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Sample records for agn emission lines

  1. 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 emission line equivalent widths, suggest a predominance of inclined objects in which obscuration/inclination allows us to see and study weaker emission components which are generally swamped by the direct 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.

  2. Broad emission lines variability: a window into the heart of AGN

    NASA Astrophysics Data System (ADS)

    Ilic, Dragana; Popovic, Luka C.; Shapovalova, Alla I.; Afanasiev, V. L.; Chavushyan, V. H.; Burenkov, A.; Kollatschny, W.; Kovacevic, A.

    2016-08-01

    The broad emission lines of active galactic nuclei (AGN) are known to vary both in flux and shape, and are often showing very complex line profiles. They can give us invaluable information about the kinematics and geometry of the broad line region (BLR) where these lines are originating from. The BLR is close to the supermassive black hole in AGN and may hold basic information about the formation and fueling of AGN.Here we summarize the results of the line and continuum variability of a sample of broad line AGN, obtained with the long-term optical monitoring campaign performed with telescopes of SAO (Russia), OAGH and OAN-SPM (Mexico), and Calar Alto (Spain). We monitored different type of broad line AGN (double-peaked, radio loud and radio quiet, NLSy1 and a supermassive binary black hole candidate) which show different variability characteristics that can be explained by different physical properties in BLR.

  3. X-ray Spectroscopy of the most extreme Balmer-line disk-emission AGN

    NASA Astrophysics Data System (ADS)

    Eracleous, Michael

    2005-10-01

    We propose to obtain simultaneous X-ray and UV observations of the most extreme AGN with double-peaked Balmer emission lines (FWHM > 19000km/s). We will use the XMM-Newton data to measure their X-ray spectral shapes and construct spectral energy distributions. We will combine these with measurements of the optical emission line profiles (from simultaneous HET observations) and luminosities to (a) test models for illumination of the outer disk by the central X-ray source, (b) test models for the structure of the inner accretion disk (radiatively inefficient accretion vs. standard disk), and (c) compare the X-ray-to-optical properties of these broadest Balmer-line objects to those of broad and narrow line AGN to test models for the origin of the low-ionization broad lines.

  4. Mid-IR Properties of an Unbiased AGN Sample of the Local Universe. 1; Emission-Line Diagnostics

    NASA Technical Reports Server (NTRS)

    Weaver, K. A.; Melendez, M.; Muhotzky, R. F.; Kraemer, S.; Engle, K.; Malumuth. E.; Tueller, J.; Markwardt, C.; Berghea, C. T.; Dudik, R. P.; Winter, L. M.; Armus, L.

    2010-01-01

    \\Ve compare mid-IR emission-lines properties, from high-resolution Spitzer IRS spectra of a statistically-complete hard X-ray (14-195 keV) selected sample of nearby (z < 0.05) AGN detected by the Burst Alert Telescope (BAT) aboard Swift. The luminosity distribution for the mid-infrared emission-lines, [O IV] 25.89 microns, [Ne II] 12.81 microns, [Ne III] 15.56 microns and [Ne V] 14.32 microns, and hard X-ray continuum show no differences between Seyfert 1 and Seyfert 2 populations, although six newly discovered BAT AGNs are shown to be under-luminous in [O IV], most likely the result of dust extinction in the host galaxy. The overall tightness of the mid-infrared correlations and BAT luminosities suggests that the emission lines primarily arise in gas ionized by the AGN. We also compared the mid-IR emission-lines in the BAT AGNs with those from published studies of star-forming galaxies and LINERs. We found that the BAT AGN fall into a distinctive region when comparing the [Ne III]/[Ne II] and the [O IV]/[Ne III] quantities. From this we found that sources that have been previously classified in the mid-infrared/optical as AGN have smaller emission line ratios than those found for the BAT AGNs, suggesting that, in our X-ray selected sample, the AGN represents the main contribution to the observed line emission. Overall, we present a different set of emission line diagnostics to distinguish between AGN and star forming galaxies that can be used as a tool to find new AGN.

  5. Emission-Line Taxonomy and the Nature of AGN-Looking Galaxies in the SDSS

    NASA Astrophysics Data System (ADS)

    Cid Fernandes, Roberto; Stasińska, Grażyna; Vale Asari, Natalia; Mateus, Abílio; Schlickmann, Marielli S.; Schoenell, William; Schoenell

    2010-05-01

    Massive spectroscopic surveys like the SDSS have revolutionized the way we study AGN and their relations to the galaxies they live in. A first step in any such study is to define samples of different types of AGN on the basis of emission-line ratios. This deceivingly simple step involves decisions on which classification scheme to use and data quality censorship. Galaxies with weak emission lines are often left aside or dealt with separetely because one cannot fully classify them onto the standard star-forming, Seyfert, or LINER categories. This contribution summarizes alternative classification schemes which include this very numerous population. We then study how star-formation histories and physical properties of the hosts vary from class to class, and present compelling evidence that the emission lines in the majority of LINER-like systems in the SDSS are not powered by black-hole accretion. The data are fully consistent with them being galaxies whose old stars provide all the ionizing power needed to explain their line ratios and luminosities. Such retired galaxies deserve a place in the emission-line taxonomy.

  6. THE CONNECTIONS BETWEEN THE UV AND OPTICAL Fe ii EMISSION LINES IN TYPE 1 AGNs

    SciTech Connect

    Kovacević-Dojcinović, Jelena; Popović, Luka Č. E-mail: lpopovic@aob.bg.ac.rs

    2015-12-15

    We investigate the spectral properties of the UV (λλ2650–3050 Å) and optical (λλ4000–5500 Å) Fe ii emission features in a sample of 293 Type 1 active galactic nuclei (AGNs) from the Sloan Digital Sky Survey database. We explore different correlations between their emission line properties, as well as the correlations with other emission lines from the spectral range. We find several interesting correlations and outline the most interesting results as follows. (i) There is a kinematical connection between the UV and optical Fe ii lines, indicating that the UV and optical Fe ii lines originate from the outer part of the broad line region, the so-called intermediate line region. (ii) The unexplained anticorrelations of the optical Fe ii equivalent width (EW Fe ii{sub opt}) versus EW [O iii] 5007 Å and EW Fe ii{sub opt} versus FWHM Hβ have not been detected for the UV Fe ii lines. (iii) The significant averaged redshift in the UV Fe ii lines, which is not present in optical Fe ii, indicates an inflow in the UV Fe ii emitting clouds, and probably their asymmetric distribution. (iv) Also, we confirm the anticorrelation between the intensity ratio of the optical and UV Fe ii lines and the FWHM of Hβ, and we find the anticorrelations of this ratio with the widths of Mg ii 2800 Å, optical Fe ii, and UV Fe ii. This indicates a very important role for the column density and microturbulence in the emitting gas. We discuss the starburst activity in high-density regions of young AGNs as a possible explanation of the detected optical Fe ii correlations and intensity line ratios of the UV and optical Fe ii lines.

  7. The Connections Between the UV and Optical Fe ii Emission Lines in Type 1 AGNs

    NASA Astrophysics Data System (ADS)

    Kovačević-Dojčinović, Jelena; Popović, Luka Č.

    2015-12-01

    We investigate the spectral properties of the UV (λλ2650-3050 Å) and optical (λλ4000-5500 Å) Fe ii emission features in a sample of 293 Type 1 active galactic nuclei (AGNs) from the Sloan Digital Sky Survey database. We explore different correlations between their emission line properties, as well as the correlations with other emission lines from the spectral range. We find several interesting correlations and outline the most interesting results as follows. (i) There is a kinematical connection between the UV and optical Fe ii lines, indicating that the UV and optical Fe ii lines originate from the outer part of the broad line region, the so-called intermediate line region. (ii) The unexplained anticorrelations of the optical Fe ii equivalent width (EW Fe iiopt) versus EW [O iii] 5007 Å and EW Fe iiopt versus FWHM Hβ have not been detected for the UV Fe ii lines. (iii) The significant averaged redshift in the UV Fe ii lines, which is not present in optical Fe ii, indicates an inflow in the UV Fe ii emitting clouds, and probably their asymmetric distribution. (iv) Also, we confirm the anticorrelation between the intensity ratio of the optical and UV Fe ii lines and the FWHM of Hβ, and we find the anticorrelations of this ratio with the widths of Mg ii 2800 Å, optical Fe ii, and UV Fe ii. This indicates a very important role for the column density and microturbulence in the emitting gas. We discuss the starburst activity in high-density regions of young AGNs as a possible explanation of the detected optical Fe ii correlations and intensity line ratios of the UV and optical Fe ii lines.

  8. THE LICK AGN MONITORING PROJECT 2011: SPECTROSCOPIC CAMPAIGN AND EMISSION-LINE LIGHT CURVES

    SciTech Connect

    Barth, Aaron J.; Bennert, Vardha N.; Canalizo, Gabriela; Filippenko, Alexei V.; Li, Weidong; Gates, Elinor L.; Greene, Jenny E.; Malkan, Matthew A.; Treu, Tommaso; Pancoast, Anna; Sand, David J.; Stern, Daniel; Woo, Jong-Hak; Assef, Roberto J.; Bae, Hyun-Jin; Brewer, Brendon J.; Cenko, S. Bradley; and others

    2015-04-15

    In the Spring of 2011 we carried out a 2.5 month reverberation mapping campaign using the 3 m Shane telescope at Lick Observatory, monitoring 15 low-redshift Seyfert 1 galaxies. This paper describes the observations, reductions and measurements, and data products from the spectroscopic campaign. The reduced spectra were fitted with a multicomponent model in order to isolate the contributions of various continuum and emission-line components. We present light curves of broad emission lines and the active galactic nucleus (AGN) continuum, and measurements of the broad Hβ line widths in mean and rms spectra. For the most highly variable AGNs we also measured broad Hβ line widths and velocity centroids from the nightly spectra. In four AGNs exhibiting the highest variability amplitudes, we detect anticorrelations between broad Hβ width and luminosity, demonstrating that the broad-line region “breathes” on short timescales of days to weeks in response to continuum variations. We also find that broad Hβ velocity centroids can undergo substantial changes in response to continuum variations; in NGC 4593, the broad Hβ velocity shifted by ∼250 km s{sup −1} over a 1 month period. This reverberation-induced velocity shift effect is likely to contribute a significant source of confusion noise to binary black hole searches that use multi-epoch quasar spectroscopy to detect binary orbital motion. We also present results from simulations that examine biases that can occur in measurement of broad-line widths from rms spectra due to the contributions of continuum variations and photon-counting noise.

  9. The Lick AGN Monitoring Project 2011: Spectroscopic Campaign and Emission-line Light Curves

    NASA Technical Reports Server (NTRS)

    Barth, Aaron J.; Bennert, Vardha N.; Canalizo, Gabriela; Filippenko, Alexei V.; Gates, Elinor L.; Greene, Jenny E..; Li, Weidong; Malkan, Matthew A.; Pancoast, Anna; Sand, David J.; Stern, Daniel; Cenko, S. Bradley

    2016-01-01

    In the Spring of 2011 we carried out a 2.5 month reverberation mapping campaign using the 3 m Shane telescope at Lick Observatory, monitoring 15 low-redshift Seyfert 1 galaxies. This paper describes the observations, reductions and measurements, and data products from the spectroscopic campaign. The reduced spectra were fitted with a multicomponent model in order to isolate the contributions of various continuum and emission-line components. We present light curves of broad emission lines and the active galactic nucleus (AGN) continuum, and measurements of the broad Hß line widths in mean and rms spectra. For the most highly variable AGNs we also measured broad H beta line widths and velocity centroids from the nightly spectra. In four AGNs exhibiting the highest variability amplitudes, we detect anticorrelations between broad H beta width and luminosity, demonstrating that the broad-line region "breathes" on short timescales of days to weeks in response to continuum variations. We also find that broad H beta velocity centroids can undergo substantial changes in response to continuum variations; in NGC 4593, the broad H beta velocity shifted by approximately 250 km s(exp -1) over a 1 month period. This reverberation-induced velocity shift effect is likely to contribute a significant source of confusion noise to binary black hole searches that use multi-epoch quasar spectroscopy to detect binary orbital motion. We also present results from simulations that examine biases that can occur in measurement of broad-line widths from rms spectra due to the contributions of continuum variations and photon-counting noise.

  10. The Lick AGN Monitoring Project 2011: Spectroscopic Campaign and Emission-line Light Curves

    NASA Astrophysics Data System (ADS)

    Barth, Aaron J.; Bennert, Vardha N.; Canalizo, Gabriela; Filippenko, Alexei V.; Gates, Elinor L.; Greene, Jenny E.; Li, Weidong; Malkan, Matthew A.; Pancoast, Anna; Sand, David J.; Stern, Daniel; Treu, Tommaso; Woo, Jong-Hak; Assef, Roberto J.; Bae, Hyun-Jin; Brewer, Brendon J.; Cenko, S. Bradley; Clubb, Kelsey I.; Cooper, Michael C.; Diamond-Stanic, Aleksandar M.; Hiner, Kyle D.; Hönig, Sebastian F.; Hsiao, Eric; Kandrashoff, Michael T.; Lazarova, Mariana S.; Nierenberg, A. M.; Rex, Jacob; Silverman, Jeffrey M.; Tollerud, Erik J.; Walsh, Jonelle L.

    2015-04-01

    In the Spring of 2011 we carried out a 2.5 month reverberation mapping campaign using the 3 m Shane telescope at Lick Observatory, monitoring 15 low-redshift Seyfert 1 galaxies. This paper describes the observations, reductions and measurements, and data products from the spectroscopic campaign. The reduced spectra were fitted with a multicomponent model in order to isolate the contributions of various continuum and emission-line components. We present light curves of broad emission lines and the active galactic nucleus (AGN) continuum, and measurements of the broad Hβ line widths in mean and rms spectra. For the most highly variable AGNs we also measured broad Hβ line widths and velocity centroids from the nightly spectra. In four AGNs exhibiting the highest variability amplitudes, we detect anticorrelations between broad Hβ width and luminosity, demonstrating that the broad-line region “breathes” on short timescales of days to weeks in response to continuum variations. We also find that broad Hβ velocity centroids can undergo substantial changes in response to continuum variations; in NGC 4593, the broad Hβ velocity shifted by ˜250 km s-1 over a 1 month period. This reverberation-induced velocity shift effect is likely to contribute a significant source of confusion noise to binary black hole searches that use multi-epoch quasar spectroscopy to detect binary orbital motion. We also present results from simulations that examine biases that can occur in measurement of broad-line widths from rms spectra due to the contributions of continuum variations and photon-counting noise.

  11. BAT AGN spectroscopic survey-II. X-ray emission and high-ionization optical emission lines

    NASA Astrophysics Data System (ADS)

    Berney, Simon; Koss, Michael; Trakhtenbrot, Benny; Ricci, Claudio; Lamperti, Isabella; Schawinski, Kevin; Baloković, Mislav; Crenshaw, D. Michael; Fischer, Travis; Gehrels, Neil; Harrison, Fiona; Hashimoto, Yasuhiro; Ichikawa, Kohei; Mushotzky, Richard; Oh, Kyuseok; Stern, Daniel; Treister, Ezequiel; Ueda, Yoshihiro; Veilleux, Sylvain; Winter, Lisa

    2015-12-01

    We investigate the relationship between X-ray and optical line emission in 340 nearby (z ≃ 0.04) AGN selected above 10 keV using Swift BAT. We find a weak correlation between the extinction corrected [O III] and hard X-ray luminosity (L_[O III]^{int} ∝ L_{14-195}) with a large scatter (RPear = 0.64, σ = 0.62 dex) and a similarly large scatter with the intrinsic 2-10 keV to [O III] luminosities (RPear = 0.63, σ = 0.63 dex). Correlations of the hard X-ray fluxes with the fluxes of high-ionization narrow lines ([O III], He II, [Ne III] and [Ne V]) are not significantly better than with the low-ionization lines (H α, [S II]). Factors like obscuration or physical slit size are not found to be a significant part of the large scatter. In contrast, the optical emission lines show much better correlations with each other (σ = 0.3 dex) than with the X-ray flux. The inherent large scatter questions the common usage of narrow emission lines as AGN bolometric luminosity indicators and suggests that other issues such as geometrical differences in the scattering of the ionized gas or long-term AGN variability are important.

  12. HST Ultraviolet Spectrum of ARP 102B, the Prototypical Double-Peaked Emission-Line AGN

    NASA Astrophysics Data System (ADS)

    Eracleous, M.; Filippenko, A. V.; Halpern, J. P.; Chen, K.

    1995-12-01

    UV spectra of the nucleus of the elliptical galaxy Arp 102B were obtained with the HST's Faint Object Spectrograph in order to investigate the UV emission-line counterparts of its unusual double-peaked Balmer lines. Broad Mg II lambda 2798 is present with nearly the same profile as the Balmer lines (peaks separated by ~ 12,000 km s(-1) ), and a typical Mg II/Hβ ratio of 1. But there is little, if any C III] lambda 1909 or C IV lambda 1550 emission corresponding to the displaced Balmer-line peaks. Most important, there is no double-peaked component detected in Lyalpha ; the Lyalpha /Hβ ratio is < 0.12 in the displaced peaks. However, there is an ``ordinary,'' non-displaced broad-line component with FWHM ~ 3500 km s(-1) in all of the permitted lines, demonstrating the need to invoke different locations and different physical conditions for double-peaked and single-peaked line components in the same object. The striking absence of displaced peaks in Lyalpha cannot be explained solely by reddening. Rather, it indicates that high density and large optical depth in Lyalpha are required to destroy the line photons by collisional deexcitation and possibly by bound-free absorption out of the n=2 level of hydrogen. These results strongly support the application, at least to Arp 102B, of the accretion-disk model of Dumont and Collin-Souffrin, in which the disk produces only low-ionization lines and a Lyalpha /Hβ ratio that agrees with our upper limit. Also present is an extraordinary system of absorption lines at the systemic redshift of Arp 102B, in which metastable levels of Fe II up to 1.1 eV above the ground state participate in addition to the more common resonance transitions. Absorption from metastable levels has been seen previously only in two unusual, low-ionization BALQSOs, Q0059--2735 and Mrk 231. Why they are seen in absorption in Arp 102B, a relatively unobscured AGN, but in no other appropriately observed Seyfert or radio galaxy, is a mystery.

  13. Looking for the broad emission lines in AGN2 with deep NIR spectroscopy and the measure of the mass of Intermediate Mass BH

    NASA Astrophysics Data System (ADS)

    Onori, Francesca; La Franca, Fabio; Ricci, Federica

    According to the current models of galaxy evolution, in a hierarchical cosmology low mass Black Holes (10 (4) - 10 (7) M_⊙) at low redshift contain clues about the formation of the first Black Holes and Galaxies. Moreover, as they extend the dynamic range of the BH-mass/galaxy scaling relations to extreme values, they could be very useful in constraining the AGN/Galaxy co-evolutionary models. In the past years, in the framework of the verification of the AGN unified model, there have been several attempts to detect faint broad emission lines in type 2 AGN with both NIR and polarised spectroscopy. We here present the new results from a systematic study, performed using deep NIR (VLT and LBT) spectroscopy, of about 50 AGN2, drawn from the complete SWIFT/BAT 22-month had X-ray selected sample. A new virial relation able to measure the BH mass using the broad component of the Paschenbeta line will be also presented. Thanks to the above relation we have been able to directly measure, when the BLR has been detected, the BH mass of type 2 AGNs, finding that AGN2 show on average lower masses than the AGN1 population. The implications to the AGN unified model and AGN/galaxy co-evolution scenarios will be discussed.

  14. Using the H-β Emission Line as a Means of Mass Determination for Spiral Galaxy AGNs

    NASA Astrophysics Data System (ADS)

    Cameron, Thomas; Ratz, Lucus; Burris, Debra L.

    2016-01-01

    This study focuses on the AGN of spiral galaxies in hopes to use the H-β line to determine the mass of the central black hole. We are replicating the method of Vestergaard and Peterson by extinction correcting emission spectra from these black holes, both for cosmic redshift and for FeII emissions using IRAF. From there we can accurately measure the full width half max of the H-beta line in these spectrum as well as the lumosity and these paired with the OIII lines give us an estimate on the mass of the black hole. The purpose of this is to compare it to the values to pitch angle measurements and to explore the Mass-Pitch Angle relation as outlined by J. Kennefick from the University of Arkansas.

  15. Detection of faint broad emission lines in type 2 AGN: I. Near infrared observations and spectral fitting

    NASA Astrophysics Data System (ADS)

    Onori, F.; La Franca, F.; Ricci, F.; Brusa, M.; Sani, E.; Maiolino, R.; Bianchi, S.; Bongiorno, A.; Fiore, F.; Marconi, A.; Vignali, C.

    2016-09-01

    We present medium resolution near infrared spectroscopic observations of 41 obscured and intermediate class AGN (type 2, 1.9 and 1.8; AGN2) with redshift z ≲0.1, selected from the Swift/BAT 70-month catalogue. The observations have been carried out in the framework of a systematic study of the AGN2 near infrared spectral properties and have been executed using ISAAC/VLT, X-shooter/VLT and LUCI/LBT, reaching an average S/N ratio of ˜30 per resolution element. For those objects observed with X-shooter we also obtained simultaneous optical and UV spectroscopy. We have identified a component from the broad line region in 13 out of 41 AGN2, with FWHM >800 km s-1. We have verified that the detection of the broad line region components does not significantly depend on selection effects due to the quality of the spectra, the X-ray or near infrared fluxes, the orientation angle of the host galaxy or the hydrogen column density measured in the X-ray band. The average broad line region components found in AGN2 has a significantly (a factor 2) smaller FWHM if compared with a control sample of type 1 AGN.

  16. Molecular line emission in NGC 1068 imaged with ALMA. I. An AGN-driven outflow in the dense molecular gas

    NASA Astrophysics Data System (ADS)

    García-Burillo, S.; Combes, F.; Usero, A.; Aalto, S.; Krips, M.; Viti, S.; Alonso-Herrero, A.; Hunt, L. K.; Schinnerer, E.; Baker, A. J.; Boone, F.; Casasola, V.; Colina, L.; Costagliola, F.; Eckart, A.; Fuente, A.; Henkel, C.; Labiano, A.; Martín, S.; Márquez, I.; Muller, S.; Planesas, P.; Ramos Almeida, C.; Spaans, M.; Tacconi, L. J.; van der Werf, P. P.

    2014-07-01

    Aims: We investigate the fueling and the feedback of star formation and nuclear activity in NGC 1068, a nearby (D = 14 Mpc) Seyfert 2 barred galaxy, by analyzing the distribution and kinematics of the molecular gas in the disk. We aim to understand if and how gas accretion can self-regulate. Methods: We have used the Atacama Large Millimeter Array (ALMA) to map the emission of a set of dense molecular gas (n(H2) ≃ 105 - 6 cm-3) tracers (CO(3-2), CO(6-5), HCN(4-3), HCO+(4-3), and CS(7-6)) and their underlying continuum emission in the central r ~ 2 kpc of NGC 1068 with spatial resolutions ~0.3″ - 0.5″ (~20-35 pc for the assumed distance of D = 14 Mpc). Results: The sensitivity and spatial resolution of ALMA give an unprecedented detailed view of the distribution and kinematics of the dense molecular gas (n(H2) ≥ 105 - 6cm-3) in NGC 1068. Molecular line and dust continuum emissions are detected from a r ~ 200 pc off-centered circumnuclear disk (CND), from the 2.6 kpc-diameter bar region, and from the r ~ 1.3 kpc starburst (SB) ring. Most of the emission in HCO+, HCN, and CS stems from the CND. Molecular line ratios show dramatic order-of-magnitude changes inside the CND that are correlated with the UV/X-ray illumination by the active galactic nucleus (AGN), betraying ongoing feedback. We used the dust continuum fluxes measured by ALMA together with NIR/MIR data to constrain the properties of the putative torus using CLUMPY models and found a torus radius of 20+6-10pc. The Fourier decomposition of the gas velocity field indicates that rotation is perturbed by an inward radial flow in the SB ring and the bar region. However, the gas kinematics from r ~ 50 pc out to r ~ 400 pc reveal a massive (Mmol~ 2.7+0.9-1.2 × 107 M⊙) outflow in all molecular tracers. The tight correlation between the ionized gas outflow, the radio jet, and the occurrence of outward motions in the disk suggests that the outflow is AGN driven. Conclusions: The molecular outflow is likely

  17. A Direct Linkage between AGN Outflows in the Narrow-line Regions and the X-Ray Emission from the Accretion Disks

    NASA Astrophysics Data System (ADS)

    Wang, J.; Xu, D. W.; Wei, J. Y.

    2016-03-01

    The origin of outflow in the narrow-line region (NLR) of the active galactic nucleus (AGN) is studied in this paper by focusing on the relationship between the [O iii]λ5007 line profile and the hard-X-ray (in a bandpass of 2-10 keV) emission from the central super-massive black hole (SMBH) in type-I AGNs. A sample of 47 local X-ray selected type-I AGNs at z\\lt 0.2 is extracted from the 2XMMi/SDSS-DR7 catalog, which was originally cross-matched by Pineau et al. The X-ray luminosities in an energy band from 2 to 10 keV of these luminous AGNs range from 1042 to {10}44 {erg} {{{s}}}-1. A joint spectral analysis is performed on their optical and X-ray spectra, in which the [O iii] line profile is modeled by a sum of several Gaussian functions to quantify its deviation from a pure Gaussian function. The statistics allow us to identify a moderate correlation with a significance level of 2.78σ: luminous AGNs with stronger [O iii] blue asymmetry tend to have steeper hard-X-ray spectra. By identifying the role of L/{L}{Edd} on the correlation at a 2-3σ significance level in both direct and indirect ways, we argue that the photon index versus the asymmetry correlation provides evidence that the AGN’s outflow commonly observed in its NLR is related to the accretion process occurring around the central SMBH, which favors the wind/radiation model as the origin of the outflow in luminous AGNs.

