to explain type-I AGN. A `torus-like' geometry arises self-consistently as AGN feedback evacuates gas in polar regions.

  15. Non-thermal AGN models

    SciTech Connect

    Band, D.L.

    1986-12-01

    The infrared, optical and x-ray continua from radio quiet active galactic nuclei (AGN) are explained by a compact non-thermal source surrounding a thermal ultraviolet emitter, presumably the accretion disk around a supermassive black hole. The ultraviolet source is observed as the ''big blue bump.'' The flat (..cap alpha.. approx. = .7) hard x-ray spectrum results from the scattering of thermal ultraviolet photons by the flat, low energy end of an electron distribution ''broken'' by Compton losses; the infrared through soft x-ray continuum is the synchrotron radiation of the steep, high energy end of the electron distribution. Quantitative fits to specific AGN result in models which satisfy the variability constraints but require electron (re)acceleration throughout the source. 11 refs., 1 fig.

  16. Comparing Simulations of AGN Feedback

    NASA Astrophysics Data System (ADS)

    Richardson, Mark L. A.; Scannapieco, Evan; Devriendt, Julien; Slyz, Adrianne; Thacker, Robert J.; Dubois, Yohan; Wurster, James; Silk, Joseph

    2016-07-01

    We perform adaptive mesh refinement (AMR) and smoothed particle hydrodynamics (SPH) cosmological zoom simulations of a region around a forming galaxy cluster, comparing the ability of the methods to handle successively more complex baryonic physics. In the simplest, non-radiative case, the two methods are in good agreement with each other, but the SPH simulations generate central cores with slightly lower entropies and virial shocks at slightly larger radii, consistent with what has been seen in previous studies. The inclusion of radiative cooling, star formation, and stellar feedback leads to much larger differences between the two methods. Most dramatically, at z=5, rapid cooling in the AMR case moves the accretion shock to well within the virial radius, while this shock remains near the virial radius in the SPH case, due to excess heating, coupled with poorer capturing of the shock width. On the other hand, the addition of feedback from active galactic nuclei (AGNs) to the simulations results in much better agreement between the methods. For our AGN model, both simulations display halo gas entropies of 100 keV cm2, similar decrements in the star formation rate, and a drop in the halo baryon content of roughly 30%. This is consistent with the AGN growth being self-regulated, regardless of the numerical method. However, the simulations with AGN feedback continue to differ in aspects that are not self-regulated, such that in SPH a larger volume of gas is impacted by feedback, and the cluster still has a lower entropy central core.

  17. The Importance of Winds for AGN Feedback

    NASA Astrophysics Data System (ADS)

    Crenshaw, D. M.; Kraemer, S. B.; Schmitt, H. R.; Fischer, T. C.; Gagne, J.

    2014-01-01

    Active galactic nuclei (AGN) are fed by accretion of matter onto supermassive black holes (SMBHs), generating huge amounts of radiation from very small volumes. AGN also provide feedback to their environments via mass outflows of ionized gas, which could play a critical role in the formation of large-scale structure in the early Universe, chemical enrichment of the intergalactic medium, and self-regulation of SMBH and galactic bulge growth. We provide an update on our research on the winds in nearby moderate-luminosity AGN, In particular, we concentrate on winds that occur on relatively large scales (hundreds of parsecs) that are revealed through spatially resolved HST spectra of emission-line gas in the narrow line regions (NLRs) of nearby AGN. We discuss the techniques for measuring the mass outflow rates and kinetic luminosities of these AGN winds and gauge their importance for providing significant AGN feedback.

  18. New insights into AGN coronae

    NASA Astrophysics Data System (ADS)

    Lohfink, Anne; Fabian, Andrew C.; Malzac, Julien; Belmont, Renaud; Buisson, Douglas

    2016-04-01

    Active galactic nuclei (AGN) are some of the most energetic sources of radiation in the Universe. The conversion of gravitational energy into radiation is thought to take place in an accretion disk/corona system just outside the black hole. In this system thermal, UV/optical photons from the accretion disk are upscattered in a corona of hot electrons situated above the accretion disk producing X-rays. The nature of this Comptonizing corona remains a key open question in AGN physics. The NuSTAR satellite provides the opportunity to study the Comptonization spectrum produced by the corona in great detail. In our talk we will show some key results from these new studies of the Comptonization spectrum. We explore how, together with our growing knowledge of coronal sizes, we are able to draw first conclusions about the physics taking place in the corona. We find evidence for coronae to be hot and radiatively compact, putting them close to the boundary of the region in the compactness-temperature diagram which is forbidden due to runaway pair production. This suggests that pair production and annihilation are essential ingredients in the coronae of AGN and that they control the coronal temperature and shape of the observed spectra.

  19. PRIMUS: THE DEPENDENCE OF AGN ACCRETION ON HOST STELLAR MASS AND COLOR

    SciTech Connect

    Aird, James; Coil, Alison L.; Moustakas, John; Smith, M. Stephen M.; Blanton, Michael R.; Zhu Guangtun; Burles, Scott M.; Cool, Richard J.; Eisenstein, Daniel J.; Wong, Kenneth C.

    2012-02-10

    We present evidence that the incidence of active galactic nuclei (AGNs) and the distribution of their accretion rates do not depend on the stellar masses of their host galaxies, contrary to previous studies. We use hard (2-10 keV) X-ray data from three extragalactic fields (XMM-LSS, COSMOS, and ELAIS-S1) with redshifts from the Prism Multi-object Survey to identify 242 AGNs with L{sub 2-10keV} = 10{sup 42-44} erg s{sup -1} within a parent sample of {approx}25,000 galaxies at 0.2 < z < 1.0 over {approx}3.4 deg{sup 2} and to i {approx} 23. We find that although the fraction of galaxies hosting an AGN at fixed X-ray luminosity rises strongly with stellar mass, the distribution of X-ray luminosities is independent of mass. Furthermore, we show that the probability that a galaxy will host an AGN can be defined by a universal Eddington ratio distribution that is independent of the host galaxy stellar mass and has a power-law shape with slope -0.65. These results demonstrate that AGNs are prevalent at all stellar masses in the range 9.5< log M{sub *}/M{sub sun}<12 and that the same physical processes regulate AGN activity in all galaxies in this stellar mass range. While a higher AGN fraction may be observed in massive galaxies, this is a selection effect related to the underlying Eddington ratio distribution. We also find that the AGN fraction drops rapidly between z {approx} 1 and the present day and is moderately enhanced (factor {approx}2) in galaxies with blue or green optical colors. Consequently, while AGN activity and star formation appear to be globally correlated, we do not find evidence that the presence of an AGN is related to the quenching of star formation or the color transformation of galaxies.

  20. A Degeneracy in DRW Modelling of AGN Light Curves

    NASA Astrophysics Data System (ADS)

    Kozłowski, Szymon

    2016-04-01

    Individual light curves of active galactic nuclei (AGNs) are nowadays successfully modelled with the damped random walk (DRW) stochastic process, characterized by the power exponential covariance matrix of the signal, with the power β = 1. By Monte Carlo simulation means, we generate mock AGN light curves described by non-DRW stochastic processes (0.5 ≤ β ≤ 1.5 and β ≠ 1) and show they can be successfully and well-modelled as a single DRW process, obtaining comparable goodness of fits. A good DRW fit, in fact, may not mean that DRW is the true underlying process leading to variability and it cannot be used as a proof for it. When comparing the input (non-DRW) and measured (DRW) process parameters, the recovered time scale (amplitude) increases (decreases) with the increasing input β. In practice, this means that the recovered DRW parameters may lead to biased (or even non-existing) correlations of the variability and physical parameters of AGNs if the true AGN variability is caused by non-DRW stochastic processes. The proper way of identifying the processes leading to variability are model-independent structure functions and/or power spectral densities and then using such information on the covariance matrix of the signal in light curve modelling.

  1. A degeneracy in DRW modelling of AGN light curves

    NASA Astrophysics Data System (ADS)

    Kozłowski, Szymon

    2016-07-01

    Individual light curves of active galactic nuclei (AGNs) are nowadays successfully modelled with the damped random walk (DRW) stochastic process, characterized by the power exponential covariance matrix of the signal, with the power β = 1. By Monte Carlo simulation means, we generate mock AGN light curves described by non-DRW stochastic processes (0.5 ≤ β ≤ 1.5 and β ≠ 1) and show they can be successfully and well modelled as a single DRW process, obtaining comparable goodness of fits. A good DRW fit, in fact, may not mean that DRW is the true underlying process leading to variability and it cannot be used as a proof for it. When comparing the input (non-DRW) and measured (DRW) process parameters, the recovered time-scale (amplitude) increases (decreases) with the increasing input β. In practice, this means that the recovered DRW parameters may lead to biased (or even non-existing) correlations of the variability and physical parameters of AGNs if the true AGN variability is caused by non-DRW stochastic processes. The proper way of identifying the processes leading to variability are model-independent structure functions and/or power spectral densities and then using such information on the covariance matrix of the signal in light-curve modelling.

  2. AGN Feedback in Overdense Environments at z=2.23

    NASA Astrophysics Data System (ADS)

    Lucy, Adrian B.; Lehmer, B.; Alexander, D. M.; Best, P.; Geach, J.; Harrison, C. M.; Hornschemeier, A. E.; Matsuda, Y.; Mullaney, J.; Smail, I.; Sobral, D.

    2013-01-01

    We present results from a ≈100 ks Chandra observation of the 2QZ Cluster 1004+00 galaxy overdensity at z=2.23. This 2QZ Clus structure was first identified as an overdensity of four optically-selected quasars; that sample was subsequently found to overlap with an overdensity of 22 Hα-emitting galaxies (HAEs) identified through narrow and broad band near-infrared imaging by Matsuda et al. (2011). In addition to the preselected quasars in 2QZ Clus, our Chandra observation reveals that a further three HAEs are X-ray sources, all characterized by X-ray luminosities and spectral slopes consistent with unobscured active galactic nuclei (AGN). In total, we find that ≈30% of HAEs in our observed region of 2QZ Clus are AGN. This AGN fraction is high compared to AGN fractions among HAEs in the Chandra-COSMOS field (C-COSMOS), and if this enhancement is purely a result of the quasar selection bias of our sample, we estimate that such activity is rare at this redshift. Hα is a tracer of star formation, so 2QZ Clus is well suited to the investigation of the coeval growth of supermassive black holes and their host galaxies in the precursors to rich local clusters. Moreover, we have an ideal control sample in C-COSMOS; this survey contains a large sample of HAEs classified identically using infrared imaging, but without any selection of quasars. We calculate AGN fraction as a function of galaxy overdensity in C-COSMOS, and perform stacking analyses of Chandra and 250μ Herschel SPIRE data to obtain mean black hole accretion rates dMBH/dt and star formation rates SFR. Preliminary results indicate that dMBH/dt and its ratio to SFR are significantly elevated in 2QZ Clus compared to similarly overdense regions of C-COSMOS. We discuss these relations in the context of theoretical models describing the emergence of the MBH/Mgal relation of the local Universe.

  3. Probing AGN Unification with galaxy neighbours: pitfalls and prospects

    NASA Astrophysics Data System (ADS)

    Villarroel, B.

    2015-09-01

    Statistical tests of AGN unification harbour many caveats. One way of constraining the validity of the AGN unification is through studies of close neighbours to Type-1 and Type-2 AGN. Examining thousands of AGN- galaxy pairs from the Sloan Digital Sky Survey Data Release 7 and the Galaxy Zoo project, we found that Type-2 AGN appear to reside in more star-forming environments than Type-1 AGN.

  4. The star formation-AGN interplay in merging galaxies: insights from hydrodynamical simulations and observations.

    NASA Astrophysics Data System (ADS)

    Martinez Galarza, Juan R.; Smith, Howard Alan; Weiner, Aaron; Hayward, Christopher C.; Lanz, Lauranne; Zezas, Andreas; Rosenthal, Lee; Ashby, Matthew

    2016-01-01

    Thermal emission from an Active Galactic Nucleus (AGN) can provide a significant contribution to the bolometric luminosity of galaxies, and its effect at infrared wavelengths can mimic the process of star-formation, jeopardizing star formation rate (SFR) diagnostics. It is therefore important to model the AGN emission and to quantify its effect on the estimated SFRs when SED fitting tools are applied. We tackle this problem by studying the dust radiative transfer calculations of hydrodynamically simulated binary galaxy mergers covering a broad range of parameters, including stellar mas ratios, gas contents, AGN luminosity and viewing angles. We apply the energy balance SED fitting codes CHIBURST and CIGALE to the mock SEDs of our simulated merger, and then compare with the results of applying the same codes to the SEDs of observed merging galaxies in the Local Universe. At different stages of the interaction, we compare their derived SFRs and AGN fractions with those predicted by the hydrodynamical simulations, for a broad range of the interaction parameters, but focus on the stages near coalescence, when the AGN contribution exceed 10% of the total luminosity. We show that the contribution to IR luminosity is greatest during and immediately after coalescence, when the two supermassive black holes of the interacting pair merge and undergo and enhanced period of accretion. Under certain conditions, CIGALE succeeds at recovering the SFRs and AGN fractions with higher accuracy than other available codes, such as MAGPHYS, even during these extreme stages. Our results show that using the IR luminosity as a simple surrogate for star formation can significantly overestimate the true SFR by underestimating the contribution from the AGN. Finally, we study the effect of using different parametric star formation histories (SFHs) when fitting the SEDs of galaxies, and show that a delayed SFH is usually a reasonable choice for merging galaxies.

  5. AGN POPULATION IN HICKSON COMPACT GROUPS. I. DATA AND NUCLEAR ACTIVITY CLASSIFICATION

    SciTech Connect

    MartInez, M. A.; Del Olmo, A.; Perea, J.; Coziol, R. E-mail: chony@iaa.es E-mail: rcoziol@astro.ugto.mx

    2010-03-15

    We have conducted a new spectroscopic survey to characterize the nature of nuclear activity in Hickson compact group (HCG) galaxies and establish its frequency. We have obtained new intermediate-resolution optical spectroscopy for 200 member galaxies and corrected for underlying stellar population contamination using galaxy templates. Spectra for 11 additional galaxies have been acquired from the ESO and 6dF public archives, and emission-line ratios have been taken from the literature for 59 more galaxies. Here we present the results of our classification of the nuclear activity for 270 member galaxies, which belong to a well-defined sample of 64 HCGs. We found a large fraction of galaxies, 63%, with emission lines. Using standard diagnostic diagrams, 45% of the emission-line galaxies were classified as pure active galactic nuclei (AGNs), 23% as Transition Objects (TOs), and 32% as star-forming nuclei (SFNs). In the HCGs, the AGN activity appears as the most frequent activity type. Adopting the interpretation that in TOs a low-luminosity AGN coexists with circumnuclear star formation, the fraction of galaxies with an AGN could rise to 42% of the whole sample. The low frequency (20%) of SFNs confirms that there is no star formation enhancement in HCGs. After extinction correction, we found a median AGN H{alpha} luminosity of 7.1 x 10{sup 39} erg s{sup -1}, which implies that AGNs in HCG have a characteristically low luminosity. This result added to the fact that there is an almost complete absence of broad-line AGNs in compact groups (CGs) as found by MartInez et al. and corroborated in this study for HCGs, is consistent with very few gas left in these galaxies. In general, therefore, what may characterize the level of activity in CGs is a severe deficiency of gas.

  6. AGN Population in Hickson Compact Groups. I. Data and Nuclear Activity Classification

    NASA Astrophysics Data System (ADS)

    Martínez, M. A.; Del Olmo, A.; Coziol, R.; Perea, J.

    2010-03-01

    We have conducted a new spectroscopic survey to characterize the nature of nuclear activity in Hickson compact group (HCG) galaxies and establish its frequency. We have obtained new intermediate-resolution optical spectroscopy for 200 member galaxies and corrected for underlying stellar population contamination using galaxy templates. Spectra for 11 additional galaxies have been acquired from the ESO and 6dF public archives, and emission-line ratios have been taken from the literature for 59 more galaxies. Here we present the results of our classification of the nuclear activity for 270 member galaxies, which belong to a well-defined sample of 64 HCGs. We found a large fraction of galaxies, 63%, with emission lines. Using standard diagnostic diagrams, 45% of the emission-line galaxies were classified as pure active galactic nuclei (AGNs), 23% as Transition Objects (TOs), and 32% as star-forming nuclei (SFNs). In the HCGs, the AGN activity appears as the most frequent activity type. Adopting the interpretation that in TOs a low-luminosity AGN coexists with circumnuclear star formation, the fraction of galaxies with an AGN could rise to 42% of the whole sample. The low frequency (20%) of SFNs confirms that there is no star formation enhancement in HCGs. After extinction correction, we found a median AGN Hα luminosity of 7.1 × 1039 erg s-1, which implies that AGNs in HCG have a characteristically low luminosity. This result added to the fact that there is an almost complete absence of broad-line AGNs in compact groups (CGs) as found by Martínez et al. and corroborated in this study for HCGs, is consistent with very few gas left in these galaxies. In general, therefore, what may characterize the level of activity in CGs is a severe deficiency of gas.

  7. Effectiveness of WISE colour-based selection techniques to uncover obscured AGN

    NASA Astrophysics Data System (ADS)

    Mateos, S.

    2014-07-01

    We present a highly reliable and efficient mid-infrared colour-based selection technique for luminous active galactic nuclei (AGN) using the Wide-field Infrared Survey Explorer (WISE) survey. Our technique is designed to identify objects with red mid-infrared power-law spectral energy distributions. We studied the dependency of our mid-infrared selection on the AGN intrinsic luminosity and the effectiveness of our technique to uncover obscured AGN missed in X-ray surveys. To do so we used two samples of luminous AGN independently selected in hard X-ray and optical surveys. We used the largest catalogue of 887 [OIII] λ5007-selected type 2 quasars (QSO2s) at z<~0.83 in the literature from the Sloan Digital Sky Survey (SDSS), and the 258 hard (>4.5 keV) X-ray-selected AGN from the Bright Ultrahard XMM-Newton Survey (BUXS). The effectiveness of our mid-infrared selection technique increases with the AGN luminosity. At high luminosities and at least up to z~1 our technique is very effective at identifying both Compton-thin and Compton-thick AGN.

  8. The Contribution of Compton-Thick AGN/ULIRGs to the X-Ray Background

    NASA Astrophysics Data System (ADS)

    Nardini, Emanuele

    fraction of the obscured AGN population. Their broadband spectral energy distribution can then be used to calibrate new photometric diagnostics based on mid-IR colors and bolometric corrections, capable of selecting their faint counterparts within the IR deep fields. The wealth of data in the WISE and Spitzer archives will allow a complete census of this AGN subclass. The reflection efficiency inferred from our new Suzaku observations will make it possible to address from a quantitative point of view the issue of the Compton-thick AGN/ULIRG contributon to the X-ray background.

  9. High precision X-ray log N - log S distributions: implications for the obscured AGN population

    NASA Astrophysics Data System (ADS)

    Mateos, S.; Warwick, R. S.; Carrera, F. J.; Stewart, G. C.; Ebrero, J.; Della Ceca, R.; Caccianiga, A.; Gilli, R.; Page, M. J.; Treister, E.; Tedds, J. A.; Watson, M. G.; Lamer, G.; Saxton, R. D.; Brunner, H.; Page, C. G.

    2008-12-01

    source count distributions than AGN. We find a substantial increase in the relative fraction of hard X-ray sources at higher energies, from ≥55% below 2 keV to ≥77% above 2 keV. However, the majority of sources detected above 4.5 keV still have significant flux below 2 keV. Comparison with predictions from the synthesis models suggest that the models might be overpredicting the number of faint absorbed AGN, which would call for fine adjustment of some model parameters such as the obscured to unobscured AGN ratio and/or the distribution of column densities at intermediate obscuration. Appendices A and B are only available in electronic form at http://www.aanda.org

  10. SWIFT BAT Survey of AGN

    NASA Technical Reports Server (NTRS)

    Tueller, J.; Mushotzky, R. F.; Barthelmy, S.; Cannizzo, J. K.; Gehrels, N.; Markwardt, C. B.; Skinner, G. K.; Winter, L. M.

    2008-01-01

    We present the results1 of the analysis of the first 9 months of data of the Swift BAT survey of AGN in the 14-195 keV band. Using archival X-ray data or follow-up Swift XRT observations, we have identified 129 (103 AGN) of 130 objects detected at [b] > 15deg and with significance > 4.8-delta. One source remains unidentified. These same X-ray data have allowed measurement of the X-ray properties of the objects. We fit a power law to the logN - log S distribution, and find the slope to be 1.42+/-0.14. Characterizing the differential luminosity function data as a broken power law, we find a break luminosity logL*(ergs/s)= 43.85+/-0.26. We obtain a mean photon index 1.98 in the 14-195 keV band, with an rms spread of 0.27. Integration of our luminosity function gives a local volume density of AGN above 10(exp 41) erg/s of 2.4x10(exp -3) Mpc(sup -3), which is about 10% of the total luminous local galaxy density above M* = -19.75. We have obtained X-ray spectra from the literature and from Swift XRT follow-up observations. These show that the distribution of log nH is essentially flat from nH = 10(exp 20)/sq cm to 10(exp 24)/sq cm, with 50% of the objects having column densities of less than 10(exp 22)/sq cm. BAT Seyfert galaxies have a median redshift of 0.03, a maximum log luminosity of 45.1, and approximately half have log nH > 22.

  11. Early Idiopathic Normal Pressure Hydrocephalus Patients With Neuropsychological Impairment Are Associated With Increased Fractional Anisotropy in the Anterior Thalamic Nucleus.

    PubMed

    Chen, Yung-Chieh; Chiang, Shih-Wei; Chi, Chia-Hsing; Liou, Michelle; Kuo, Duen-Pang; Kao, Hung-Wen; Chung, Hsiao-Wen; Ma, Hsin I; Peng, Giia-Sheun; Wu, Yu-Te; Chen, Cheng-Yu

    2016-05-01

    In this study, we aimed to investigate the reactive changes in diffusion tensor imaging (DTI)-derived diffusion metrics of the anterior thalamic nucleus (AN), a relaying center for the Papez circuit, in early idiopathic normal pressure hydrocephalus (iNPH) patients with memory impairment, as well as its correlation with the patients' neuropsychological performances. In total, 28 probable iNPH patients with symptom onset within 1 year and 17 control subjects were prospectively recruited between 2010 and 2013 for this institutional review board-approved study. Imaging studies including DTI and a neuropsychological assessment battery were performed in all subjects. Diffusion metrics were measured from the region of the AN using tract-deterministic seeding method by reconstructing the mammillo-thalamo-cingulate connections within the Papez circuit. Differences in diffusion metrics and memory assessment scores between the patient and control group were examined via the Mann-Whitney U test. Spearman correlation analyses were performed to examine associations between diffusion metrics of AN and neuropsychological tests within the patient group. We discovered that early iNPH patients exhibited marked elevations in fractional anisotropy, pure diffusion anisotropy, and axial diffusivity (all P < 0.01), as well as lower neuropsychological test scores including verbal and nonverbal memory (all P < 0.05) compared with normal control. Spearman rank correlation analyses did not disclose significant correlations between AN diffusion metrics and neuropsychological test scores in the patient group, whereas ranked scatter plots clearly demonstrated a dichotic sample distribution between patient and control samples. In summary, our study highlighted the potential compensatory role of the AN by increasing thalamocortical connectivity within the Papez circuit because memory function declines in early iNPH when early shunt treatment may potentially reverse the memory deficits

  12. Early Idiopathic Normal Pressure Hydrocephalus Patients With Neuropsychological Impairment Are Associated With Increased Fractional Anisotropy in the Anterior Thalamic Nucleus

    PubMed Central

    Chen, Yung-Chieh; Chiang, Shih-Wei; Chi, Chia-Hsing; Liou, Michelle; Kuo, Duen-Pang; Kao, Hung-Wen; Chung, Hsiao-Wen; Ma, Hsin I.; Peng, Giia-Sheun; Wu, Yu-Te; Chen, Cheng-Yu

    2016-01-01

    Abstract In this study, we aimed to investigate the reactive changes in diffusion tensor imaging (DTI)-derived diffusion metrics of the anterior thalamic nucleus (AN), a relaying center for the Papez circuit, in early idiopathic normal pressure hydrocephalus (iNPH) patients with memory impairment, as well as its correlation with the patients’ neuropsychological performances. In total, 28 probable iNPH patients with symptom onset within 1 year and 17 control subjects were prospectively recruited between 2010 and 2013 for this institutional review board-approved study. Imaging studies including DTI and a neuropsychological assessment battery were performed in all subjects. Diffusion metrics were measured from the region of the AN using tract-deterministic seeding method by reconstructing the mammillo–thalamo–cingulate connections within the Papez circuit. Differences in diffusion metrics and memory assessment scores between the patient and control group were examined via the Mann–Whitney U test. Spearman correlation analyses were performed to examine associations between diffusion metrics of AN and neuropsychological tests within the patient group. We discovered that early iNPH patients exhibited marked elevations in fractional anisotropy, pure diffusion anisotropy, and axial diffusivity (all P < 0.01), as well as lower neuropsychological test scores including verbal and nonverbal memory (all P < 0.05) compared with normal control. Spearman rank correlation analyses did not disclose significant correlations between AN diffusion metrics and neuropsychological test scores in the patient group, whereas ranked scatter plots clearly demonstrated a dichotic sample distribution between patient and control samples. In summary, our study highlighted the potential compensatory role of the AN by increasing thalamocortical connectivity within the Papez circuit because memory function declines in early iNPH when early shunt treatment may potentially reverse the

  13. Obscuring Fraction of Active Galactic Nuclei: Implications from Radiation-driven Fountain Models

    NASA Astrophysics Data System (ADS)

    Wada, Keiichi

    2015-10-01

    Active galactic nuclei (AGNs) are believed to be obscured by an optical thick “torus” that covers a large fraction of solid angles for the nuclei. However, the physical origin of the tori and the differences in the tori among AGNs are not clear. In a previous paper based on three-dimensional radiation-hydorodynamic calculations, we proposed a physics-based mechanism for the obscuration, called “radiation-driven fountains,” in which the circulation of the gas driven by central radiation naturally forms a thick disk that partially obscures the nuclear emission. Here, we expand this mechanism and conduct a series of simulations to explore how obscuration depends on the properties of AGNs. We found that the obscuring fraction fobs for a given column density toward the AGNs changes depending on both the AGN luminosity and the black hole mass. In particular, fobs for NH ≥ 1022 cm-2 increases from ˜0.2 to ˜0.6 as a function of the X-ray luminosity LX in the LX = 1042-44 erg s-1 range, but fobs becomes small (˜0.4) above a luminosity (˜1045 erg s-1). The behaviors of fobs can be understood by a simple analytic model and provide insight into the redshift evolution of the obscuration. The simulations also show that for a given LAGN, fobs is always smaller (˜0.2-0.3) for a larger column density (NH ≥ 1023 cm-2). We also found cases that more than 70% of the solid angles can be covered by the fountain flows.

  14. AGN Winds and Blazar Phenomenology

    NASA Technical Reports Server (NTRS)

    Kazanas, Demos

    2012-01-01

    The launch of {\\em Fermi} produced a significant number of AGN detections to allow statistical treatment of their properties. One of the first such systematics was the "Blazar Divide" in FSRQs and BL Lacs according to their gamma-ray spectral index and luminosity. Further data accumulation indicated this separation to be less clear than thought before. An MHD wind model which can model successfully the Seyfert X-ray absorber properties provides the vestiges of an account of the observed blazar classification. We propose to employ this model to model in detail the broad band blazar spectra and their statistical properties in terms of the physical parameters of these MHD winds.

  15. Type 1 AGN at low z. I. Emission properties

    NASA Astrophysics Data System (ADS)

    Stern, J.; Laor, A.

    2012-07-01

    We analyze the emission properties of a new sample of 3 596 type 1 AGN, selected from the SDSS DR7 based on the detection of broad Hα emission. The sample extends over a broad Hα luminosity LbHα of 1040-1044 erg s-1 and a broad Hα FWHM of 1 000-25 000 km s-1, which covers the range of black hole mass 106 < MBH/Modot < 109.5 and luminosity in Eddington units 10-3 < L/LEdd < 1. We combine ROSAT, GALEX and 2MASS observations to form the SED from 2.2 μm to 2 keV. We find the following: 1. The distribution of the Hα FWHM values is independent of luminosity. 2. The observed mean optical-UV SED is well matched by a fixed shape SED of luminous quasars, which scales linearly with LbHα, and a host galaxy contribution. 3. The host galaxy r-band (fibre) luminosity function follows well the luminosity function of inactive non-emission line galaxies (NEG), consistent with a fixed fraction of ~ 3% of NEG hosting an AGN, regardless of the host luminosity. 4. The optical-UV SED of the more luminous AGN shows a small dispersion, consistent with dust reddening of a blue SED, as expected for thermal thin accretion disc emission. 5. There is a rather tight relation of νLν(2 keV) and LbHα, which provides a useful probe for unobscured (true) type 2 AGN.

  16. CANDELS: CONSTRAINING THE AGN-MERGER CONNECTION WITH HOST MORPHOLOGIES AT z {approx} 2

    SciTech Connect

    Kocevski, Dale D.; Faber, S. M.; Mozena, Mark; Trump, Jonathan R.; Koo, David C.; Nandra, Kirpal; Brusa, Marcella; Wuyts, Stijn; Rangel, Cyprian; Laird, Elise S.; Bell, Eric F.; Alexander, David M.; Bournaud, Frederic; Conselice, Christopher J.; Dekel, Avishai; and others

    2012-01-10

    Using Hubble Space Telescope/WFC3 imaging taken as part of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey, we examine the role that major galaxy mergers play in triggering active galactic nucleus (AGN) activity at z {approx} 2. Our sample consists of 72 moderate-luminosity (L{sub X} {approx} 10{sup 42-44} erg s{sup -1}) AGNs at 1.5 < z < 2.5 that are selected using the 4 Ms Chandra observations in the Chandra Deep Field South, the deepest X-ray observations to date. Employing visual classifications, we have analyzed the rest-frame optical morphologies of the AGN host galaxies and compared them to a mass-matched control sample of 216 non-active galaxies at the same redshift. We find that most of the AGNs reside in disk galaxies (51.4{sup +5.8}{sub -5.9}%), while a smaller percentage are found in spheroids (27.8{sup +5.8}{sub -4.6}%). Roughly 16.7{sup +5.3}{sub -3.5}% of the AGN hosts have highly disturbed morphologies and appear to be involved in a major merger or interaction, while most of the hosts (55.6{sup +5.6}{sub -5.9}%) appear relatively relaxed and undisturbed. These fractions are statistically consistent with the fraction of control galaxies that show similar morphological disturbances. These results suggest that the hosts of moderate-luminosity AGNs are no more likely to be involved in an ongoing merger or interaction relative to non-active galaxies of similar mass at z {approx} 2. The high disk fraction observed among the AGN hosts also appears to be at odds with predictions that merger-driven accretion should be the dominant AGN fueling mode at z {approx} 2, even at moderate X-ray luminosities. Although we cannot rule out that minor mergers are responsible for triggering these systems, the presence of a large population of relatively undisturbed disk-like hosts suggests that the stochastic accretion of gas plays a greater role in fueling AGN activity at z {approx} 2 than previously thought.

  17. Two-stage, acetic acid-aqueous ammonia, fractionation of empty fruit bunches for increased lignocellulosic biomass utilization.

    PubMed

    Kim, Dong Young; Kim, Young Soo; Kim, Tae Hyun; Oh, Kyeong Keun

    2016-01-01

    Fractionation of EFB was conducted in two consecutive steps using a batch reaction system: hemicellulose hydrolysis using acetic acid (AA; 3.0-7.0 wt.%) at 170-190°C for 10-20 min in the first stage, and lignin solubilization using ammonium hydroxide (5-20 wt.%) at 140-220°C for 5-25 min in the second stage. The two-stage process effectively fractionated empty fruit bunches (EFB) in terms of hemicellulose hydrolysis (53.6%) and lignin removal (59.5%). After the two-stage treatment, the fractionated solid contained 65.3% glucan. Among three investigated process parameters, reaction temperature and ammonia concentration had greater impact on the delignification reaction in the second stage than reaction time. The two-stage fractionation processing improved the enzymatic digestibility to 72.9% with 15 FPU of cellulase/g of glucan supplemented with 70 pNPG of β-glycosidase (Novozyme 188)/g-glucan, which was significantly enhanced from the equivalent digestibility of 28.3% for untreated EFB and 45.7% for AAH-fractionated solid. PMID:26419963

  18. AGN Zoo and Classifications of Active Galaxies

    NASA Astrophysics Data System (ADS)

    Mickaelian, Areg M.

    2015-07-01

    We review the variety of Active Galactic Nuclei (AGN) classes (so-called "AGN zoo") and classification schemes of galaxies by activity types based on their optical emission-line spectrum, as well as other parameters and other than optical wavelength ranges. A historical overview of discoveries of various types of active galaxies is given, including Seyfert galaxies, radio galaxies, QSOs, BL Lacertae objects, Starbursts, LINERs, etc. Various kinds of AGN diagnostics are discussed. All known AGN types and subtypes are presented and described to have a homogeneous classification scheme based on the optical emission-line spectra and in many cases, also other parameters. Problems connected with accurate classifications and open questions related to AGN and their classes are discussed and summarized.

  19. ZFOURGE catalogue of AGN candidates: an enhancement of 160-μm-derived star formation rates in active galaxies to z = 3.2

    NASA Astrophysics Data System (ADS)

    Cowley, Michael J.; Spitler, Lee R.; Tran, Kim-Vy H.; Rees, Glen A.; Labbé, Ivo; Allen, Rebecca J.; Brammer, Gabriel B.; Glazebrook, Karl; Hopkins, Andrew M.; Juneau, Stéphanie; Kacprzak, Glenn G.; Mullaney, James R.; Nanayakkara, Themiya; Papovich, Casey; Quadri, Ryan F.; Straatman, Caroline M. S.; Tomczak, Adam R.; van Dokkum, Pieter G.

    2016-03-01

    We investigate active galactic nuclei (AGN) candidates within the FourStar Galaxy Evolution Survey (ZFOURGE) to determine the impact they have on star formation in their host galaxies. We first identify a population of radio, X-ray, and infrared-selected AGN by cross-matching the deep Ks-band imaging of ZFOURGE with overlapping multiwavelength data. From this, we construct a mass-complete (log(M_{{*}}/M_{{⊙}}) ≥9.75), AGN luminosity limited sample of 235 AGN hosts over z = 0.2-3.2. We compare the rest-frame U - V versus V - J (UVJ) colours and specific star formation rates (sSFRs) of the AGN hosts to a mass-matched control sample of inactive (non-AGN) galaxies. UVJ diagnostics reveal AGN tend to be hosted in a lower fraction of quiescent galaxies and a higher fraction of dusty galaxies than the control sample. Using 160 μm Herschel PACS data, we find the mean specific star formation rate of AGN hosts to be elevated by 0.34 ± 0.07 dex with respect to the control sample across all redshifts. This offset is primarily driven by infrared-selected AGN, where the mean sSFR is found to be elevated by as much as a factor of ˜5. The remaining population, comprised predominantly of X-ray AGN hosts, is found mostly consistent with inactive galaxies, exhibiting only a marginal elevation. We discuss scenarios that may explain these findings and postulate that AGN are less likely to be a dominant mechanism for moderating galaxy growth via quenching than has previously been suggested.

  20. The Evolutionary Connection Bewtween z~2-3 Submillimeter Galaxies and AGN as Probed by Molecular Gas Excitation

    NASA Astrophysics Data System (ADS)

    Sharon, Chelsea E.; Riechers, Dominik A.; Carilli, Chris Luke; Hodge, Jacqueline; Walter, Fabian

    2016-01-01

    Theoretical work has suggested that active galactic nuclei (AGN) play an important role in quenching star formation in massive galaxies. Direct evidence for AGN affecting the molecular ISM has so far been limited to detections of molecular outflows in low-redshift systems and extreme excitation regions which represent a tiny fraction of the total gas. Indirect evidence for AGN's impact on their host galaxies' cold gas phase may be provided by measurements of the gas excitation and dynamics. At z~2-3, the peak epoch of star formation and AGN activity, previous observations of the CO(1-0) line revealed that submillimeter galaxies (SMGs) have multi-phase molecular gas, including substantial reservoirs of cold-phase gas. However, the entirety of the molecular gas in AGN-host galaxies appears highly excited, potentially supporting an evolutionary connection between these two populations. I will present a new VLA sample that nearly doubles the number of CO(1-0) detections in z~2-3 SMGs and AGN-host galaxies that allows us to better compare the cold gas properties of these systems and further investigate evidence for the effects of AGN on the star-forming molecular gas.

  1. THE BULK OF THE BLACK HOLE GROWTH SINCE z {approx} 1 OCCURS IN A SECULAR UNIVERSE: NO MAJOR MERGER-AGN CONNECTION

    SciTech Connect

    Cisternas, Mauricio; Jahnke, Knud; Inskip, Katherine J.; Robaina, Aday R.; Andrae, Rene; Kartaltepe, Jeyhan; Koekemoer, Anton M.; Lisker, Thorsten; Scodeggio, Marco; Sheth, Kartik; Capak, Peter; Trump, Jonathan R.; Impey, Chris D.; Miyaji, Takamitsu; Lusso, Elisabeta; Brusa, Marcella; Cappelluti, Nico; Civano, Francesca; Ilbert, Olivier; Leauthaud, Alexie

    2011-01-10

    What is the relevance of major mergers and interactions as triggering mechanisms for active galactic nuclei (AGNs) activity? To answer this long-standing question, we analyze 140 XMM-Newton-selected AGN host galaxies and a matched control sample of 1264 inactive galaxies over z {approx} 0.3-1.0 and M{sub *} < 10{sup 11.7} M{sub sun} with high-resolution Hubble Space Telescope/Advanced Camera for Surveys imaging from the COSMOS field. The visual analysis of their morphologies by 10 independent human classifiers yields a measure of the fraction of distorted morphologies in the AGN and control samples, i.e., quantifying the signature of recent mergers which might potentially be responsible for fueling/triggering the AGN. We find that (1) the vast majority (>85%) of the AGN host galaxies do not show strong distortions and (2) there is no significant difference in the distortion fractions between active and inactive galaxies. Our findings provide the best direct evidence that, since z {approx} 1, the bulk of black hole (BH) accretion has not been triggered by major galaxy mergers, therefore arguing that the alternative mechanisms, i.e., internal secular processes and minor interactions, are the leading triggers for the episodes of major BH growth. We also exclude an alternative interpretation of our results: a substantial time lag between merging and the observability of the AGN phase could wash out the most significant merging signatures, explaining the lack of enhancement of strong distortions on the AGN hosts. We show that this alternative scenario is unlikely due to (1) recent major mergers being ruled out for the majority of sources due to the high fraction of disk-hosted AGNs, (2) the lack of a significant X-ray signal in merging inactive galaxies as a signature of a potential buried AGN, and (3) the low levels of soft X-ray obscuration for AGNs hosted by interacting galaxies, in contrast to model predictions.

  2. A New Population of Compton-thick AGNs Identified Using the Spectral Curvature above 10 keV

    NASA Astrophysics Data System (ADS)

    Koss, Michael J.; Assef, R.; Baloković, M.; Stern, D.; Gandhi, P.; Lamperti, I.; Alexander, D. M.; Ballantyne, D. R.; Bauer, F. E.; Berney, S.; Brandt, W. N.; Comastri, A.; Gehrels, N.; Harrison, F. A.; Lansbury, G.; Markwardt, C.; Ricci, C.; Rivers, E.; Schawinski, K.; Trakhtenbrot, B.; Treister, E.; Urry, C. Megan

    2016-07-01

    We present a new metric that uses the spectral curvature (SC) above 10 keV to identify Compton-thick active galactic nuclei (AGNs) in low-quality Swift/Burst Alert Telescope (BAT) X-ray data. Using NuSTAR, we observe nine high SC-selected AGNs. We find that high-sensitivity spectra show that the majority are Compton-thick (78% or 7/9) and the remaining two are nearly Compton-thick (N H ≃ (5–8) × 1023 cm‑2 ). We find that the SC BAT and SC NuSTAR measurements are consistent, suggesting that this technique can be applied to future telescopes. We tested the SC method on well-known Compton-thick AGNs and found that it is much more effective than broadband ratios (e.g., 100% using SC versus 20% using 8–24 keV/3–8 keV). Our results suggest that using the >10 keV emission may be the only way to identify this population since only two sources show Compton-thick levels of excess in the Balmer decrement corrected [O iii] to observed X-ray emission ratio ({F}[{{O}{{III}}]}/{F}2{--10 {keV}}{obs}\\gt 1) and WISE colors do not identify most of them as AGNs. Based on this small sample, we find that a higher fraction of these AGNs are in the final merger stage (<10 kpc) than typical BAT AGNs. Additionally, these nine obscured AGNs have, on average, ≈4× higher accretion rates than other BAT-detected AGNs (< {λ }{Edd}> \\=\\0.068+/- 0.023 compared to < {λ }{Edd}> \\=\\0.016+/- 0.004). The robustness of SC at identifying Compton-thick AGNs implies that a higher fraction of nearby AGNs may be Compton-thick (≈22%) and the sum of black hole growth in Compton-thick AGNs (Eddington ratio times population percentage) is nearly as large as mildly obscured and unobscured AGNs.

  3. Plants increase arsenic in solution but decrease the non-specifically bound fraction in the rhizosphere of an alkaline, naturally rich soil.

    PubMed

    Obeidy, Carole; Bravin, Matthieu N; Bouchardon, Jean-Luc; Conord, Cyrille; Moutte, Jacques; Guy, Bernard; Faure, Olivier

    2016-04-01

    We aimed at determining the major physical-chemical processes that drive arsenic (As) dynamic in the rhizosphere of four species (Holcus lanatus, Dittrichia viscosa, Lotus corniculatus, Plantago lanceolata) tested for phytostabilization. Experiments were performed with an alkaline soil naturally rich in As. Composition of the soil solution of planted and unplanted pots was monitored every 15 days for 90 days, with a focus on the evolution of As concentrations in solution and in the non-specifically bound (i.e. easily exchangeable) fraction. The four species similarly increased As concentration in solution, but decreased As concentration in the non-specifically bound fraction. The major part (60%) of As desorbed from the non-specifically bound fraction in planted pots was likely redistributed on the less available fractions of As on the solid phase. A second part (35%) of desorbed As was taken up by plants. The minor part (5%) of desorbed As supplied As increase in solution. To conclude, plants induced a substantial redistribution of As on the less available fractions in the rhizosphere, as expected in phytostabilization strategies. Plants however concomitantly increased As concentration in the rhizosphere solution which may contribute to As transfer through plant uptake and leaching. PMID:26707185

  4. Compton Thick AGN in the COSMOS field

    NASA Astrophysics Data System (ADS)

    Lanzuisi, Giorgio; Cosmos Collaboration

    2015-09-01

    I will present the results we published in a couple of recent papers (Lanzuisi et al. 2015, A&A 573A 137, Lanzuisi et al. 2015, arXiv 1505.01153) on the properties of X-ray selected Compton Thick (CT, NH>10^24 cm^-2) AGN, in the COSMOS survey. We exploited the rich multi-wavelength dataset available in this field, to show that CT AGN tend to harbor smaller, rapidly growing SMBH with respect to unobscured AGN, and have a higher chance of being hosted by star-forming, merging and post-merger systems.We also demonstrated the detectability of even more heavily obscured AGN (NH>10^25 cm^-2), thanks to a truly multi-wavelength approach in the same field. The extreme source detected in this way shows strong evidences of ongoing powerful AGN feedback, detected as blue-shifted wings of high ionization optical emission lines such as [NeV] and [FeVII], as well as of the [OIII] emission line.The results obtained from these works point toward a scenario in which highly obscured AGN occupy a peculiar place in the galaxy-AGN co-evolution process, in which both the host and the SMBH rapidly evolve toward the local relations.We will also present estimates on the detectability of such extreme sources up to redshift ~6-7 with Athena. Combining the most up to date models for the Luminosity Function of CT AGN at high z, aggressive data analysis techniques on faint sources, and the current Athena survey design, we demonstrate that we will detect, and recognize as such, a small (few to ten) but incredibly valuable sample of CT AGN at such high redshift.

  5. Radio galaxies in ZFOURGE/NMBS: no difference in the properties of massive galaxies with and without radio-AGN out to z = 2.25

    NASA Astrophysics Data System (ADS)

    Rees, G. A.; Spitler, L. R.; Norris, R. P.; Cowley, M. J.; Papovich, C.; Glazebrook, K.; Quadri, R. F.; Straatman, C. M. S.; Allen, R.; Kacprzak, G. G.; Labbe, I.; Nanayakkara, T.; Tomczak, A. R.; Tran, K.-V.

    2016-01-01

    In order to reproduce the high-mass end of the galaxy mass distribution, some process must be responsible for the suppression of star formation in the most massive of galaxies. Commonly active galactic nuclei (AGN) are invoked to fulfil this role, but the exact means by which they do so is still the topic of much debate, with studies finding evidence for both the suppression and enhancement of star formation in AGN hosts. Using the ZFOURGE (FourStar Galaxy Evolution) and NMBS (Newfirm Medium Band Survey) galaxy surveys, we investigate the host galaxy properties of a mass-limited (M ≥ 1010.5 M⊙), high-luminosity (L1.4 > 1024 W Hz-1) sample of radio-loud AGN to a redshift of z = 2.25. In contrast to low-redshift studies, which associate radio-AGN activity with quiescent hosts, we find that the majority of z > 1.5 radio-AGN are hosted by star-forming galaxies. Indeed, the stellar populations of radio-AGN are found to evolve with redshift in a manner that is consistent with the non-AGN mass-similar galaxy population. Interestingly, we find that the radio-AGN fraction is constant across a redshift range of 0.25 ≤ z < 2.25, perhaps indicating that the radio-AGN duty cycle has little dependence on redshift or galaxy type. We do however see a strong relation between the radio-AGN fraction and stellar mass, with radio-AGN becoming rare below ˜1010.5 M⊙ or a halo mass of 1012 M⊙. This halo-mass threshold is in good agreement with simulations that initiate radio-AGN feedback at this mass limit. Despite this, we find that radio-AGN host star formation rates are consistent with the non-AGN mass-similar galaxy sample, suggesting that while radio-AGN are in the right place to suppress star formation in massive galaxies they are not necessarily responsible for doing so.

  6. Hydrodynamic models of AGN feedback in cooling core clusters

    NASA Astrophysics Data System (ADS)

    Vernaleo, John C.

    X-ray observations show that the Intra Cluster Medium (ICM) in many galaxy clusters is cooling at a rapid rate, often to the point that it should have radiated away all of its energy in less than the age of the cluster. There is however a very clear lack of enough cool end products of this gas in the centers of the clusters. Energetic arguments indicate that Active Galactic Nuclei (AGN) should be capable of heating the inner regions of clusters enough to offset the radiative cooling; truncating massive galaxy formation and solving the cooling flow problem. We present three sets of high resolution, ideal hydrodynamic simulations with the ZEUS code to test this AGN heating paradigm. For the first set of simulations, we study the dependence of the interaction between the AGN jets and the ICM on the parameters of the jets themselves. We present a parameter survey of two-dimensional (axisymmetric) models of back-to-back jets injected into a cluster atmosphere. We follow the passive evolution of the resulting structures. These simulations fall into roughly two classes, cocoon-bounded and non-cocoon bounded. We find that the cocoon-bounded sources inject significantly more entropy into the core regions of the ICM atmosphere, even though the efficiency with which the energy is thermalized is independent of the morphological class. In all cases, a large fraction of the energy injected by the jet ends up as gravitational potential energy due to the expansion of the atmosphere. For the second set, we present three-dimensional simulations of jetted AGN that act in response to cooling-mediated accretion of an ICM atmosphere. We find that our models are incapable of producing a long term balance of heating and cooling; catastrophic cooling can be delayed by the jet action but inevitably takes hold. At the heart of the failure of these models is the formation of a low density channel through which the jet can freely flow, carrying its energy out of the cooling core. Finally, we

  7. Cooling, AGN Feedback, and Star Formation in Simulated Cool-core Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Li, Yuan; Bryan, Greg L.; Ruszkowski, Mateusz; Voit, G. Mark; O'Shea, Brian W.; Donahue, Megan

    2015-10-01

    Numerical simulations of active galactic nuclei (AGNs) feedback in cool-core galaxy clusters have successfully avoided classical cooling flows, but often produce too much cold gas. We perform adaptive mesh simulations that include momentum-driven AGN feedback, self-gravity, star formation, and stellar feedback, focusing on the interplay between cooling, AGN heating, and star formation in an isolated cool-core cluster. Cold clumps triggered by AGN jets and turbulence form filamentary structures tens of kpc long. This cold gas feeds both star formation and the supermassive black hole (SMBH), triggering an AGN outburst that increases the entropy of the intracluster medium (ICM) and reduces its cooling rate. Within 1-2 Gyr, star formation completely consumes the cold gas, leading to a brief shutoff of the AGN. The ICM quickly cools and redevelops multiphase gas, followed by another cycle of star formation/AGN outburst. Within 6.5 Gyr, we observe three such cycles. There is good agreement between our simulated cluster and the observations of cool-core clusters. ICM cooling is dynamically balanced by AGN heating, and a cool-core appearance is preserved. The minimum cooling time to free-fall time ratio typically varies between a few and ≳ 20. The star formation rate (SFR) covers a wide range, from 0 to a few hundred {M}⊙ {{yr}}-1, with an average of ˜ 40 {M}⊙ {{yr}}-1. The instantaneous SMBH accretion rate shows large variations on short timescales, but the average value correlates well with the SFR. Simulations without stellar feedback or self-gravity produce qualitatively similar results, but a lower SMBH feedback efficiency (0.1% compared to 1%) results in too many stars.

  8. A statistical study of H i gas in nearby narrow-line AGN-hosting galaxies

    SciTech Connect

    Zhu, Yi-Nan; Wu, Hong E-mail: hwu@bao.ac.cn

    2015-01-01

    As a quenching mechanism, active galactic nucleus (AGN) feedback could suppress on going star formation in host galaxies. On the basis of a sample of galaxies selected from the Arecibo Legacy Fast ALFA (ALFALFA) H i survey, the dependence of the H i mass (M{sub H} {sub i}), stellar mass (M{sub *}), and H i-to-stellar mass ratio (M{sub H} {sub i}/M{sub *}) on various tracers of AGN activity are presented and analyzed in this paper. Almost all the AGN hostings in this sample are gas-rich galaxies, and there is not any evidence to indicate that the AGN activity could increase or decrease either M{sub H} {sub i} or M{sub H} {sub i}/M{sub *}. The position of the cold neutral gas cannot be fixed accurately based only on available H i data, due to the large beam size of ALFALFA survey. In addition, even though AGN hostings are more easily detected by an H i survey compared with absorption line galaxies, these two types of galaxies show similar star formation history. If an AGN hosting would ultimately evolve into an old red galaxy with low cold gas, then when and how the gas has been exhausted must be solved by future hypotheses and observations.

  9. ISO Key Project: Exploring the Full Range of Quasar/AGN Properties

    NASA Technical Reports Server (NTRS)

    Wilkes, B.

    2001-01-01

    The origin of the infrared emission in Active Galactic Nuclei (AGN), whose strength is comparable to the optical/ultra-violet (OUV) emission, is generally thought to be a combination of thermal emission from dust and non-thermal, synchrotron emission. Although data are sparse, particularly in the far-infrared, the broad wavelength range of this emission suggests a wide range of temperatures and a combination of AGN and starburst heating mechanisms. The strength of the non-thermal emission is expected to be related to the radio emission. While this scenario is well-established, basic questions, such as the spatial and temperature distribution of the dust, the relative importance of AGN and starburst heating, and the significance of the non-thermal contribution, remain largely undetermined. The wide wavelength range of the Infrared Space Observatory (ISO) combined with its arcmin spatial resolution and increased sensitivity facilitated the observation of a larger subset of the AGN population than previously covered, allowing these questions to be investigated in more detail. This paper will review the spectral energy distributions (SED) of AGN with particular emphasis on the infrared emission and on ISO contributions to our knowledge. Preliminary results from ISO observations of X-ray selected and high-redshift AGN will be described.

  10. The dark matter haloes of moderate luminosity X-ray AGN as determined from weak gravitational lensing and host stellar masses

    NASA Astrophysics Data System (ADS)

    Leauthaud, Alexie; J. Benson, Andrew; Civano, Francesca; L. Coil, Alison; Bundy, Kevin; Massey, Richard; Schramm, Malte; Schulze, Andreas; Capak, Peter; Elvis, Martin; Kulier, Andrea; Rhodes, Jason

    2015-01-01

    Understanding the relationship between galaxies hosting active galactic nuclei (AGN) and the dark matter haloes in which they reside is key to constraining how black hole fuelling is triggered and regulated. Previous efforts have relied on simple halo mass estimates inferred from clustering, weak gravitational lensing, or halo occupation distribution modelling. In practice, these approaches remain uncertain because AGN, no matter how they are identified, potentially live a wide range of halo masses with an occupation function whose general shape and normalization are poorly known. In this work, we show that better constraints can be achieved through a rigorous comparison of the clustering, lensing, and cross-correlation signals of AGN hosts to the fiducial stellar-to-halo mass relation (SHMR) derived for all galaxies, irrespective of nuclear activity. Our technique exploits the fact that the global SHMR can be measured with much higher accuracy than any statistic derived from AGN samples alone. Using 382 moderate luminosity X-ray AGN at z < 1 from the COSMOS field, we report the first measurements of weak gravitational lensing from an X-ray-selected sample. Comparing this signal to predictions from the global SHMR, we find that, contrary to previous results, most X-ray AGN do not live in medium size groups - nearly half reside in relatively low mass haloes with M200b ˜ 1012.5 M⊙. The AGN occupation function is well described by the same form derived for all galaxies but with a lower normalization - the fraction of haloes with AGN in our sample is a few per cent. The number of AGN satellite galaxies scales as a power law with host halo mass with a power-law index α = 1. By highlighting the relatively `normal' way in which moderate luminosity X-ray AGN hosts occupy haloes, our results suggest that the environmental signature of distinct fuelling modes for luminous quasars compared to moderate luminosity X-ray AGN is less obvious than previously claimed.

  11. Effects of AGN feedback on ΛCDM galaxies

    NASA Astrophysics Data System (ADS)

    Lagos, Claudia Del P.; Cora, Sofía A.; Padilla, Nelson D.

    2008-08-01

    We study the effects of active galactic nuclei (AGN) feedback on the formation and evolution of galaxies by using a combination of a cosmological N-body simulation of the concordance Lambda cold dark matter (ΛCDM) paradigm and a semi-analytic model of galaxy formation. This model is an improved version of the one described by Cora (2006), which now considers the growth of black holes (BHs) as driven by (i) gas accretion during merger-driven starbursts and mergers with other BHs, (ii) accretion during starbursts triggered by disc instabilities and (iii) accretion of gas cooled from quasi-hydrostatic hot gas haloes. It is assumed that feedback from AGN operates in the last case. The model has been calibrated in order to reproduce observational correlations between BH mass and mass, velocity dispersion and absolute magnitudes of the galaxy bulge. AGN feedback has a strong impact on reducing or even suppressing gas cooling, an effect that becomes important at lower redshifts. This phenomenon helps to reproduce the observed galaxy luminosity function (LF) in the optical and near-infrared bands at z = 0, and the cosmic star formation rate and stellar mass functions over a wide redshift range (0 <~ z <~ 5). It also allows us to have a population of massive galaxies already in place at z >~ 1, which are mostly early-type and have older and redder stellar populations than lower mass galaxies, reproducing the observed bimodality in the galaxy colour distribution, and the morphological fractions. The evolution of the optical QSO LF is also reproduced, provided that the presence of a significant fraction of obscured QSOs is assumed. We explore the effects of AGN feedback during starbursts finding that, in order to obtain a good agreement with observations, these need to be strong enough to expel the reheated gas away from the galaxy halo. We also test new, recent prescriptions for dynamical friction time-scales, and find that they produce an earlier formation of elliptical

  12. Modeling AGN outbursts from supermassive black hole binaries

    NASA Astrophysics Data System (ADS)

    Tanaka, T.

    2012-12-01

    When galaxies merge to assemble more massive galaxies, their nuclear supermassive black holes (SMBHs) should form bound binaries. As these interact with their stellar and gaseous environments, they will become increasingly compact, culminating in inspiral and coalescence through the emission of gravitational radiation. Because galaxy mergers and interactions are also thought to fuel star formation and nuclear black hole activity, it is plausible that such binaries would lie in gas-rich environments and power active galactic nuclei (AGN). The primary difference is that these binaries have gravitational potentials that vary - through their orbital motion as well as their orbital evolution - on humanly tractable timescales, and are thus excellent candidates to give rise to coherent AGN variability in the form of outbursts and recurrent transients. Although such electromagnetic signatures would be ideally observed concomitantly with the binary's gravitational-wave signatures, they are also likely to be discovered serendipitously in wide-field, high-cadence surveys; some may even be confused for stellar tidal disruption events. I discuss several types of possible "smoking gun" AGN signatures caused by the peculiar geometry predicted for accretion disks around SMBH binaries.