  18. 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.

  19. The Dust Sublimation Radius as an Outer Envelope to the Bulk of the Narrow Fe Kalpha Line Emission in Type 1 AGNs

    NASA Astrophysics Data System (ADS)

    Gandhi, Poshak; Hönig, Sebastian F.; Kishimoto, Makoto

    2015-10-01

    The Fe Kα emission line is the most ubiquitous feature in the X-ray spectra of active galactic nuclei (AGNs), but the origin of its narrow core remains uncertain. Here, we investigate the connection between the sizes of the Fe Kα core emission regions and the measured sizes of the dusty tori in 13 local Type 1 AGNs. The observed Fe Kα emission radii (RFe) are determined from spectrally resolved line widths in X-ray grating spectra, and the dust sublimation radii (Rdust) are measured either from optical/near-infrared (NIR) reverberation time lags or from resolved NIR interferometric data. This direct comparison shows, on an object-by-object basis, that the dust sublimation radius forms an outer envelope to the bulk of the Fe Kα emission. RFe matches Rdust well in the AGNs, with the best constrained line widths currently. In a significant fraction of objects without a clear narrow line core, RFe is similar to, or smaller than, the radius of the optical broad line region. These facts place important constraints on the torus geometries for our sample. Extended tori in which the solid angle of fluorescing gas peaks at well beyond the dust sublimation radius can be ruled out. We also test for luminosity scalings of RFe, finding that the Eddington ratio is not a prime driver in determining the line location in our sample. We also discuss in detail potential caveats of data analysis and instrumental limitations, simplistic line modeling, uncertain black hole masses, and sample selection, showing that none of these is likely to bias our core result. The calorimeter on board Astro-H will soon vastly increase the parameter space over which line measurements can be made, overcoming many of these limitations.

  20. THE DUST SUBLIMATION RADIUS AS AN OUTER ENVELOPE TO THE BULK OF THE NARROW Fe Kα LINE EMISSION IN TYPE 1 AGNs

    SciTech Connect

    Gandhi, Poshak; Hönig, Sebastian F.; Kishimoto, Makoto

    2015-10-20

    The Fe Kα emission line is the most ubiquitous feature in the X-ray spectra of active galactic nuclei (AGNs), but the origin of its narrow core remains uncertain. Here, we investigate the connection between the sizes of the Fe Kα core emission regions and the measured sizes of the dusty tori in 13 local Type 1 AGNs. The observed Fe Kα emission radii (R{sub Fe}) are determined from spectrally resolved line widths in X-ray grating spectra, and the dust sublimation radii (R{sub dust}) are measured either from optical/near-infrared (NIR) reverberation time lags or from resolved NIR interferometric data. This direct comparison shows, on an object-by-object basis, that the dust sublimation radius forms an outer envelope to the bulk of the Fe Kα emission. R{sub Fe} matches R{sub dust} well in the AGNs, with the best constrained line widths currently. In a significant fraction of objects without a clear narrow line core, R{sub Fe} is similar to, or smaller than, the radius of the optical broad line region. These facts place important constraints on the torus geometries for our sample. Extended tori in which the solid angle of fluorescing gas peaks at well beyond the dust sublimation radius can be ruled out. We also test for luminosity scalings of R{sub Fe}, finding that the Eddington ratio is not a prime driver in determining the line location in our sample. We also discuss in detail potential caveats of data analysis and instrumental limitations, simplistic line modeling, uncertain black hole masses, and sample selection, showing that none of these is likely to bias our core result. The calorimeter on board Astro-H will soon vastly increase the parameter space over which line measurements can be made, overcoming many of these limitations.

  1. Predicted Fe II Spectra plus UV through sub-mm Emission Line Fluxes for Other Species Arising in Narrow Line Regions of AGNs

    NASA Astrophysics Data System (ADS)

    Verner, Ekaterina; Bruhweiler, F. C.; Wills, B. J.

    2009-01-01

    Optical and UV spectra indicate pronounced Fe II emission from multitudinous lines superposed on the underlying UV and optical continua of Seyferts and QSOs. Although the intrinsic UV of the these objects exhibit strong Fe II emission arising in higher density Broad Line Region (BLR) gas, observations at visual wavelengths indicate Fe II originating in both BLR and lower density Narrow Line Region (NLR) gas. Our modeling of observed intrinsic UV Fe II emission produces better fits with both BLR and NLR components. We have calculated a grid of photoionization models appropriate for NLR, spanning a range of number density [log (n/cm-3) = 1.0 to 8.0], photoionizing flux [log (Φ/cm-2 s-1) = 10.0-18.0], microturbulence (ξ = 0, 2, 10, and 20 km s-1), and abundance (0.1, 0.5, 1.0 and 5 times solar). These models include the effects of cooling from Fe II. The effects of Fe II cooling and the use of a 371 versus an 830-level atom for Fe II in producing the Fe II emission spectra are explored. We present predicted Fe II spectra from the UV through the IR, plus fluxes of important lines of other species from the UV through the sub-mm wavelength range. These predictions, besides being relevant for studies of Fe II in AGNs, provide predicted fluxes for important lines for upcoming missions such as Herschel and SOPHIA. These results will be made available to researchers via the World Wide Web. We acknowledge the support of the National Science Foundation through grant AST-0607465 to CUA.

  2. ALMA DETECTION OF THE VIBRATIONALLY EXCITED HCN J = 4-3 EMISSION LINE IN THE AGN-HOSTING LUMINOUS INFRARED GALAXY IRAS 20551–4250

    SciTech Connect

    Imanishi, Masatoshi; Nakanishi, Kouichiro

    2013-10-01

    We present results from our ALMA Cycle 0 observations, at the frequencies around the HCN, HCO{sup +}, and HNC J = 4-3 transition lines, of the luminous infrared galaxy IRAS 20551–4250 at z = 0.043, which is known to host an energetically important obscured active galactic nucleus (AGN). In addition to the targeted HCN, HCO{sup +}, and HNC J = 4-3 emission lines, two additional strong emission lines are seen, which we attribute to H{sub 2}S and CH{sub 3}CN(+CCH). The HCN-to-HCO{sup +} J = 4-3 flux ratio (∼0.7) is higher than in the other starburst-dominated galaxy (∼0.2) observed in our ALMA Cycle 0 program. We tentatively (∼5σ) detected the vibrationally excited (v {sub 2} = 1) HCN J = 4-3 (l = 1f) emission line, which is important for testing an infrared radiative pumping scenario for HCN. This is the second detection of this molecular transition in external galaxies. The most likely reason for this detection is not only the high flux of this emission line, but also the small molecular line widths observed in this galaxy, suggesting that vibrational excitation of HCN may be relatively common in AGN-hosting galaxies.

  3. A Deep X-Ray View of the Bare AGN Ark 120. I. Revealing the Soft X-Ray Line Emission

    NASA Astrophysics Data System (ADS)

    Reeves, J. N.; Porquet, D.; Braito, V.; Nardini, E.; Lobban, A.; Turner, T. J.

    2016-09-01

    The Seyfert 1 galaxy Ark 120 is a prototype example of the so-called class of bare nucleus active galactic nuclei (AGNs), whereby there is no known evidence for the presence of ionized gas along the direct line of sight. Here deep (>400 ks exposure), high-resolution X-ray spectroscopy of Ark 120 is presented from XMM-Newton observations that were carried out in 2014 March, together with simultaneous Chandra/High Energy Transmission Grating exposures. The high-resolution spectra confirmed the lack of intrinsic absorbing gas associated with Ark 120, with the only X-ray absorption present originating from the interstellar medium (ISM) of our own Galaxy, with a possible slight enhancement of the oxygen abundance required with respect to the expected ISM values in the solar neighborhood. However, the presence of several soft X-ray emission lines are revealed for the first time in the XMM-Newton RGS spectrum, associated with the AGN and arising from the He- and H-like ions of N, O, Ne, and Mg. The He-like line profiles of N, O, and Ne appear velocity broadened, with typical FWHMs of ˜5000 km s-1, whereas the H-like profiles are unresolved. From the clean measurement of the He-like triplets, we deduce that the broad lines arise from a gas of density n e ˜ 1011 cm-3, while the photoionization calculations infer that the emitting gas covers at least 10% of 4π steradian. Thus the broad soft X-ray profiles appear coincident with an X-ray component of the optical-UV broad-line region on sub-parsec scales, whereas the narrow profiles originate on larger parsec scales, perhaps coincident with the AGN narrow-line region. The observations show that Ark 120 is not intrinsically bare and substantial X-ray-emitting gas exists out of our direct line of sight toward this AGN.

  4. A Deep X-Ray View of the Bare AGN Ark 120. I. Revealing the Soft X-Ray Line Emission

    NASA Astrophysics Data System (ADS)

    Reeves, J. N.; Porquet, D.; Braito, V.; Nardini, E.; Lobban, A.; Turner, T. J.

    2016-09-01

    The Seyfert 1 galaxy Ark 120 is a prototype example of the so-called class of bare nucleus active galactic nuclei (AGNs), whereby there is no known evidence for the presence of ionized gas along the direct line of sight. Here deep (>400 ks exposure), high-resolution X-ray spectroscopy of Ark 120 is presented from XMM-Newton observations that were carried out in 2014 March, together with simultaneous Chandra/High Energy Transmission Grating exposures. The high-resolution spectra confirmed the lack of intrinsic absorbing gas associated with Ark 120, with the only X-ray absorption present originating from the interstellar medium (ISM) of our own Galaxy, with a possible slight enhancement of the oxygen abundance required with respect to the expected ISM values in the solar neighborhood. However, the presence of several soft X-ray emission lines are revealed for the first time in the XMM-Newton RGS spectrum, associated with the AGN and arising from the He- and H-like ions of N, O, Ne, and Mg. The He-like line profiles of N, O, and Ne appear velocity broadened, with typical FWHMs of ∼5000 km s‑1, whereas the H-like profiles are unresolved. From the clean measurement of the He-like triplets, we deduce that the broad lines arise from a gas of density n e ∼ 1011 cm‑3, while the photoionization calculations infer that the emitting gas covers at least 10% of 4π steradian. Thus the broad soft X-ray profiles appear coincident with an X-ray component of the optical–UV broad-line region on sub-parsec scales, whereas the narrow profiles originate on larger parsec scales, perhaps coincident with the AGN narrow-line region. The observations show that Ark 120 is not intrinsically bare and substantial X-ray-emitting gas exists out of our direct line of sight toward this AGN.

  5. Database of emission lines

    NASA Astrophysics Data System (ADS)

    Binette, L.; Ortiz, P.; Joguet, B.; Rola, C.

    1998-11-01

    A widely accessible data bank (available through Netscape) and consiting of all (or most) of the emission lines reported in the litterature is being built. It will comprise objects as diverse as HII regions, PN, AGN, HHO. One of its use will be to define/refine existing diagnostic emission line diagrams.

  6. ALMA Investigation of Vibrationally Excited HCN/HCO+/HNC Emission Lines in the AGN-Hosting Ultraluminous Infrared Galaxy IRAS 20551-4250

    NASA Astrophysics Data System (ADS)

    Imanishi, Masatoshi; Nakanishi, Kouichiro; Izumi, Takuma

    2016-07-01

    We present the results of ALMA Cycle 2 observations of the ultraluminous infrared galaxy IRAS 20551-4250 at HCN/HCO+/HNC J = 3-2 lines at both vibrational ground (v = 0) and vibrationally excited (v 2 = 1) levels. This galaxy contains a luminous buried active galactic nucleus (AGN), in addition to starburst activity, and our ALMA Cycle 0 data revealed a tentatively detected vibrationally excited HCN v 2 = 1f J = 4-3 emission line. In our ALMA Cycle 2 data, the HCN/HCO+/HNC J = 3-2 emission lines at v = 0 are clearly detected. The HCN and HNC v 2 = 1f J = 3-2 emission lines are also detected, but the HCO+ v 2 = 1f J = 3-2 emission line is not. Given the high energy level of v 2 = 1 and the resulting difficulty of collisional excitation, we compared these results with those of the calculation of infrared radiative pumping, using the available infrared 5-35 μm spectrum. We found that all of the observational results were reproduced if the HCN abundance was significantly higher than that of HCO+ and HNC. The flux ratio and excitation temperature between v 2 = 1f and v = 0, after correction for possible line opacity, suggests that infrared radiative pumping affects rotational (J-level) excitation at v = 0 at least for HCN and HNC. The HCN-to-HCO+ v = 0 flux ratio is higher than those of starburst-dominated regions, and will increase even more when the derived high HCN opacity is corrected. The enhanced HCN-to-HCO+ flux ratio in this AGN-hosting galaxy can be explained by the high HCN-to-HCO+ abundance ratio and sufficient HCN excitation at up to J = 4, rather than the significantly higher efficiency of infrared radiative pumping for HCN than HCO+.

  7. Mid-Infrared [NeII] and [NeIII] Emission Line Profiles in Starbursts and AGN

    NASA Astrophysics Data System (ADS)

    Samsonyan, A. L.

    2016-09-01

    Line profiles and velocities of the [CII] 157μm line observed with the Herschel PACS instrument are compared to high resolution [NeII] 12.81μm and [NeIII] 15.55μm emission lines observed with the Spitzer Infrared Spectrograph (IRS). We are analysing spectra of at least 400 galaxies having both IRS high resolution and Herschel PACS [CII] line profiles that are available from the public archives. The goal of the work is the comparison of emission line velocity profiles and fluxes to locate and understand differences in the origins of [CII] compared to the mid-infrared Neon lines. Line velocities and widths are carefully measured, and errors are analyzed to determine if there is any kinematic evidence for [CII] arising from clouds not visible in the mid-infrared emission lines. This will give an answer to two questions: 1. Is there evidence that [CII] is more diffuse, distributed throughout galaxies, than the mid infrared starburst indicators [NeII] and [NeIII]?; 2. Is there evidence for specific, very dusty clouds of [CII] with so much extinction that the [CII] can be seen but the [NeII] and [NeIII] is not seen?

  8. Revisiting correlations between broad-line and jet emission variations for AGNs: 3C 120 and 3C 273

    NASA Astrophysics Data System (ADS)

    Liu, H. T.; Bai, J. M.; Feng, H. C.; Li, S. K.

    2015-06-01

    We restudy the issue of cross-correlations between broad-line and jet emission variations, and aim to locate the position of a radio (and gamma-ray) emitting region in a jet of active galactic nuclei. Considering the radial profiles of the radius and number density of clouds in a spherical broad-line region (BLR), we derive new formulae connecting the jet-emitting position Rjet to the time lag τob between broad-line and jet emission variations, and the BLR radius. Also, formulae are derived for a disc-like BLR and a spherical shell BLR. The model-independent flux randomization/random subset selection method is used to estimate τob. For 3C 120, positive lags of about 0.3 yr are found between the 15 GHz emission and the Hβ, Hγ and He II λ4686 lines, including broad-line data in a newly published paper, indicating that the line variations lead the 15 GHz ones. Each of the broad-line light curves corresponds to a radio outburst. Rjet = 1.1-1.5 parsec (pc) is obtained for 3C 120. For 3C 273, a common feature of negative time lags is found in the cross-correlation functions between light curves of radio emission and the Balmer lines, as well as Lyα λ1216 and C IV λ1549 lines. Rjet = 1.0-2.6 pc is obtained for 3C 273. The estimated Rjet is comparable for 3C 120 and 3C 273, and the gamma-ray-emitting positions will be within ˜1-3 pc from the central engines. Comparisons show that the cloud number density and radius radial distributions and the BLR structures have only negligible effects on Rjet.

  9. Hubble Space Telescope Ultraviolet Spectrum of ARP 102B, the Prototypical Double-peaked Emission-Line AGN

    NASA Astrophysics Data System (ADS)

    Halpern, Jules P.; Eracleous, Michael; Filippenko, Alexei V.; Chen, Kaiyou

    1996-06-01

    UV spectra of the nucleus of the elliptical galaxy Arp 102B were obtained with the HST's Faint Object Spectrograph in order to investigate the UV emission-line counterparts of its unusual double-peaked Balmer lines. Broad Mg II λ2798 is present with nearly the same profile as the Balmer lines (peaks separated by ~12,000 km s^-1^), and a typical Mg II/Hβ ratio of 1. But there is little, if any C III] λ 1909 or C IV λ1550 emission corresponding to the displaced Balmer- line peaks. Most important, there is no double-peaked component detected in Lyα; the Lyα/Hβ ratio is less than 0.12 in the displaced peaks. However, there is an "ordinary," non-displaced broad-line component with FWHM ~3500 km s^-1^ in all of the permitted lines, demonstrating the need to invoke different locations and different physical conditions for double-peaked and single-peaked line components in the same object. The. striking absence of displaced peaks In Lyα probably cannot be explained solely by reddening. Rather, It indicates that high density and large optical depth in Lyα are required to destroy the line photons by collisional de-excitation and possibly by bound-free absorption out of the n = 2 level of hydrogen. These results strongly support the application, at least to Arp 102B, of the accretion- disk model of Dumont & Collin-Souffrin, in which the disk produces only low-ionization lines and a Lyα/Hβ ratio that agrees with our observed upper limit. Also present is an extraordinary system of absorption lines at the systemic redshift of Arp 102B, in which metastable levels of Fe II up to 1.1 eV above the ground state participate in addition to the more common resonance transitions. Absorption from metastable levels of Fe II have been seen previously only in two unusual, low-ionization broad absorption-line QSOs, Q0059 - 2735 and Mrk 231. Temperatures and densities needed to excite these levels are similar to narrow-line region conditions. Why they are seen in absorption in Arp

  10. 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.

  11. 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.

  12. THE ORIGIN OF DOUBLE-PEAKED NARROW LINES IN ACTIVE GALACTIC NUCLEI. I. VERY LARGE ARRAY DETECTIONS OF DUAL AGNs AND AGN OUTFLOWS

    SciTech Connect

    Müller-Sánchez, F.; Comerford, J. M.; Nevin, R.; Barrows, R. S.; Cooper, M. C.; Greene, J. E.

    2015-11-10

    We have examined a subset of 18 active galactic nuclei (AGNs) drawn from a sample of 81 galaxies that possess double-peaked narrow optical emission line spectra in the Sloan Digital Sky Survey, have 2 optical AGN emission components separated by >0.″2, and are detected in the Faint Images of the Radio Sky at Twenty-centimeters survey. Without follow-up observations, the sources of the double-peaked narrow emission lines are uncertain, and may be produced by kiloparsec-scale separation dual active supermassive black holes, AGN outflows, or disk rotation. In this work, we propose a new methodology to characterize double-peaked narrow emission line galaxies based on optical long-slit spectroscopy and high-resolution multi-band Very Large Array observations. The nature of the radio emission in the sample galaxies is varied. Of the 18 galaxies, we detect 2 compact flat-spectrum radio cores with projected spatial separations on the sky between 0.6 and 1.6 kpc in 3 galaxies: J1023+3243, J1158+3231, and J1623+0808. The two radio sources are spatially coincident with the two optical components of ionized gas with AGN-like line ratios, which confirms the presence of dual AGNs in these three galaxies. Dual AGNs account for only ∼15% (3/18) of the double-peaked AGNs in our sample. Gas kinematics produce ∼75% (13/18) of the double-peaked narrow emission lines, distributed in the following way: seven AGN wind-driven outflows, five radio-jet driven outflows, and one rotating narrow-line region. The remaining 10% (2/18) are ambiguous cases. Our method demonstrates the power of spatially resolved spectroscopy and high-resolution radio observations for the identification of AGN outflows and AGN pairs with angular separations as small as 0.″18.

  13. Line Shape Variability in a Sample of AGN with Broad Lines

    NASA Astrophysics Data System (ADS)

    Ilić, D.; Popović, L. Č.; Shapovalova, A. I.; Burenkov, A. N.; Chavushyan, V. H.; Kovačević, A.

    2015-12-01

    The spectral variability of active galactic nuclei (AGN) is one of the key features that enables us to study in more detail, the structure of AGN emitting regions. Especially, the broad line profiles that vary both in flux and shape, give us invaluable information about the kinematics and geometry of the broad line region (BLR) where these lines are originating from. We give here a comparative review of the line shape variability in a sample of five type 1 AGNs, those with broad emission lines in their spectra, of the data obtained from the international long-term optical monitoring campaign coordinated by the Special Astrophysical Observatory of the Russian Academy of Science. The main aim of this campaign is to study the physics and kinematics of the BLR on a uniform data set, focusing on the problems of the photoionization heating of the BLR and its geometry, where, in this paper, we give for a first time, a comparative analysis of the variabilty of five type 1 AGNs, discussing their complex BLR physics and geometry in the framework of the estimates of the supermassive black hole mass in AGN.

  14. 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.

  15. Dissecting galaxies: spatial and spectral separation of emission excited by star formation and AGN activity

    NASA Astrophysics Data System (ADS)

    Davies, Rebecca L.; Groves, Brent; Kewley, Lisa J.; Dopita, Michael A.; Hampton, Elise J.; Shastri, Prajval; Scharwächter, Julia; Sutherland, Ralph; Kharb, Preeti; Bhatt, Harish; Jin, Chichuan; Banfield, Julie; Zaw, Ingyin; James, Bethan; Juneau, Stéphanie; Srivastava, Shweta

    2016-10-01

    The optical spectra of Seyfert galaxies are often dominated by emission lines excited by both star formation and active galactic nucleus (AGN) activity. Standard calibrations (such as for the star formation rate) are not applicable to such composite (mixed) spectra. In this paper, we describe how integral field data can be used to spectrally and spatially separate emission associated with star formation from emission associated with accretion on to an AGN. We demonstrate our method using integral field data for two AGN host galaxies (NGC 5728 and NGC 7679) from the Siding Spring Southern Seyfert Spectroscopic Snapshot Survey (S7). The spectra of NGC 5728 and NGC 7679 form clear sequences of AGN fraction on standard emission line ratio diagnostic diagrams. We show that the emission line luminosities of the majority (>85 per cent) of spectra along each AGN fraction sequence can be reproduced by linear superpositions of the emission line luminosities of one AGN dominated spectrum and one star formation dominated spectrum. We separate the Hα, Hβ, [N II]λ6583, [S II]λλ6716, 6731, [O III]λ5007 and [O II]λλ3726, 3729 luminosities of every spaxel into contributions from star formation and AGN activity. The decomposed emission line images are used to derive the star formation rates and AGN bolometric luminosities for NGC 5728 and NGC 7679. Our calculated values are mostly consistent with independent estimates from data at other wavelengths. The recovered star-forming and AGN components also have distinct spatial distributions which trace structures seen in high-resolution imaging of the galaxies, providing independent confirmation that our decomposition has been successful.

  16. 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.

  17. UNDERSTANDING THE AGN-HOST CONNECTION IN BROAD Mg II EMISSION-SELECTED AGN-HOST HYBRID QUASARS

    SciTech Connect

    Wang, J.; Wei, J. Y.

    2009-05-01

    We study the issue of active galactic nucleus (AGN)-host connection in intermediate-z (1.2>z > 0.4) galaxies with hybrid spectra (hybrid QSOs for short). The observed spectra redward of the Balmer limit are dominated by starlight, and the spectra at the blue end by both an AGN continuum and an Mg II broad emission line. This unique property allows us to examine both an AGN and its host galaxy in an individual galaxy simultaneously. First, 15 hybrid QSOs are selected from the Sloan Digital Sky Survey (SDSS) Data Release 6. The spectra are then analyzed in detail for three objects: SDSS J162446.49+461946.7, SDSS J102633.32+103443.8, and SDSS J090036.44+381353.0. Our spectral analysis shows that the current star formation activities are strongly suppressed, and that the latest burst ages range from {approx}400 Myr to 1 Gyr. Based on the Mg II black hole masses, the three hybrid QSOs are consistent with the D{sub n} (4000) - L/L {sub Edd} sequence that was previously established in local AGNs. The three hybrid QSOs are located in the middle range of the sequence, which implies that the hybrid QSOs are at the transition stage not only from young to old AGNs, but also from a host-dominated phase to an AGN-dominated phase.

  18. 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.

  19. The Broad Line Region in AGNs: Structure, Physics, and the f Factor

    NASA Astrophysics Data System (ADS)

    Grier, Catherine; Peterson, B. M.; Martini, P.; Pogge, R. W.; Pancoast, A.; Treu, T.; Watson, L. C.

    2014-01-01

    We present recent results in an effort to investigate the structure of the broad line region in active galactic nuclei (AGNs) using reverberation mapping data. AGNs provide our only means for exploring the black hole (BH) population outside the local universe. To measure black hole masses (MBH) in AGNs, we use the broad line region (BLR) by assuming that the motion of the emitting gas is dominated by the gravity of the BH. Virial MBH measurements can be made using the resulting Doppler-broadened emission lines: MBH = fRΔV^2/G. R is the distance of the emitting gas from the BH, ΔV is the velocity dispersion of the emitting gas, obtained from the width of the emission line, and f is a dimensionless factor that accounts for the geometry and orientation of the BLR. Because the BLR is unresolvable, the true value of f in for each object is unknown. Typically, an average virial factor f is used, calculated by assuming that AGNs follow the same MBH--σ relation as quiescent galaxies. Our inability to directly observe the structure of the BLR and is a major source of uncertainties in MBH measurements. To learn about BLR structure, we must rely on either reverberation mapping techniques or microlensing of gravitationally lensed quasars. We have been working on various aspects of this problem using high-quality reverberation-mapping data from various observing campaigns based at MDM Observatory on Kitt Peak. Results from these reverberation efforts have a broad impact on our understanding of AGN physics as well as on all MBH measurements in AGNs that provide a basis for galaxy evolution and AGN feedback models.

  20. 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

  1. Narrow-line region gas kinematics of 24 264 optically selected AGN: the radio connection

    NASA Astrophysics Data System (ADS)

    Mullaney, J. R.; Alexander, D. M.; Fine, S.; Goulding, A. D.; Harrison, C. M.; Hickox, R. C.

    2013-07-01

    Using a sample of 24 264 optically selected active galactic nuclei (AGNs) from the SDSS DR7 data base, we characterize how the profile of the [O III] λ5007 emission line relates to bolometric luminosity (LAGN), Eddington ratio, radio loudness, radio luminosity (L1.4 GHz) and optical class (i.e. broad/narrow-line Seyfert 1, type 2) to determine what drives the kinematics of this kpc-scale line emitting gas. First, we use spectral stacking to characterize how the average [O III] λ5007 profile changes as a function of these five variables. After accounting for the known correlation between LAGN and L1.4 GHz, we report that L1.4 GHz has the strongest influence on the [O III] λ5007 profile, with AGNs of moderate radio luminosity (L1.4 GHz = 1023-1025 W Hz-1) having the broadest [O III] λ5007 profiles. Conversely, we find only a modest change in the [O III] λ5007 profile with increasing radio loudness and find no significant difference between the [O III] λ5007 profiles of broad- and narrow-line Seyfert 1s. When binned according to Eddington ratio, only the AGNs in our highest bin (i.e. >0.3) show any signs of having broadened [O III] λ5007 profiles, although the small numbers of such extreme AGNs in our sample mean we cannot rule out that other processes (e.g. radio jets) are responsible for this broadening. The [O III] λ5007 profiles of type 1 and type 2 AGNs show the same trends in terms of line width, but type 1 AGNs display a much stronger `blue wing', which we interpret as evidence of outflowing ionized gas. We perform multicomponent fitting to the Hβ, [O III] λλ4959, 5007, [N II] λλ6548, 6584 and Hα lines for all the AGNs in our sample to calculate the proportions of AGNs with broad [O III] λ5007 profiles. The individual fits confirm the results from our stacked spectra; AGNs with L1.4 GHz > 1023 W Hz-1 are roughly five times more likely to have extremely broad [O III] λ5007 lines (full width at half-maximum, FWHMAvg > 1000 km s-1) compared to

  2. The Redshift Dependence of Gamma-Ray Absorption in the Environments of Strong-Line AGNs

    SciTech Connect

    Reimer, A.; /Stanford U., HEPL /KIPAC, Menlo Park

    2007-11-12

    The case of {gamma}-ray absorption due to photon-photon pair production of jet photons in the external photon environments, such as the accretion disk and the broad-line region radiation fields, of {gamma}-ray--loud active galactic nuclei (AGNs) that exhibit strong emission lines is considered. I demonstrate that this 'local opacity,' if detected, will almost unavoidably be redshift-dependent in the sub-TeV range. This introduces nonnegligible biases and complicates approaches for studying the evolution of the extragalactic background light with contemporary GeV instruments such as the Gamma-Ray Large Area Space Telescope (GLAST ), where the {gamma}-ray horizon is probed by means of statistical analysis of absorption features (e.g., the Fazio-Stecker relation) in AGN spectra at various redshifts. It particularly applies to strong-line quasars, where external photon fields are potentially involved in {gamma}-ray production.

  3. EVOLUTION OF [O III] {lambda}5007 EMISSION-LINE PROFILES IN NARROW EMISSION-LINE GALAXIES

    SciTech Connect

    Wang, J.; Mao, Y. F.; Wei, J. Y.

    2011-11-01

    The active galactic nucleus (AGN)-host co-evolution issue is investigated here by focusing on the evolution of the [O III] {lambda}5007 emission-line profile. A large sample of narrow emission-line galaxies is selected from the Max-Planck Institute for Astrophysics/Johns Hopkins University Sloan Digital Sky Survey DR7 catalog to simultaneously measure both the [O III] line profile and circumnuclear stellar population in an individual spectrum. By requiring that (1) the [O III] line signal-to-noise ratio is larger than 30 and (2) the [O III] line width is larger than the instrumental resolution by a factor of two, our sample is narrowed down to 2333 Seyfert galaxies/LINERs (AGNs), 793 transition galaxies, and 190 star-forming galaxies. In addition to the commonly used profile parameters (i.e., line centroid, relative velocity shift, and velocity dispersion), two dimensionless shape parameters, skewness and kurtosis, are used to quantify the line shape deviation from a pure Gaussian function. We show that the transition galaxies are systematically associated with narrower line widths and weaker [O III] broad wings than the AGNs, which implies that the kinematics of emission-line gas are different in the two kinds of objects. By combining the measured host properties and line shape parameters, we find that the AGNs with stronger blue asymmetries tend to be associated with younger stellar populations. However, a similar trend is not identified in the transition galaxies. The failure likely results from a selection effect in which the transition galaxies are systematically associated with younger stellar populations than the AGNs. The evolutionary significance revealed here suggests that both narrow-line region kinematics and outflow feedback in AGNs co-evolve with their host galaxies.

  4. 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

  5. Nebular emission from AGN in the ultraviolet/optical: diagnostics of the ionizing source and gas properties

    NASA Astrophysics Data System (ADS)

    Feltre, A.

    2016-08-01

    Spectroscopic studies of active galactic nuclei (AGN) are powerful means of probing the physical properties of the ionized gas within them. In particular, forthcoming facilities such as JWST and the E-ELT, will provide rest-frame ultraviolet and optical spectra of the very distant AGN. To lay the groundwork for the interpretation of these revolutionary datasets, we have recently computed new photoionization models of the narrow-line emitting regions (NLR) of AGN and combined them with similar models of the nebular emission from star-forming galaxies. In this talk, I will first describe how new ultraviolet and standard optical spectral diagnostics allow one to distinguish between nuclear activity and star formation. I will then explain how predictions of AGN nebular emission can be best used to understand the physical properties of the AGN NLR gas. In particular, I will present recent results from a study on one of the most comprehensive set of optical spectra (from VIMOS/VLT) sampling the rest-frame ultraviolet range of ~90 type 2 AGN (1.5 < z < 3), drawn from the z-COSMOS deep survey. To conclude, I will show how the implementation of AGN photoionization calculations in an innovative Bayesian fitting code can help us best interpret current, and future, spectro-photometric data on active galaxies.

  6. Constraints on Black Hole Spin in a Sample of Broad Iron Line AGN

    NASA Technical Reports Server (NTRS)

    Brenneman, Laura W.; Reynolds, Christopher S.

    2008-01-01

    We present a uniform X-ray spectral analysis of nine type-1 active galactic nuclei (AGN) that have been previously found to harbor relativistically broadened iron emission lines. We show that the need for relativistic effects in the spectrum is robust even when one includes continuum "reflection" from the accretion disk. We then proceed to model these relativistic effects in order to constrain the spin of the supermassive black holes in these AGN. Our principal assumption, supported by recent simulations of geometrically-thin accretion disks, is that no iron line emission (or any associated Xray reflection features) can originate from the disk within the innermost stable circular orbit. Under this assumption, which tends to lead to constraints in the form of lower limits on the spin parameter, we obtain non-trivial spin constraints on five AGN. The spin parameters of these sources range from moderate (a approximates 0.6) to high (a > 0.96). Our results allow, for the first time, an observational constraint on the spin distribution function of local supermassive black holes. Parameterizing this as a power-law in dimensionless spin parameter (f(a) varies as absolute value of (a) exp zeta), we present the probability distribution for zeta implied by our results. Our results suggest 90% and 95% confidence limits of zeta > -0.09 and zeta > -0.3 respectively.

  7. Multi-epoch Spectroscopy of Dwarf Galaxies with AGN Signatures: Identifying Sources with Persistent Broad Hα Emission

    NASA Astrophysics Data System (ADS)

    Baldassare, Vivienne F.; Reines, Amy E.; Gallo, Elena; Greene, Jenny E.; Graur, Or; Geha, Marla; Hainline, Kevin; Carroll, Christopher M.; Hickox, Ryan C.

    2016-09-01

    We use time-domain optical spectroscopy to distinguish between broad emission lines powered by accreting black holes (BHs) and stellar processes (i.e., supernovae) for 16 galaxies identified as active galactic nucleus (AGN) candidates by Reines et al (2013). Our study is primarily focused on those objects with narrow emission line ratios dominated by star formation, for which the origin of the broad Hα emission was unclear. Based on follow-up spectroscopy, we find that the broad Hα emission has faded or was ambiguous for all of the star-forming objects (14/16), over baselines ranging from 5-14 years, suggesting a transient stellar process was responsible for the broad emission in previous Sloan Digital Sky Survey observations. For the two objects in our follow-up sample with narrow-line AGN signatures (RGG 9 and RGG 119), we find persistent broad Hα emission consistent with an AGN origin. Additionally, we use high spectral resolution observations to measure stellar velocity dispersions for 15 objects in the Reines et al. (2013) sample, all with narrow-line ratios indicating the presence of an AGN. Stellar masses range from ˜ 5× {10}8 to 3× {10}9 M ⊙, and we measure {σ }* in the range of 28{--}71 {km} {{{s}}}-1. These {σ }* correspond to some of the lowest-mass galaxies with optical signatures of AGN activity. We show that RGG 119, the one object that has both a measured {σ }* and persistent broad Hα emission, falls near the extrapolation of the {\\text{}}{M}{BH}-{σ }\\star relation to the low-mass end.

  8. Two Active States of the Narrow-Line Gamma-Ray-Loud AGN GB 1310 + 487

    NASA Technical Reports Server (NTRS)

    Sokolovsky, K. V.; Schinzel, F. K.; Tanaka, Y. T.; Abolmasov, P. K.; Angelakis, E.; Bulgarelli, A.; Carrasco, L.; Cenko, S. B.; Cheung, C. C.; Clubb, K. I.; D'Ammando, F.; Escande, L.; Fegan, S. J.; Filippenko, A. V.; Finke, J. D.; Fuhrmann, L.; Fukazawa, Y.; Hays, E.; Healey, S. E.; Ikejiri, Y.; Itoh, R.; Kawabata, K. S.; Komatsu, T.; Kovalev, Yu. A.; Kovalev, Y. Y.; Krichbaum, T. P.

    2014-01-01

    Context. Previously unremarkable, the extragalactic radio source GB1310 487 showed gamma-ray flare on 2009 November 18, reaching a daily flux of approximately 10(exp -6) photons cm(exp -2) s(exp -1) at energies E greater than 100MeV and became one of the brightest GeV sources for about two weeks. Its optical spectrum shows strong forbidden-line emission while lacking broad permitted lines, which is not typical for a blazar. Instead, the spectrum resembles those of narrow emission-line galaxies. Aims. We investigate changes in the object's radio-to-GeV spectral energy distribution (SED) during and after the prominent gamma-ray flare with the aim of determining the nature of the object and of constraining the origin of the variable high-energy emission. Methods. The data collected by the Fermi and AGILE satellites at gamma-ray energies; Swift at X-ray and ultraviolet (UV); the Kanata, NOT, and Keck telescopes at optical; OAGH and WISE at infrared (IR); and IRAM30m, OVRO 40m, Effelsberg 100m, RATAN-600, and VLBA at radio are analyzed together to trace the SED evolution on timescales of months. Results. The gamma-ray radio-loud narrow-line active galactic nucleus (AGN) is located at redshift z = 0.638. It shines through an unrelated foreground galaxy at z = 0.500. The AGN light is probably amplified by gravitational lensing. The AGN SED shows a two-humped structure typical of blazars and gamma-ray-loud narrow-line Seyfert 1 galaxies, with the high-energy (inverse-Compton) emission dominating by more than an order of magnitude over the low-energy (synchrotron) emission during gamma-ray flares. The difference between the two SED humps is smaller during the low-activity state. Fermi observations reveal a strong correlation between the gamma-ray flux and spectral index, with the hardest spectrum observed during the brightest gamma-ray state. The gamma-ray flares occurred before and during a slow rising trend in the radio, but no direct association between gamma-ray and

  9. Fossil shell emission in dying radio loud AGNs

    NASA Astrophysics Data System (ADS)

    Kino, M.; Ito, H.; Kawakatu, N.; Orienti, M.; Nagai, H.; Wajima, K.; Itoh, R.

    2016-02-01

    We investigate shell emission associated with dying radio loud AGNs. First, based on our recent work by Ito et al. (2015), we describe the dynamical and spectral evolution of shells after stopping the jet energy injection. We find that the shell emission overwhelms that of the radio lobes soon after stopping the jet energy injection because fresh electrons are continuously supplied into the shell via the forward shock, while the radio lobes rapidly fade out without jet energy injection. We find that such fossil shells can be a new class of target sources for SKA telescope. Next, we apply the model to the nearby radio source 3C84. Then, we find that the fossil shell emission in 3C84 is less luminous in the radio band while it is bright in the TeV γ-ray band and can be detectable by CTA. Data from STELLA

  10. The intrinsic line width of the Fe K α line of AGN

    NASA Astrophysics Data System (ADS)

    Liu, Jiren

    2016-11-01

    X-ray fluorescent lines are unique features of the reflection spectrum of the cold torus when irradiated by the central AGN. Their intrinsic line widths can be used to probe the line-emitting region. The line widths of the Fe \\Ka line measured from the first order Chandra High Energy Grating (HEG) spectra are $3-5$ times larger than those measured with the Si \\Ka line for Circinus, Mrk 3, and NGC 1068. Because the observed Si \\Ka and Fe \\Ka lines are not necessarily coming from the same physical region, it is uncertain whether the line widths of the Fe \\Ka line are over-estimated or not. We measured the intrinsic line widths of the Fe \\Ka line of several nearby bright AGN using the second and third order Chandra HEG spectra, whose spectral resolutions are better than the first order data. We found the measured widths are all smaller than those from the first order data. The results clearly show that the widths of the Fe \\Ka line measured from the first order HEG data are over-estimated. It indicates that the Fe \\Ka lines of the studied sources are originating from regions around the cold dusty torus.

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

    NASA Technical Reports Server (NTRS)

    Schmidt, Gary D.

    2005-01-01

    This award represents the second phase of an X-ray study of QSOs that are heavily obscured in the optical/near-IR. An earlier survey revealed that these active galactic nuclei (AGN) are also typically strongly absorbed at high photon energies, but the enhanced sensitivity of XMM-Newton provided for the first time the opportunity to measure the spectral indices of individual sources and to test the possibility that obscured AGN are responsible for a substantial portion of the cosmic X-ray background (CXRB). The new observations confirm and greatly extend the earlier results. Substantial intervening absorbing material is detected for 3 of the sources, and 2 additional targets show hard power-law continua. In addition, soft X-ray excesses are detected in 3 of sources, indicating the presence of extended regions of ionized gas. This component is-particularly well-defined in the Type 1 source 2MASS2344+1221, allowing analysis and modeling at a level of detail unusual for such distant sources. An important finding that parallels conclusions from optical polarimetry is the lack of dependence of absorption on optical spectral class (Type 1 or 2). The combination of strong polarization and X-ray absorption in sources that show strong, broad emission lines indicates either a very small (nuclear) absorber or a favored viewing angle which allows the X-ray source to be covered but the surrounding broad emission-line region to be largely exposed. The observed spectral also indicate that obscured AGN of both Type 1 and 2 contribute significantly to the CXRB at higher X-ray energies.

  12. 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.

  13. ALMA 0.1-0.2 arcsec Resolution Imaging of the NGC 1068 Nucleus: Compact Dense Molecular Gas Emission at the Putative AGN Location

    NASA Astrophysics Data System (ADS)

    Imanishi, Masatoshi; Nakanishi, Kouichiro; Izumi, Takuma

    2016-05-01

    We present the results of our ALMA Cycle 2 high angular resolution (0.″1-0.″2) observations of the nuclear region of the nearby well-studied type-2 active galactic nucleus (AGN), NGC 1068, at HCN J = 3-2 and HCO+ J = 3-2 emission lines. For the first time, due to a higher angular resolution than previous studies, we clearly detected dense molecular gas emission at the putative AGN location, identified as a ˜1.1 mm (˜266 GHz) continuum emission peak, by separating this emission from brighter emission located at 0.″5-2.″0 on the eastern and western sides of the AGN. The estimated intrinsic molecular emission size and dense molecular mass, which are thought to be associated with the putative dusty molecular torus around an AGN, were ˜10 pc and ˜several × 105 M ⊙, respectively. HCN-to-HCO+ J = 3-2 flux ratios substantially higher than unity were found throughout the nuclear region of NGC 1068. The continuum emission displayed an elongated morphology along the direction of the radio jet located at the northern side of the AGN, as well as a weak spatially-resolved component at ˜2.″0 on the southwestern side of the AGN. The latter component most likely originated from star formation, with the estimated luminosity more than one order of magnitude lower than the luminosity of the central AGN. No vibrationally excited (v 2 = 1f) J = 3-2 emission lines were detected for HCN and HCO+ across the field of view.

  14. ALMA 0.1–0.2 arcsec Resolution Imaging of the NGC 1068 Nucleus: Compact Dense Molecular Gas Emission at the Putative AGN Location

    NASA Astrophysics Data System (ADS)

    俊, Masatoshi Imanishi (今 西 昌; 郎, Kouichiro Nakanishi (中 西 康 一; 磨, Takuma Izumi (泉 拓

    2016-05-01

    We present the results of our ALMA Cycle 2 high angular resolution (0.″1–0.″2) observations of the nuclear region of the nearby well-studied type-2 active galactic nucleus (AGN), NGC 1068, at HCN J = 3–2 and HCO+ J = 3–2 emission lines. For the first time, due to a higher angular resolution than previous studies, we clearly detected dense molecular gas emission at the putative AGN location, identified as a ˜1.1 mm (˜266 GHz) continuum emission peak, by separating this emission from brighter emission located at 0.″5–2.″0 on the eastern and western sides of the AGN. The estimated intrinsic molecular emission size and dense molecular mass, which are thought to be associated with the putative dusty molecular torus around an AGN, were ˜10 pc and ˜several × 105 M ⊙, respectively. HCN-to-HCO+ J = 3–2 flux ratios substantially higher than unity were found throughout the nuclear region of NGC 1068. The continuum emission displayed an elongated morphology along the direction of the radio jet located at the northern side of the AGN, as well as a weak spatially-resolved component at ˜2.″0 on the southwestern side of the AGN. The latter component most likely originated from star formation, with the estimated luminosity more than one order of magnitude lower than the luminosity of the central AGN. No vibrationally excited (v 2 = 1f) J = 3–2 emission lines were detected for HCN and HCO+ across the field of view.

  15. 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.

  16. Iron K Line Variability in the Low-Luminosity AGN NGC 4579

    NASA Technical Reports Server (NTRS)

    Terashima, Yuichi; Ho, Luis C.; Ptak, Andrew F.; Yaqoob, Tahir; Kunieda, Hideyo; Misaki, Kazutami; Serlemitsos, Peter J.; White, Nicholas E. (Technical Monitor)

    2000-01-01

    We present results of new ASCA observations of the low-luminosity AGN (LLAGN) NGC 4579 obtained in 1998 December 18 and 28, and we report on detection of variability of an iron K emission line. The X-ray luminosities in the 2-10 keV band for the two observations are nearly identical, L(sub X) approximately = 2 x 10(exp 4l) ergs/s, but they are approximately 35% larger than that measured in 1995 July by Terashima et al. (1998). An Fe K emission line is detected at 6.39 +/- 0.09 keV (source rest frame) which is lower than the line energy 6.73(sup +0.13, sub -0.12) keV in the 1995 observation. If we fit the Fe lines with a blend of two Gaussians centered at 6.4 keV and 6.73 KeV, the intensity of the 6.7 keV line decreased, while the intensity of the 6.4 keV line increased, within an interval of 3.5 years. This variability rules out thermal plasmas in the host galaxy as the origin of the ionized Fe line in this LLAGN. The detection and variability of the 6.4 keV line suggest that an optically thick standard accretion disk is present and subtends a large solid angle viewed from the nucleus at the Eddington ratio of L(sub Bol)/L(sub Eddington) approximately 2 x 10(exp -3) (Ho 1999). A broad disk-line profile is not clearly seen and the structure of the innermost part of accretion disk remains unclear.

  17. 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

  18. A high fraction of double-peaked narrow emission lines in powerful active galactic nuclei

    NASA Astrophysics Data System (ADS)

    Lyu, Yang; Liu, Xin

    2016-11-01

    1 per cent 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 harbouring a supermassive black hole (SMBH), and/or galactic-scale disc 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. 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.

  19. First systematic search for oxygen-line blobs at high redshift: Uncovering AGN feedback and star formation quenching

    SciTech Connect

    Yuma, Suraphong; Ouchi, Masami; Ono, Yoshiaki; Momose, Rieko; Drake, Alyssa B.; Simpson, Chris; Shimasaku, Kazuhiro; Nakajima, Kimihiko; Akiyama, Masayuki; Mori, Masao; Umemura, Masayuki

    2013-12-10

    We present the first systematic search for extended metal-line [O II] λλ3726, 3729 nebulae, or [O II] blobs (O IIBs), at z = 1.2 using deep narrowband imaging with a survey volume of 1.9 × 10{sup 5} Mpc{sup 3} on the 0.62 deg{sup 2} sky of Subaru-XMM Deep Survey (SXDS) field. We discover a giant O IIB, called 'O IIB 1', with a spatial extent over ∼75 kpc at a spectroscopic redshift of z = 1.18, and also identify a total of 12 O IIBs with a size of >30 kpc. Our optical spectrum of O IIB 1 presents [Ne V] λ3426 line at the 6σ level, indicating that this object harbors an obscured type-2 active galactic nucleus (AGN). The presence of gas outflows in this object is suggested by two marginal detections of Fe II λ2587 absorption and Fe II* λ2613 emission lines both of which are blueshifted at as large as 500-600 km s{sup –1}, indicating that the heating source of O IIB 1 is AGN or associated shock excitation rather than supernovae produced by starbursts. The number density of O IIB 1-type giant blobs is estimated to be ∼5 × 10{sup –6} Mpc{sup –3} at z ∼ 1.2, which is comparable with that of AGNs driving outflow at a similar redshift, suggesting that giant O IIBs are produced only by AGN activity. On the other hand, the number density of small O IIBs, 6 × 10{sup –5} Mpc{sup –3}, compared to that of z ∼ 1 galaxies in the blue cloud in the same M{sub B} range, may imply that 3% of star-forming galaxies at z ∼ 1 are quenching star formation through outflows involving extended [O II] emission.

  20. Exploring X-ray and radio emission of type 1 AGN up to z ~ 2.3

    NASA Astrophysics Data System (ADS)

    Ballo, L.; Heras, F. J. H.; Barcons, X.; Carrera, F. J.

    2012-09-01

    Context. X-ray emission from active galactic nuclei (AGN) is dominated by the accretion disk around a supermassive black hole. The radio luminosity, however, has not such a clear origin except in the most powerful sources where jets are evident. The origin (and even the very existence) of the local bi-modal distribution in radio-loudness is also a debated issue. Aims: By analysing X-ray, optical and radio properties of a large sample of type 1 AGN and quasars (QSOs) up to z > 2, where the bulk of this population resides, we aim to explore the interplay between radio and X-ray emission in AGN, in order to further our knowledge on the origin of radio emission, and its relation to accretion. Methods: We analyse a large (~800 sources) sample of type 1 AGN and QSOs selected from the 2XMMi XMM-Newton X-ray source catalogue, cross-correlated with the SDSS DR7 spectroscopic catalogue, covering a redshift range from z ~ 0.3 to z ~ 2.3. Supermassive black hole masses are estimated from the Mg ii emission line, bolometric luminosities from the X-ray data, and radio emission or upper limits from the FIRST catalogue. Results: Most of the sources accrete close to the Eddington limit and the distribution in radio-loudness does not appear to have a bi-modal behaviour. We confirm that radio-loud AGN are also X-ray loud, with an X-ray-to-optical ratio up to twice that of radio-quiet objects, even excluding the most extreme strongly jetted sources. By analysing complementary radio-selected control samples, we find evidence that these conclusions are not an effect of the X-ray selection, but are likely a property of the dominant QSO population. Conclusions: Our findings are best interpreted in a context where radio emission in AGN, with the exception of a minority of beamed sources, arises from very close to the accretion disk and is therefore heavily linked to X-ray emission. We also speculate that the radio-loud/radio-quiet dichotomy might either be an evolutionary effect that

  1. 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

  2. Gamma-ray emitting narrow-line Seyfert 1 galaxies and their place in the AGN zoo

    NASA Astrophysics Data System (ADS)

    D'Ammando, Filippo; Orienti, Monica; Finke, Justin; Giroletti, Marcello; Larsson, Josefin

    2016-08-01

    Relativistic jets are usually produced by radio-loud AGN hosted in giant elliptical galaxies such as blazars and radio galaxies. The discovery by Fermi-LAT of variable gamma-ray emission from narrow-line Seyfert 1 (NLSy1) galaxies revealed the presence of a new class of AGN with relativistic jets. Considering that NLSy1 are usually hosted in spiral galaxies, this finding poses intriguing questions about the nature of these objects and the formation of relativistic jets. In this talk I discuss the radio-to-gamma-ray properties of the gamma-ray NLSy1 detected during the first 7 years of Fermi operation, the observations of their host galaxies, and the estimation of their black hole masses.

  3. The host galaxies and narrow-line regions of four double-peaked [OIII] AGNs

    SciTech Connect

    Villforth, Carolin; Hamann, Fred

    2015-03-01

    Major gas-rich mergers of galaxies are expected to play an important role in triggering and fueling luminous active galactic nuclei (AGNs). The mechanism of AGN fueling during mergers, however, remains poorly understood. We present deep multi-band (u/r/z) imaging and long-slit spectroscopy of four double-peaked [OIII] emitting AGNs. This class of object is likely associated with either kiloparsec-separated binary AGNs or final stage major mergers, although AGNs with complex narrow-line regions (NLRs) are known contaminants. Such objects are of interest since they represent the onset of AGN activity during the merger process. Three of the four double-peaked [OIII] emitters studied have been confirmed as major mergers using near-infrared imaging and one is a confirmed X-ray binary AGN. All AGNs are luminous, radio-quiet to radio-intermediate, and have redshifts of 0.1AGN suggests that the merger of a binary black hole can take longer than 1 Gyr. All AGNs hosted by merging galaxies have companions at distances ⩽150 kpc. The NLRs have large sizes (10 kpc < r < 100 kpc) and consist of compact clumps with considerable relative velocities between components (∼200–650 km s{sup −1}). We detect broad, predominantly blue, wings with velocities up to ∼1500 km s{sup −1} in [OIII], indicative of powerful outflows. The outflows are compact (<5 kpc) and co-spatial with nuclear regions showing considerable reddening, consistent with enhanced star formation. One source shows an offset between gas and stellar kinematics, consistent with either a bipolar flow or a counter-rotating gas disk. In all other sources, the ionized gas

  4. 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.