  13. Delving into X-ray obscuration of type 2 AGN, near and far

    SciTech Connect

    LaMassa, Stephanie M.; Meg Urry, C.; Yaqoob, Tahir; Ptak, Andrew F.; Gandhi, Poshak

    2014-05-20

    Using self-consistent, physically motivated models, we investigate the X-ray obscuration in 19 Type 2 [O III] 5007 Å selected active galactic nuclei (AGNs), 9 of which are local Seyfert 2 galaxies and 10 of which are Type 2 quasar candidates. We derive reliable line-of-sight and global column densities for these objects, which is the first time this has been reported for an AGN sample; four AGNs have significantly different global and line-of-sight column densities. Five sources are heavily obscured to Compton-thick. We comment on interesting sources revealed by our spectral modeling, including a candidate 'naked' Sy2. After correcting for absorption, we find that the ratio of the rest-frame, 2-10 keV luminosity (L{sub 2-10} {sub keV,} {sub in}) to L{sub [O} {sub III]} is 1.54 ± 0.49 dex which is essentially identical to the mean Type 1 AGN value. The Fe Kα luminosity is significantly correlated with L{sub [O} {sub III]} but with substantial scatter. Finally, we do not find a trend between L {sub 2-10keV,} {sub in} and global or line-of-sight column density, between column density and redshift, between column density and scattering fraction, or between scattering fraction and redshift.

  14. Delving into X-Ray Obscuration of Type 2 AGN, Near and Far

    NASA Technical Reports Server (NTRS)

    Lamassa, Stephanie M.; Yaqoob, Tahir; Ptak, Andrew F.; Jia, Jianjun; Heckman, Timothy M.; Gandhi, Poshak; Urry, C. Meg

    2014-01-01

    Using self-consistent, physically motivated models, we investigate the X-ray obscuration in 19 Type 2 [O iii] 5007Å selected active galactic nuclei (AGNs), 9 of which are local Seyfert 2 galaxies and 10 of which are Type 2 quasar candidates. We derive reliable line-of-sight and global column densities for these objects, which is the first time this has been reported for an AGN sample; four AGNs have significantly different global and line-of-sight column densities. Five sources are heavily obscured to Compton-thick. We comment on interesting sources revealed by our spectral modeling, including a candidate "naked" Sy2. After correcting for absorption, we find that the ratio of the rest-frame, 2-10 keV luminosity (L2-10 keV,in) to L[O iii] is 1.54 +/- 0.49 dex which is essentially identical to the mean Type 1 AGN value. The Fe K(alpha) luminosity is significantly correlated with L[O iii] but with substantial scatter. Finally, we do not find a trend between L2-10 keV,in and global or line-of-sight column density, between column density and redshift, between column density and scattering fraction, or between scattering fraction and redshift. Key words: galaxies: active - galaxies: Seyfert - X-rays: general

  15. They Call Me Agnes: A Crow Narrative Based on the Life of Agnes Yellowtail Deernose.

    ERIC Educational Resources Information Center

    Voget, Fred W.; Mee, Mary K.

    This book is about life on the Crow Indian Reservation from around 1910 to the present and is based on the personal experiences of Donnie and Agnes Deernose. Following Donnie's death, Agnes became the principal narrator of the book. The Crow Indian Reservation is situated between Billings, Montana, and Sheridan, Wyoming. More so than any other…

  16. Bright and Faint Ends of Lyα Luminosity Functions at z = 2 Determined by the Subaru Survey: Implications for AGNs, Magnification Bias, and ISM H I Evolution

    NASA Astrophysics Data System (ADS)

    Konno, Akira; Ouchi, Masami; Nakajima, Kimihiko; Duval, Florent; Kusakabe, Haruka; Ono, Yoshiaki; Shimasaku, Kazuhiro

    2016-05-01

    We present the Lyα luminosity functions (LFs) derived by our deep Subaru narrowband survey that identifies a total of 3137 Lyα emitters (LAEs) at z = 2.2 in five independent blank fields. This sample of LAEs is the largest to date and covers a very wide Lyα luminosity range of {log}{L}{Lyα }=41.7{--}44.4 erg s‑1. We determine the Lyα LF at z = 2.2 with unprecedented accuracy and obtain the best-fit Schechter parameters of {L}{Lyα }*={5.29}-1.13+1.67× {10}42 erg s‑1, {φ }{Lyα }*={6.32}-2.31+3.08× {10}-4 Mpc‑3, and α =-{1.75}-0.09+0.10, showing a steep faint-end slope. We identify a significant hump at the LF bright end ({log}{L}{Lyα }\\gt 43.4 erg s‑1). Because all of the LAEs in the bright-end hump have a bright counterpart(s) in either the X-ray, UV, or radio data, this bright-end hump is not made by gravitational lensing magnification bias but by active galactic nuclei (AGNs). These AGNs allow us to derive the AGN UV LF at z ∼ 2 down to the faint magnitude limit of M UV ≃ ‑22.5 and to constrain the faint-end slope of the AGN UV LF, α AGN = ‑1.2 ± 0.1, which is flatter than those at z > 4. Based on the Lyα and UV LFs from our and previous studies, we find an increase of Lyα escape fraction {f}{esc}{Lyα } from z ∼ 0 to 6 by two orders of magnitude. This large {f}{esc}{Lyα } increase can be explained neither by the evolution of stellar population nor by outflow alone, but by the evolution of neutral hydrogen H i density in the interstellar medium that enhances dust attenuation for Lyα by resonance scattering. Our uniform expanding shell models suggest that the typical H i column density decreases from {N}{{H}{{I}}}∼ 7× {10}19 (z ∼ 0) to ∼1 × 1018 cm‑2 (z ∼ 6) to explain the large {f}{esc}{Lyα } increase.

  17. Bright and Faint Ends of Lyα Luminosity Functions at z = 2 Determined by the Subaru Survey: Implications for AGNs, Magnification Bias, and ISM H I Evolution

    NASA Astrophysics Data System (ADS)

    Konno, Akira; Ouchi, Masami; Nakajima, Kimihiko; Duval, Florent; Kusakabe, Haruka; Ono, Yoshiaki; Shimasaku, Kazuhiro

    2016-05-01

    We present the Lyα luminosity functions (LFs) derived by our deep Subaru narrowband survey that identifies a total of 3137 Lyα emitters (LAEs) at z = 2.2 in five independent blank fields. This sample of LAEs is the largest to date and covers a very wide Lyα luminosity range of {log}{L}{Lyα }=41.7{--}44.4 erg s‑1. We determine the Lyα LF at z = 2.2 with unprecedented accuracy and obtain the best-fit Schechter parameters of {L}{Lyα }*={5.29}-1.13+1.67× {10}42 erg s‑1, {φ }{Lyα }*={6.32}-2.31+3.08× {10}-4 Mpc‑3, and α =-{1.75}-0.09+0.10, showing a steep faint-end slope. We identify a significant hump at the LF bright end ({log}{L}{Lyα }\\gt 43.4 erg s‑1). Because all of the LAEs in the bright-end hump have a bright counterpart(s) in either the X-ray, UV, or radio data, this bright-end hump is not made by gravitational lensing magnification bias but by active galactic nuclei (AGNs). These AGNs allow us to derive the AGN UV LF at z ˜ 2 down to the faint magnitude limit of M UV ≃ ‑22.5 and to constrain the faint-end slope of the AGN UV LF, α AGN = ‑1.2 ± 0.1, which is flatter than those at z > 4. Based on the Lyα and UV LFs from our and previous studies, we find an increase of Lyα escape fraction {f}{esc}{Lyα } from z ˜ 0 to 6 by two orders of magnitude. This large {f}{esc}{Lyα } increase can be explained neither by the evolution of stellar population nor by outflow alone, but by the evolution of neutral hydrogen H i density in the interstellar medium that enhances dust attenuation for Lyα by resonance scattering. Our uniform expanding shell models suggest that the typical H i column density decreases from {N}{{H}{{I}}}˜ 7× {10}19 (z ˜ 0) to ˜1 × 1018 cm‑2 (z ˜ 6) to explain the large {f}{esc}{Lyα } increase.

  18. Dependence of the broad Fe Kα line on the physical parameters of AGN

    NASA Astrophysics Data System (ADS)

    Liu, Zhu; Yuan, Weimin; Lu, Youjun; Carrera, Francisco J.; Falocco, Serena; Dong, Xiao-Bo

    2016-08-01

    In this paper, the dependence of the broad Fe Kα line on the physical parameters of AGN, such as the black hole mass MBH, accretion rate (equivalently represented by Eddington ratio λEdd), and optical classification, is investigated by applying the X-ray spectra stacking method to a large sample of AGN which have well measured optical parameters. A broad line feature is detected (>3σ) in the stacked spectra of the high λEdd sub-sample (log λEdd > -0.9). The profile of the broad line can be well fitted with relativistic broad line model, with the line energy consistent with highly ionized Fe Kα line (i.e. Fe XXVI). A model consisting of multiple narrow lines cannot be ruled out, however. We found hints that the Fe K line becomes broader as the λEdd increases. No broad line feature is shown in the sub-sample of broad-line Seyfert 1 (BLS1) galaxies and in the full sample, while a broad line might be present, though at low significance, in the sub-sample of narrow-line Seyfert 1 (NLS1) galaxies. We find no strong dependence of the broad line on black hole masses. Our results indicate that the detection/properties of the broad Fe Kα line may strongly depend on λEdd, which can be explained if the ionization state and/or truncation radius of the accretion disc changes with λEdd. The non-detection of the broad line in the BLS1 sub-sample can be explained if the the average EW of the relativistic Fe Kα line is weak or/and the fraction of sources with relativistic Fe Kα line is small in BLS1 galaxies.

  19. The view of AGN-host alignment via reflection spectroscopy

    NASA Astrophysics Data System (ADS)

    Middleton, Matthew J.; Parker, Michael L.; Reynolds, Christopher S.; Fabian, Andrew C.; Lohfink, Anne M.

    2016-04-01

    The fuelling of active galactic nuclei (AGN) - via material propagated through the galactic disc or via minor mergers - is expected to leave an imprint on the alignment of the sub-pc disc relative to the host galaxy's stellar disc. Determining the inclination of the inner disc usually relies on the launching angle of the jet; here instead we use the inclination derived from reflection fits to a sample of AGN. We determine the distorting effect of unmodelled Fe XXV/XXVI features and, via extensive simulations, determine the difference in disc inclination resulting from the use of RELXILL compared to REFLIONX. We compare inner disc inclinations to those for the host galaxy stellar disc derived from the Hubble formula and, via Monte Carlo simulations, find a strong lack of a correlation (at ≫5σ) implying either widespread feeding via mergers if we assume the sample to be homogeneous, or that radiative disc warps are distorting our view of the emission. However, we find that by removing a small (˜1/5) subset of AGN, the remaining sample is consistent with random sampling of an underlying 1:1 correlation (at the 3σ level). A heterogenous sample would likely imply that our view is not dominated by radiative disc warps but instead by different feeding mechanisms with the majority consistent with coplanar accretion (although this may be the result of selection bias), whilst a smaller but not insignificant fraction may have been fuelled by minor mergers in the recent history of the host galaxy.

  20. Towards a paleo-salinity proxy: Decreasing D/H fractionation in algal and bacterial lipids with increasing salinity in Christmas Island saline ponds

    NASA Astrophysics Data System (ADS)

    Sachse, D.; Sachs, J. P.

    2007-12-01

    We investigated the effect of a wide range of salinities (13 -149 PSU) on the D/H ratio of lipids in microbial mat sediments from hypersaline ponds on Christmas Island. The hydrogen isotope ratios (expressed as δD values) of total lipid extracts, and the individual hydrocarbons heptadecane, heptadecene, octadecane, octadecene, diploptene and phytene from algae and bacteria, became increasingly enriched in deuterium as salinity increased, spanning a range of 100‰ while lake water δD values spanned a range of just 12‰. D/H fractionation between lipids and source water thus decreased as salinity increased. Isotope fractionation factors (αlipid-water) were strongly correlated with salinity and increased in all compound classes studied. The apparent isotope fractionation (ɛlipid-water) decreased by 0.8 to 1.1‰ per PSU increase in salinity. Differences in the hydrogen isotopic composition of lipids derived from three biosynthetic pathways (acetogenic, MVA and DOXP/MEP) remained similar irrespective of the salinity, suggesting that the mechanism responsible for the observed αlipid-water - salinity relationship originates prior to the last common biosynthetic branching point, the Calvin Cycle. These findings imply that caution must be exercised when attempting to reconstruct source water δD values using lipid δD values from aquatic environments that may have experienced salinity variations of ~3 PSU or more (based on a 1‰ per PSU response of D/H fractionation to salinity changes, and a lipid δD measurement precision of 3‰). On the other hand our results can be used to establish a paleo-salinity proxy based on algal and bacterial lipid δD values if salinity variations exceeded ~3 PSU and/or if additional constraints on source water δD values can be made.

  1. Calibrating AGN Feedback in Clusters

    NASA Astrophysics Data System (ADS)

    Wise, M. W.

    2009-12-01

    Whether caused by AGN jets, shocks, or mergers, the most definitive evidence for heating in cluster cores comes from X-ray spectroscopy. Unfortunately such spectra are essentially limited to studying the emission spectrum from the cluster as a whole. However since the same underlying emission measure distribution produces both the observed CCD and RGS spectra, X-ray imaging can still provide spatial information on the heating process. Using Chandra archival data for a sample of 9 clusters, we demonstrate how imaging data can be used to constrain departures from a canonical, isobaric cooling flow model as a function of position in a given cluster. The results of this analysis are also shown for the deep archival exposure of the Perseus cluster. Such ``heating maps'' can provide constraints on both the location and magnitude of the heating in the cores of clusters. When combined with detections and spectral index maps from low-frequency radio observations, these maps can be used to distinguish between different models for heating in these objects.

  2. The high angular resolution view of local X-ray selected AGN in the mid-infrared

    NASA Astrophysics Data System (ADS)

    Gandhi, Poshak; Asmus, D.; Hönig, S. F.; Smette, A.; Duschl, W. J.; Matsuta, K.; Ichikawa, K.; Ueda, Y.; Terashima, Y.; Gilli, R.; Comastri, A.; Vignali, C.

    2012-09-01

    Hard X-ray and mid-infrared observations probe the peaks in broadband spectra of active galactic nucle (AGN), sampling the bulk of their accretion energy. But bolometric emission measurements of Seyfert galaxies can be strongly biased by unresolved nuclear stellar emission. Disentangling these components using emission line proxies for the intrinsic AGN power suffers from various uncertainties. Here, we show that fundamental new insights into AGN are enabled by using high angular resolution observations of Seyferts with the largest telescopes currently available. We have imaged the 9 month Swift/BAT selected AGN sample using the VLT, Gemini and Subaru at their diffraction-limit at 12°. Collecting all high angular resolution data yields a large database of 150 AGN of all types with a point-like detected nucleus. This sample serves as a benchmark for studies on unification issues and accurate (unbiased) AGN bolometric corrections. We discuss some key results, including new inferences on the structures of Seyfert nuclei from the enlarged infrared/Xray correlation and show that the MIR to X-ray flux ratio is independent of the Eddington fraction (lEdd) over about 4 orders of magnitude down to lEdd 10^{-4} at least, which appears to be the threshold below which accretion properties change.

  3. X-Ray Absorbed, Broad-Lined, Red AGN and the Cosmic X-Ray Background

    NASA Technical Reports Server (NTRS)

    Mushotzky, Richard (Technical Monitor); Wilkes, Belinda

    2005-01-01

    We have obtained XMM spectra for five red, 2MASS AGN, selected from a sample observed by Chandra to be X-ray bright and to cover a range of hardness ratios. Our results confirm the presence of substantial absorbing material in three sources which have optical classifications ranging from Type 1 to Type 2, with an intrinsically flat (hard) power law continuum indicated in the other two. The presence of both X-ray absorption and broad optical emission lines with the usual strength suggests either a small (nuclear) absorber or a favored viewing angle so as to cover the X-ray source but not the broad emission line region (BELR). A soft excess is detected in all three Type 1 sources. We speculate that this soft X-ray emission may arise in an extended region of ionized gas, perhaps linked with the polarized (scattered) light which is a feature of these sources. The spectral complexity revealed by XMM emphasizes the limitations of the low S/N Chandra data. Overall, the new XMM results strengthen our conclusions (Wilkes et al. 2002) that the observed X-ray continua of red AGN are unusually hard at energies greater than 2 keV. Whether due to substantial line-of-sight absorption or to an intrinsically hard or reflection-dominated spectrum, these 'red' AGN have an observed spectral form consistent with contributing significantly to the missing had absorbed population of the Cosmic X-ray Background (CXRB). When absorption and or reflection is taken into account, all these AGN have power law slopes typical of broad-line (Type 1) AGN (Gamma approximately 1.9). This appears to resolve the spectral paradox which for so long has existed between the CXRB and the AGN thought to be the dominant contributors. It also suggests two scenarios whereby Type 1 AGN/QSOs may be responsible for a significant fraction of the CXRB at energies above 2 keV: 1) X-ray absorbed AGN/QSOs with visible broad emission lines; 2) AGN/QSOs with complex spectra whose hardness greater than 2 keV is not

  4. FRESH ACTIVITY IN OLD SYSTEMS: RADIO AGNs IN FOSSIL GROUPS OF GALAXIES

    SciTech Connect

    Hess, Kelley M.; Wilcots, Eric M.; Hartwick, Victoria L. E-mail: ewilcots@astro.wisc.edu

    2012-08-15

    We present the first systematic 1.4 GHz Very Large Array radio continuum survey of fossil galaxy group candidates. These are virialized systems believed to have assembled over a gigayear in the past through the merging of galaxy group members into a single, isolated, massive elliptical galaxy and featuring an extended hot X-ray halo. We use new photometric and spectroscopic data from Sloan Digital Sky Survey Data Release 7 to determine that three of the candidates are clearly not fossil groups. Of the remaining 30 candidates, 67% contain a radio-loud (L{sub 1.4GHz} > 10{sup 23} W Hz{sup -1}) active galactic nucleus (AGN) at the center of their dominant elliptical galaxy. We find a weak correlation between the radio luminosity of the AGN and the X-ray luminosity of the halo suggesting that the AGN contributes to energy deposition into the intragroup medium. We only find a correlation between the radio and optical luminosity of the central elliptical galaxy when we include X-ray-selected, elliptically dominated non-fossil groups, indicating a weak relationship between AGN strength and the mass assembly history of the groups. The dominant elliptical galaxy of fossil groups is on average roughly an order of magnitude more luminous than normal group elliptical galaxies in optical, X-ray, and radio luminosities and our findings are consistent with previous results that the radio-loud fraction in elliptical galaxies is linked to the stellar mass of a population. The current level of activity in fossil groups suggests that AGN fueling continues long after the last major merger. We discuss several possibilities for fueling the AGN at the present epoch.

  5. The Role of Star Formation and an AGN in Dust Heating of z = 0.3-2.8 Galaxies. I. Evolution with Redshift and Luminosity

    NASA Astrophysics Data System (ADS)

    Kirkpatrick, Allison; Pope, Alexandra; Sajina, Anna; Roebuck, Eric; Yan, Lin; Armus, Lee; Díaz-Santos, Tanio; Stierwalt, Sabrina

    2015-11-01

    We characterize infrared spectral energy distributions of 343 (ultra)luminous infrared galaxies from z = 0.3-2.8. We diagnose the presence of an active galactic nucleus (AGN) by decomposing individual Spitzer mid-IR spectroscopy into emission from star formation and an AGN-powered continuum; we classify sources as star-forming galaxies (SFGs), AGNs, or composites. Composites comprise 30% of our sample and are prevalent at faint and bright S24, making them an important source of IR AGN emission. We combine spectroscopy with multiwavelength photometry, including Herschel imaging, to create three libraries of publicly available templates (2-1000 μm). We fit the far-IR emission using a two-temperature modified blackbody to measure cold and warm dust temperatures (Tc and Tw). We find that Tc does not depend on mid-IR classification, while Tw shows a notable increase as the AGN grows more luminous. We measure a quadratic relationship between mid-IR AGN emission and total AGN contribution to LIR. AGNs, composites, and SFGs separate in S8/S3.6 and S250/S24, providing a useful diagnostic for estimating relative amounts of these sources. We estimate that >40% of IR-selected samples host an AGN, even at faint selection thresholds (S24 > 100 μJy). Our decomposition technique and color diagnostics are relevant given upcoming observations with the James Webb Space Telescope.

  6. Reconfinement shocks in relativistic AGN jets

    SciTech Connect

    Nalewajko, Krzysztof; Sikora, Marek

    2008-12-24

    Stationary knots observed in many AGN jets can be explained in terms of a reconfinement shock that forms when relativistic flow of the jet matter collides with the external medium. The position of these knots can be used, together with information on external pressure profile, to constrain dynamical parameters of the jet. We present a semi-analytical model for the dynamical structure of reconfinement shocks, taking into account exact conservation laws both across the shock surface and in the zone of the shocked jet matter. We show that, due to the transverse pressure gradient in the shock zone, the position of the reconfinement is larger than predicted by simple models. A portion of kinetic energy is converted at the shock surface to internal energy, with efficiency increasing strongly with both bulk Lorentz factor of the jet matter and the jet half-opening angle. Our model may be useful as a framework for modeling non-thermal radiation produced within the stationary features.

  7. Long Timescale Variability of AGN with RXTE

    NASA Astrophysics Data System (ADS)

    McHardy, I. M.; Uttley, P.; Taylor, R. D.; Seymour, N.

    2004-07-01

    In this paper we review the very large contribution made by RXTE to our understanding of Active Galaxies (AGN). We discuss the relationship between AGN and Galactic Black Hole X-ray binary systems (GBHs) and show, by comparison of their powerspectral densities (PSDs) that some AGN are the equivalent of GBHs in their `high' state, rather than in their `low' state as has previously been assumed. We plot the timescale at which the PSD slope steepens from -1 to -2 against the black hole mass for a sample of AGN, and for Cyg X-1 in its high and low states. We find it is not possible to fit all AGN to the same linear scaling of break timescale with black hole mass. However broad line AGN are consistent with a linear scaling of break timescale with mass from Cyg X-1 in its low state and NLS1 galaxies scale better with Cyg X-1 in its high state, although there is an exception, NGC3227. We suggest that the relationship between black hole mass and break timescale is a function of another underlying parameter which may be accretion rate or black hole spin or, probably, both. We examine X-ray spectral variability and show how simple `flux-flux' plots can distinguish between `two-component' and `spectral pivoting' models. We also examine the relationship between the X-ray emission and that in other wavebands. In the case of X-ray/optical variability we show how cooler discs in AGN with larger mass black holes lead to greater proximity of the X-ray and optical emission regions and hence to more highly correlated variability. The very large amplitude of optical variability then rules out reprocessing as the origin of the optical emission. We show how the radio emission in NGC 4051 is strongly correlated with the X-ray emission, implying some contribution to the X-ray emission from a jet for which there is some evidence in radio images. We point out, however, that we have only studied in detail the X-ray variability of a handful of AGN. There is a strong requirement to extend such

  8. Revisiting the relationship between 6 μm and 2-10 keV continuum luminosities of AGN

    NASA Astrophysics Data System (ADS)

    Mateos, S.; Carrera, F. J.; Alonso-Herrero, A.; Rovilos, E.; Hernán-Caballero, A.; Barcons, X.; Blain, A.; Caccianiga, A.; Della Ceca, R.; Severgnini, P.

    2015-05-01

    We have determined the relation between the AGN luminosities at rest-frame 6 μm associated with the dusty torus emission and at 2-10 keV energies using a complete, X-ray-flux-limited sample of 232 AGN drawn from the Bright Ultra-hard XMM-Newton Survey. The objects have intrinsic X-ray luminosities between 1042 and 1046 erg s-1 and redshifts from 0.05 to 2.8. The rest-frame 6 μm luminosities were computed using data from the Wide-field Infrared Survey Explorer and are based on a spectral energy distribution decomposition into AGN and galaxy emission. The best-fitting relationship for the full sample is consistent with being linear, L6 μm ∝ L_{2-10 keV}^{0.99± 0.03}, with intrinsic scatter, Δ log L6 μm ˜ 0.35 dex. The L_{6 μ m}/L_{2-10 keV} luminosity ratio is largely independent of the line-of-sight X-ray absorption. Assuming a constant X-ray bolometric correction, the fraction of AGN bolometric luminosity reprocessed in the mid-IR decreases weakly, if at all, with the AGN luminosity, a finding at odds with simple receding torus models. Type 2 AGN have redder mid-IR continua at rest-frame wavelengths <12 μm and are overall ˜1.3-2 times fainter at 6 μm than type 1 AGN at a given X-ray luminosity. Regardless of whether type 1 and type 2 AGN have the same or different nuclear dusty toroidal structures, our results imply that the AGN emission at rest-frame 6 μm is not isotropic due to self-absorption in the dusty torus, as predicted by AGN torus models. Thus, AGN surveys at rest-frame ˜6 μm are subject to modest dust obscuration biases.

  9. Steps Toward Unveiling the True Population of AGN: Photometric Selection of Broad-Line AGN

    NASA Astrophysics Data System (ADS)

    Schneider, Evan; Impey, C.

    2012-01-01

    We present an AGN selection technique that enables identification of broad-line AGN using only photometric data. An extension of infrared selection techniques, our method involves fitting a given spectral energy distribution with a model consisting of three physically motivated components: infrared power law emission, optical accretion disk emission, and host galaxy emission. Each component can be varied in intensity, and a reduced chi-square minimization routine is used to determine the optimum parameters for each object. Using this model, both broad- and narrow-line AGN are seen to fall within discrete ranges of parameter space that have plausible bounds, allowing physical trends with luminosity and redshift to be determined. Based on a fiducial sample of AGN from the catalog of Trump et al. (2009), we find the region occupied by broad-line AGN to be distinct from that of quiescent or star-bursting galaxies. Because this technique relies only on photometry, it will allow us to find AGN at fainter magnitudes than are accessible in spectroscopic surveys, and thus probe a population of less luminous and/or higher redshift objects. With the vast availability of photometric data in large surveys, this technique should have broad applicability and result in large samples that will complement X-ray AGN catalogs.

  10. Satellites of radio AGN in SDSS: Insights into agn triggering and feedback

    SciTech Connect

    Pace, Cameron; Salim, Samir E-mail: salims@indiana.edu

    2014-04-10

    We study the effects of radio jets on galaxies in their vicinity (satellites) and the role of satellites in triggering radio-loud active galactic nuclei (AGNs). The study compares the aggregate properties of satellites of a sample of 7220 radio AGNs at z < 0.3 (identified by Best and Heckman from the SDSS and NVSS+FIRST surveys) to the satellites of a control sample of radio-quiet galaxies, which are matched in redshift, color, luminosity, and axis ratio, as well as by environment type: field galaxies, cluster members, and brightest cluster galaxies (BCGs). Remarkably, we find that radio AGNs exhibit on average a 50% excess (17σ significance) in the number of satellites within 100 kpc even though the cluster membership was controlled (e.g., radio BCGs have more satellites than radio-quiet BCGs, etc.). Satellite excess is not confirmed for high-excitation sources, which are only 2% of radio AGN. Extra satellites may be responsible for raising the probability for hot gas AGN accretion via tidal effects or may otherwise enhance the intensity or duration of the radio-emitting phase. Furthermore, we find that the incidence of radio AGNs among potential hosts (massive ellipticals) is similar for field galaxies and for non-BCG cluster members, suggesting that AGN fueling depends primarily on conditions in the host halo rather than the parent, cluster halo. Regarding feedback, we find that radio AGNs, either high or low excitation, have no detectable effect on star formation in their satellites, as neither induced star formation nor star formation quenching is present in more than ∼1% of radio AGN.

  11. Observational evidence for thin AGN disks

    NASA Technical Reports Server (NTRS)

    Netzer, Hagai

    1992-01-01

    AGN spectrum and spectral features, polarization, inclination, and X-ray line and continuum reflection features are discussed in a critical way in order to determine the ones that are the least model-dependent. The sign and strength of absorption and emission edges are found to be model-dependent, and relativistic broadening and shifting makes them hard to detect. The presence or absence of the predicted Lyman edge polarization feature may be used as a decisive test for thin, bare AGN disks. Other good model-independent tests are several inclination-related line and continuum correlations in big AGN samples. It is shown that electron temperature near the surface of the disk can greatly exceed the disk equilibrium temperature, which causes deviations from LTE. This effect must be incorporated into realistic disk models.

  12. γ-Ray Generation in Microquasars: the link with AGN

    NASA Astrophysics Data System (ADS)

    Latham, I. J.; Aye, K.-M.; Brown, A. M.; Chadwick, P. M.; Hadjichristidis, C. N.; Le Gallou, R.; McComb, T. J. L.; Nolan, S. J.; Orford, K. J.; Osborne, J. L.; Noutsos, A.; Rayner, S. M.

    2005-02-01

    The link between the physical processes responsible for high energy emission from relativistic jets in AGN and microquasars is investigated. A Fortran code based on an existing inhomogeneous, synchrotron self-Compton (SSC) model, for AGN is presented. The code is then applied to the AGN 3C 279 and the microquasar LS5039. Spectral energy distributions (SED's) are presented.

  13. Exposure to p,p'-DDE Alters Macrophage Reactivity and Increases Macrophage Numbers in Adipose Stromal Vascular Fraction.

    PubMed

    Mangum, Lauren H; Crow, John Allen; Stokes, John V; Howell, George E; Ross, Matthew K; Pruett, Stephen B; Chambers, Janice E

    2016-03-01

    Exposure to p,p'-DDE (DDE), the main bioaccumulative metabolite of the organochlorine insecticide p,p'-DDT, is associated with a higher prevalence of obesity, dyslipidemia, insulin resistance, metabolic syndrome, and immunomodulation. The present study was carried out to determine whether DDE perturbs adipose tissue homeostasis through modulation of macrophage function. Treatment with DDE or a cyclooxygenase-2 inhibitor prior to lipopolysaccharide exposure significantly decreased production of prostaglandins (PG) from J774a.1 macrophages in vitro. Similarly, J774A.1 cell lysates incubated with DDE or a specific cyclooxygenase-2 inhibitor (NS-398) produced significantly less PGE2 and PGF2α. Macrophage polarization studies revealed a pattern of DDE effects that were not fully consistent with a purely pro- or purely anti- M1 or M2 effect. However, DDE suppressed expression of two M1 markers (induced by an M1 stimulus) and enhanced expression of an M2 marker (induced by an M2 stimulus). Further studies including assessment of macrophage function are needed to fully characterize the effects of DDE on macrophage polarization. Obesity is characterized by an increase in the number of resident adipose tissue macrophages. To assess monocyte/macrophage recruitment to the adipose tissue in vivo, male C57Bl/6H mice were treated with 2 mg/kg DDE or corn oil vehicle for 5 days by gavage. Epididymal fat pads were digested and macrophage populations were analyzed by flow cytometry. In DDE-treated animals, there was a significant increase (37%) in F4/80(+)CD11b(+) macrophages/g of epididymal adipose over vehicle (P < .05). Together, these results suggest a role for DDE in the enhancement of adipose tissue macrophage recruitment and/or proliferation, as well as modulation of immune cell function that may contribute to the etiology of metabolic diseases associated with organochlorine exposure. PMID:26748080

  14. Fractionated neem leaf extract is safe and increases CD4+ cell levels in HIV/AIDS patients.

    PubMed

    Mbah, A U; Udeinya, I J; Shu, E N; Chijioke, C P; Nubila, T; Udeinya, F; Muobuike, Angela; Mmuobieri, Ancila; Obioma, Maria S

    2007-01-01

    The safety and effect of an acetone-water neem leaf extract (IRAB) on CD4 cells was investigated in 60 HIV/AIDS patients as part of an ongoing study to determine the influence of neem on immunity and viral load in HIV/AIDS. Patients were confirmed as HIV I or II positive, as having CD4 cell count, less than 300 cells/microL, and as antiretrovirally naïve. They were given oral IRAB (1.0 g daily for 12 weeks). Clinical and laboratory tests were carried out at baseline and at 4 weekly intervals. Thus, the patients served as their own controls. Sixty patients completed treatment. Fifty (83.33%) were completely compliant with respect to laboratory tests. Increase in mean CD4 cells, 266 cells/microL (159%), for the 50 patients was significant (P < 0.001) between baseline and week 12. Erythrocyte sedimentation rate (64 mm/hr at baseline) was 16 mm/hr at week 12, whereas total number of incidences of HIV/AIDS-related pathologies decreased from 120 at baseline to 5. Mean bodyweight, hemoglobin concentration, and lymphocyte differential count increased significantly by 12% (P < 0.05), 24% (P < 0.0001), and 20% (P < 0.0001), respectively. There were no adverse effects and no abnormalities in kidney and liver function parameters. The results support the safety of IRAB in HIV/AIDS, and its significant influence on CD4 cells may be useful in the formulation of multidrug combination therapies for HIV/AIDS. However, its antiretroviral activity is being evaluated in our laboratory. PMID:17667213

  15. FE Features in Highly Obscured AGN

    NASA Technical Reports Server (NTRS)

    Schachter, Jonathan F.

    1999-01-01

    This final report is a summary of the combined study of ASCA (Advanced Satellite for Cosmology and Astrophysics) observations of NGC 7582 with archival ROSAT HRI (High Resolution Imager) and PSPC (Position Sensitive Proportional Counter) data. These observations were important in that they established that X-ray emission in NGC 7582, the most narrow-line of NLXGs (narrow-line X-ray galaxies), is associated with an AGN (Active Galactic Nuclei). Thus implying that all NLXGs are obscured AGN, as has been hypothesized to explain the X-ray spectral background paradox.

  16. Modeling optical and UV polarization of AGNs. III. From uniform-density to clumpy regions

    NASA Astrophysics Data System (ADS)

    Marin, F.; Goosmann, R. W.; Gaskell, C. M.

    2015-05-01

    Context. A growing body of evidence suggests that some, if not all, scattering regions of active galactic nuclei (AGNs) are clumpy. The inner AGN components cannot be spatially resolved with current instruments and must be studied by numerical simulations of observed spectroscopy and polarization data. Aims: We run radiative transfer models in the optical/UV for a variety of AGN reprocessing regions with different distributions of clumpy scattering media. We obtain geometry-sensitive polarization spectra and images to improve our previous AGN models and their comparison with the observations. Methods: We use the latest public version 1.2 of the Monte Carlo code stokes presented in the first two papers of this series to model AGN reprocessing regions of increasing morphological complexity. We replace previously uniform-density media with up to thousands of constant-density clumps. We couple a continuum source to fragmented equatorial scattering regions, polar outflows, and toroidal obscuring dust regions and investigate a wide range of geometries. We also consider different levels of fragmentation in each scattering region to evaluate the importance of fragmentation for the net polarization of the AGN. Results: In comparison with uniform-density models, equatorial distributions of gas and dust clouds result in grayer spectra and show a decrease in the net polarization percentage at all lines of sight. The resulting polarization position angle depends on the morphology of the clumpy structure, with extended tori favoring parallel polarization while compact tori produce orthogonal polarization position angles. In the case of polar scattering regions, fragmentation increases the net polarization unless the cloud filling factor is small. A complete AGN model constructed from the individual, fragmented regions can produce low polarization percentages (<2%), with a parallel polarization angle for observer inclinations up to 70° for a torus half opening angle of 60°. For

  17. The AGN Contribution to Galaxy Merger Infrared Luminosities

    NASA Astrophysics Data System (ADS)

    Rosenthal, Lee; Hayward, Christopher C.; Smith, Howard; Ashby, Matthew; Hung, Chao-Ling; Martinez-Galarza, Rafael; Weiner, Aaron; Zezas, Andreas; Lanz, Lauranne

    2015-01-01

    We investigate the contribution of AGN activity to the infrared luminosity of interacting galaxies by analyzing dust radiative transfer calculations of a hydrodynamically simulated merger, created with the code GADGET-2. We focus on emission in the mid-IR to far-IR wavelength ranges, and trace the luminosity density of an interacting gas-rich galaxy pair throughout its evolution. We find that the AGN contribution to IR luminosity is greatest during and immediately after coalescence of the galaxies' central black holes. This period lasts roughly 80 Myr, during which time the increased influx of gas to the center of the merger increases the total luminosity by a factor of a thousand or more due to both increased star formation rate (SFR) and black hole accretion. We compare different interstellar medium models used to describe sub-resolution gas and dust clouds in the radiative transfer calculations by studying the color evolution of our merger in the Herschel Space Observatory photometric filter bands, and compare the results to Herschel observations. We conclude that using infrared luminosity as a simple surrogate for SFR can overestimate the true rate, due to the contribution of AGN or other dust heating mechanisms. This conclusion has an especially significant impact in assessing the star formation activity in high-redshift galaxies for which luminosity (the best measured property) may not accurately measure the SFR, and in cases where the molecular gas content can differ from that of local systems. Further work will extend this analysis to simulations of mergers between late-type galaxies. This work was supported in part by the NSF REU and DOD ASSURE programs under NSF grant no. 1262851, by the Smithsonian Institution and by NASA grant NNX14AJ6IG.

  18. Complete Hard X-Ray Surveys, AGN Luminosity Functions and the X-Ray Background

    NASA Technical Reports Server (NTRS)

    Tueller, Jack

    2011-01-01

    AGN are believed to make up most of the Cosmic X-Ray Background (CXB) above a few keV, but this background cannot be fully resolved at energies less than 10 keV due to absorption. The Swift/BAT and INTEGRAL missions are performing the first complete hard x-ray surveys with minimal bias due to absorption. The most recent results for both missions will be presented. Although the fraction of the CXB resolved by these surveys is small, it is possible to derive unbiased number counts and luminosity functions for AGN in the local universe. The survey energy range from 15-150 keV contains the important reflection and cutoff spectral features dominate the shape of the AGN contribution to the CXB. Average spectral characteristics of survey detected AGN will be presented and compared with model distributions. The numbers of hard x-ray blazars detected in these surveys are finally sufficient to estimate this important component's contribution the cosmic background. Constraints on CXB models and their significance will be discussed.

  19. On the Star Formation-AGN Connection at zeta (is) approximately greater than 0.3

    NASA Technical Reports Server (NTRS)

    LaMassa, Stephanie M.; Heckman, T. M.; Ptak, Andrew; Urry, C. Megan

    2013-01-01

    Using the spectra of a sample of approximately 28,000 nearby obscured active galaxies from Data Release 7 of the Sloan Digital Sky Survey (SDSS), we probe the connection between active galactic nucleus (AGN) activity and star formation over a range of radial scales in the host galaxy. We use the extinction-corrected luminosity of the [O iii] 5007A line as a proxy of intrinsic AGN power and supermassive black hole (SMBH) accretion rate. The star formation rates (SFRs) are taken from the MPA-JHU value-added catalog and are measured through the 3 inch SDSS aperture. We construct matched samples of galaxies covering a range in redshifts. With increasing redshift, the projected aperture size encompasses increasing amounts of the host galaxy. This allows us to trace the radial distribution of star formation as a function of AGN luminosity. We find that the star formation becomes more centrally concentrated with increasing AGN luminosity and Eddington ratio. This implies that such circumnuclear star formation is associated with AGN activity, and that it increasingly dominates over omnipresent disk star formation at higher AGN luminosities, placing critical constraints on theoretical models that link host galaxy star formation and SMBH fueling. We parameterize this relationship and find that the star formation on radial scales (is) less than 1.7 kpc, when including a constant disk component, has a sub-linear dependence on SMBH accretion rate: SFR in proportion to solar mass(sup 0.36), suggesting that angular momentum transfer through the disk limits accretion efficiency rather than the supply from stellar mass loss.

  20. Discovery of a population of bulgeless galaxies with extremely red MID-IR colors: Obscured AGN activity in the low-mass regime?

    SciTech Connect

    Satyapal, S.; Secrest, N. J.; McAlpine, W.; Rosenberg, J. L.; Ellison, S. L.; Fischer, J.

    2014-04-01

    In contrast to massive, bulge hosting galaxies, very few supermassive black holes (SMBHs) are known in either low-mass or bulgeless galaxies. Such a population could provide clues to the origins of SMBHs and to secular pathways for their growth. Using the all-sky Wide-field Infrared Survey Explorer (WISE ) survey, and bulge-to-disk decompositions from the Sloan Digital Sky Survey (SDSS) Data Release 7, we report the discovery of a population of local (z < 0.3) bulgeless disk galaxies with extremely red mid-infrared colors which are highly suggestive of a dominant active galactic nucleus (AGN), despite having no optical AGN signatures in their SDSS spectra. Using various mid-infrared selection criteria from the literature, there are between 30 and over 300 bulgeless galaxies with possible AGNs. Other known scenarios that can heat the dust to high temperatures do not appear to explain the observed colors of this sample. If these galaxies are confirmed to host AGNs, this study will provide a breakthrough in characterizing the properties of SMBHs in the low bulge mass regime and in understanding their relation with their host galaxies. Mid-infrared selection identifies AGNs that dominate their host galaxy's emission and therefore reveal a different AGN population than that uncovered by optical studies. We find that the fraction of all galaxies identified as candidate AGNs by WISE is highest at lower stellar masses and drops dramatically in higher mass galaxies, in striking contrast to the findings from optical studies.

  1. A Global Picture of AGN Winds

    NASA Technical Reports Server (NTRS)

    Kazanas, D.; Fukumura, K.

    2011-01-01

    We present a unified structure for accretion powered sources across their entire luminosity range from accreting galactic black holes to the most luminous quasars, with emphasis on AGN and their phenomenology. Central to this end is the notion of MHD winds launched from the accretion disks that power these objects. This work similar in spirit to that of Elvis of more that a decade ago, provides, on one hand, only the broadest characteristics of these objects, but on the other, also scaling laws that allow one to make contact with objects of different luminosity. The conclusion of this work is that AGN phenomenology can be accounted for in terms of dot(m), the wind mass flux in units of the Eddington value, the observer's inclination angle theta and alpha_OX the logarithmic slope between UV and X-ray flares. However given the well known correlation between alpha(sub ox) and UV Luminosity, we conclude that the AGN structure depends on only two parameters. The small number of model parameters hence suggests that an understanding of the global AGN properties maybe within reach.

  2. Mid-IR Observations of AGN

    NASA Astrophysics Data System (ADS)

    Packham, Christopher C.; Alonso Herrero, Almudena; Levenson, Nancy A.; Piratas AGN Group

    2016-01-01

    We present new observations of AGN, predominantly from the 10.4m GranTeCan. These observations are modeled and interpreted within the context of the clumpy torus models. In this poster we present our recent results and interpretation of the model outputs.

  3. Mabel Agnes Elliott, We Hardly Knew You

    ERIC Educational Resources Information Center

    McGonigal, Kathryn; Galliher, John F.

    2008-01-01

    Sociologist Mabel Agnes Elliott was elected the fourth president of the Society for the Study of Social Problems in 1956-1957 and was the first woman to hold this position. She was an anti-war activist, a feminist and a creative and diligent writer. Yet she experienced many challenges. The Federal Bureau of Investigation kept an active file on…

  4. The Horizon-AGN Simulation: Morphological Diversity of Galaxies ,Promoted by AGN Feedback

    NASA Astrophysics Data System (ADS)

    Dubois, Yohan; Peirani, Sébastien; Pichon, Christophe; Devriendt, Julien; Gavazzi, Raphaël; Welker, Charlotte; Volonteri, Marta

    2016-09-01

    The interplay between cosmic gas accretion onto galaxies and galaxy mergers drives the observed morphological diversity of galaxies. By comparing the state-of-the-art hydrodynamical cosmological simulations HORIZON-AGN and HORIZON-NOAGN, we unambiguously identify the critical role of Active Galactic Nuclei (AGN) in setting up the correct galaxy morphology for the massive end of the population. With AGN feedback, typical kinematic and morpho-metric properties of galaxy populations as well as the galaxy-halo mass relation are in much better agreement with observations. Only AGN feedback allows massive galaxies at the center of groups and clusters to become ellipticals, while without AGN feedback those galaxies reform discs. It is the merger-enhanced AGN activity that is able to freeze the morphological type of the post-merger remnant by durably quenching its quiescent star formation. Hence morphology is shown not to be purely driven by mass but also by the nature of cosmic accretion: at constant galaxy mass, ellipticals are galaxies that are mainly assembled through mergers, while discs are preferentially built from the in situ star formation fed by smooth cosmic gas infall.

  5. X-ray selected AGN in a Merging Cluster Environment

    NASA Astrophysics Data System (ADS)

    Norman, Dara; Coldwell, Georgina; Soechting, Ilona

    2010-08-01

    Although a general understanding of the overall AGN population is being addressed by optical large area surveys, a complete picture of cluster AGN is hampered by survey biases and a lack of information about AGN environments where we can trace cluster interactions. Optically selected AGN are under-represented in cluster environments due to color selection criteria insensitive to red and dusty sources. X-ray selection of AGN can overcome this bias. Hierarchical simulations suggest the gravitational processes which govern the evolution of clusters also have a role in AGN triggering, and AGN feedback is critically important to galaxy evolution. Confirmation of models requires comparisons not just of the cluster galaxy population, but also of the distributions of AGN in clusters especially forming clusters, which are not fully identified in surveys. Weak lensing cluster selection can overcome this bias. We propose to obtain GMOS-S spectra for a sample of 23 X-ray selected , optically faint (20 with R>20.3) AGN cluster candidates in an X-ray cluster discovered by its weak lensing shear signal. This cluster is unique in the large number of 1) X-ray AGN candidates identified in its environment and 2) X-ray sub-clusters identified. We require redshift data to identify AGN cluster members.

  6. AGN identification and host galaxies properties in the MOSDEF survey

    NASA Astrophysics Data System (ADS)

    Azadi, Mojegan; Coil, Alison L.; MOSDEF team

    2016-06-01

    We present new results on the identification and host galaxy properties of X-ray, IR and optically-selected AGN at 1.4 < z < 3.8, using spectroscopic data from the on-going MOSDEF survey, which is obtaining rest-frame optical spectra of ~1,500 galaxies and AGN using the new Keck/MOSFIRE instrument. We find clear selection effects when identifying AGN at different wavelengths, in that optically-selected AGN are more likely to be found in galaxies with low SFR, while IR AGN are typically found in galaxies with higher SFR. There is also a bias against finding AGN at any wavelength in low mass galaxies. We find that optical AGN selection identifies less powerful AGN that may be obscured at other wavelengths. Combining the AGN we identify at different wavelengths, we find that AGN host galaxies have similar stellar age and dust content as inactive galaxies of the same stellar mass. Finally, we do not find a significant correlation between either SFR or stellar mass and L[OIII], which argues against the presence of strong AGN feedback.

  7. Long-term combined chemical and manure fertilizations increase soil organic carbon and total nitrogen in aggregate fractions at three typical cropland soils in China.

    PubMed

    He, Y T; Zhang, W J; Xu, M G; Tong, X G; Sun, F X; Wang, J Z; Huang, S M; Zhu, P; He, X H

    2015-11-01

    Soil organic carbon (SOC), total nitrogen (TN), microbial biomass carbon (MBC) and nitrogen (MBN) are important factors of soil fertility. However, effects of the combined chemical fertilizer and organic manure or straw on these factors and their relationships are less addressed under long-term fertilizations. This study addressed changes in SOC, TN, MBC and MBN at 0-20 cm soil depth under three 17 years (September 1990-September 2007) long-term fertilization croplands along a heat and water gradient in China. Four soil physical fractions (coarse free and fine free particulate organic C, cfPOC and ffPOC; intra-microaggregate POC, iPOC; and mineral associated organic C, MOC) were examined under five fertilizations: unfertilized control, chemical nitrogen (N), phosphorus (P) and potassium (K) (NPK), NPK plus straw (NPKS, hereafter straw return), and NPK plus manure (NPKM and 1.5NPKM, hereafter manure). Compared with Control, manure significantly increased all tested parameters. SOC and TN in fractions distributed as MOC > iPOC > cfPOC > ffPOC with the highest increase in cfPOC (329.3%) and cfPTN (431.1%), and the lowest in MOC (40.8%) and MTN (45.4%) under manure. SOC significantly positively correlated with MBC, cfPOC, ffPOC, iPOC and MOC (R(2) = 0.51-0.84, P < 0.01), while TN with cfPTN, ffPTN, iPTN and MTN (R(2) = 0.45-0.79, P < 0.01), but not with MBN, respectively. Principal component analyses explained 86.9-91.2% variance of SOC, TN, MBC, MBN, SOC and TN in each fraction. Our results demonstrated that cfPOC was a sensitive SOC indicator and manure addition was the best fertilization for improving soil fertility while straw return should take into account climate factors in Chinese croplands. PMID:26119378

  8. A POWERFUL AGN OUTBURST IN RBS 797

    SciTech Connect

    Cavagnolo, K. W.; McNamara, B. R.; Wise, M. W.; Nulsen, P. E. J.; Gitti, M.; Brueggen, M.; Rafferty, D. A.

    2011-05-10

    Utilizing {approx}50 ks of Chandra X-Ray Observatory imaging, we present an analysis of the intracluster medium (ICM) and cavity system in the galaxy cluster RBS 797. In addition to the two previously known cavities in the cluster core, the new and deeper X-ray image has revealed additional structure associated with the active galactic nucleus (AGN). The surface brightness decrements of the two cavities are unusually large and are consistent with elongated cavities lying close to our line of sight. We estimate a total AGN outburst energy and mean jet power of {approx}(3-6) x 10{sup 60} erg and {approx}(3-6) x 10{sup 45} erg s{sup -1}, respectively, depending on the assumed geometrical configuration of the cavities. Thus, RBS 797 is apparently among the most powerful AGN outbursts known in a cluster. The average mass accretion rate needed to power the AGN by accretion alone is {approx}1 M{sub sun} yr{sup -1}. We show that accretion of cold gas onto the AGN at this level is plausible, but that Bondi accretion of the hot atmosphere is probably not. The brightest cluster galaxy (BCG) harbors an unresolved, non-thermal nuclear X-ray source with a bolometric luminosity of {approx}2 x 10{sup 44} erg s{sup -1}. The nuclear emission is probably associated with a rapidly accreting, radiatively inefficient accretion flow. We present tentative evidence that star formation in the BCG is being triggered by the radio jets and suggest that the cavities may be driving weak shocks (M {approx} 1.5) into the ICM, similar to the process in the galaxy cluster MS 0735.6+7421.

  9. A SEARCH FOR BINARY ACTIVE GALACTIC NUCLEI: DOUBLE-PEAKED [O III] AGNs IN THE SLOAN DIGITAL SKY SURVEY

    SciTech Connect

    Smith, K. L.; Shields, G. A.; McMullen, C. C.; Salviander, S.; Bonning, E. W.; Rosario, D. J. E-mail: shields@astro.as.utexas.ed E-mail: erin.bonning@yale.ed

    2010-06-10

    We present active galactic nuclei (AGNs) from the Sloan Digital Sky Survey (SDSS) having double-peaked profiles of [O III]{lambda}{lambda}5007, 4959 and other narrow emission lines, motivated by the prospect of finding candidate binary AGNs. These objects were identified by means of a visual examination of 21,592 quasars at z < 0.7 in SDSS Data Release 7 (DR7). Of the spectra with adequate signal-to-noise, 148 spectra exhibit a double-peaked [O III] profile. Of these, 86 are Type 1 AGNs and 62 are Type 2 AGNs. Only two give the appearance of possibly being optically resolved double AGNs in the SDSS images, but many show close companions or signs of recent interaction. Radio-detected quasars are three times more likely to exhibit a double-peaked [O III] profile than quasars with no detected radio flux, suggesting a role for jet interactions in producing the double-peaked profiles. Of the 66 broad-line (Type 1) AGNs that are undetected in the FIRST survey, 0.9% show double-peaked [O III] profiles. We discuss statistical tests of the nature of the double-peaked objects. Further study is needed to determine which of them are binary AGNs rather than disturbed narrow line regions, and how many additional binaries may remain undetected because of insufficient line-of-sight velocity splitting. Previous studies indicate that 0.1% of SDSS quasars are spatially resolved binaries, with typical spacings of {approx}10-100 kpc. If a substantial fraction of the double-peaked objects are indeed binaries, then our results imply that binaries occur more frequently at smaller separations (<10 kpc). This suggests that simultaneous fueling of both black holes is more common as the binary orbit decays through these spacings.

  10. The Cosmological Impact of AGN Outflows: Measuring Absolute Abundances and Kinetic Luminosities

    NASA Astrophysics Data System (ADS)

    Arav, Nahum

    2009-07-01

    AGN outflows are increasingly invoked as a major contributor to the formation and evolution of supermassive black holes, their host galaxies, the surrounding IGM, and cluster cooling flows. Our HST/COS proposal will determine reliable absolute chemical abundances in six AGN outflows, which influences several of the processes mentioned above. To date there is only one such determination, done by our team on Mrk 279 using 16 HST/STIS orbits and 100 ksec of FUSE time. The advent of COS and its high sensitivity allows us to choose among fainter objects at redshifts high enough to preclude the need for FUSE. This will allow us to determine the absolute abundances for six AGN {all fainter than Mrk 279} using only 40 HST COS orbits. This will put abundances studies in AGN on a firm footing, an elusive goal for the past four decades. In addition, prior FUSE observations of four of these targets indicate that it is probable that the COS observations will detect troughs from excited levels of C III. These will allow us to measure the distances of the outflows and thereby determine their kinetic luminosity, a major goal in AGN feedback research. We will use our state of the art column density extraction methods and velocity-dependent photoionization models to determine the abundances and kinetic luminosity. Previous AGN outflow projects suffered from the constraints of deciding what science we could do using ONE of the handful of bright targets that were observable. With COS we can choose the best sample for our experiment. As an added bonus, most of the spectral range of our targets has not been observed previously, greatly increasing the discovery phase space.

  11. Microcomputed tomographic analysis of human condyles in unilateral condylar hyperplasia: increased cortical porosity and trabecular bone volume fraction with reduced mineralisation.

    PubMed

    Karssemakers, L H E; Nolte, J W; Tuinzing, D B; Langenbach, G E J; Raijmakers, P G; Becking, A G

    2014-12-01

    Unilateral condylar hyperplasia or hyperactivity is a disorder of growth that affects the mandible, and our aim was to visualise the 3-dimensional bony microstructure of resected mandibular condyles of affected patients. We prospectively studied 17 patients with a clinical presentation of progressive mandibular asymmetry and an abnormal single-photon emission computed tomographic (SPECT) scan. All patients were treated by condylectomy to arrest progression. The resected condyles were scanned with micro-CT (18 μm resolution). Rectangular volumes of interest were selected in 4 quadrants (lateromedial and superoinferior) of the trabecular bone of each condyle. Variables of bone architecture (volume fraction, trabecular number, thickness, and separation, degree of mineralisation, and degree of structural anisotrophy) were calculated with routine morphometric software. Eight of the 17 resected condyles showed clear destruction of the subchondral layer of cortical bone. There was a significant superoinferior gradient for all trabecular variables. Mean (SD) bone volume fraction (25.1 (6) %), trabecular number (1.69 (0.26) mm(-1)), trabecular thickness (0.17 (0.03) mm), and degree of mineralisation (695.39 (39.83) mg HA/cm(3)) were higher in the superior region. Trabecular separation (0.6 (0.16) mm) and structural anisotropy (1.84 (0.28)) were higher in the inferior region. The micro-CT analysis showed increased cortical porosity in many of the condyles studied. It also showed a higher bone volume fraction, greater trabecular thickness and trabecular separation, greater trabecular number, and less mineralisation in the condyles of the 17 patients compared with the known architecture of unaffected mandibular condyles. PMID:25219775

  12. [O iii] λ5007 and X-Ray Properties of a Complete Sample of Hard X-Ray Selected AGNs in the Local Universe

    NASA Astrophysics Data System (ADS)

    Ueda, Y.; Hashimoto, Y.; Ichikawa, K.; Ishino, Y.; Kniazev, A. Y.; Väisänen, P.; Ricci, C.; Berney, S.; Gandhi, P.; Koss, M.; Mushotzky, R.; Terashima, Y.; Trakhtenbrot, B.; Crenshaw, M.

    2015-12-01

    We study the correlation between the [O iii] λ5007 and X-ray luminosities of local active galactic nuclei (AGNs), using a complete, hard X-ray (>10 keV) selected sample in the Swift/BAT 9-month catalog. From our optical spectroscopic observations at the South African Astronomical Observatory and the literature, a catalog of [O iii] λ5007 line flux for all 103 AGNs at Galactic latitudes of | b| \\gt 15^\\circ is compiled. Significant correlations with intrinsic X-ray luminosity ({L}{{X}}) are found for both observed ({L}[{{O} {{III}}] }) and extinction-corrected ({L}[{{O} {{III}}]}{{cor}}) luminosities, separately for X-ray unabsorbed and absorbed AGNs. We obtain the regression form of {L}[{{O} {{III}}] } \\propto \\{L}2-10\\{keV}1.18+/- 0.07 and {L}[{{O} {{III}}]}{{cor}} \\propto \\{L}2-10\\{keV}1.16+/- 0.09 from the whole sample. The absorbed AGNs with low (<0.5%) scattering fractions in soft X-rays show on average smaller {L}[{{O} {{III}}]}/{L}{{X}} and {L}[{{O} {{III}}]}{{cor}}/{L}{{X}} ratios than the other absorbed AGNs, while those in edge-on host galaxies do not. These results suggest that a significant fraction of this population is buried in tori with small opening angles. By using these {L}[{{O} {{III}}] } versus {L}{{X}} correlations, the X-ray luminosity function (LF) of local AGNs (including Compton-thick AGNs) in a standard population synthesis model gives much better agreement with the [O iii] λ5007 LF derived from the Sloan Digital Sky Survey than previously reported. This confirms that hard X-ray observations are a very powerful tool to find AGNs with high completeness.