  5. Obscured AGN

    NASA Technical Reports Server (NTRS)

    Ptak, Andrew

    2011-01-01

    Many obscured AGN show evidence of significant starburst emission dominating below 2 keV. Therefore wide-field X-ray surveys sensitive enough to luminosities below approximately 10^42 ergs per second will result in detections of galaxies with contributions of both obscured AGN and starburst emission. We will discuss Bayesian approaches to assessing the relative contribution of each component, minimizing survey biases and using the resultant posterior probabilities for the AGN and starburst components to determine their evolution.

  6. Optically-selected AGN

    NASA Astrophysics Data System (ADS)

    Richard, Gordon

    2016-08-01

    will discuss the selection and properties of optically-selected AGN as contrasted with other multi-wavelength investigations. While optical surveys are able to identify *more* AGNs than other wavelengths, this size comes with a bias towards brighter, unobscured sources. Although optical surveys are not ideal for probing obscured AGNs, I will discuss how they can guide our search for them. The bias towards unobscured sources in the optical is partially mitigated, however, by an increase in information content for the sources that *are* identified---in the form of physics probed by the combination of optical continuum, absorption, and emission. An example is the ability to estimate the mass of AGNs based on the optical/UV emission lines. I will discuss the range of mass (and accretion rate) probed by the optical in addition to serious biases in the black hole mass scaling relations that corrupt these estimates at high redshift.

  7. An Atlas of Starburst Galaxy Emission Lines

    NASA Astrophysics Data System (ADS)

    Meskhidze, Helen; Richardson, Chris T.; Ferland, Gary J.

    2015-01-01

    Recent observations of high ionization lines (e.g. [Ne V] and He II λ4686) from star-forming regions have prompted a need to study the production mechanisms of these high ionization lines. Our study addresses the following questions: 1. What are specific cloud parameters that influence the strength of emission lines in starburst galaxies? 2. How can these parameters be tuned in simulations to match observations? We adopt the locally optimally emitting cloud model, a model previously used to study AGN, for our study of star-forming regions. We present the results of hundreds of photoionization simulations spanning 15 orders of magnitude in hydrogen ionizing photon flux and 10 orders of magnitude in hydrogen density. We vary both properties of the starbursts (SEDs, evolutionary histories, ages), as well as cloud properties (such as the abundances and metallicity), tracking nearly 100 emission lines ranging from the UV to the near IR. Finally, we compare these results to the results of other studies on star-forming regions. The results of our photoionization calculations should prove useful for the analysis of starburst galaxy emission-line data.

  8. CORONAL EMISSION LINES AS THERMOMETERS

    SciTech Connect

    Judge, Philip G.

    2010-01-10

    Coronal emission-line intensities are commonly used to measure electron temperatures using emission measure and/or line ratio methods. In the presence of systematic errors in atomic excitation calculations and data noise, the information on underlying temperature distributions is fundamentally limited. Increasing the number of emission lines used does not necessarily improve the ability to discriminate between different kinds of temperature distributions.

  9. Aborted jets and the X-ray emission of radio-quiet AGNs

    NASA Astrophysics Data System (ADS)

    Ghisellini, G.; Haardt, F.; Matt, G.

    2004-01-01

    We propose that radio-quiet quasars and Seyfert galaxies have central black holes powering outflows and jets which propagate only for a short distance, because the velocity of the ejected material is smaller than the escape velocity. We call them ``aborted" jets. If the central engine works intermittently, blobs of material may be produced, which can reach a maximum radial distance and then fall back, colliding with the blobs produced later and still moving outwards. These collisions dissipate the bulk kinetic energy of the blobs by heating the plasma, and can be responsible (entirely or at least in part) for the generation of the high energy emission in radio-quiet objects. This is alternative to the more conventional scenario in which the X-ray spectrum of radio-quiet sources originates in a hot (and possibly patchy) corona above the accretion disk. In the latter case the ultimate source of energy of the emission of both the disk and the corona is accretion. Here we instead propose that the high energy emission is powered also by the extraction of the rotational energy of the black hole (and possibly of the disk). By means of Montecarlo simulations we calculate the time dependent spectra and light curves, and discuss their relevance to the X-ray spectra in radio-quiet AGNs and galactic black hole sources. In particular, we show that time variability and spectra are similar to those observed in Narrow Line Seyfert 1 galaxies.

  10. Statistics of broad relativistic lines in AGN: a counts- and flux-limited sampl

    NASA Astrophysics Data System (ADS)

    Guainazzi, Matteo

    2006-10-01

    We propose to observe 10 X-ray unabsorbed Active Galactic Nuclei (AGN) extracted from the RXTE Slew Survey (XSS). We aim at completing the XMM-Newton coverage of a flux-limited [2-10 keV flux > 1 mCrab] sub-sample of the XSS with enough statistical quality to unambiguously establish the presence of a relativistically broadened K-alpha iron line in the spectrum of each individual object. Measuring the fraction of local universe AGN where effects due to a relativistic accretion disk are detected, along with the accurate determination of the accretion flow physical properties, will allow us to tell if and how the standard paradigm needs to be modified to explain the origin of the energy output in AGN. The total requested time is 975 ks

  11. PEARS Emission Line Galaxies

    NASA Technical Reports Server (NTRS)

    Pirzkal, Nor; Rothberg, Barry; Ly, Chun; Rhoads, James E.; Malhotra, Sangeeta; Grogin, Norman A.; Dahlen, Tomas; Meurer, Gerhardt R.; Walsh, Jeremy; Hathi, Nimish P.; Cohen, Seth; Belini, Andrea; Holwerda, Benne W.; Straughn, Amber; Mechtley, Matthew

    2012-01-01

    We present a full analysis of the Probing Evolution And Reionization Spectroscopically (PEARS) slitless grism spectroscopic data obtained vl'ith the Advanced Camera for Surveys on HST. PEARS covers fields within both the Great Observatories Origins Deep Survey (GOODS) North and South fields, making it ideal as a random surveY of galaxies, as well as the availability of a wide variety of ancillary observations to support the spectroscopic results. Using the PEARS data we are able to identify star forming galaxies within the redshift volume 0 < z < 1.5. Star forming regions in the PEARS survey are pinpointed independently of the host galaxy. This method allOW8 us to detect the presence of multiple emission line regions (ELRs) within a single galaxy. 1162 [OII], [OIII] and/or H-alpha emission lines have been identified in the PEARS sample of approx 906 galaxies down to a limiting flux of approx 10 - 18 erg/s/sq cm . The ELRs have also been compared to the properties of the host galaxy, including morphology, luminosity, and mass. From this analysis we find three key results: 1) The computed line luminosities show evidence of a flattening in the luminosity function with increasing redshift; 2) The star forming systems show evidence of disturbed morphologies, with star formation occurring predominantly within one effective (half-light) radius. However, the morphologies show no correlation with host stellar mass; and 3) The number density of star forming galaxies with M(*) >= 10(exp 9) Solar M decreases by an order of magnitude at z<=0.5 relative to the number at 0.5 < z < 0.9 in support of the argument for galaxy downsizing.

  12. THE LICK AGN MONITORING PROJECT: BROAD-LINE REGION RADII AND BLACK HOLE MASSES FROM REVERBERATION MAPPING OF Hbeta

    SciTech Connect

    Bentz, Misty C.; Walsh, Jonelle L.; Barth, Aaron J.; Baliber, Nairn; Bennert, Vardha Nicola; Greene, Jenny E.; Hidas, Marton G.; Canalizo, Gabriela; Hiner, Kyle D.; Filippenko, Alexei V.; Ganeshalingam, Mohan; Lee, Nicholas; Li, Weidong; Serduke, Frank J. D.; Silverman, Jeffrey M.; Steele, Thea N.; Gates, Elinor L.; Malkan, Matthew A.; Minezaki, Takeo; Sakata, Yu

    2009-11-01

    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 approx10{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 Hbeta emission. We present here the light curves for all the objects in this sample and the subsequent Hbeta time lags for the nine objects where these measurements were possible. The Hbeta lag time is directly related to the size of the broad-line region (BLR) in AGNs, and by combining the Hbeta lag time with the measured width of the Hbeta emission line in the variable part of the spectrum, we determine the virial mass of the central supermassive black hole in these nine AGNs. The absolute calibration of the black hole masses is based on the normalization derived by Onken et al., which brings the masses determined by reverberation mapping into agreement with the local M {sub BH}-sigma{sub *}relationship for quiescent galaxies. We also examine the time lag response as a function of velocity across the Hbeta line profile for six of the AGNs. The analysis of four leads to rather ambiguous results with relatively flat time lags as a function of velocity. However, SBS 1116+583A exhibits a symmetric time lag response around the line center reminiscent of simple models for circularly orbiting BLR clouds, and Arp 151 shows an asymmetric profile that is most easily explained by a simple gravitational infall model. Further investigation will be necessary to fully understand the constraints placed on the physical models of the BLR by the velocity-resolved response

  13. EDDINGTON RATIO DISTRIBUTION OF X-RAY-SELECTED BROAD-LINE AGNs AT 1.0 < z < 2.2

    SciTech Connect

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

    2015-12-20

    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.

  14. On the emitting region of X-ray fluorescent lines around Compton-thick AGN

    NASA Astrophysics Data System (ADS)

    Liu, Jiren

    2016-06-01

    X-ray fluorescent lines are unique features of the reflection spectrum of the torus when irradiated by the central active galactic nuclei (AGN). Their intrinsic line width can be used to probe the line-emitting region. Previous studies have focused on the Fe K α line at 6.4 keV, which is the most prominent fluorescent line. These studies, however, are limited by the spectral resolution of currently available instruments, the best of which is ˜1860 km s-1 afforded by the Chandra High-Energy Grating (HEG). The HEG spectral resolution is improved by a factor of 4 at 1.74 keV, where the Si K α line is located. We measured the full width at half-maximum of the Si K α line for Circinus, Mrk 3, and NGC 1068, which are 570 ± 240, 730 ± 320, and 320 ± 280 km s-1, respectively. They are 3-5 times smaller than those measured with the Fe K α line previously. It shows that the intrinsic widths of the Fe K α line are most likely to be overestimated. The measured widths of the Si K α line put the line-emitting region outside the dust sublimation radius in these galaxies. It indicates that for Compton-thick AGN, the X-ray fluorescence material are likely to be the same as the dusty torus emitting in the infrared band.

  15. RXTE, Chandra, and XMM Spectroscopy of the Fe-K Lines and Compton Reflection in Type 1 AGN

    NASA Technical Reports Server (NTRS)

    Yaqoob, Tahir

    2004-01-01

    This award pertains to an RXTE observation of the Seyfert 1 galaxy Akn 120. The purpose of the observation was to measure the Fe-K emission line and the Compton reflection continuum with RXTE, simultaneously with Chandra and XMM. Such measurements can severely constrain accretion disk models of the central engine since the Fe-K line emission and Compton reflection are intimately related in terms of the physics of X-ray reprocessing in optically-thick matter. Akn 120 was selected for this study because it is amongst the brightest AGN in its class and has a particularly strong and apparently broad Fe-K emission line. The results could then also be used to lay the ground work for even higher resolution studies with Astro-E2. Unfortunately, the Chandra observation was not performed but a contemporaneous XMM observation was performed by another group of researchers. Those data recently became public and can be compared with the RXTE data. In addition, non-contemporaneous observations with other missions do still provide additional important constraints (for example any non-varying line or continuum emission components can be established and used to reject or preserve various model scenarios). We analyzed the RXTE data and found a strong Fe-K emission line (resolved even with the poor resolution of RXTE), and a strong Compton-reflection continuum (see Fig. l(a)). We found that the results of archival ASCA data on Akn 120 had not been published in the literature so we analyzed the ASCA data too, in order to compare with the new RXTE data. Fig. l(b) shows that the ASCA data also reveal a strong, broad FeK emission line (but the data are not sensitive to the Compton-reflection continuum). We compared our spectral fitting results for the RXTE and ASCA data with the results from XMM and from previous RXTE observations.

  16. A study for testing the Kerr metric with AGN iron line eclipses

    NASA Astrophysics Data System (ADS)

    Cárdenas-Avendaño, Alejandro; Jiang, Jiachen; Bambi, Cosimo

    2016-04-01

    Recently, two of us have studied iron line reverberation mapping to test black hole candidates, showing that the time information in reverberation mapping can better constrain the Kerr metric than the time-integrated approach. Motivated by this finding, here we explore the constraining power of another time-dependent measurement: an AGN iron line eclipse. An obscuring cloud passes between the AGN and the distant observer, covering different parts of the accretion disk at different times. Similar to the reverberation measurement, an eclipse might help to better identify the relativistic effects affecting the X-ray photons. However, this is not what we find. In our study, we employ the Johannsen-Psaltis parametrisation, but we argue that our conclusions hold in a large class of non-Kerr metrics. We explain our results pointing out an important difference between reverberation and eclipse measurements.

  17. 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.

  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

    2016-11-01

    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 average equivalent width 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 DIFFERENCE IN NARROW Fe K{alpha} LINE EMISSION BETWEEN SEYFERT 1 AND SEYFERT 2 GALAXIES

    SciTech Connect

    Liu Teng; Wang Junxian E-mail: jxw@ustc.edu.c

    2010-12-20

    We compile a sample of 89 Seyfert galaxies with both [O IV] 25.89 {mu}m line luminosities observed by Spitzer IRS and X-ray spectra observed by XMM-Newton EPIC. Using [O IV] emission as a proxy for active galactic nucleus (AGN) intrinsic luminosity, we find that although type 2 AGNs have higher line equivalent widths, the narrow Fe K{alpha} lines in Compton-thin and Compton-thick Seyfert 2 galaxies are 2.9{sup +0.8}{sub -0.6} and 5.6{sup +1.9}{sub -1.4} times weaker in terms of luminosity than Seyfert 1 galaxies, respectively. This indicates that different correction factors need to be applied for various types of AGNs before the narrow Fe K{alpha} line luminosity could serve as an intrinsic AGN luminosity indicator. We also find that Seyfert 1 galaxies in our sample have on average marginally larger line widths and higher line centroid energies, suggesting contamination from highly ionized Fe line or broader line emission from much smaller radius, but this effect is too weak to explain the large difference in narrow Fe K{alpha} line luminosity between type 1 and type 2 AGNs. This is the first observational evidence showing that the narrow Fe K{alpha} line emission in AGNs is anisotropic. The observed difference is consistent with theoretical calculations assuming a smoothly distributed obscuring torus and could provide independent constraints on the clumpiness of the torus.

  20. Plasma simulations of emission line regions in high energy environments

    NASA Astrophysics Data System (ADS)

    Richardson, Chris T.

    This dissertation focuses on understanding two different, but in each case extreme, astrophysical environments: the Crab Nebula and emission line galaxies. These relatively local objects are well constrained by observations and are test cases of phenomena seen at high-z where detailed observations are rare. The tool used to study these objects is the plasma simulation code known as Cloudy. The introduction provides a brief summary of relevant physical concepts in nebular astrophysics and presents the basic features and assumptions of Cloudy. The first object investigated with Cloudy, the Crab Nebula, is a nearby supernova remnant that previously has been subject to photoionization modeling to reproduce the ionized emission seen in the nebula's filamentary structure. However, there are still several unanswered questions: (1) What excites the H2 emitting gas? (2) How much mass is in the molecular component? (3) How did the H2 form? (4) What is nature of the dust grains? A large suite of observations including long slit optical and NIR spectra over ionized, neutral and molecular gas in addition to HST and NIR ground based images constrain a particularly bright region of H2 emission, Knot 51, which exhibits a high excitation temperature of ˜3000 K. Simulations of K51 revealed that only a trace amount of H2 is needed to reproduce the observed emission and that H2 forms through an uncommon nebular process known as associative detachment. The final chapters of this dissertation focus on interpreting the narrow line region (NLR) in low-z emission line galaxies selected by a novel technique known as mean field independent component analysis (MFICA). A mixture of starlight and radiation from an AGN excites the gas present in galaxies. MFICA separates galaxies over a wide range of ionization into subsets of pure AGN and pure star forming galaxies allowing simulations to reveal the properties responsible for their observed variation in ionization. Emission line ratios can

  1. The Emission-Line Universe

    NASA Astrophysics Data System (ADS)

    Cepa, Jordi

    2012-02-01

    Preface; 1. What can emission lines tell us? G. Stasińska; 2. The observer's perspective: emission-line surveys M. Giavalisco; 3. The astrophysics of early galaxy formation P. Madau; 4. Primeval galaxies D. Schaerer; 5. Active galactic nuclei B. M. Peterson; 6. Chemical evolution F. Matteucci; 7. Galactic sources of emission lines S. Eikenberry; 8. Narrow band imaging S. Pascual and B. Cedrés; 9. Long-slit spectroscopy M. Sánchez and A. M. García; 10. Basic principles of tunable filters H. Castañeda and A. Bongiovanni.

  2. The Emission-Line Universe

    NASA Astrophysics Data System (ADS)

    Cepa, Jordi

    2008-11-01

    Preface; 1. What can emission lines tell us? G. Stasińska; 2. The observer's perspective: emission-line surveys M. Giavalisco; 3. The astrophysics of early galaxy formation P. Madau; 4. Primeval galaxies D. Schaerer; 5. Active galactic nuclei B. M. Peterson; 6. Chemical evolution F. Matteucci; 7. Galactic sources of emission lines S. Eikenberry; 8. Narrow band imaging S. Pascual and B. Cedrés; 9. Long-slit spectroscopy M. Sánchez and A. M. García; 10. Basic principles of tunable filters H. Castañeda and A. Bongiovanni.

  3. 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.

  4. Quantifying correlations between galaxy emission lines and stellar continua

    NASA Astrophysics Data System (ADS)

    Beck, Róbert; Dobos, László; Yip, Ching-Wa; Szalay, Alexander S.; Csabai, István

    2016-03-01

    We analyse the correlations between continuum properties and emission line equivalent widths of star-forming and active galaxies from the Sloan Digital Sky Survey. Since upcoming large sky surveys will make broad-band observations only, including strong emission lines into theoretical modelling of spectra will be essential to estimate physical properties of photometric galaxies. We show that emission line equivalent widths can be fairly well reconstructed from the stellar continuum using local multiple linear regression in the continuum principal component analysis (PCA) space. Line reconstruction is good for star-forming galaxies and reasonable for galaxies with active nuclei. We propose a practical method to combine stellar population synthesis models with empirical modelling of emission lines. The technique will help generate more accurate model spectra and mock catalogues of galaxies to fit observations of the new surveys. More accurate modelling of emission lines is also expected to improve template-based photometric redshift estimation methods. We also show that, by combining PCA coefficients from the pure continuum and the emission lines, automatic distinction between hosts of weak active galactic nuclei (AGNs) and quiescent star-forming galaxies can be made. The classification method is based on a training set consisting of high-confidence starburst galaxies and AGNs, and allows for the similar separation of active and star-forming galaxies as the empirical curve found by Kauffmann et al. We demonstrate the use of three important machine learning algorithms in the paper: k-nearest neighbour finding, k-means clustering and support vector machines.

  5. High-velocity Bipolar Molecular Emission from an AGN Torus

    NASA Astrophysics Data System (ADS)

    Gallimore, Jack F.; Elitzur, Moshe; Maiolino, Roberto; Marconi, Alessandro; O'Dea, Christopher P.; Lutz, Dieter; Baum, Stefi A.; Nikutta, Robert; Impellizzeri, C. M. V.; Davies, Richard; Kimball, Amy E.; Sani, Eleonora

    2016-09-01

    We have detected in ALMA observations CO J=6\\to 5 emission from the nucleus of the Seyfert galaxy NGC 1068. The low-velocity (up to ±70 km s-1 relative to systemic) CO emission resolves into a 12 × 7 pc structure, roughly aligned with the nuclear radio source. Higher-velocity emission (up to ±400 km s-1) is consistent with a bipolar outflow in a direction nearly perpendicular (≃80°) to the nuclear disk. The position-velocity diagram shows that in addition to the outflow, the velocity field may also contain rotation about the disk axis. These observations provide compelling evidence in support of the disk-wind scenario for the active galactic nucleus obscuring torus.

  6. X-ray fluorescent lines from the Compton-thick AGN in M51

    NASA Astrophysics Data System (ADS)

    Xu, Weiwei; Liu, Zhu; Gou, Lijun; Liu, Jiren

    2016-01-01

    The cold disc/torus gas surrounding active galactic nuclei (AGN) emits fluorescent lines when irradiated by hard X-ray photons. The fluorescent lines of elements other than Fe and Ni are rarely detected due to their relative faintness. We report the detection of Kα lines of neutral Si, S, Ar, Ca, Cr, and Mn, along with the prominent Fe Kα, Fe Kβ, and Ni Kα lines, from the deep Chandra observation of the low-luminosity Compton-thick AGN in M51. The Si Kα line at 1.74 keV is detected at ˜3σ, the other fluorescent lines have a significance between 2 and 2.5 σ, while the Cr line has a significance of ˜1.5σ. These faint fluorescent lines are made observable due to the heavy obscuration of the intrinsic spectrum of M51, which is revealed by NuSTAR observation above 10 keV. The hard X-ray continuum of M51 from Chandra and NuSTAR can be fitted with a power-law spectrum with an index of 1.8, reprocessed by a torus with an equatorial column density of NH ˜ 7 × 1024 cm-2 and an inclination angle of 74°. This confirms the Compton-thick nature of the nucleus of M51. The relative element abundances inferred from the fluxes of the fluorescent lines are similar to their solar values, except for Mn, which is about 10 times overabundant. It indicates that Mn is likely enhanced by the nuclear spallation of Fe.

  7. The galactic dynamo, the helical force free field and the emissions of AGN

    SciTech Connect

    Colgate, S.; Li, Hui

    1997-05-01

    We present a theory relating the central galactic black hole (BH) formation to the galactic dynamo through an accretion disk. The associated AGN emissions and the collimated radio sources are then a result of the dynamo process. A unified theory of quasar and BL-Lac formation (hereafter AGN) starts with the collapse of damped Lyman-alpha clouds, presumably proto-galaxies, which then evolve to a central disk and black hole, (BH). An alpha - omega dynamo forms in this accretion disk where the augmentation of the poloidal field from the toroidal field depends upon star disk collisions. The winding number of the inner most orbit of the disk is so large, tilde 10 to the 11th power that the total gain of the dynamo is semi-infinite, and the original seed field of no consequence. The total magnetic flux produced is tilde 10000 times that of the galaxy, sufficient to explain the much larger flux of clusters. The semi-infinite gain of the dynamo implies that the field saturates at the dynamic stress so that most of the free energy of formation of the BH is carried off as magnetic energy in the form of a magnetic helix. The dissipation of this magnetic energy leads to the unique emission spectrum of AGN as well as the equally startling collimated radio and optical sources.

  8. The Covering Factor of Warm Dust in Weak Emission-line Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Zhang, Xudong; Liu, Yuan

    2016-10-01

    Weak emission-line active galactic nuclei (WLAGNs) are radio-quiet active galactic nuclei (AGNs) that have nearly featureless optical spectra. We investigate the ultraviolet to mid-infrared spectral energy distributions of 73 WLAGNs (0.4 < z < 3) and find that most of them are similar to normal AGNs. We also calculate the covering factor of warm dust of these 73 WLAGNs. No significant difference is indicated by a KS test between the covering factor of WLAGNs and normal AGNs in the common range of bolometric luminosity. The implication for several models of WLAGNs is discussed. The super-Eddington accretion is unlikely to be the dominant reason for the featureless spectrum of a WLAGN. The present results are still consistent with the evolution scenario, i.e., WLAGNs are in a special stage of AGNs.

  9. 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.

  10. Radio-Quiet Quasars in the VIDEO Survey: Evidence for AGN-powered radio emission below 1 mJy

    NASA Astrophysics Data System (ADS)

    White, Sarah; Jarvis, Matt; Haeussler, Boris; Maddox, Natasha

    2015-01-01

    Several lines of evidence suggest that the interaction between active galactic nucleus (AGN) activity and star formation is responsible for the co-evolution of black hole mass with galaxy bulge mass. Therefore studying this interplay is crucial to our understanding of galaxy formation and evolution. The new generation of radio surveys are able to play a key role in this area, as both processes produce radio emission.We use a combination of optical and near-infrared photometry to select a sample of 72 quasars from the VISTA Deep Extragalactic Observations (VIDEO) Survey, over 1 deg2. The depth of VIDEO allows us to study very low accretion rates and/or lower-mass black holes. 26% of the candidate quasar sample has been spectroscopically confirmed using the Southern African Large Telescope and the VIMOS VLT Deep Survey. We then use a radio-stacking technique to sample below the nominal flux-density threshold of existing Very Large Array data at 1.4 GHz. In agreement with other work, we show that a power-law fit to the radio number counts is inadequate, with an upturn in the counts being observed at these faint luminosities. Previous authors attribute this to an emergent star-forming population. However, by comparing radio emission from our quasars with that from a control sample of galaxies, we suggest that this emission is predominantly caused by accretion activity. Further support for an AGN origin is provided by a comparison of two independent estimates of star formation rate. These findings have important implications for modelling radio populations below 1 mJy, which is necessary for the development of the Square Kilometre Array.

  11. The Nature of Soft X-ray Emission in Obscured AGN

    NASA Astrophysics Data System (ADS)

    Guainazzi, M.

    2006-08-01

    We present results of a high-resolution soft X-ray (0.2 - 2 keV) spectroscopic study on a sample of 66 nearby obscured AGN observed by the Reflection Grating Spectrometer (RGS) on board XMM-Newton. This is the largest sample ever studied with this technique so far. The main conclusions of our study can be summarized as follows: a) narrow Radiative Recombination Continua are detected in 40% of the objects in our sample; in 27% their width is ≤ 10 eV; b) higher order transitions are generally enhanced with respect to pure photoionization, indicating that resonant scattering plays an important role in the ionization/excitation balance. These results support the scenario whereby the active nucleus is responsible for the X-ray 'soft excess' almost ubiquitously observed in nearby obscured AGN via photoionization of circumnuclear gas. They confirm on a statistical basis the conclusions drawn from the detailed study of the brightest spectra in the sample. Furthermore, we propose a criterion to statistically discriminate between AGN-photoionized sources and starbursts galaxies, based on intensity of the forbidden component of the OVII He-alpha triplet (once normalized to the OVIII Ly-alpha) coupled with the integrated luminosity in He-like and H-like oxygen lines.

  12. Mid-infrared interferometry of 23 AGN tori: On the significance of polar-elongated emission

    NASA Astrophysics Data System (ADS)

    López-Gonzaga, N.; Burtscher, L.; Tristram, K. R. W.; Meisenheimer, K.; Schartmann, M.

    2016-06-01

    Context. Detailed high-resolution studies of active galactic nuclei (AGN) with mid-infrared (MIR) interferometry have revealed parsec-sized dust emission that is elongated in the polar direction in four sources. Aims: Using a larger, coherently analyzed sample of AGN observed with MIR interferometry, we aim to identify elongated MIR emission in a statistical sample of sources. More specifically, we wish to determine if there is indeed a preferred direction of the elongation and whether this direction is consistent with a torus-like structure or with a polar emission. Methods: We investigated the significance of the detection of an elongated shape in the MIR emission by fitting elongated Gaussian models to the interferometric data at 12 μm. We paid special attention to (1) the uncertainties caused by an inhomogeneous (u,v) coverage; (2) the typical errors in the measurements; and (3) the spatial resolution achieved for each object. Results: From our sample of 23 sources, we are able to find elongated parsec-scale, MIR emission in five sources: three type 2s, one type 1i, and one type 1. Elongated emission in four of these sources has been published before; NGC 5506 is a new detection. The observed axis ratios are typically around 2 and the position angle of the 12 μm emission for all the elongated sources always seems to be closer to the polar axis of the system than to the equatorial axis. Two other objects, NGC 4507 and MCG-5-23-16, with reasonably well-mapped (u,v) coverage and good signal-to-noise ratios, appear to have a less elongated 12 μm emission. Conclusions: Our finding that sources showing elongated MIR emission are preferentially extended in polar direction sets strong constraints on torus models or implies that both the torus and NLR/outflow region have to be modeled together. In addition, models used for SED fitting will have to be revised to include emission from polar dust.

  13. WISE J233237.05-505643.5: A Double-Peaked Broad-Lined AGN with Spiral-Shaped Radio Morphology

    NASA Technical Reports Server (NTRS)

    Tsai, Chao Wei; Jarrett, Thomas H.; Stern, Daniel; Emonts, Bjorn; Barrows, R. Scott; Assef, Roberto J.; Norris, Ray P.; Eisenhardt, Peter R. M.; Lonsdale, Carol; Blain, Andrew W.; Benford, Dominic J.; Wu, Jingwen; Stalder, Brian; Stubbs, Christopher W.; High, F. William; Li, K. L.; Kong, Albert K. H.

    2013-01-01

    We present radio continuum mapping, optical imaging and spectroscopy of the newly discovered double-peaked broad-lined AGN WISE J233237.05-505643.5 at redshift z = 0.3447. This source exhibits an FR-I and FR-II hybrid-morphology, characterized by bright core, jet, and Doppler-boosted lobe structures in ATCA continuum maps at 1.5, 5.6, and 9 GHz. Unlike most FR-II objects, W2332-5056 is hosted by a disk-like galaxy. The core has a projected 5" linear radio feature that is perpendicular to the curved primary jet, hinting at unusual and complex activity within the inner 25 kpc. The multi-epoch optical-near-IR photometric measurements indicate significant variability over a 3-20 year baseline from the AGN component. Gemini-South optical data shows an unusual double-peaked emission-line features: the centroids of the broad-lined components of H-alpha and H-beta are blueshifted with respect to the narrow lines and host galaxy by approximately 3800 km/s. We examine possible cases which involve single or double supermassive black holes in the system, and discuss required future investigations to disentangle the mystery nature of this system.

  14. Emission Line Stars in Andromeda

    NASA Astrophysics Data System (ADS)

    Dalcanton, Julianne

    2014-10-01

    Elucidating the physics that drives production of emission lines in a wide variety of stellar sources is hampered by the relatively small, heterogeneous available samples. We propose to construct a large, deep, homogeneous sample of more than 10,000 emission line stars in M31, by adding H-alpha imaging to existing data from the Panchromatic Hubble Andromeda Treasury (PHAT), in regions targeted to contain large numbers of massive young stellar clusters. This program will deliver the statistics needed to determine the prevalence of Be disk systems as a function of age and the rate of dramatic disk-loss/disk-renewal episodes. The survey will also provide a key opportunity to identify Symbiotic stars from a well characterized dataset, and diagnose why the current rate of observed symbiotic stars is several orders of magnitude less than that predicted by theory. Our program will also serve as a critical, deep legacy product for the broader community interested in other emission line stars such as Wolf-Rayet stars, PNe, and luminous M(e) stars.

  15. 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.

  16. Molecular line emission in NGC 1068 imaged with ALMA

    NASA Astrophysics Data System (ADS)

    Garcia-Burillo, S.

    2015-09-01

    We investigate the fueling and the feedback of star formation and nuclear activity in NGC1068, a nearby Seyfert 2 barred galaxy, by analyzing the distribution and kinematics of the molecular gas in the disk. We have used ALMA to map the emission of a set of dense molecular gas tracers and their underlying continuum emission in the central r=2 kpc of NGC1068 with spatial resolutions 0.3"-0.5" (20-35 pc). Molecular line and dust continuum emissions are detected from a r=200 pc off-centered circumnuclear disk (CND), from the 2.6 kpc-diameter bar region, and from the r=1.3 kpc starburst (SB) ring. We used the dust continuum fluxes measured by ALMA together with NIR/MIR data to constrain the properties of the putative torus using CLUMPY models and found a torus radius of 20(6,-10)pc. The gas kinematics from r=50 pc out to r=400 pc reveal a massive outflow in all molecular tracers. The tight correlation between the ionized gas outflow, the radio jet and the occurrence of outward motions in the disk suggests that the outflow is AGN-driven. The outflow rate estimated in the CND, dM/dt=63(21,-37)M(sun)/yr, is an order of magnitude higher than the star formation rate at these radii, confirming that the outflow is AGN-driven. The power of the AGN is able to account for the estimated momentum and kinetic luminosity of the outflow. The CND mass load rate of the CND outflow implies a very short gas depletion time scale of 1 Myr.

  17. MODELING MOLECULAR HYPERFINE LINE EMISSION

    SciTech Connect

    Keto, Eric; Rybicki, George

    2010-06-20

    In this paper, we discuss two approximate methods previously suggested for modeling hyperfine spectral line emission for molecules whose collisional transition rates between hyperfine levels are unknown. Hyperfine structure is seen in the rotational spectra of many commonly observed molecules such as HCN, HNC, NH{sub 3}, N{sub 2}H{sup +}, and C{sup 17}O. The intensities of these spectral lines can be modeled by numerical techniques such as {Lambda}-iteration that alternately solve the equations of statistical equilibrium and the equation of radiative transfer. However, these calculations require knowledge of both the radiative and collisional rates for all transitions. For most commonly observed radio frequency spectral lines, only the net collisional rates between rotational levels are known. For such cases, two approximate methods have been suggested. The first method, hyperfine statistical equilibrium, distributes the hyperfine level populations according to their statistical weight, but allows the population of the rotational states to depart from local thermal equilibrium (LTE). The second method, the proportional method, approximates the collision rates between the hyperfine levels as fractions of the net rotational rates apportioned according to the statistical degeneracy of the final hyperfine levels. The second method is able to model non-LTE hyperfine emission. We compare simulations of N{sub 2}H{sup +} hyperfine lines made with approximate and more exact rates and find that satisfactory results are obtained.

  18. 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.

  19. The effect of expansion on high-energy emission from AGN jets

    NASA Astrophysics Data System (ADS)

    Pohl, Martin

    2006-04-01

    We study the radiation yield of relativistic particles in AGN jet that undergo expansion. For that purpose we use a specific model of particle acceleration (Pohl & Schlickeiser 2000) that is based on aborted relativistic shock acceleration and the direct conversion of bulk flow energy into particle energy. While jet expansion must be expected on account of the high pressure in the jet emission zones, the structure of radio galaxies suggests that the expansion is moderate. For various expansion profiles we solve the jet propagation equation and the continuity equations of energetic particles in parallel to derive observable signatures of expansion. A comparison with data suggests that expansion is very inefficient indeed, and we speculate on possible reasons why that is so. Though our study is based on a particular jet model, its results can -- within limits -- be extrapolated to other scenarios, provided they are based on jets being matter-dominated.

  20. 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.

  1. Evidence for ultra-fast outflows in radio-quiet AGNs. I. Detection and statistical incidence of Fe K-shell absorption lines

    NASA Astrophysics Data System (ADS)

    Tombesi, F.; Cappi, M.; Reeves, J. N.; Palumbo, G. G. C.; Yaqoob, T.; Braito, V.; Dadina, M.

    2010-10-01

    Context. Blue-shifted Fe K absorption lines have been detected in recent years between 7 and 10 keV in the X-ray spectra of several radio-quiet AGNs. The derived blue-shifted velocities of the lines can often reach mildly relativistic values, up to 0.2-0.4c. These findings are important because they suggest the presence of a previously unknown massive and highly ionized absorbing material outflowing from their nuclei, possibly connected with accretion disk winds/outflows. Aims: The scope of the present work is to statistically quantify the parameters and incidence of the blue-shifted Fe K absorption lines through a uniform analysis on a large sample of radio-quiet AGNs. This allows us to assess their global detection significance and to overcome any possible publication bias. Methods: We performed a blind search for narrow absorption features at energies greater than 6.4 keV in a sample of 42 radio-quiet AGNs observed with XMM-Newton. A simple uniform model composed by an absorbed power-law plus Gaussian emission and absorption lines provided a good fit for all the data sets. We derived the absorption lines parameters and calculated their detailed detection significance making use of the classical F-test and extensive Monte Carlo simulations. Results: We detect 36 narrow absorption lines on a total of 101 XMM-Newton EPIC pn observations. The number of absorption lines at rest-frame energies higher than 7 keV is 22. Their global probability to be generated by random fluctuations is very low, less than 3 × 10-8, and their detection have been independently confirmed by a spectral analysis of the MOS data, with associated random probability <10-7. We identify the lines as Fe XXV and Fe XXVI K-shell resonant absorption. They are systematically blue-shifted, with a velocity distribution ranging from zero up to ~0.3c, with a peak and mean value at ~0.1c. We detect variability of the lines on both EWs and blue-shifted velocities among different XMM-Newton observations

  2. Spectral classification indicators of emission-line galaxies from the Sloan Digital Sky Survey

    NASA Astrophysics Data System (ADS)

    Shi, Fei; Liu, Yu-Yan; Li, Pei-Yu; Yu, Ming; Lei, Yu-Ming; Wang, Jian

    2015-07-01

    To find efficient spectral classification diagrams to classify emission-line galaxies, especially in large surveys and huge data bases, an artificial neural network (ANN) supervised learning algorithms is applied to a sample of emission-line galaxies from the Sloan Digital Sky Survey data release 9 provided by the Max Planck Institute and the Johns Hopkins University (MPA/JHU) (http://www.sdss3.org/dr9/spectro/spectroaccess.php). A two-step approach is adopted. (i) The ANN network must be trained with a subset of objects that are known to be active galactic nuclei (AGNs) hosts, composites or star-forming galaxies, treating the strong emission-line flux measurements as input feature vectors in n-dimensional space, where n is the number of strong emission-line flux ratios. (ii) After the network is trained on a sample of galaxies, the remaining galaxies are classified in the automatic test analysis as AGN hosts, composites or star-forming galaxies. We show that the classification diagrams based on the [N II]/Hα versus other emission-line ratio, such as [O III]/Hβ, [Ne III]/[O II], ([O III]λ4959 + [O III]λ5007)/[O III]λ4363, [O II]/Hβ, [Ar III]/[O III], [S II]/Hα, and [O I]/Hα, plus colour, allows us to separate unambiguously AGN hosts, composites or star-forming galaxies. Among them, the diagram of [N II]/Hα versus [O III]/Hβ achieved an accuracy of 98 per cent for classification of AGN hosts, composites or star-forming galaxies. The other diagrams above except the diagram of [N II]/Hα versus [O III]/Hβ give an accuracy of ˜90 per cent. The code in the paper is available on the web (http://fshi5388.blog.163.com).

  3. Unveiling the X-ray/UV properties of AGN winds using Broad and mini-Broad Absorption Line Quasars

    NASA Astrophysics Data System (ADS)

    Giustini, M.

    2015-07-01

    BAL/mini-BALs are observed in the UV spectra of ˜ 20-30% of optically selected AGN as broad absorption troughs blueshifted by several thousands km/s, indicative of powerful nuclear winds. They could be representative of the average AGN if their winds cover only 20-30% of the continuum source, and/or represent an evolutionary state analogous to the high-soft state of BHB, when the jet emission is quenched and strong X-ray absorbing equatorial disk winds are virtually ubiquitous. High-quality, possibly time-resolved X-ray/UV studies are crucial to assess the global amount and 'character' of absorption in BAL/mini-BAL QSOs and to constrain the physical mechanism responsible for the launch and acceleration of their winds, therefore placing them in the broader context of AGN geometry and evolution. I will review here the known X-ray properties of BAL/mini-BAL QSOs, and present new results from a comprehensive X-ray spectral analysis of all the Palomar-Green BAL/mini-BAL QSOs with available XMM-Newton observations, for a total of 51 pointings of 14 different sources. These will include the most recent results from a high-quality simultaneous XMM/HST observational campaign on the mini-BAL QSO PG 1126-041, that unveiled with stunning details the X-ray/UV connection in action in an AGN disk wind through correlated X-ray/UV absorption variability.

  4. Theoretical modelling of the AGN iron line vs. continuum time-lags in the lamp-post geometry

    NASA Astrophysics Data System (ADS)

    Epitropakis, A.; Papadakis, I. E.; Dovčiak, M.; Pecháček, T.; Emmanoulopoulos, D.; Karas, V.; McHardy, I. M.

    2016-10-01

    Context. Theoretical modelling of time-lags between variations in the Fe Kα emission and the X-ray continuum might shed light on the physics and geometry of the X-ray emitting region in active galaxies (AGN) and X-ray binaries. We here present the results from a systematic analysis of time-lags between variations in two energy bands (5-7 vs. 2-4 keV) for seven X-ray bright and variable AGN. Aims: We estimate time-lags as accurately as possible and fit them with theoretical models in the context of the lamp-post geometry. We also constrain the geometry of the X-ray emitting region in AGN. Methods: We used all available archival XMM-Newton data for the sources in our sample and extracted light curves in the 5-7 and 2-4 keV energy bands. We used these light curves and applied a thoroughly tested (through extensive numerical simulations) recipe to estimate time-lags that have minimal bias, approximately follow a Gaussian distribution, and have known errors. Using traditional χ2 minimisation techniques, we then fitted the observed time-lags with two different models: a phenomenological model where the time-lags have a power-law dependence on frequency, and a physical model, using the reverberation time-lags expected in the lamp-post geometry. The latter were computed assuming a point-like primary X-ray source above a black hole surrounded by a neutral and prograde accretion disc with solar iron abundance. We took all relativistic effects into account for various X-ray source heights, inclination angles, and black hole spin values. Results: Given the available data, time-lags between the two energy bands can only be reliably measured at frequencies between ~5 × 10-5 Hz and ~10-3 Hz. The power-law and reverberation time-lag models can both fit the data well in terms of formal statistical characteristics. When fitting the observed time-lags to the lamp-post reverberation scenario, we can only constrain the height of the X-ray source. The data require, or are consistent

  5. THE ROLE OF FAST MAGNETIC RECONNECTION ON THE RADIO AND GAMMA-RAY EMISSION FROM THE NUCLEAR REGIONS OF MICROQUASARS AND LOW LUMINOSITY AGNs

    SciTech Connect

    Kadowaki, L. H. S.; Pino, E. M. de Gouveia Dal; Singh, C. B. E-mail: dalpino@iag.usp.br

    2015-04-01

    Fast magnetic reconnection events can be a very powerful mechanism operating in the core region of microquasars and active galactic nuclei (AGNs). In earlier work, it has been suggested that the power released by fast reconnection events between the magnetic field lines lifting from the inner accretion disk region and the lines anchored into the central black hole could accelerate relativistic particles and produce the observed radio emission from microquasars and low luminosity AGNs (LLAGNs). Moreover, it has been proposed that the observed correlation between the radio emission and the mass of these sources, spanning 10{sup 10} orders of magnitude in mass, might be related to this process. In the present work, we revisit this model comparing two different fast magnetic reconnection mechanisms, namely, fast reconnection driven by anomalous resistivity (AR) and by turbulence. We apply the scenario above to a much larger sample of sources (including also blazars, and gamma-ray bursts—GRBs), and find that LLAGNs and microquasars do confirm the trend above. Furthermore, when driven by turbulence, not only their radio but also their gamma-ray emission can be due to magnetic power released by fast reconnection, which may accelerate particles to relativistic velocities in the core region of these sources. Thus the turbulent-driven fast reconnection model is able to reproduce verywell the observed emission. On the other hand, the emission from blazars and GRBs does not follow the same trend as that of the LLAGNs and microquasars, indicating that the radio and gamma-ray emission in these cases is produced beyond the core, along the jet, by another population of relativistic particles, as expected.

  6. The Nature of Active Galactic Nuclei with Velocity Offset Emission Lines

    NASA Astrophysics Data System (ADS)

    Müller-Sánchez, F.; Comerford, J.; Stern, D.; Harrison, F. A.

    2016-10-01

    We obtained Keck/OSIRIS near-IR adaptive optics-assisted integral-field spectroscopy to probe the morphology and kinematics of the ionized gas in four velocity-offset active galactic nuclei (AGNs) from the Sloan Digital Sky Survey. These objects possess optical emission lines that are offset in velocity from systemic as measured from stellar absorption features. At a resolution of ∼0.″18, OSIRIS allows us to distinguish which velocity offset emission lines are produced by the motion of an AGN in a dual supermassive black hole system, and which are produced by outflows or other kinematic structures. In three galaxies, J1018+2941, J1055+1520, and J1346+5228, the spectral offset of the emission lines is caused by AGN-driven outflows. In the remaining galaxy, J1117+6140, a counterrotating nuclear disk is observed that contains the peak of Paα emission 0.″2 from the center of the galaxy. The most plausible explanation for the origin of this spatially and kinematically offset peak is that it is a region of enhanced Paα emission located at the intersection zone between the nuclear disk and the bar of the galaxy. In all four objects, the peak of ionized gas emission is not spatially coincident with the center of the galaxy as traced by the peak of the near-IR continuum emission. The peaks of ionized gas emission are spatially offset from the galaxy centers by 0.″1–0.″4 (0.1–0.7 kpc). We find that the velocity offset originates at the location of this peak of emission, and the value of the offset can be directly measured in the velocity maps. The emission-line ratios of these four velocity-offset AGNs can be reproduced only with a mixture of shocks and AGN photoionization. Shocks provide a natural explanation for the origin of the spatially and spectrally offset peaks of ionized gas emission in these galaxies. Based on observations at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the

  7. Galaxy emission line classification using three-dimensional line ratio diagrams

    SciTech Connect

    Vogt, Frédéric P. A.; Dopita, Michael A.; Kewley, Lisa J.; Sutherland, Ralph S.; Scharwächter, Julia; Basurah, Hassan M.; Ali, Alaa; Amer, Morsi A.

    2014-10-01

    Two-dimensional (2D) line ratio diagnostic diagrams have become a key tool in understanding the excitation mechanisms of galaxies. The curves used to separate the different regions—H II-like or excited by an active galactic nucleus (AGN)—have been refined over time but the core technique has not evolved significantly. However, the classification of galaxies based on their emission line ratios really is a multi-dimensional problem. Here we exploit recent software developments to explore the potential of three-dimensional (3D) line ratio diagnostic diagrams. We introduce the ZQE diagrams, which are a specific set of 3D diagrams that separate the oxygen abundance and the ionization parameter of H II region-like spectra and also enable us to probe the excitation mechanism of the gas. By examining these new 3D spaces interactively, we define the ZE diagnostics, a new set of 2D diagnostics that can provide the metallicity of objects excited by hot young stars and that cleanly separate H II region-like objects from the different classes of AGNs. We show that these ZE diagnostics are consistent with the key log [N II]/Hα versus log [O III]/Hβ diagnostic currently used by the community. They also have the advantage of attaching a probability that a given object belongs to one class or the other. Finally, we discuss briefly why ZQE diagrams can provide a new way to differentiate and study the different classes of AGNs in anticipation of a dedicated follow-up study.

  8. Multiwavelength Observations of AGN Jets: Untangling the Coupled Problems of Emission Mechanism and Jet Structure

    NASA Astrophysics Data System (ADS)

    Perlman, Eric S.; Avachat, Sayali S.; Clautice, Devon; Georganopoulos, Markos; Meyer, Eileen; Cara, Mihai

    2016-04-01

    The discovery of X-ray and optical emission from large numbers of AGN jets is one of the key legacies of the Chandra X-ray Observatory and Hubble Space Telescope. Several dozen optical and X-ray emitting jets are now known, most of which are seen in both bands as well as in the radio, where they were first discovered. Jets carry prodigious amounts of energy and mass out from the nuclear regions out to tens to hundreds of kiloparsecs distant from the central black hole, depositing it into the host galaxy and cluster. Interpreting their multiwavelength emissions has not been easy: while in most jets, the optical and radio emission in many objects is believed to emerge via the synchrotron process, due to its characteristic spectral shape and high radio polarization, the X-ray emission has been a tougher nut to crack. In less powerful, FR I jets, such as M87, the X-ray emission is believed to be synchrotron emission from the highest energy electrons, requiring in situ particle acceleration due to the short radiative lifetimes of the particles. However, in FR II and quasar jets, a variety of emission mechanisms are possible. Until the last few years, the leading interpretation had been inverse-Comptonization of Cosmic Microwave Background photons (the IC/CMB mechanism). This requires the jet to be relativistic out to hundreds of kiloparsecs from the nucleus, and requires an electron spectrum that extends to very low Lorentz factors. However, that now appears less likely, due to observed high optical polarizations in jets where the optical and X-ray emission appears to lie on the same spectral component, as well as limits derived from Fermi observations in the GeV gamma-rays. It now appears more likely that the X-rays must arise as synchrotron emission from a second, high energy electron population. With this revelation, we must tackle anew the coupling between jet structure and emission mechanisms. Multiwavelength imaging and polarimetry can give us clues to the

  9. THE LICK AGN MONITORING PROJECT: ALTERNATE ROUTES TO A BROAD-LINE REGION RADIUS

    SciTech Connect

    Greene, Jenny E.; Hood, Carol E.; Barth, Aaron J.; Bentz, Misty C.; Walsh, Jonelle L.; Bennert, Vardha N.; Treu, Tommaso; Filippenko, Alexei V.; Gates, Elinor; Malkan, Matthew A.; Woo, Jong-Hak

    2010-11-01

    It is now possible to estimate black hole (BH) masses across cosmic time, using broad emission lines in active galaxies. This technique informs our views of how galaxies and their central BHs coevolve. Unfortunately, there are many outstanding uncertainties associated with these 'virial' mass estimates. One of these comes from using the accretion luminosity to infer a size for the broad-line region (BLR). Incorporating the new sample of low-luminosity active galaxies from our recent monitoring campaign at Lick Observatory, we recalibrate the radius-luminosity relation with tracers of the accretion luminosity other than the optical continuum. We find that the radius of the BLR scales as the square root of the X-ray and H{beta} luminosities, in agreement with recent optical studies. On the other hand, the scaling appears to be marginally steeper with narrow-line luminosities. This is consistent with a previously observed decrease in the ratio of narrow-line to X-ray luminosity with increasing total luminosity. The radius of the BLR correlates most tightly with H{beta} luminosity, while the X-ray and narrow-line relations both have comparable scatter of a factor of 2. These correlations provide useful alternative virial BH masses in objects with no detectable optical/UV continuum emission, such as high-redshift galaxies with broad emission lines, radio-loud objects, or local active galaxies with galaxy-dominated continua.

  10. Constraining UV continuum slopes of active galactic nuclei with cloudy models of broad-line region extreme-ultraviolet emission lines

    SciTech Connect

    Moloney, Joshua; Michael Shull, J. E-mail: michael.shull@colorado.edu

    2014-10-01

    Understanding the composition and structure of the broad-line region (BLR) of active galactic nuclei (AGNs) is important for answering many outstanding questions in supermassive black hole evolution, galaxy evolution, and ionization of the intergalactic medium. We used single-epoch UV spectra from the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope to measure EUV emission-line fluxes from four individual AGNs with 0.49 ≤ z ≤ 0.64, two AGNs with 0.32 ≤ z ≤ 0.40, and a composite of 159 AGNs. With the CLOUDY photoionization code, we calculated emission-line fluxes from BLR clouds with a range of density, hydrogen ionizing flux, and incident continuum spectral indices. The photoionization grids were fit to the observations using single-component and locally optimally emitting cloud (LOC) models. The LOC models provide good fits to the measured fluxes, while the single-component models do not. The UV spectral indices preferred by our LOC models are consistent with those measured from COS spectra. EUV emission lines such as N IV λ765, O II λ833, and O III λ834 originate primarily from gas with electron temperatures between 37,000 K and 55,000 K. This gas is found in BLR clouds with high hydrogen densities (n {sub H} ≥ 10{sup 12} cm{sup –3}) and hydrogen ionizing photon fluxes (Φ{sub H} ≥ 10{sup 22} cm{sup –2} s{sup –1}).