  13. A tale of two feedbacks: Star formation in the host galaxies of radio AGNs

    SciTech Connect

    Karouzos, Marios; Im, Myungshin; Jeon, Yiseul; Kim, Ji Hoon; Trichas, Markos; Goto, Tomo; Malkan, Matt; Ruiz, Angel; Lee, Hyung Mok; Kim, Seong Jin; Oi, Nagisa; Matsuhara, Hideo; Takagi, Toshinobu; Murata, K.; Wada, Takehiko; Wada, Kensuke; Shim, Hyunjin; Hanami, Hitoshi; Serjeant, Stephen; White, Glenn J.; and others

    2014-04-01

    Several lines of argument support the existence of a link between activity at the nuclei of galaxies, in the form of an accreting supermassive black hole, and star formation activity in these galaxies. Radio jets have long been argued to be an ideal mechanism that allows active galactic nuclei (AGNs) to interact with their host galaxies and affect star formation. We use a sample of radio sources in the North Ecliptic Pole (NEP) field to study the nature of this putative link, by means of spectral energy distribution (SED) fitting. We employ the excellent spectral coverage of the AKARI infrared space telescope and the rich ancillary data available in the NEP to build SEDs extending from UV to far-IR wavelengths. We find a significant AGN component in our sample of relatively faint radio sources (AGN component and that of star formation in the host galaxy, independent of the radio luminosity. In contrast, for narrow redshift and AGN luminosity ranges, we find that increasing radio luminosity leads to a decrease in the specific star formation rate. The most radio-loud AGNs are found to lie on the main sequence of star formation for their respective redshifts. For the first time, we potentially see such a two-sided feedback process in the same sample. We discuss the possible suppression of star formation, but not total quenching, in systems with strong radio jets, that supports the maintenance nature of feedback from radio AGN jets.

  14. Isolation of S9 fractions from mouse and rat with increased enzyme activities after repeated administration of cytochrome P-450 and P-448 inducers.

    PubMed

    Paolini, M; Sapigni, E; Hrelia, P; Grilli, S; Cantelli-Forti, G

    1988-05-01

    Cytochrome P-450 (cyt P-450), NADPH cytochrome P-450 reductase and various microsomal monooxygenase activities [e.g. aminopyrine N-demethylase, p-nitroanisole O-demethylase, dinemorphan N-demethylase, ethoxycoumarin O-deethylase and ethoxyresorufin O-deethylase (ERD)], were determined in hepatic post-mitochondrial supernatant from mice and rats. Experiments were performed on male and female animals treated with a combination of sodium phenobarbital and beta-naphthoflavone according to the standard protocol schedule for short-term genotoxicity testing. A second inductive treatment after 2, 3, 4 or 5 weeks was provided. The increase in cyt P-450 and in all enzymatic activities measured was enhanced in both species by a second induction treatment, particularly when given after 4 weeks. ERD activity was the only monooxygenase activity which was sex-dependent, being more active in female than in male animals. To extend the biochemical data, experiments were performed with the proposed S9 fractions on styrene, which previously has proved difficult to detect in short-term in vitro mutagenicity tests. Using the new induction conditions positive results were obtained with the D7 strain of Saccharomyces cerevisiae. It was concluded that a simple pre-induction of the animals 3-4 weeks before the main induction treatment leads to a more active S9 fraction for in vitro genotoxicity studies. PMID:3045486

  15. Flavanoid-rich fraction from Sageretia theezans leaves scavenges reactive oxygen radical species and increases the resistance of low-density lipoprotein to oxidation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To explore their bioactive fractions, S. theezans leaves were extracted 2 with 60% acetone and then fractionated sequentially with hexane, ethyl acetate, and water. ROS (HOCl, ONOO-, and O2 deg -) scavenging activity, ORAC value and total phenolic content of each fraction were investigated. The ethy...

  16. Feasibility of asymmetrical flow field-flow fractionation as a method for detecting protective antigen by direct recognition of size-increased target-captured nanoprobes.

    PubMed

    Shin, Kayeong; Choi, Jaeyeong; Cho, Jun-Haeng; Yoon, Moon-Young; Lee, Seungho; Chung, Hoeil

    2015-11-27

    Asymmetrical flow field-flow fractionation (AF4) was evaluated as a potential analytical method for detection of a protective antigen (PA), an Anthrax biomarker. The scheme was based on the recognition of altered AF4 retention through the generation of the size-increased Au nanoparticle probes as a result of PA binding, in which a PA-selective peptide was conjugated on the probe surface. In the visible absorption-based AF4 fractograms, the band position shifted to a longer retention time as the PA concentration increased due to the presence of probe bound with PAs. The shift was insignificant when the concentration was relatively low at 84.3pM. To improve sensitivity, two separate probes conjugated with two different peptides able to bind on different PA epitopes were used together. The band shift then became distinguishable even at 84.3pM of PA sample. The formation of larger PA-probe inter-connected species using the dual-probe system was responsible for the enhanced band shift. In parallel, the feasibility of surface-enhanced Raman scattering (SERS) as a potential AF4 detection method was also evaluated. In the off-line SERS fractogram constructed using fractions collected during AF4 separation, a band shift was also observed for the 84.3pM PA sample, and the band intensity was higher when using the dual-probe system. The combination of AF4 and SERS is promising for the detection of PA and will become a potential tool if the reproducibility of SERS measurement is improved. PMID:26482872

  17. The effect of AGN feedback on the X-ray morphologies of clusters: Simulations vs. observations

    NASA Astrophysics Data System (ADS)

    Chon, Gayoung; Puchwein, Ewald; Böhringer, Hans

    2016-07-01

    , which increases the tension with observations. When classified as non-relaxed or relaxed according to their w and P3/P0 values, we find that there are no relaxed clusters in the simulations with the AGN feedback. This suggests that not only global cluster properties, like LX and T, and radial profiles should be used to compare and to calibrate simulations with observations, but also substructure measures like centre shifts and power ratios. Finally, we discuss what changes in the simulations might ease the tension with observational constraints on these quantities.

  18. Massive molecular outflows and evidence for AGN feedback from CO observations

    NASA Astrophysics Data System (ADS)

    Cicone, C.; Maiolino, R.; Sturm, E.; Graciá-Carpio, J.; Feruglio, C.; Neri, R.; Aalto, S.; Davies, R.; Fiore, F.; Fischer, J.; García-Burillo, S.; González-Alfonso, E.; Hailey-Dunsheath, S.; Piconcelli, E.; Veilleux, S.

    2014-02-01

    We study the properties of massive, galactic-scale outflows of molecular gas and investigate their impact on galaxy evolution. We present new IRAM PdBI CO(1-0) observations of local ultra-luminous infrared galaxies (ULIRGs) and quasar-hosts: a clear signature of massive and energetic molecular outflows, extending on kpc scales, is found in the CO(1-0) kinematics of four out of seven sources, with measured outflow rates of several 100 M⊙ yr-1. We combine these new observations with data from the literature, and explore the nature and origin of massive molecular outflows within an extended sample of 19 local galaxies. We find that starburst-dominated galaxies have an outflow rate comparable to their star formation rate (SFR), or even higher by a factor of ~2-4, implying that starbursts can indeed be effective in removing cold gas from galaxies. Nevertheless, our results suggest that the presence of an active galactic nucleus (AGN) can boost the outflow rate by a large factor, which is found to increase with the LAGN/Lbol ratio. The gas depletion time scales due to molecular outflows are anti-correlated with the presence and luminosity of an AGN in these galaxies, and range from a few hundred million years in starburst galaxies down to just a few million years in galaxies hosting powerful AGNs. In quasar hosts, the depletion time scales due to the outflow are much shorter than the depletion time scales due to star formation. We estimate the outflow kinetic power and find that, for galaxies hosting powerful AGNs, it corresponds to about 5% of the AGN luminosity, as expected by models of AGN feedback. Moreover, we find that momentum rates of about 20 LAGN/c are common among the AGN-dominated sources in our sample. For "pure" starburst galaxies, our data tentatively support models in which outflows are mostly momentum-driven by the radiation pressure from young stars onto dusty clouds. Overall, our results indicate that, although starbursts are effective in powering

  19. AGN feedback in the Perseus cluster

    NASA Astrophysics Data System (ADS)

    Gendron-Marsolais, Marie-Lou; Hlavacek-Larrondo, Julie; Clarke, Tracy E.; Intema, Huib; Fabian, Andrew C.; Taylor, Gregory B.; Blundell, Katherine

    2016-04-01

    Deep Chandra images of the Perseus cluster of galaxies have revealed a succession of cavities created by the jets of the central supermassive black hole, pushing away the X-ray emitting gas and leaving bubbles filled with radio emission. Perseus is one of the rare examples showing buoyantly rising lobes from past radio outbursts, characterized by a steep spectral index and known as ghost cavities. All of these structures trace the complete history of mechanical AGN feedback over the past 500 Myrs. I will present results on new, ultra deep 230-470 MHz JVLA data. This low-frequency view of the Perseus cluster will probe the old radio-emitting electron population and will allow us to build the most detailed map of AGN feedback in a cluster thus far.

  20. Discovering Rare AGN with Stripe 82X

    NASA Astrophysics Data System (ADS)

    LaMassa, S.; Urry, C.; Cappelluti, N.; Comastri, A.; Glikman, E.; Richards, G.; Boehringer, H.; Murray, S.; Civano, F.

    2014-07-01

    We have begun a wide-area survey overlapping the Sloan Digital Sky Survey (SDSS) region Stripe 82 which contains extensive multi-wavelength coverage from both ground- and space-based observatories. With the initial data release of Stripe 82X, covering 16.5 deg^{2} from XMM-Newton and Chandra, we identified ˜3300 X-ray sources, including the highest spectroscopically confirmed X-ray selected quasar to date (z = 5.86). I will review the science highlights of this survey so far, including the space density of high luminosity AGN and results from our ground-based campaign to target optically dull, infrared bright targets, which are prime candidates for obscured AGN at high redshift. I will conclude with a discussion of what we expect to learn with the additional 20 deg^{2} of coverage with XMM-Newton awarded to us in AO 13, which will more than double our current survey area.

  1. The universal spectrum of AGNs and QSOs

    NASA Technical Reports Server (NTRS)

    Kazanas, D.

    1985-01-01

    The effects of the feedback of e(+)-e(-) pair reinjection in a plasma due to photon photon absorption of its own radiation are examined. A mechanism is presented which can produce an electron distribution function that can account for the overall spectral distribution of radiation of AGNs and QSOs and the specific slopes observed in the IR to UV and 2-50 keV bands. It is interesting to note that the necessary condition for this mechanism to work (i.e., most of energy injected at e(M sub e)(C sup 2) is realized in the accretion shock model of Kazanas and Ellison. This mechanism involves only one free parameter the compactness of the sources, L/R, whose mean value can also account for the diffuse gamma ray background in terms of AGNs.

  2. AGN feedback in galaxy clusters and groups

    NASA Astrophysics Data System (ADS)

    Hardcastle, Martin

    2016-07-01

    Mechanical feedback via Active Galactic Nuclei (AGN) jets in the centres of galaxy groups and clusters is a crucial ingredient in current models of galaxy formation and cluster evolution. Jet feedback is believed to regulate gas cooling and thus star formation in the most massive galaxies, but a robust physical understanding of this feedback mode is currently lacking. Athena will provide (1) the first kinematic measurements on relevant spatial scales of the hot gas in galaxy, group and cluster haloes as it absorbs the impact of AGN jets, and (2) vastly improved ability to map thermodynamic conditions on scales well-matched to the jets, lobes and gas disturbances produced by them. I will present new predictions of Athena's ability to measure the energetic impact of powerful jets based on our most recent set of numerical models.

  3. Simulations of the OzDES AGN reverberation mapping project

    NASA Astrophysics Data System (ADS)

    King, Anthea L.; Martini, Paul; Davis, Tamara M.; Denney, K. D.; Kochanek, C. S.; Peterson, Bradley M.; Skielboe, Andreas; Vestergaard, Marianne; Huff, Eric; Watson, Darach; Banerji, Manda; McMahon, Richard; Sharp, Rob; Lidman, C.

    2015-10-01

    As part of the Australian spectroscopic dark energy survey (OzDES) we are carrying out a large-scale reverberation mapping study of ≥500 quasars over five years in the 30 deg2 area of the Dark Energy Survey (DES) supernova fields. These quasars have redshifts ranging up to 4 and have apparent AB magnitudes between 16.8 mag < r < 22.5 mag. The aim of the survey is to measure time lags between fluctuations in the quasar continuum and broad emission-line fluxes of individual objects in order to measure black hole masses for a broad range of active galactic nuclei (AGN) and constrain the radius-luminosity (R-L) relationship. Here we investigate the expected efficiency of the OzDES reverberation mapping campaign and its possible extensions. We expect to recover lags for ˜35-45 per cent of the quasars. AGN with shorter lags and greater variability are more likely to yield a lag measurement, and objects with lags ≲6 months or ˜1 yr are expected to be recovered the most accurately. The baseline OzDES reverberation mapping campaign is predicted to produce an unbiased measurement of the R-L relationship parameters for H β, Mg II λ2798, and C IV λ1549. Extending the baseline survey by either increasing the spectroscopic cadence, extending the survey season, or improving the emission-line flux measurement accuracy will significantly improve the R-L parameter constraints for all broad emission lines.

  4. Simulations of the OzDES AGN reverberation mapping project

    SciTech Connect

    King, Anthea L.; Martini, Paul; Davis, Tamara M.; Denney, K. D.; Kochanek, C. S.; Peterson, Bradley M.; Skielboe, Andreas; Vestergaard, Marianne; Huff, Eric; Watson, Darach; Banerji, Manda; McMahon, Richard; Sharp, Rob; Lidman, C.

    2015-08-26

    As part of the Australian spectroscopic dark energy survey (OzDES) we are carrying out a large-scale reverberation mapping study of ~500 quasars over five years in the 30 deg2 area of the Dark Energy Survey (DES) supernova fields. These quasars have redshifts ranging up to 4 and have apparent AB magnitudes between 16.8 mag < r < 22.5 mag. The aim of the survey is to measure time lags between fluctuations in the quasar continuum and broad emission-line fluxes of individual objects in order to measure black hole masses for a broad range of active galactic nuclei (AGN) and constrain the radius–luminosity (R–L) relationship. Here we investigate the expected efficiency of the OzDES reverberation mapping campaign and its possible extensions. We expect to recover lags for ~35–45 % of the quasars. AGN with shorter lags and greater variability are more likely to yield a lag measurement, and objects with lags ≲6 months or ~1 yr are expected to be recovered the most accurately. The baseline OzDES reverberation mapping campaign is predicted to produce an unbiased measurement of the R–L relationship parameters for Hβ, MgIIλ2798, and C IVλ1549. As a result, extending the baseline survey by either increasing the spectroscopic cadence, extending the survey season, or improving the emission-line flux measurement accuracy will significantly improve the R–L parameter constraints for all broad emission lines.

  5. 'Harder when Brighter' Spectral Variability in Low-Luminosity AGN

    NASA Astrophysics Data System (ADS)

    Connolly, S.; McHardy, I.; Skipper, C.; Dwelly, T.

    2015-07-01

    We present X-ray spectral variability of four low accretion rate AGN - M81, NGC 1097, NGC 1052 and NGC 3998 - as observed by Swift and RXTE. All four objects were selected due to having spectra which hardened with increasing count rate, converse to the `softer when brighter' behaviour normally observed in AGN with higher accretion rates. The spectra were summed in flux bins and fitted with a variety of models. A simple absorbed power law model was found to fit the spectra of M81, NGC 1097 and NGC 3998 well, whilst NGC 1052 required a partially covered power law model. In all four cases, the most likely main source of spectral variability is found to be luminosity-dependent changes in the photon index of the power law component. An anticorrelation between the photon index and the count rate is found in all of the sources. The anticorrelation is likely to be caused by accretion via a radiatively-inefficient accretion flow, expected in low-Eddington ratio systems such as these, and/or due to the presence of a jet. This behaviour is similar to that seen in the `hard state' of X-ray binaries, implying that these LLAGN are in a similar state.

  6. Dramatic long-term X-ray variability in AGNs

    NASA Astrophysics Data System (ADS)

    Moran, Edward C.

    2016-04-01

    Dramatic X-ray and optical variability on ˜ 10 year timescales has been discovered recently in a handful of quasars, which may provide important new insight into the issue of how luminous AGNs are fueled. We have assembled a new sample of extremely variable X-ray sources from archival Einstein and ROSAT data that could increase substantially the number of such objects known. The sources in our sample varied in X-ray flux by at least a factor of 7-8 over a 10-year span, and most exhibited significantly larger variability amplitudes (10 to over 100). We present the details of how our sample was assembled and preliminary results regarding the identifications, properties, and X-ray histories of the objects. Although a heterogeneous population is expected, some sources in the sample are associated with broad-line AGNs, including a radio-quiet quasar at z = 1.3 that decreased in X-ray luminosity by a factor of 40.

  7. Using gravitationally lensed images to investigate the intrinsic AGN variability

    NASA Astrophysics Data System (ADS)

    Martí-Vidal, I.; Muller, S.

    2016-05-01

    We discuss about how the relative flux densities among the images of gravitationally-lensed active galactic nuclei (AGN), can be used to study the intrinsic AGN variability with high accuracy. Multi-frequency monitoring observations of resolved gravitational lenses can allow us to detect signals of very weak variability and also provide information about the jet opacity and structure. As an example, we investigate the variability of the flux-density ratio between the two lensed images of the blazar B 0218+357, using dual-frequency cm-wave observations. Similar to our previously reported submm-wave observations of the lensed blazar PKS 1830-211, we observe a clear chromatic variability, starting short before an increase in the flux-density of the blazar. The evolution of the flux-density ratios between the blazar images shows a more clear and rich structure than that of the mere lightcurves of each individual image. The accuracy in the ratio measurements is allowing us to see variability episodes in the blazar that are weaker than the natural scatter in the absolute flux-density measurements. A simple opacity model in the jet is used to consistently explain the difference between the flux-density-ratio evolution at the two frequencies.

  8. The AGN-driven shock in NGC 4472

    NASA Astrophysics Data System (ADS)

    Gendron-Marsolais, Marie-Lou; Kraft, Ralph P.; Bogdan, Akos; Forman, William R.; Hlavacek-Larrondo, Julie; Jones, Christine; Nulsen, Paul; Randall, Scott W.; Roediger, Elke

    2016-04-01

    Chandra observations of most cool core clusters of galaxies have revealed large cavities where the inflation of the jet-driven radio bubbles displace the cluster gas. In a few cases, outburst shocks, likely driven by cavity inflation, are detected in the ambient gas. AGN-driven shocks may be key to balancing the radiative losses as shocks will increase the entropy of, and thereby heat, the diffuse gas. We will present initial results on deep Chandra observations of the nearby (D=17 Mpc) early-type massive elliptical galaxy NGC 4472, the most optically luminous galaxy in the local Universe, lying on the outskirts of the Virgo cluster. The X-ray observations show clear cavities in the X-ray emission at the position of the radio lobes, and rings of enhanced X-ray emission just beyond the lobes. We will present results from our analysis to determine whether the lobes are inflating supersonically or are rising buoyantly. We will compare the energy and power of this AGN outburst with previous powerful radio outbursts in clusters and groups to determine whether this outburst lies on the same scaling relations or whether it represents a new category of outburst.

  9. The softest Einstein AGN (active galactic nuclei)

    SciTech Connect

    Cordova, F.A.; Kartje, J.; Mason, K.O.; Mittaz, J.P.D.; Chicago Univ., IL; University Coll., London . Mullard Space Science Lab.)

    1989-01-01

    We have undertaken a coarse spectral study to find the softest sources detected with the Imaging Proportional Counter (IPC) on the Einstein Observatory. Of the nearly 7700 IPC sources, 226 have color ratios that make them candidate ultrasoft'' sources; of these, 83 have small enough errors that we can say with confidence that they have a spectral component similar to those of the white dwarfs Sirius and HZ 43, nearby stars such as {alpha} Cen and Procyon, and typical polar'' cataclysmic variables. By means of catalog searches and ground-based optical and radio observations we have thus far identified 96 of the 226 candidate soft sources; 37 of them are active galactic nuclei (AGN). In the more selective subset of 83 sources, 47 have been identified, 12 of them with AGN. The list of 47 identifications is given in Cordova et al. For one QSO in our sample, E0132.8--411, we are able to fit the pulse-height data to a power-law model and obtain a best fit for the energy spectral index of 2. 2{sub {minus}0.4}{sup +0.6}. For the remainder of the AGN in the higher confidence sample we are able to infer on the basis of their x-ray colors that they have a similar spectral component. Two-thirds of the AGN are detected below 0.5 keV only, while the remainder evidence a flatter spectral component in addition to the ultra-soft component. 14 refs., 5 figs.

  10. AGN Black Hole Masses from Reverberation Mapping

    NASA Technical Reports Server (NTRS)

    Peterson, B. M.

    2004-01-01

    Emission-line variability data on bright AGNs indicates that the central objects in these sources have masses in the million to few-hundred million solar mass range. The time-delayed response of the emission lines to continuum variations can be used to infer the size of the line-emitting region via light travel-time arguments. By combining these sizes with the Doppler widths of the variable part of the emission lines, a virial mass estimate can be obtained. For three especially well-studied sources, NGC 5548, NGC 7469, and 3C 390.3, data on multiple emission lines can be used to test the virial hypothesis. In each of these cases, the response time of the various emission lines is anticorrelated with the line width, with the dependence as expected for gravitationally bound motion of the line-emitting clouds, i.e., that the square of the Doppler line width is inversely proportional to the emission-line time delay. Virial masses based on the Balmer lines have now been measured for about three dozen AGNs. Systematic effects currently limit the accuracy of these masses to a factor of several, but characteristics of the radius-luminosity and mass-luminosity relationships for AGNs are beginning to emerge.

  11. Do stars contribute to AGN fuelling?

    NASA Astrophysics Data System (ADS)

    Davies, Richard

    2011-11-01

    While the existence of a starburst-AGN connection is undisputed, there is no consensus on whether AGN fuelling is synchronous with star formation or follows it during a post-starburst phase. I begin by presenting an overview of some of the observational evidence and theoretical models favouring each perspective. I then focus on recent high resolution observations that are able to probe the central tens of parsecs where star formation might influence AGN activity. I show that both the starburst phase and the physical state of the dense molecular gas imply that stellar feedback plays a critical role in first hindering and then helping accretion. I argue that it is only after the early turbulent phases of a starburst that gas from slow stellar winds can accrete efficiently to smaller scales. And I outline other contexts where similar processes appear to be at work. I finish by showing how the properties of the obscuring torus are directly coupled to this star formation, and that we should be thinking of the torus as a complex dynamical entity.

  12. Diesel exhaust but not ozone increases fraction of exhaled nitric oxide in a randomized controlled experimental exposure study of healthy human subjects

    PubMed Central

    2013-01-01

    Background Fraction of exhaled nitric oxide (FENO) is a promising non-invasive index of airway inflammation that may be used to assess respiratory effects of air pollution. We evaluated FENO as a measure of airway inflammation after controlled exposure to diesel exhaust or ozone. Methods Healthy volunteers were exposed to either diesel exhaust (particle concentration 300 μg/m3) and filtered air for one hour, or ozone (300 ppb) and filtered air for 75 minutes. FENO was measured in duplicate at expiratory flow rates of 10, 50, 100 and 270 mL/s before, 6 and 24 hours after each exposure. Results Exposure to diesel exhaust increased FENO at 6 hours compared with air at expiratory flow rates of 10 mL/s (p = 0.01) and at 50 mL/s (p = 0.011), but FENO did not differ significantly at higher flow rates. Increases in FENO following diesel exhaust were attenuated at 24 hours. Ozone did not affect FENO at any flow rate or time point. Conclusions Exposure to diesel exhaust, but not ozone, increased FENO concentrations in healthy subjects. Differences in the induction of airway inflammation may explain divergent responses to diesel exhaust and ozone, with implications for the use of FENO as an index of exposure to air pollution. PMID:23602059

  13. The Keck OSIRIS Nearby AGN (KONA) Survey: AGN Fueling and Feedback

    NASA Astrophysics Data System (ADS)

    Hicks, Erin K. S.; Müller-Sánchez, Francisco; Malkan, Matthew A.; Yu, Po-Chieh

    In an effort to better constrain the relevant physical processes dictating the co-evolution of supermassive black holes and the galaxies in which they reside we turn to local Seyfert AGN. It is only with these local AGN that we can reach the spatial resolution needed to adequately characterize the inflow and outflow mechanisms thought to be the driving forces in establishing the relationship between black holes and their host galaxies at higher redshift. We present the first results from the KONA (Keck OSIRIS Nearby AGN) survey, which takes advantage of the integral field unit OSIRIS plus laser and natural guide star adaptive optics to probe down to scales of 5-30 parsecs in a sample of 40 local Seyfert galaxies. With these K-band data we measure the two-dimensional distribution and kinematics of the nuclear stars, molecular gas, and ionized gas within the central few hundred parsecs.

  14. Intermediate inclinations of type 2 Coronal-Line Forest AGN

    NASA Astrophysics Data System (ADS)

    Rose, Marvin; Elvis, Martin; Crenshaw, Michael; Glidden, Ana

    2015-07-01

    Coronal-Line Forest Active Galactic Nuclei (CLiF AGN) are remarkable in the sense that they have a rich spectrum of dozens of coronal emission lines (e.g. [Fe VII], [Fe X] and [Ne V]) in their spectra. Rose, Elvis & Tadhunter suggest that the inner obscuring torus wall is the most likely location of the coronal line region in CLiF AGN, and the unusual strength of the forbidden high-ionization lines is due to a specific AGN-torus inclination angle. Here, we test this suggestion using mid-IR colours (4.6-22 μm) from the Wide-Field Infrared Survey Explorer for the CLiF AGN. We use the Fischer et al. result that showed that as the AGN-torus inclination becomes more face on, the Spitzer 5.5-30 μm colours become bluer. We show that the [W2-W4] colours for the CLiF AGN (<[W2-W4]> = 5.92 ± 0.12) are intermediate between Sloan Digital Sky Survey (SDSS) type 1 (<[W2-W4]> = 5.22 ± 0.01) and type 2 AGN (<[W2-W4]> = 6.35 ± 0.03). This implies that the AGN-torus inclinations for the CLiF AGN are indeed intermediate, supporting the work of Rose, Elvis & Tadhunter. The confirmed relation between CLiF AGN and their viewing angle shows that CLiF AGN may be useful for our understanding of AGN unification.

  15. PRIMUS: The Relationship between Star Formation and AGN Accretion

    NASA Astrophysics Data System (ADS)

    Azadi, Mojegan; Aird, James; Coil, Alison L.; Moustakas, John; Mendez, Alexander J.; Blanton, Michael R.; Cool, Richard J.; Eisenstein, Daniel J.; Wong, Kenneth C.; Zhu, Guangtun

    2015-06-01

    We study the evidence for a connection between active galactic nuclei (AGNs) fueling and star formation by investigating the relationship between the X-ray luminosities of AGNs and the star formation rates (SFRs) of their host galaxies. We identify a sample of 309 AGNs with {10}41\\lt {L}X\\lt {10}44 erg s-1 at 0.2\\lt z\\lt 1.2 in the PRIMUS redshift survey. We find AGNs in galaxies with a wide range of SFR at a given LX. We do not find a significant correlation between SFR and the observed instantaneous LX for star-forming AGN host galaxies. However, there is a weak but significant correlation between the mean LX and SFR of detected AGNs in star-forming galaxies, which likely reflects that LX varies on shorter timescales than SFR. We find no correlation between stellar mass and LX within the AGN population. Within both populations of star-forming and quiescent galaxies, we find a similar power-law distribution in the probability of hosting an AGN as a function of specific accretion rate. Furthermore, at a given stellar mass, we find a star-forming galaxy ˜2-3 more likely than a quiescent galaxy to host an AGN of a given specific accretion rate. The probability of a galaxy hosting an AGN is constant across the main sequence of star formation. These results indicate that there is an underlying connection between star formation and the presence of AGNs, but AGNs are often hosted by quiescent galaxies.

  16. Ultra-fast outflows (aka UFOs) from AGNs and QSOs

    NASA Astrophysics Data System (ADS)

    Cappi, M.; Tombesi, F.; Giustini, M.

    During the last decade, strong observational evidence has been accumulated for the existence of massive, high velocity winds/outflows (aka Ultra Fast Outflows, UFOs) in nearby AGNs and in more distant quasars. Here we briefly review some of the most recent developments in this field and discuss the relevance of UFOs for both understanding the physics of accretion disk winds in AGNs, and for quantifying the global amount of AGN feedback on the surrounding medium.

  17. Unification of Low Luminosity AGN and Hard State X-ray Binaries

    NASA Astrophysics Data System (ADS)

    Connolly, S.

    2015-09-01

    We present X-ray spectral variability of four low accretion rate and low luminosity AGN (LLAGN)- M81, NGC 1097, NGC 1052 and NGC 3998 - as observed by Swift and RXTE. All four objects were selected due to having spectra which hardened with increasing count rate, converse to the 'softer when brighter' behaviour normally observed in AGN with higher accretion rates. The spectra were summed in flux bins and fitted with a variety of models. A simple absorbed power law model was found to fit the spectra of M81, NGC 1097 and NGC 3998 well, whilst NGC 1052 required a partially covered power law model. In all four cases, the most likely cause of spectral variability is found to be hardening of the photon index of the power law component with increasing luminosity. Such a correlation has been seen previously within samples of low accretion rate AGN but in only one case has it been seen within observations of a single AGN. Here we show that such behaviour may be very common in LLAGN. A similar anticorrelation is found in X-ray binary systems in the 'hard state', at low accretion rates similar to those of the LLAGN discussed here. Our observations thus imply that LLAGN are the active galaxy equivalent of hard state X-ray binaries.

  18. Shaping the X-ray spectrum of galaxy clusters with AGN feedback and turbulence

    NASA Astrophysics Data System (ADS)

    Gaspari, M.

    2015-07-01

    The hot plasma filling galaxy clusters emits copious X-ray radiation. The classic unheated and unperturbed cooling flow model predicts dramatic cooling rates and an isobaric X-ray spectrum with constant differential luminosity distribution. The observed cores of clusters (and groups) show instead a strong deficit of soft X-ray emission: dLx/dT ∝ (T/Thot)α = 2 ± 1. Using 3D hydrodynamic simulations, we show that such deficit arises from the tight self-regulation between thermal instability condensation and AGN outflow injection: condensing clouds boost the AGN outflows, which quench cooling as they thermalize through the core. The resultant average distribution slope is α ≃ 2, oscillating within the observed 1 < α < 3. In the absence of thermal instability, the X-ray spectrum remains isothermal (α ≳ 8), while unopposed cooling drives a too shallow slope, α < 1. AGN outflows deposit their energy inside-out, releasing more heat in the inner cooler phase; radially distributed heating alone induces a declining spectrum, 1 < α < 2. Turbulence further steepens the spectrum and increases the scatter: the turbulent Mach number in the hot phase is subsonic, while it becomes transonic in the cooler phase, making perturbations to depart from the isobaric mode. Such increase in dln P/dln T leads to α ≈ 3. Self-regulated AGN outflow feedback can address the soft X-ray problem through the interplay of heating and turbulence.

  19. The Prevalence of Gas Outflows in Type 2 AGNs. II. 3D Biconical Outflow Models

    NASA Astrophysics Data System (ADS)

    Bae, Hyun-Jin; Woo, Jong-Hak

    2016-09-01

    We present 3D models of biconical outflows combined with a thin dust plane for investigating the physical properties of the ionized gas outflows and their effect on the observed gas kinematics in type 2 active galactic nuclei (AGNs). Using a set of input parameters, we construct a number of models in 3D and calculate the spatially integrated velocity and velocity dispersion for each model. We find that three primary parameters, i.e., intrinsic velocity, bicone inclination, and the amount of dust extinction, mainly determine the simulated velocity and velocity dispersion. Velocity dispersion increases as the intrinsic velocity or the bicone inclination increases, while velocity (i.e., velocity shifts with respect to systemic velocity) increases as the amount of dust extinction increases. Simulated emission-line profiles well reproduce the observed [O iii] line profiles, e.g., narrow core and broad wing components. By comparing model grids and Monte Carlo simulations with the observed [O iii] velocity–velocity dispersion distribution of ∼39,000 type 2 AGNs, we constrain the intrinsic velocity of gas outflows ranging from ∼500 to ∼1000 km s‑1 for the majority of AGNs, and up to ∼1500–2000 km s‑1 for extreme cases. The Monte Carlo simulations show that the number ratio of AGNs with negative [O iii] velocity to AGNs with positive [O iii] velocity correlates with the outflow opening angle, suggesting that outflows with higher intrinsic velocity tend to have wider opening angles. These results demonstrate the potential of our 3D models for studying the physical properties of gas outflows, applicable to various observations, including spatially integrated and resolved gas kinematics.

  20. Hot Dust Obscured Galaxies with Excess Blue Light: Dual AGN or Single AGN Under Extreme Conditions?

    NASA Astrophysics Data System (ADS)

    Assef, R. J.; Walton, D. J.; Brightman, M.; Stern, D.; Alexander, D.; Bauer, F.; Blain, A. W.; Diaz-Santos, T.; Eisenhardt, P. R. M.; Finkelstein, S. L.; Hickox, R. C.; Tsai, C.-W.; Wu, J. W.

    2016-03-01

    Hot dust-obscured galaxies (Hot DOGs) are a population of hyper-luminous infrared galaxies identified by the Wide-field Infrared Survey Explorer (WISE) mission from their very red mid-IR colors, and characterized by hot dust temperatures (T > 60 K). Several studies have shown clear evidence that the IR emission in these objects is powered by a highly dust-obscured active galactic nucleus (AGN) that shows close to Compton-thick absorption at X-ray wavelengths. Thanks to the high AGN obscuration, the host galaxy is easily observable, and has UV/optical colors usually consistent with those of a normal galaxy. Here we discuss a sub-population of eight Hot DOGs that show enhanced rest-frame UV/optical emission. We discuss three scenarios that might explain the excess UV emission: (i) unobscured light leaked from the AGN by reflection over the dust or by partial coverage of the accretion disk; (ii) a second unobscured AGN in the system; or (iii) a luminous young starburst. X-ray observations can help discriminate between these scenarios. We study in detail the blue excess Hot DOG WISE J020446.13-050640.8, which was serendipitously observed by Chandra/ACIS-I for 174.5 ks. The X-ray spectrum is consistent with a single, hyper-luminous, highly absorbed AGN, and is strongly inconsistent with the presence of a secondary unobscured AGN. Based on this, we argue that the excess blue emission in this object is most likely either due to reflection or a co-eval starburst. We favor the reflection scenario as the unobscured star formation rate needed to power the UV/optical emission would be ≳1000 M⊙ yr-1. Deep polarimetry observations could confirm the reflection hypothesis.

  1. A comparative study of AGN feedback algorithms

    NASA Astrophysics Data System (ADS)

    Wurster, J.; Thacker, R. J.

    2013-05-01

    Modelling active galactic nuclei (AGN) feedback in numerical simulations is both technically and theoretically challenging, with numerous approaches having been published in the literature. We present a study of five distinct approaches to modelling AGN feedback within gravitohydrodynamic simulations of major mergers of Milky Way-sized galaxies. To constrain differences to only be between AGN feedback models, all simulations start from the same initial conditions and use the same star formation algorithm. Most AGN feedback algorithms have five key aspects: the black hole accretion rate, energy feedback rate and method, particle accretion algorithm, black hole advection algorithm and black hole merger algorithm. All models follow different accretion histories, and in some cases, accretion rates differ by up to three orders of magnitude at any given time. We consider models with either thermal or kinetic feedback, with the associated energy deposited locally around the black hole. Each feedback algorithm modifies the region around the black hole to different extents, yielding gas densities and temperatures within r ˜ 200 pc that differ by up to six orders of magnitude at any given time. The particle accretion algorithms usually maintain good agreement between the total mass accreted by dot{M} dt and the total mass of gas particles removed from the simulation, although not all algorithms guarantee this to be true. The black hole advection algorithms dampen inappropriate dragging of the black holes by two-body interactions. Advecting the black hole a limited distance based upon local mass distributions has many desirably properties, such as avoiding large artificial jumps and allowing the possibility of the black hole remaining in a gas void. Lastly, two black holes instantly merge when given criteria are met, and we find a range of merger times for different criteria. This is important since the AGN feedback rate changes across the merger in a way that is dependent

  2. AGN Variability Surveys: DASCH from BATSS to EXIST

    NASA Astrophysics Data System (ADS)

    Grindlay, J. E.

    2007-10-01

    Active galactic nuclei (AGN) are variable on a wide range of timescales. Combined with their redshifts and thus luminosity, variability was of course instrumental in their initial identification with accretion onto supermassive black holes. Previous broad-band (both spectral and temporal) variability surveys of AGN are limited in their temporal and spectral bandwidth, despite their promise for probing the central engine and black hole mass. We provide a brief summary of three new AGN variability surveys, two (BATSS and DASCH) about to begin and the third (EXIST) possible within the next decade, which will open new windows on the physics and fundamental properties of AGN.

  3. Investigating The AGN Population In Cluster Environments Across Different Wavelengths

    NASA Astrophysics Data System (ADS)

    Byler, Eleanor; Norman, D.

    2011-01-01

    Currently, there is no complete picture of AGN formation and evolution in galaxy clusters. A general understanding of the AGN population has been impeded by cluster and selection biases and recent studies have shown that there is a large population of obscured or optically unremarkable AGN in galaxy clusters. We used SDSS data to look at the AGN distribution in 12 clusters over a range of redshifts (z = 0.16 - 0.35) and compared the optical and X-ray AGN content with that of six `blank’ fields. We found that on average the cluster fields had a small optical AGN excess as compared to blank fields. The AGN population and distribution was also compared by cluster morphology, and non-virialized clusters were found to have a higher X-ray and optical AGN content than virialized clusters. We also compare our optical AGN to Gilmour et al.'s (2009) X-ray survey to compare assumptions made about cluster membership. Byler was supported by the NOAO/KPNO Research Experiences for Undergraduates (REU) Program, which is funded by the National Science Foundation Research Experiences for Undergraduates Program and the Department of Defense ASSURE program through Scientific Program Order No. 13 (AST-0754223) of the Cooperative Agreement No. AST-0132798 between the Association of Universities for Research in Astronomy (AURA) and the NSF.

  4. Are the hosts of VLBI-selected radio-AGN different to those of radio-loud AGN?

    NASA Astrophysics Data System (ADS)

    Rees, G. A.; Norris, R. P.; Spitler, L. R.; Herrera-Ruiz, N.; Middelberg, E.

    2016-05-01

    Recent studies have found that radio-AGN selected by radio-loudness show little difference in terms of their host galaxy properties when compared to non-AGN galaxies of similar stellar mass and redshift. Using new 1.4 GHz very long baseline interferometry (VLBI) observations of the Cosmological Evolution Survey field, we find that approximately 49 ± 8 per cent of high-mass (M > 1010.5 M⊙), high-luminosity (L1.4 > 1024 W Hz-1) radio-AGN possess a VLBI-detected counterpart. These objects show no discernible bias towards specific stellar masses, redshifts or host properties other than what is shown by the radio-AGN population in general. Radio-AGN that are detected in VLBI observations are not special, but form a representative sample of the radio-loud AGN population.

  5. The X-ray spectral properties of the AGN population in the XMM-Newton bright serendipitous survey

    NASA Astrophysics Data System (ADS)

    Corral, A.; Della Ceca, R.; Caccianiga, A.; Severgnini, P.; Brunner, H.; Carrera, F. J.; Page, M. J.; Schwope, A. D.

    2011-06-01

    the 3σ confidence level. Finally, by dividing the type 1 AGN sample into high- and low-luminosity sources, we marginally detect a decrease in the narrow Fe Kα line EW and in the amount of reflection as the luminosity increases, the "so-called" Iwasawa-Taniguchi effect. Appendix and Tables 2, 3 are available in electronic form at http://www.aanda.org

  6. A simple way to improve AGN feedback prescription in SPH simulations

    NASA Astrophysics Data System (ADS)

    Zubovas, Kastytis; Bourne, Martin A.; Nayakshin, Sergei

    2016-03-01

    Active galactic nuclei (AGN) feedback is an important ingredient in galaxy evolution, however its treatment in numerical simulations is necessarily approximate, requiring subgrid prescriptions due to the dynamical range involved in the calculations. We present a suite of smoothed particle hydrodynamics simulations designed to showcase the importance of the choice of a particular subgrid prescription for AGN feedback. We concentrate on two approaches to treating wide-angle AGN outflows: thermal feedback, where thermal and kinetic energy is injected into the gas surrounding the supermassive black hole (SMBH) particle, and virtual particle feedback, where energy is carried by tracer particles radially away from the AGN. We show that the latter model produces a far more complex structure around the SMBH, which we argue is a more physically correct outcome. We suggest a simple improvement to the thermal feedback model - injecting the energy into a cone, rather than spherically symmetrically - and show that this markedly improves the agreement between the two prescriptions, without requiring any noticeable increase in the computational cost of the simulation.

  7. Galaxies, AGN, and Environment at z=1: IRAC observations of DEEP2

    NASA Astrophysics Data System (ADS)

    Jones, Christine; Hickox, Ryan; Bundy, Kevin; Coil, Alison; Cool, Richard; Cooper, Michael; Croton, Darren; Davis, Marc; Eisenhardt, Peter; Eisenstein, Daniel; Faber, Sandy; Forman, William; Koo, David; Murray, Stephen; Papovich, Casey; Stern, Daniel; Weiner, Benjamin; Willmer, Christopher; Willner, Steven

    2008-03-01

    The Spitzer view of the z=1 Universe is spectroscopy starved. Only 5 sq. deg. of the sky have been surveyed with very deep (24th mag) spectroscopy that probes z>1 galaxies, and only about half of this area has been observed with Spitzer. Cosmic variance is severe even at z>1 and limits our ability to measure the evolution of galaxies and AGN at these epochs. DEEP2 is the premier z>1 wide-field survey, but only 1.5 sq. deg. of it has Spitzer coverage. Here we propose to more than double the overlap between Spitzer and DEEP2, with IRAC coverage of two fields that contain ~16,000 high-quality Keck spectra of galaxies at 0.7AGN, across a wide range of environments, as a function of redshift. IRAC data will provide robust stellar masses (especially for blue galaxies) and allow us to identify at least 50% more AGN than are found in the X-ray and optical bands alone, revealing a unbiased view of the AGN population to high levels of obscuration. We will use the dense DEEP2 sampling to determine small-scale environments and clustering of galaxies and AGN as a function of stellar mass, color and luminosity. We will also be able to compare IRAC-based stellar masses with DEEP2 dynamical masses. The proposed observations will increase the overlap between IRAC and DEEP2 by a factor of 2.3. This will greatly increase the statistical power of the survey, reduce cosmic variance, and allow measurements of environment and clustering in multiple bins of AGN luminosity or stellar mass, needed to constrain galaxy and AGN evolution models. DEEP2 is the only survey that provides high-quality galaxy spectra and precise redshifts over a large volume at high redshift; these observations will therefore produce a lasting legacy dataset for

  8. Feedback in the local Universe: Relation between star formation and AGN activity in early type galaxies

    NASA Astrophysics Data System (ADS)

    Vaddi, Sravani; O'Dea, Christopher; Baum, Stefi; Jones, Christine; Forman, William; Whitmore, Samantha; Ahmed, Rabeea; Pierce, Katherine; Leary, Sara

    2015-08-01

    Aim: We address the relation between star formation and AGN activity in a large sample of nearby early type (E and S0) galaxies. The redshift range of the galaxies is 0.0002AGN is believed to play an important role in regulating star formation and thus the process of galaxy evolution and formation. Evidence of AGN feedback is found in massive galaxies in galaxy clusters. However, how common AGN feedback is in the local universe and in small scale systems is still not evident.Methods: To answer this question, we carried out a multiple wavelength study of a sample of 231 early type galaxies which were selected to have an apparent K-band magnitude brighter than 13.5 and whose positions correlate with Chandra ACIS-I and ACIS-S sources. The galaxies in the sample are unbiased regarding their star formation and radio source properties. Using the archival observations at radio, IR and UV from VLA, WISE and GALEX respectively, we obtained the radio power, estimate FUV star formation rate (SFR) and other galaxy properties to study AGN activity and ongoing star formation.Results: The relationship between radio power and stellar mass shows that there is an upper envelope of radio power that is a steep function of stellar luminosity. This suggests that less massive galaxies have low radio power while massive galaxies are capable of hosting powerful radio sources. The Radio-MIR relation shows that galaxies with P>=1022 WHz-1 are potential candidates for being AGN. About ~ 7% of the sample show evidence of ongoing star formation with SFR ranging from 10-3 to 1 M⊙yr-1. These are also less massive and radio faint suggesting the absence of active accretion. There is nearly equal fraction of star forming galaxies in radio faint (P<1022 WHz-1) and radio bright galaxies (P>=1022 WHz-1) . Only ~ 5% of the galaxies in our sample have P>=1022 WHz-1 and most of them do not show evidence of bright accretion disks. We see a weak correlation and a dispersion of

  9. Overnight storage of blood in ACD tubes at 4{degrees}C increases NK cell fraction in peripheral blood mononuclear cells.

    PubMed

    Kim, Da-Woon; Jang, Youn-Young; Shin, Myung-Geun; Shin, Jong-Hee; Suh, Soon-Pal; Ryang, Dong-Wook; Yoon, Meesun; Lee, Je-Jung; Kim, Sang-Ki; Cho, Duck

    2013-01-01

    A considerable variabilility in the effects of sample handling on NK cytotoxicity has been observed. Using flow cytometry, NK cytotoxicity assays and lymphocyte subset analysis of Ficoll-Hypaque-separated peripheral blood mononuclear cells (PBMCs) isolated from whole blood stored under various conditions were performed. The NK cytotoxicity of samples in heparin tubes stored overnight at 4 and 22°C, as well as at 22°C in acid citrate dextrose (ACD) tubes, was lower than that of a fresh sample. However, the NK cytotoxicity of samples in an ACD tube stored at 4°C was similar to that of a fresh sample. Based on lymphocyte subset analysis, samples in an ACD tube stored at 4°C showed a lower percentage of CD3+ T cells and a higher percentage of CD16/56+ NK cells compared to samples stored under other conditions. The NK cytotoxicity of fresh samples and samples in ACD tubes stored in a Styrofoam cooler box did not differ significantly; however, the differences were inconsistent. Overnight storage of peripheral blood in ACD tubes at 4°C is optimum for retention of NK cytotoxicity, the level of which is similar to that of fresh blood. This may be associated with an increased NK-cell fraction in Ficoll-Hypaque-separated PBMCs after overnight storage. PMID:23884220

  10. A polysaccharide fraction from Achillea millefolium increases cytokine secretion and reduces activation of Akt, ERK and NF-κB in THP-1 monocytes.

    PubMed

    Freysdottir, Jona; Logadottir, Oddny T; Omarsdottir, Sesselja S; Vikingsson, Arnor; Hardardottir, Ingibjorg

    2016-06-01

    Achillea millefolium has been used in traditional medicine for a number of ailments, including skin inflammation and wounds. A polysaccharide fraction (Am-25-d) isolated from aqueous extract from A. millefolium had an average molecular weight of 270kDa and a monosaccharide composition of GalA, Gal, Ara, Xyl, Rha in molar ratio of 28:26:23:9:7. THP-1 cells primed with IFN-γ and stimulated with LPS in the presence of Am-25-d secreted more IL-1β, IL-8, IL-10, IL-12p40, IL-23 and TNF-α than THP-1 cells stimulated in the absence of Am-25-d. However, when added to unstimulated cells Am-25-d did not increase secretion of the cytokines examined. Stimulating THP-1 monocytes in the presence of Am-25-d led to decreased nuclear concentrations of NF-κB and phosphorylation of ERK1/2 and Akt kinases compared with that when the cells were stimulated without Am-25-d. These findings indicate that Am-25-d isolated from A. millefolium has immunoenhancing properties that may be mediated via the Akt pathway. PMID:27083352

  11. Long-term Variation of AGNs

    NASA Astrophysics Data System (ADS)

    Fan, J. H.; Xie, G. Z.; Adam, G.; Copin, Y.; Lin, R. G.; Bai, J. M.; Quin, Y. P.

    In this paper we will present the long-term variation in the optical and the infrared bands for some selected AGNs. 1. Some new optical data observed by us have been presented for BL Lacertae (1995-1996) and OJ 287 (1994-1995), and new infrared data are presented for OJ 287 (Nov=2E 1995), which corresponds to the second optical peak (Sillanpaa et al. 1996; Takalo et al. 1996) and during last outburst. 2. For objects with long term observations, the Jurkevich's method has been used to analyses the long-term variation period. It is interesting that the reported periods of AGNs are of the similar value of about 10 years: 3C 345 11.4 years (Webb et al. 1988), 3C 120 15 years (Belokon et al. 1987; Hagen-Thorn et al. 1997), ON 231 13.6 years (Liu et al. 1995), OJ 287 12 years (Sillanpaa et al. 1988; Kidger et al. 1992), PKS 0735+178 14 years (Fan et al. 1997), NGC 4151 15 years (Fan et al. 1998a), BL Lacertae 14.0 years (Fan et al. 1998b). Is the mechanism for the long-term variation the same for different AGNs? 3. The DCF method has been adopted to analysis the variation correlation in the optical and infrared bands for BL Lac object OJ 287, the results show that these two bands are strongly correlated, which suggest that the emission mechanism in the two bands is the same. 4. For the optical and infrared bands, the maximum variations are correlated.

  12. Optical variability of the Kepler AGN

    NASA Astrophysics Data System (ADS)

    Edelson, Rick

    2014-01-01

    Kepler has opened a new era for the study of AGN optical variability, producing light curves with ~0.1% errors (for a ~15th magnitude source), 30 min sampling, >90% duty cycle and durations of years. Thanks to an intensive identification campaign, the number of Seyfert 1s/quasars monitored by Kepler rose from just one (Zw 229-15) in the first year to 37 by the time of May 2013 reaction wheel failure. We measured the optical power spectral density (PSD) functions of these Kepler AGN finding that that on timescales of ~6 hr to 1 month, the PSDs are typically well-fitted with a slop of ~-3, steeper than seen in the X-rays. In a few sources there is also evidence for a flattening at the longest timescales. We also find a broad correlation between rms variability and flux level. These results broadly support the model in which the optical fluctuations are due to vicious instabilities in the accretion disk. I will also present the light curve for W2R1926+42, the only rapidly variable BL Lac object known to be monitored by Kepler. With data covering over a year and sampling rates of 1-30 min, this may be the information-richest AGN light curve ever gathered at any wavelength. The PSD appears to bend from a slope of -2.6 to -1.2 on a ~7 hr timescale, but fits are formally unacceptable. These data indicate that the phenomenon of blazar "microvariability" (sporadic variations on timescales shorter than the ~12 hour window available from the ground) actually results from a combination of rapid, powerful variability interspersed with longer, relatively quiescent periods.

  13. Warm Absorber Diagnostics of AGN Dynamics

    NASA Astrophysics Data System (ADS)

    Kallman, Timothy

    Warm absorbers and related phenomena are observable manifestations of outflows or winds from active galactic nuclei (AGN) that have great potential value. Understanding AGN outflows is important for explaining the mass budgets of the central accreting black hole, and also for understanding feedback and the apparent co-evolution of black holes and their host galaxies. In the X-ray band warm absorbers are observed as photoelectric absorption and resonance line scattering features in the 0.5-10 keV energy band; the UV band also shows resonance line absorption. Warm absorbers are common in low luminosity AGN and they have been extensively studied observationally. They may play an important role in AGN feedback, regulating the net accretion onto the black hole and providing mechanical energy to the surroundings. However, fundamental properties of the warm absorbers are not known: What is the mechanism which drives the outflow?; what is the gas density in the flow and the geometrical distribution of the outflow?; what is the explanation for the apparent relation between warm absorbers and the surprising quasi-relativistic 'ultrafast outflows' (UFOs)? We propose a focused set of model calculations that are aimed at synthesizing observable properties of warm absorber flows and associated quantities. These will be used to explore various scenarios for warm absorber dynamics in order to answer the questions in the previous paragraph. The guiding principle will be to examine as wide a range as possible of warm absorber driving mechanisms, geometry and other properties, but with as careful consideration as possible to physical consistency. We will build on our previous work, which was a systematic campaign for testing important class of scenarios for driving the outflows. We have developed a set of tools that are unique and well suited for dynamical calculations including radiation in this context. We also have state-of-the-art tools for generating synthetic spectra, which are

  14. The Starburst-AGN Connection under the Multiwavelength Limelight

    NASA Astrophysics Data System (ADS)

    Guainazzi, Matteo

    2011-11-01

    Since the discovery of a tight relation between supermassive black hole masses, the bulge luminosity, and the stellar velocity dispersion in the local universe galaxies, mounting experimental evidence has been collected pointing to a connection between nuclear activity and star formation over a wide range of redshifts. Although a growing number of galaxies from different samples exhibit simultaneous starburst and AGN phenomenology, it is still a matter of debate whether this is the smoking gun of a causal relation between them, and, if so, with which trend. Basic issues in modern astrophysics, such as the evolution of galaxies and supermassive black holes, AGN feeding and feedback to the interstellar and intergalactic medium, as well as the role played by the environment on the star formation history are related to this "Starburst-AGN Connection". This Workshop aims at gathering observational and theoretical astronomers so as to answer the following questions: * The "Starburst-AGN Connection": A causal relation? * "Starburst-AGN Connection" at low and high redshift: any evidence for evolution? * Is there a connection between AGN obscuration and star formation? * In which way are the star formation and AGN phenomena affected by the environment? * Do stars contribute to AGN fueling? Multiwavelength observations in the last decade have given a paramount contribution to improve our understanding in this field. The Workshop will build on this panoptic view, and aims at contributing to the scientific case of future ground-based and space large observatories.

  15. The detection and X-ray view of the changing look AGN HE 1136-2304

    NASA Astrophysics Data System (ADS)

    Parker, M. L.; Komossa, S.; Kollatschny, W.; Walton, D. J.; Schartel, N.; Santos-Lleó, M.; Harrison, F. A.; Fabian, A. C.; Zetzl, M.; Grupe, D.; Rodríguez-Pascual, P. M.; Vasudevan, R. V.

    2016-09-01

    We report the detection of high-amplitude X-ray flaring of the AGN HE 1136-2304, which is accompanied by a strong increase in the flux of the broad Balmer lines, changing its Seyfert type from almost type 2 in 1993 down to 1.5 in 2014. HE 1136-2304 was detected by the XMM-Newton slew survey at >10 times the flux it had in the ROSAT all-sky survey, and confirmed with Swift follow-up after increasing in X-ray flux by a factor of ˜30. Optical spectroscopy with SALT shows that the AGN has changed from a Seyfert 1.95 to a Seyfert 1.5 galaxy, with greatly increased broad line emission and an increase in blue continuum AGN flux by a factor of >4. The X-ray spectra from XMM-Newton and NuSTAR reveal moderate intrinsic absorption and a high energy cutoff at ˜100 keV. We consider several different physical scenarios for a flare, such as changes in obscuring material, tidal disruption events, and an increase in the accretion rate. We find that the most likely cause of the increased flux is an increase in the accretion rate, although it could also be due to a change in obscuration.

  16. Propiedades de los AGNs oscurecidos y no oscurecidos

    NASA Astrophysics Data System (ADS)

    Taormina, M.; Bornancini, C.

    In this work we analyze the properties of obscured and unobscured AGNs selected from the "Multiwavelength Survey by Yale-Chile" (MUSYC). The sample of AGNs was selected base on their mid-infrared colors ([3.6], [4.5], [5.8] y [8.0] μm), from images obtained with the Spitzer Space Telescope. We select obscured and unobscured AGN samples using a simple criterion based on the observed optical to mid-IR color with limits R - [4.5] = 3.04 (AB system) and with redshifts in the range 1 < z < 3. Obscured AGNs are intrinsically optically faint in the R band, suggesting that luminous IR- selected AGNs have significant dust extinction. FULL TEXT IN SPANISH

  17. Anchoring the AGN X-ray Luminosity Function

    NASA Astrophysics Data System (ADS)

    Salzer, John

    2003-09-01

    Knowledge of the AGN LF over a range of luminosities and redshifts is crucial to understanding the accretion history of supermassive blackholes. Much of the CXRB has been resolved and spectroscopic follow-up has revealed a mixed bag of object types at moderate to high redshifts. For the deep Chandra survey results to be useful in studying the evolution of the XLF, a representative sample of local AGNs of various types with known X-ray luminosities is needed. The new KPNO International Spectroscopic Survey (KISS) provides the best available sample of H-alpha selected Type 1 and 2 AGNs to serve as the baseline for XLF evolution studies. We propose to observe a volume-limited sample of 28 KISS AGNs to assess their X-ray emission characteristics and establish the local AGN XLF.

  18. A UV to mid-IR study of AGN selection

    SciTech Connect

    Chung, Sun Mi; Kochanek, Christopher S.; Assef, Roberto; Brown, Michael J. I.; Stern, Daniel; Jannuzi, Buell T.; Gonzalez, Anthony H.; Hickox, Ryan C.; Moustakas, John

    2014-07-20

    We classify the spectral energy distributions (SEDs) of 431,038 sources in the 9 deg{sup 2} Boötes field of the NOAO Deep Wide-Field Survey (NDWFS). There are up to 17 bands of data available per source, including ultraviolet (GALEX), optical (NDWFS), near-IR (NEWFIRM), and mid-infrared (IRAC and MIPS) data, as well as spectroscopic redshifts for ∼20,000 objects, primarily from the AGN and Galaxy Evolution Survey. We fit galaxy, active galactic nucleus (AGN), stellar, and brown dwarf templates to the observed SEDs, which yield spectral classes for the Galactic sources and photometric redshifts and galaxy/AGN luminosities for the extragalactic sources. The photometric redshift precision of the galaxy and AGN samples are σ/(1 + z) = 0.040 and σ/(1 + z) = 0.169, respectively, with the worst 5% outliers excluded. On the basis of the χ{sub ν}{sup 2} of the SED fit for each SED model, we are able to distinguish between Galactic and extragalactic sources for sources brighter than I = 23.5 mag. We compare the SED fits for a galaxy-only model and a galaxy-AGN model. Using known X-ray and spectroscopic AGN samples, we confirm that SED fitting can be successfully used as a method to identify large populations of AGNs, including spatially resolved AGNs with significant contributions from the host galaxy and objects with the emission line ratios of 'composite' spectra. We also use our results to compare with the X-ray, mid-IR, optical color, and emission line ratio selection techniques. For an F-ratio threshold of F > 10, we find 16,266 AGN candidates brighter than I = 23.5 mag and a surface density of ∼1900 AGN deg{sup –2}.