  11. AGN flickering on 10-100 kyr timescales

    NASA Astrophysics Data System (ADS)

    Sartori, Lia F.; Schawinski, Kevin; Kill, Bill; Maksym, Peter; Koss, Michael; Argo, Megan; Urry, Meg; Wong, Ivy; Lintott, Chris

    2016-08-01

    The study of AGN variability on timescales of 10^4-10^5 years is important in order to understand the BH - host galaxy interaction and coevolution. The discovery of "Hanny's Voorwerp" (HV), an extended emission line region associated with the nearby galaxy IC 2497, provided us with a laboratory to study AGN variability over such timescales. HV was illuminated by a strong quasar in IC 2497, but this quasar significantly shut down in the last 200 kyrs. Thanks to its recent shutdown we can now explore the host galaxy unimpeded by the presence of a quasar dominating the observations, while the Voorwerp preserves the echoes of its past activity. Recent studies on the optical properties of hard X-ray selected AGN suggest that AGN may flicker on and off hundreds or thousands times with each burst lasting ~10^5 yrs. Systems similar to IC 2497 and HV, the so-called Voorwerpjes, allow us to constrain the last stages of the AGN lifecycle. On the other hand, we recently suggested that the switch on phase may be observed in the so-called optically elusive AGN. In this talk I will review both observational evidence and results from simulation work which support this picture, and explain how optically elusive AGN and Voorwerpjes galaxies can help us to understand different phases of the AGN lifecycle. Moreover, I will discuss possible implications for AGN feedback, BH - host galaxy coevolution, and the analogy between AGN and X-ray binaries accretion physics.

  12. The mid-infrared emission of narrow-line active galactic nuclei: Star formation, nuclear activity, and two populations revealed by WISE

    SciTech Connect

    Rosario, David J.; Burtscher, Leonard; Davies, Richard; Genzel, Reinhard; Lutz, Dieter; Tacconi, Linda J.

    2013-12-01

    We explore the nature of the long-wavelength mid-infrared (MIR) emission of a sample of 13,000 local Type II (narrow-line) active galactic nuclei (AGNs) from the Sloan Digital Sky Survey (SDSS) using 12 μm and 22 μm photometry from the WISE all-sky survey. In combination with FIRST 1.4 GHz photometry, we show that AGNs divide into two relatively distinct populations or 'branches' in the plane of MIR and radio luminosity. Seyfert galaxies lie almost exclusively on an MIR-bright branch (Branch A), while low-ionization nuclear emission line galaxies (LINERs) are split evenly into Branch A and the MIR-faint Branch B. We devise various tests to constrain the processes that define the branches, including a comparison to the properties of pure star-forming inactive galaxies on the MIR-radio plane. We demonstrate that the total MIR emission of objects on Branch A, including most Seyfert galaxies, is governed primarily by host star formation, with ≈15% of the 22 μm luminosity coming from AGN-heated dust. This implies that ongoing dusty star formation is a general property of Seyfert host galaxies. We show that the 12 μm broadband luminosity of AGNs on Branch A is suppressed with respect to star-forming galaxies, possibly due to the destruction of PAHs or deeper 10 μm Si absorption in AGNs. We uncover a correlation between the MIR luminosity and [O III] λ5007 luminosity in AGNs. This suggests a relationship between the star formation rate and nuclear luminosity in the AGN population, but we caution on the importance of selection effects inherent to such AGN-dominated emission-line galaxies in driving such a correlation. We highlight the MIR-radio plane as a useful tool in comparative studies of star formation and nuclear activity in AGNs.

  13. Multi-faceted AGN

    NASA Astrophysics Data System (ADS)

    Farrar, Glennys R.; Chen, Yanping; Dai, Yuxiao; Zaw, Ingyin

    2016-08-01

    An interesting question is how frequently an object is an AGN by multiple different criteria — e.g., is simultaneously a narrow-line optical AGN and an X-ray or radio AGN, possibly as a function of luminosities in the various wavebands and perhaps host galaxy type. Answering such questions quantitatively has been difficult up to now because of the lack of a complete, uniformly selected optical AGN catalog. Here we report first results of such an analysis, using the new, all-sky catalog of uniformly selected optical AGNs from Zaw, Chen and Farrar (2016), the Swift-BAT 70-month catalog of X-ray AGN (Baumgartner et al., 2013), and the van Velzen et al. (2012) catalog of radio AGN.

  14. VizieR Online Data Catalog: AGN data and absorption-line measurements (Richter+, 2016)

    NASA Astrophysics Data System (ADS)

    Richter, P.; Wakker, B. P.; Fechner, C.; Herenz, P.; Tepper-Garcia, T.; Fox, A. J.

    2016-03-01

    Names, positions and emission redshifts for 303 QSOs are provided in Table A.1. Table A.2 summarizes the absorption-line measurements for 59 intervening SiIII absorbers including absorption redshifts, equivalent-widths, and column densities for various different ions. (2 data files).

  15. Cloudy 94 and Applications to Quasar Emission Line Regions

    NASA Technical Reports Server (NTRS)

    Ferland, Gary J.

    2000-01-01

    This review discusses the most recent developments of the plasma simulation code Cloudy and its application to the, emission-line regions of quasars. The longterm goal is to develop the tools needed to determine the chemical composition of the emitting gas and the luminosity of the central engine for any emission line source. Emission lines and the underlying thermal continuum are formed in plasmas that are far from thermodynamic equilibrium. Their thermal and ionization states are the result of a balance of a vast set of microphysical processes. Once produced, radiation must, propagate out of the (usually) optically thick source. No analytic solutions are possible, and recourse to numerical simulations is necessary. I am developing the large-scale plasma simulation code Cloudy as an investigative tool for this work, much as an observer might build a spectrometer. This review describes the current version of Cloudy, version 94. It describes improvements made since the, release of the previous version, C90. The major recent, application has been the development of the "Locally Optimally-Emitting Cloud" (LOC) model of AGN emission line regions. Powerful selection effects, introduced by the atomic physics and line formation process, permit individual lines to form most efficiently only near certain selected parameters. These selection effects, together with the presence of gas with a wide range of conditions, are enough to reproduce the spectrum of a typical quasar with little dependence on details. The spectrum actually carries little information to the identity of the emitters. I view this as a major step forward since it provides a method to handle accidental details at the source, so that we can concentrate on essential information such as the luminosity or chemical composition of the quasar.

  16. Extended X-ray emission in the IC 2497 - Hanny's Voorwerp system: energy injection in the gas around a fading AGN

    NASA Astrophysics Data System (ADS)

    Sartori, Lia F.; Schawinski, Kevin; Koss, Michael; Treister, Ezequiel; Maksym, W. Peter; Keel, William C.; Urry, C. Megan; Lintott, Chris J.; Wong, O. Ivy

    2016-04-01

    We present deep Chandra X-ray observations of the core of IC 2497, the galaxy associated with Hanny's Voorwerp and hosting a fading AGN. We find extended soft X-ray emission from hot gas around the low intrinsic luminosity (unobscured) AGN (Lbol ˜ 1042-1044 erg s-1). The temperature structure in the hot gas suggests the presence of a bubble or cavity around the fading AGN ({{E}}_bub ˜ 10^{54}{-}10^{55} erg). A possible scenario is that this bubble is inflated by the fading AGN, which after changing accretion state is now in a kinetic mode. Other possibilities are that the bubble has been inflated by the past luminous quasar (Lbol ˜ 1046 erg s-1), or that the temperature gradient is an indication of a shock front from a superwind driven by the AGN. We discuss the possible scenarios and the implications for the AGN-host galaxy interaction, as well as an analogy between AGN and X-ray binaries lifecycles. We conclude that the AGN could inject mechanical energy into the host galaxy at the end of its lifecycle, and thus provide a source for mechanical feedback, in a similar way as observed for X-ray binaries.

  17. The predominance of dust in the polar region of AGN

    NASA Astrophysics Data System (ADS)

    Asmus, Daniel; Hönig, Sebastian; Gandhi, Poshak

    2016-08-01

    Recent mid-infrared (MIR) interferometric observations showed in few AGN that the bulk of the infrared emission originates from the polar region above the putative torus, where only little dust should be present. Our investigation of 149 Seyferts with high angular resolution MIR images from, e.g., VLT/VISIR shows that significant polar dust emission is probably very common in AGN. The relative amount of resolved MIR emission is at least 40 per cent and scales with the narrow emission line fluxes implying a strong connection between the extended continuum and line emitters. These results together with the radio-quiet nature of the Seyferts support the scenario that the bulk of MIR emission is emitted by dust in the polar region and not by the torus, which would demand a new paradigm for the infrared emission structure in AGN. We will discuss some of the resulting implications and give prospects for future instruments to further test this scenario.

  18. Possible evidence of destroying small PAH particles by radiation from AGNs

    NASA Astrophysics Data System (ADS)

    Feng, Qi-Chen; Wang, Jing; Wei, Jian-Yan

    2015-02-01

    The issue of destroying small polycyclic aromatic hydrocarbon (PAH) particles by radiation from AGNs is examined through optical narrow-emission line ratios of a sample of type II AGNs. We find that narrow-line ratios [OI]λ6300/Hα and [SII]λ6716, λ6731/Hα have prominent correlations with the PAH 11.3/7.7 ratio in our selected sample of AGNs. Because of the marginal (and in some cases no) dependence of the PAH ratio on the gas metallicity, a possible explanation for the correlations is the destruction of small PAH particles by the hard ionizing field associated with the AGNs.

  19. 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.

  20. X-ray long-term variations in the low-luminosity AGN NGC 835 and its circumnuclear emission

    NASA Astrophysics Data System (ADS)

    González-Martín, O.; Hernández-García, L.; Masegosa, J.; Márquez, I.; Rodríguez-Espinosa, J. M.; Acosta-Pulido, J. A.; Alonso-Herrero, A.; Dultzin, D.; Esparza Arredondo, D.

    2016-03-01

    Context. Obscured active galactic nuclei (AGNs) are thought to be very common in the Universe. Observations and surveys have shown that the number of sources increases for near galaxies and at the low-luminosity regime (the so-called LLAGNs). Furthermore, many AGNs show changes in their obscuration properties at X-rays that may suggest a configuration of clouds very close to the accretion disk. However, these variations could also be due to changes in the intrinsic continuum of the source. It is therefore important to study nearby AGN to better understand the locus and distribution of clouds in the neighbourhood of the nucleus. Aims: We aim to study the nuclear obscuration of LLAGN NGC 835 and its extended emission using mid-infrared observations. Methods: We present sub-arcsecond-resolution mid-infrared 11.5 μm imaging of the LLAGN galaxy NGC 835 obtained with the instrument CanariCam in the Gran Telescopio CANARIAS (GTC), archival Spitzer/IRS spectroscopy, and archival Chandra data observed in 2000, 2008, and 2013. Results: The GTC/CanariCam 11.5 μm image reveals faint extended emission out to ~6 arcsec. We obtained a nuclear flux of F(11.5 μm) ~ 18 mJy, whereas the extended emission accounts for 90% of the total flux within the 6 arcsec. This means that the low angular resolution (~4 arcsec) IRS spectrum is dominated by this extended emission and not by the AGN. This is clearly seen in the Spitzer/IRS spectrum, which resembles that of star-forming galaxies. Although the extended soft X-ray emission shows some resemblance with that of the mid-infrared, the knots seen at X-rays are mostly located in the inner side of this mid-infrared emission. The nuclear X-ray spectrum of the source has undergone a spectral change between 2000/2008 and 2013. We argue that this variation is most probably due to changes in the hydrogen column density from ~8 × 1023 cm-2 to ~3 × 1023 cm-2. NGC 835 therefore is one of the few LLAGN, together with NGC 1052, in which changes in

  1. 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.

  2. 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.

  3. 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.

  4. The Of emission lines near 4650 A

    NASA Astrophysics Data System (ADS)

    Underhill, A. B.; Gilroy, K. K.; Hill, G. M.

    1989-09-01

    Rectified, normalized, high S/N intensity tracings of nine Of stars were obtained from Reticon spectra in the 4550-4800-A region. The well-known relatively sharp Of emission lines are seen to stand on pedestals of broad weak emission somewhat like the broad emission lines from WR stars. It is suggested that cascades following dielectronic recombination may be an important process driving some lines of N III, C III, and C IV into the emission of Of stars, and that the sharp Of lines come from plasma that is stationary with respect to the star. The broad emission features show an extensive low-density wind from each star. The results imply that the detection of two, more or less equal, broad jumps in the rest spectra of galaxies at about 4640 and 4686 A is more indicative of Of stars than of WR stars.

  5. Radio continuum and X-ray emission from the most extreme far-IR-excess galaxy NGC 1377. An extremely obscured AGN revealed

    NASA Astrophysics Data System (ADS)

    Costagliola, F.; Herrero-Illana, R.; Lohfink, A.; Pérez-Torres, M.; Aalto, S.; Muller, S.; Alberdi, A.

    2016-10-01

    Context. Galaxies which strongly deviate from the radio-far infrared (FIR) correlation are of great importance for studies of galaxy evolution as they may be tracing early, short-lived stages of starbursts and active galactic nuclei (AGNs). The most extreme FIR-excess galaxy NGC 1377 has long been interpreted as a young dusty starburst, but millimeter observations of CO lines revealed a powerful collimated molecular outflow which cannot be explained by star formation alone. Aims: This paper aims to determine the nature of the energy source in the nucleus of NGC 1377 and to study the driving mechanism of the collimated CO outflow. Methods: We present new radio observations of NGC 1377 at 1.5 and 10 GHz obtained with the Jansky Very Large Array (JVLA) and Chandra X-ray observations. The observations are compared to synthetic starburst models to constrain the properties of the central energy source. Results: We obtained the first detection of the cm radio continuum and X-ray emission in NGC 1377. We found that the radio emission is distributed in two components, one on the nucleus and another offset by 4.5 arcsec to the south-west. We confirm the extreme FIR-excess of the galaxy, with a qFIR ≃ 4.2, which deviates by more than 7σ from the radio-FIR correlation. Soft X-ray emission is detected on the off-nucleus component. From the radio emission we estimated for a young (<10 Myr) starburst a star formation rate (SFR) of <0.1 M⊙ yr-1. Such a SFR is not sufficient to power the observed IR luminosity and to drive the CO outflow. Conclusions: We found that a young starburst cannot reproduce all the observed properties of the nucleus of NGC 1377. We suggest that the galaxy may be harboring a radio-quiet, obscured AGN of 106M⊙, accreting at near-Eddington rates. We speculate that the off-nucleus component may be tracing an hot-spot in the AGN jet.

  6. 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}.

  7. 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.

  8. Observations of emission lines in M supergiants

    NASA Technical Reports Server (NTRS)

    Lambert, D. L.

    1979-01-01

    Copernicus observations of Mg 2 h and k emission lines from M giants and supergiants are described. Supergiants with extensive circumstellar gas shells show an asymmetric k line. The asymmetry is ascribed to superimposed lines of Fe 1 and Mn 1. The Mg 2 line width fit the Wilson-Bappu relation derived from observations of G and K Stars. Results of correlated ground-based observations include (1) the discovery of K 1 fluorescent emission from the Betelgeuse shell; (2) extimates of the mass-loss rates; and (3) the proposal that silicate dust grains must account for the major fraction of the Si atoms in the Betelgeuse shell.

  9. 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.

  10. 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.

  11. 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.

  12. Exploring AGN-starburst coexistence in galaxies at z ˜ 0.8 using the [O III]4959+5007/[O III]4363 line ratio

    NASA Astrophysics Data System (ADS)

    Contini, M.

    2016-09-01

    Using detailed modelling, we analyse the spectra observed from the sample galaxies at z ˜ 0.8 presented by Ly et al., constraining the models by the [O III]5007+4959/[O III]4363 line ratios. Composite models (shock + photoionization) are adopted. Shock velocities ≥100 km s-1 and pre-shock densities n0 ˜ 200 cm-3 characterize the gas surrounding the starburst (SB), while n0 are higher by a factor of 1.5-10 in the AGN emitting gas. SB effective temperatures are similar to those of quiescent galaxies (T* ˜ 4-7 × 104 K). Cloud geometrical thicknesses in the SB are ≤1016 cm, indicating major fragmentation, while in AGN they reach >10 pc. O/H are about solar for all the objects, except for a few AGN clouds with O/H = 0.3-0.5 solar. SB models reproduce most of the data within the observational errors. About half of the objects' spectra are well fitted by an accreting AGN. Some galaxies show multiple radiation sources, such as SB + AGN, or a double AGN.

  13. Infrared coronal emission lines and the possibility of their maser emission in Seyfert nuclei

    NASA Technical Reports Server (NTRS)

    Greenhouse, Matthew A.; Feldman, Uri; Smith, Howard A.; Klapisch, Marcel; Bhatia, Anand K.; Bar-Shalom, Abi

    1993-01-01

    Energetic emitting regions have traditionally been studied via x-ray, UV and optical emission lines of highly ionized intermediate mass elements. Such lines are often referred to as 'coronal lines' since the ions, when produced by collisional ionization, reach maximum abundance at electron temperatures of approx. 10(exp 5) - 10(exp 6) K typical of the sun's upper atmosphere. However, optical and UV coronal lines are also observed in a wide variety of Galactic and extragalactic sources including the Galactic interstellar medium, nova shells, supernova remnants, galaxies and QSOs. Infrared coronal lines are providing a new window for observation of energetic emitting regions in heavily dust obscured sources such as infrared bright merging galaxies and Seyfert nuclei and new opportunities for model constraints on physical conditions in these sources. Unlike their UV and optical counterparts, infrared coronal lines can be primary coolants of collisionally ionized plasmas with 10(exp 4) less than T(sub e)(K) less than 10(exp 6) which produce little or no optical or shorter wavelength coronal line emission. In addition, they provide a means to probe heavily dust obscured emitting regions which are often inaccessible to optical or UV line studies. In this poster, we provide results from new model calculations to support upcoming Infrared Space Observatory (ISO) and current ground-based observing programs involving infrared coronal emission lines in AGN. We present a complete list of infrared (lambda greater than 1 micron) lines due to transitions within the ground configurations 2s(2)2p(k) and 3s(2)3p(k) (k = 1 to 5) or the first excited configurations 2s2p and 3s3p of highly ionized (x greater than or equal to 100 eV) astrophysically abundant (n(X)/n(H) greater than or equal to 10(exp -6)) elements. Included are approximately 74 lines in ions of O, Ne, Na, Mg, Al, Si, S, Ar, Ca, Fe, and Ni spanning a wavelength range of approximately 1 - 280 microns. We present new

  14. DOUBLE-PEAKED NARROW EMISSION-LINE GALAXIES FROM THE SLOAN DIGITAL SKY SURVEY. I. SAMPLE AND BASIC PROPERTIES

    SciTech Connect

    Ge Junqiang; Hu Chen; Wang Jianmin; Zhang Shu; Bai Jinming

    2012-08-01

    Recently, much attention has been paid to double-peaked narrow emission-line (NEL) galaxies, some of which are suggested to be related to merging galaxies. We make a systematic search to build the largest sample of these sources from Data Release 7 of the Sloan Digital Sky Survey (SDSS). With reasonable criteria for fluxes, FWHMs of the emission lines, and separations of the peaks, we select 3030 double-peaked NEL galaxies. In light of the existence of broad Balmer lines and the locations of the two components of double-peaked NELs distinguished by the Kauffmann et al. criteria in the Baldwin-Phillips-Terlevich diagram, we find that there are 81 Type I active galactic nuclei (AGNs), 837 double Type II AGNs (2-Type II), 708 galaxies with double star-forming components (2-SF), 400 with mixed star-forming and Type II AGN components (Type II + SF), and 1004 unknown-type objects. As a by-product, a sample of galaxies (12,582) with asymmetric or top-flat profiles of emission lines is established. After visually inspecting the SDSS images of the two samples, we find 54 galaxies with dual cores. The present samples can be used to study the dynamics of merging galaxies, the triggering mechanism of black hole activity, the hierarchical growth of galaxies, and the dynamics of narrow line regions driven by outflows and a rotating disk.

  15. Mini-Survey on SDSS OIII AGN with Swift

    NASA Technical Reports Server (NTRS)

    Angelini, Lorella

    2008-01-01

    The number of AGN and their luminosity distribution are crucial parameters for our understanding of the AGN phenomenon. There is a common wisdom that every massive galaxy has a massive black hole. However, most of these objects either are not radiating or until recently have been very difficult to detect. The Sloan Digital Sky Survey (SDSS) data, based on the [OIII] line indicate that perhaps up to 20% of all galaxies may be classified as AGN a surprising result that must be checked with independent data. X-ray surveys have revealed that hard X-ray selected AGN show a strong luminosity dependent evolution and their luminosity function (LF) shows a dramatic break towards low $L_X$ (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 {it optically-selected samples} shows no such break and no differences between narrow and broad-line objects. Assuming both hard X-ray and [O{\\sc iii}] emission are fair indicators of AGN activity, it is important to understand this discrepancy. We present here the results of a min-survey done with Swift on a selected sample of SDSS selected AGN. The objects have been sampled at different L([O{\\sc iii}]) to check the relation with the $L_X$ observed with Swift.

  16. Optical-to-X-ray emission in low-absorption AGN: results from the Swift-BAT 9-month catalogue

    NASA Astrophysics Data System (ADS)

    Vasudevan, R. V.; Mushotzky, R. F.; Winter, L. M.; Fabian, A. C.

    2009-11-01

    We present simultaneous optical-to-X-ray spectral energy distributions (SEDs) from Swift's X-ray and UV-optical telescopes (XRTs and UVOTs) for a well-selected sample of 26 low-redshift (z < 0.1) active galactic nuclei (AGN) from the Swift/Burst Alert Telescope 9-month catalogue, the largest well-studied, hard X-ray-selected survey of local AGN to date. Our sub-sample consists of AGN with low intrinsic X-ray absorption (NH < 1022cm-2) and minimal spectral complexity, to more accurately recover the intrinsic accretion luminosity in these sources. We perform a correction for host galaxy contamination in all available UVOT filter images to recover the intrinsic AGN emission and estimate intrinsic dust extinction from the resultant nuclear SEDs. Black hole mass estimates are determined from the host galaxy Two-Micron All-Sky Survey K-band bulge luminosity. Accretion rates determined from our SEDs are on average low (Eddington ratios λEdd <~ 0.1) and hard X-ray bolometric corrections cluster at ~10-20, in contrast with the higher values seen for quasars. An average SED for the 22 low accretion rate (λEdd < 0.1) objects is presented, with and without correction for extinction. Significant dust reddening is found in some objects despite the selection of low NH objects, emphasizing the complex relationship between these two types of absorption. We do not find a correlation of the optical-to-X-ray spectral index with the Eddington ratio, regardless of the optical reference wavelength chosen for defining the spectral index. An anticorrelation of bolometric correction with black hole mass may reinforce `cosmic downsizing' scenarios, since the higher bolometric corrections at low mass would boost accretion rates in local, lower mass black holes. We also perform a basic analysis of the UVOT-derived host galaxy colours for our sample and find hosts cluster near the `green valley' of the colour-magnitude diagram, but better quality images are needed for a more definitive

  17. A support vector machine for spectral classification of emission-line galaxies from the Sloan Digital Sky Survey

    NASA Astrophysics Data System (ADS)

    Shi, Fei; Liu, Yu-Yan; Sun, Guang-Lan; Li, Pei-Yu; Lei, Yu-Ming; Wang, Jian

    2015-10-01

    The emission-lines of galaxies originate from massive young stars or supermassive blackholes. As a result, spectral classification of emission-line galaxies into star-forming galaxies, active galactic nucleus (AGN) hosts, or compositions of both relates closely to formation and evolution of galaxy. To find efficient and automatic spectral classification method, especially in large surveys and huge data bases, a support vector machine (SVM) supervised learning algorithm is applied to a sample of emission-line galaxies from the Sloan Digital Sky Survey (SDSS) data release 9 (DR9) provided by the Max Planck Institute and the Johns Hopkins University (MPA/JHU). A two-step approach is adopted. (i) The SVM must be trained with a subset of objects that are known to be AGN hosts, composites or star-forming galaxies, treating the strong emission-line flux measurements as input feature vectors in an n-dimensional space, where n is the number of strong emission-line flux ratios. (ii) After training on a sample of emission-line galaxies, the remaining galaxies are automatically classified. In the classification process, we use a 10-fold cross-validation technique. We show that the classification diagrams based on the [N II]/Hα versus other emission-line ratio, such as [O III]/Hβ, [Ne III]/[O II], ([O III]λ4959+[O III]λ5007)/[O III]λ4363, [O II]/Hβ, [Ar III]/[O III], [S II]/Hα, and [O I]/Hα, plus colour, allows us to separate unambiguously AGN hosts, composites or star-forming galaxies. Among them, the diagram of [N II]/Hα versus [O III]/Hβ achieved an accuracy of 99 per cent to separate the three classes of objects. The other diagrams above give an accuracy of ˜91 per cent.

  18. AGN content of X-ray, IR and radio sources

    NASA Astrophysics Data System (ADS)

    Mickaelian, A. M.; Paronyan, G. M.; Abrahamyan, H. V.; Gyulzadyan, M. V.; Mikayelyan, G. A.

    2016-09-01

    We have carried out a number of surveys and identification works related to X-ray, IR and radio sources and searched for extragalactic ones. Among them, most interesting are Active Galactic Nuclei (AGN) and Starburst (SB) Galaxies. Some 4500 AGN have been revealed from ROSAT BSC and FSC sources, and many more are hidden ones; those showing evidence of activity but with no emission lines in optical wavelengths. We estimated AGN content of X-ray sources as 52.9%. IR sources contain thousands of SBs, and most important are those having signs of interaction and/or merging. We have carried out optical identifications of IRAS point sources, and 1278 IR galaxies have been revealed, including LIRGs and ULIRGs. We have also combined IRAS PSC and FSC catalogs and compiled its extragalactic sample, which allowed to estimate AGN content among IR sources as 23.7%. Extragalactic radio sources contain bright galaxies, AGN and SBs. We have studied the border between AGN and normal galaxies by radio/optical flux ratios to establish which objects may be attributed to AGN based on radio properties. Interestingly, absolute majority of objects associated with both X-ray and radio sources are AGN.

  19. Local Group Galaxy Emission-line Survey

    NASA Astrophysics Data System (ADS)

    Blaha, Cindy; Baildon, Taylor; Mehta, Shail; Garcia, Edgar; Massey, Philip; Hodge, Paul W.

    2015-01-01

    We present the results of the Local Group Galaxy Emission-line Survey of Hα emission regions in M31, M33 and seven dwarf galaxies in (NGC6822, IC10, WLM, Sextans A and B, Phoenix and Pegasus). Using data from the Local Group Galaxy Survey (LGGS - see Massey et al, 2006), we used continuum-subtracted Ha emission line images to define emission regions with a faint flux limit of 10 -17 ergs-sec-1-cm-2above the background. We have obtained photometric measurements for roughly 7450 Hα emission regions in M31, M33 and five of the seven dwarf galaxies (no regions for Phoenix or Pegasus). Using these regions, with boundaries defined by Hα-emission flux limits, we also measured fluxes for the continuum-subtracted [OIII] and [SII] images and constructed a catalog of Hα fluxes, region sizes and [OIII]/ Hα and [SII]/ Hα line ratios. The HII region luminosity functions and size distributions for the spiral galaxies M31 and M33 are compared with those of the dwarf galaxies NGC 6822 and IC10. For M31 and M33, the average [SII]/ Hα and [OIII]/ Hα line ratios, plotted as a function of galactocentric radius, display a linear trend with shallow slopes consistent with other studies of metallicity gradients in these galaxies. The galaxy-wide averages of [SII]/ Hα line ratios correlate with the masses of the dwarf galaxies following the previously established dwarf galaxy mass-metallicity relationship. The slope of the luminosity functions for the dwarf galaxies varies with galaxy mass. The Carleton Catalog of this Local Group Emission-line Survey will be made available on-line.

  20. Neon and [C II] 158 μm Emission Line Profiles in Dusty Starbursts and Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Samsonyan, Anahit; Weedman, Daniel; Lebouteiller, Vianney; Barry, Donald; Sargsyan, Lusine

    2016-09-01

    A sample of 379 extragalactic sources is presented that has mid-infrared, high-resolution spectroscopy from the Spitzer Infrared Spectrograph (IRS) and also spectroscopy of the [C ii] 158 μm line from the Herschel Photodetector Array Camera and Spectrometer (PACS). The emission line profiles of [Ne ii] 12.81 μm, [Ne iii] 15.55 μm, and [C ii] 158 μm are presented, and intrinsic line widths are determined (full width half maximum of Gaussian profiles after instrumental correction). All line profiles, together with overlays comparing the positions of PACS and IRS observations, are made available in the Cornell Atlas of Spitzer IRS Sources. Sources are classified from active galactic nucleus (AGN) to starburst based on equivalent widths of the 6.2 μm polycyclic aromatic hydrocarbon feature. It is found that intrinsic line widths do not change among classifications for [C ii], with median widths of 207 km s-1 for AGNs, 248 km s-1 for composites, and 233 km s-1 for starbursts. The [Ne ii] line widths also do not change with classification, but [Ne iii] lines are progressively broader from starburst to AGN. A few objects with unusually broad lines or unusual redshift differences in any feature are identified.

  1. Investigating Starburst Galaxy Emission Line Equivalent Widths

    NASA Astrophysics Data System (ADS)

    Meskhidze, Helen; Richardson, Chris T.

    2016-01-01

    Modeling star forming galaxies with spectral synthesis codes allows us to study the gas conditions and excitation mechanisms that are necessary to reproduce high ionization emission lines in both local and high-z galaxies. Our study uses the locally optimally-emitting clouds model to develop an atlas of starburst galaxy emission line equivalent widths. Specifically, we address the following question: What physical conditions are necessary to produce strong high ionization emission lines assuming photoionization via starlight? Here we present the results of our photoionization simulations: an atlas spanning 15 orders of magnitude in ionizing flux and 10 orders of magnitude in hydrogen density that tracks over 150 emission lines ranging from the UV to the near IR. Each simulation grid contains ~1.5x104 photoionization models calculated by supplying a spectral energy distribution, grain content, and chemical abundances. Specifically, we will be discussing the effects on the emission line equivalent widths of varying the metallicity of the cloud, Z = 0.2 Z⊙ to Z = 5.0 Z⊙, and varying the star-formation history, using the instantaneous and continuous evolution tracks and the newly released Starburst99 Geneva rotation tracks.

  2. Radio-optical scrutiny of compact AGN: correlations between properties of pc-scale jets and optical nuclear emission

    NASA Astrophysics Data System (ADS)

    Arshakian, T. G.; Torrealba, J.; Chavushyan, V. H.; Ros, E.; Lister, M. L.; Cruz-González, I.; Zensus, J. A.

    2010-09-01

    Aims: We study the correlations between the VLBA (Very Long Baseline Array) radio emission at 15 GHz, extended emission at 151 MHz, and optical nuclear emission at 5100 Å for a complete sample of 135 compact jets. Methods: We use the partial Kendall's tau correlation analysis to check the link between radio properties of parsec-scale jets and optical nuclear luminosities of host active galactic nuclei (AGN). Results: We find a significant positive correlation for 99 quasars between optical nuclear luminosities and total radio (VLBA) luminosities of unresolved cores at 15 GHz originated at milliarcseconds scales. For 18 BL Lacs, the optical continuum emission correlates with the radio emission of the jet at 15 GHz. We suggest that the radio and optical emission are beamed and originate in the innermost part of the sub-parsec-scale jet in quasars. Analysis of the relation between the apparent speed of the jet and the optical nuclear luminosity at 5100 Å supports the relativistic beaming model for the optical emission generated in the jet, and allows the peak values of the intrinsic optical luminosity of the jet and its Lorentz factor to be estimated for the populations of quasars (2×1020 W Hz-1 and γ = 52), BL Lacs (9×1021 W Hz-1 and γ = 20), and radio galaxies (1.5×1021 W Hz-1 and γ = 9). The radio-loudness of quasars (the ratio of 15 GHz flux density and optical nuclear flux at 5100 Å) is found to increase at high redshifts, which is interpreted as progressively higher Doppler factors in radio regime compared to those in optical. A strong positive correlation is found between the intrinsic kinetic power of the jet (measured from the flux density at 151 MHz) and the apparent luminosities of the total and the unresolved core emission of the jet at 15 GHz. This correlation is interpreted in terms of an intrinsically more luminous parsec-scale jet producing more luminous extended structure, which is detectable at low radio frequencies, 151 MHz. A possibility

  3. EXTENDED NARROW-LINE EMISSION IN THE BRIGHT SEYFERT 1.5 GALAXY HE 2211-3903

    SciTech Connect

    Scharwaechter, J.; Dopita, M. A.; Zuther, J.; Fischer, S.; Eckart, A.; Komossa, S.

    2011-08-15

    Extended narrow-line regions (ENLRs) and extended emission-line regions have been the focus of integral field spectroscopy aiming at the inner kiloparsecs of nearby Seyfert galaxies as well as the larger environment of high-redshift QSOs. Based on observations with the Wide Field Spectrograph at the 2.3 m telescope of the Australian National University, we present spatially resolved emission-line diagnostics of the bright Seyfert 1.5 galaxy HE 2211-3903 which is drawn from a sample of the brightest Seyfert galaxies at z < 0.06 with luminosities around the classical Seyfert/QSO demarcation. In addition to the previously known spiral arms of HE 2211-3903, the emission-line maps reveal a large-scale ring with a radius of about 6 kpc which is connected to the active galactic nucleus (AGN) through a bar-like structure. The overall gas kinematics indicates a disk rotation pattern. The emission-line ratios show Seyfert-type, H II region-type, and composite classifications, while there is no strong evidence of LINER-type ratios. Shock ionization is likely to be negligible throughout the galaxy. The composite line ratios are explained via a mixing line between AGN and H II region photoionization. Composite line ratios are predominantly found in between the H II regions in the circum-nuclear region, the bar-like structure to the east of the nucleus, and the eastern half of the ring, suggesting AGN photoionization of the low-density interstellar medium in an ENLR on galaxy scales. The line ratios in the nucleus indicate N enrichment, which is discussed in terms of chemical enrichment by Wolf-Rayet and asymptotic giant branch stars during past and ongoing nuclear starburst activity.

  4. Scattering of emission lines in galaxy cluster cores: measuring electron temperature

    NASA Astrophysics Data System (ADS)

    Khedekar, S.; Churazov, E.; Sazonov, S.; Sunyaev, R.; Emsellem, E.

    2014-06-01

    The central galaxies of some clusters can be strong emitters in the Lyα and Hα lines. This emission may arise either from the cool/warm gas located in the cool core of the cluster or from the bright AGN within the central galaxy. The luminosities of such lines can be as high as 1042-1044 erg s-1. This emission originating from the core of the cluster will get Thomson scattered by hot electrons of the intra-cluster medium with an optical depth ˜0.01 giving rise to very broad (Δλ/λ ˜ 15 per cent) features in the scattered spectrum. We discuss the possibility of measuring the electron density and temperature using information on the flux and width of the highly broadened line features.

  5. A new sample of X-ray selected narrow emission-line galaxies. II. Looking for True Seyfert 2

    NASA Astrophysics Data System (ADS)

    Pons, E.; Watson, M. G.

    2016-10-01

    A sample of X-ray and optically selected narrow emission-line galaxies (769 sources) from the 3XMM catalogue cross-correlated with SDSS (DR9) catalogue has been studied. Narrow-emission line active galactic nuclei (AGN; type-2) have been selected on the basis of their emission line ratios and/or X-ray luminosity. We have looked for X-ray unobscured type-2 AGN. As X-ray spectra were not available for our whole sample, we have checked the reliability of using the X-ray hardness ratio (HR) as a probe of the level of obscuration and we found a very good agreement with full spectral fitting results, with only 2% of the sources with apparently unobscured HR turning out to have an obscured spectrum. Despite the fact that type-2 AGN are supposed to be absorbed based on the Unified Model, about 60% of them show no sign or very low level of X-ray obscuration. After subtraction of contaminants to the sample, that is Narrow-Line Seyfert 1 and Compton-thick AGN, the fraction of unobscured Sy2 drops to 47%. For these sources, we were able to rule out dust reddening and variability for most of them as an explanation of the absence of optical broad emission-lines. The main explanations remaining are the dilution of weak/very broad emission-lines by the host galaxy and the intrinsic absence of the broad-line region (BLR) due to low accretion rates (i.e. True Sy2). However, the number of True Sy2 strongly depends on the method used to verify the intrinsic lack of broad lines. Indeed using the optical continuum luminosity to predict the BLR properties gives a much larger fraction of True Sy2 (about 90% of the unobscured Sy2 sample) than the use of the X-ray 2 keV luminosity (about 20%). Nevertheless the number of AGN we securely detected as True Sy2 is at least three times larger that the previously confirmed number of True Sy2.

  6. The Far-Infrared Emission Line and Continuum Spectrum of the Seyfert Galaxy NGC 1068

    NASA Astrophysics Data System (ADS)

    Spinoglio, Luigi; Malkan, Matthew A.; Smith, Howard A.; González-Alfonso, Eduardo; Fischer, Jacqueline

    2005-04-01

    We report on the analysis of the first complete far-infrared spectrum (43-197 μm) of the Seyfert 2 galaxy NGC 1068 as observed with the Long Wavelength Spectrometer (LWS) on board the Infrared Space Observatory (ISO). In addition to the seven expected ionic fine-structure emission lines, the OH rotational lines at 79, 119, and 163 μm were all detected in emission, which is unique among galaxies with full LWS spectra, where the 119 μm line, when detected, is always in absorption. The observed line intensities were modeled together with ISOShort Wavelength Spectrometer (SWS) and optical and ultraviolet line intensities from the literature, considering two independent emission components: the active galactic nucleus (AGN) component and the starburst component in the circumnuclear ring of ~3 kpc in size. Using the UV to mid-IR emission line spectrum to constrain the nuclear ionizing continuum, we have confirmed previous results: a canonical power-law ionizing spectrum is a poorer fit than one with a deep absorption trough, while the presence of a `` big blue bump'' is ruled out. Based on the instantaneous starburst age of 5 Myr constrained by the Brγ equivalent width in the starburst ring, and starburst synthesis models of the mid- and far-infrared fine-structure line emission, a low-ionization parameter (U=10-3.5) and low densities (n=100 cm-3) are derived. Combining the AGN and starburst components, we succeeded in modeling the overall UV to far-IR atomic spectrum of NGC 1068, reproducing the line fluxes to within a factor of 2.0 on average with a standard deviation of 1.3, and the overall continuum as the sum of the contribution of the thermal dust emission in the ionized and neutral components. The OH 119 μm emission indicates that the line is collisionally excited and arises in a warm and dense region. The OH emission has been modeled using spherically symmetric, nonlocal, non-LTE radiative transfer models. The models indicate that the bulk of the emission

  7. EFFECTS OF AN ACCRETION DISK WIND ON THE PROFILE OF THE BALMER EMISSION LINES FROM ACTIVE GALACTIC NUCLEI

    SciTech Connect

    Flohic, Helene M. L. G.; Eracleous, Michael; Bogdanovic, Tamara E-mail: mce@astro.psu.edu

    2012-07-10

    We explore the connection between active galactic nuclei (AGNs) with single- and double-peaked broad Balmer emission lines by using models dealing with radiative transfer effects through a disk wind. Our primary goal is to assess the applicability of the Murray and Chiang model by making an extensive and systematic comparison of the model predictions with data. In the process, we also verify the original derivation and evaluate the importance of general relativistic effects. As the optical depth through the emission layer increases, the peaks of a double-peaked profile move closer and eventually merge, producing a single peak. The properties of the emission line profile depend as sensitively on the geometric parameters of the line-emitting portion of the disk as they do on the disk-wind parameters. Using a parameter range that encompasses the expected characteristics of the broad-line regions in AGNs, we construct a database of model profiles and measure a set of diagnostic properties. Comparisons of the model profiles with emission lines from a subset of Sloan digital Sky Survey quasars show that observed lines are consistent with moderately large optical depth in the disk wind and a range of disk inclinations i {approx}< 45 Degree-Sign . Including relativistic effects is necessary to produce the asymmetries of observed line profiles.

  8. ULTRAVIOLET EMISSION-LINE CORRELATIONS IN HST/COS SPECTRA OF ACTIVE GALACTIC NUCLEI: SINGLE-EPOCH BLACK HOLE MASSES

    SciTech Connect

    Tilton, Evan M.; Shull, J. Michael E-mail: michael.shull@colorado.edu

    2013-09-01

    Effective methods of measuring supermassive black hole masses in active galactic nuclei (AGNs) are of critical importance to studies of galaxy evolution. While there has been much success in obtaining masses through reverberation mapping, the extensive observing time required by this method has limited the practicality of applying it to large samples at a variety of redshifts. This limitation highlights the need to estimate these masses using single-epoch spectroscopy of ultraviolet (UV) emission lines. We use UV spectra of 44 AGNs from HST/COS, the International Ultraviolet Explorer, and the Far Ultraviolet Spectroscopic Explorer of the C IV {lambda}1549, O VI {lambda}1035, O III] {lambda}1664, He II {lambda}1640, C II {lambda}1335, and Mg II {lambda}2800 emission lines and explore their potential as tracers of the broad-line region and supermassive black hole mass. The higher signal-to-noise ratio and better spectral resolution of the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST) resolve AGN intrinsic absorption and produce more accurate line widths. From these, we test the viability of mass-scaling relationships based on line widths and luminosities and carry out a principal component analysis based on line luminosities, widths, skewness, and kurtosis. At L{sub 1450} {<=} 10{sup 45} erg s{sup -1}, the UV line luminosities correlate well with H{beta}, as does the 1450 A continuum luminosity. We find that C IV, O VI, and Mg II can be used as reasonably accurate estimators of AGN black hole masses, while He II and C II are uncorrelated.

  9. The Far-Infrared Emission Line and Continuum Spectrum of the Seyfert Galaxy NGC 1068

    NASA Technical Reports Server (NTRS)

    Spinoglio, Luigi; Smith, Howard A.; Gonzalez-Alfonso, Eduardo; Fisher, Jacqueline

    2005-01-01

    We report on the analysis of the first complete far-infrared spectrum (43-197 microns) of the Seyfert 2 galaxy NGC 1068 as observed with the Long Wavelength Spectrometer (LWS) onboard the Infrared Space Observatory (ISO). In addition to the 7 expected ionic fine structure emission lines, the OH rotational lines at 79, 119 and 163 microns were all detected in emission, which is unique among galaxies with full LWS spectra, where the 119 micron line, where detected, is always in absorption. The observed line intensities were modelled together with IS0 Short Wavelength Spectrometer (SWS) and optical and ultraviolet line intensities from the literature, considering two independent emission components: the AGN component and the starburst component in the circumnuclear ring of approximately 3kpc in size. Using the UV to mid-IR emission line spectrum to constrain the nuclear ionizing continuum, we have confirmed previous results: a canonical power-law ionizing spectrum is a poorer fit than one with a deep absorption trough, while the presence of a big blue bump is ruled out. Based on the instantaneous starburst age of 5 Myr constrained by the Br gamma equivalent width in the starburst ring, and starburst synthesis models of the mid- and far-infrared fine-structure line emission, a low ionization parameter (U=10(exp -3.5)) and low densities (n=100 cm (exp -3)) are derived. Combining the AGN and starburst components, we succeed in modeling the overall UV to far-IR atomic spectrum of SGC 1068, reproducing the line fluxes to within a factor 2.0 on average with a standard deviation of 1.4. The OH 119 micron emission indicates that the line is collisionally excited, and arises in a warm and dense region. The OH emission has been modeled using spherically symmetric, non-local, non-LTE radiative transfer models. The models indicate that the bulk of the emission arises from the nuclear region, although some extended contribution from the starburst is not ruled out. The OH abundance

  10. The Prevalence of Gas Outflows in Type 2 AGNs

    NASA Astrophysics Data System (ADS)

    Woo, Jong-Hak; Bae, Hyun-Jin; Son, Donghoon; Karouzos, Marios

    2016-02-01

    To constrain the nature and fraction of the ionized gas outflows in active galactic nuclei (AGNs), we perform a detailed analysis on gas kinematics as manifested by the velocity dispersion and shift of the [{{O}}\\{{III}}] λ5007 emission line, using a large sample of ˜39,000 type 2 AGNs at z < 0.3. First, we confirm a broad correlation between [{{O}} {{III}}] and stellar velocity dispersions, indicating that the bulge gravitational potential plays a main role in determining the [{{O}} {{III}}] kinematics. However, [{{O}} {{III}}] velocity dispersion is on average larger than stellar velocity dispersion by a factor of 1.3-1.4 for AGNs with double Gaussian [{{O}} {{III}}], suggesting that the non-gravitational component, i.e., outflows, is almost comparable to the gravitational component. Second, the increase of the [{{O}} {{III}}] velocity dispersion (after normalized by stellar velocity dispersion) with both AGN luminosity and Eddington ratio suggests that non-gravitational kinematics are clearly linked to AGN accretion. The distribution in the [{{O}} {{III}}] velocity-velocity dispersion diagram dramatically expands toward large values with increasing AGN luminosity, implying that the launching velocity of gas outflows increases with AGN luminosity. Third, the majority of luminous AGNs present the non-gravitational kinematics in the [{{O}} {{III}}] profile. These results suggest that ionized gas outflows are prevalent among type 2 AGNs. On the other hand, we find no strong trend of the [{{O}} {{III}}] kinematics with radio luminosity, once we remove the effect of the bulge gravitational potential, indicating that ionized gas outflows are not directly related to radio activity for the majority of type 2 AGNs.

  11. TIME VARIABLE BROAD-LINE EMISSION IN NGC 4203: EVIDENCE FOR STELLAR CONTRAILS

    SciTech Connect

    Devereux, Nick

    2011-12-10

    Dual epoch spectroscopy of the lenticular galaxy, NGC 4203, obtained with the Hubble Space Telescope has revealed that the double-peaked component of the broad H{alpha} emission line is time variable, increasing by a factor of 2.2 in brightness between 1999 and 2010. Modeling the gas distribution responsible for the double-peaked profiles indicates that a ring is a more appropriate description than a disk and most likely represents the contrail of a red supergiant star that is being tidally disrupted at a distance of {approx}1500 AU from the central black hole. There is also a bright core of broad H{alpha} line emission that is not time variable and identified with a large-scale inflow from an outer radius of {approx}1 pc. If the gas number density is {>=}10{sup 6} cm{sup -3}, as suggested by the absence of similarly broad [O I] and [O III] emission lines, then the steady state inflow rate is {approx} 2 Multiplication-Sign 10{sup -2} M{sub Sun} yr{sup -1}, which exceeds the inflow requirement to explain the X-ray luminosity in terms of radiatively inefficient accretion by a factor of {approx}6. The central active galactic nucleus (AGN) is unable to sustain ionization of the broad-line region; the discrepancy is particularly acute in 2010 when the broad H{alpha} emission line is dominated by the contrail of the infalling supergiant star. However, ram pressure shock ionization produced by the interaction of the infalling supergiant with the ambient interstellar medium may help alleviate the ionizing deficit by generating a mechanical source of ionization supplementing the photoionization provided by the AGN.

  12. 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.

  13. Extreme optical Fe II emission in luminous IRAS active galactic nuclei

    NASA Technical Reports Server (NTRS)

    Lipari, Sebastian; Terlevich, Roberto; Macchetto, F.

    1993-01-01

    Results of a program of studies and observations of strong optical Fe II emission in luminous and ultraluminous IRAS AGN are presented. New spectroscopic observations and studies of three known ultraluminous IRAS AGN with extreme optical Fe II emission, the discovery that PHL 1092 is a new ultraluminous IRAS AGN, and the detection of two new AGN with strongly variable flux in the optical Fe II emission lines are reported. These results are used to test the correlations between the Fe II emission and properties at other wavelengths such as the L(IR) and the radio emission. IR AGN with extreme Fe II emission are found to belong to a very important group of AGN, whose properties provide insight into the origin of the extreme Fe II emission and into the relation between the starburst and AGN phenomena.

  14. CONNECTION BETWEEN MID-INFRARED EMISSION PROPERTIES AND NARROW-LINE REGION OUTFLOWS IN TYPE 1 ACTIVE GALACTIC NUCLEI

    SciTech Connect

    Zhang Kai; Wang Tinggui; Dong Xiaobo; Yan Lin

    2013-05-01

    The location of warm dust producing the mid-infrared (MIR) emission in type 1 active galactic nuclei (AGNs) is complex and not yet fully known. We explore this problem by studying how the MIR covering factor (CF{sub MIR} = L{sub MIR}/L{sub bol}) correlates with the fundamental parameters of AGN accretion process (such as L{sub bol}, black hole mass M{sub BH}, and Eddington ratio L/L{sub Edd}) and the properties of narrow emission lines (as represented by [O III] {lambda}5007), using large data sets derived from the Sloan Digital Sky Spectroscopic Survey (SDSS) and the Wide Infrared Sky Survey (WISE). First, we find that the luminosity of the [O III] wing component (L{sub wing}) correlates more tightly with the continuum luminosity ({lambda}L{sub {lambda}}(5100)) than the luminosity of the line core component (L{sub core}) does, which is in line with our previous conclusion that the wing component, generally blueshifted, originates from the polar outflows in the inner narrow-line region (NLR). We then find that the MIR CF shows the strongest correlation with L{sub wing}/L{sub bol} rather than with L{sub core}/L{sub bol} or the above fundamental AGN parameters, and the correlation becomes stronger as the infrared wavelength increases. We also confirm the anti-correlations of CF{sub MIR} with L{sub bol} and M{sub BH}, and the lack of dependence of CF{sub MIR} on the Eddington ratio. These results suggest that a large fraction of the warm dust producing MIR emission in AGNs is likely embedded in polar outflows in the NLR instead of in the torus.

  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. Spectral properties of X-ray selected narrow emission line galaxies

    NASA Astrophysics Data System (ADS)

    Romero-Colmenero, E.