  19. A High Fraction of Double-peaked Narrow Emission Lines in Powerful Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Lyu, Yang; Liu, Xin

    2016-08-01

    One percent of redshift z ˜ 0.1 Active Galactic Nuclei (AGNs) show velocity splitting of a few hundred km s-1 in the narrow emission lines in spatially integrated spectra. Such line profiles have been found to arise from the bulk motion of ionized gas clouds associated with galactic-scale outflows, merging pairs of galaxies each harboring a supermassive black hole (SMBH), and/or galactic-scale disk rotation. It remains unclear, however, how the frequency of narrow-line velocity splitting may depend on AGN luminosity. Here we study the correlation between the fraction of Type 2 AGNs with double-peaked narrow emission lines and AGN luminosity as indicated by [O III]λ5007 emission-line luminosity L[O III]. We combine the sample of Liu et al. (2010a) at z ˜ 0.1 with a new sample of 178 Type 2 AGNs with double-peaked [O III] emission lines at z ˜ 0.5. We select the new sample from a parent sample of 2089 Type 2 AGNs from the SDSS-III/Baryon Oscillation Spectroscopic Survey. We find a statistically significant (˜4.2σ) correlation between L[O III] and the fraction of objects that exhibit double-peaked narrow emission lines among all Type 2 AGNs, corrected for selection bias and incompleteness due to [O III] line width, equivalent width, splitting velocity, and/or equivalent width ratio between the two velocity components. Our result suggests that galactic-scale outflows and/or merging pairs of SMBHs are more prevalent in more powerful AGNs, although spatially resolved follow up observations are needed to resolve the origin(s) for the narrow-line velocity splitting for individual AGNs.

  20. Impact of micronised purified flavonoid fraction on increased malondialdehyde and decreased metalloproteinase-2 and metalloproteinase-9 levels in varicocele: outcome of an experimentally induced varicocele.

    PubMed

    Dogan, F; Armagan, A; Oksay, T; Akman, T; Aylak, F; Bas, E

    2014-05-01

    To analyse the levels of an indirect marker of ROS-induced lipid peroxidation [i.e. malondialdehyde (MDA)] in both testes and the levels of matrix metalloproteinase-2 (MMP-2), matrix metalloproteinase-9 (MMP-9) and matrix metalloproteinase inhibitor-1 (TIMP-1) in the left testis after induction of varicocele and investigated the impact of micronised purified flavonoid fraction (MPFF) on these markers. Forty-nine adolescent (6-week-old) male Wistar rats were included in this study. The rats were divided into seven groups as follows:Group-1, control; Group-2, sham; Group-3, left varicocele-induced; Group-4, varicocele + varicocelectomy + MPFF-treated (for 4 weeks); Group-5, varicocele + MPFF-treated (for 8 weeks); Group-6, varicocele-induced and 4 weeks later, MPFF-treated (for 4 weeks); and Group-7, varicocele + varicocelectomy. MDA was measured in the tissues of both testes using the thiobarbituric acid reactivity method. The ELISA method was used for the quantification of MMP-2, MMP-9 and TIMP-1 in the left testicular tissue. The levels of MDA were significantly higher in the varicocele group than in the other groups. The MDA levels in the left testicular tissues of Group-7 were significantly higher than those of Group 4 (P = 0.03). In the varicocele group, the MMP-2 and MMP-9 levels decreased, whereas the levels of TIMP-1 increased. The tissue levels of MMP-2 in Groups 4, 5 and 7 were significantly higher than those in Group 1 (P < 0.05). PMID:23550531

  1. The link between broad emission line fluctuations and non-thermal emission from the inner AGN jet

    NASA Astrophysics Data System (ADS)

    León-Tavares, J.; Chavushyan, V.; Lobanov, A.; Valtaoja, E.; Arshakian, T. G.

    2015-03-01

    AGN reverberate when the broad emission lines respond to changes of the ionizing thermal continuum emission. Reverberation measurements have been commonly used to estimate the size of the broad-line region (BLR) and the mass of the central black hole. However, reverberation mapping studies have been mostly performed on radio-quiet sources where the contribution of the jet can be neglected. In radio-loud AGN, jets and outflows may affect substantially the relation observed between the ionizing continuum and the line emission. To investigate this relation, we have conducted a series of multi-wavelength studies of radio-loud AGN, combining optical spectral line monitoring with regular VLBI observations. Our results suggest that at least a fraction of the broad-line emitting material can be located in a sub-relativistic outflow ionized by non-thermal continuum emission generated in the jet at large distances (> 1 pc) from the central engine of AGN. This finding may have a strong impact on black hole mass estimates based on measured widths of the broad emission lines and on the gamma-ray emission mechanisms.

  2. Extremely efficient Zevatron in rotating AGN magnetospheres

    NASA Astrophysics Data System (ADS)

    Osmanov, Z.; Mahajan, S.; Machabeli, G.; Chkheidze, N.

    2014-12-01

    A novel model of particle acceleration in the magnetospheres of rotating active galactic nuclei (AGN) is constructed. The particle energies may be boosted up to 1021 eV in a two-step mechanism: in the first stage, the Langmuir waves are centrifugally excited and amplified by means of a parametric process that efficiently pumps rotational energy to excite electrostatic fields. In the second stage, the electrostatic energy is transferred to particle kinetic energy via Landau damping made possible by rapid `Langmuir collapse'. The time-scale for parametric pumping of Langmuir waves turns out to be small compared to the kinematic time-scale, indicating high efficiency of the first process. The second process of `Langmuir collapse' - the creation of caverns or low-density regions - also happens rapidly for the characteristic parameters of the AGN magnetosphere. The Langmuir collapse creates appropriate conditions for transferring electric energy to boost up already high particle energies to much higher values. It is further shown that various energy loss mechanism are relatively weak, and do not impose any significant constraints on maximum achievable energies.

  3. Extending the Fermi - Swift Joint AGN Sample

    NASA Astrophysics Data System (ADS)

    Shrader, Chris R.; Macomb, D. J.

    2014-01-01

    The Swift BAT and the Fermi LAT each provide excellent sky coverage and have led to impressive compilations of extragalactic source catalogs. For the most part they sample separate AGN subpopulations - Swift the lower-luminosity and relatively nearby Seyfert galaxies while the Fermi sample is dominated by blazars and does not include any radio-quiet objects. The overlap between these samples is among the radio-loud subset of the Swift sample as has been discussed elsewhere in the literature. The observable properties at these two bands - flux and spectral indices - are not expected to be well correlated as they sample different portions of the synchrotron self-Compton (SSC) spectral energy distribution. In this contribution we consider an extension of the high-latitude Swift sample by relaxing the significance cut to less than 5 standard deviations and consider the overlap of that subsample with the Fermi AGN catalog. While such a threshold is generally inadvisable as it introduces the strong possibility of spurious detections, the objects of the overlapping sample which are detected at high significance in Fermi can be considered as reasonably high-confidence Swift detections. For example, there are 190 Swift sub-5-sigma Swift sources that have significance >2-sigma with Fermi counterparts, whereas we predict only ~5 due to statistical fluctuation. We also investigate any coincident INTEGRAL/IBIS observations to further bolster or diminish candidate Swift detections. We present our correlation analyses and offer interpretation in the context of the blazar sequence.

  4. Simulations of the OzDES AGN reverberation mapping project

    DOE PAGESBeta

    King, Anthea L.; Martini, Paul; Davis, Tamara M.; Denney, K. D.; Kochanek, C. S.; Peterson, Bradley M.; Skielboe, Andreas; Vestergaard, Marianne; Huff, Eric; Watson, Darach; et al

    2015-08-26

    As part of the Australian spectroscopic dark energy survey (OzDES) we are carrying out a large-scale reverberation mapping study of ~500 quasars over five years in the 30 deg2 area of the Dark Energy Survey (DES) supernova fields. These quasars have redshifts ranging up to 4 and have apparent AB magnitudes between 16.8 mag < r < 22.5 mag. The aim of the survey is to measure time lags between fluctuations in the quasar continuum and broad emission-line fluxes of individual objects in order to measure black hole masses for a broad range of active galactic nuclei (AGN) and constrainmore » the radius–luminosity (R–L) relationship. Here we investigate the expected efficiency of the OzDES reverberation mapping campaign and its possible extensions. We expect to recover lags for ~35–45 % of the quasars. AGN with shorter lags and greater variability are more likely to yield a lag measurement, and objects with lags ≲6 months or ~1 yr are expected to be recovered the most accurately. The baseline OzDES reverberation mapping campaign is predicted to produce an unbiased measurement of the R–L relationship parameters for Hβ, MgIIλ2798, and C IVλ1549. As a result, extending the baseline survey by either increasing the spectroscopic cadence, extending the survey season, or improving the emission-line flux measurement accuracy will significantly improve the R–L parameter constraints for all broad emission lines.« less

  5. Structure Function Analysis of AGN Variability using Kepler

    NASA Astrophysics Data System (ADS)

    Kasliwal, Vishal P.; Vogeley, Michael S.; Richards, Gordon T.

    2014-06-01

    We study the variability properties of AGN light-curves observed by the Kepler satellite. AGN optical fluxes are known to exhibit stochastic variations on time-scales of hours, days, months and years. Previous efforts to characterize the stochastic nature of this variability have been hampered by the lack of high-precision space-based measurements of AGN fluxes with regular cadence. Kepler provides light-curves with a S/N ratio of 10-5 for 87 AGN observed over a period of ~ 3 years with a cadence of once every 30 minutes allowing for a detailed examination of the variability process. We probe AGN variability using the Structure Functions of the light-curves of the Kepler AGN. Monte-Carlo simulations of the structure function are used to fit the observed light-curve to models for the Power Spectral Density. We test various models for the form of the PSD including the damped random walk and the powered exponential models. We show that on the shorter time-scales probed by Kepler data, the damped random walk model fails to adequately characterize AGN variability. We find that the PSD may be better modelled by combination of a steep power law of the form 1/f3 on shorter time-scales, and a more shallow power law of the form 1/f2 on the longer time-scales traditionally probed by ground-based variability studies.

  6. Star Formation Quenching and Identifying AGN in Galaxies

    NASA Astrophysics Data System (ADS)

    Mendez, Alexander; Coil, A. L.; Lotz, J. M.; Aird, J.; Diamond-Stanic, A. M.; Moustakas, J.; Salim, S.; Simard, L.; Blanton, M. R.; Eisenstein, D.; Wong, K. C.; Cool, R. J.; Zhu, G.; PRIMUS; AEGIS

    2014-01-01

    I will discuss two observational projects related to galaxy and active galactic nuclei (AGN) evolution at z < 1. First I will present a statistical study of the morphologies of galaxies in which star formation is being shut down or quenched; this has implications for how red, elliptical galaxies are formed. I will discuss the physical processes behind star formation quenching from the morphological transformations that galaxies undergo during this process. Then I will focus on multi-wavelength AGN selection methods and tie together disparate results in the literature. Several IR-AGN selection methods have been developed using Spitzer/IRAC data in order to supplement traditional X-ray AGN selection; I will characterize the uniqueness and complementarity of these methods as a function of both IR and X-ray depth. I will use data from the PRIsm MUlti-object Survey (PRIMUS) to compare the efficiency of IR and X-ray AGN selection and discuss the properties of the AGN and host galaxy populations of each. Finally, I will briefly mention ongoing work to compare the clustering of observed IR and X-ray AGN samples relative to stellar mass-matched galaxy samples.

  7. Compton Thick AGN in the XMM-COSMOS field

    NASA Astrophysics Data System (ADS)

    Lanzuisi, G.; Perna, M.; Delvecchio, I.; Berta, S.; Brusa, M.; Gruppioni, C.; Comastri, A.

    2016-06-01

    I will present results we published in two recent papers (Lanzuisi et al. 2015, A&A 573A 137, Lanzuisi et al. 2015, A&A 578A 120) on the properties of X-ray selected Compton Thick (CT, NH>10^{24} cm^{-2}) AGN, in the XMM-COSMOS survey. We exploited the rich multi-wavelength dataset available in this field, to show that CT AGN tend to harbor smaller, rapidly growing SMBH with respect to unobscured AGN, and have a higher chance of being hosted by star-forming, merging and post-merger systems. We also demonstrated the detectability of even more heavily obscured AGN (NH>10^{25} cm^{-2}), thanks to a truly multi-wavelength approach in the same field, and to the unrivaled XMM sensitivity. The extreme source detected in this way shows strong evidences of ongoing powerful AGN feedback, detected as blue-shifted wings of high ionization optical emission lines such as [NeV] and [FeVII], as well as of the [OIII] emission line. The results obtained from these works point toward a scenario in which highly obscured AGN occupy a peculiar place in the galaxy-AGN co-evolution process, in which both the host and the SMBH rapidly evolve toward the local relations.

  8. Cadence Requirements for AGN Accretion Studies with LSST

    NASA Astrophysics Data System (ADS)

    Moreno, Jackeline; Vogeley, Michael S.; Richards, Gordon T.; Kasliwal, Vishal P.

    2016-01-01

    We test various samplings of mock AGN lightcurves to determine minimum cadence requirements for future technologies like the Large Synoptic Survey Telescope (LSST). AGN lightcurves exhibit stochastic behavior, with variability seen in ground-based optical surveys on timescales from days to years. Significant variability structure on timescales up to a few days was revealed by the high time resolution (~30 minutes) of Kepler Satellite. Now it is apparent that under-sampling by ground based instruments may be leaving out a big chunk of the AGN accretion picture. To probe Kepler AGN, recent studies have investigated the suitability of sophisticated models like CARMA processes to better understand dominant mechanisms driving observed variability across these timescales. By testing models against AGN photometry, we gain insights about accretion physics, intrinsic differences between AGN sub-types, and physical scales pertaining to orbits or casually connected matter flows. We investigate cadence, time window, and regularity requirements that accurately recover parameters of our model lightcurves constructed with a CARMA process and observations such that ground based telescopes can optimally collect data for AGN science.

  9. Studying AGN Feedback with Galactic Outflows in Luminous Obscured Quasar

    NASA Astrophysics Data System (ADS)

    Sun, Ai-Lei

    2016-01-01

    Feedback from Active galactic nuclei (AGN) has been proposed as an important quenching mechanism to suppress star formation in massive galaxies. We investigate the most direct form of AGN feedback - galactic outflows - in the most luminous obscured AGN (L>10^45 erg/s) from the SDSS sample in the nearby universe (z<0.2). Using ALMA and Magellan observations to target molecular and ionized outflows, we find that luminous AGN can impact the dynamics and phase of the galactic medium, and confirm the complex multi-phase and multi-scaled nature of the feedback phenomenon. In particular, we found that most of these luminous AGN hosts ionized outflows. The outflow size, velocity, and energetics correlate with the AGN luminosity, and can be very extended (r > 10 kpc) and fast (v > 1000 km/s) for the most luminous ones. I end with presenting a new technique to find extended ionized outflows using broadband imaging surveys, and to characterize their occurrence rate, morphology, size distribution, and their dependence on the AGN luminosity. This technique will open a new window for feedback studies in the era of large-scale optical imaging surveys, e.g., HSC and then LSST.

  10. Mid-infrared diagnostics to distinguish AGNs from starbursts

    NASA Astrophysics Data System (ADS)

    Laurent, O.; Mirabel, I. F.; Charmandaris, V.; Gallais, P.; Madden, S. C.; Sauvage, M.; Vigroux, L.; Cesarsky, C.

    2000-07-01

    We present new mid-infrared (MIR) diagnostics to distinguish emission of active galactic nuclei (AGN) from that originating in starburst regions. Our method uses empirical spectroscopic criteria based on the fact that MIR emission from star forming or active galaxies arises mostly from HII regions, photo-dissociation regions (PDRs) and AGNs. The analysis of the strength of the 6.2 mu m Unidentified Infrared Band (UIB) and the MIR continuum shows that UIBs are very faint or absent in regions harboring the intense and hard radiation fields of AGNs and pure HII regions, where the UIB carriers could be destroyed. The MIR signature of AGNs is the presence of an important continuum in the 3-10 mu m band which originates from very hot dust heated by the intense AGN radiation field. Using these two distinct spectral properties found in our MIR templates, we build diagnostic diagrams which provide quantitative estimates of the AGN, PDR and HII region contribution in a given MIR spectrum. This new MIR classification can be used to reveal the presence of AGNs highly obscured by large columns of dust. Based on observations made with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, the Netherlands and the United Kingdom) and with the participation of ISAS and NASA.

  11. Compton Thick AGN in the XMM-COSMOS field

    NASA Astrophysics Data System (ADS)

    Lanzuisi, G.; Perna, M.; Delvecchio, I.; Berta, S.; Brusa, M.; Gruppioni, C.; Comastri, A.

    2016-06-01

    I will present results we published in two recent papers (Lanzuisi et al. 2015, A&A 573A 137, Lanzuisi et al. 2015, A≈A 578A 120) on the properties of X-ray selected Compton Thick (CT, NH>10^{24} cm^{-2}) AGN, in the XMM-COSMOS survey. We exploited the rich multi-wavelength dataset available in this field, to show that CT AGN tend to harbor smaller, rapidly growing SMBH with respect to unobscured AGN, and have a higher chance of being hosted by star-forming, merging and post-merger systems. We also demonstrated the detectability of even more heavily obscured AGN (NH>10^{25} cm^{-2}), thanks to a truly multi-wavelength approach in the same field, and to the unrivaled XMM sensitivity. The extreme source detected in this way shows strong evidences of ongoing powerful AGN feedback, detected as blue-shifted wings of high ionization optical emission lines such as [NeV] and [FeVII], as well as of the [OIII] emission line. The results obtained from these works point toward a scenario in which highly obscured AGN occupy a peculiar place in the galaxy-AGN co-evolution process, in which both the host and the SMBH rapidly evolve toward the local relations.

  12. Parsec-Scale Kinematic and Polarization Properties of MOJAVE AGN Jets

    NASA Astrophysics Data System (ADS)

    Lister, Matthew L.

    2013-12-01

    We describe the parsec-scale kinematics and statistical polarization properties of 200 AGN jets based on 15 GHz VLBA data obtained between 1994 Aug 31 and 2011 May 1. Nearly all of the 60 most heavily observed jets show significant changes in their innermost position angle over a 12 to 16 year interval, ranging from 10° to 150° on the sky, corresponding to intrinsic variations of ~ 0.5° to ~ 2°. The BL Lac jets show smaller variations than quasars. Roughly half of the heavily observed jets show systematic position angle trends with time, and 20 show indications of oscillatory behavior. The time spans of the data sets are too short compared to the fitted periods (5 to 12 y), however, to reliably establish periodicity. The rapid changes and large jumps in position angle seen in many cases suggest that the superluminal AGN jet features occupy only a portion of the entire jet cross section, and may be energized portions of thin instability structures within the jet. We have derived vector proper motions for 887 moving features in 200 jets having at least five VLBA epochs. For 557 well-sampled features, there are sufficient data to additionally study possible accelerations. The moving features are generally non-ballistic, with 70% of the well-sampled features showing either significant accelerations or non-radial motions. Inward motions are rare (2% of all features), are slow (< 0.1 mas per y), are more prevalent in BL Lac jets, and are typically found within 1 mas of the unresolved core feature. There is a general trend of increasing apparent speed with distance down the jet for both radio galaxies and BL Lac objects. In most jets, the speeds of the features cluster around a characteristic value, yet there is a considerable dispersion in the distribution. Orientation variations within the jet cannot fully account for the dispersion, implying that the features have a range of Lorentz factor and/or pattern speed. Very slow pattern speed features are rare, comprising

  13. Absorption-line measurements of AGN outflows

    NASA Astrophysics Data System (ADS)

    Fields, Dale L.

    Investigations into the elemental abundances in two nearby active galaxies, the narrow-line Seyfert 1 Markarian 1044 and the Seyfert 1 Markarian 279, are reported. Spectra from three space-based observatories HST, FUSE, and CHANDRA, are used to measure absorption lines in material outflowing from the nucleus. I make multi-wavelength comparisons to better convert the ionic column densities into elemental column densities which can then be used to determine abundances (metallicities). Narrow-line Seyfert 1 galaxies are known to have extreme values of a number of properties compared to active galactic nuclei (AGNs) as a class. In particular, emission-line studies have suggested that NLS1s are unusually metal-rich compared to broad-line AGNs of comparable luminosity. To test these suggestions I perform absorption-line studies on the NLS1 Markarian 1044, a nearby and bright AGN. I use lines of H I, C IV, N V, and O VI to properly make the photoionization correction through the software Cloudy and determine abundances of Carbon, Nitrogen and Oxygen. I find two results. The first is that Markarian 1044 has a bulk metallicity greater than five times solar. The second is that the N/C ratio in Markarian 1044 is consistent with a solar mixture. This is in direct contradiction of extrapolations from local H II regions which state N/ C should scale with bulk metallicity. This implies a different enrichment history in Markarian 1044 than in the Galactic disk. I also report discovery of three new low-redshift Lya forest lines with log N HI >= 12:77 in the spectrum of Markarian 1044. This number is consistent with the 2.6 expected Lya forest lines in the path length to Markarian 1044. I also investigate the CHANDRA X-ray spectrum of Markarian 279, a broad-line Seyfert 1. I use a new code, PHASE, to self-consistently model the entire absorption spectrum simultaneously. Using solely the X-ray spectrum I am able to determine the physical parameters of this absorber to a degree only

  14. The Swift AGN and Cluster Survey

    NASA Astrophysics Data System (ADS)

    Danae Griffin, Rhiannon; Dai, Xinyu; Kochanek, Christopher S.; Bregman, Joel N.; Nugent, Jenna

    2016-01-01

    The Swift active galactic nucleus (AGN) and Cluster Survey (SACS) uses 125 deg^2 of Swift X-ray Telescope serendipitous fields with variable depths surrounding X-ray bursts to provide a medium depth (4 × 10^-15 erg cm^-2 s^-1) and area survey filling the gap between deep, narrow Chandra/XMM-Newton surveys and wide, shallow ROSAT surveys. Here, we present the first two papers in a series of publications for SACS. In the first paper, we introduce our method and catalog of 22,563 point sources and 442 extended sources. We examine the number counts of the AGN and galaxy cluster populations. SACS provides excellent constraints on the AGN number counts at the bright end with negligible uncertainties due to cosmic variance, and these constraints are consistent with previous measurements. The depth and areal coverage of SACS is well suited for galaxy cluster surveys outside the local universe, reaching z ˜ 1 for massive clusters. In the second paper, we use Sloan Digital Sky Survey (SDSS) DR8 data to study the 203 extended SACS sources that are located within the SDSS footprint. We search for galaxy over-densities in 3-D space using SDSS galaxies and their photometric redshifts near the Swift galaxy cluster candidates. We find 103 Swift clusters with a > 3σ over-density. The remaining targets are potentially located at higher redshifts and require deeper optical follow-up observations for confirmations as galaxy clusters. We present a series of cluster properties including the redshift, BCG magnitude, BCG-to-X-ray center offset, optical richness, X-ray luminosity and red sequences. We compare the observed redshift distribution of the sample with a theoretical model, and find that our sample is complete for z ≤ 0.3 and 80% complete for z ≤ 0.4, consistent with the survey depth of SDSS. We also match our SDSS confirmed Swift clusters to existing cluster catalogs, and find 42, 2 and 1 matches in optical, X-ray and SZ catalogs, respectively, so the majority of these

  15. Supernovae and AGN Driven Galactic Outflows

    NASA Astrophysics Data System (ADS)

    Sharma, Mahavir; Nath, Biman B.

    2013-01-01

    We present analytical solutions for winds from galaxies with a Navarro-Frank-White (NFW) dark matter halo. We consider winds driven by energy and mass injection from multiple supernovae (SNe), as well as momentum injection due to radiation from a central black hole. We find that the wind dynamics depends on three velocity scales: (1) v_\\star ˜ (\\dot{E} / 2 \\dot{M})^{1/2} describes the effect of starburst activity, with \\dot{E} and \\dot{M} as energy and mass injection rate in a central region of radius R; (2) v • ~ (GM •/2R)1/2 for the effect of a central black hole of mass M • on gas at distance R; and (3) v_{s} =(GM_h / 2 {C}r_s)^{1/2}, which is closely related to the circular speed (vc ) for an NFW halo, where rs is the halo scale radius and {C} is a function of the halo concentration parameter. Our generalized formalism, in which we treat both energy and momentum injection from starbursts and radiation from the central active galactic nucleus (AGN), allows us to estimate the wind terminal speed to be (4v 2 sstarf + 6(Γ - 1)v • 2 - 4v 2 s )1/2, where Γ is the ratio of force due to radiation pressure to gravity of the central black hole. Our dynamical model also predicts the following: (1) winds from quiescent star-forming galaxies cannot escape from 1011.5 M ⊙ <= Mh <= 1012.5 M ⊙ galaxies; (2) circumgalactic gas at large distances from galaxies should be present for galaxies in this mass range; (3) for an escaping wind, the wind speed in low- to intermediate-mass galaxies is ~400-1000 km s-1, consistent with observed X-ray temperatures; and (4) winds from massive galaxies with AGNs at Eddington limit have speeds >~ 1000 km s-1. We also find that the ratio [2v 2 sstarf - (1 - Γ)v • 2]/v 2 c dictates the amount of gas lost through winds. Used in conjunction with an appropriate relation between M • and Mh and an appropriate opacity of dust grains in infrared (K band), this ratio has the attractive property of being minimum at a certain halo

  16. Radio AGN in the local universe: unification, triggering and evolution

    NASA Astrophysics Data System (ADS)

    Tadhunter, Clive

    2016-06-01

    Associated with one of the most important forms of active galactic nucleus (AGN) feedback, and showing a strong preference for giant elliptical host galaxies, radio AGN (L_{1.4 GHz} > 10^{24} W Hz^{-1}) are a key sub-class of the overall AGN population. Recently their study has benefitted dramatically from the availability of high-quality data covering the X-ray to far-IR wavelength range obtained with the current generation of ground- and space-based telescope facilities. Reflecting this progress, here I review our current state of understanding of the population of radio AGN at low and intermediate redshifts (z < 0.7), concentrating on their nuclear AGN and host galaxy properties, and covering three interlocking themes: the classification of radio AGN and its interpretation; the triggering and fuelling of the jet and AGN activity; and the evolution of the host galaxies. I show that much of the observed diversity in the AGN properties of radio AGN can be explained in terms of a combination of orientation/anisotropy, mass accretion rate, and variability effects. The detailed morphologies of the host galaxies are consistent with the triggering of strong-line radio galaxies (SLRG) in galaxy mergers. However, the star formation properties and cool ISM contents suggest that the triggering mergers are relatively minor in terms of their gas masses in most cases, and would not lead to major growth of the supermassive black holes and stellar bulges; therefore, apart from a minority (<20 %) that show evidence for higher star formation rates and more massive cool ISM reservoirs, the SLRG represent late-time re-triggering of activity in mature giant elliptical galaxies. In contrast, the host and environmental properties of weak-line radio galaxies (WLRG) with Fanaroff-Riley class I radio morphologies are consistent with more gradual fuelling of the activity via gas accretion at low rates onto the supermassive black holes.

  17. Disentangling AGN and Star Formation in Soft X-Rays

    NASA Technical Reports Server (NTRS)

    LaMassa, Stephanie M.; Heckman, T. M.; Ptak, A.

    2012-01-01

    We have explored the interplay of star formation and active galactic nucleus (AGN) activity in soft X-rays (0.5-2 keV) in two samples of Seyfert 2 galaxies (Sy2s). Using a combination of low-resolution CCD spectra from Chandra and XMM-Newton, we modeled the soft emission of 34 Sy2s using power-law and thermal models. For the 11 sources with high signal-to-noise Chandra imaging of the diffuse host galaxy emission, we estimate the luminosity due to star formation by removing the AGN, fitting the residual emission. The AGN and star formation contributions to the soft X-ray luminosity (i.e., L(sub x,AGN) and L(sub x,SF)) for the remaining 24 Sy2s were estimated from the power-law and thermal luminosities derived from spectral fitting. These luminosities were scaled based on a template derived from XSINGS analysis of normal star-forming galaxies. To account for errors in the luminosities derived from spectral fitting and the spread in the scaling factor, we estimated L(sub x,AGN) and L(sub x,SF))from Monte Carlo simulations. These simulated luminosities agree with L(sub x,AGN) and L(sub x,SF) derived from Chandra imaging analysis within a 3sigma confidence level. Using the infrared [Ne ii]12.8 micron and [O iv]26 micron lines as a proxy of star formation and AGN activity, respectively, we independently disentangle the contributions of these two processes to the total soft X-ray emission. This decomposition generally agrees with L(sub x,SF) and L(sub x,AGN) at the 3 sigma level. In the absence of resolvable nuclear emission, our decomposition method provides a reasonable estimate of emission due to star formation in galaxies hosting type 2 AGNs.

  18. DISENTANGLING AGN AND STAR FORMATION IN SOFT X-RAYS

    SciTech Connect

    LaMassa, Stephanie M.; Heckman, T. M.; Ptak, A.

    2012-10-20

    We have explored the interplay of star formation and active galactic nucleus (AGN) activity in soft X-rays (0.5-2 keV) in two samples of Seyfert 2 galaxies (Sy2s). Using a combination of low-resolution CCD spectra from Chandra and XMM-Newton, we modeled the soft emission of 34 Sy2s using power-law and thermal models. For the 11 sources with high signal-to-noise Chandra imaging of the diffuse host galaxy emission, we estimate the luminosity due to star formation by removing the AGN, fitting the residual emission. The AGN and star formation contributions to the soft X-ray luminosity (i.e., L{sub x,AGN} and L{sub x,SF}) for the remaining 24 Sy2s were estimated from the power-law and thermal luminosities derived from spectral fitting. These luminosities were scaled based on a template derived from XSINGS analysis of normal star-forming galaxies. To account for errors in the luminosities derived from spectral fitting and the spread in the scaling factor, we estimated L{sub x,AGN} and L{sub x,SF} from Monte Carlo simulations. These simulated luminosities agree with L{sub x,AGN} and L{sub x,SF} derived from Chandra imaging analysis within a 3{sigma} confidence level. Using the infrared [Ne II]12.8 {mu}m and [O IV]26 {mu}m lines as a proxy of star formation and AGN activity, respectively, we independently disentangle the contributions of these two processes to the total soft X-ray emission. This decomposition generally agrees with L{sub x,SF} and L{sub x,AGN} at the 3{sigma} level. In the absence of resolvable nuclear emission, our decomposition method provides a reasonable estimate of emission due to star formation in galaxies hosting type 2 AGNs.

  19. Subaru adaptive-optics high-spatial-resolution infrared K- and L'-band imaging search for deeply buried dual AGNs in merging galaxies

    SciTech Connect

    Imanishi, Masatoshi; Saito, Yuriko

    2014-01-01

    We present the results of infrared K- (2.2 μm) and L'-band (3.8 μm) high-spatial-resolution (<0.''2) imaging observations of nearby gas- and dust-rich infrared luminous merging galaxies, assisted by the adaptive optics system on the Subaru 8.2 m telescope. We investigate the presence and frequency of red K – L' compact sources, which are sensitive indicators of active galactic nuclei (AGNs), including AGNs that are deeply buried in gas and dust. We observed 29 merging systems and confirmed at least one AGN in all but one system. However, luminous dual AGNs were detected in only four of the 29 systems (∼14%), despite our method's being sensitive to buried AGNs. For multiple nuclei sources, we compared the estimated AGN luminosities with supermassive black hole (SMBH) masses inferred from large-aperture K-band stellar emission photometry in individual nuclei. We found that mass accretion rates onto SMBHs are significantly different among multiple SMBHs, such that larger-mass SMBHs generally show higher mass accretion rates when normalized to SMBH mass. Our results suggest that non-synchronous mass accretion onto SMBHs in gas- and dust-rich infrared luminous merging galaxies hampers the observational detection of kiloparsec-scale multiple active SMBHs. This could explain the significantly smaller detection fraction of kiloparsec-scale dual AGNs when compared with the number expected from simple theoretical predictions. Our results also indicate that mass accretion onto SMBHs is dominated by local conditions, rather than by global galaxy properties, reinforcing the importance of observations to our understanding of how multiple SMBHs are activated and acquire mass in gas- and dust-rich merging galaxies.

  20. Proteomic analysis of post-nuclear supernatant fraction and percoll-purified membranes prepared from brain cortex of rats exposed to increasing doses of morphine

    PubMed Central

    2014-01-01

    ; Aspartate aminotransferase, ↓2.2×] origin. Surprisingly, the immunoblot analysis of the same PM resolved by 2D-ELFO indicated that the “active”, morphine-induced pool of Gβ subunits represented just a minor fraction of the total signal of Gβ which was decreased 1.2x only. The dominant signal of Gβ was unchanged. Conclusion Brain cortex of rats exposed to increasing doses of morphine is far from being adapted. Significant up-regulation of proteins functionally related to oxidative stress and apoptosis suggests a major change of energy metabolism resulting in the state of severe brain cell “discomfort” or even death. PMID:24528483

  1. X-ray View of Four High-Luminosity Swift-BAT AGN: Unveiling Obscuration and Reflection with Suzaku

    NASA Technical Reports Server (NTRS)

    Fiorettil, V.; Angelini, L.; Mushotzky, R. F.; Koss, M.; Malaguti, G.

    2013-01-01

    Aims. A complete census of obscured Active Galactic Nuclei (AGN) is necessary to reveal the history of the super massive black hole (SMBH) growth and galaxy evolution in the Universe given the complex feedback processes and the fact that much of this growth occurs in an obscured phase. In this context, hard X-ray surveys and dedicated follow-up observations represent a unique tool for selecting highly absorbed AGN and for characterizing the obscuring matter surrounding the SMBH. Here we focus on the absorption and reflection occurring in highly luminous, quasar-like AGN, to study the relation between the geometry of the absorbing matter and the AGN nature (e.g. X-ray, optical, and radio properties), and to help to determine the column density dependency on the AGN luminosity. Methods. The Swift/BAT nine-month survey observed 153 AGN, all with ultra-hard X-ray BAT fluxes in excess of 10(exp -11) erg per square centimeter and an average redshift of 0.03. Among them, four of the most luminous BAT AGN (44.73 less than LogLBAT less than 45.31) were selected as targets of Suzaku follow-up observations: J2246.0+3941 (3C 452), J0407.4+0339 (3C 105), J0318.7+6828, and J0918.5+0425. The column density, scattered/reflected emission, the properties of the Fe K line, and a possible variability are fully analyzed. For the latter, the spectral properties from Chandra, XMM-Newton and Swift/XRT public observations were compared with the present Suzaku analysis, adding an original spectral analysis when non was available from the literature. Results. Of our sample, 3C 452 is the only certain Compton-thick AGN candidate because of i) the high absorption (N(sub H) approximately 4 × 10(exp 23) per square centimeter) and strong Compton reflection; ii) the lack of variability; iii) the "buried" nature, i.e. the low scattering fraction (less than 0.5%) and the extremely low relative [OIII] luminosity. In contrast 3C 105 is not reflection-dominated, despite the comparable column density

  2. Physical properties of simulated galaxy populations at z = 2 - I. Effect of metal-line cooling and feedback from star formation and AGN

    NASA Astrophysics Data System (ADS)

    Haas, Marcel R.; Schaye, Joop; Booth, C. M.; Dalla Vecchia, Claudio; Springel, Volker; Theuns, Tom; Wiersma, Robert P. C.

    2013-11-01

    We use hydrodynamical simulations from the OverWhelmingly Large Simulations (OWLS) project to investigate the dependence of the physical properties of galaxy populations at redshift 2 on metal-line cooling and feedback from star formation and active galactic nuclei (AGN). We find that if the sub-grid feedback from star formation is implemented kinetically, the feedback is only efficient if the initial wind velocity exceeds a critical value. This critical velocity increases with galaxy mass and also if metal-line cooling is included. This suggests that radiative losses quench the winds if their initial velocity is too low. If the feedback is efficient, then the star formation rate is inversely proportional to the amount of energy injected per unit stellar mass formed (which is proportional to the initial mass loading for a fixed wind velocity). This can be understood if the star formation is self-regulating, i.e. if the star formation rate (and thus the gas fraction) increases until the outflow rate balances the inflow rate. Feedback from AGN is efficient at high masses, while increasing the initial wind velocity with gas pressure or halo mass allows one to generate galaxy-wide outflows at all masses. Matching the observed galaxy mass function requires efficient feedback. In particular, the predicted faint-end slope is too steep unless we resort to highly mass loaded winds for low-mass objects. Such efficient feedback from low-mass galaxies (M* ≪ 1010 M⊙) also reduces the discrepancy with the observed specific star formation rates, which are higher than predicted unless the feedback transitions from highly efficient to inefficient just below M* ˜ 5 × 109 M⊙.

  3. Role of reconnection in AGN jets

    NASA Astrophysics Data System (ADS)

    Lyutikov, Maxim

    2003-10-01

    We discuss the possible role of reconnection in electro-magnetically dominated cores of relativistic AGN jets. We suggest that reconnection may proceed in a two-fold fashion: initial explosive collapse on the Alfvén time-scale of a current-carrying jet (which is of the order of the light crossing time) and subsequent slow quasi-steady reconnection. Sites of explosive collapse are associated with bright knots, while steady-state reconnection re-energizes particles in the 'bridges' between the knots. Ohmic dissipation in reconnection layers leads to particle acceleration either by inductive electric fields or by stochastic particle acceleration in the ensuing electro-magnetic turbulence.

  4. K-Ras mutant fraction in A/J mouse lung increases as a function of benzo[a]pyrene dose

    EPA Science Inventory

    K-Ras mutant fraction (MF) was measured to examine the default assumption of low dose linearity in the benzo[a]pyrene (B[a]P) mutational response. Groups of ten male A/J mice (7-9 weeks-old) received a single i.p. injection of 0, 0.05, 0.5, 5, or 50 mg/kg B[a]P, and were sacrifi...

  5. X-ray AGN in the XMM-LSS galaxy clusters: no evidence of AGN suppression

    NASA Astrophysics Data System (ADS)

    Koulouridis, E.; Plionis, M.; Melnyk, O.; Elyiv, A.; Georgantopoulos, I.; Clerc, N.; Surdej, J.; Chiappetti, L.; Pierre, M.

    2014-07-01

    We present a study of the overdensity of X-ray-selected active galactic nuclei (AGN) in 33 galaxy clusters in the XMM-LSS field (The XMM-Newton Large Scale Structure Survey), up to redshift z = 1.05 and further divided into a lower (0.14 ≤ z ≤ 0.35) and a higher redshift (0.43 ≤ z ≤ 1.05) subsample. Previous studies have shown that the presence of X-ray-selected AGN in rich galaxy clusters is suppressed, since their number is significantly lower than what is expected from the high galaxy overdensities in the area. In the current study we have investigated the occurrence of X-ray-selected AGN in low (⟨ Lx,bol ⟩ = 2.7 × 1043 erg/s) and moderate (⟨ Lx,bol ⟩ = 2.4 × 1044 erg/s) X-ray luminosity galaxy clusters in an attempt to trace back the relation between high-density environments and nuclear activity. Owing to the wide contiguous XMM-LSS survey area, we were able to extend the study to the cluster outskirts. We therefore determined the projected overdensity of X-ray point-like sources around each cluster out to 6r500 radius, within δr500 = 1 annulus, with respect to the field expectations based on the X-ray source log N - log S of the XMM-LSS field. To provide robust statistical results we also conducted a consistent stacking analysis separately for the two z ranges. We investigated whether the observed X-ray overdensities are to be expected thanks to the obvious enhancement of galaxy numbers in the cluster environment by also estimating the corresponding optical galaxy overdensities, and we assessed the possible enhancement or suppression of AGN activity in clusters. We find a positive X-ray projected overdensity in both redshift ranges at the first radial bins, which however has the same amplitude as that of optical galaxies. Therefore, no suppression (or enhancement) of X-ray AGN activity with respect to the field is found, in sharp contrast to previous results based on rich galaxy clusters, implying that the mechanisms responsible for the

  6. Assessing AGN feedback models with c iii* measurement and photoionization modeling

    NASA Astrophysics Data System (ADS)

    McGinnis, Daniel J.

    2013-12-01

    Mass outflows in active galactic nuclei (AGN) have been hypothesized to represent a feedback mechanism through which black hole growth and galaxy formation are linked. In order to assess this claim, typical outflow kinetic luminosities must be compared to calculated minimum values that are needed to produce feedback relevance. We have developed a method for placing lower limits on the kinetic luminosity by combining photoionization modeling with column density measurements of a select few ionic species, including C III* 1175 as a measure of gas density. This method is applied to sample AGNs representative of those observed with the Sloan Digital Sky Survey (SDSS) and the Cosmic Origins Spectrograph (HST/COS). We find that although measured kinetic luminosity lower limits for the quasar SDSS J170322.41+23124.3 and Seyfert galaxy Akn 564 are several orders of magnitude less than that required for feedback relevance, our method can be drastically improved with increased signal to noise ratios.

  7. Long Term Profile Variability of Double-Peaked Emission Lines in AGNs

    NASA Astrophysics Data System (ADS)

    Lewis, K.; Eracleous, M.; Halpern, J.; Storchi-Bergmann, T.

    2004-06-01

    An increasing number of AGNs exhibit broad, double-peaked Balmer emission lines, which are thought to arise from the outer regions of the accretion disk which fuels the AGN. The line profiles are observed to vary on a characteristic timescales of 5-10 years. The variability is not a reverberation effect; it is a manifestation of physical changes in the disk. Our group has monitored a set of 20 double-peaked emitters for the past 8 years (longer for some objects). Here, we characterize the variability of the double-peaked Hα line profiles in five objects from our sample. By experimenting with simple models, we find that disks with a single precessing spiral arm are able to reproduce many of the variability trends that are seen in the data.

  8. Herschel Observed Stripe 82 Quasars and Their Host Galaxies: Connections between AGN Activity and host Galaxy Star Formation

    NASA Astrophysics Data System (ADS)

    Dong, X. Y.; Wu, Xue-Bing

    2016-06-01

    In this work, we present a study of 207 quasars selected from the Sloan Digital Sky Survey quasar catalogs and the Herschel Stripe 82 survey. Quasars within this sample are high-luminosity quasars with a mean bolometric luminosity of 1046.4 erg s‑1. The redshift range of this sample is within z < 4, with a mean value of 1.5 ± 0.78. Because we only selected quasars that have been detected in all three Herschel-SPIRE bands, the quasar sample is complete yet highly biased. Based on the multi-wavelength photometric observation data, we conducted a spectral energy distribution (SED) fitting through UV to FIR. Parameters such as active galactic nucleus (AGN) luminosity, far-IR (FIR) luminosity, stellar mass, as well as many other AGN and galaxy properties are deduced from the SED fitting results. The mean star formation rate (SFR) of the sample is 419 M ⊙ yr‑1 and the mean gas mass is ∼1011.3 M ⊙. All of these results point to an IR luminous quasar system. Compared with star formation main sequence (MS) galaxies, at least 80 out of 207 quasars are hosted by starburst galaxies. This supports the statement that luminous AGNs are more likely to be associated with major mergers. The SFR increases with the redshift up to z = 2. It is correlated with the AGN bolometric luminosity, where {L}{{FIR}}\\propto {L}{{Bol}}0.46+/- 0.03. The AGN bolometric luminosity is also correlated with the host galaxy mass and gas mass. Yet the correlation between L FIR and L Bol has higher significant level, implies that the link between AGN accretion and the SFR is more primal. The M BH/M * ratio of our sample is 0.02, higher than the value 0.005 in the local universe. It might indicate an evolutionary trend of the M BH–M * scaling relation.

  9. A bispecific antibody (ScBsAbAgn-2/TSPO) target for Ang-2 and TSPO resulted in therapeutic effects against glioblastomas.

    PubMed

    Li, Jia; Zhang, Zhiming; Lv, Lianjie; Qiao, Haibo; Chen, Xiuju; Zou, Changlin

    2016-04-01

    Antibody-based targeted therapy of cancers requires the antibody targeting of specific molecules inducing tumor cells apoptosis or death. Angiopoietin-2 (Agn-2) and translocator protein (TSPO) are identified as potential target molecules for glioblastoma therapy. The single chain anti-Agn-2 antibody (Anag-2) and anti-TSPO antibody (ATSPO) were obtained by monoclonal antibody screening. In the present study, for specific targeting and killing, we generated a recombinant bispecific antibody comprising a single-chain Fragment variable (ScFv) of anti-human Agn-2 and anti-human TSPO (ScBsAbAgn-2/TSPO), which is the mediator for mitochondrial apoptosis and tumor angiogenesis. In vitro, ScBsAbAgn-2/TSPO simultaneously bounded to both targets with a high antigen-binding affinity to Anag-2 and TSPO compared to the individual antibody. The higher expression of Ang-2 and TSPO was observed in bevacizumab-treated glioblastoma compared to normal rat brain endothelium. We also observed apoptosis-mediated cytotoxicity was improved, which resulted in the elimination of up to 90% of the target cells within 72 h. ScBsAbAgn-2/TSPO inhibited tumor growth, decreased vascular permeability, led to extended survival, improved pericyte coverage, depletion of tumor-associated macrophages, and increased numbers of intratumoral T lymphocytes infiltration in a murine bevacizumab-treated glioblastoma model. These findings were also confirmed ex vivo using glioblastoma cells from bevacizumab-treated rats with glioblastoma. We conclude that ScBsAbAgn-2/TSPO targeting of glioblastoma cell lines can be achieved in vitro and in vivo that the efficient elimination of glioblastoma cells supports the potential of ScBsAbAgn-2/TSPO as a potent, novel immunotherapeutic agent. PMID:26898800

  10. The KMOS AGN Survey at High Redshift (KASHz)

    NASA Astrophysics Data System (ADS)

    Harrison, C.; Alexander, D.; Mullaney, J.; Stott, J.; Swinbank, M.; Arumugam, V.; Bauer, F.; Bower, R.; Bunker, A.; Sharples, R.

    2016-03-01

    The KMOS AGN Survey at High Redshift (KASHz) is an extensive observational programme to obtain spatially resolved spectroscopy of distant galaxies that host rapidly growing supermassive black holes (i.e., active galactic nuclei [AGN]). By exploiting the unique capabilities of KMOS we will spatially resolve the ionised gas kinematics in around 200 such galaxies. A fundamental prediction of galaxy formation models is that AGN inject considerable energy into their host galaxies and ultimately destroy or remove star-forming material via outflows. However, until now, observational constraints of this prediction have been limited to only a small number of distant galaxies. KASHz will provide the strongest constraints to date on the prevalence, properties and impact of ionised outflows in the host galaxies of distant AGN. The survey is described and our first results presented.

  11. Control of gene expression at a bacterial leader RNA, the agn43 gene encoding outer membrane protein Ag43 of Escherichia coli.

    PubMed

    Wallecha, Anu; Oreh, Heather; van der Woude, Marjan W; deHaseth, Pieter L

    2014-08-01

    The family of agn alleles in Escherichia coli pathovars encodes autotransporters that have been implicated in biofilm formation, autoaggregation, and attachment to cells. The alleles all have long leader RNAs preceding the Ag43 translation initiation codon. Here we present an analysis of the agn43 leader RNA from E. coli K-12. We demonstrate the presence of a rho-independent transcription terminator just 28 bp upstream of the main translation start codon and show that it is functional in vitro. Our data indicate that an as-yet-unknown mechanism of antitermination of transcription must be operative in earlier phases of growth. However, as bacterial cell cultures mature, progressively fewer transcripts are able to bypass this terminator. In the K-12 leader sequence, two in-frame translation initiation codons have been identified, one upstream and the other downstream of the transcription terminator. For optimal agn43 expression, both codons need to be present. Translation from the upstream start codon leads to increased downstream agn43 expression. Our findings have revealed two novel modes of regulation of agn43 expression in the leader RNA in addition to the previously well-characterized regulation of phase variation at the agn43 promoter. PMID:24837285

  12. Broad Band Properties of the BAT Selected AGN

    NASA Technical Reports Server (NTRS)

    Mushotzky, Richard; Winter, Lisa; Tueller, jack

    2008-01-01

    We will present the x-ray spectral properties of approximately 150 Burst Alert Telescope (BAT) selected active galactic nuclei (AGN) focusing on the issues of spectral complexity, x-ray absorption and its distribution and that contribution of sources to the x-ray background. If time permits we will also present the nature of the host galaxies of the AGN and their relationship to merger candidates.

  13. A Comprehensive Model for Compton-thick and Compton-thin X-ray Reprocessing in AGN

    NASA Astrophysics Data System (ADS)

    Yaqoob, Tahir

    2009-09-01

    X-ray reprocessing is common in AGN, yet current modeling practices invoke ad hoc components, some of which may be inappropriate in the Compton-thick regime. This results in derived parameters that do not have obvious physical meaning. Our results so far indicate that the universal use of a disk geometry and interpretation of the so-called "reflection fraction" as a solid angle, can be wrong by a factor of ~5 compared to a torus geometry. We propose to compute a comprehensive set of models that improve upon previous work in several critical ways, yielding transmitted, reflected, and fluorescent line spectra that are self-consistent. The models will be suitable for many applications including Chandra grating spectroscopy and studies of AGN populations found in deep surveys, up to z~10.

  14. Young AGN Outburst Running over Older X-Ray Cavities

    NASA Astrophysics Data System (ADS)

    Bogdan, Akos; van Weeren, Reinout Johannes; Kraft, Ralph; Forman, William; Scott, Randall; Giacintucci, Simona; Churazov, Eugene; O'Dea, Christopher; Baum, Stefi; Noell-Storr, Jacob; Jones, Christine

    2015-08-01

    Although the energetic feedback from active galactic nuclei (AGNs) is believed to have a profound effect on the evolution of galaxies and clusters of galaxies, details of AGN heating remain elusive. Here, we study NGC 193 -- a nearby lenticular galaxy in a group -- based on X-ray and radio observations. These data reveal the complex AGN outburst history of the galaxy: we detect a pair of inner X-ray cavities, an outer X-ray cavity, a shock front, and radio lobes extending beyond the inner cavities. We suggest that the inner cavities were produced about 78 Myr ago by a weaker AGN outburst, while the outer cavity, the radio lobes, and the shock front are due to a younger (13-26 Myr) and 4-8 times more powerful outburst. Combining this with the observed morphology of NGC 193, we conclude that NGC 193 likely represents the first example of a second, more powerful, AGN outburst overrunning an older, weaker outburst. These results help us to understand how the outburst energy is dissipated uniformly in the core of galaxies, and therefore may play a crucial role in resolving how AGN outbursts suppress the formation of large cooling flows at cluster centers.

  15. Mini-Survey Of SDSS of [OIII] AGN With Swift

    NASA Technical Reports Server (NTRS)

    Angelini, L.; George, I. M.; Hill, J.; Padgett, C. A.; Mushotzky, R. F.

    2008-01-01

    The number of AGN and their luminosity distribution are crucial parameters for our understanding of the AGN phenomenon. Recent work (e.g. Ferrarese and Merritt 2000) strongly suggests every massive galaxy has a central black hole. However, most of these objects either are not radiating or have been very difficult to detect. We are now in the era of large surveys, and the luminosity function (LF) of AGN has been estimated in various ways. In the X-ray band, Chandra and XMM surveys (e.g., Barger et al. 2005; Hasinger, et al. 2005) have revealed that the LF of Hard X-ray selected AGN shows a strong luminosity-dependent evolution with a dramatic break towards low L(x) (at al z). This is seen for all types of AGN, but is stronger for the broad-line objects (e.g., Steffen et al. 2004). In sharp contrast, the local LF of optically-selected samples shows no such break and no differences between narrow and broad-line objects (Hao et al. 2005). If, as been suggested, hard X-ray and optical emission line can both be fair indicators of AGN activity, it is important to first understand how reliable these characteristics are if we hope to understand the apparent discrepancy in the LFs.

  16. Modeling IR SED of AGN with Spitzer and Herschel data

    NASA Astrophysics Data System (ADS)

    Feltre, A.

    2012-12-01

    One of the remaining open issues in the context of the analysis of Active Galactic Nuclei (AGN) is the evidence that nuclear gravitational accretion is often accompanied by a concurrent starburst (SB) activity. What is, in this picture, the role played by the obscur- ing dust around the nucleus and what do the state of the art AGN torus models have to say? Can the IR data provided by Spitzer and Herschel help us in extensively investigate both phenomena and, if so, how and with what limitations? In this paper we present our contribution to the efforts of answering these questions. We show some of the main results coming from a comparative study of various AGN SED modeling approaches, focusing mostly on the much-debated issue about the morphology of the dust distribution in the toroidal structure surrounding the AGN. We found that the properties of dust in AGN as measured by matching observations (be it broad band IR photometry or IR spectra) with models, strongly depend on the choice of the dust distribution. Then, we present the spec- tral energy distribution (SED) fitting procedure we developed, making make the best use of Spitzer and Herschel SPIRE mid- and far-IR observations, to dig into the role played by the possible presence of an AGN on the host galaxy's properties.

  17. YOUNG AGN OUTBURST RUNNING OVER OLDER X-RAY CAVITIES

    SciTech Connect

    Bogdán, Ákos; Van Weeren, Reinout J.; Kraft, Ralph P.; Forman, William R.; Randall, Scott; Jones, Christine; Giacintucci, Simona; Churazov, Eugene; O'Dea, Christopher P.; Baum, Stefi A.; Noell-Storr, Jacob

    2014-02-20

    Although the energetic feedback from active galactic nuclei (AGNs) is believed to have a profound effect on the evolution of galaxies and clusters of galaxies, details of AGN heating remain elusive. Here, we study NGC 193—a nearby lenticular galaxy—based on X-ray (Chandra) and radio (Very Large Array and Giant Meter-wave Radio Telescope) observations. These data reveal the complex AGN outburst history of the galaxy: we detect a pair of inner X-ray cavities, an outer X-ray cavity, a shock front, and radio lobes extending beyond the inner cavities. We suggest that the inner cavities were produced ∼78 Myr ago by a weaker AGN outburst, while the outer cavity, the radio lobes, and the shock front are due to a younger (13-26 Myr) and 4-8 times more powerful outburst. Combining this with the observed morphology of NGC 193, we conclude that NGC 193 likely represents the first example of a second, more powerful, AGN outburst overrunning an older, weaker outburst. These results help us to understand how the outburst energy is dissipated uniformly in the core of galaxies, and therefore may play a crucial role in resolving how AGN outbursts suppress the formation of large cooling flows at cluster centers.

  18. On the physical origin of AGN outflow driving mechanisms

    NASA Astrophysics Data System (ADS)

    Ishibashi, Wako

    2016-07-01

    Super-massive black holes in active galactic nuclei (AGN) respond to the accretion process by feeding back energy and momentum into the surrounding environment. Galaxy-scale outflows are thought to provide the physical link connecting the small scales of the central black hole to the large scales of the host galaxy. Such powerful outflows are now starting to be commonly observed, and have been considered as a proof of AGN feedback in action. However, the physical origin of the mechanism driving the observed outflows is still unclear, and whether it is due to energy-driving or radiation-driving is a source of much debate in the literature. We consider AGN feedback driven by radiation pressure on dust, and show that AGN radiative feedback is capable of driving powerful outflows on galactic scales. In particular, we can obtain outflowing shells with high velocity and large momentum flux, by properly taking into account the effects of radiation trapping. Alternatively, the observed outflow characteristics may be significantly biased by AGN variability. I will discuss the resulting implications in the global context of black hole accretion-AGN feedback coupling.

  19. SUPERNOVAE AND AGN DRIVEN GALACTIC OUTFLOWS

    SciTech Connect

    Sharma, Mahavir; Nath, Biman B. E-mail: biman@rri.res.in

    2013-01-20

    We present analytical solutions for winds from galaxies with a Navarro-Frank-White (NFW) dark matter halo. We consider winds driven by energy and mass injection from multiple supernovae (SNe), as well as momentum injection due to radiation from a central black hole. We find that the wind dynamics depends on three velocity scales: (1) v{sub *}{approx}( E-dot / 2 M-dot ){sup 1/2} describes the effect of starburst activity, with E-dot and M-dot as energy and mass injection rate in a central region of radius R; (2) v {sub .} {approx} (GM {sub .}/2R){sup 1/2} for the effect of a central black hole of mass M {sub .} on gas at distance R; and (3) v{sub s}=(GM{sub h} / 2Cr{sub s}){sup 1/2}, which is closely related to the circular speed (v{sub c} ) for an NFW halo, where r{sub s} is the halo scale radius and C is a function of the halo concentration parameter. Our generalized formalism, in which we treat both energy and momentum injection from starbursts and radiation from the central active galactic nucleus (AGN), allows us to estimate the wind terminal speed to be (4v {sup 2} {sub *} + 6({Gamma} - 1)v {sub .} {sup 2} - 4v {sup 2} {sub s}){sup 1/2}, where {Gamma} is the ratio of force due to radiation pressure to gravity of the central black hole. Our dynamical model also predicts the following: (1) winds from quiescent star-forming galaxies cannot escape from 10{sup 11.5} M {sub Sun} {<=} M{sub h} {<=} 10{sup 12.5} M {sub Sun} galaxies; (2) circumgalactic gas at large distances from galaxies should be present for galaxies in this mass range; (3) for an escaping wind, the wind speed in low- to intermediate-mass galaxies is {approx}400-1000 km s{sup -1}, consistent with observed X-ray temperatures; and (4) winds from massive galaxies with AGNs at Eddington limit have speeds {approx}> 1000 km s{sup -1}. We also find that the ratio [2v {sup 2} {sub *} - (1 - {Gamma})v {sub .} {sup 2}]/v {sup 2} {sub c} dictates the amount of gas lost through winds. Used in conjunction with

  20. Obscured AGNs in Bulgeless Hosts discovered by WISE: The Case Study of SDSS J1224+5555

    NASA Astrophysics Data System (ADS)

    Satyapal, S.; Secrest, N. J.; Rothberg, B.; O’Connor, J. A.; Ellison, S. L.; Hickox, R. C.; Constantin, A.; Gliozzi, M.; Rosenberg, J. L.

    2016-08-01

    There is mounting evidence that supermassive black holes (SMBHs) form and grow in bulgeless galaxies. However, a robust determination of the fraction of active galactic nuclei (AGNs) in bulgeless galaxies, an important constraint to models of SMBH seed formation and merger-free models of AGN fueling, is unknown, since optical studies have been shown to be incomplete for AGNs in low-mass galaxies. In a recent study using the Wide-field Infrared Survey Explorer, we discovered hundreds of bulgeless galaxies that display mid-infrared signatures of extremely hot dust suggestive of powerful accreting massive black holes, despite having no signatures of black hole activity at optical wavelengths. Here we report X-ray follow-up observations of J122434.66+555522.3, a nearby (z = 0.052) isolated bulgeless galaxy that contains an unresolved X-ray source detected at the 3σ level by XMM-Newton with an observed luminosity uncorrected for intrinsic absorption of {L}2-10{keV}=(1.1+/- 0.4)× {10}40 erg s‑1. Ground-based near-infrared spectroscopy with the Large Binocular Telescope and multiwavelength observations from ultraviolet to millimeter wavelengths together suggest that J1224+5555 harbors a highly absorbed AGN with an intrinsic absorption of {N}{{H}}\\gt {10}24 cm‑2. The hard X-ray luminosity of the putative AGN corrected for absorption is {L}2-10{keV}∼ 3× {10}42 erg s‑1, which, depending on the bolometric correction factor, corresponds to a bolometric luminosity of the AGN of {L}{bol}.∼ 6× {10}43‑3 × 1044 {erg} {{{s}}}-1 and a lower mass limit for the black hole of {M}{BH}≃ 2× {10}6 {M}ȯ , based on the Eddington limit. While enhanced X-ray emission and hot dust can be produced by star formation in extremely low metallicity environments typical in dwarf galaxies, J1224+5555 has a stellar mass of ∼ 2.0× {10}10 {M}ȯ and an above solar metallicity (12 + {logO}/{{H}} = 9.11), typical of our WISE-selected bulgeless galaxy sample. While collectively these

  1. Obscured AGNs in Bulgeless Hosts discovered by WISE: The Case Study of SDSS J1224+5555

    NASA Astrophysics Data System (ADS)

    Satyapal, S.; Secrest, N. J.; Rothberg, B.; O’Connor, J. A.; Ellison, S. L.; Hickox, R. C.; Constantin, A.; Gliozzi, M.; Rosenberg, J. L.

    2016-08-01

    There is mounting evidence that supermassive black holes (SMBHs) form and grow in bulgeless galaxies. However, a robust determination of the fraction of active galactic nuclei (AGNs) in bulgeless galaxies, an important constraint to models of SMBH seed formation and merger-free models of AGN fueling, is unknown, since optical studies have been shown to be incomplete for AGNs in low-mass galaxies. In a recent study using the Wide-field Infrared Survey Explorer, we discovered hundreds of bulgeless galaxies that display mid-infrared signatures of extremely hot dust suggestive of powerful accreting massive black holes, despite having no signatures of black hole activity at optical wavelengths. Here we report X-ray follow-up observations of J122434.66+555522.3, a nearby (z = 0.052) isolated bulgeless galaxy that contains an unresolved X-ray source detected at the 3σ level by XMM-Newton with an observed luminosity uncorrected for intrinsic absorption of {L}2-10{keV}=(1.1+/- 0.4)× {10}40 erg s‑1. Ground-based near-infrared spectroscopy with the Large Binocular Telescope and multiwavelength observations from ultraviolet to millimeter wavelengths together suggest that J1224+5555 harbors a highly absorbed AGN with an intrinsic absorption of {N}{{H}}\\gt {10}24 cm‑2. The hard X-ray luminosity of the putative AGN corrected for absorption is {L}2-10{keV}˜ 3× {10}42 erg s‑1, which, depending on the bolometric correction factor, corresponds to a bolometric luminosity of the AGN of {L}{bol}.˜ 6× {10}43‑3 × 1044 {erg} {{{s}}}-1 and a lower mass limit for the black hole of {M}{BH}≃ 2× {10}6 {M}ȯ , based on the Eddington limit. While enhanced X-ray emission and hot dust can be produced by star formation in extremely low metallicity environments typical in dwarf galaxies, J1224+5555 has a stellar mass of ˜ 2.0× {10}10 {M}ȯ and an above solar metallicity (12 + {logO}/{{H}} = 9.11), typical of our WISE-selected bulgeless galaxy sample. While collectively these

  2. The evolution of and starburst-agn connection in luminous and ultraluminous infrared galaxies and their link to globular cluster formation

    NASA Astrophysics Data System (ADS)

    Fiorenza, Stephanie Lynn

    increased AGN activity if they are older. However, I also find that a young U/LIRG can show a relatively large amount of AGN activity if a very large starburst is present. Then, I quantify the timescales at which the starburst activity in my U/LIRGs evolves with the use of the Tukey-Kramer method of statistical analysis, and fit an exponential curve to the data to describe the expected amount of decrease in SFR seen for a U/LIRG in my sample over a given change in starburst age. Finally, I find evidence that the stellar mass and starburst mass fractions influence whether a U/LIRG in my sample will have a strong AGN and SFR, respectively. I compare the SFR-Mstar relationship seen in my sample with those predicted by models and found from previous observations. I find that the U/LIRGs with older starbursts (>125 Myr) agree with previous results, while those with younger starbursts show a large dispersion in Mstar. I conclude that this is supporting evidence that the star formation histories and timescales at which the IR power sources in U/LIRGs evolve are responsible for the scatter found for the SFR-Mstar relationship. U/LIRGs that form from merging gas-rich disk galaxies could also represent a stage of galaxy evolution involving heavy formation of globular clusters (GCs). It has been suggested that a large number of stellar clusters form during the merging of two gas-rich disk galaxies, leading to open and young massive clusters with the latter likely evolving into GCs. Furthering our understanding of GC formation can uncover the connection between GCs and their host galaxies, which could, at some point during their formation or evolution, be U/LIRGs. To understand GC formation in the context of hierarchical galaxy formation, it is necessary to understand the origin of their abundance patterns. To this effort, I use SDSS spectra from Data Release 8 and 9 to estimate carbon (C) abundances for five GCs by matching synthetic spectra, created with TURBOSPECTRUM using

  3. The space density of Compton-thick AGN at z ≈ 0.8 in the zCOSMOS-Bright Survey

    NASA Astrophysics Data System (ADS)

    Vignali, C.; Mignoli, M.; Gilli, R.; Comastri, A.; Iwasawa, K.; Zamorani, G.; Mainieri, V.; Bongiorno, A.

    2014-11-01

    Context. The obscured accretion phase in black hole growth is a crucial ingredient in many models linking the active galactic nuclei (AGN) activity with the evolution of their host galaxy. At present, a complete census of obscured AGN is still missing, although several attempts in this direction have been carried out recently, mostly in the hard X-rays and at mid-infrared wavelengths. Aims: The purpose of this work is to assess whether the [Ne v] emission line at 3426 Å can reliably pick up obscured AGN up to z ≈ 1 by assuming that it is a reliable proxy of the intrinsic AGN luminosity and using moderately deep X-ray data to characterize the amount of obscuration. Methods: A sample of 69 narrow-line (Type 2) AGN at z ≈ 0.65-1.20 were selected from the 20k-zCOSMOS Bright galaxy sample on the basis of the presence of the [Ne v]3426 Å emission. The X-ray properties of these galaxies were then derived using the Chandra-COSMOS coverage of the field; the X-ray-to-[Ne v] flux ratio, coupled with X-ray spectral and stacking analyses, was then used to infer whether Compton-thin or Compton-thick absorption is present in these sources. Then the [Ne v] luminosity function was computed to estimate the space density of Compton-thick AGN at z ≈ 0.8. Results: Twenty-three sources were detected by Chandra, and their properties are consistent with moderate obscuration (on average, ≈a few × 1022 cm-2). The X-ray properties of the remaining 46 X-ray undetected Type 2 AGN (among which we expect to find the most heavily obscured objects) were derived using X-ray stacking analysis. Current data, supported by Monte Carlo simulations, indicate that a fraction as high as ≈40% of the present sample is likely to be Compton thick. The space density of Compton-thick AGN with logL2-10 keV> 43.5 at z = 0.83 is ΦThick = (9.1 ± 2.1) × 10-6 Mpc-3, in good agreement with both X-ray background model expectations and the previously measured space density for objects in a similar

  4. Investigating AGN Variability Using Combined Multi-Quarter Kepler Data

    NASA Astrophysics Data System (ADS)

    Revalski, Mitchell; Nowak, D.; Wiita, P. J.; Wehrle, A. E.; Unwin, S. C.

    2014-01-01

    The study of long and short term variability in active galactic nuclei (AGN) yields deeper insight into the physical nature of their emissions from the accretion disk around, and relativistic jets powered by, a galaxy’s central super-massive black hole. We have now obtained a total of eleven quarters of Kepler data on four radio-loud AGN. Our prior work involved calculating power spectral densities (PSDs) on these data both with and without corrections for various instrumental artifacts. We now focus on combining these data sets into one continuous set for each object which spans approximately 2.5 years at a 30 minute sampling rate with >98% duty cycle. The process of stringing together these data is complicated by the quarterly rolls the Kepler space satellite telescope conducts, which causes each target to fall on a different CCD four times per year. We attempt to overcome this problem with a scaling procedure that maintains the original percentage of variations and scales all eleven quarters to the overall average. We calculate PSDs on these stitched light curves both with and without various end-matching techniques applied to increase the accuracy of the PSDs. The PSDs computed for the stitched light curves allow us to probe a full decade lower in frequency than our previous work and show comparable slopes to the PSDs calculated for individual quarters, suggesting we are linking the quarters appropriately. Our average PSD slopes are consistent with ground based observations of other quasars, falling approximately between -1.6 and -1.9. In addition, we have used original codes to bin and average individual PSDs to reduce the bias introduced on the slope fitting process induced by the uneven population of points in the PSDs. This allows for a more accurate power law fitting and tends to steepen the overall slope by approximately 0.1 in the majority of cases. We note increased flaring in one of our objects on the order of 15%, with our remaining three objects

  5. Extending ROSAT Light Curves of Ecliptic Pole AGN Formation and Galaxy Evolution

    NASA Technical Reports Server (NTRS)

    Malkan, Matthew A.

    1997-01-01

    In collaboration with UCLA graduate student Fred Baganoff, Professor Malkan has obtained the longest continuous light curves ever available for a large sample (# = 60) of active galactic nuclei. This was accomplished by using the ROSATAII-Sky Survey, which covered the ecliptic pole regions once every 9O-minute orbit. Using this Astrophysics Data Processing grant from NASA, we extended these light curves by combining the RASS data with pointed observations over the next several years of operation of the ROSAT PSPC. This lengthens the baselines of about half of the light curves from a few months up to a few years. The proportion of AGN showing variability increases substantially with this improvement. In fact most AGN in this representative sample are now shown to be significantly variable in the X-rays. We are also able to say something about the amplitudes of variability on timescales from days to years, with more detail than previously has been possible. We have also identified some dependence of the X-ray variability properties on a) the luminosity of the AGN; and b) The presence of a "Blazar" nucleus. By extending the ROSAT light curves, we are also able to learn more about the correlation of X-ray and optical emission on longer time-scales. It appears to be very weak, at best.

  6. Mini Survey of SDSS [OIII] AGN with Swift: Testing the Hypothesis that L(sub [OIII]) Traces AGN Luminosity

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The number of AGN and their luminosity distribution are crucial parameters for our understanding of the AGN phenomenon. Recent work strongly suggests every massive galaxy has a central black hole. However most of these objects either are not radiating or have been very difficult to detect We are now in the era of large surveys, and the luminosity function (LF] of AGN has been estimated in various ways. In the X-ray band. Chandra and XMM surveys have revealed that the LF of hard X-ray selected AGN shows a strong luminosity-dependent evolution with a dramatic break towards low L(sub x) (at all z). This is seen for all types of AGN, but is stronger for the broad-line objects. In sharp contrast, the local LF of optically-selected samples shows no such break and no differences between narrow and broad-line objects. If as been suggested, hard X ray and optical emission line can both can be fair indicators of AGN activity, it is important to first understand how reliable these characteristics are if we hope to understand the apparent discrepancy in the LFs.

  7. Fractional oscillator.

    PubMed

    Stanislavsky, A A

    2004-11-01

    We consider a fractional oscillator which is a generalization of the conventional linear oscillator in the framework of fractional calculus. It is interpreted as an ensemble average of ordinary harmonic oscillators governed by a stochastic time arrow. The intrinsic absorption of the fractional oscillator results from the full contribution of the harmonic oscillator ensemble: these oscillators differ a little from each other in frequency so that each response is compensated by an antiphase response of another harmonic oscillator. This allows one to draw a parallel in the dispersion analysis for media described by a fractional oscillator and an ensemble of ordinary harmonic oscillators with damping. The features of this analysis are discussed. PMID:15600586

  8. The Suzaku View of Highly Ionized Outflows in AGN. 1; Statistical Detection and Global Absorber Properties

    NASA Technical Reports Server (NTRS)

    Gofford, Jason; Reeves, James N.; Tombesi, Francesco; Braito, Valentina; Turner, T. Jane; Miller, Lance; Cappi, Massimo

    2013-01-01

    We present the results of a new spectroscopic study of Fe K-band absorption in active galactic nuclei (AGN). Using data obtained from the Suzaku public archive we have performed a statistically driven blind search for Fe XXV Healpha and/or Fe XXVI Lyalpha absorption lines in a large sample of 51 Type 1.0-1.9 AGN. Through extensive Monte Carlo simulations we find that statistically significant absorption is detected at E greater than or approximately equal to 6.7 keV in 20/51 sources at the P(sub MC) greater than or equal tov 95 per cent level, which corresponds to approximately 40 per cent of the total sample. In all cases, individual absorption lines are detected independently and simultaneously amongst the two (or three) available X-ray imaging spectrometer detectors, which confirms the robustness of the line detections. The most frequently observed outflow phenomenology consists of two discrete absorption troughs corresponding to Fe XXV Healpha and Fe XXVI Lyalpha at a common velocity shift. From xstar fitting the mean column density and ionization parameter for the Fe K absorption components are log (N(sub H) per square centimeter)) is approximately equal to 23 and log (Xi/erg centimeter per second) is approximately equal to 4.5, respectively. Measured outflow velocities span a continuous range from less than1500 kilometers per second up to approximately100 000 kilometers per second, with mean and median values of approximately 0.1 c and approximately 0.056 c, respectively. The results of this work are consistent with those recently obtained using XMM-Newton and independently provides strong evidence for the existence of very highly ionized circumnuclear material in a significant fraction of both radio-quiet and radio-loud AGN in the local universe.

  9. Ionized Outflows in 3-D Insights from Herbig-Haro Objects and Applications to Nearby AGN

    NASA Technical Reports Server (NTRS)

    Cecil, Gerald

    1999-01-01

    HST shows that the gas distributions of these objects are complex and clump at the limit of resolution. HST spectra have lumpy emission-line profiles, indicating unresolved sub-structure. The advantages of 3D over slits on gas so distributed are: robust flux estimates of various dynamical systems projected along lines of sight, sensitivity to fainter spectral lines that are physical diagnostics (reddening-gas density, T, excitation mechanisms, abundances), and improved prospects for recovery of unobserved dimensions of phase-space. These advantages al- low more confident modeling for more profound inquiry into underlying dynamics. The main complication is the effort required to link multi- frequency datasets that optimally track the energy flow through various phases of the ISM. This tedium has limited the number of objects that have been thoroughly analyzed to the a priori most spectacular systems. For HHO'S, proper-motions constrain the ambient B-field, shock velocity, gas abundances, mass-loss rates, source duty-cycle, and tie-ins with molecular flows. If the shock speed, hence ionization fraction, is indeed small then the ionized gas is a significant part of the flow energetics. For AGN'S, nuclear beaming is a source of ionization ambiguity. Establishing the energetics of the outflow is critical to determining how the accretion disk loses its energy. CXO will provide new constraints (especially spectral) on AGN outflows, and STIS UV-spectroscopy is also constraining cloud properties (although limited by extinction). HHO's show some of the things that we will find around AGN'S. I illustrate these points with results from ground-based and HST programs being pursued with collaborators.

  10. Increase in Ultrasonic Intensity of Blood Speckle across Moderate Coronary Artery Stenosis Is an Independent Predictor of Functional Coronary Artery Stenosis Measured by Fractional Flow Reserve: Pilot Study

    PubMed Central

    Tanno, Jun; Nakano, Shintaro; Kasai, Takatoshi; Ako, Junya; Nakamura, Sunao; Senbonmatsu, Takaaki; Nishimura, Shigeyuki

    2015-01-01

    Background and Aims The degree of coronary artery stenosis should be assessed both anatomically and functionally. We observed that the intensity of blood speckle (IBS) on intravascular ultrasound (IVUS) is low proximal to a coronary artery stenosis, and high distal to the stenosis. We defined step-up IBS as the distal minus the proximal IBS, and speculated that this new parameter could be used for the functional evaluation of stenosis on IVUS. The aims of this study were to assess the relationships between step-up IBS and factors that affect coronary blood flow, and between step-up IBS and fractional flow reserve (FFR). Methods and Results This study enrolled 36 consecutive patients with angina who had a single moderate stenosis in the left anterior descending artery. All patients were evaluated by integrated backscatter IVUS and intracoronary pressure measurements. FFR was calculated from measurements using a coronary pressure wire during hyperemia. Conventional gray-scale IVUS images were recorded, and integrated backscatter was measured in three cross-sectional slices proximal and distal to the stenosis. Step-up IBS was calculated as (mean distal integrated backscatter value) − (mean proximal integrated backscatter value). Stepwise multiple linear regression analysis showed that the heart rate (r = 0.45, P = 0.005), ejection fraction (r = −0.39, P = 0.01), and hemoglobin level (r = −0.32, P = 0.04) were independently correlated with step-up IBS, whereas proximal and distal IBS were not associated with these factors. There was a strong inverse correlation between step-up IBS and FFR (r = −0.84, P < 0.001), which remained significant on stepwise multiple linear regression analysis. Conclusions The newly defined parameter of step-up IBS is potentially useful for the functional assessment of coronary artery stenosis. PMID:25607986

  11. Spectropolarimetry of AGN, and `Women &\\ Science'

    NASA Astrophysics Data System (ADS)

    Kay, L.

    1999-12-01

    I have been using optical spectropolarimetry to investigate the nature of AGN. For the CAREER project, I have worked with A. M. Magalhães of the IAG in Brazil to use a visiting polarimetry module with the RC Spectrograph at CTIO, as well as conduct observations at Lick. Projects include observations of broad--line radio galaxies with double--peaked emission line profiles suggestive of accretion disks, and observations of a sample of X-ray selected narrow--line Seyfert 1 galaxies. Another project involves optical and X-ray observations of a complete sample of nearby Seyfert 2 galaxies in order to investigate the frequency of obscured broad--line regions and to determine their contribution to the X-ray background. In addition to involving undergraduate students in research, my educational efforts have focused on getting science into our Women's Studies program. I teach a course on the history and sociology of women in science, co-teach a course on feminist science studies, helped to create a course on women's health, organized a faculty seminar on gender and science issues, and lead a project at Barnard on gender and scientific literacy. I gratefully acknowledge support from NSF CAREER grant AST-9501835, as well as support from NSF International Research Fellowship INT-9423970, and from NSF grant EHR-9555808 to the AAC&U for the Gender and Scientific Literacy project.

  12. Oblique Shocks in AGN Jet Flows

    NASA Astrophysics Data System (ADS)

    Aller, H. D.; Aller, M. F.; Hughes, P. A.; Wardle, J. F. C.; Roberts, D. H.; Homan, D. C.

    2001-12-01

    We present multi-epoch VLBI images and single antenna monitoring results from a study of 10 highly variable AGNs (BL Lacs and QSOs) whose primary goal is to investigate the strengths and orientations of oblique shocks in relativistic flows by comparing observed polarized features found in VLBA total intensity and polarization images and UMRAO monitoring data with the predictions of simple oblique shock models which account for the effects of relativistic aberration. The data consist of weekly observations at 14.5, 8.0 and 4.8 GHz using the UMRAO 26-meter telescope, and seven sets of VLBA total flux and polarization images spaced over the past two years at 15 and 43 GHz supplemented by maps at 8 and 22 GHz for a subset known to exhibit significant opacity. The morphological evolution in both structure and polarization revealed by these data are used to provide an estimation of the projected flow deviation and magnetic field orientation at shocks, and initial results from a comparison of the data with newly developed radiative transfer models allowing for a range of shock orientations are presented. This work was supported in part by NSF grant AST-9900723. The UMRAO is supported by the University of Michigan; The National Radio Astronomy Observatory is operated by Associated Universities, Inc, under cooperative agreement with the National Science Foundation.

  13. Radio-Loud AGN: The Suzaku View

    NASA Technical Reports Server (NTRS)

    Sambruna, Rita

    2009-01-01

    We review our Suzaku observations of Broad-Line Radio Galaxies (BLRGs). The continuum above 2 approx.keV in BLRGs is dominated by emission from an accretion flow, with little or no trace of a jet, which is instead expected to emerge at GeV energies and be detected by Fermi. Concerning the physical conditions of the accretion disk, BLRGs are a mixed bag. In some sources the data suggest relatively high disk ionization, in others obscuration of the innermost regions, perhaps by the jet base. While at hard X-rays the distinction between BLRGs and Seyferts appears blurry, one of the cleanest observational differences between the two classes is at soft X-rays, where Seyferts exhibit warm absorbers related to disk winds while BLRGs do not. We discuss the possibility that jet formation inhibits disk winds, and thus is related to the remarkable dearth of absorption features at soft X-rays in BLRGs and other radio-loud AGN.

  14. Using AGN to Observe the Growth of the Cosmic Web

    NASA Astrophysics Data System (ADS)

    Murray, S.; Jones, C.; Forman, W.; Kenter, A.; Vihklinin, A.; Markevitch, M.; Brand, K.; Jannuzi, B.; Kochanek, C.; Eisenstein, D.

    We present X-ray and optical observations of the contiguous 9 3 sq deg XBootes survey made with the ACIS instrument on Chandra The X-ray survey consists of 126 5ksec pointings that achieve a sensitivity of about 4 times10 -15 erg cm -2 s -1 in the 0 5--7 keV band At this sensitivity limit we detect 4642 X-ray sources As part of the AGES galaxy survey in the Bootes region Kochanek et al 2005 we have obtained 1800 redshifts of the X-ray selected objects most of which are AGN yielding a density of sim150 AGN per square degree The mean AGN redshift is 1 3 with the distribution extending to z 4 We have analyzed the spatial distribution of the X-ray selected AGN and compared this to the distribution of the sim20000 AGES galaxies To z sim0 7 the limit of galaxy sample the galaxies and AGN both trace the same structures and show the same web of voids and filaments At larger redshifts the X-ray AGN continue to show the characteristic structure of voids and filaments Quantitatively we computed the spatial 2-point correlation function for the X-ray selected AGN and find that the correlation length r 0 simeq6 4 h -1 Mpc and the exponent gamma simeq-1 7 of the correlation function are similar to the canonical values derived for galaxies In addition we have compared the correlation function in several redshift intervals and find that the correlation length is approximately constant to z sim1 5

  15. SED and Emission Line Properties of Red 2MASS AGN

    NASA Astrophysics Data System (ADS)

    Kuraszkiewicz, Joanna; Wilkes, Belinda J.; Schmidt, Gary; Ghosh, Himel

    2009-09-01

    Radio and far-IR surveys, and modeling of the cosmic X-ray background suggest that a large population of obscured AGN has been missed by traditional, optical surveys. The Two Micron All-Sky Survey (2MASS) has revealed a large population (surface density comparable to that of optically selected AGN with Ks<14.5mag) of mostly nearby (median z=0.25), red, moderately obscured AGN, among which 75% are previously unidentified emission-line AGN, with 85% showing broad emission lines. We present the SED and emission line properties of 44 such red (J-Ks>2) 2MASS AGN observed with Chandra. They lie at z<0.37, span a full range of spectral types (Type 1, intermediate, Type 2),Ks-to-X-ray slopes, and polarization (<13%). Their IR-to-X-ray spectral energy distributions (SEDs) are red in the near-IR/opt/UV showing little or no blue bump. The optical colors are affected by reddening, host galaxy emission, redshift, and in few, highly polarized objects, also by scattered AGN light. The levels of obscuration obtained from optical, X-rays, and far-IR imply N_H AGN light. PCA analysis of the IR-X-ray SED and emission line properties shows that, while obscuration/inclination is important, the dominant cause of variance in the sample (eigenvector 1) is the L/L_{edd} ratio (perhaps because the red near-IR selection limits the range of inclination/obscuration values in our sample). This analysis also distinguishes two sources of obscuration: the host galaxy and circumnuclear absorption.

  16. AGN coronal emission models - I. The predicted radio emission

    NASA Astrophysics Data System (ADS)

    Raginski, I.; Laor, Ari

    2016-06-01

    Accretion discs in active galactic nucleus (AGN) may be associated with coronal gas, as suggested by their X-ray emission. Stellar coronal emission includes radio emission, and AGN corona may also be a significant source for radio emission in radio quiet (RQ) AGN. We calculate the coronal properties required to produce the observed radio emission in RQ AGN, either from synchrotron emission of power-law (PL) electrons, or from cyclosynchrotron emission of hot mildly relativistic thermal electrons. We find that a flat spectrum, as observed in about half of RQ AGN, can be produced by corona with a disc or a spherical configuration, which extends from the innermost regions out to a pc scale. A spectral break to an optically thin power-law emission is expected around 300-1000 GHz, as the innermost corona becomes optically thin. In the case of thermal electrons, a sharp spectral cut-off is expected above the break. The position of the break can be measured with very long baseline interferometry observations, which exclude the cold dust emission, and it can be used to probe the properties of the innermost corona. Assuming equipartition of the coronal thermal energy density, the PL electrons energy density, and the magnetic field, we find that the energy density in a disc corona should scale as ˜R-1.3, to get a flat spectrum. In the spherical case the energy density scales as ˜R-2, and is ˜4 × 10-4 of the AGN radiation energy density. In Paper II we derive additional constraints on the coronal parameters from the Gudel-Benz relation, Lradio/LX-ray ˜ 10- 5, which RQ AGN follow.

  17. OT2_dbrisbin_1: A z=1-2 oxygen survey. II. PAH-selected star forming and AGN sources

    NASA Astrophysics Data System (ADS)

    Brisbin, D.

    2011-09-01

    We are conducting a survey of the [CII] 158um line from galaxies at redshifts 1-2 using our grating spectrometer, ZEUS on the CSO. Our first 13 galaxy survey showed that luminous star forming galaxies in this epoch have moderate intensity kpc-scale star formation likely an extension of the Schmidt-Kennicutt law to very high gas mass fractions. Our AGN dominated systems have similarly large scale, but significantly more intense star formation suggesting punctuated, collision-induced star formation. We were awarded OT1 PACS spectroscopy and PACS/SPIRE photometry of these sources to observe the oxygen [OI], [OIII], and [OIV] fine-structure lines and far-IR continuum to characterize the star formation and AGN activity in these sources. Only two of our sources have been observed to date, but with good astrophysical success. Since the OT1 submission, we have detected 11 more z ~1-2 sources in [CII] with ZEUS. Here we propose an OT2 oxygen line/far-IR continuum study for 10 of these new sources. The new source list significantly enhances our OT1 survey in that (1) we nearly double our sample greatly increasing statistical significance of the results (2) the new group includes 7 Spitzer/PAH sources. PAH emission arises from PDRs tracing the photo-electric heating, while the [CII] and [OI] lines trace the cooling. PAHS therefore trace star formation and, since the features are extremely bright, are excellent redshift indicators. Future missions (e.g. JWST and SPICA/SAFARI) will rely on PAH spectroscopy at high z. It is therefore vital to study PAH emission and its relationship to star formation. The proposed work explores this connection at redshifts 1-2, near the peak of star formation per unit co-moving volume over cosmic time. In this interval ZEUS and PACs share a great synergy with well-matched sensitivities enabling detections of [CII] and oxygen in a wide variety of systems.

  18. Narrow-line X-Ray-selected Galaxies in the Chandra-COSMOS Field. II. Optically Elusive X-Ray AGNs

    NASA Astrophysics Data System (ADS)

    Pons, E.; Elvis, M.; Civano, F.; Watson, M. G.

    2016-06-01

    In the Chandra-COSMOS (C-COSMOS) survey, we have looked for X-ray-selected active galactic nuclei (AGNs), which are not detected as such in the optical, the so-called elusive AGNs. A previous study based on XMM-Newton and Sloan Digital Sky Survey observations has found a sample of 31 X-ray AGNs optically misclassified as star-forming (SF) galaxies at z\\lt 0.4, including 17 elusive Sy2s. Using Chandra observations provides a sample of fainter X-ray sources and so, for a given X-ray luminosity, extends to higher redshifts. To study the elusive Sy2s in the C-COSMOS field, we have removed the NLS1s that contaminate the narrow-line sample. Surprisingly, the contribution of NLS1s is much lower in the C-COSMOS sample (less than 10% of the optically misclassified X-ray AGNs) than in Pons & Watson. The optical misclassification of the X-ray AGNs ({L}{{X}}\\gt {10}42 {erg} {{{s}}}-1) can be explained by the intrinsic weakness of these AGNs, in addition to, in some cases, optical dilution by the host galaxies. Interestingly, we found the fraction of elusive Sy2s (narrow emission-line objects) optically misclassified as SF galaxies up to z∼ 1.4 to be 10% ± 3% to 17% ± 4%, compared to the 6% ± 1.5% of the Pons & Watson work (up to z∼ 0.4). This result seems to indicate an evolution with redshift of the number of elusive Sy2s.

  19. BLACK HOLE MASS AND EDDINGTON RATIO DISTRIBUTION FUNCTIONS OF X-RAY-SELECTED BROAD-LINE AGNs AT z {approx} 1.4 IN THE SUBARU XMM-NEWTON DEEP FIELD

    SciTech Connect

    Nobuta, K.; Akiyama, M.; Ueda, Y.; Hiroi, K.; Ohta, K.; Iwamuro, F.; Yabe, K.; Moritani, Y.; Sumiyoshi, M.; Maihara, T.; Watson, M. G.; Silverman, J.; Tamura, N.; Kimura, M.; Takato, N.; Dalton, G.; Lewis, I.; Bonfield, D.; Lee, H.; Curtis-Lake, E.; and others

    2012-12-20

    In order to investigate the growth of supermassive black holes (SMBHs), we construct the black hole mass function (BHMF) and Eddington ratio distribution function (ERDF) of X-ray-selected broad-line active galactic nuclei (AGNs) at z {approx} 1.4 in the Subaru XMM-Newton Deep Survey (SXDS) field. A significant part of the accretion growth of SMBHs is thought to take place in this redshift range. Black hole masses of X-ray-selected broad-line AGNs are estimated using the width of the broad Mg II line and 3000 A monochromatic luminosity. We supplement the Mg II FWHM values with the H{alpha} FWHM obtained from our NIR spectroscopic survey. Using the black hole masses of broad-line AGNs at redshifts between 1.18 and 1.68, the binned broad-line AGN BHMFs and ERDFs are calculated using the V{sub max} method. To properly account for selection effects that impact the binned estimates, we derive the corrected broad-line AGN BHMFs and ERDFs by applying the maximum likelihood method, assuming that the ERDF is constant regardless of the black hole mass. We do not correct for the non-negligible uncertainties in virial BH mass estimates. If we compare the corrected broad-line AGN BHMF with that in the local universe, then the corrected BHMF at z = 1.4 has a higher number density above 10{sup 8} M{sub Sun} but a lower number density below that mass range. The evolution may be indicative of a downsizing trend of accretion activity among the SMBH population. The evolution of broad-line AGN ERDFs from z = 1.4 to 0 indicates that the fraction of broad-line AGNs with accretion rates close to the Eddington limit is higher at higher redshifts.

  20. Flux upper limits for 47 AGN observed with H.E.S.S. in 2004-2011

    NASA Astrophysics Data System (ADS)

    H.E.S.S. Collaboration; Abramowski, A.; Aharonian, F.; Ait Benkhali, F.; Akhperjanian, A. G.; Angüner, E.; Anton, G.; Balenderan, S.; Balzer, A.; Barnacka, A.; Becherini, Y.; Becker Tjus, J.; Bernlöhr, K.; Birsin, E.; Bissaldi, E.; Biteau, J.; Böttcher, M.; Boisson, C.; Bolmont, J.; Bordas, P.; Brucker, J.; Brun, F.; Brun, P.; Bulik, T.; Carrigan, S.; Casanova, S.; Cerruti, M.; Chadwick, P. M.; Chalme-Calvet, R.; Chaves, R. C. G.; Cheesebrough, A.; Chrétien, M.; Colafrancesco, S.; Cologna, G.; Conrad, J.; Couturier, C.; Cui, Y.; Dalton, M.; Daniel, M. K.; Davids, I. D.; Degrange, B.; Deil, C.; deWilt, P.; Dickinson, H. J.; Djannati-Ataï, A.; Domainko, W.; Drury, L. O.'C.; Dubus, G.; Dutson, K.; Dyks, J.; Dyrda, M.; Edwards, T.; Egberts, K.; Eger, P.; Espigat, P.; Farnier, C.; Fegan, S.; Feinstein, F.; Fernandes, M. V.; Fernandez, D.; Fiasson, A.; Fontaine, G.; Förster, A.; Füßling, M.; Gajdus, M.; Gallant, Y. A.; Garrigoux, T.; Giavitto, G.; Giebels, B.; Glicenstein, J. F.; Grondin, M.-H.; Grudzińska, M.; Häffner, S.; Hahn, J.; Harris, J.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hervet, O.; Hillert, A.; Hinton, J. A.; Hofmann, W.; Hofverberg, P.; Holler, M.; Horns, D.; Jacholkowska, A.; Jahn, C.; Jamrozy, M.; Janiak, M.; Jankowsky, F.; Jung, I.; Kastendieck, M. A.; Katarzyński, K.; Katz, U.; Kaufmann, S.; Khélifi, B.; Kieffer, M.; Klepser, S.; Klochkov, D.; Kluźniak, W.; Kneiske, T.; Kolitzus, D.; Komin, Nu.; Kosack, K.; Krakau, S.; Krayzel, F.; Krüger, P. P.; Laffon, H.; Lamanna, G.; Lefaucheur, J.; Lemière, A.; Lemoine-Goumard, M.; Lenain, J.-P.; Lennarz, D.; Lohse, T.; Lopatin, A.; Lu, C.-C.; Marandon, V.; Marcowith, A.; Marx, R.; Maurin, G.; Maxted, N.; Mayer, M.; McComb, T. J. L.; Méhault, J.; Meintjes, P. J.; Menzler, U.; Meyer, M.; Moderski, R.; Mohamed, M.; Moulin, E.; Murach, T.; Naumann, C. L.; de Naurois, M.; Niemiec, J.; Nolan, S. J.; Oakes, L.; Ohm, S.; de Oña Wilhelmi, E.; Opitz, B.; Ostrowski, M.; Oya, I.; Panter, M.; Parsons, R. D.; Paz Arribas, M.; Pekeur, N. W.; Pelletier, G.; Perez, J.; Petrucci, P.-O.; Peyaud, B.; Pita, S.; Poon, H.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raab, S.; Raue, M.; Reimer, A.; Reimer, O.; Renaud, M.; de los Reyes, R.; Rieger, F.; Rob, L.; Romoli, C.; Rosier-Lees, S.; Rowell, G.; Rudak, B.; Rulten, C. B.; Sahakian, V.; Sanchez, D. A.; Santangelo, A.; Schlickeiser, R.; Schüssler, F.; Schulz, A.; Schwanke, U.; Schwarzburg, S.; Schwemmer, S.; Sol, H.; Spengler, G.; Spies, F.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Stinzing, F.; Stycz, K.; Sushch, I.; Szostek, A.; Tavernet, J.-P.; Tavernier, T.; Taylor, A. M.; Terrier, R.; Tluczykont, M.; Trichard, C.; Valerius, K.; van Eldik, C.; van Soelen, B.; Vasileiadis, G.; Venter, C.; Viana, A.; Vincent, P.; Völk, H. J.; Volpe, F.; Vorster, M.; Vuillaume, T.; Wagner, S. J.; Wagner, P.; Ward, M.; Weidinger, M.; Weitzel, Q.; White, R.; Wierzcholska, A.; Willmann, P.; Wörnlein, A.; Wouters, D.; Zabalza, V.; Zacharias, M.; Zajczyk, A.; Zdziarski, A. A.; Zech, A.; Zechlin, H.-S.

    2014-04-01

    Context. About 40% of the observation time of the High Energy Stereoscopic System (H.E.S.S.) is dedicated to studying active galactic nuclei (AGN), with the aim of increasing the sample of known extragalactic very-high-energy (VHE, E > 100 GeV) sources and constraining the physical processes at play in potential emitters. Aims: H.E.S.S. observations of AGN, spanning a period from April 2004 to December 2011, are investigated to constrain their γ-ray fluxes. Only the 47 sources without significant excess detected at the position of the targets are presented. Methods: Upper limits on VHE fluxes of the targets were computed and a search for variability was performed on the nightly time scale. Results: For 41 objects, the flux upper limits we derived are the most constraining reported to date. These constraints at VHE are compared with the flux level expected from extrapolations of Fermi-LAT measurements in the two-year catalog of AGN. The H.E.S.S. upper limits are at least a factor of two lower than the extrapolated Fermi-LAT fluxes for 11 objects. Taking into account the attenuation by the extragalactic background light reduces the tension for all but two of them, suggesting intrinsic curvature in the high-energy spectra of these two AGN. Conclusions: Compilation efforts led by current VHE instruments are of critical importance for target-selection strategies before the advent of the Cherenkov Telescope Array (CTA).

  1. CHARACTERIZATION OF A SAMPLE OF INTERMEDIATE-TYPE AGNs. I. SPECTROSCOPIC PROPERTIES AND SERENDIPITOUS DISCOVERY OF NEW DUAL AGNs

    SciTech Connect

    Benitez, Erika; Cruz-Gonzalez, Irene; Martinez, Benoni; Jimenez-Bailon, Elena; Mendez-Abreu, Jairo; Lopez-Martin, Luis; Fuentes-Carrera, Isaura; Leon-Tavares, Jonathan; Chavushyan, Vahram H.

    2013-01-20

    A sample of 10 nearby intermediate-type active galactic nuclei (AGNs) drawn from the Sloan Digital Sky Survey is presented. The aim of this work is to provide estimations of the black hole (BH) mass for the sample galaxies from the dynamics of the broad-line region. For this purpose, a detailed spectroscopic analysis of the objects was done. Using Baldwin-Phillips-Terlevich diagnostic diagrams, we have carefully classified the objects as true intermediate-type AGNs and found that 80%{sup +7.2%} {sub -17.3%} are composite AGNs. The BH mass estimated for the sample is within 6.54 {+-} 0.16 < log M {sub BH} < 7.81 {+-} 0.14. Profile analysis shows that five objects (J120655.63+501737.1, J121607.08+504930.0, J141238.14+391836.5, J143031.18+524225.8, and J162952.88+242638.3) have narrow double-peaked emission lines in both the red (H{alpha}, [N II] {lambda}{lambda}6548,6583 and [S II] {lambda}{lambda}6716, 6731) and the blue (H{beta} and [O III] {lambda}{lambda}4959, 5007) regions of the spectra, with velocity differences ({Delta}V) between the double peaks within 114 km s{sup -1} < {Delta}V < 256 km s{sup -1}. Two of them, J121607.08+504930.0 and J141238.14+391836.5, are candidates for dual AGNs since their double-peaked emission lines are dominated by AGN activity. In searches of dual AGNs, type 1, type II, and intermediate-type AGNs should be carefully separated, due to the high serendipitous number of narrow double-peaked sources (50% {+-} 14.4%) found in our sample.

  2. Kiloparsec-scale outflows are prevalent among luminous AGN: outflows and feedback in the context of the overall AGN population

    NASA Astrophysics Data System (ADS)

    Harrison, C. M.; Alexander, D. M.; Mullaney, J. R.; Swinbank, A. M.

    2014-07-01

    We present integral field unit observations covering the [O III]λλ4959, 5007 and Hβ emission lines of 16 z < 0.2 type 2 active galactic nuclei (AGN). Our targets are selected from a well-constrained parent sample of ≈24 000 AGN so that we can place our observations into the context of the overall AGN population. Our targets are radio quiet with star formation rates (SFRs; ≲[10-100] M⊙ yr-1) that are consistent with normal star-forming galaxies. We decouple the kinematics of galaxy dynamics and mergers from outflows. We find high-velocity ionized gas (velocity widths ≈600-1500 km s-1; maximum velocities ≤1700 km s-1) with observed spatial extents of ≳(6-16) kpc in all targets and observe signatures of spherical outflows and bi-polar superbubbles. We show that our targets are representative of z < 0.2, luminous (i.e. L[O III] > 1041.7 erg s-1) type 2 AGN and that ionized outflows are not only common but also in ≥70 per cent (3σ confidence) of cases, they are extended over kiloparsec scales. Our study demonstrates that galaxy-wide energetic outflows are not confined to the most extreme star-forming galaxies or radio-luminous AGN; however, there may be a higher incidence of the most extreme outflow velocities in quasars hosted in ultraluminous infrared galaxies. Both star formation and AGN activity appear to be energetically viable to drive the outflows and we find no definitive evidence that favours one process over the other. Although highly uncertain, we derive mass outflow rates (typically ≈10 times the SFRs), kinetic energies (≈0.5-10 per cent of LAGN) and momentum rates (typically ≳10-20 × LAGN/c) consistent with theoretical models that predict AGN-driven outflows play a significant role in shaping the evolution of galaxies.

  3. AGN and Star Formation in HerMES-IRS sources

    NASA Astrophysics Data System (ADS)

    Feltre, Anna; Hatziminaoglou, Evanthia; Hernán-Caballero, Antonio; Fritz, Jacopo; Franceschini, Alberto

    2014-07-01

    One of the remaining open issues in the context of the analysis of Active Galactic Nuclei (AGN) is the evidence that nuclear gravitational accretion is often accompanied by a concurrent starburst activity. We developed a spectral energy distribution (SED) fitting technique to derive simultaneously the physical properties of active galaxies and coexisting starbursts making the best use of Spitzer and Herschel IR observations. We apply the SED fitting procedure to a large sample of extragalactic sources representing the HerMES (Herschel/Multi-tiered Extragalactic Survey) population with IRS spectra with a plethora of multi-wavelength data in order to study the impact of a possible presence of an AGN on the host galaxy's properties. We analyze the star formation rate (SFR) in conncetion to the presence of an AGN and compared the properties of the hot (AGN) and cold (starburst) dust component. Our findings are consistent with no evidence for the presence of an AGN affecting the star formation processes of the host galaxies.

  4. The New Spectral Picture of Seyfert 1 AGNs

    NASA Astrophysics Data System (ADS)

    Miyake, K.; Noda, H.; Yamada, S.; Makishima, K.

    2014-07-01

    X-ray spectra of active galactic nuclei (AGNs) were so far considered to consist of a single power-law (PL) like primary component and a reflection component accompanied by an FeKα line. However, the assumption of ``single primary component'' has not been confirmed observationally. To overcome this limitation, we developed a method that can decompose observed AGN spectra model-independently using time-variability (Noda et al. 2011, 2013). We applied it to the bright and variable Seyfert 1 AGN, IC4329A. It was observed by Suzaku 5 times in 2007, and once in 2012. Using our method, the time-averaged spectra have been successfully decomposed into a fast-variable component and a slowly-variable one. While the former can be regarded as a PL with photon index Γ~2.1, the latter is explained as a sum of the distant reflection component and a harder PL with Γ~1.4. This harder PL component, observed in all observations of IC 4329A and in many other AGNs (Noda et al. 2011, 2013), can be interpreted neither as partially-covered Γ~2.1 PL, nor relativistic reflection that varies with the primary. Therefore, the Γ~1.4 PL is considered to be another primary component. Its recognition has a big impact on our understanding of the AGN central engine.

  5. Inverse Compton X-ray signature of AGN feedback

    NASA Astrophysics Data System (ADS)

    Bourne, Martin A.; Nayakshin, Sergei

    2013-12-01

    Bright AGN frequently show ultrafast outflows (UFOs) with outflow velocities vout ˜ 0.1c. These outflows may be the source of AGN feedback on their host galaxies sought by galaxy formation modellers. The exact effect of the outflows on the ambient galaxy gas strongly depends on whether the shocked UFOs cool rapidly or not. This in turn depends on whether the shocked electrons share the same temperature as ions (one-temperature regime, 1T) or decouple (2T), as has been recently suggested. Here we calculate the inverse Compton spectrum emitted by such shocks, finding a broad feature potentially detectable either in mid-to-high energy X-rays (1T case) or only in the soft X-rays (2T). We argue that current observations of AGN do not seem to show evidence for the 1T component. The limits on the 2T emission are far weaker, and in fact it is possible that the observed soft X-ray excess of AGN is partially or fully due to the 2T shock emission. This suggests that UFOs are in the energy-driven regime outside the central few pc, and must pump considerable amounts of not only momentum but also energy into the ambient gas. We encourage X-ray observers to look for the inverse Compton components calculated here in order to constrain AGN feedback models further.

  6. A Meeting on the AGN/Galaxy Connection

    NASA Technical Reports Server (NTRS)

    Kinney, Anne

    1999-01-01

    This grant was used for travel support of several junior astronomers to attend the meeting "The Actice Galactic Nuclei (AGN)/Normal Galaxy Connection", Session El.2 of the 32nd COSPAR Assembly held in Nagoya, Japan, 12-19 July 1998. This meeting included the contributions from both theoretical and observational astronomers to the following fundamental questions: What causes the activity in galaxies? What is the difference between normal and active galaxies? Which processes are responsible for fueling the AGN? Do all galaxies have central Black Holes? What is the difference between low and high luminosity AGN? The observational papers discussed themes like: the detection of the black hole at the nucleus of our Galaxy, as well as in other galaxies; results from surveys of AGN in local galaxies, the source of their activity and their cold gas content; the observations of quasar host galaxies; the properties of Ultraluminous Infrared Galaxies. These papers used data from ground based observatories and several space missions (e.g. ASCA, ROSAT, HST, ISO) in wavebands from radio through gamma-rays. The theoretical papers discussed issues like: mechanisms to fuel the AGN; the physics of the accretion process; the formation of black-holes, quasars and their jets.

  7. The QUEST-La Silla AGN Variability Survey

    NASA Astrophysics Data System (ADS)

    Cartier, R.; Lira, P.; Coppi, P.; Sánchez, P.; Arévalo, P.; Bauer, F. E.; Muñoz, R. R.

    2016-03-01

    It is widely believed that supermassive black holes reside at the centres of every massive galaxy. When actively accreting they are known as Active Galactic Nuclei (AGNs). Most commonly, their presence is exposed by the radiation generated by the accretion of matter toward their centres. This radiation can show dramatic flux variations on timescales from minutes to years that can be observed across the full electromagnetic spectrum from X-ray to radio wavelengths. Although the exact origin of AGN variability remains unclear, such variability can be used as an efficient tool to find them and to understand the origin and demographics of flux variations. To this end, we have undertaken an AGN variability survey using the QUEST camera on the ESO 1.0-metre Schmidt Telescope at La Silla. The QUEST-La Silla AGN Variability Survey aims to discover thousands of new AGNs, and provide highly sampled light curves to study the ultraviolet/optical flux variations to a limiting magnitude of r ~ 21.5 mag.

  8. AGN and Starbursts in Dusty Galaxy Mergers: Insights from the Great Observatories All-sky LIRG Survey

    NASA Astrophysics Data System (ADS)

    Mazzarella, Joseph M.

    2014-07-01

    The Great Observatories All-sky LIRG Survey (GOALS) is combining imaging and spectroscopic data from the Herschel, Spitzer, Hubble, GALEX, Chandra, and XMM-Newton space telescopes augmented with extensive ground-based observations in a multiwavelength study of approximately 180 Luminous Infrared Galaxies (LIRGs) and 20 Ultraluminous Infrared Galaxies (ULIRGs) that comprise a statistically complete subset of the 60μm-selected IRAS Revised Bright Galaxy Sample. The objects span the full range of galaxy environments (giant isolated spirals, wide and close pairs, minor and major mergers, merger remnants) and nuclear activity types (Seyfert 1, Seyfert 2, LINER, starburst/HII), with proportions that depend strongly on the total infrared luminosity. I will review the science motivations and present highlights of recent results selected from over 25 peer-reviewed journal articles published recently by the GOALS Team. Statistical investigations include detection of high-ionization Fe K emission indicative of deeply embedded AGN, comparison of UV and far-IR properties, investigations of the fraction of extended emission as a function of wavelength derived from mid-IR spectroscopy, mid-IR spectral diagnostics and spectral energy distributions revealing the relative contributions of AGN and starbursts to powering the bolometric luminosity, and quantitative structure analyses that delineate the evolution of stellar bars and nuclear stellar cusps during the merger process. Multiwavelength dissections of individual systems have unveiled large populations of young star clusters and heavily obscured AGN in early-stage (II Zw 96), intermediate-stage (Mrk 266, Mrk 273), and late-stage (NGC 2623, IC 883) mergers. A recently published study that matches numerical simulations to the observed morphology and gas kinematics in mergers has placed four systems on a timeline spanning 175-260 million years after their first passages, and modeling of additional (U)LIRGs is underway. A very

  9. Coordinated Multifrequency Observations of Variable Agns

    NASA Astrophysics Data System (ADS)

    Worrall, Diana M.

    1984-07-01

    Our ME measurements of BL Lac objects to date, coordinated with observations in other frequency bands, show positive spectral curvature within the infrared to ultraviolet energy range (Worrall and Bruhweiler 1982). There is evidence that this component is synchrotron radiation. In order to fit the spectral measurements, we find that relativistic beaming is an essential ingredient of simple models not involving electron reacceleration. It is important to discover to what extent this is observationally true of all BL Lac objects, and to then compare with expectations of the distribution in Lorentz factor derived from geometrical arguments. Our sample of BL Lac objects so far numbers 5. There are 17 other BL Lac objects for which IUE observations are listed in the master catalogue. However, many of these objects are so heavily contaminated by a galactic component in the visual and near infrared that the data cannot be usefully employed for our purpose. Also, to our knowledge, the necessary nearly simultaneous coverage in the infrared and visual only exists for 6 of these 17. The near-simultaneity is a vital element, since these active galactic nuclei (AGNs) tend to exhibit different flux variability characteristics in the different available wavebands. We present a target list primarily composed of BL Lac objects, but including 3 QSOs. Conclusions from non-simultaneous multifrequency observations by Malkan and Sargent (1982) suggest that one difference between QSOs and BL Lacs is that the non-thermal infrared to ultraviolet QSO flux does not appear to exhibit curvature. We would like to investigate this more closely, with simultaneous observations. We propose to coordinate all our observations with radio, millimeter, infrared and visual wavelength coverage and have calculated time periods during which this will be possible. Final target selection from our list of visually variable objects will be based on their magnitudes just prior to shift allotment.

  10. Agnes Pockels: Life, Letters and Papers

    NASA Astrophysics Data System (ADS)

    Helm, Christiane A.

    2004-03-01

    Agnes Pockels (1862 - 1935) was a German woman, whose studies pioneered surface science. She was born in malaria infected North Italy while her father served in the Austrian army. Because he suffered adverse health effects, the family moved in1871 to Braunschweig (North Germany). There, Pockels went to high school. She was interested in science, but formal training was not available for girls. She took on the role of household manager and nurse as her parents' health deteriorated further. Her diary illustrates the difficulties she faced in trying to maintain her own health, the health of her parents and her scientific research at the same time. When Pockels was 18 or 19, she designed a ring tensiometer. Additionally, she found a new method to introduce water-insoluble compounds to the water surface by dissolving them in an organic solvent, and applying drops of the solution. Her surface film balance technique from 1882 is the basis for the method later developed by Langmuir. Since her experimental work was highly original and in a new field, she failed to get it recognized in her own country. When she was 28, she wrote to Lord Rayleigh, since she had read about his recent experiments in surface physics. Rayleigh was so impressed with her experimental methods and results that he had her letter translated from German and published it in Nature (1891). She continued her research on surface films, interactions of solutions and contact angles (more papers, 3 in Nature). Still, she did all experiments at home. With the death of her brother in 1913 and the onset of the war, she retired into private life. Thus she was surprised when she was awarded in her late 60ies with a honorary doctorate by the TU Braunschweig (1932) and the annual prize of the German Colloid Society (1931).

  11. Atorvastatin and fenofibrate combination induces the predominance of the large HDL subclasses and increased apo AI fractional catabolic rates in New Zealand white rabbits with exogenous hypercholesterolemia.

    PubMed

    Flores-Castillo, Cristobal; Zamora-Pérez, Juan Á; Carreón-Torres, Elizabeth; Arzola-Paniagua, Angélica; Aguilar-Salinas, Carlos; López-Olmos, Victoria; Fragoso, José M; Luna-Luna, María; Rodríguez-Pérez, José M; Franco, Martha; Vargas-Alarcón, Gilberto; Pérez-Méndez, Óscar

    2015-08-01

    The anti-atherogenic properties of high-density lipoproteins (HDLs) may be related to their structure and metabolism. The HDL physicochemical characteristics that determine their plasma clearance during treatment with statins and fibrates are not well understood. In this study, we analyzed HDL-apo AI fractional catabolic rates (FCRs), size distributions, and the lipid composition of the HDL subclasses in New Zealand white rabbits with exogenous dyslipidemia that received low doses of atorvastatin and fenofibrate. Hypercholesterolemia decreased only partially with the combination of both drugs. HDL size distribution shifted toward larger particles among the groups of rabbits that received atorvastatin, fenofibrate, or their combination, compared with both the control group and the dyslipidemic group. The HDL subclasses were significantly rich in cholesterol in each of the groups compared with controls. The structural changes noted in the HDL subclasses were not associated with impaired plasma paraoxonase-1 (PON1) activity. The groups receiving monotherapy and the drug combination group were all associated with a higher apo AI FCR value compared with both the dyslipidemic rabbits and the control group. In conclusion, the combination of atorvastatin and fenofibrate induced a more favorable HDL subclass profile than did the individual use of these drugs. Similarly, the apo AI FCR values were augmented in every group receiving drug treatment (either monotherapy or combination therapy) in the setting of hypercholesterolemia. The anti-atherogenic properties of HDLs, excluding their capacity to bind PON1, may be enhanced by the structural and metabolic modifications induced by the combination of atorvastatin and fenofibrate. PMID:25982284

  12. Light fractionation increases the efficacy of ALA-PDT but not of MAL-PDT: What is the role of (vascular) endothelial cells?

    NASA Astrophysics Data System (ADS)

    de Bruijn, H. S.; de Vijlder, H. C.; de Haas, E. R. M.; van der Ploeg-van den Heuvel, A.; Kruijt, B.; Poel-Dirks, D.; Sterenborg, H. J. C. M.; ten Hagen, T. L. M.; Robinson, D. J.

    2009-06-01

    Photodynamic therapy (PDT) using protoporpyrin IX (PpIX) precursors like 5-aminolevulinic acid (ALA) or methyl-aminolevulinate (MAL) has shown to be effective in the treatment of various skin diseases. Using ALA we have shown in numerous studies a significantly improved efficacy by applying light fractionation with a long dark interval. In contrast, in the hairless mouse model, the PDT efficacy using MAL is unaffected by adopting this approach. More acute edema is found after ALA-PDT suggesting a difference in response of endothelial cells to PDT. To investigate the role of endothelial cells, cryo-sections of hairless mouse skin after 4 hours of topical MAL or ALA application were stained with a fluorescent endothelial cell marker (CD31). Co-localization of this marker with the PpIX fluorescence was performed using the spectral imaging function of the confocal microscope. We have also used intra-vital confocal microscopy to image the PpIX fluorescence distribution in correlation with the vasculature of live mouse skin. Our results show PpIX fluorescence at depth in cryo-sections of mouse skin after 4 hours of topical application. Co-localization has shown to be difficult due to the changes in tissue organization caused by the staining procedure. As expected we found high PpIX fluorescence levels in the epidermis after both MAL and ALA application using intra-vital microscopy. After ALA application more PpIX fluorescence was found deep in the dermal layer of the skin than after MAL. Furthermore we detected localized fluorescence in unidentified structures that could not be correlated to blood vessels or nerves.

  13. Pan-STARRS1 variability of XMM-COSMOS AGN. I. Impact on photometric redshifts

    NASA Astrophysics Data System (ADS)

    Simm, T.; Saglia, R.; Salvato, M.; Bender, R.; Burgett, W. S.; Chambers, K. C.; Draper, P. W.; Flewelling, H.; Kaiser, N.; Kudritzki, R.-P.; Magnier, E. A.; Metcalfe, N.; Tonry, J. L.; Wainscoat, R. J.; Waters, C.

    2015-12-01

    Aims: Upcoming large area sky surveys like Euclid and eROSITA, which are dedicated to studying the role of dark energy in the expansion history of the Universe and the three-dimensional mass distribution of matter, crucially depend on accurate photometric redshifts. The identification of variable sources, such as active galactic nuclei (AGNs), and the achievable redshift accuracy for varying objects are important in view of the science goals of the Euclid and eROSITA missions. Methods: We probe AGN optical variability for a large sample of X-ray-selected AGNs in the XMM-COSMOS field, using the multi-epoch light curves provided by the Pan-STARRS1 (PS1) 3π and Medium Deep Field surveys. To quantify variability we employed a simple statistic to estimate the probability of variability and the normalized excess variance to measure the variability amplitude. Utilizing these two variability parameters, we defined a sample of varying AGNs for every PS1 band. We investigated the influence of variability on the calculation of photometric redshifts by applying three different input photometry sets for our fitting procedure. For each of the five PS1 bands gP1, rP1, iP1, zP1, and yP1, we chose either the epochs minimizing the interval in observing time, the median magnitude values, or randomly drawn light curve points to compute the redshift. In addition, we derived photometric redshifts using PS1 photometry extended by GALEX/IRAC bands. Results: We find that the photometry produced by the 3π survey is sufficient to reliably detect variable sources provided that the fractional variability amplitude is at least ~3%. Considering the photometric redshifts of variable AGNs, we observe that minimizing the time spacing of the chosen points yields superior photometric redshifts in terms of the percentage of outliers (33%) and accuracy (0.07), outperforming the other two approaches. Drawing random points from the light curve gives rise to typically 57% of outliers and an accuracy of

  14. Outflows in infrared-luminous galaxies: Absorption-line spectroscopy of starbursts and AGN

    NASA Astrophysics Data System (ADS)

    Rupke, David S.

    Large-scale galactic outflows, better known as superwinds, are driven by the powerful energy reservoirs in star forming and active galaxies. They play a significant role in galaxy formation, galaxy evolution, and the evolution of the intergalactic medium. We have performed a survey of over 100 infrared-luminous galaxies in order to address the exact frequency with which they occur in different galaxy types, the dependence of their properties on those of their host galaxies, and their properties in the most luminous starburst and active galaxies. Most of our sample consists of ultraluminous infrared galaxies (ULIRGs), and we use moderate- resolution spectroscopy of the Na I D interstellar absorption feature (which directly probes the neutral gas phase). We find superwinds in the majority of these galaxies at typical maximum, deprojected velocities of 500 700 km s-1. The detection rate increases with star formation rate (SFR) in starbursts, while the mass outflow rate appears constant with SFR, contrary to theoretical expectations. The resulting mass entrainment efficiencies in ULIRGs are quite low, of order a few percent of the star formation rate. There is some dependence of outflow velocity on host galaxy properties; the outflow velocities in LINERs are higher than those in H II galaxies, and the highest column density gas in each galaxy may have an upper envelope in velocity that increases with SFR. Outflows in most galaxies hosting a dominant AGN have very similar properties to those in starbursts, so discerning their power source is difficult. The velocities in Seyfert 2 outflows may be slightly higher than those in starbursts, and the fraction of neutral gas escaping Seyfert 2s is higher than that in starbursts (˜50% vs. ≲ 20%). The outflows in our Seyfert 1 galaxies have extreme velocities of up to ˜104 km s-1, and two of three Seyfert is with outflows possess broad absorption lines. Finally, we find that spectroscopy of a few galaxies at very high

  15. The Most Luminous Heavily Obscured Quasars Have a High Merger Fraction: Morphological Study of WISE-selected Hot Dust-obscured Galaxies

    NASA Astrophysics Data System (ADS)

    Fan, Lulu; Han, Yunkun; Fang, Guanwen; Gao, Ying; Zhang, Dandan; Jiang, Xiaoming; Wu, Qiaoqian; Yang, Jun; Li, Zhao

    2016-05-01

    Previous studies have shown that Wide-field Infrared Survey Explorer-selected hyperluminous, hot dust-obscured galaxies (Hot DOGs) are powered by highly dust-obscured, possibly Compton-thick active galactic nuclei (AGNs). High obscuration provides us a good chance to study the host morphology of the most luminous AGNs directly. We analyze the host morphology of 18 Hot DOGs at z ˜ 3 using Hubble Space Telescope/WFC3 imaging. We find that Hot DOGs have a high merger fraction (62 ± 14%). By fitting the surface brightness profiles, we find that the distribution of Sérsic indices in our Hot DOG sample peaks around 2, which suggests that most Hot DOGs have transforming morphologies. We also derive the AGN bolometric luminosity (˜1014 L ⊙) of our Hot DOG sample by using IR spectral energy distributions decomposition. The derived merger fraction and AGN bolometric luminosity relation is well consistent with the variability-based model prediction. Both the high merger fraction in an IR-luminous AGN sample and relatively low merger fraction in a UV/optical-selected, unobscured AGN sample can be expected in the merger-driven evolutionary model. Finally, we conclude that Hot DOGs are merger-driven and may represent a transit phase during the evolution of massive galaxies, transforming from the dusty starburst-dominated phase to the unobscured QSO phase.

  16. The Most Luminous Heavily Obscured Quasars Have a High Merger Fraction: Morphological Study of WISE-selected Hot Dust-obscured Galaxies

    NASA Astrophysics Data System (ADS)

    Fan, Lulu; Han, Yunkun; Fang, Guanwen; Gao, Ying; Zhang, Dandan; Jiang, Xiaoming; Wu, Qiaoqian; Yang, Jun; Li, Zhao

    2016-05-01

    Previous studies have shown that Wide-field Infrared Survey Explorer-selected hyperluminous, hot dust-obscured galaxies (Hot DOGs) are powered by highly dust-obscured, possibly Compton-thick active galactic nuclei (AGNs). High obscuration provides us a good chance to study the host morphology of the most luminous AGNs directly. We analyze the host morphology of 18 Hot DOGs at z ∼ 3 using Hubble Space Telescope/WFC3 imaging. We find that Hot DOGs have a high merger fraction (62 ± 14%). By fitting the surface brightness profiles, we find that the distribution of Sérsic indices in our Hot DOG sample peaks around 2, which suggests that most Hot DOGs have transforming morphologies. We also derive the AGN bolometric luminosity (∼1014 L ⊙) of our Hot DOG sample by using IR spectral energy distributions decomposition. The derived merger fraction and AGN bolometric luminosity relation is well consistent with the variability-based model prediction. Both the high merger fraction in an IR-luminous AGN sample and relatively low merger fraction in a UV/optical-selected, unobscured AGN sample can be expected in the merger-driven evolutionary model. Finally, we conclude that Hot DOGs are merger-driven and may represent a transit phase during the evolution of massive galaxies, transforming from the dusty starburst-dominated phase to the unobscured QSO phase.

  17. The Suzaku view of highly ionized outflows in AGN - II. Location, energetics and scalings with bolometric luminosity

    NASA Astrophysics Data System (ADS)

    Gofford, J.; Reeves, J. N.; McLaughlin, D. E.; Braito, V.; Turner, T. J.; Tombesi, F.; Cappi, M.

    2015-08-01

    Ongoing studies with XMM-Newton have shown that powerful accretion disc winds, as revealed through highly ionized Fe K-shell absorption at E ≥ 6.7 keV, are present in a significant fraction of active galactic nuclei (AGNs) in the local Universe (Tombesi et al. 2010a). In Gofford et al., we analysed a sample of 51 Suzaku-observed AGNs and independently detected Fe K absorption in ˜40 per cent of the sample, and we measured the properties of the absorbing gas. In this work, we build upon these results to consider the properties of the associated wind. On average, the fast winds (vw > 0.01c) are located ˜ 1015-18 cm (typically ˜102-4 rs) from their black hole, their mass outflow rates are of the order of < dot{M}_w > ˜ 0.01-1 M⊙ yr-1 or {˜ }(0.01-1)dot{M}_Edd and kinetic power is constrained to ˜ 1043-45 erg s-1, equivalent to ˜(0.1-10 per cent)LEdd. We find a fundamental correlation between the source bolometric luminosity and the wind velocity, with v_w ∝ L_bol^{α } and α =0.4^{+0.3}_{-0.2} (90 per cent confidence), which indicates that more luminous AGN tend to harbour faster Fe K winds. The mass outflow rate dot{M}_w, kinetic power Lw and momentum flux dot{p}_w of the winds are also consequently correlated with Lbol, such that more massive and more energetic winds are present in more luminous AGN. We investigate these properties in the framework of a continuum-driven wind, showing that the observed relationships are broadly consistent with a wind being accelerated by continuum-scattering. We find that, globally, a significant fraction (˜85 per cent) of the sample can plausibly exceed the Lw/Lbol ˜ 0.5 per cent threshold thought necessary for feedback, while 45 per cent may also exceed the less conservative ˜5 per cent of Lbol threshold as well. This suggests that the winds may be energetically significant for AGN-host-galaxy feedback processes.

  18. Quenching histories of galaxies and the role of AGN feedback

    NASA Astrophysics Data System (ADS)

    Smethurst, Rebecca Jane; Lintott, Chris; Simmons, Brooke; Galaxy Zoo Team

    2016-01-01

    Two open issues in modern astrophysics are: (i) how do galaxies fully quench their star formation and (ii) how is this affected - or not - by AGN feedback? I present the results of a new Bayesian-MCMC analysis of the star formation histories of over 126,000 galaxies across the colour magnitude diagram showing that diverse quenching mechanisms are instrumental in the formation of the present day red sequence. Using classifications from Galaxy Zoo we show that the rate at which quenching can occur is morphologically dependent in each of the blue cloud, green valley and red sequence. We discuss the nature of these possible quenching mechanisms, considering the influence of secular evolution, galaxy interactions and mergers, both with and without black hole activity. We focus particularly on the relationship between these quenched star formation histories and the presence of an AGN by using this new Bayesian method to show a population of type 2 AGN host galaxies have recently (within 2 Gyr) undergone a rapid (τ < 1 Gyr) drop in their star formation rate. With this result we therefore present the first statistically supported observational evidence that AGN feedback is an important mechanism for the cessation of star formation in this population of galaxies. The diversity of this new method also highlights that such rapid quenching histories cannot account fully for all the quenching across the current AGN host population. We demonstrate that slower (τ > 2 Gyr) quenching rates dominate for high stellar mass (log10[M*/M⊙] > 10.75) hosts of AGN with both early- and late-type morphology. We discuss how these results show that both merger-driven and non-merger processes are contributing to the co-evolution of galaxies and supermassive black holes across the entirety of the colour magnitude diagram.

  19. Tracing outflows in the AGN forbidden region with SINFONI

    NASA Astrophysics Data System (ADS)

    Kakkad, D.; Mainieri, V.; Padovani, P.; Cresci, G.; Husemann, B.; Carniani, S.; Brusa, M.; Lamastra, A.; Lanzuisi, G.; Piconcelli, E.; Schramm, M.

    2016-08-01

    Context. Active galactic nucleus (AGN) driven outflows are invoked in numerical simulations to reproduce several observed properties of local galaxies. The z > 1 epoch is of particular interest as it was during this time that the volume averaged star formation and the accretion rate of black holes were at their maximum. Radiatively driven outflows are therefore believed to be common during this epoch. Aims: We aim to trace and characterize outflows in AGN hosts with high mass accretion rates at z > 1 using integral field spectroscopy. We obtain spatially resolved kinematics of the [O iii] λ5007 line in two targets which reveal the morphology and spatial extension of the outflows. Methods: We present SINFONI observations in the J band and the H + K band of five AGNs at 1.2 < z < 2.2. To maximize the chance of observing radiatively driven outflows, our sample was pre-selected based on peculiar values of the Eddington ratio and the hydrogen column density of the surrounding interstellar medium. We observe high velocity (~600-1900 km s-1) and kiloparsec scale extended ionized outflows in at least three of our targets, using [O iii] λ5007 line kinematics tracing the AGN narrow line region. We estimate the total mass of the outflow, the mass outflow rate, and the kinetic power of the outflows based on theoretical models and report on the uncertainties associated with them. Results: We find mass outflow rates of ~1-10 M⊙/yr for the sample presented in this paper. Based on the high star formation rates of the host galaxies, the observed outflow kinetic power, and the expected power due to the AGN, we infer that both star formation and AGN radiation could be the dominant source for the outflows. The outflow models suffer from large uncertainties, hence we call for further detailed observations for an accurate determination of the outflow properties to confirm the exact source of these outflows.

  20. The INTEGRAL/IBIS AGN catalogue: an update

    NASA Astrophysics Data System (ADS)

    Malizia, A.; Landi, R.; Molina, M.; Bassani, L.; Bazzano, A.; Bird, A. J.; Ubertini, P.

    2016-04-01

    In the most recent IBIS survey based on observations performed during the first 1000 orbits of INTEGRAL, are listed 363 high energy emitters firmly associated with AGN, 107 of which are reported here for the first time. We have used X-ray data to image the IBIS 90% error circle of all the AGN in the sample of 107, in order to obtain the correct X-ray counterparts, locate them with arcsec accuracy and therefore pinpoint the correct optical counterparts. This procedure has led to the optical and spectral characterization of the entire sample. This new set consists of 34 broad line or type 1 AGN, 47 narrow line or type 2 AGN, 18 Blazars and 8 sources of unknown class. These 8 sources have been associated with AGN from their positional coincidence with 2MASX/Radio/X-ray sources. Seven high energy emitters have been included since they are considered to be good AGN candidates. Spectral analysis has been already performed on 55 objects and the results from the most recent and/or best statistical measurements have been collected. For the remaining 52 sources, we report the spectral analysis for the first time in this work. We have been able to obtain the full X-ray coverage of the sample making use of data from Swift/XRT, XMM-Newton and NuSTAR. In addition to the spectral characterization of the entire sample, this analysis has enabled us to identify peculiar sources and by comparing different datasets, highlight flux variability in the 2-10 keV and 20-40 keV bands.

  1. The most obscured AGN in the COSMOS field

    NASA Astrophysics Data System (ADS)

    Lanzuisi, G.; Perna, M.; Delvecchio, I.; Berta, S.; Brusa, M.; Cappelluti, N.; Comastri, A.; Gilli, R.; Gruppioni, C.; Mignoli, M.; Pozzi, F.; Vietri, G.; Vignali, C.; Zamorani, G.

    2015-06-01

    Highly obscured active galactic nuclei (AGN) are common in nearby galaxies, but are difficult to observe beyond the local Universe, where they are expected to significantly contribute to the black hole accretion rate density. Furthermore, Compton-thick (CT) absorbers (NH ≳ 1024 cm-2) suppress even the hard X-ray (2-10 keV) AGN nuclear emission, and therefore the column density distribution above 1024 cm-2 is largely unknown. We present the identification and multi-wavelength properties of a heavily obscured (NH ≳ 1025 cm-2), intrinsically luminous (L2-10 > 1044 erg s-1) AGN at z = 0.353 in the COSMOS field. Several independent indicators, such as the shape of the X-ray spectrum, the decomposition of the spectral energy distribution and X-ray/[NeV] and X-ray/6 μm luminosity ratios, agree on the fact that the nuclear emission must be suppressed by a ≳1025 cm-2 column density. The host galaxy properties show that this highly obscured AGN is hosted in a massive star-forming galaxy, showing a barred morphology, which is known to correlate with the presence of CT absorbers. Finally, asymmetric and blueshifted components in several optical high-ionization emission lines indicate the presence of a galactic outflow, possibly driven by the intense AGN activity (LBol/LEdd = 0.3-0.5). Such highly obscured, highly accreting AGN are intrinsically very rare at low redshift, whereas they are expected to be much more common at the peak of the star formation and BH accretion history, at z ~ 2-3. We demonstrate that a fully multi-wavelength approach can recover a sizable sample of such peculiar sources in large and deep surveys such as COSMOS.

  2. The INTEGRAL/IBIS AGN catalogue: an update

    NASA Astrophysics Data System (ADS)

    Malizia, A.; Landi, R.; Molina, M.; Bassani, L.; Bazzano, A.; Bird, A. J.; Ubertini, P.

    2016-07-01

    In the most recent IBIS survey based on observations performed during the first 1000 orbits of INTEGRAL, are listed 363 high-energy emitters firmly associated with AGN, 107 of which are reported here for the first time. We have used X-ray data to image the IBIS 90 per cent error circle of all the AGN in the sample of 107, in order to obtain the correct X-ray counterparts, locate them with arcsec accuracy and therefore pinpoint the correct optical counterparts. This procedure has led to the optical and spectral characterization of the entire sample. This new set consists of 34 broad line or type 1 AGN, 47 narrow line or type 2 AGN, 18 blazars and 8 sources of unknown class. These eight sources have been associated with AGN from their positional coincidence with 2MASX/Radio/X-ray sources. Seven high-energy emitters have been included since they are considered to be good AGN candidates. Spectral analysis has been already performed on 55 objects and the results from the most recent and/or best statistical measurements have been collected. For the remaining 52 sources, we report the spectral analysis for the first time in this work. We have been able to obtain the full X-ray coverage of the sample making use of data from Swift/XRT, XMM-Newton and NuSTAR. In addition to the spectral characterization of the entire sample, this analysis has enabled us to identify peculiar sources and by comparing different data sets, highlight flux variability in the 2-10 keV and 20-40 keV bands.

  3. What Fraction of Active Galaxies Actually Show Outflows?

    NASA Astrophysics Data System (ADS)

    Ganguly, Rajib; Brotherton, M. S.

    2007-12-01

    Outflows from active galactic nuclei (AGNs) seem to be common and are thought to be important from a variety of perspectives: as an agent of chemical enhancement of the interstellar and intergalactic media, as an agent of angular momentum removal from the accreting central engine, and as an agent limiting star formation in starbursting systems by blowing out gas and dust from the host galaxy. To understand these processes, we must determine what fraction of AGNs feature outflows and understand what forms they take. We examine recent surveys of outflows detected in ultraviolet absorption over the entire range of velocities and velocity widths (i.e., broad absorption lines, associated absorption lines, and high-velocity narrow absorption lines). While the fraction of specific forms of outflows depends on AGN properties, the overall fraction displaying outflows is fairly constant, approximately 60%, over many orders of magnitude in luminosity. We discuss implications of this result and ways to refine our understanding of outflows. We acknowledge support from the US National Science Foundation through grant AST 05-07781.

  4. The merging/AGN connection: a case for 3D spectroscopy

    NASA Astrophysics Data System (ADS)

    Sánchez, S. F.; Christensen, L.; Becker, T.; Kelz, A.; Jahnke, K.; Benn, C. R.; García-Lorenzo, B.; Roth, M. M.

    2004-02-01

    We discuss an ongoing study of the connection between galaxy merging/interaction and AGN activity, based on integral field spectroscopy. We focus on the search for AGN ionization in the central regions of mergers, previously not classified as AGNs. We present here the science case, the current status of the project, and plans for future observations.

  5. Soft X-Ray Spectra of AGN Discovered Via Their Hard X-Ray

    NASA Technical Reports Server (NTRS)

    Schwartz, Daniel

    1998-01-01

    This final report is a study of the Active Galactic Nuclei (AGN). Investigation of the soft x-ray spectra of AGN were performed by using their hard x-ray emission. ROSAT observations of AGN was also performed, which allowed for the study of these x-ray spectra and the structures of 7 clusters of galaxies.

  6. On the electron-positron cascade in AGN central engines

    NASA Astrophysics Data System (ADS)

    Ford, Alex; Keenan, Brett; Medvedev, Mikhail

    2016-03-01

    Processes around spinning supermassive black holes (BH) in active galactic nuclei (AGN) are believed to determine how relativistic jets are launched and how the BH energy is extracted. The key ``ingredient'' is the origin of plasma in BH magnetospheres. In order to explore the process of the electron-positron plasma production, we developed a numerical code which models a one-dimensional (along a magnetic field line) dynamics of the cascade. Our simulations show that plasma production is controlled by the spectrum of the ambient photon field, the B-field strength, the BH spin and mass. Implications of our results to the Galactic Center and AGNs are discussed.

  7. The QUEST-La Silla AGN Variability Survey

    NASA Astrophysics Data System (ADS)

    Cartier, Régis; Lira, Paulina; Coppi, Paolo; Sánchez, Paula; Arévalo, Patricia; Bauer, Franz E.; Rabinowitz, David; Zinn, Robert; Muñoz, Ricardo R.; Meza, Nicolás

    2015-09-01

    We present the characterization and initial results from the QUEST-La Silla active galactic nucleus (AGN) variability survey. This is an effort to obtain well-sampled optical light curves in extragalactic fields with unique multiwavelength observations. We present photometry obtained from 2010 to 2012 in the XMM-COSMOS field, which was observed over 150 nights using the QUEST camera on the European Southern Observatory (ESO) Schmidt telescope. The survey uses a broadband filter, the Q band, similar to the union of the g and the r filters, achieving an intrinsic photometric dispersion of 0.05 mag and a systematic error of 0.05 mag in the zero point. Since some detectors of the camera show significant nonlinearity, we use a linear correlation to fit the zero points as a function of the instrumental magnitudes, thus obtaining a good correction to the nonlinear behavior of these detectors. We obtain good photometry to an equivalent limiting magnitude of r˜ 20.5. The astrometry has an internal precision of ˜ 0\\buildrel{\\prime\\prime}\\over{.} 1 and an overall accuracy of 0\\buildrel{\\prime\\prime}\\over{.} 2 when compared to the Sloan Digital Sky Survey. Studying the optical variability of X-ray-detected sources in the XMM-COSMOS field, we find that the survey is ˜75%-80% complete to magnitudes r˜ 20, and ˜67% complete to a magnitude r˜ 21. Additionally, broad-line (BL) AGNs have larger variation amplitude than non-broad-line (NL) AGNs, with ˜80% of the BL AGNs classified as variable, while only ˜21% of the NL AGNs are classified as variable. We also find that ˜22% of objects classified as galaxies (GALs) are also variable. The determination and parameterization of the structure function ({{SF}}{norm}(τ )=A{τ }γ ) of the variable sources show that most BL AGNs are characterized by A\\gt 0.1 and γ \\gt 0.025. It is further shown that NL AGNs and GAL sources occupying the same parameter space in A and γ are very likely to correspond to obscured or low

  8. SPITZER MID-IR SPECTROSCOPY OF POWERFUL 2 JY AND 3CRR RADIO GALAXIES. I. EVIDENCE AGAINST A STRONG STARBURST-AGN CONNECTION IN RADIO-LOUD AGN

    SciTech Connect

    Dicken, D.; Axon, D.; Robinson, A.; Kharb, P.; Tadhunter, C.; Ramos Almeida, C.; Morganti, R.; Kouwenhoven, M. B. N.; Spoon, H.; Inskip, K. J.; Holt, J.; Nesvadba, N. P. H.

    2012-02-01

    We present deep Spitzer/Infrared Spectrograph (IRS) spectra for complete samples of 46 2 Jy radio galaxies (0.05 < z < 0.7) and 19 3CRR FRII radio galaxies (z < 0.1), and use the detection of polycyclic aromatic hydrocarbon (PAH) features to examine the incidence of contemporaneous star formation and radio-loud active galactic nucleus (AGN) activity. Our analysis reveals PAH features in only a minority (30%) of the objects with good IRS spectra. Using the wealth of complementary data available for the 2 Jy and 3CRR samples we make detailed comparisons between a range of star formation diagnostics: optical continuum spectroscopy, mid- to far-IR (MFIR) color, far-IR excess and PAH detection. There is good agreement between the various diagnostic techniques: most candidates identified to have star formation activity on the basis of PAH detection are also identified using at least two of the other techniques. We find that only 35% of the combined 2 Jy and 3CRR sample show evidence for recent star formation activity (RSFA) at optical and/or MFIR wavelengths. This result argues strongly against the idea of a close link between starburst and powerful radio-loud AGN activity, reinforcing the view that, although a large fraction of powerful radio galaxies may be triggered in galaxy interactions, only a minority are triggered at the peaks of star formation activity in major, gas-rich mergers. However, we find that compact radio sources (D < 15 kpc) show a significantly higher incidence of RSFA (>75%) than their more extended counterparts ( Almost-Equal-To 15%-25%). We discuss this result in the context of a possible bias toward the selection of compact radio sources triggered in gas-rich environments.

  9. Fraction Reduction through Continued Fractions

    ERIC Educational Resources Information Center

    Carley, Holly

    2011-01-01

    This article presents a method of reducing fractions without factoring. The ideas presented may be useful as a project for motivated students in an undergraduate number theory course. The discussion is related to the Euclidean Algorithm and its variations may lead to projects or early examples involving efficiency of an algorithm.

  10. High resolution VLBI polarisation imaging of AGN with the Maximum Entropy Method

    NASA Astrophysics Data System (ADS)

    Coughlan, Colm P.; Gabuzda, Denise C.

    2016-08-01

    Radio polarisation images of the jets of Active Galactic Nuclei (AGN) can provide a deep insight into the launching and collimation mechanisms of relativistic jets. However, even at VLBI scales, resolution is often a limiting factor in the conclusions that can be drawn from observations. The Maximum Entropy Method (MEM) is a deconvolution algorithm that can outperform the more common CLEAN algorithm in many cases, particularly when investigating structures present on scales comparable to or smaller than the nominal beam size with "super-resolution". A new implementation of the MEM suitable for single- or multiple-wavelength VLBI polarisation observations has been developed and is described here. Monte Carlo simulations comparing the performances of CLEAN and MEM at reconstructing the properties of model images are presented; these demonstrate the enhanced reliability of MEM over CLEAN when images of the fractional polarisation and polarisation angle are constructed using convolving beams that are appreciably smaller than the full CLEAN beam. The results of using this new MEM software to image VLBA observations of the AGN 0716+714 at six different wavelengths are presented, and compared to corresponding maps obtained with CLEAN. MEM and CLEAN maps of Stokes I, the polarised flux, the fractional polarisation and the polarisation angle are compared for convolving beams ranging from the full CLEAN beam down to a beam one-third of this size. MEM's ability to provide more trustworthy polarisation imaging than a standard CLEAN-based deconvolution when convolving beams appreciably smaller than the full CLEAN beam are used is discussed.

  11. A Method of Identifying AGNs Based on Emission-Line Excess and the Nature of Low-Luminosity AGNs in the Sloan Digital Sky Survey. II. The Nature of Low-Luminosity AGNs

    NASA Astrophysics Data System (ADS)

    Tanaka, Masayuki

    2012-04-01

    We have developed a new method of identifying active galactic nuclei (AGNs) and studied the nature of low-luminosity AGNs in the Sloan Digital Sky Survey. This is the latter part of a series of papers in which we consider correlations between the AGN activities and the host-galaxy properties. Based on a sample of AGNs identified by a new method developed in the former part (2012, PASJ, 64, 36), we found that AGNs typically show extinction of τV = 1.2, and exhibit a wide range of ionization levels. The finding of ionization levels motivated us to use [O II] + [O III] as an indicator of AGN power. We found that AGNs are preferentially located in massive, red, early-type galaxies. Taking into account a selection bias of the Oxygen-excess method, we showed that strong AGNs are located in active star-forming galaxies, and that rapidly growing super-massive black holes are located in rapidly growing galaxies, which clearly shows the coevolution of super-massive black holes and their host galaxies. This is a surprising phenomenon, given that the growths of black holes and host galaxies occur on their respective physical scales which are very different. Interestingly, the AGN power does not strongly correlate with the host-galaxy mass. It seems that the mass works as a ``switch'' for activating AGNs. The absence of AGNs in low-mass galaxies might be due to the absence of super-massive black holes there, but a dedicated observation of the nuclear region of nearby low-mass galaxies would be necessary to obtain a deeper insight into it.

  12. Converting the Audience: A Conversation with Agnes Wilcox

    ERIC Educational Resources Information Center

    Becker, Becky

    2006-01-01

    This article presents a conversation with Agnes Wilcox, Executive Director of Prison Performing Arts in St. Louis, Missouri, about Prison Performing Arts. Although the average person might balk at the notion of interacting with prison inmates, finding it intimidating, worrisome, or self-sacrificial, for Wilcox, Prison Performing Arts is a…

  13. Disc outflows and high-luminosity true type 2 AGN

    NASA Astrophysics Data System (ADS)

    Elitzur, Moshe; Netzer, Hagai

    2016-06-01

    The absence of intrinsic broad-line emission has been reported in a number of active galactic nuclei (AGN), including some with high Eddington ratios. Such `true type 2 AGN' are inherent to the disc-wind scenario for the broad-line region: broad-line emission requires a minimal column density, implying a minimal outflow rate and thus a minimal accretion rate. Here we perform a detailed analysis of the consequences of mass conservation in the process of accretion through a central disc. The resulting constraints on luminosity are consistent with all the cases where claimed detections of true type 2 AGN pass stringent criteria, and predict that intrinsic broad-line emission can disappear at luminosities as high as ˜4 × 1046 erg s-1 and any Eddington ratio, though more detections can be expected at Eddington ratios below ˜1 per cent. Our results are applicable to every disc outflow model, whatever its details and whether clumpy or smooth, irrespective of the wind structure and its underlying dynamics. While other factors, such as changes in spectral energy distribution or covering factor, can affect the intensities of broad emission lines, within this scenario they can only produce true type 2 AGN of higher luminosity then those prescribed by mass conservation.

  14. The search for red AGN with 2MASS

    NASA Technical Reports Server (NTRS)

    Cutri, R. M.; Nelson, B. O.; Kirkpatrick, J. D.; Huchra, J. P.; Smith, P. S.

    2001-01-01

    We present the results of a simple, highly efficient 2MASS color-based survey that has already discovered 140 previously unknown red AGN and QSOs. These objects are near-infrared-bright and relatively nearby; the media redshift of the sample is z=0.25, and all but two have z<0.7.

  15. FLOYDS Classification of Gaia16ann as an AGN

    NASA Astrophysics Data System (ADS)

    Hosseinzadeh, G.; Arcavi, I.; Howell, D. A.; McCully, C.; Valenti, S.

    2016-07-01

    We obtained a spectrum of Gaia16ann on 2016 July 7.5 UT with the robotic FLOYDS instrument mounted on the LCOGT 2-meter telescope on Haleakala, Hawai'i. Using SNID (Blondin & Tonry 2007, ApJ, 666, 1024), we find a good fit to an AGN at redshift z=0.196.

  16. Time Series Analysis of the UV Flickering in AGN

    NASA Technical Reports Server (NTRS)

    Robinson, Edward L.; Welsh, William F.

    2001-01-01

    Many active galactic nuclei (AGN) exhibit large-amplitude luminosity fluctuations on short timescales. The fluctuations lead to a profound conclusion: The size of the emitting region is remarkably small. This observational fact is one of the pillars supporting the AGN paradigm: Prodigious amounts of gravitational potential energy are liberated in an accretion disk around a supermassive black hole. The goals of the research were to extract from the IUE Archive the very best observational characterizations of AGN flickering, and to use these to test and develop models for AGN variability. We hoped to answer these specific questions: 1) What does the intrinsic flickering continuum spectrum look like? 2) What do the intrinsic flickering emission-line profiles look like? 3) What is the power spectrum of the flickering? 4) What is the wavelength dependence of the power spectrum? 5) Is the flickering spectrum timescale dependent? and 6) What do the high-order cross correlation functions look like? A short summary of the papers produced by this research is presented.

  17. The Role of Environment in Fueling Seyfert AGN

    NASA Astrophysics Data System (ADS)

    Hicks, Erin Kathleen Strobel

    2015-08-01

    We consider the role of environment in fueling of Seyfert AGN through a combined analysis of Hubble Space Telescope images and integral field spectroscopy of the ISM in a sample of local AGN. Using visible and near-infrared Hubble Space Telescope images and color maps of over a 100 galaxies we determine the distribution of the cold ISM, as traced by dust. We also measure the two-dimensional distribution and kinematics of the molecular gas, traced by H2 1-0 S(1) emission at 2.12 μm, down to scales of tens of parsecs using OSIRIS at Keck and SINFONI on VLT for a subset of approximately 20 of these galaxies. Informed by these kinematic measurements of the ISM we classify the nuclear dust morphologies of the full sample of galaxies and interpret the significance of these morphologies in terms of inflow. Our relatively small precursor sample (Hicks et al. 2009, Davies et al. 2014) hinted at a connection between the host galaxy environment and the primary mechanism driving gas inward such that fueling of AGN in isolated galaxies occurs primarily via secular processes (e.g. nuclear spirals) and galaxies in groups of 10-15 members via accretion of external gas. Using our expanded sample that now has the ability to reveal statistically significant trends we explore the potential influence of the galaxy environment on the fueling of Seyfert AGN.

  18. Review of Space VLBI RadioAstron studies of AGN

    NASA Astrophysics Data System (ADS)

    Gurvits, Leonid; Kovalev, Yuri

    2016-07-01

    Space VLBI offers an unrivalled resolution in studies of the AGN phenomena. Since 2011, the Russia-led SVLBI mission RadioAstron conducts observations at 92, 18, 6 and 1.3 cm with baselines an order of magnitude longer than the Earth diameter, therefore offering an order of magnitude "sharper" view at the brightest radio sources than achieved with Earth-based VLBI systems. In our presentation we will review the current status of the RadioAstron's scientific programme. Over the first 4.5 years of the in-orbit operations, the mission achieved successful VLBI detections of extragalactic continuum radio sources at all four observing bands. To date, detections on SVLBI baselines have been obtained for more than 150 AGN's at projected baselines up to 350 000 km (about 28 Earth diameters, ED). The highest resolution achieved is 14 microarcscends from 1.3 cm observations. RadioAstron is an international project; it conducts observations with up to 30 Earth-based radio telescopes located on different continents. We will review results of total intensity and polarisation imaging with extreme angular resolution of blazars and nearby active galaxies. We will also discuss typical and maximum brightness temperatures of blazar cores from the AGN Survey obtained with RadioAstron. Physical implications for the AGN jets formation, magnetic field and emission mechanism will be discussed on the basis of the results obtained to date.

  19. Fast ionized X-ray absorbers in AGNs

    NASA Astrophysics Data System (ADS)

    Fukumura, K.; Tombesi, F.; Kazanas, D.; Shrader, C.; Behar, E.; Contopoulos, I.

    2016-05-01

    We investigate the physics of the X-ray ionized absorbers often identified as warm absorbers (WAs) and ultra-fast outflows (UFOs) in Seyfert AGNs from spectroscopic studies in the context of magnetically-driven accretion-disk wind scenario. Launched and accelerated by the action of a global magnetic field anchored to an underlying accretion disk around a black hole, outflowing plasma is irradiated and ionized by an AGN radiation field characterized by its spectral energy density (SED). By numerically solving the Grad-Shafranov equation in the magnetohydrodynamic (MHD) framework, the physical property of the magnetized disk-wind is determined by a wind parameter set, which is then incorporated into radiative transfer calculations with xstar photoionization code under heating-cooling equilibrium state to compute the absorber's properties such as column density N_H, line-of-sight (LoS) velocity v, ionization parameter ξ, among others. Assuming that the wind density scales as n ∝ r-1, we calculate theoretical absorption measure distribution (AMD) for various ions seen in AGNs as well as line spectra especially for the Fe Kα absorption feature by focusing on a bright quasar PG 1211+143 as a case study and show the model's plausibility. In this note we demonstrate that the proposed MHD-driven disk-wind scenario is not only consistent with the observed X-ray data, but also help better constrain the underlying nature of the AGN environment in a close proximity to a central engine.

  20. Fast Ionized X-ray Absorbers in AGNs

    NASA Astrophysics Data System (ADS)

    Fukumura, K.; Tombesi, F.; Kazanas, D.; Shrader, C.; Behar, E.; Contopoulos, I.

    2015-07-01

    We present a study of X-ray ionization of MHD accretion-disk wind models in an effort to explain the highly-ionized ultra-fast outflows (UFOs) identified as X-ray absorbers recently detected in various sub-classes of Seyfert AGNs. Our primary focus is to show that magnetically-driven outflows are physically plausible candidates to account for the AGN X-ray spectroscopic observations. We calculate its X-ray ionization and the ensuing X-ray absorption line spectra in comparison with an XXM-Newton/EPIC spectrum of the narrow-line Seyfert AGN, PG 1211+143. We find, through identifying the detected features with Fe Kα transitions, that the absorber has a characteristic ionization parameter of log(xi[erg cm/s]) = 5-6 and a hydrogen-equivalent column density on the order of 1e23 cm-2, outflowing at a sub-relativistic velocity of v/c = 0.1-0.2. The best-fit model favors its radial location at R = 200 Rs (Rs is the Schwarzschild radius), with a disk inner truncation radius at Rt = 30Rs. The overall K-shell feature in data is suggested to be dominated by Fe XXV with very little contribution from Fe XXVI and weakly-ionized iron, which is in a good agreement with a series of earlier analysis of the UFOs in various AGNs including PG 1211+143.

  1. First Results from the NuSTAR AGN Physics Program

    NASA Astrophysics Data System (ADS)

    Brenneman, Laura; Fuerst, F.; Matt, G.; Walton, D.; Madejski, G. M.; Marinucci, A.; Elvis, M.; Risaliti, G.; Harrison, F.; Stern, D.; Boggs, S.; Christensen, F.; Craig, W. W.; Zhang, W.; NuSTAR Team

    2013-04-01

    The Nuclear Spectroscopic Telescope Array (NuSTAR, launched June 2012) is revolutionizing our knowledge of the physics at work in active galactic nuclei (AGN). With its high collecting area, focusing optics and low background from 3-79 keV, NASA's newest X-ray observatory is providing an unprecedented look at the spectral and timing properties of AGN in this energy range, which have been notoriously difficult to access. NuSTAR has observed several AGN to date simultaneously with XMM-Newton, Suzaku and/or Swift for the purposes of understanding their coronal properties (e.g., plasma temperature, optical depth) and measuring the spins of their supermassive black holes. We present the first results from these observing campaigns, highlighting the spectral and timing analysis of the bright, nearby AGN IC 4329A, NGC 4151, NGC 1365 and MCG--6-30-15. These are the highest signal-to-noise datasets ever obtained across the 0.2-79 keV energy band for these three sources, allowing us to cleanly deconvolve the X-ray continuum, absorption and reflection components in each galaxy for the first time via time-averaged and time-resolved spectroscopy.

  2. Sexual Freedom Rights for Adolescents? A Rejoinder to Agnes Tellings

    ERIC Educational Resources Information Center

    Steutel, Jan

    2009-01-01

    Agnes Tellings rightly observes that adolescents, if compared with pre-pubescent children, are much more capable of making their own choices and therefore should be granted much more freedom to arrange their own lives. However, the capacity of adolescents to make prudent choices still seems to be below the threshold of competence. Therefore,…

  3. Agnes Mary Clerke: Ever-popular historian of astronomy

    NASA Astrophysics Data System (ADS)

    Brück, M.

    In her day, Agnes Mary Clerke (1842-1907) was the English-speaking world's most highly regarded writer on the rapidly developing science of astrophysics. This account outlines how, without any formal education but with a deep interest in learning, this remarkable woman rose to the admired position she still holds as a leading historian of astronomy and astrophysics.

  4. Understanding AGNs in the Local Universe through Optical Reverberation Mapping

    NASA Astrophysics Data System (ADS)

    Pei, Liuyi

    2016-01-01

    I present the results of observational projects aimed at measuring the mass of the black hole at the center of active galactic nuclei (AGNs) and understanding the structure and kinematics of the broad-line emitting gas within the black hole's sphere of influence.The first project aims to measure the black hole mass in the Kepler-field AGN KA1858. We obtained simultaneous spectroscopic data from the Lick Observatory 3-m telescope using the Kast Double Spectrograph and photometry data from five ground-based telescopes, and used reverberation mapping (RM) techniques to measure the emission-line light curves' lags relative to continuum variations. We obtained lags for H-beta, H-gamma, H-delta, and He II, and obtained the first black hole mass measurement for this object. Our results will serve as a reference point for future studies on relations between black hole mass and continuum variability characteristics using Kepler AGN light curves.The second project, in collaboration with the AGN STORM team, aims to understand the structure and dynamics of the broad line region (BLR) in NGC 5548 in both UV and optical wavelengths. To supplement 6 months of HST UV observations, we obtained simultaneous optical spectroscopic data from six ground-based observatories. We obtained emission-line lags for the optical H-beta and He II lines as well as velocity-resolved lag measurements for H-beta. We also compared the velocity-resolved lags for H-beta to the UV emission lines C IV and Ly-alpha and found similar lag profiles for all three lines.Finally, I will discuss my contributions to two other collaborations in AGN RM. A key component in RM is monitoring continuum variability, which is often done through ground-based photometry. I will present a pipeline that performs aperture photometry on any number of images of an AGN with WCS coordinates and immediately produces relative light curves. This pipeline enables quick looks of AGN variability in real time and has been used in the

  5. A radio view of high-energy emitting AGNs

    NASA Astrophysics Data System (ADS)

    Schulz, Robert Frank

    2016-07-01

    Active galactic nuclei (AGNs) are among the most energetic objects in the Universe. These galaxies that are dominated in part or even throughout the electromagnetic spectrum by emission from their central, compact region. AGNs are extensively studied by multi-wavelength observations. In the standard picture, the main driver of an AGN is a supermassive black hole (SMBH) in its centre that is surrounded by an accretion disk. Perpendicular to the disk, in the vicinity of highly magnetized SMBH relativistic outflows of plasma, so-called jets, can form on either side that can reach far beyond the host galaxy. Only about 10% of all AGNs are dominated by emission from these jets due to relativistic beaming effects and these so-called blazars dominate the extragalactic gamma-ray sky. It is commonly accepted that the low-energy emission (radio to UV/X-ray) is due to synchrotron emission from the jet. The high-energy emission is considered to stem from inverse-Compton scattering of photons on the jet particles, but different sources for these photons are discussed (internal or external to the AGN) and other models for the high-energy emission have also been proposed. The nature of the high-energy emission is strongly linked to the location of the emission region in the jet which requires a detailed understanding of the formation and evolution of jets. Radio observations especially using very long baseline interferometry (VLBI) provide the best way to gain direct information on the intrinsic properties of jets down to sub-pc scales, close to their formation region. In this thesis, I focus on the properties of three different AGNs, IC 310, PKS2004-447, and 3C 111 that belong to the small non-blazar population of gamma-ray-loud AGNs. I study them in detail with a variety of radio astronomical instruments with respect to their high-energy emission and in the context of the large monitoring programmes MOJAVE (Monitoring Of Jets in Active galactic nuclei with VLBA Experiments) and

  6. FCC main fractionator revamps

    SciTech Connect

    Golden, S.W.; Martin, G.R.; Sloley, A.W. )

    1993-03-01

    Structured packing use in fluid catalytic cracker (FCC) main fractionators significantly impacts unit pressure profile. Unit pressure balance links the FCC main fractionator, reactor, regenerator, air compressor and wet gas compressor. Unit pressure balance should be viewed as a design variable when evaluating FCC unit revamps. Depending upon limitations of the particular FCC unit, capacity increases of 12.5% to 22.5% have been achieved without modifications to major rotating equipment, by revamping FCC main fractionators with structured packing. An examination of three FCC main fractionator revamps show improvements to pressure profiles and unit capacity. The three revamps described included a wet gas compressor volume limit; an air blower limitation; and a wet gas compressor motor limitation.

  7. About increase of the large transvere momentum processes fraction in hA interactions at energies 5.10(14) - 10(16) eV according to the data on E.A.S. hadrons

    NASA Technical Reports Server (NTRS)

    Danilova, T. V.; Dubovy, A. G.; Erlykin, A. D.; Nesterova, N. M.; Chubenko, A. P.

    1985-01-01

    The lateral distributions of extensive air showers (EAS) hadrons obtained at Tien-Shan array are compared with the simulations. The simulation data have been treated in the same way as experimental data, including the recording method. The comparison shows that the experimental hadron lateral distributions are wider than simulated ones. On the base of this result the conclusion is drawn that the fraction of processes with large p (perpendicular) increases in hadron-air interactions at energies 5 x 10 to the 14 to 10 to the 16 eV compared with accelerator data in p-p interactions at lower energies.

  8. THE LICK AGN MONITORING PROJECT: REVERBERATION MAPPING OF OPTICAL HYDROGEN AND HELIUM RECOMBINATION LINES

    SciTech Connect

    Bentz, Misty C.; Walsh, Jonelle L.; Barth, Aaron J.; Thornton, Carol E.; Yoshii, Yuzuru; Sakata, Yu; Minezaki, Takeo; Woo, Jong-Hak; Malkan, Matthew A.; Wang, Xiaofeng; Steele, Thea N.; Silverman, Jeffrey M.; Serduke, Frank J. D.; Li, Weidong; Lee, Nicholas; Treu, Tommaso; Street, Rachel A.; Hidas, Marton G.; Hiner, Kyle D.; Greene, Jenny E.

    2010-06-20

    We have recently completed a 64-night spectroscopic monitoring campaign at the Lick Observatory 3 m Shane telescope with the aim of measuring the masses of the black holes in 12 nearby (z < 0.05) Seyfert 1 galaxies with expected masses in the range {approx}10{sup 6}-10{sup 7} M{sub sun} and also the well-studied nearby active galactic nucleus (AGN) NGC 5548. Nine of the objects in the sample (including NGC 5548) showed optical variability of sufficient strength during the monitoring campaign to allow for a time lag to be measured between the continuum fluctuations and the response to these fluctuations in the broad H{beta} emission, which we have previously reported. We present here the light curves for the H{alpha}, H{gamma}, He II {lambda}4686, and He I {lambda}5876 emission lines and the time lags for the emission-line responses relative to changes in the continuum flux. Combining each emission-line time lag with the measured width of the line in the variable part of the spectrum, we determine a virial mass of the central supermassive black hole from several independent emission lines. We find that the masses are generally consistent within the uncertainties. The time-lag response as a function of velocity across the Balmer line profiles is examined for six of the AGNs. We find similar responses across all three Balmer lines for Arp 151, which shows a strongly asymmetric profile, and for SBS 1116+583A and NGC 6814, which show a symmetric response about zero velocity. For the other three AGNs, the data quality is somewhat lower and the velocity-resolved time-lag response is less clear. Finally, we compare several trends seen in the data set against the predictions from photoionization calculations as presented by Korista and Goad. We confirm several of their predictions, including an increase in responsivity and a decrease in the mean time lag as the excitation and ionization level for the species increases. Specifically, we find the time lags of the optical

  9. Faint AGNs at z > 4 in the CANDELS GOODS-S field: looking for contributors to the reionization of the Universe

    NASA Astrophysics Data System (ADS)

    Giallongo, E.; Grazian, A.; Fiore, F.; Fontana, A.; Pentericci, L.; Vanzella, E.; Dickinson, M.; Kocevski, D.; Castellano, M.; Cristiani, S.; Ferguson, H.; Finkelstein, S.; Grogin, N.; Hathi, N.; Koekemoer, A. M.; Newman, J. A.; Salvato, M.

    2015-06-01

    Context. Establishing the number of faint active galactic nuclei (AGNs) at z = 4-6 is crucial to understanding their cosmological importance as main contributors to the reionization of the Universe. Aims: In order to derive the AGN contribution to the cosmological ionizing emissivity we have selected faint AGN candidates at z> 4 in the CANDELS GOODS-South field, which is one of the deepest fields with extensive multiwavelength coverage from Chandra, HST, Spitzer, and various ground-based telescopes. Methods: We have adopted a relatively novel criterion. As a first step, high redshift galaxies are selected in the NIR H band down to very faint levels (H ≤ 27) using reliable photometric redshifts. At z> 4 this corresponds to a selection criterion based on the galaxy rest-frame UV flux. AGN candidates are then picked up from this parent sample if they show X-ray fluxes above a threshold of FX ˜ 1.5 × 10-17 erg cm-2 s-1 (0.5-2 keV), corresponding to a probability of spurious detections of 2 × 10-4 in the deep X-ray 4 Ms Chandra image. Results: We have found 22 AGN candidates at z> 4 and we have derived the first estimate of the UV luminosity function in the redshift interval 4 fraction of ionizing photons from the AGN host galaxies. Both effects could, in principle, significantly reduce the estimated average volume densities and/or ionizing emissivities, especially at the highest

  10. Gamma-ray monitoring of AGN and galactic black hole candidates by the Gamma-Ray Observatory

    NASA Technical Reports Server (NTRS)

    Wheaton, Wm. A.; Ling, James C.; Skelton, R. T.; Harmon, Alan; Fishman, Gerald J.; Meegan, Charles A.; Paciesas, William S.; Rubin, Brad; Wilson, Robert B.; Gruber, Duane E.

    1992-01-01

    The Burst and Transient Spectroscopy Experiment (BATSE) on the Compton Gamma-Ray Observatory has a powerful capability to provide nearly uninterrupted monitoring in the 25 keV-10 MeV range of both AGN and Galactic black hole candidates such as Cygnus X-1, using the occultation of cosmic sources by the Earth. Progress in background modeling indicates that the data accept region, or fit window tau, around the occultation step can be substantially increased over that conservatively assumed in earlier estimates of BATSE's Earth occultation sensitivity. We show samples of large-tau fits to background and source edges. As a result we expect to be able to perform long-term monitoring of Cygnus X-1 and many of the brighter AGN for the duration of the CGRO mission.

  11. Coronal accretion: the power of X-ray emission in AGN

    NASA Astrophysics Data System (ADS)

    Liu, B.-F.; Taam, R. E.; Qiao, E.; Yuan, W.

    2016-02-01

    The optical/UV and X-ray emissions in luminous AGN are commonly believed to be produced in an accretion disk and an embedded hot corona respectively. We explore the possibility that a geometrically thick coronal gas flow, which is supplied by gravitational capture of interstellar medium or stellar wind, condenses partially to a geometrically thin cold disk and accretes via a thin disk and a corona onto the supermassive black hole. We found that for mass supply rates less than about 0.01 (expressed in Eddington units), condensation does not occur and the accretion flow takes the form of a corona/ADAF. For higher mass supply rates, corona gas condenses to the disk. As a consequence, the coronal mass flow rate decreases and the cool mass flow rate increases towards the black hole. Here the thin disk is characterized by the condensation rate of hot gas as it flows towards the black hole. With increase of mass supply rate, condensation becomes more efficient, while the mass flow rate of the coronal gas attains values of order 0.02 in the innermost regions of the disk, which can help to elucidate the production of strong X-ray with respect to the optical and ultraviolet radiation in high luminosity AGN.

  12. Large-scale clustering measurements with photometric redshifts: comparing the dark matter haloes of X-ray AGN, star-forming and passive galaxies at z ≈ 1

    NASA Astrophysics Data System (ADS)

    Georgakakis, A.; Mountrichas, G.; Salvato, M.; Rosario, D.; Pérez-González, P. G.; Lutz, D.; Nandra, K.; Coil, A.; Cooper, M. C.; Newman, J. A.; Berta, S.; Magnelli, B.; Popesso, P.; Pozzi, F.

    2014-10-01

    We combine multi-wavelength data in the AEGIS-XD and C-COSMOS surveys to measure the typical dark matter halo mass of X-ray selected active galactic nuclei (AGN) [LX(2-10 keV) > 1042 erg s- 1] in comparison with far-infrared selected star-forming galaxies detected in the Herschel/PEP survey (PACS Evolutionary Probe; LIR > 1011 L⊙) and quiescent systems at z ≈ 1. We develop a novel method to measure the clustering of extragalactic populations that uses photometric redshift probability distribution functions in addition to any spectroscopy. This is advantageous in that all sources in the sample are used in the clustering analysis, not just the subset with secure spectroscopy. The method works best for large samples. The loss of accuracy because of the lack of spectroscopy is balanced by increasing the number of sources used to measure the clustering. We find that X-ray AGN, far-infrared selected star-forming galaxies and passive systems in the redshift interval 0.6 < z < 1.4 are found in haloes of similar mass, log MDMH/(M⊙ h-1) ≈ 13.0. We argue that this is because the galaxies in all three samples (AGN, star-forming, passive) have similar stellar mass distributions, approximated by the J-band luminosity. Therefore, all galaxies that can potentially host X-ray AGN, because they have stellar masses in the appropriate range, live in dark matter haloes of log MDMH/(M⊙ h-1) ≈ 13.0 independent of their star formation rates. This suggests that the stellar mass of X-ray AGN hosts is driving the observed clustering properties of this population. We also speculate that trends between AGN properties (e.g. luminosity, level of obscuration) and large-scale environment may be related to differences in the stellar mass of the host galaxies.

  13. Heavily reddened quasars at z ˜ 2 in the UKIDSS Large Area Survey: a transitional phase in AGN evolution

    NASA Astrophysics Data System (ADS)

    Banerji, Manda; McMahon, Richard G.; Hewett, Paul C.; Alaghband-Zadeh, Susannah; Gonzalez-Solares, Eduardo; Venemans, Bram P.; Hawthorn, Melanie J.

    2012-12-01

    We present a new sample of purely near-infrared-selected KVega < 16.5 [KAB < 18.4] extremely red [(J - K)Vega > 2.5] quasar candidates at z ˜ 2 from ≃900 deg2 of data in the UKIDSS Large Area Survey (LAS). Five of these are spectroscopically confirmed to be heavily reddened type 1 active galactic nuclei (AGN) with broad emission lines bringing our total sample of reddened quasars from the UKIDSS-LAS to 12 at z = 1.4-2.7. At these redshifts, Hα (6563 Å) is in the K band. However, the mean Hα equivalent width of the reddened quasars is only 10 per cent larger than that of the optically selected population and cannot explain the extreme colours. Instead, dust extinction of AV ˜ 2-6 mag is required to reproduce the continuum colours of our sources. This is comparable to the dust extinctions seen in submillimetre galaxies at similar redshifts. We argue that the AGN are likely being observed in a relatively short-lived breakout phase when they are expelling gas and dust following a massive starburst, subsequently turning into UV-luminous quasars. Some of our quasars show direct evidence for strong outflows (v ˜ 800-1000 km s-1) affecting the Hα line consistent with this scenario. We predict that a larger fraction of reddened quasar hosts are likely to be submillimetre bright compared to the UV-luminous quasar population. We use our sample to place new constraints on the fraction of obscured type 1 AGN likely to be missed in optical surveys. Taken at face value our findings suggest that the obscured fraction depends on quasar luminosity. The space density of obscured quasars is approximately five times that inferred for UV-bright quasars from the Sloan Digital Sky Survey (SDSS) luminosity function at Mi < -30 but seems to drop at lower luminosities even accounting for various sources of incompleteness in our sample. We find that at Mi ˜ -28 for example, this fraction is unlikely to be larger than ˜20 per cent although these fractions are highly uncertain at

  14. Host Galaxy Properties of BAT Hard X-ray Selected AGN

    NASA Astrophysics Data System (ADS)

    Koss, Michael; Mushotzky, Richard; Veilleux, Sylvain; Winter, Lisa

    2010-07-01

    Surveys of AGN taken in the optical, UV, and soft X-rays miss an important population of obscured AGN only visible in the hard X-rays and mid-IR wavelengths. The SWIFT BAT survey in the hard X-ray range (14-195 keV) has provided a uniquely unbiased sample of 246 AGN unaffected by galactic or circumnuclear absorption [1]. Most of the sources in the survey are bright, Seyfert like AGN's with median redshift of 0.03. Of the AGN, 43% are obscured, type II AGN. We obtained 17 nights of imaging of 90 host galaxies of these AGN in 2008 at the Kitt Peak 2.1 m telescope in the SDSS ugriz filters. For the broad line sources we subtracted the AGN contribution using GALFIT. By comparing our sample of AGN to inactive galaxies in the SDSS, we find that AGN are found in the most massive galaxies and are bluer in color than inactive galaxies of comparable stellar mass. We also find a correlation between the point source optical light and hard X-ray luminosity.

  15. Host Galaxy Properties of BAT Hard X-ray Selected AGN

    SciTech Connect

    Koss, Michael; Mushotzky, Richard; Veilleux, Sylvain; Winter, Lisa

    2010-07-15

    Surveys of AGN taken in the optical, UV, and soft X-rays miss an important population of obscured AGN only visible in the hard X-rays and mid-IR wavelengths. The SWIFT BAT survey in the hard X-ray range (14-195 keV) has provided a uniquely unbiased sample of 246 AGN unaffected by galactic or circumnuclear absorption [1]. Most of the sources in the survey are bright, Seyfert like AGN's with median redshift of 0.03. Of the AGN, 43% are obscured, type II AGN. We obtained 17 nights of imaging of 90 host galaxies of these AGN in 2008 at the Kitt Peak 2.1 m telescope in the SDSS ugriz filters. For the broad line sources we subtracted the AGN contribution using GALFIT. By comparing our sample of AGN to inactive galaxies in the SDSS, we find that AGN are found in the most massive galaxies and are bluer in color than inactive galaxies of comparable stellar mass. We also find a correlation between the point source optical light and hard X-ray luminosity.

  16. A NEW INFRARED COLOR CRITERION FOR THE SELECTION OF 0 < z < 7 AGNs: APPLICATION TO DEEP FIELDS AND IMPLICATIONS FOR JWST SURVEYS

    SciTech Connect

    Messias, H.; Afonso, J.; Salvato, M.; Mobasher, B.; Hopkins, A. M.

    2012-08-01

    It is widely accepted that observations at mid-infrared (mid-IR) wavelengths enable the selection of galaxies with nuclear activity, which may not be revealed even in the deepest X-ray surveys. Many mid-IR color-color criteria have been explored to accomplish this goal and tested thoroughly in the literature. Besides missing many low-luminosity active galactic nuclei (AGNs), one of the main conclusions is that, with increasing redshift, the contamination by non-active galaxies becomes significant (especially at z {approx}> 2.5). This is problematic for the study of the AGN phenomenon in the early universe, the main goal of many of the current and future deep extragalactic surveys. In this work new near- and mid-IR color diagnostics are explored, aiming for improved efficiency-better completeness and less contamination-in selecting AGNs out to very high redshifts. We restrict our study to the James Webb Space Telescope wavelength range (0.6-27 {mu}m). The criteria are created based on the predictions by state-of-the-art galaxy and AGN templates covering a wide variety of galaxy properties, and tested against control samples with deep multi-wavelength coverage (ranging from the X-rays to radio frequencies). We show that the colors K{sub s} - [4.5], [4.5] - [8.0], and [8.0] - [24] are ideal as AGN/non-AGN diagnostics at, respectively, z {approx}< 1, 1 {approx}< z {approx}< 2.5, and z {approx}> 2.5-3. However, when the source redshift is unknown, these colors should be combined. We thus develop an improved IR criterion (using K{sub s} and IRAC bands, KI) as a new alternative at z {approx}< 2.5. KI does not show improved completeness (50%-60% overall) in comparison to commonly used Infrared Array Camera (IRAC) based AGN criteria, but is less affected by non-AGN contamination (revealing a >50%-90% level of successful AGN selection). We also propose KIM (using K{sub s} , IRAC, and MIPS 24 {mu}m bands, KIM), which aims to select AGN hosts from local distances to as far

  17. soil organic matter fractionation

    NASA Astrophysics Data System (ADS)

    Osat, Maryam; Heidari, Ahmad

    2010-05-01

    studies were carried out to illustrate the relationship between clay mineral series and organic matter. According to the results the amount of organic carbon increases by decreasing size fractions and reaches to its maximum in <250μ classes, also 2:1 and expanding clays which have the ability to maintain larger amounts of organic carbon were the dominant clay minerals. Chemical fractionation of soil organic matter to humic acid and fulvic acid shows that there is a better correlation between humic acid contents and soil organic matter (R2 = 0.86) than fulvic acid and organic matter (R2=0.5). The amount of humic and fulvic acids varies in different size fractions and reaches to its minimum in the E fraction in all three stages. The relationships between fulvic and humic acids with organic matter content, demonstrating that at the lower organic matter content, humification is slow, thus humic acid content is rather low than the fulvic acid content. By increasing the organic matter content biological activity increases and followed by humification process proceeds so that the humic acid content locates over the fulvic acid content.

  18. Fraction collector for electrophoresis

    NASA Technical Reports Server (NTRS)

    Bier, M.

    1977-01-01

    Rotating-tube electrophoresis apparatus employs rotating jet of eluting buffer to reduce effects of convection during separation. Designed for separation of microorganisms and biological species, system combines gravity/gradient compensating of lumen with buffer flush at fraction outlet to increase separation efficiency.

  19. Suzaku Discovery of Ultra-fast Outflows in Radio-loud AGN

    NASA Astrophysics Data System (ADS)

    Sambruna, Rita M.; Tombesi, F.; Reeves, J.; Braito, V.; Gofford, J.; Cappi, M.

    2010-03-01

    We present the results of an analysis of the 3.5--10.5 keV spectra of five bright Broad-Line Radio Galaxies (BLRGs) using proprietary and archival Suzaku observations. In three sources -- 3C 111, 3C 120, and 3C 390.3 -- we find evidence, for the first time in a radio-loud AGN, for absorption features at observed energies 7 keV and 8--9 keV, with high significance according to both the F-test and extensive Monte Carlo simulations (99% or larger). In the remaining two BLRGs, 3C 382 and 3C 445, there is no evidence for such absorption features in the XIS spectra. If interpreted as due to Fe XXV and/or Fe XXVI K-shell resonance lines, the absorption features in 3C 111, 3C 120, and 3C 390.3 imply an origin from an ionized gas outflowing with velocities in the range v 0.04-0.15c, reminiscent of Ultra-Fast Outflows (UFOs) previously observed in radio-quiet Seyfert galaxies. A fit with specific photoionization models gives ionization parameters log ξ 4--5.6 erg s-1 cm and column densities of NH 1022-23 cm-2, similar to the values observed in Seyferts. Based on light travel time arguments, we estimate that the UFOs in the three BLRGs are located within 20--500 gravitational radii from the central black hole, and thus most likely are connected to disk winds/outflows. Our estimates show that the UFOs mass outflow rate is comparable to the accretion rate and their kinetic energy a significant fraction of the AGN bolometric luminosity, making these outflows significant for the global energetic of these systems, in particular for mechanisms of jet formation.

  20. Biochemical Characterization of Paracoccidioides brasiliensis α-1,3-Glucanase Agn1p, and Its Functionality by Heterologous Expression in Schizosaccharomyces pombe

    PubMed Central

    Villalobos-Duno, Héctor; San-Blas, Gioconda; Paulinkevicius, Maryan; Sánchez-Martín, Yolanda; Nino-Vega, Gustavo

    2013-01-01

    α-1,3-Glucan is present as the outermost layer of the cell wall in the pathogenic yeastlike (Y) form of Paracoccidioides brasiliensis. Based on experimental evidence, this polysaccharide has been proposed as a fungal virulence factor. To degrade α-1,3-glucan and allow remodeling of the cell wall, α-1,3-glucanase is required. Therefore, the study of this enzyme, its encoding gene, and regulatory mechanisms, might be of interest to understand the morphogenesis and virulence process in this fungus. A single gene, orthologous to other fungal α-1,3-glucanase genes, was identified in the Paracoccidioides genome, and labeled AGN1. Transcriptional levels of AGN1 and AGS1 (α-1,3-glucan synthase-encoding gene) increased sharply when the pathogenic Y phase was cultured in the presence of 5% horse serum, a reported booster for cell wall α-1,3-glucan synthesis in this fungus. To study the biochemical properties of P. brasiliensis Agn1p, the enzyme was heterologously overexpressed, purified, and its activity profile determined by means of the degradation of carboxymethyl α-1,3-glucan (SCMG, chemically modified from P. brasiliensis α-1,3-glucan), used as a soluble substrate for the enzymatic reaction. Inhibition assays, thin layer chromatography and enzymatic reactions with alternative substrates (dextran, starch, chitin, laminarin and cellulose), showed that Agn1p displays an endolytic cut pattern and high specificity for SCMG. Complementation of a Schizosaccharomyces pombe agn1Δ strain with the P. brasiliensis AGN1 gene restored the wild type phenotype, indicating functionality of the gene, suggesting a possible role of Agn1p in the remodeling of P. brasiliensis Y phase cell wall. Based on amino acid sequence, P. brasiliensis Agn1p, groups within the family 71 of fungal glycoside hydrolases (GH-71), showing similar biochemical characteristics to other members of this family. Also based on amino acid sequence alignments, we propose a subdivision of fungal GH-71 into at

  1. The stability of QSO/AGN broad emission line clouds

    NASA Astrophysics Data System (ADS)

    Krinsky, I. S.; Puetter, R. C.

    1992-08-01

    Results of a numerical linear stability analysis of QSO/AGN emission-line clouds (ELCs) embedded within a confining hot intercloud medium (HIM) are reported. A first-order linear perturbation analysis reveals two important ionstabilities. The first instability is thermal in nature and arises in the interface region between the HIM and the ELC where thermal convection dominates gas heating; the growth time of the instability is approximately 1000 s, resulting in an ELC evaporation time of about 10 yr. The second instability is dynamic in nature, with the sound wave amplitude growing in response to radiative forces. The growth time of this instability is about 10 exp 6 s and essentially independent of the wavelength. The results suggest that if QSO/AGN ELCs have properties similar to those of the standard ELC model, then the broad-line region is in a constant state of flux in which ELCs continually form, are destroyed, and then re-formed.

  2. Aqueous Fraction of Beta vulgaris Ameliorates Hyperglycemia in Diabetic Mice due to Enhanced Glucose Stimulated Insulin Secretion, Mediated by Acetylcholine and GLP-1, and Elevated Glucose Uptake via Increased Membrane Bound GLUT4 Transporters

    PubMed Central

    Kabir, Ashraf Ul; Samad, Mehdi Bin; Ahmed, Arif; Jahan, Mohammad Rajib; Akhter, Farjana; Tasnim, Jinat; Hasan, S. M. Nageeb; Sayfe, Sania Sarker; Hannan, J. M. A.

    2015-01-01

    Background The study was designed to investigate the probable mechanisms of anti-hyperglycemic activity of B. Vulgaris. Methodology/Principal Findings Aqueous fraction of B. Vulgaris extract was the only active fraction (50mg/kg). Plasma insulin level was found to be the highest at 30 mins after B. Vulgaris administration at a dose of 200mg/kg. B. Vulgaris treated mice were also assayed for plasma Acetylcholine, Glucagon Like Peptide-1 (GLP-1), Gastric Inhibitory Peptide (GIP), Vasoactive Intestinal Peptide, Pituitary Adenylate Cyclase-Activating Peptide (PACAP), Insulin Like Growth Factor-1 (IGF-1), Pancreatic Polypeptides (PP), and Somatostatin, along with the corresponding insulin levels. Plasma Acetylcholine and GLP-1 significantly increased in B. Vulgaris treated animals and were further studied. Pharmacological enhancers, inhibitors, and antagonists of Acetylcholine and GLP-1 were also administered to the test animals, and corresponding insulin levels were measured. These studies confirmed the role of acetylcholine and GLP-1 in enhanced insulin secretion (p<0.05). Principal signaling molecules were quantified in isolated mice islets for the respective pathways to elucidate their activities. Elevated concentrations of Acetylcholine and GLP-1 in B. Vulgaris treated mice were found to be sufficient to activate the respective pathways for insulin secretion (p<0.05). The amount of membrane bound GLUT1 and GLUT4 transporters were quantified and the subsequent glucose uptake and glycogen synthesis were assayed. We showed that levels of membrane bound GLUT4 transporters, glucose-6-phosphate in skeletal myocytes, activity of glycogen synthase, and level of glycogen deposited in the skeletal muscles all increased (p<0.05). Conclusion Findings of the present study clearly prove the role of Acetylcholine and GLP-1 in the Insulin secreting activity of B. Vulgaris. Increased glucose uptake in the skeletal muscles and subsequent glycogen synthesis may also play a part in

  3. Multidimensional Separation Using HILIC and SCX Pre-fractionation for RP LC-MS/MS Platform with Automated Exclusion List-based MS Data Acquisition with Increased Protein Quantification

    PubMed Central

    Zhou, Yu; Meng, Zhen; Edman-Woolcott, Maria; Hamm-Alvarez, Sarah F; Zandi, Ebrahim

    2015-01-01

    Liquid chromatography–mass spectrometry (LC-MS) based proteomics is one of the most widely used analytical platforms for global protein discovery and quantification. One of the challenges is the difficulty of identifying low abundance biomarker proteins from limited biological samples. Extensive fractionation could expand proteomics dynamic range, however, at the cost of high sample and time consumption. Extensive fractionation would increase the sample need and the labeling cost. Also quantitative proteomics depending on high resolution MS have the limitation of spectral acquisition speed. Those practical problems hinder the in-depth quantitative proteomics analysis such as tandem mass tag (TMT) experiments. We found the joint use of hydrophilic interaction liquid chromatography (HILIC) and strong cation exchange Chromatography (SCX) prefractionation at medium level could improve MS/MS efficiency, increase proteome coverage, shorten analysis time and save valuable samples. In addition, we scripted a program, Exclusion List Convertor (ELC), which automates and streamlines data acquisition workflow using the precursor ion exclusion (PIE) method. PIE reduces redundancy of high abundance MS/MS analyses by running replicates of the sample. The precursor ions detected in the initial run(s) are excluded for MS/MS in the subsequent run. We compared PIE methods with standard data dependent acquisition (DDA) methods running replicates without PIE for their effectiveness in quantifying TMT-tagged peptides and proteins in mouse tears. We quantified a total of 845 proteins and 1401 peptides using the PIE workflow, while the DDA method only resulted in 347 proteins and 731 peptides. This represents a 144% increase of protein identifications as a result of PIE analysis. PMID:26807013

  4. A Unified View of X-ray Absorbers in AGNs and XRBs with MHD Winds

    NASA Astrophysics Data System (ADS)

    Fukumura, Keigo; Kazanas, Demosthenes; Shrader, Chris R.; Tombesi, Francesco; Behar, Ehud; Contopoulos, John

    2016-01-01

    The presence of UV and X-ray absorbers (aka. warm absorbers or WAs) has been long known for decades from extensive spectroscopic studies across diverse AGN populations such as nearby Seyfert galaxies and distant quasars. Furthermore, another class of seemingly distinct type of absorbers, ultra-fast outflows or UFOs, is becoming increasingly known today. Nonetheless, a physical identification of such absorbers, such as geometrical property and physical conditions, is very elusive to date despite the recent state-of-the-art observations. We develop a coherent scenario in which the detected absorbers are driven primarily (if not exclusively) by the action of global magnetic fields originating from a black hole accretion disk. In the context of MHD disk-wind of density profile of n~1/r, it is found that the properties of the observed WAs/UFOs are successfully described assuming a characteristic SED. As a case study, we analyze PG1211+143 and GRO J1655-40 to demonstrate that our wind model can systematically unify apparently diverse absorbers in both AGNs and XRBs in terms of explaining their global behavior as well as individual spectral lines.

  5. Four Dual AGN Candidates Observed with the VLBA

    NASA Astrophysics Data System (ADS)

    Gabányi, K. É.; An, T.; Frey, S.; Komossa, S.; Paragi, Z.; Hong, X.-Y.; Shen, Z.-Q.

    2016-08-01

    According to hierarchical structure formation models, merging galaxies are expected to be seen in different stages of coalescence. However, there are currently no straightforward observational methods to either select or to confirm a large number of dual active galactic nucleus (AGN) candidates. Most attempts involve obtaining a better understanding of double-peaked narrow emission line sources, in order to distinguish the objects for which the emission lines originate from narrow-line kinematics or jet-driven outflows, from those which might harbor dual AGNs. We observed four such candidate sources with the Very Long Baseline Array (VLBA), at 1.5 GHz with a ∼10 mas angular resolution, for which the spectral profiles of AGN optical emission suggested the existence of dual AGNs. In SDSS J210449.13–000919.1 and SDSS J23044.82–093345.3 the radio structures are aligned with the optical emission features, thus the double-peaked emission lines might be the results of jet-driven outflows. In the third detected source SDSS J115523.74+150756.9, the radio structure is less extended and is oriented nearly perpendicular to the position angle derived from optical spectroscopy. The fourth source remained undetected with the VLBA, but it was imaged with the Very Large Array at arcsec resolution a few months before our observations, suggesting the existence of an extended radio structure. We did not detect two radio-emitting cores in any of the four sources, a convincing signature of duality.

  6. Observational aspects of AGN jets at high energy

    NASA Astrophysics Data System (ADS)

    Kataoka, Jun

    2015-03-01

    For the last two decades, significant and dramatic progress has been made in understanding astrophysical jet sources, particularly in the X-ray and gamma-ray energy bands. For example, the Chandra X-ray observatory reveals a number of AGN jets extending from kpc to Mpc scales. More recently, the Fermi Gamma-ray Space Telescopes launched in 2008 started monitoring the gamma-ray sky with excellent sensitivity of about ten times greater than that of EGRET onboard CGRO, and has detected more than 2,000 sources (mostly AGNs) as of 2014. Moreover, Fermi-LAT has discovered gamma-ray emissions not only from blazars but from a dozen radio galaxies not previously known to emit gamma-rays. Closer to home, the Fermi-bubbles were discovered to extend 50 degrees above and below the Galactic center. These large scale diffuse gamma-ray structures are similar in structure to AGN lobes such as those seen in Cen A and provide evidence for past activity in our Galactic center. In this review, I will first summarize recent highlights of large scale jets in radio galaxies, specifically resolved by the Chandra X-ray observatory. Next I will move on to the gamma-ray sky to present some highlights from Fermi-LAT observations of ``misaligned'' blazars, namely radio galaxies. I will discuss a unification scheme connecting blazars and misaligned radio galaxies. In the last part, I will also briefly comment on recent multiband observations of the Fermi-bubble and possible impacts on the AGN jet physics in the near future.

  7. X-ray AGN Clustering, Bias & Accretion mode

    NASA Astrophysics Data System (ADS)

    Plionis, Manolis; Koutoulidis, Lazaros; Georgantopoulos, Ioannis; Fanidakis, Nikolaos

    2012-09-01

    We present the spatial clustering properties of 1466 X-ray selected AGN compiled from the Chandra CDF-N, CDF-S, eCDF-S, COSMOS and AEGIS fields in the 0.5-8 keV band. The X-ray sources span the redshift interval 0AGN bias and the corresponding dark-matter host halo mass, are significantly higher than the corresponding values of optically selected AGN (at the same redshifts. The redshift evolution of the X-ray selected AGN bias indicates, in agreement with other recent studies, that a unique dark-matter halo mass does not fit well the bias at all the different redshifts probed. Furthermore, we investigate if there is a dependence of the clustering strength on X-ray luminosity, applying a procedure to disentangle the dependence of clustering on redshift. We find indications for a positive dependence of the clustering length on X-ray luminosity, in the sense that the more luminous sources have a larger clustering length and hence a higher dark-matter halo mass.

  8. Alignment of Stellar and AGN Accretion Disks from SDSS Data

    NASA Astrophysics Data System (ADS)

    Lagos, Claudia del P.; Padilla, Nelson D.; Strauss, Michael A.; Hao, Lei

    2010-05-01

    Lagos, Padilla & Cora (2009) show that if alignments between the galaxy kinematics and the AGN system were to occur, massive galaxies should host BHs with high spin values, regardless of the detailed physics of the BH. Since the BH spin regulates the mass-to-energy conversion (Marconi et al. 2004) and possibly the existence of radio jets (Sikora et al. 2007), this study has a strong impact in our understanding of galaxy formation.

  9. Near-UV Snapshot Survey of Low Luminosity AGNs

    NASA Astrophysics Data System (ADS)

    Gonzalez-Delgado, Rosa

    2005-07-01

    Low-luminosity active galactic nuclei {LLAGNs} comprise 30% of all bright galaxies {B<12.5} and are the most common type of AGN. These include low-luminosity Seyfert galaxies, LINERs, and transition-type objects {TOs, also called weak-[OI] LINERs}. What powers them is still at the forefront of AGN research. To unveil the nature of the central source we propose a near-UV snapshot survey of 50 nearby LLAGNs using ACS/HRC and the filter {F330W}, a configuration which is optimal to detect faint star forming regions around their nuclei. These images will complement optical and near-IR images available in the HST archive, providing a panchromatic atlas of the inner regions of these galaxies, which will be used to study their nuclear stellar population. Our main goals are to: 1} Investigate the presence of nuclear unresolved sources that can be attributed to an AGN; 2} Determine the frequency of nuclear and circumnuclear stellar clusters, and whether they are more common in Transition Objects {TOs} than in LINERs; 3} Characterize the sizes, colors, luminosities, masses and ages of these clusters; 4} Derive the luminosity function of star clusters and study their evaporation over time in the vicinity of AGNs. Finally, the results of this project will be combined with those of a previous similar one for Seyfert galaxies in order to compare the nature of the nuclear sources and investigate if there could be an evolution from Seyferts to TOs and LINERs. By adding UV images to the existing optical and near-IR ones, this project will also create an extremely valuable database for astronomers with a broad range of scientific interests.

  10. Cadenced IRAC Monitoring of Infrared-Variable AGNs, Part II

    NASA Astrophysics Data System (ADS)

    Ashby, Matthew; Fouesneau, Morgan; Hora, Joseph; Krick, Jessica; Smith, Howard; Surace, Jason

    2008-03-01

    We have analyzed IRAC imaging data from all 97 Spitzer visits to a very well-studied field, the IRAC Dark Calibration Field (IRAC-CF) near the north ecliptic pole. With this extensive dataset we have already identified a unique sample of 30 IR-variable galaxies which we are now working to characterize with respect to variability amplitudes and timescales, panchromatic SEDs, and host morphologies, among other quantities. Unfortunately, the continual change in spacecraft roll angle means that our sources are typically observed for at most six months at a time by each IRAC FOV in succession -- in other words, the visibility windows are exactly out of phase. Thus the existing data, despite the fact that they extend over more than four years, present large, unavoidable gaps that frustrate the time-delay analysis we wish to perform on exactly the timescales known to be common in active galaxies. This has only changed beginning in 2007 July: since that time cadenced IRAC observations have been carried out in synchrony with the IRAC-CF dark-calibration observations as part of our approved Cycle-4 program (PID 40553). Here we are proposing to continue this successful AGN monitoring campaign until the end of the cryogenic mission. The resulting timelines (covering 1500 days thus far and expected to run ultimately to some 2200+ days), will be a unique legacy of the Spitzer mission. This dataset, especially for the sizable, unbiased AGN sample we now have, holds unique promise for measuring the colors and temperatures of IR-varying AGN, and will have much to say about the underlying physical models of the infrared AGN emission. Accordingly we ask for just 8 h to gather IRAC photometry in the temporal gaps that would otherwise accrue in Cycle 5.

  11. Clustering of ROSAT All-Sky Survey AGNs Through Cross-Correlation Functions

    NASA Astrophysics Data System (ADS)

    Krumpe, Mirko; Miyaji, Takamitsu; Coil, Alison

    2010-07-01

    We investigate the clustering propertiesof ~1550 low-redshift broad-line AGNs detected in the ROSAT All-Sky Survey (RASS) through a cross-correlation function (CCF) with ~46000 Luminous Red Galaxies (LRGs) in the Sloan Digital Sky Survey (SDSS). Using this approach, we avoid small-number statistics and systematic errors caused by the variation of the Galactic absorption compared to a direct measurement of the AGN auto-correlation function (ACF). We compute the ACF of low-z RASS-AGN based on the CCF for the total X-ray sample ( = 0.25) and found a correlation length of r0 = 4.3-0.4+0.4 h-1 Mpc. Furthermore, we discovered an X-ray luminosity dependence of the clustering signal, i.e. high luminosity AGN cluster stronger than low luminosity AGN. We have also applied a Halo Occupation Distribution (HOD) model directly to our AGN-LRG CCF.

  12. Suzaku Observations of AGN and Synergy with GLAST

    SciTech Connect

    Kataoka, Jun; Takahashi, Tad; Madejski, Greg; /KIPAC, Menlo Park

    2007-10-29

    In next five years, dramatic progress is anticipated for the AGN studies, as we have two important missions to observe celestial sources in the high energy regime: GLAST and Suzaku. Suzaku is the 5th Japanese X-ray astronomy satellite which was successfully launched in July 2005. It carries four X-ray sensitive imaging CCD cameras (0.2-12 keV) located in the focal planes of X-ray telescope, and a non-imaging, collimated hard X-ray detector, which extends the bandpass of the observatory to include the 10-600 keV range. Simultaneous monitoring observations by the two instruments (GLAST and Suzaku) will be particularly valuable for variable radio-loud AGN, allowing the cross-correlations of time series as well as detailed modeling of the spectral evolution between the X-ray and gamma-ray energy bands. In this paper, we show early highlights from Suzaku observations of radio-loud AGNs, and discuss what we can do with GLAST in forthcoming years.

  13. Probing the central parsecs of AGN using Faraday Rotation

    NASA Astrophysics Data System (ADS)

    Zavala, R. T.; Taylor, G. B.

    2002-05-01

    A broad frequency range and low instrumental polarization makes the Very Long Baseline Array (VLBA) an ideal instrument for studying polarimetry at sub-milliarcsecond resolution. To take advantage of these unique capabilities we have conducted a multi-frequency polarization survey of 40 radio-loud AGN (Quasars, BL Lacs, and radio galaxies). Our aim is to use Faraday Rotation Measures (RMs) as a probe of the central 1-50 parsecs of these objects. The RM is produced by the line of sight magnetic field weighted by the electron density. Using the electron density established through spectral line diagnostics a magnetic field strength and topology can be estimated within a few parsecs of the central engines of these AGN. The observations for the survey are complete, and we present the first results for 8 quasars, 5 BL Lacs, and 4 radio galaxies. The magnitudes for the RMs range from several thousand rad m-2 in the quasars and radio galaxies to a few hundred rad m-2 in the BL Lac objects. These values are in agreement with the basic ideas of the unified model for AGN. We also observe variations in the RM on small spatial (< ~ 1 pc) in radio galaxies and quasars; and short time scales ( ~ 6 months) in the quasars 3C 273 and 3C 279. R.T.Z. gratefully acknowledges support from a pre-doctoral research appointment at NRAO and from the New Mexico Alliance for Graduate Education and the Professiorate through NSF grant HRD-0086701.

  14. Doppler disc tomography applied to low-mass AGN spin

    NASA Astrophysics Data System (ADS)

    Middleton, Matthew J.; Ingram, Adam R.

    2015-01-01

    Doppler tomography can provide a powerful means of determining black hole spin when our view to the central regions are revealed and obscured by optically thick orbiting material, and can provide an independent estimate that does not suffer as many degeneracies as traditional methods. For low-mass active galactic nuclei (AGN), time-dependent obscuration is expected to leave a signature in the changing spectrum of the disc emission which extends into the soft X-ray bandpass. We create a spectral model incorporating Doppler tomography and apply it to the case of the low-mass (8 × 105 M⊙) AGN, RX J1301.9+2747 which shows unusual timing properties in the form of short-lived flares that we argue are best explained by the orbit of a window through an optically thick wind. Modelling the phase-resolved spectrum over the course of the highest data quality flare indicates a very low spin even when we relax our constraints. This is the lowest mass AGN for which a spin has been measured and the first via this technique. We note that, as the mass and spin are very low, this appears to favour supermassive black hole (SMBH) growth by chaotic rather than constant accretion.

  15. The synthesis and characterization of Ag-N dual-doped p-type ZnO: experiment and theory.

    PubMed

    Duan, Li; Wang, Pei; Yu, Xiaochen; Han, Xiao; Chen, Yongnan; Zhao, Peng; Li, Donglin; Yao, Ran

    2014-03-01

    Ag-N dual-doped ZnO films have been fabricated by a chemical bath deposition method. The p-type conductivity of the dual-doped ZnO:(Ag, N) is stable over a long period of time, and the hole concentration in the ZnO:(Ag, N) is much higher than that in mono-doped ZnO:Ag or ZnO:N. We found that this is because AgZn-NO complex acceptors can be formed in ZnO:(Ag, N). First-principles calculations show that the complex acceptors generate a fully occupied band above the valance band maximum, so the acceptor levels become shallower and the hole concentration is increased. Furthermore, the binding energy of the Ag-N complex in ZnO is negative, so ZnO:(Ag, N) can be stable. These results indicate that the Ag-N dual-doping may be expected to be a potential route to achieving high-quality p-type ZnO for use in a variety of devices. PMID:24448605

  16. Clustering, Cosmology and a New Era of Black Hole Demographics: The Conditional Luminosity Function of AGNs

    NASA Astrophysics Data System (ADS)

    Ballantyne, David R.

    2016-04-01

    Deep X-ray surveys have provided a comprehensive and largely unbiased view of AGN evolution stretching back to z˜5. However, it has been challenging to use the survey results to connect this evolution to the cosmological environment that AGNs inhabit. Exploring this connection will be crucial to understanding the triggering mechanisms of AGNs and how these processes manifest in observations at all wavelengths. In anticipation of upcoming wide-field X-ray surveys that will allow quantitative analysis of AGN environments, we present a method to observationally constrain the Conditional Luminosity Function (CLF) of AGNs at a specific z. Once measured, the CLF allows the calculation of the AGN bias, mean dark matter halo mass, AGN lifetime, halo occupation number, and AGN correlation function - all as a function of luminosity. The CLF can be constrained using a measurement of the X-ray luminosity function and the correlation length at different luminosities. The method is demonstrated at z ≈0 and 0.9, and clear luminosity dependence in the AGN bias and mean halo mass is predicted at both z. The results support the idea that there are at least two different modes of AGN triggering: one, at high luminosity, that only occurs in high mass, highly biased haloes, and one that can occur over a wide range of halo masses and leads to luminosities that are correlated with halo mass. This latter mode dominates at z<0.9. The CLFs for Type 2 and Type 1 AGNs are also constrained at z ≈0, and we find evidence that unobscured quasars are more likely to be found in higher mass halos than obscured quasars. Thus, the AGN unification model seems to fail at quasar luminosities.

  17. let-7 Overexpression Leads to an Increased Fraction of Cells in G2/M, Direct Down-regulation of Cdc34, and Stabilization of Wee1 Kinase in Primary Fibroblasts*S⃞

    PubMed Central

    Legesse-Miller, Aster; Elemento, Olivier; Pfau, Sarah J.; Forman, Joshua J.; Tavazoie, Saeed; Coller, Hilary A.

    2009-01-01

    microRNAs play a critically important role in a wide array of biological processes including those implicated in cancer, neuro-degenerative and metabolic disorders, and viral infection. Although we have begun to understand microRNA biogenesis and function, experimental demonstration of their functional effects and the molecular mechanisms by which they function remains a challenge. Members of the let-7/miR-98 family play a critical role in cell cycle control with respect to differentiation and tumorigenesis. In this study, we show that exogenous addition of pre-let-7 in primary human fibroblasts results in a decrease in cell number and an increased fraction of cells in the G2/M cell cycle phase. Combining microarray techniques with DNA sequence analysis to identify potential let-7 targets, we discovered 838 genes with a let-7 binding site in their 3′-untranslated region that were down-regulated upon overexpression of let-7b. Among these genes is cdc34, the ubiquitin-conjugating enzyme of the Skp1/cullin/F-box (SCF) complex. Cdc34 protein levels are strongly down-regulated by let-7 overexpression. Reporter assays demonstrated direct regulation of the cdc34 3′-untranslated region by let-7. We hypothesized that low Cdc34 levels would result in decreased SCF activity, stabilization of the SCF target Wee1, and G2/M accumulation. Consistent with this hypothesis, small interfering RNA-mediated down-regulation of Wee1 reversed the G2/M phenotype induced by let-7 overexpression. We conclude that Cdc34 is a functional target of let-7 and that let-7 induces down-regulation of Cdc34, stabilization of the Wee1 kinase, and an increased fraction of cells in G2/M in primary fibroblasts. PMID:19126550

  18. Statistical Analysis of the Long Baseline Variability Properties of a Large Gamma-Ray Selected Blazar AGN Sample

    NASA Astrophysics Data System (ADS)

    Shrader, Chris R.

    2013-06-01

    The Fermi Gamma-Ray Space Telescope has cataloged over 1800 gamma-ray (>100 MeV) point sources of which more than 1100 are identified with AGN. These AGN, and a large number of unidentified high-latitude objects of which a large fraction are also likely AGN, are predominantly representative of the radio-loud “blazar” subclass. The emission from these objects is well known to be beaming dominated and is almost always variable, often exhibiting high-amplitude flaring. To date there have been numerous studies of individual objects including multi-wavelength campaigns in some cases including parsec-scale radio jet morphological study. Collectively, this has led to new insight in to our understanding of the blazar phenomena and jet propagation in general. However, there remains a dearth of information on the collective variability characteristics of the population as a statistical ensemble. What, for example, are the distributions of flare amplitudes, durations, temporal profiles and recurrence histories among the gamma-ray blazar subclasses? Given the unprecedented sky coverage of Fermi - the full sky is observed approximately every two orbits leading to an approximate one part in 6 monitoring duty cycle for any point on the sky - we have begun to explore this issue. A light curve database compiled and maintained (weekly) by the Fermi Science Support Center contains flux histories for every source in the Fermi 2FGL catalog. In this contribution, we present our analysis of the statistical properties of the high-latitude component of this light curve database.

  19. Cycling of the powerful AGN in MS 0735.6+7421 and the duty cycle of radio AGN in clusters

    NASA Astrophysics Data System (ADS)

    Vantyghem, A. N.; McNamara, B. R.; Russell, H. R.; Main, R. A.; Nulsen, P. E. J.; Wise, M. W.; Hoekstra, H.; Gitti, M.

    2014-08-01

    We present an analysis of deep Chandra X-ray observations of the galaxy cluster MS 0735.6+7421, which hosts the most energetic radio active galactic nucleus (AGN) known. Our analysis has revealed two cavities in its hot atmosphere with diameters of 200-240 kpc. The total cavity enthalpy, mean age, and mean jet power are 9 × 1061 erg, 1.6 × 108 yr, and 1.7 × 1046 erg s-1, respectively. The cavities are surrounded by nearly continuous temperature and surface brightness discontinuities associated with an elliptical shock front of Mach number 1.26 (1.17-1.30) and age of 1.1 × 108 yr. The shock has injected at least 4 × 1061 erg into the hot atmosphere at a rate of 1.1 × 1046 erg s-1. A second pair of cavities and possibly a second shock front are located along the radio jets, indicating that the AGN power has declined by a factor of 30 over the past 100 Myr. The multiphase atmosphere surrounding the central galaxy is cooling at a rate of 40 M⊙yr-1, but does not fuel star formation at an appreciable rate. In addition to heating, entrainment in the radio jet may be depleting the nucleus of fuel and preventing gas from condensing out of the intracluster medium. Finally, we examine the mean time intervals between AGN outbursts in systems with multiple generations of X-ray cavities. We find that, like MS0735, their AGN rejuvenate on a time-scale that is approximately 1/3 of their mean central cooling time-scales, indicating that jet heating is outpacing cooling in these systems.

  20. Highly variable AGN from the XMM-Newton slew survey

    NASA Astrophysics Data System (ADS)

    Strotjohann, N. L.; Saxton, R. D.; Starling, R. L. C.; Esquej, P.; Read, A. M.; Evans, P. A.; Miniutti, G.

    2016-07-01

    Aims: We investigate the properties of a variability-selected complete sample of active galactic nuclei (AGN) in order to identify the mechanisms which cause large amplitude X-ray variability on timescales of years. Methods: A complete sample of 24 sources was constructed, from AGN which changed their soft X-ray luminosity by more than one order of magnitude over 5-20 years between ROSAT observations and the XMM-Newton slew survey. Follow-up observations were obtained with the Swift satellite. We analysed the spectra of these AGN at the Swift and XMM observation epochs, where six sources had continued to display extreme variability. Multiwavelength data are used to calculate black hole masses and the relative X-ray brightness αOX. Results: After removal of two probable spurious sources, we find that the sample has global properties which differ little from a non-varying control sample drawn from the wider XMM-slew/ROSAT/Veron sample of all secure AGN detections. A wide range of AGN types are represented in the varying sample. The black hole mass distributions for the varying and non-varying sample are not significantly different. This suggests that long timescale variability is not strongly affected by black hole mass. There is marginal evidence that the variable sources have a lower redshift (2σ) and X-ray luminosity (1.7σ). Apart from two radio-loud sources, the sample sources have normal optical-X-ray ratios (αOX) when at their peak but are X-ray weak during their lowest flux measurements. Conclusions: Drawing on our results and other studies, we are able to identify a variety of variability mechanisms at play: tidal disruption events, jet activity, changes in absorption, thermal emission from the inner accretion disc, and variable accretion disc reflection. Little evidence for strong absorption is seen in the majority of the sample and single-component absorption can be excluded as the mechanism for most sources.

  1. VizieR Online Data Catalog: Gamma-ray AGN type determination (Hassan+, 2013)

    NASA Astrophysics Data System (ADS)

    Hassan, T.; Mirabal, N.; Contreras, J. L.; Oya, I.

    2013-11-01

    In this paper, we employ Support Vector Machines (SVMs) and Random Forest (RF) that embody two of the most robust supervised learning algorithms available today. We are interested in building classifiers that can distinguish between two AGN classes: BL Lacs and FSRQs. In the 2FGL, there is a total set of 1074 identified/associated AGN objects with the following labels: 'bzb' (BL Lacs), 'bzq' (FSRQs), 'agn' (other non-blazar AGN) and 'agu' (active galaxies of uncertain type). From this global set, we group the identified/associated blazars ('bzb' and 'bzq' labels) as the training/testing set of our algorithms. (2 data files).

  2. The sharpest view of the local AGN population at mid-infrared wavelengths

    NASA Astrophysics Data System (ADS)

    Asmus, Daniel; Hönig, Sebastian F.; Gandhi, Poshak; Smette, Alain; Duschl, Wolfgang J.

    2014-07-01

    We present the largest mid-infrared (MIR) atlas of active galactic nuclei at sub-arcsec spatial scales containing 253 objects with a median redshift of 0.016. It comprises all available ground-based high-angular resolution MIR observations performed to date with 8-meter class telescopes and includes 895 photometric measurements. All types of AGN are present in the atlas, which also includes 80 per cent of the 9-month BAT AGN sample. Therefore, this atlas and its subsamples are very well-suited for AGN unification studies. A first application of the atlas is the extension of the MIR-X-ray luminosity correlation for AGN.

  3. Linking X-ray AGN with dark matter halos: a model compatible with AGN luminosity function and large-scale clustering properties

    NASA Astrophysics Data System (ADS)

    Hütsi, Gert; Gilfanov, Marat; Sunyaev, Rashid

    2014-01-01

    Aims: Our goal is to find a minimalistic model that describes the luminosity function and large-scale clustering bias of X-ray-selected active galactic nuclei in the general framework of the concordance ΛCDM model. Methods: We assume that a simple population-averaged scaling relation between the AGN X-ray luminosity LX and the host dark matter halo mass Mh exists. With such a relation, the AGN X-ray luminosity function can be computed from the halo mass function. Using the concordance ΛCDM halo mass function for the latter, we obtain the Mh - LX relation required to match the redshift-dependent AGN X-ray luminosity function known from X-ray observations. Results: We find that with a simple power-law-scaling Mh ∝ LΓ(z), our model can successfully reproduce the observed X-ray luminosity function. Furthermore, we automatically obtain predictions for the large-scale AGN clustering amplitudes and their dependence on the luminosity and redshift, which seem to be compatible with AGN clustering measurements. Our model also includes the redshift-dependent AGN duty cycle, which peaks at the redshift z ≃ 1, and its peak value is consistent with unity, suggesting that on average there is no more than one AGN per dark matter halo. For a typical X-ray-selected AGN at z ~ 1, our best-fit Mh - LX scaling implies low Eddington ratio LX/LEdd ~ 10-4 - 10-3 (2-10 keV band, no bolometric correction applied) and correspondingly high mass-growth e-folding times, suggesting that typical X-ray AGN are dominantly fueled via relatively inefficient "hot-halo" accretion mode.

  4. Mapping the average AGN accretion rate in the SFR-M* plane for Herschel-selected galaxies at 0 < z ≤ 2.5

    NASA Astrophysics Data System (ADS)

    Delvecchio, I.; Lutz, D.; Berta, S.; Rosario, D. J.; Zamorani, G.; Pozzi, F.; Gruppioni, C.; Vignali, C.; Brusa, M.; Cimatti, A.; Clements, D. L.; Cooray, A.; Farrah, D.; Lanzuisi, G.; Oliver, S.; Rodighiero, G.; Santini, P.; Symeonidis, M.

    2015-05-01

    We study the relation of AGN accretion, star formation rate (SFR) and stellar mass (M*) using a sample of ≈8600 star-forming galaxies up to z = 2.5 selected with Herschel imaging in the GOODS and COSMOS fields. For each of them we derive SFR and M*, both corrected, when necessary, for emission from an active galactic nucleus (AGN), through the decomposition of their spectral energy distributions (SEDs). About 10 per cent of the sample are detected individually in Chandra observations of the fields. For the rest of the sample, we stack the X-ray maps to get average X-ray properties. After subtracting the X-ray luminosity expected from star formation and correcting for nuclear obscuration, we derive the average AGN accretion rate for both detected sources and stacks, as a function of M*, SFR and redshift. The average accretion rate correlates with SFR and with M*. The dependence on SFR becomes progressively more significant at z > 0.8. This may suggest that SFR is the original driver of these correlations. We find that average AGN accretion and star formation increase in a similar fashion with offset from the star-forming `main-sequence'. Our interpretation is that accretion on to the central black hole and star formation broadly trace each other, irrespective of whether the galaxy is evolving steadily on the main-sequence or bursting.

  5. Constraints on Feedback in the Local Universe: The Relation Between Star Formation and AGN Activity in Early Type Galaxies

    NASA Astrophysics Data System (ADS)

    Vaddi, Sravani; O'Dea, Christopher P.; Baum, Stefi Alison

    2016-01-01

    We address the relation between star formation and AGN activity in a sample of 231 nearby (0.0002 < z < 0.0358) early type galaxies by carrying out a multi-wavelength study using archival observations in the UV, IR and radio. Our results indicate that early type galaxies in the current epoch are rarely powerful AGNs, with P < 1022 WHz-1 for a majority of the galaxies. Only massive galaxies are capable of hosting powerful radio sources while less massive galaxies are hosts to lower radio power sources. Evidence of ongoing star formation is seen in approximately 7% of the sample. The SFR of these galaxies is less than 0.1 M⊙yr-1. They also tend to be radio faint (P < 1022 WHz-1). There is a nearly equal fraction of star forming galaxies in radio faint (P < 1022 WHz-1) and radio bright galaxies (P ≥ 1022 WHz-1) suggesting that both star formation and radio mode feedback are constrained to be very low in our sample. We notice that our galaxy sample and the Brightest Cluster Galaxies (BCGs) follow similar trends in radio power versus SFR. This may be produced if both radio power and SFR are related to stellar mass.

  6. Constraints on Feedback in the Local Universe: The Relation between Star Formation and AGN Activity in Early-type Galaxies

    NASA Astrophysics Data System (ADS)

    Vaddi, Sravani; O'Dea, Christopher P.; Baum, Stefi A.; Whitmore, Samantha; Ahmed, Rabeea; Pierce, Katherine; Leary, Sara

    2016-02-01

    We address the relation between star formation and active galactic nucleus (AGN) activity in a sample of 231 nearby (0.0002 < z < 0.0358) early-type galaxies by carrying out a multi-wavelength study using archival observations in the UV, IR, and radio. Our results indicate that early-type galaxies in the current epoch are rarely powerful AGNs, with P\\lt {10}22 {{WHz}}-1 for a majority of the galaxies. Only massive galaxies are capable of hosting powerful radio sources while less massive galaxies are hosts to lower radio power sources. Evidence of ongoing star formation is seen in approximately 7% of the sample. The star formation rate (SFR) of these galaxies is less than 0.1 M⊙ yr-1. They also tend to be radio faint (P\\lt {10}22 {{WHz}}-1). There is a nearly equal fraction of star-forming galaxies in radio faint (P\\lt {10}22 {{WHz}}-1) and radio bright galaxies (P≥slant {10}22 {{WHz}}-1) suggesting that both star formation and radio mode feedback are constrained to be very low in our sample. We notice that our galaxy sample and the Brightest Cluster Galaxies follow similar trends in radio power versus SFR. This may be produced if both radio power and SFR are related to stellar mass.

  7. VizieR Online Data Catalog: ASCA AGN optical identifications (Akiyama+, 2003)

    NASA Astrophysics Data System (ADS)

    Akiyama, M.; Ueda, Y.; Ohta, K.; Takahashi, T.; Yamada, T.

    2003-10-01

    We present the results of optical spectroscopic identifications of a bright subsample of 2-10keV hard X-ray-selected sources from the ASCA Medium Sensitivity Survey in the northern sky (AMSSn). The flux limit of the subsample is 3x10-13erg/s/cm2 in the 2-10keV band. All but one of the 87 hard X-ray-selected sources are optically identified, with AGNs (including broad-line AGNs, narrow-line AGNs, and three BL Lac objects), seven clusters of galaxies, and one galactic star. It is the largest complete sample of hard X-ray-selected AGNs at the bright flux limit. Amounts of absorption to their nuclei are estimated to be hydrogen column densities (NH) of up to 3x1023cm-2 from their X-ray spectra. Optical properties of X-ray absorbed AGNs with NH>1x1022cm-2 indicate the effects of dust absorption: at redshifts z<0.6, AGNs without broad H{beta} emission lines have significantly larger NH-values than AGNs with broad H{beta} emission lines. At z>0.6, the X-ray absorbed AGNs have a large hard X-ray to optical flux ratio (logf2-10keV/fR>+1). However, three X-ray absorbed z>0.6 AGNs show strong broad lines. In combination with hard X-ray-selected AGN samples from the ASCA Large Sky Survey, the ASCA Deep Survey in the Lockman Hole, and Chandra Deep Field North, the luminosity distributions of absorbed (NH>1x1022cm-2) and less-absorbed (NH<1x1022cm-2) AGNs are compared. (4 data files).

  8. AGN are cooler than you think: the intrinsic far-IR emission from QSOs

    NASA Astrophysics Data System (ADS)

    Symeonidis, M.; Giblin, B. M.; Page, M. J.; Pearson, C.; Bendo, G.; Seymour, N.; Oliver, S. J.

    2016-06-01

    We present an intrinsic AGN spectral energy distribution (SED) extending from the optical to the submm, derived with a sample of unobscured, optically luminous (νLν,5100 > 1043.5 erg s-1) QSOs at z < 0.18 from the Palomar Green survey. The intrinsic AGN SED was computed by removing the contribution from stars using the 11.3 μm polycyclic aromatic hydrocarbon (PAH) feature in the QSOs' mid-IR spectra; the 1σ uncertainty on the SED ranges between 12 and 45 per cent as a function of wavelength and is a combination of PAH flux measurement errors and the uncertainties related to the conversion between PAH luminosity and star-forming luminosity. Longwards of 20 μm, the shape of the intrinsic AGN SED is independent of the AGN power indicating that our template should be applicable to all systems hosting luminous AGN (νLν, 5100 or L_X(2-10 keV) ≳ 1043.5 erg s-1). We note that for our sample of luminous QSOs, the average AGN emission is at least as high as, and mostly higher than, the total stellar powered emission at all wavelengths from the optical to the submm. This implies that in many galaxies hosting powerful AGN, there is no `safe' broad-band photometric observation (at λ < 1000 μm) which can be used in calculating star formation rates without subtracting the AGN contribution. Roughly, the AGN contribution may be ignored only if the intrinsic AGN luminosity at 5100 AA is at least a factor of 4 smaller than the total infrared luminosity (LIR, 8-1000 μm) of the galaxy. Finally, we examine the implication of our work in statistical studies of star formation in AGN host galaxies.

  9. The Far-IR View of an Ultra-Hard X-ray Selected Sample of AGN

    NASA Astrophysics Data System (ADS)

    Shimizu, Thomas; Melendez, M.; Mushotzky, R.; Barger, A. J.; Cowie, L. L.

    2014-01-01

    We present early results of the Herschel PACS (70 and 160 μm) and SPIRE (250, 350, and 500 μm) survey of 313 low redshift (z < 0.05), ultra-hard X-ray (14-195 keV) selected AGN from the 58 month Swift/BAT catalog. Selection of AGN from ultra-hard X-rays avoids bias from obscuration that are unavoidable at other wavelengths (eg optical, infrared, and radio) providing the most complete sample of AGN to study the connection between nuclear activity and star formation in host galaxies. With the high angular resolution of PACS, we find that ~35% and ~20% of the sources are 'point-like' at 70 and 160 μm respectively with another 20% that have their flux dominated by a point source located at the nucleus. The inferred star formation rates (SFR) of 0.1 - 100 Msun yr-1 using the 70 and 160 μm flux densities and the calibration of Calzettti et al (2010) are consistent with those inferred from Spitzer NeII fluxes, but we find that 11.25 μm PAH data give ~3x lower SFR. Using GALFIT to measure the size of the FIR emitting regions, we determined the SFR density [Msun yr-1 kpc-2] for our sample, finding a significant fraction to exist above the threshold for star formation driven winds (0.1 Msun yr-1 kpc-2, Heckman 2001). Analysis of the SPIRE colors (250/350 and 350/500) also reveals evidence for the presence of nonthermal synchrotron emission from a radio jet significantly affecting the FIR emission at long wavelengths and altering the shape of the spectral energy distribution (SED). We also will present the broad band Herschel 70-500m SEDS for our sample and include archival Spitzer, WISE, FIRST and NVSS data to extend the SED down to near-IR and up to radio wavelengths. The SEDs will be fit using multiple models to attempt to determine the AGN contribution to the FIR (indirect or direct) and ultimately its effect on nuclear star formation.

  10. The Evolution of the Fractions of Quiescent and Star-forming Galaxies as a Function of Stellar Mass Since z = 3: Increasing Importance of Massive, Dusty Star-forming Galaxies in the Early Universe

    NASA Astrophysics Data System (ADS)

    Martis, Nicholas S.; Marchesini, Danilo; Brammer, Gabriel B.; Muzzin, Adam; Labbé, Ivo; Momcheva, Ivelina G.; Skelton, Rosalind E.; Stefanon, Mauro; van Dokkum, Pieter G.; Whitaker, Katherine E.

    2016-08-01

    Using the UltraVISTA DR1 and 3D-HST catalogs, we construct a stellar-mass-complete sample, unique for its combination of surveyed volume and depth, to study the evolution of the fractions of quiescent galaxies, moderately unobscured star-forming galaxies, and dusty star-forming galaxies as a function of stellar mass over the redshift interval 0.2 ≤ z ≤ 3.0. We show that the role of dusty star-forming galaxies within the overall galaxy population becomes more important with increasing stellar mass and grows rapidly with increasing redshift. Specifically, dusty star-forming galaxies dominate the galaxy population with {log}({M}{{star}}/{M}ȯ )≳ 10.3 at z ≳ 2. The ratio of dusty and non-dusty star-forming galaxies as a function of stellar mass changes little with redshift. Dusty star-forming galaxies dominate the star-forming population at {log}({M}{{star}}/{M}ȯ )≳ 10.0{--}10.5, being a factor of ˜3–5 more common, while unobscured star-forming galaxies dominate at {log}({M}{{star}}/{M}ȯ )≲ 10. At {log}({M}{{star}}/{M}ȯ )\\gt 10.5, red galaxies dominate the galaxy population at all redshift z < 3, either because they are quiescent (at late times) or dusty star-forming (in the early universe).

  11. The Evolution of the Fractions of Quiescent and Star-forming Galaxies as a Function of Stellar Mass Since z = 3: Increasing Importance of Massive, Dusty Star-forming Galaxies in the Early Universe

    NASA Astrophysics Data System (ADS)

    Martis, Nicholas S.; Marchesini, Danilo; Brammer, Gabriel B.; Muzzin, Adam; Labbé, Ivo; Momcheva, Ivelina G.; Skelton, Rosalind E.; Stefanon, Mauro; van Dokkum, Pieter G.; Whitaker, Katherine E.

    2016-08-01

    Using the UltraVISTA DR1 and 3D-HST catalogs, we construct a stellar-mass-complete sample, unique for its combination of surveyed volume and depth, to study the evolution of the fractions of quiescent galaxies, moderately unobscured star-forming galaxies, and dusty star-forming galaxies as a function of stellar mass over the redshift interval 0.2 ≤ z ≤ 3.0. We show that the role of dusty star-forming galaxies within the overall galaxy population becomes more important with increasing stellar mass and grows rapidly with increasing redshift. Specifically, dusty star-forming galaxies dominate the galaxy population with {log}({M}{{star}}/{M}ȯ )≳ 10.3 at z ≳ 2. The ratio of dusty and non-dusty star-forming galaxies as a function of stellar mass changes little with redshift. Dusty star-forming galaxies dominate the star-forming population at {log}({M}{{star}}/{M}ȯ )≳ 10.0{--}10.5, being a factor of ∼3–5 more common, while unobscured star-forming galaxies dominate at {log}({M}{{star}}/{M}ȯ )≲ 10. At {log}({M}{{star}}/{M}ȯ )\\gt 10.5, red galaxies dominate the galaxy population at all redshift z < 3, either because they are quiescent (at late times) or dusty star-forming (in the early universe).

  12. The VIMOS Public Extragalactic Redshift Survey (VIPERS). A support vector machine classification of galaxies, stars, and AGNs

    NASA Astrophysics Data System (ADS)

    Małek, K.; Solarz, A.; Pollo, A.; Fritz, A.; Garilli, B.; Scodeggio, M.; Iovino, A.; Granett, B. R.; Abbas, U.; Adami, C.; Arnouts, S.; Bel, J.; Bolzonella, M.; Bottini, D.; Branchini, E.; Cappi, A.; Coupon, J.; Cucciati, O.; Davidzon, I.; De Lucia, G.; de la Torre, S.; Franzetti, P.; Fumana, M.; Guzzo, L.; Ilbert, O.; Krywult, J.; Le Brun, V.; Le Fevre, O.; Maccagni, D.; Marulli, F.; McCracken, H. J.; Paioro, L.; Polletta, M.; Schlagenhaufer, H.; Tasca, L. A. M.; Tojeiro, R.; Vergani, D.; Zanichelli, A.; Burden, A.; Di Porto, C.; Marchetti, A.; Marinoni, C.; Mellier, Y.; Moscardini, L.; Nichol, R. C.; Peacock, J. A.; Percival, W. J.; Phleps, S.; Wolk, M.; Zamorani, G.

    2013-09-01

    Aims: The aim of this work is to develop a comprehensive method for classifying sources in large sky surveys and to apply the techniques to the VIMOS Public Extragalactic Redshift Survey (VIPERS). Using the optical (u∗,g',r',i') and near-infrared (NIR) data (z', Ks), we develop a classifier, based on broad-band photometry, for identifying stars, active galactic nuclei (AGNs), and galaxies, thereby improving the purity of the VIPERS sample. Methods: Support vector machine (SVM) supervised learning algorithms allow the automatic classification of objects into two or more classes based on a multidimensional parameter space. In this work, we tailored the SVM to classifying stars, AGNs, and galaxies and applied this classification to the VIPERS data. We trained the SVM using spectroscopically confirmed sources from the VIPERS and VVDS surveys. Results: We tested two SVM classifiers and concluded that including NIR data can significantly improve the efficiency of the classifier. The self-check of the best optical + NIR classifier has shown 97% accuracy in the classification of galaxies, 97% for stars, and 95% for AGNs in the 5-dimensional colour space. In the test of VIPERS sources with 99% redshift confidence, the classifier gives an accuracy equal to 94% for galaxies, 93% for stars, and 82% for AGNs. The method was applied to sources with low-quality spectra to verify their classification, hence increasing the security of measurements for almost 4900 objects. Conclusions: We conclude that the SVM algorithm trained on a carefully selected sample of galaxies, AGNs, and stars outperforms simple colour-colour selection methods and can be regarded as a very efficient classification method particularly suitable for modern large surveys. Based on observations collected at the European Southern Observatory, Cerro Paranal, Chile, using the Very Large Telescope under programme 182.A-0886 and partly 070.A-9007. Also based on observations obtained with MegaPrime/MegaCam, a joint

  13. Relativistic HD and MHD modelling for AGN jets

    NASA Astrophysics Data System (ADS)

    Keppens, R.; Porth, O.; Monceau-Baroux, R.; Walg, S.

    2013-12-01

    Relativistic hydro and magnetohydrodynamics (MHD) provide a continuum fluid description for plasma dynamics characterized by shock-dominated flows approaching the speed of light. Significant progress in its numerical modelling emerged in the last two decades; we highlight selected examples of modern grid-adaptive, massively parallel simulations realized by our open-source software MPI-AMRVAC (Keppens et al 2012 J. Comput. Phys. 231 718). Hydrodynamical models quantify how energy transfer from active galactic nuclei (AGN) jets to their surrounding interstellar/intergalactic medium (ISM/IGM) gets mediated through shocks and various fluid instability mechanisms (Monceau-Baroux et al 2012 Astron. Astrophys. 545 A62). With jet parameters representative for Fanaroff-Riley type-II jets with finite opening angles, we can quantify the ISM volumes affected by jet injection and distinguish the roles of mixing versus shock-heating in cocoon regions. This provides insight in energy feedback by AGN jets, usually incorporated parametrically in cosmological evolution scenarios. We discuss recent axisymmetric studies up to full 3D simulations for precessing relativistic jets, where synthetic radio maps can confront observations. While relativistic hydrodynamic models allow one to better constrain dynamical parameters like the Lorentz factor and density contrast between jets and their surroundings, the role of magnetic fields in AGN jet dynamics and propagation characteristics needs full relativistic MHD treatments. Then, we can demonstrate the collimating properties of an overal helical magnetic field backbone and study differences between poloidal versus toroidal field dominated scenarios (Keppens et al 2008 Astron. Astrophys. 486 663). Full 3D simulations allow one to consider the fate of non-axisymmetric perturbations on relativistic jet propagation from rotating magnetospheres (Porth 2013 Mon. Not. R. Astron. Soc. 429 2482). Self-stabilization mechanisms related to the detailed

  14. AGN-stimulated cooling of hot gas in elliptical galaxies

    NASA Astrophysics Data System (ADS)

    Valentini, Milena; Brighenti, Fabrizio

    2015-04-01

    We study the impact of relatively weak active galactic nucleus (AGN) feedback on the interstellar medium (ISM) of intermediate and massive elliptical galaxies. We find that the AGN activity, while globally heating the ISM, naturally stimulates some degree of hot gas cooling on scales of several kpc. This process generates the persistent presence of a cold ISM phase, with mass ranging between 104 and ≳ 5 × 107 M⊙, where the latter value is appropriate for group centred, massive galaxies. Widespread cooling occurs where the ratio of cooling to free-fall time before the activation of the AGN feedback satisfies tcool/tff ≲ 70, that is we find a less restrictive threshold than commonly quoted in the literature. This process helps explaining the body of observations of cold gas (both ionized and neutral/molecular) in Ellipticals and, perhaps, the residual star formation detected in many early-type galaxies. The amount and distribution of the off-centre cold gas vary irregularly with time. The cold ISM velocity field is irregular, initially sharing the (outflowing) turbulent hot gas motion. Typical velocity dispersions of the cold gas lie in the range 100-200 km s-1. Freshly generated cold gas often forms a cold outflow and can appear kinematically misaligned with respect to the stars. We also follow the dust evolution in the hot and cold gas. We find that the internally generated cold ISM has a very low dust content, with representative values of the dust-to-gas ratio of 10-4-10-5. Therefore, this cold gas can escape detection in the traditional dust-absorption maps.

  15. A Search for AGN Intra-Day Variability with KVN

    NASA Astrophysics Data System (ADS)

    Lee, Taeseok; Trippe, Sascha; Oh, Junghwan; Byun, Do-Young; Sohn, Bong-Won; Lee, Sang-Sung

    2015-10-01

    Active galactic nuclei (AGN) are known for irregular variability on all time scales, down to intra-day variability with relative variations of a few percent within minutes to hours. On such short timescales, unexplored territory, such as the possible existence of a shortest characteristic time scale of activity and the shape of the high frequency end of AGN power spectra, still exists. We present the results of AGN single-dish fast photometry performed with the Korean VLBI Network (KVN). Observations were done in a "anti-correlated" mode using two antennas, with always at least one antenna pointing at the target. This results in an effective time resolution of less than three minutes. We used all four KVN frequencies, 22, 43, 86, and 129 GHz, in order to trace spectral variability, if any. We were able to derive high-quality light curves for 3C 111, 3C 454.3, and BL Lacertae at 22 and 43 GHz, and for 3C 279 at 86 GHz, between May 2012 and April 2013. We performed a detailed statistical analysis in order to assess the levels of variability and the corresponding upper limits. We found upper limits on flux variability ranging from ∼1.6% to ∼7.6%. The upper limits on the derived brightness temperatures exceed the inverse Compton limit by three to six orders of magnitude. From our results, plus comparison with data obtained by the University of Michigan Radio Astronomy Observatory, we conclude that we have not detected source-intrinsic variability which would have to occur at sub-per cent levels.

  16. Liners and Low Luminosity AGN in the ROSAT Database

    NASA Technical Reports Server (NTRS)

    Elvis, Martin; West, Donald K. (Technical Monitor)

    2003-01-01

    This program has led to a series of papers being written and published in the Astrophysical Journal. Together these papers try to explain major parts of the LINER and low luminosity AGN puzzle. One paper ('Accretion Disk Instabilities, Cold Dark Matter Models, and Their Role in Quasar Evolution', Hatziminaoglou E., Siemiginowska A., & Elvis M., 2001, ApJ, 547, 90) describes an analytical model for the evolution of the quasar luminosity function. By combining the Press-Schechter formalism for the masses of initial structures with the luminosity distribution for a population of single mass black holes given by an unstable accretion disk an almost complete end-to-end physics-based model of quasar evolution is produced. In this model black holes spend 75% of their time in a low accretion state (at L(Edd)). This low state population of black holes is likely to be observed as the LINER and low luminosity AGNs in the local universe. Another paper ('Broad Emission Line Regions in AGN: the Link with the Accretion Power', Nicastro F., 2000, ApJ Letters, 530, L65) gives a physical basis for why low state black holes appear as LINERS. By linking the Lightman-Eardley instability in an accretion disk to the ori.gin of a wind that contains the broad emission line cloud material this model explains the large widths seen in these lines as being the Keplerian velocity of the disk at the instability radius. For LINERS the key is that below an accretion rate of 10(exp -3)M(sub Edd)the Lightman-Eardley instability falls within the innermost stable orbit of the disk, and so leaves the entire disk stable. No wind occurs, and so no broad emission lines are seen. Most LINERS are likely to be black holes in this low state. Tests of this model are being considered.

  17. Fossil AGN jets as ultrahigh-energy particle accelerators

    NASA Astrophysics Data System (ADS)

    Benford, Gregory; Protheroe, R. J.

    2008-01-01

    Remnants of active galactic nucleus (AGN) jets and their surrounding cocoons leave colossal magnetohydrodynamic (MHD) fossil structures storing total energies ~1060 erg. The original AGN may be dead but the fossil will retain its stable configuration resembling the reversed-field pinch (RFP) encountered in laboratory MHD experiments. In an RFP the longitudinal magnetic field changes direction at a critical distance from the axis, leading to magnetic reconnection there, and to slow decay of the large-scale RFP field. We show that this field decay induces large-scale electric fields which can accelerate cosmic rays with an E-2 power law up to ultrahigh energies with a cut-off depending on the fossil parameters. The cut-off is expected to be rigidity dependent, implying the observed composition would change from light to heavy close to the cut-off if one or two nearby AGN fossils dominate. Given that several per cent of the Universe's volume may house such slowly decaying structures, these fossils may even re-energize ultrahigh-energy cosmic rays from distant/old sources, offsetting the `GZK-losses' due to interactions with photons of the cosmic microwave background radiation and giving evidence of otherwise undetectable fossils. In this case the composition would remain light to the highest energies if distant sources or fossils dominated, but otherwise would be mixed. It is hoped the new generation of cosmic ray experiments such as the Pierre Auger Observatory and ultrahigh-energy neutrino telescopes such as ANITA and lunar Cherenkov experiments will clarify this.

  18. Revisiting Stochastic Variability of AGNs with Structure Functions

    NASA Astrophysics Data System (ADS)

    Kozłowski, Szymon

    2016-08-01

    Discrepancies between reported structure function (SF) slopes and their overall flatness as compared to the expectations from the damped random walk (DRW) model, which generally well describes the variability of active galactic nuclei (AGNs), have triggered us to study this problem in detail. We review common AGN variability observables and identify their most common problems. Equipped with this knowledge, we study ∼9000 r-band AGN light curves from Stripe 82 of the Sloan Digital Sky Survey, using SFs described by stochastic processes with the power exponential covariance matrix of the signal. We model the “subensemble” SFs in the redshift–absolute magnitude bins with the full SF equation (including the turnover and the noise part) and a single power law (SPL; in the “red noise regime” after subtracting the noise term). The distribution of full-equation SF (SPL) slopes peaks at γ =0.55+/- 0.08 (0.52 ± 0.06) and is consistent with the DRW model. There is a hint of a weak correlation of γ with the luminosity and a lack of correlation with the black hole mass. The typical decorrelation timescale in the optical is τ =0.97+/- 0.46 year. The SF amplitude at one year obtained from the SPL fitting is {{SF}}0=0.22+/- 0.06 mag and is overestimated because the SF is already at the turnover part, so the true value is {{SF}}0=0.20+/- 0.06 mag. The asymptotic variability is {{SF}}∞ =0.25+/- 0.06 mag. It is strongly anticorrelated with both the luminosity and the Eddington ratio and is correlated with the black hole mass. The reliability of these results is fortified with Monte Carlo simulations.

  19. Agnes Mary Clerke and the Rise of Astrophysics

    NASA Astrophysics Data System (ADS)

    Brück, M. T.

    2008-03-01

    Acknowledgements; Introduction; 1. Family background in County Cork; 2. Ireland and Italy; 3. London, the literary scene; 4. The History of Astronomy; 5. A circle of astronomers; 6. A visit to South Africa; 7. The System of the Stars; 8. Social life in scientific circles; 9. Homer, the Herschels and a revised History; 10. The opinion moulder; 11. Popularisation, cryogenics and evolution; 12. Problems in Astrophysics; 13. Women in astronomy in Britain in Agnes Clerke's time; 14. Revised System of the Stars; 15. Cosmogonies, cosmology and Nature's spiritual clues; 16. Last days and retrospect; 17. Epilogue; Notes; Appendix; Bibliography; Index.

  20. Hard X-ray AGN Clustering & SMBH Growth

    NASA Astrophysics Data System (ADS)

    Cappelluti, Nico

    2012-09-01

    In this review talk I present the status of the art of the studies on AGN clustering in the X-ray band and its applications in understanding the coeval growth of SMBH and Dark Matter Halos. A well defined picture has been taken up to z~2 while, at high-z, where important physical phenomena connected with SMBH formation, the knowledge is still relegated to the study of anisotropies of the unresolved CXB. I will finally present recent applications of clustering analysis to the study of clustering pattern in the unresolved CXB, and pointing out the possibility of the detection of the first BH in the University through fluctuation analysis.

  1. Dust in the torus of the AGN unified model

    NASA Astrophysics Data System (ADS)

    Mason, Rachel E.

    2015-10-01

    In these proceedings I briefly summarize our current understanding of the dusty torus of the AGN unified model: its structure, composition, and ideas about its origin and evolution. The paper is based on an invited review talk at the 7th Meeting on Cosmic Dust, which covered dust-related topics in areas from comets to debris disks and high-redshift galaxies. This is therefore intended to be an accessible, introductory overview of the torus with some emphasis on the solid-state spectral features observed.

  2. The Properties of Low-Luminosity AGN: Variability, Accretion Rate, Black Hole Mass and Color

    NASA Astrophysics Data System (ADS)

    Oleas, Juan; Podjed, Stephanie; Sarajedini, Vicki

    2016-01-01

    We present the results from a study of ~5000 Broad-Line selected AGN from the Sloan Digital Sky Survey DR7. Galaxy and AGN templates have been fit to the SDSS spectra to isolate the AGN component. The sources have absolute magnitudes in the range -23 < Mi < -18 and lie at redshifts less than z ~ 0.8. A variability analysis reveals that the anti-correlation between luminosity and variability amplitude continues to the faintest AGN in our sample (Gallastegui-Aizpun & Sarajedini 2014), though the underlying cause of the relation is still poorly understood. To address this, we further explore the connection between AGN luminosity and variability through measurement of the Hβ line width to determine black hole mass and accretion rate. We find that AGN with the highest variability amplitudes at a given luminosity appear to have lower accretion rates compared to low amplitude variables. We also investigate correlations with AGN color and accretion rate among these low-luminosity AGN.

  3. Photometric and Astrometric Characterization of the La Silla QUEST AGN Variability Survey

    NASA Astrophysics Data System (ADS)

    Coppi, Paolo S.; Cartier, R. A.; QUEST Team

    2014-01-01

    We study the photometric and astrometric properties of the La Silla QUEST AGN Variability Survey and present preliminary results. This wide-field survey is designed to collect well-sampled AGN light curves, on day to year timescales, in order to better characterize the variability properties of a large sample of AGN selected by a variety of other techniques. These properties can then be used to test and improve AGN variability selection techniques, e.g., to better prepare for the arrival of LSST. Additionally, we hope to connect these variability properties to the fundamental physical parameters of AGN such as black hole mass. To achieve this goal, we carry out nightly observations of a set of extragalactic fields with good multiwavelength coverage such as COSMOS. The survey uses the QUEST camera (with ~7.5 square degree field-of-view) operating on the 1m ESO Schmidt located in La Silla, Chile. The survey began in March 2010 and will likely continue for at least two more years. We review our progress and present sample AGN light curves from the first two years of the survey. We use the two-year data to test for possible biases in current selection variability techniques by looking at the known AGN in the COSMOS field. The larger QUEST variabiliity survey, which is now being used to find supernova, will eventually provide high-quality AGN variability data over ~15,000 square degrees of sky.

  4. Suzaku View of the Swift/BAT Active Galactic Nuclei (I): Spectral Analysis of Six AGNs and Evidence for Two Types of Obscured Population

    NASA Technical Reports Server (NTRS)

    Eguchi, Satoshi; Ueda, Yoshihiro; Terashima, Yuichi; Mushotzky, Richard F.; Tueller, Jack

    2009-01-01

    We present a systematic spectral analysis with Suzaku of six AGNs detected in the Swift/BAT hard X-ray (15-200 keV) survey, Swift J0138.6-4001, J0255.2-0011, J0350.1-5019, J0505.7-2348, J0601.9-8636, and J1628.1-5145. This is considered to be a representative sample of new AGNs without X-ray spectral information before the BAT survey. We find that the 0.5-200 keV spectra of these sources can be uniformly fit with a base model consisting of heavily absorbed (log NH >23.5/sq cm) transmitted components, scattered lights, a reflection component, and an iron-K emission line. There are two distinct groups, three "new type" AGNs (including the two sources reported by Ueda et al. 2007) with an extremely small scattered fraction (f(sub scat) < 0:5%) and strong reflection component (R = omega/2pi > or equal to 0.8 where omega is the solid angle of the reflector), and three "classical type" ones with f(sub scat > 0.5% and R < or approx. 0.8. The spectral parameters suggest that the new type has an optically thick torus for Thomson scattering (N(sub H) approx. 10(exp 25)/sq cm) with a small opening angle theta approx. 20deg viewed in a rather face-on geometry, while the classical type has a thin torus (N(sub H) approx. 10(exp 23-24)/sq cm) with theta > or approx. 30deg. We infer that a significant number of new type AGNs with an edge-on view is missing in the current all-sky hard X-ray surveys. Subject headings: galaxies: active . gamma rays: observations . X-rays: galaxies . X-rays: general

  5. The KMOS AGN Survey at High redshift (KASHz): the prevalence and drivers of ionized outflows in the host galaxies of X-ray AGN

    NASA Astrophysics Data System (ADS)

    Harrison, C. M.; Alexander, D. M.; Mullaney, J. R.; Stott, J. P.; Swinbank, A. M.; Arumugam, V.; Bauer, F. E.; Bower, R. G.; Bunker, A. J.; Sharples, R. M.

    2016-02-01

    We present the first results from the KMOS (K-band Multi-Object Spectrograph) AGN (active galactic nuclei) Survey at High redshift (KASHz), a VLT/KMOS integral-field spectroscopic (IFS) survey of z ≳ 0.6 AGN. We present galaxy-integrated spectra of 89 X-ray AGN (L2-10 keV = 1042-1045 erg s-1), for which we observed [O III] (z ≈ 1.1-1.7) or Hα emission (z ≈ 0.6-1.1). The targets have X-ray luminosities representative of the parent AGN population and we explore the emission-line luminosities as a function of X-ray luminosity. For the [O III] targets, ≈50 per cent have ionized gas velocities indicative of gas that is dominated by outflows and/or highly turbulent material (i.e. overall line widths ≳600 km s-1). The most luminous half (i.e. LX > 6 × 1043 erg s-1) have a ≳2 times higher incidence of such velocities. On the basis of our results, we find no evidence that X-ray obscured AGN are more likely to host extreme kinematics than unobscured AGN. Our KASHz sample has a distribution of gas velocities that is consistent with a luminosity-matched sample of z < 0.4 AGN. This implies little evolution in the prevalence of ionized outflows, for a fixed AGN luminosity, despite an order-of-magnitude decrease in average star formation rates over this redshift range. Furthermore, we compare our Hα targets to a redshift-matched sample of star-forming galaxies and despite a similar distribution of Hα luminosities and likely star formation rates, we find extreme ionized gas velocities are up to ≈10 times more prevalent in the AGN-host galaxies. Our results reveal a high prevalence of extreme ionized gas velocities in high-luminosity X-ray AGN and imply that the most powerful ionized outflows in high-redshift galaxies are driven by AGN activity.

  6. Optically Elusive AGN in the 3XMM Catalog and the Chandra-COSMOS field

    NASA Astrophysics Data System (ADS)

    Pons, Estelle; Watson, Mike; Elvis, Martin; Civano, Francesca M.

    2015-01-01

    'Optically elusive AGN' are powerful X-ray sources (LHX > 1042 erg/s), but are not detected as AGN in the optical. Pons and Watson (2014) showed that in XMM these AGNs are a mix of Narrow Line Seyfert 1s, True Seyfert 2's and weak Seyfert 2s. The nature of these objects, coming from the cross-match of 3XMM with the SDSS-DR9 spectroscopic catalog, has been investigated through a detailed analysis of their IR/optical and X-ray properties. The fainter Chandra-COSMOS field should be rich in optically elusive AGNs as ¾ of the AGNs there are narrow-lined. There are ~850 Chandra-COSMOS galaxy spectra, mainly from five different telescopes (SDSS, Magellan, MMT, VLT and Keck). To find optically elusive objects, we investigate the optical classification using emission line diagnostic diagrams. For low redshift galaxies (z~<0.7) the standard BPT diagram ([OIII

  7. Quantifying the impact of AGN and nebular emission on stellar population properties with REBETIKO

    NASA Astrophysics Data System (ADS)

    Cardoso, L. S. M.; Gomes, J. M.; Papaderos, P.

    2016-06-01

    Spectral synthesis enables the reconstruction of the star formation and chemical evolution histories (SFH & CEH) of a galaxy that are encoded in its spectral energy distribution (SED). Most state-of-the-art population synthesis codes however consider only purely stellar emission and are hence inadequate for modelling studies of galaxies where non-stellar emission components contribute significantly to the SED. This work combines evolutionary and population synthesis techniques to quantify the impact of active galactic nucleus (AGN) and nebular emission on the determination of the stellar population properties in galaxies. We have developed an evolutionary synthesis code called REBETIKO - Reckoning galaxy Emission By means of Evolutionary Tasks with Input Key Observables - to compute and study the time evolution of the SED of AGN-hosts and starburst galaxies. Our code takes into account the main ingredients of a galaxy's SED (e.g. non-thermal emission and/or nebular continuum and lines) for various commonly used parameterizations of the SFH, such as instantaneous burst, constant, exponentially decreasing, and gradually increasing peaking at a redshift between 1-10. Synthetic SEDs computed with REBETIKO have been subsequently fitted with the STARLIGHT population synthesis code (PSC) which can be regarded as representative for currently available state-of-the-art (i.e. purely stellar) PSCs. The objective is to study the impact of non-stellar SED components on the recovery of the true total stellar mass M_{star} and SFH of a galaxy, as well as other evolutionary properties, such as CEH and light- and mass-weighted mean stellar age and metallicity. We find that purely stellar fits in galaxies with a strong non-stellar continuum (e.g. Seyfert and/or starburst galaxies) can for instance overestimate M_{star} by up to 3 orders of magnitude, while the mean stellar age and metallicity can deviate from their true values up to 2 and 4 dex, respectively. These results imply

  8. An AGN Identification for 3EG J2006-2321

    NASA Technical Reports Server (NTRS)

    Wallace, P. M.; Halpern, J. P.; Magalhaes, A. M.; Thompson, D. J.; White, Nicholas E. (Technical Monitor)

    2001-01-01

    We present a multiwavelength analysis of the high-energy gamma-ray source 3EG J2006-2321 (l = 18 deg.82, b = -26 deg.26). The flux of this source above 100 MeV is shown to be variable on time scales of days and months. Optical observations and careful examination of archived radio data indicate that its most probable identification is with PMN J2005-2310, a flat-spectrum radio quasar with a 5GHz flux density of 260 mJy. Study of the V = 19.3 optical counterpart indicates a redshift of 0.833 and variable linear polarization. No X-ray source has been detected near the position of PMN J2005-2310, but an X-ray upper limit is derived from ROSAT data. This upper limit provides for a spectral energy distribution with global characteristics similar to those of known gamma-ray blazars. Taken together, these data indicate that 3EG J2006-2321, listed as unidentified in the 3rd EGRET Catalog, is a member of the blazar class of AGN. The 5-GHz radio flux density of this blazar is the lowest of the 68 EGRET-detected AGN. The fact that EGRET has detected such a source has implications for unidentified EGRET sources, particularly those at high latitudes (absolute value of b greater than 30 deg), many of which may be blazars.

  9. Hot Gas and AGN Feedback in Galaxies and Nearby Groups

    NASA Astrophysics Data System (ADS)

    Jones, Christine; Forman, William; Bogdan, Akos; Randall, Scott; Kraft, Ralph; Churazov, Eugene

    2013-07-01

    Massive galaxies harbor a supermassive black hole at their centers. At high redshifts, these galaxies experienced a very active quasar phase, when, as their black holes grew by accretion, they produced enormous amounts of energy. At the present epoch, these black holes still undergo occasional outbursts, although the mode of their energy release is primarily mechanical rather than radiative. The energy from these outbursts can reheat the cooling gas in the galaxy cores and maintain the red and dead nature of the early-type galaxies. These outbursts also can have dramatic effects on the galaxy-scale hot coronae found in the more massive galaxies. We describe research in three areas related to the hot gas around galaxies and their supermassive black holes. First we present examples of galaxies with AGN outbursts that have been studied in detail. Second, we show that X-ray emitting low-luminosity AGN are present in 80% of the galaxies studied. Third, we discuss the first examples of extensive hot gas and dark matter halos in optically faint galaxies.

  10. XMM-Newton, powerful AGN winds and galaxy feedback

    NASA Astrophysics Data System (ADS)

    Pounds, K.; King, A.

    2016-06-01

    The discovery that ultra-fast ionized winds - sufficiently powerful to disrupt growth of the host galaxy - are a common feature of luminous AGN is major scientific breakthrough led by XMM-Newton. An extended observation in 2014 of the prototype UFO, PG1211+143, has revealed an unusually complex outflow, with distinct and persisting velocities detected in both hard and soft X-ray spectra. While the general properties of UFOs are consistent with being launched - at the local escape velocity - from the inner disc where the accretion rate is modestly super-Eddington (King and Pounds, Ann Rev Astron Astro- phys 2015), these more complex flows have raised questions about the outflow geometry and the importance of shocks and enhanced cooling. XMM-Newton seems likely to remain the best Observatory to study UFOs prior to Athena, and further extended observations, of PG1211+143 and other bright AGN, have the exciting potential to establish the typical wind dynamics, while providing new insights on the accretion geometry and continuum source structure. An emphasis on such large, coordinated observing programmes with XMM-Newton over the next decade will continue the successful philosophy pioneered by EXOSAT, while helping to inform the optimum planning for Athena

  11. The evolution of AGN's at x ray wavelengths

    NASA Technical Reports Server (NTRS)

    Maccacaro, Tommaso; Dellaceca, R.; Gioia, I. M.; Stocke, J. T.; Wolter, A.

    1992-01-01

    The cosmological evolution and the Luminosity Function (LF) of x-ray selected Active Galactic Nuclei (AGN) are discussed. The sample used is extracted from the Einstein Observatory Extended Medium Sensitivity Survey (EMSS) and consists of more than 420 objects. Preliminary results from the Rosat all sky survey data confirm the correctness of the optical identification of the EMSS sources, thus giving confidence to the results obtained from the analysis of the AGN sample. The XLF observed at different redshifts gives direct evidence of cosmological evolution. Data were analyzed within the framework of luminosity evolution models and the two most common evolutionary forms were considered. Luminosity dependent evolution is required if the evolution function has the exponential form, whereas the simpler pure luminosity evolution model is still acceptable if the evolution function has the power law form. Using the whole sample of objects the number counts and the devolved XLF were derived. A comparison of the EMSS Data with preliminary Rosat results indicates an overall agreement.

  12. Exploring the Variability Characteristics of the Fermi AGN Sample

    NASA Astrophysics Data System (ADS)

    Shrader, Chris R.

    2016-04-01

    The Fermi Gamma-Ray Space Telescope (Fermi) has cataloged over 3000 gamma-ray (>100 MeV) point sources of which ~70% are likely AGN. The AGN are predominantly representative of the radio-loud “blazar” subclass. The emission from these objects is known to be dominated by relativistic beaming and is almost always variable, often exhibiting high-amplitude flaring. To date there have been numerous studies of individual objects including multi-wavelength campaigns with some including parsec-scale radio jet morphological studies. These studies have led to new insight in to our understanding of the blazar phenomena and jet propagation. However, there remains a dearth of statistical information on the variability characteristics of the population in aggregate. What, for example, are the distributions of flare amplitudes, durations, temporal profiles and recurrence histories among the gamma-ray blazar subclasses? We present some results of our study of a large ( ~103) set of gamma-ray light curves. For the brightest subset we explore in greater detail their properties such as morphologies and their rise and decay timescales. We include where plausible the associated energy dependencies of these rise and decay profiles. We discuss our results in terms of the possible implications on the scale and location of jet structures associated with the emission sites and the cooling timescales of the electron population producing the gamma rays.

  13. Effects of AGN feedback in galaxy groups and Intergalactic Medium

    NASA Astrophysics Data System (ADS)

    Lagos, C.; Padilla, N.; Cora, S.

    2009-05-01

    The combination of Cosmological numerical simulations and semi-analytical models of galaxy formation is a very appropriate method to study how different phenomena influence the galaxy and galaxy cluster formation. The main advantage of this combination consists in the fact that N-body simulations do not need to be rerun every time a change in the assumptions about baryonic processes is made since these are included in the semi-analytical models which run on the final N-Body simulation output. The Semi-analytic model takes into account radiative cooling of gas, stellar formation and different types of SN contribution, which eject energy and metals to the interstellar medium, allowing the chemical enrichment of the intergalactic medium. In this project we use the semi-analytic hybrid model by Cora (2006, MNRAS, 368, 1540) and implement the AGN feedback, in two modes, the QSO mode (which takes into account mergers and galactic disk instabilities), and the Radio mode, which modifies the cooling in the galaxies These two processes allow to suppress the super flows in the hybrid model, and allows the study of QSOs in galaxy groups. This new implementation opens different possibles studies including the QSO luminosity function, the anti-hierarchical evolution of Mass Function, the BH mass and bulge mass relation, Color-Magnitude diagrams, TF relation, the galaxy luminosity function, the effects of AGN in neighbor galaxies and the behavior of QSOs in the sub-millimeter window.

  14. Eclipsing the innermost accretion disc regions in AGN

    NASA Astrophysics Data System (ADS)

    Sanfrutos, M.; Miniutti, G.; Dovčiak, M.; Agís-González, B.

    2016-05-01

    Variable X-ray absorption has been observed in active galactic nuclei (AGN) on several time scales. Observations allow us to identify the absorber with clouds associated either with the clumpy torus (parsec scales, long timescales) or with the broad line region (BLR) (short timescales). In the latter, the cloud size has been estimated to be of the order of few gravitational radii from the observed absorption variability. Such small cloud sizes are comparable to the X-ray emitting regions so that a detailed modeling of occultation events in AGN has the potential of enabling us to infer accurately the geometry of the system. We have developed a relativistic X-ray spectral model for occultation events and we present here theoretical predictions on the different observables that can be inferred by studying X-ray eclipses in simulated XMM-Newton data. These include the size of the X-ray emitting regions as well as more fundamental parameters such as the black hole spin and the system inclination. We find that absorption varies as a function of the energy range and that its maximum takes place when the approaching part of the accretion disc is covered. Therefore we study the hard-to-soft (H / S) ratio light curves produced during an eclipse and use them to characterise the properties of the inner accretion disc in a new model-independent way.

  15. Studying AGN Feedback in Galaxy Clusters and Groups with Athena

    NASA Astrophysics Data System (ADS)

    Sanders, Jeremy; Athena Topical PanelAGN Feedback in Clusters; Groups

    2015-09-01

    In the centres of clusters of galaxies and groups the central active galactic nuclei are playing a vital role in preventing the rapid cooling of the surrounding hot atmosphere. Important scientific questions remain unanswered, however. These include (1) What is the mechanism by which the energy from jets is dissipated and distributed through intracluster or intragroup medium? (2) How is the AGN fuelling regulated? (3) What is the cumulative impact of powerful radio galaxies on baryons over cosmic time? With its high spectral resolution, good spatial resolution and large effective area, Athena promises to make important progress in answering these questions. For the first time it will measure both the spatially-resolved velocity distribution and thermodynamics of the cluster core region, allowing us to measure all the energetic contributions to feedback and cooling in the hot plasma. We describe how Athena will address these areas, as described in our supporting paper for the Athena mission proposal on AGN feedback in galaxy clusters and groups.

  16. AGN-Induced Cavities in NGC 1399 And NGC 4649

    SciTech Connect

    Shurkin, K.; Dunn, R.J.H.; Gentile, G.; Taylor, G.B.; Allen, S.W.; /KIPAC, Menlo Park

    2007-11-14

    We present an analysis of archival Chandra and VLA observations of the E0 galaxy NGC1399 and the E2 galaxy NGC4649 in which we investigate cavities in the surrounding X-ray emitting medium caused by the central AGN. We calculate the jet power required for the AGN to evacuate these cavities and find values of {approx} 8x10{sup 41} erg s-1 and {approx} 14x10{sup 41} erg s{sup -1} for the lobes of NGC1399 and {approx} 7x10{sup 41} erg s{sup -1} and {approx} 6x1041 erg s{sup -1} for those of NGC4649. We also calculate the k/f values for each cavity, where k is the ratio of the total particle energy to that of electrons radiating in the range of 10 MHz to 10 GHz, and f is the volume filling factor of the plasma in the cavity. We find that the values of k/f for the lobes of NGC1399 are {approx} 93 and {approx} 190, and those of the lobes of NGC4649 are {approx} 15000 and {approx} 12000. We conclude that the assumed spectrum describes the electron distribution in the lobes of NGC1399 reasonably well, and that there are few entrained particles. For NGC4649, either there are many entrained particles or the model spectrum does not accurately describe the population of electrons.

  17. Dynamics of matter available for accretion in AGN

    NASA Astrophysics Data System (ADS)

    Proga, Daniel

    We propose to study fluid dynamics in the central regions of active galaxies. Several key attributes of AGN, such as infall rates onto the central black hole and the geometry and rates of outward energy and momentum transfer, are determined in their central regions. However, despite many years of intensive studies, how radiation and mass outflows affect the structure of active galaxies remains uncertain, mostly because multi- dimensional geometrical effects and the dynamics of gas and dust are poorly understood. We will construct time-dependent, multi-dimensional radiation hydrodynamical simulations to study, from first principles, the morphology of central galactic flows on scales ranging from subparsec to tens of parsecs. The novel features of our proposed models are: (1) radiative heating and cooling of dust and gas, (2) radiation pressure on dust and gas,
(3) the essential physics of dust sublimation, and (4) radiative transfer. The results of this project will reveal the basic physical properties of flows in AGN with unprecedented accuracy and detail. We will use our models to calculate diagnostics such as line profiles, broad band spectra, and intensity maps. These diagnostics will be compared with observations by both current NASA missions such as HST, Chandra, Spitzer, and Swift and planned missions such as JWST.

  18. Multiple AGN in the crowded field of the compact group SDSS J0959+1259

    NASA Astrophysics Data System (ADS)

    De Rosa, A.; Bianchi, S.; Bogdanović, T.; Decarli, R.; Herrero-Illana, R.; Husemann, B.; Komossa, S.; Kun, E.; Loiseau, N.; Paragi, Z.; Perez-Torres, M.; Piconcelli, E.; Schawinski, K.; Vignali, C.

    2015-10-01

    We present a multiwavelength study of a newly discovered compact group (CG), SDSS J0959+1259, based data from XMM-Newton, Sloan Digital Sky Survey (SDSS) and the Calar Alto optical imager BUSCA. With a maximum velocity offset of 500 km s-1, a mean redshift of 0.035, and a mean spatial extension of 480 kpc, this CG is exceptional in having the highest concentration of nuclear activity in the local Universe, established with a sensitivity limit LX > 4 × 1040 erg s-1 in 2-10 keV band and R-band magnitude MR < -19. The group is composed of two type-2 Seyferts, one type-1 Seyfert, two LINERs and three star-forming galaxies. Given the high X-ray luminosity of LINERs which reaches ˜1041 erg s-1, it is likely that they are also accretion driven, bringing the number of active nuclei in this group to five out of eight (AGN fraction of 60 per cent). The distorted shape of one member of the CG suggests that strong interactions are taking place among its galaxies through tidal forces. Therefore, this system represents a case study for physical mechanisms that trigger nuclear activity and star formation in CGs.

  19. Radiation pressure confinement - III. The origin of the broad ionization distribution in AGN outflows

    NASA Astrophysics Data System (ADS)

    Stern, Jonathan; Behar, Ehud; Laor, Ari; Baskin, Alexei; Holczer, Tomer

    2014-12-01

    The winds of ionized gas driven by active galactic nuclei (AGN) can be studied through absorption lines in their X-ray spectra. A recurring feature of these outflows is their broad ionization distribution, including essentially all ionization levels (e.g., Fe0+ to Fe25+). This characteristic feature can be quantified with the absorption measure distribution (AMD), defined as the distribution of column density with ionization parameter |dN/d log ξ|. Observed AMDs extend over 0.1 ≲ ξ ≲ 104 (cgs), and are remarkably similar in different objects. Power-law fits (|dN/d log ξ| ≈ N1ξa) yield N1 = 3 × 1021 cm- 2 ± 0.4 dex and a = 0-0.4. What is the source of this broad ionization distribution, and what sets the small range of observed N1 and a? A common interpretation is a multiphase outflow, with a wide range of gas densities in a uniform gas pressure medium. However, the incident radiation pressure leads to a gas pressure gradient in the photoionized gas, and therefore to a broad range of ionization states within a single slab. We show that this compression of the gas by the radiation pressure leads to an AMD with |dN/d log ξ| = 8 × 1021 ξ0.03 cm-2, remarkably similar to that observed. The calculated values of N1 and a depend weakly on the gas metallicity, the ionizing spectral slope, the distance from the nucleus, the ambient density, and the total absorber column. Thus, radiation pressure compression (RPC) of the photoionized gas provides a natural explanation for the observed AMD. RPC predicts that the gas pressure increases with decreasing ionization, which can be used to test the validity of RPC in ionized AGN outflows.

  20. A search for X-ray reprocessing echoes in the power spectral density functions of AGN

    NASA Astrophysics Data System (ADS)

    Emmanoulopoulos, D.; Papadakis, I. E.; Epitropakis, A.; Pecháček, T.; Dovčiak, M.; McHardy, I. M.

    2016-09-01

    We present the results of a detailed study of the X-ray power spectral density (PSD) functions of 12 X-ray bright AGN, using almost all the archival XMM-Newton data. The total net exposure of the EPIC-pn light curves is larger than 350 ks in all cases (and exceeds 1 Ms in the case of 1H 0707-497). In a physical scenario in which X-ray reflection occurs in the inner part of the accretion disc of AGN, the X-ray reflection component should be a filtered echo of the X-ray continuum signal and should be equal to the convolution of the primary emission with the response function of the disc. Our primary objective is to search for these reflection features in the 5-7 keV (iron line) and 0.5-1 keV (soft) bands, where the X-ray reflection fraction is expected to be dominant. We fit to the observed periodograms two models: a simple bending power-law model (BPL) and a BPL model convolved with the transfer function of the accretion disc assuming the lamp-post geometry and X-ray reflection from a homogeneous disc. We do not find any significant features in the best-fitting BPL model residuals either in individual PSDs in the iron band, soft and full band (0.3-10 keV) or in the average PSD residuals of the brightest and more variable sources (with similar black hole mass estimates). The typical amplitude of the soft and full-band residuals is around 3-5 per cent. It is possible that the expected general relativistic effects are not detected because they are intrinsically lower than the uncertainty of the current PSDs, even in the strong relativistic case in which X-ray reflection occurs on a disc around a fast rotating black hole having an X-ray source very close above it. However, we could place strong constrains to the X-ray reflection geometry with the current data sets if we knew in advance the intrinsic shape of the X-ray PSDs, particularly its high-frequency slope.

  1. A search for X-ray reprocessing echoes in the power spectral density functions of AGN

    NASA Astrophysics Data System (ADS)

    Emmanoulopoulos, D.; Papadakis, I. E.; Epitropakis, A.; Pecháček, T.; Dovčiak, M.; McHardy, I. M.

    2016-06-01

    We present the results of a detailed study of the X-ray power spectra density (PSD) functions of twelve X-ray bright AGN, using almost all the archival XMM-Newton data. The total net exposure of the EPIC-pn light curves is larger than 350 ks in all cases (and exceeds 1 Ms in the case of 1H 0707-497). In a physical scenario in which X-ray reflection occurs in the inner part of the accretion disc of AGN, the X-ray reflection component should be a filtered echo of the X-ray continuum signal and should be equal to the convolution of the primary emission with the response function of the disc. Our primary objective is to search for these reflection features in the 5 - 7 keV (iron line) and 0.5 - 1 keV (soft) bands, where the X-ray reflection fraction is expected to be dominant. We fit to the observed periodograms two models: a simple bending power law model (BPL) and a BPL model convolved with the transfer function of the accretion disc assuming the lamp-post geometry and X-ray reflection from a homogeneous disc. We do not find any significant features in the best-fitting BPL model residuals either in individual PSDs in the iron band, soft and full band (0.3 - 10 keV) or in the average PSD residuals of the brightest and more variable sources (with similar black hole mass estimates). The typical amplitude of the soft and full-band residuals is around 3 - 5 per cent. It is possible that the expected general relativistic effects are not detected because they are intrinsically lower than the uncertainty of the current PSDs, even in the strong relativistic case in which X-ray reflection occurs on a disc around a fast rotating black hole having an X-ray source very close above it. However, we could place strong constrains to the X-ray reflection geometry with the current data sets if we knew in advance the intrinsic shape of the X-ray PSDs, particularly its high frequency slope.

  2. Fractional vector calculus and fractional Maxwell's equations

    SciTech Connect

    Tarasov, Vasily E.

    2008-11-15

    The theory of derivatives and integrals of non-integer order goes back to Leibniz, Liouville, Grunwald, Letnikov and Riemann. The history of fractional vector calculus (FVC) has only 10 years. The main approaches to formulate a FVC, which are used in the physics during the past few years, will be briefly described in this paper. We solve some problems of consistent formulations of FVC by using a fractional generalization of the Fundamental Theorem of Calculus. We define the differential and integral vector operations. The fractional Green's, Stokes' and Gauss's theorems are formulated. The proofs of these theorems are realized for simplest regions. A fractional generalization of exterior differential calculus of differential forms is discussed. Fractional nonlocal Maxwell's equations and the corresponding fractional wave equations are considered.

  3. PRIMUS + DEEP2: Clustering of X-Ray, Radio, and IR-AGNs at z~0.7

    NASA Astrophysics Data System (ADS)

    Mendez, Alexander J.; Coil, Alison L.; Aird, James; Skibba, Ramin A.; Diamond-Stanic, Aleksandar M.; Moustakas, John; Blanton, Michael R.; Cool, Richard J.; Eisenstein, Daniel J.; Wong, Kenneth C.; Zhu, Guangtun

    2016-04-01

    We measure the clustering of X-ray, radio, and mid-IR-selected active galactic nuclei (AGNs) at 0.2\\lt z\\lt 1.2 using multi-wavelength imaging and spectroscopic redshifts from the PRIMUS and DEEP2 redshift surveys, covering seven separate fields spanning ∼10 deg 2 . Using the cross-correlation of AGNs with dense galaxy samples, we measure the clustering scale length and slope, as well as the bias, of AGNs selected at different wavelengths. Similar to previous studies, we find that X-ray and radio AGNs are more clustered than mid-IR-selected AGNs. We further compare the clustering of each AGN sample with matched galaxy samples designed to have the same stellar mass, star-formation rate (SFR), and redshift distributions as the AGN host galaxies and find no significant differences between their clustering properties. The observed differences in the clustering of AGNs selected at different wavelengths can therefore be explained by the clustering differences of their host populations, which have different distributions in both stellar mass and SFR. Selection biases inherent in AGN selection therefore determine the clustering of observed AGN samples. We further find no significant difference between the clustering of obscured and unobscured AGNs, using IRAC or Wide-field Infrared Survey Explorer colors or X-ray hardness ratio.

  4. A Sub-Arcsecond Mid-Infrared Survey of X-Ray-Selected AGN

    NASA Astrophysics Data System (ADS)

    Levenson, N. A.; Alonso-Herrero, A.; Packham, Chris; Los Piratas AGN Science Team

    2015-08-01

    Detailed studies of local active galactic nuclei (AGN) following X-ray selection yields significant measurements of the physical properties of the AGN and their host galaxies. In turn, the complete analysis of the nearby cases at high spatial resolution---to distinguish multiple physical components---and high signal-to-noise ratio informs broader surveys of more distant examples where such observations are not possible. We apply these methods in the Los Piratas survey, which emphasizes new observations at mid-infrared wavelengths obtained using CanariCam on the 10.4m Gran Telescopio Canarias. We measure intrinsic bolometric luminosity of the roughly 100 AGN in the sample using X-rays, ensuring a span of luminosity over a range of activity level (from low-ionization nuclei through Seyfert galaxies and quasars), optical type, and radio loudness. The mid-infrared observations at resolution of ~0.3arcsec correspond to typical spatial scales of 60 pc for the low-luminosity AGN and Seyferts and 400 pc for other types. We isolate the AGN emission that is reprocessed by dust in the central regions, which we model in a clumpy distribution. We distinguish this emission from the stellar contributions on larger scales. Across types, the AGN-heated dust emission is overall well-correlated with the X-ray flux, but stellar contributions can be significant on larger scales, especially at moderate AGN luminosity.

  5. Role of the α-Glucanase Agn1p in Fission-Yeast Cell Separation

    PubMed Central

    Dekker, Nick; Speijer, Dave; Grün, Christian H.; van den Berg, Marlene; de Haan, Annett; Hochstenbach, Frans

    2004-01-01

    Cell division in the fission yeast Schizosaccharomyces pombe yields two equal-sized daughter cells. Medial fission is achieved by deposition of a primary septum flanked by two secondary septa within the dividing cell. During the final step of cell division, cell separation, the primary septum is hydrolyzed by an endo-(1,3)-β-glucanase, Eng1p. We reasoned that the cell wall material surrounding the septum, referred to here as the septum edging, also must be hydrolyzed before full separation of the daughter cells can occur. Because the septum edging contains (1,3)-α-glucan, we investigated the cellular functions of the putative (1,3)-α-glucanases Agn1p and Agn2p. Whereas agn2 deletion results in a defect in endolysis of the ascus wall, deletion of agn1 leads to clumped cells that remained attached to each other by septum-edging material. Purified Agn1p hydrolyzes (1,3)-α-glucan predominantly into pentasaccharides, indicating an endo-catalytic mode of hydrolysis. Furthermore, we show that the transcription factors Sep1p and Ace2p regulate both eng1 and agn1 expression in a cell cycle-dependent manner. We propose that Agn1p acts in concert with Eng1p to achieve efficient cell separation, thereby exposing the secondary septa as the new ends of the daughter cells. PMID:15194814

  6. The Average 0.5-200 keV Spectrum of AGNs at 0

    NASA Astrophysics Data System (ADS)

    Ballantyne, David R.

    2013-04-01

    The X-ray spectra of AGNs span nearly three decades in energy and are comprised of many separate components: a power-law with a high energy cutoff, reflection from the accretion disk as well as distant material, and, in many cases, a soft excess. Aside from a small number of bright sources observed with BeppoSAX, the full energy range of AGN spectra has only been studied in piecemeal by a fleet of X-ray observatories that can only focus on a small part of the entire spectrum. Therefore, while catalogues of the spectral properties of hundreds of AGNs have been published in different energy bands, these results are isolated from one another and a clear picture of the broadband spectral properties of typical AGNs remains elusive. In this work, we make use of the 0 X-ray luminosity functions of AGNs in the 0.5-2 keV, 2-10 keV, 3-20 keV, 15-55 keV and 14-195 keV bands to construct the spectral model of an average AGN that can simultaneously account for all 5 luminosity functions. Enhanced iron abundances, disk reflection, and the presence or absence of the X-ray Baldwin Effect are considered, along with the traditional parameters of photon index and cutoff energy. Applications to X-ray background modelling and AGN physics are discussed.

  7. Binary Black Holes, Accretion Disks and Relativistic Jets: Photocenters of Nearby AGN and Quasars

    NASA Technical Reports Server (NTRS)

    Wehrle, Ann E.; Jones, Dayton L.; Meier, David L.; Piner, B. Glenn; Unwin, Stephen C.

    2004-01-01

    One of the most challenging questions in astronomy today is to understand the origin, structure, and evolution of the central engines in the nuclei of quasars and active galaxies (AGNs). The favoured theory involves the activation of relativistic jets from the fueling of a supermassive black hole through an accretion disk. In some AGN an outer optically thick, dusty torus is seen orbiting the black hole system. This torus is probably related to an inner accretion disk - black hole system that forms the actual powerhouse of the AGN. In radio-loud AGN two oppositely-directed radio jets are ejected perpendicular to the torus/disk system. Although there is a wealth of observational data on AGN, some very basic questions have not been definitively answered. The Space Interferometry Mission (SIM) will address the following three key questions about AGN. 1) Does the most compact optical emission from an AGN come from an accretion disk or from a relativistic jet? 2) Does the separation of the radio core and optical photocenter of the quasars used for the reference frame tie, change on the timescales of their photometric variability, or is the separation stable at the level of a few microarcseconds? 3) Do the cores of galaxies harbor binary supermassive black holes remaining from galaxy mergers? It is not known whether such mergers are common, and whether binaries would persist for a significant time.

  8. On the variable nature of low luminosity AGN

    NASA Astrophysics Data System (ADS)

    Hernandez-Garcia, Lorena

    2015-09-01

    X-ray variability is very common in active galactic nuclei (AGN), but it is still unknown if these variations occur similarly in different families of AGN. The main purpose of this work is to disentangle the true structure of low ionization nuclear emission line regions (LINERs) compared to Seyfert 2s by the study of their X-ray variations. We assembled the X-ray spectral properties, as well as the X-ray variability pattern(s), which were obtained from simultaneous spectral fittings and letting different parameters to vary in the model, derived from our previous analyses (Hernández-García et al. 2013, 2014, 2015). We find that Seyfert 2s need more complex models to fit their spectra than LINERs. Among the spectral parameters, major differences are observed in the soft (0.5-2 keV) and hard (2-10 keV) X-ray luminosities, and the Eddington ratios, which are higher in Seyfert 2s. Differences are observed also in the hard column densities, temperatures, and black hole masses, although less significant. Short-term X-ray variations cannot be claimed, while long-term variability is very common in both families. An exception is found for Compton-thick sources, which do not vary, most probably because the AGN is not accesible in the 0.5--10 keV energy band. The changes are mostly related with variations in the nuclear continuum, but other patterns of variability show that variations in the absorbers (more common in Seyfert 2s) and at soft energies can be present in a few cases. Variations at UV frequencies are observed only in LINER nuclei. The X-ray variations occur similarly in LINERs and Seyfert 2s, i.e., they are related to the nuclear continuum, although they might have different accretion mechanisms, being more efficient in Seyfert 2s. Absorption variations and changing-look sources are not usually observed in LINERs. However, UV nuclear variations are common among LINERs, indicating an unobstructed view of the inner disc where the UV emission might take place. We

  9. TORUS2015: The AGN unification scheme after 30 years

    NASA Astrophysics Data System (ADS)

    Gandhi, P.; Hoenig, S. F.

    2015-09-01

    The torus paradigm has proved to be remarkably successful at unifying the observed zoo of active galaxy (AGN) classes, despite having many manifest holes. The field is still data-driven with novel observational results at multiple wavelengths emerging rapidly. We are only now beginning to map out the structure of dusty gas feeding and obscuring AGN, and to model its evolution in galaxy growth. But these have also brought out several apparently contradictory results which must hold the key to future progress. As we celebrate 30 years of the paradigm, this is the perfect time to draw together our current knowledge and reassess the state of the field. This will be an international workshop at the University of Southampton, UK, with the objective of laying out the major challenges to the field and paving future research directions. Our hope is to facilitate plenty of informal discussions between multiwavelength observers and theorists, addressing some key issues: * What is the main driver in the unification scheme? What are the roles of orientation, mass accretion rate and feedback? * What is the nature and structure of gas and dust in the torus? Do we have a self-consistent picture across multiple wavelengths? * How critical is the role of the torus as an interface between small nuclear scales and large galactic scales? Does galaxy evolution necessarily require tori? * How close are we to self-consistently simulating nuclear activity including AGN feeding and nuclear star-formation? Workshop Rationale The three themes of accretion, orientation, and evolution will be covered through invited and solicited contributions. Different to other conferences, we are building each session around some key papers that have shaped the field or those with great future potential to do so. We specifically pit competing ideas against each other to help painting a realistic picture of the state-of-the-art. Each session will end with discussion rounds delving into important future

  10. AGN Clustering in the Local Universe: An Unbiased Picture from Swift-BAT

    SciTech Connect

    Cappelluti, N.; Ajello, M.; Burlon, D.; Krumpe, M.; Miyaji, T.; Bonoli, S.; Greiner, J.; /Garching, Max Planck Inst., MPE

    2011-08-11

    We present the clustering measurement of hard X-ray selected AGN in the local Universe. We used a sample of 199 sources spectroscopically confirmed detected by Swift-BAT in its 15-55 keV all-sky survey. We measured the real space projected auto-correlation function and detected a signal significant on projected scales lower than 200 Mpc/h. We measured a correlation length of r{sub 0} = 5.56{sup +0.49}{sub -0.43} Mpc/h and a slope {gamma} = 1.64{sup -0.08}{sub -0.07}. We also measured the auto-correlation function of Tyep I and Type II AGN and found higher correlation length for Type I AGN. We have a marginal evidence of luminosity dependent clustering of AGN, as we detected a larger correlation length of luminous AGN than that of low luminosity sources. The corresponding typical host DM halo masses of Swift-BAT are {approx} log(M{sub DMH) {approx} 12-14 h{sup -1}M/M{sub {circle_dot}} which is the typical mass of a galaxy group. We estimated that the local AGN population has a typical lifetime {tau}{sub AGN} {approx}0.7 Gyr, it is powered by SMBH with mass M{sub BH} {approx}1-10x10{sup 8} M{sub {circle_dot}} and accreting with very low efficiency, log({epsilon}){approx}-2.0>. We also conclude that local AGN galaxies are typically red-massive galaxies with stellar mass of the order 2-80x10{sup 10} h{sup -1}M{sub {circle_dot}}. We compared our results with clustering predictions of merger-driven AGN triggering models and found a good agreement.

  11. Dust Obscured AGN are Masquerading as Star Formation in the Early Universe

    NASA Astrophysics Data System (ADS)

    Kirkpatrick, Allison; Pope, Alexandra; Sajina, Anna; Roebuck, Eric

    2016-01-01

    The buildup of stellar and black hole mass peaked during z=1-3, making this a key epoch for understanding how the interplay of star formation and an active galactic nucleus (AGN) drive galaxy evolution. IR luminous galaxies, which are massive and heavily dust obscured (LIR > 1011 Lsun), dominate the stellar growth during this era, and many are harboring a hidden AGN. I have quantified the contribution of AGN heating to the infrared emission of 343 IR luminous galaxies from z=0.5-2.8 using Spitzer mid-IR spectroscopy, available for every source, making this an unprecedented sample. I classify sources as star forming galaxies, AGN, or composites based on the presence of mid-IR continuum emission due to a dusty torus. My findings are: 1) Surprisingly, 60% of IR luminous galaxies show signs of some dust heating emanating from an AGN. I quantify the far-IR emission using deep Herschel imaging and find that the strength of mid-IR AGN emission is tightly correlated with the total contribution of an AGN to LIR, which has important consequences for calculating star formation rates in dusty high redshift galaxies. I demonstrate techniques to remove the contribution of AGN to LIR when mid-IR spectroscopy is available and when only limited photometry is available. 2) The composites are a separate class of galaxy which show a true mix of star formation and AGN activity in their mid- and far-IR emission. Because of dust obscuration, this activity is largely undetected at other wavelengths. This composite population is important for understanding galaxy evolution and makes up at least 30% of the deepest IR selected samples. I underscore the importance of considering composite galaxies separately in studies of star formation and black hole growth at high redshift.

  12. Unravelling ICM Physics and AGN Feedback with Deep Chandra Observations of NGC 5813

    NASA Astrophysics Data System (ADS)

    Randall, Scott; Nulsen, Paul; Jones, Christine; Forman, William; Clarke, Tracy

    2015-09-01

    We present results based on very deep (650 ks) Chandra observations of the galaxy group NGC 5813. This system shows three pairs of collinear cavities, with each pair associated with an elliptical AGN outburstshock. Due to the relatively regular morphology of this system, and the unique unambiguous detection of three distinct AGN outburstshocks, it is particularly well-suited for the study of AGN feedbackand the AGN outburst history. The implied mean kinetic power is roughly the same for each outburst, demonstrating that the average AGN kinetic luminosity can remain stable over long timescales (roughly 50Myr). The two older outbursts have larger, roughly equal total energies as compared with the youngest outburst, implying that the youngest outburst is ongoing. We find that the radiative cooling rate and the mean shock heating rate of the gas are well balanced at each shock front, suggesting that AGN outburst shock heating alone is sufficient to offset cooling and establish AGN/ICM feedback within at least the central 30 kpc. This heating takes place roughly isotropically and most strongly at small radii, as is required for feedback to operate. We suggest that shock heating may play a significant role in AGN feedback at smaller radii in other systems, where weak shocks are more difficult to detect. We find non-zero shockfront widths that are too large to be explained by particle diffusion. Instead, all measured widths are consistent with shock broadening due to propagation through a turbulent ICM with a mean turbulent speed of roughly 70 km/s. Significant contributions to our understanding of AGN feedback and ICM physics, partially via studies similar to the one described here, will be one of the major achievements of the Athena mission.

  13. The HELLAS2XMM survey. XIII. Multi-component analysis of the spectral energy distribution of obscured AGN

    NASA Astrophysics Data System (ADS)

    Pozzi, F.; Vignali, C.; Comastri, A.; Bellocchi, E.; Fritz, J.; Gruppioni, C.; Mignoli, M.; Maiolino, R.; Pozzetti, L.; Brusa, M.; Fiore, F.; Zamorani, G.

    2010-07-01

    magnitude for models with high optical depth (τ9.7 µm = 10). The ratio between the luminosities obtained by the fitting procedure and from the observed SED suggest that, at least for type 2 AGN, observed bolometric luminosities are likely to underestimate intrinsic ones and the effect is more severe for highly obscured sources. Bolometric corrections from the hard X-ray band are computed and have a median value of k2-10 keV ~ 20. The obscured AGN in our sample are characterized by relatively low Eddington ratios (median λEdd ~ 0.08). On average, they are consistent with the Eddington ratio increasing at increasing bolometric correction.

  14. Constraining AGN Feedback in Massive Ellipticals with South Pole Telescope Measurements of the Thermal Sunyaev-Zel'dovich Effect

    NASA Astrophysics Data System (ADS)

    Spacek, Alexander; Scannapieco, Evan; Cohen, Seth; Joshi, Bhavin; Mauskopf, Philip

    2016-03-01

    Energetic feedback due to active galactic nuclei (AGNs) is likely to play an important role in the observed anti-hierarchical trend in the evolution of galaxies, and yet the energy injected into the circumgalactic medium by this process is largely unknown. One promising approach to constrain this feedback is through measurements of spectral distortions in the cosmic microwave background due to the thermal Sunyaev-Zeldovich (tSZ) effect, whose magnitude is directly proportional to the energy input by AGNs. With current instruments, making such measurements requires stacking large numbers of objects to increase signal-to-noise. While one possible target for such stacks is AGNs themselves, these are relatively scarce sources that contain contaminating emission that complicates tSZ measurements. Here we adopt an alternative approach and co-add South Pole Telescope SZ (SPT-SZ) survey data around a large set of massive quiescent elliptical galaxies at z≥slant 0.5, which are much more numerous and less contaminated than active AGNs, yet are subject to the same feedback processes from the AGNs they hosted in the past. We use data from the Blanco Cosmology Survey and VISTA Hemisphere Survey to create a large catalog of galaxies split up into two redshift bins: one with 3394 galaxies at 0.5≤slant z≤slant 1.0 and one with 924 galaxies at 1.0≤slant z≤slant 1.5, with typical stellar masses of 1.5× {10}11{M}⊙ . We then co-add the emission around these galaxies, resulting in a measured tSZ signal at 2.2σ significance for the lower redshift bin and a contaminating signal at 1.1σ for the higher redshift bin. To remove contamination due to dust emission, we use SPT-SZ source counts to model a contaminant source population in both the SPT-SZ bands and Planck high-frequency bands for a subset of 937 galaxies in the low-redshift bin and 240 galaxies in the high-redshift bin. This increases our detection to 3.6σ for low redshifts and 0.9σ for high redshifts. We find the

  15. Initialized Fractional Calculus

    NASA Technical Reports Server (NTRS)

    Lorenzo, Carl F.; Hartley, Tom T.

    2000-01-01

    This paper demonstrates the need for a nonconstant initialization for the fractional calculus and establishes a basic definition set for the initialized fractional differintegral. This definition set allows the formalization of an initialized fractional calculus. Two basis calculi are considered; the Riemann-Liouville and the Grunwald fractional calculi. Two forms of initialization, terminal and side are developed.

  16. Tempered fractional calculus

    NASA Astrophysics Data System (ADS)

    Sabzikar, Farzad; Meerschaert, Mark M.; Chen, Jinghua

    2015-07-01

    Fractional derivatives and integrals are convolutions with a power law. Multiplying by an exponential factor leads to tempered fractional derivatives and integrals. Tempered fractional diffusion equations, where the usual second derivative in space is replaced by a tempered fractional derivative, govern the limits of random walk models with an exponentially tempered power law jump distribution. The limiting tempered stable probability densities exhibit semi-heavy tails, which are commonly observed in finance. Tempered power law waiting times lead to tempered fractional time derivatives, which have proven useful in geophysics. The tempered fractional derivative or integral of a Brownian motion, called a tempered fractional Brownian motion, can exhibit semi-long range dependence. The increments of this process, called tempered fractional Gaussian noise, provide a useful new stochastic model for wind speed data. A tempered fractional difference forms the basis for numerical methods to solve tempered fractional diffusion equations, and it also provides a useful new correlation model in time series.

  17. Tempered fractional calculus

    SciTech Connect

    Sabzikar, Farzad; Meerschaert, Mark M.; Chen, Jinghua

    2015-07-15

    Fractional derivatives and integrals are convolutions with a power law. Multiplying by an exponential factor leads to tempered fractional derivatives and integrals. Tempered fractional diffusion equations, where the usual second derivative in space is replaced by a tempered fractional derivative, govern the limits of random walk models with an exponentially tempered power law jump distribution. The limiting tempered stable probability densities exhibit semi-heavy tails, which are commonly observed in finance. Tempered power law waiting times lead to tempered fractional time derivatives, which have proven useful in geophysics. The tempered fractional derivative or integral of a Brownian motion, called a tempered fractional Brownian motion, can exhibit semi-long range dependence. The increments of this process, called tempered fractional Gaussian noise, provide a useful new stochastic model for wind speed data. A tempered fractional difference forms the basis for numerical methods to solve tempered fractional diffusion equations, and it also provides a useful new correlation model in time series.

  18. Revealing the Evolving Accretion Disk Corona in AGNs with Multi-Epoch X-ray Spectroscopy: the case of Mrk 335