    1998-03-01

    This thesis reports a study of the X-ray and optical properties of two samples of X-ray selected Narrow Emission Line Galaxies (NELGs), and their comparison with the properties of broad line Active Galactic Nuclei (AGN). One sample (18 NELGs) is drawn from the ROSAT International X-ray Optical Survey (RIXOS), the other (19 NELGs and 33 AGN) from the ROSAT UK Deep Survey. ROSAT multi-channel X-ray spectra have been extracted and fitted with power-law, bremsstrahlung and black body models for the brighter RIXOS sources. In most cases, power-law and bremsstrahlung models provide the best results. The average spectral energy index, alpha, of the RIXOS NELGs is 0.96 +/- 0.07, similar to that of AGN (alpha~1). For the fainter RIXOS NELGs, as well as for all the UK Deep Survey sources, counts in three spectral bands have been extracted and fitted with a power-law model, assuming the Galactic value for N_H. The brighter RIXOS sources demonstrated that the results obtained by these two different extraction and fitting procedures provide consistent results. Two average X-ray spectra, one for the NELGs and another for the AGN, were created from the UK Deep Survey sources. The power-law slope of the average NELG is alpha = 0.45 +/- 0.09, whilst that of the AGN is alpha = 0.96 +/- 0.03. ROSAT X-ray surveys have shown that the fractional surface density of NELGs increases with respect to AGN at faint fluxes (<= 2e-15 ergs cm-2 s-1), thus suggesting that NELGs are important contributors to the residual soft (<2 keV) X-ray background (XRB). Moreover, the spectral slope of this background (alpha~0.4, 1-10 keV) is harder than that of AGN (alpha~1), which are known to contribute most of the XRB at higher flux levels. The work presented in this thesis shows unequivocally for the first time that the integrated spectrum of the faintest NELGs (alpha~0.4) is consistent with that of the soft X-ray background, finally reconciling it with the properties of the sources that are thought to

  17. Spectral properties of x-ray selected narrow emission line galaxies

    NASA Astrophysics Data System (ADS)

    Romero Colmenero, Encarnacion

    This thesis reports a study of the X-ray and optical properties of two samples of X-ray selected Narrow Emission Line Galaxies (NELGs), and their comparison with the properties of broad line Active Galactic Nuclei (AGN). One sample (18 NELGs) is drawn from the ROSAT International X-ray Optical Survey (RIXOS), the other (19 NELGs and 33 AGN) from the ROSAT UK Deep Survey. ROSAT multi-channel X-ray spectra have been extracted and fitted with power-law, bremsstrahlung and black body models for the brighter RIXOS sources. In most cases, power-law and bremsstrahlung models provide the best results. The average spectral energy index, alpha, of the RIXOS NELGs is 0.96 +/- 0.07, similar to that of AGN (alpha ~ 1). For the fainter RIXOS NELGs, as well as for all the UK Deep Survey sources, counts in three spectral bands have been extracted and fitted with a power-law model, assuming the Galactic value for NH. The brighter RIXOS sources demonstrated that the results obtained by these two different extraction and fitting procedures provide consistent results. Two average X-ray spectra, one for the NELGs and another for the AGN, were created from the UK Deep Survey sources. The power-law spectral slope of the average NELG is S = 0.45 +/- 0.09, whilst that of the AGN is S = 0.96 +/- 0.03. ROSAT X-ray surveys have shown that the fractional surface density of NELGs increases with respect to AGN at faint fluxes (< 2 x 10-15erg cm-2 s -1), thus suggesting that NELGs are important contributors to the residual soft (< 2 keV) X-ray background (XRB). Moreover, the spectral slope of this background (S ~ 0.4, 1-10 keV) is harder than that of AGN (S ~ 1), which are known to contribute most of the XRB at higher flux levels. The work presented in this thesis shows unequivocally for the first time that the integrated spectrum of the faintest NELGs (alpha ~ 0.4) is consistent with that of the soft X-ray background, finally reconciling it with the properties of the sources that are thought to

  18. The dependence of X-ray AGN activity on host galaxy properties and environment

    NASA Astrophysics Data System (ADS)

    Tasse, C.; Röttgering, H.; Best, P. N.

    2011-01-01

    There is mounting evidence that active galactic nuclei (AGN) selected through optical emission lines or radio luminosities comprise two distinct AGN populations, whose activity is triggered by different processes. In two previous papers, we studied the host galaxies and environment of radio-loud AGN. In this third paper we study the properties of a sample of Type-2 AGN that were selected on the basis of their [2-10] keV X-ray luminosity. We find that the X-ray luminosity function is in good agreement with previous studies and that the fraction of galaxies hosting an X-ray AGN is a strong function of the stellar mass of the host galaxy. The shape of this fraction-mass relation is similar to the fraction of galaxies that are emission-line AGN, while it differs significantly from the relation observed for radio-selected AGN. The AGN in our sample tend to be located in underdense environments where galaxy mergers and interactions are likely to occur. For all host galaxy masses, the Type-2 AGN display a strong infrared excess at short (~3.5 μm) wavelengths, suggesting the presence of hot dust possibly associated with a hot dusty torus. These results add weight to the belief that the X-ray selection criteria identifies a population of AGN similar to the emission-line selected population but distinct from the radio population at high masses. Appendix A is only available in electronic form at http://www.aanda.org

  19. 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.

  20. Millimeter emission lines in Orion A

    NASA Technical Reports Server (NTRS)

    Lovas, F. J.; Johnson, D. R.; Buhl, D.; Snyder, L. E.

    1976-01-01

    During the course of a search of Orion A for signals from three large organic molecules, several millimeter-wave lines from known interstellar molecules were observed. Results are reported for observations of methanol (CH3OH), methyl cyanide (CH3CN), methyl acetylene (CH3CCH), acetaldehyde (CH3CHO) and (Si-29)O. Emission signals from two hydrogen recombination lines (H41-alpha and H42-alpha) detected from the H II region of Orion A are also reported. Negative results were obtained for several millimeter-wave transitions of ethylene oxide, acetone, and cyclopropenone.

  1. ALMA Imaging of the CO (6-5) Line Emission in NGC 7130*

    NASA Astrophysics Data System (ADS)

    Zhao, Yinghe; Lu, Nanyao; Xu, C. Kevin; Gao, Yu; Barcos-Munõz, Loreto; Díaz-Santos, Tanio; Appleton, Philip; Charmandaris, Vassilis; Armus, Lee; van der Werf, Paul; Evans, Aaron; Cao, Chen; Inami, Hanae; Murphy, Eric

    2016-04-01

    In this paper, we report our high-resolution (0.″20 × 0.″14 or ˜70 × 49 pc) observations of the CO(6-5) line emission, which probes warm and dense molecular gas, and the 434 μm dust continuum in the nuclear region of NGC 7130, obtained with the Atacama Large Millimeter Array (ALMA). The CO line and dust continuum fluxes detected in our ALMA observations are 1230 ± 74 Jy km s-1 and 814 ± 52 mJy, respectively, which account for 100% and 51% of their total fluxes. We find that the CO(6-5) and dust emissions are generally spatially correlated, but their brightest peaks show an offset of ˜70 pc, suggesting that the gas and dust emissions may start decoupling at this physical scale. The brightest peak of the CO(6-5) emission does not spatially correspond to the radio continuum peak, which is likely dominated by an active galactic nucleus (AGN). This, together with our additional quantitative analysis, suggests that the heating contribution of the AGN to the CO(6-5) emission in NGC 7130 is negligible. The CO(6-5) and the extinction-corrected Pa-α maps display striking differences, suggestive of either a breakdown of the correlation between warm dense gas and star formation at linear scales of <100 pc or a large uncertainty in our extinction correction to the observed Pa-α image. Over a larger scale of ˜2.1 kpc, the double-lobed structure found in the CO(6-5) emission agrees well with the dust lanes in the optical/near-infrared images. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

  2. Magnetically elevated accretion disks in active galactic nuclei: broad emission line regions and associated star formation

    NASA Astrophysics Data System (ADS)

    Begelman, Mitchell C.; Silk, Joseph

    2016-10-01

    We propose that the accretion disks fueling active galactic nuclei are supported vertically against gravity by a strong toroidal (φ -direction) magnetic field that develops naturally as the result of an accretion disk dynamo. The magnetic pressure elevates most of the gas carrying the accretion flow at R to large heights z ˜ 0.1 R and low densities, while leaving a thin dense layer containing most of the mass - but contributing very little accretion - around the equator. We show that such a disk model leads naturally to the formation of a broad emission line region through thermal instability. Extrapolating to larger radii, we demonstrate that local gravitational instability and associated star formation are strongly suppressed compared to standard disk models for AGN, although star formation in the equatorial zone is predicted for sufficiently high mass supply rates. This new class of accretion disk models thus appears capable of resolving two longstanding puzzles in the theory of AGN fueling: the formation of broad emission line regions and the suppression of fragmentation thought to inhibit accretion at the required rates. We show that the disk of stars that formed in the Galactic Center a few million years ago could have resulted from an episode of magnetically elevated accretion at ˜0.1 of the Eddington limit.

  3. Linear Polarization Measurements of Chromospheric Emission Lines

    NASA Technical Reports Server (NTRS)

    Sheeley, N. R., Jr.; Keller, C. U.

    2003-01-01

    We have used the Zurich Imaging Stokes Polarimeter (ZIMPOL I) with the McMath-Pierce 1.5 m main telescope on Kitt Peak to obtain linear polarization measurements of the off-limb chromosphere with a sensitivity better than 1 x 10(exp -5). We found that the off-disk observations require a combination of good seeing (to show the emission lines) and a clean heliostat (to avoid contamination by scattered light from the Sun's disk). When these conditions were met, we obtained the following principal results: 1. Sometimes self-reversed emission lines of neutral and singly ionized metals showed linear polarization caused by the transverse Zeeman effect or by instrumental cross talk from the longitudinal Zeeman effect in chromospheric magnetic fields. Otherwise, these lines tended to depolarize the scattered continuum radiation by amounts that ranged up to 0.2%. 2. Lines previously known to show scattering polarization just inside the limb (such as the Na I lambda5889 D2 and the He I lambda5876 D3 lines) showed even more polarization above the Sun's limb, with values approaching 0.7%. 3. The O I triplet at lambda7772, lambda7774, and lambda7775 showed a range of polarizations. The lambda7775 line, whose maximum intrinsic polarizability, P(sub max), is less than 1%, revealed mainly Zeeman contributions from chromospheric magnetic fields. However, the more sensitive lambda7772 (P(sub max) = 19%) and lambda7774 (P(sub max) = 29%) lines had relatively strong scattering polarizations of approximately 0.3% in addition to their Zeeman polarizations. At times of good seeing, the polarization spectra resolve into fine structures that seem to be chromospheric spicules.

  4. Observations of southern emission-line stars

    NASA Technical Reports Server (NTRS)

    Henize, K. G.

    1976-01-01

    A catalog of 1929 stars showing H-alpha emission on photographic plates is presented which covers the entire southern sky south of declination -25 deg to a red limiting magnitude of about 11.0. The catalog provides previous designations of known emission-line stars equatorial (1900) and galactic coordinates, visual and photographic magnitudes, H-alpha emission parameters, spectral types, and notes on unusual spectral features. The objects listed include 16 M stars, 25 S stars, 37 carbon stars, 20 symbiotic stars, 40 confirmed or suspected T Tauri stars, 16 novae, 14 planetary nebulae, 11 P Cygni stars, 9 Bep stars, 87 confirmed or suspected Wolf-Rayet stars, and 26 'peculiar' stars. Two new T associations are discovered, one in Lupus and one in Chamaeleon. Objects with variations in continuum or H-alpha intensity are noted, and the distribution by spectral type is analyzed. It is found that the sky distribution of these emission-line stars shows significant concentrations in the region of the small Sagittarius cloud and in the Carina region.

  5. 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.

  6. CORA: Emission Line Fitting with Maximum Likelihood

    NASA Astrophysics Data System (ADS)

    Ness, Jan-Uwe; Wichmann, Rainer

    2011-12-01

    The advent of pipeline-processed data both from space- and ground-based observatories often disposes of the need of full-fledged data reduction software with its associated steep learning curve. In many cases, a simple tool doing just one task, and doing it right, is all one wishes. In this spirit we introduce CORA, a line fitting tool based on the maximum likelihood technique, which has been developed for the analysis of emission line spectra with low count numbers and has successfully been used in several publications. CORA uses a rigorous application of Poisson statistics. From the assumption of Poissonian noise we derive the probability for a model of the emission line spectrum to represent the measured spectrum. The likelihood function is used as a criterion for optimizing the parameters of the theoretical spectrum and a fixed point equation is derived allowing an efficient way to obtain line fluxes. As an example we demonstrate the functionality of the program with an X-ray spectrum of Capella obtained with the Low Energy Transmission Grating Spectrometer (LETGS) on board the Chandra observatory and choose the analysis of the Ne IX triplet around 13.5 Å.

  7. CORA - emission line fitting with Maximum Likelihood

    NASA Astrophysics Data System (ADS)

    Ness, J.-U.; Wichmann, R.

    2002-07-01

    The advent of pipeline-processed data both from space- and ground-based observatories often disposes of the need of full-fledged data reduction software with its associated steep learning curve. In many cases, a simple tool doing just one task, and doing it right, is all one wishes. In this spirit we introduce CORA, a line fitting tool based on the maximum likelihood technique, which has been developed for the analysis of emission line spectra with low count numbers and has successfully been used in several publications. CORA uses a rigorous application of Poisson statistics. From the assumption of Poissonian noise we derive the probability for a model of the emission line spectrum to represent the measured spectrum. The likelihood function is used as a criterion for optimizing the parameters of the theoretical spectrum and a fixed point equation is derived allowing an efficient way to obtain line fluxes. As an example we demonstrate the functionality of the program with an X-ray spectrum of Capella obtained with the Low Energy Transmission Grating Spectrometer (LETGS) on board the Chandra observatory and choose the analysis of the Ne IX triplet around 13.5 Å.

  8. The line continuum luminosity ratio in AGN: Or on the Baldwin Effect

    NASA Technical Reports Server (NTRS)

    Mushotzky, R.; Ferland, F. J.

    1983-01-01

    The luminosity dependence of the equivalent width of CIV in active galaxies, the "Baldwin" effect, is shown to be a consequence of a luminosity dependent ionization parameter. This law also agrees with the lack of a "Baldwin" effect in Ly alpha or other hydrogen lines. A fit to the available data gives a weak indication that the mean covering factor decreases with increasing luminosity, consistent with the inference from X-ray observations. The effects of continuum shape and density on various line ratios of interest are discussed.

  9. 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.

  10. 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.

  11. Active galactic nuclei at z ˜ 1.5 - II. Black hole mass estimation by means of broad emission lines

    NASA Astrophysics Data System (ADS)

    Mejía-Restrepo, J. E.; Trakhtenbrot, B.; Lira, P.; Netzer, H.; Capellupo, D. M.

    2016-07-01

    This is the second in a series of papers aiming to test how the mass (MBH), accretion rate (Ṁ) and spin (a*) of supermassive black holes (SMBHs) determine the observed properties of type I active galactic nuclei (AGN). Our project utilizes a sample of 39 unobscured AGN at z ≃ 1.55 observed by Very Large Telescope/X-Shooter, selected to map a large range in MBH and L/LEdd and covers the most prominent UV-optical (broad) emission lines, including Hα, Hβ, Mg II λ2798 and C IV λ1549. This paper focuses on single-epoch, `virial' MBH determinations from broad emission lines and examines the implications of different continuum modelling approaches in line width measurements. We find that using a local power-law continuum instead of a physically motivated thin disc continuum leads to only slight underestimation of the full width at half-maximum (FWHM) of the lines and the associated MBH(FWHM). However, the line dispersion σline and associated MBH(σline) are strongly affected by the continuum placement and provides less reliable mass estimates than FWHM-based methods. Our analysis shows that Hα, Hβ and Mg II can be safely used for virial MBH estimation. The C IV line, on the other hand, is not reliable in the majority of the cases; this may indicate that the gas emitting this line is not virialized. While Hα and Hβ show very similar line widths, the mean FWHM(Mg II) is about 30 per cent narrower than FWHM(Hβ). We confirm several recent suggestions to improve the accuracy in C IV-based mass estimates, relying on other UV emission lines. Such improvements do not reduce the scatter between C IV-based and Balmer-line-based mass estimates.

  12. 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.

  13. 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.

  14. SPATIALLY RESOLVED HST GRISM SPECTROSCOPY OF A LENSED EMISSION LINE GALAXY AT z {approx} 1

    SciTech Connect

    Frye, Brenda L.; Hurley, Mairead; Bowen, David V.; Meurer, Gerhardt; Sharon, Keren; Straughn, Amber; Coe, Dan; Broadhurst, Tom; Guhathakurta, Puragra

    2012-07-20

    We take advantage of gravitational lensing amplification by A1689 (z 0.187) to undertake the first space-based census of emission line galaxies (ELGs) in the field of a massive lensing cluster. Forty-three ELGs are identified to a flux of i{sub 775} = 27.3 via slitless grism spectroscopy. One ELG (at z = 0.7895) is very bright owing to lensing magnification by a factor of Almost-Equal-To 4.5. Several Balmer emission lines (ELs) detected from ground-based follow-up spectroscopy signal the onset of a major starburst for this low-mass galaxy (M{sub *} Almost-Equal-To 2 Multiplication-Sign 10{sup 9} M{sub Sun }) with a high specific star formation rate ( Almost-Equal-To 20 Gyr{sup -1}). From the blue ELs we measure a gas-phase oxygen abundance consistent with solar (12+log(O/H) = 8.8 {+-} 0.2). We break the continuous line-emitting region of this giant arc into seven {approx}1 kpc bins (intrinsic size) and measure a variety of metallicity-dependent line ratios. A weak trend of increasing metal fraction is seen toward the dynamical center of the galaxy. Interestingly, the metal line ratios in a region offset from the center by {approx}1 kpc have a placement on the blue H II region excitation diagram with f ([O III])/f (H{beta}) and f ([Ne III])/f (H{beta}) that can be fitted by an active galactic nucleus (AGN). This asymmetrical AGN-like behavior is interpreted as a product of shocks in the direction of the galaxy's extended tail, possibly instigated by a recent galaxy interaction.

  15. Characterizing the redshifts and luminosities of WISE selected obscured AGN using SALT optical spectra.

    NASA Astrophysics Data System (ADS)

    Hviding, Raphael E.; Hickox, Ryan C.; Hainline, Kevin N.; Carroll, Christopher M.; DiPompeo, Mike A.; Jones, Mackenzie L.

    2016-08-01

    We present the results of several optical spectroscopic surveys covering over 100 candidate luminous obscured active galactic nuclei (AGN) identified by their mid-infrared emission detected with the Wide-Field Infrared Survey Explorer (WISE). These galaxies were selected based on red WISE colors and galaxy-like optical emission, and were studied using long-slit optical spectroscopy with the Robert Stobie Spectrograph (RSS) on the Southern African Large Telescope (SALT). Our spectra were analyzed to obtain redshifts and emission line flux ratios for each galaxy. These results verify that WISE is an effective section method for luminous obscured AGN, allow for the characterization of redshifts and luminosities of the WISE color selected obscured AGN population, and could potentially contribute to large statistical studies of obscured AGN distributions in the future.

  16. 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

  17. Ultraviolet high-excitation Fe II fluorescence lines excited by O VI, C IV, and H I resonance emission as seen in IUE spectra

    NASA Technical Reports Server (NTRS)

    Feibelman, Walter A.; Bruhweiler, Frederick C.; Johansson, Sveneric

    1991-01-01

    Archival high-dispersion spectra from the IUE are used in a search for Bowen emission lines of Fe II excited by the stronger transition of the O VI resonance doublet. The possibility of using these Fe II emission lines as a diagnostic of the strength of the far-ultraviolet emission of O VI at 1032 A is explored. It is found that the Fe II emission lines are quite common and strong in symbiotic stars, particularly those of the type known as 'symbiotic novae', as well as in normal novae. The lines are observed in central stars of some planetary nebulae of the O VI sequence besides a few central stars of type WR. High density, high excitation, and high temperature are suggested to be requirements for the excitation of the Fe II fluorescence lines. It is pointed out that while these lines were observed in PG 1159-035 and K1-16, they were not observed in AGNs.

  18. AGN-2979, an inhibitor of tryptophan hydroxylase activation, does not affect serotonin synthesis in Flinders Sensitive Line rats, a rat model of depression, but produces a significant effect in Flinders Resistant Line rats.

    PubMed

    Kanemaru, Kazuya; Nishi, Kyoko; Diksic, Mirko

    2009-12-01

    The neurotransmitter, serotonin, is involved in several brain functions, including both normal, physiological functions, and pathophysiological functions. Alterations in any of the normal parameters of serotonergic neurotransmission can produce several different psychiatric disorders, including major depression. In many instances, brain neurochemical variables are not able to be studied properly in humans, thus making the use of good animal models extremely valuable. One of these animal models is the Flinders Sensitive Line (FSL) of rats, which has face, predictive and constructive validities in relation to human depression. The objective of this study was to quantify the effect of the tryptophan hydroxylase (TPH) activation inhibitor, AGN-2979, on the FSL rats (rats with depression-like behaviour), and compare it to the effect on the Flinders Resistant Line (FRL) of rats used as the control rats. The effect was evaluated by measuring changes in regional serotonin synthesis in the vehicle treated rats (FSL-VEH and FRL-VEH) relative to those measured in the AGN-2979 treated rats (FSL-AGN and FRL-AGN). Regional serotonin synthesis was measured autoradiographically in more than 30 brain regions. The measurements were performed using alpha-[(14)C]methyl-l-tryptophan as the tracer. The results indicate that AGN-2979 did not produce a significant reduction of TPH activity in the AGN-2979 group relative to the vehicle group (a reduction would have been observed if there had been an activation of TPH by the experimental setup) in the FSL rats. On the other hand, there was a highly significant reduction of synthesis in the FRL rats treated by AGN-2979, relative to the vehicle group. Together, the results demonstrate that in the FSL rats, AGN-2979 does not affect serotonin synthesis. This suggests that there was no activation of TPH in the FSL rats during the experimental procedure, but such activation did occur in the FRL rats. Because of this finding, it could be

  19. AGN-2979, an inhibitor of tryptophan hydroxylase activation, does not affect serotonin synthesis in Flinders Sensitive Line rats, a rat model of depression, but produces a significant effect in Flinders Resistant Line rats

    PubMed Central

    Kanemaru, Kazuya; Nishi, Kyoko; Diksic, Mirko

    2009-01-01

    The neurotransmitter, serotonin, is involved in several brain functions, including both normal, physiological functions, and pathophysiological functions. Alterations in any of the normal parameters of serotonergic neurotransmission can produce several different psychiatric disorders, including major depression. In many instances, brain neurochemical variables are not able to be studied properly in humans, thus making the use of good animal models extremely valuable. One of these animal models is the Flinders Sensitive Line (FSL) of rats, which has face, predictive and constructive validities in relation to human depression. The objective of this study was to quantify the effect of the tryptophan hydroxylase (TPH) activation inhibitor, AGN-2979, on the FSL rats (rats with depression-like behaviour), and compare it to the effect on the Flinders Resistant Line (FRL) of rats used as the control rats. The effect was evaluated by measuring changes in regional serotonin synthesis in the vehicle treated rats (FSL-VEH and FRL-VEH) relative to those measured in the AGN-2979 treated rats (FSL-AGN and FRL-AGN). Regional serotonin synthesis was measured autoradiographically in more than thirty brain regions. The measurements were performed using α-[14C]methyl-L-tryptophan as the tracer. The results indicate that AGN-2979 did not produce a significant reduction of TPH activity in the AGN-2979 group relative to the vehicle group (a reduction would have been observed if there had been an activation of TPH by the experimental set up) in the FSL rats. On the other hand, there was a highly significant reduction of synthesis in the FRL rats treated by AGN-2979, relative to the vehicle group. Together, the results demonstrate that in the FSL rats, AGN-2979 does not affect serotonin synthesis. This suggests that there was no activation of TPH in the FSL rats during the experimental procedure, but such activation did occur in the FRL rats. Because of this finding, it could be

  20. Mini-Survey of SDSS OIII AGN with Swift

    NASA Technical Reports Server (NTRS)

    Angelina, Lorella; George, Ian

    2007-01-01

    There is a common wisdom that every massive galaxy has a massive block hole. However, most of these objects either are not radiating or until recently have been very difficult to detect. The Sloan Digital Sky Survey (SDSS) data, based on the [OIII] line indicate that perhaps up to 20% of all galaxies may be classified as AGN a surprising result that must be checked with independent data. X-ray surveys have revealed that hard X-ray selected AGN show a strong luminosity dependent evolution and their luminosity function (LF) shows a dramatic break towards low Lx (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. Assuming both hard X-ray and [OIII] emission are fair indicators of AGN activity, it is important to understand this discrepancy. We present here the results of a mini-survey done with Swift on a selected sample of SDSS selected AGN. The objects have been sampled at different L([OIII]) to check the relation with the Lx observed with Swift.

  1. 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.

  2. The Study of Relativistic AGN Jets and Experimental Survey of AGN Properties

    NASA Astrophysics Data System (ADS)

    Sabzali, V.; Davoudifar, P.; Mickaelian, A. M.

    2016-09-01

    AGN, their evolution and their relativistic jets were studied on the basis of data from multi-wavelength surveys. NRAO VLA Sky Survey (NVSS) and VLBI were used to study radio jets and radio continuum emission of AGN. A population of AGN will be selected and used in a future optical survey for their jets.

  3. The radio luminosity function and redshift evolution of radio-mode and quasar-mode AGN

    NASA Astrophysics Data System (ADS)

    Pracy, Mike

    2016-08-01

    The properties of the AGN population indicate that there are two fundamentally different accretion modes operating. In the quasar-mode, material is accreted onto the supermassive black hole via a small, thin, optically luminous accretion disc. Accretion in this mode is recognisable by emission lines in the optical spectrum. However, there is a population of AGN observable only by their radio emission and without optical emission lines. These radio-mode AGN are likely powered by radiatively inefficient accretion from a hot gas halo. I will describe the cosmic evolution of these two populations via radio luminosity functions. The radio luminosity functions are constructed from a new survey of over 4000 radio galaxies out to z=1, all with confirmed redshifts and their accretion mode classified from their optical spectra. This is 20 times larger than the only other survey used to make such a measurement. The radio-mode AGN population displays no statistically significant evolution in space density out to redshift z=1. In contrast the quasar mode AGN exhibits rapid evolution in space density, increasing by a factor of 8 over the same redshift range. The characteristic break in the radio luminosity function occurs at a significantly higher power for the quasar-mode AGN in comparison to the radio-mode AGN and we demonstrate this is consistent with the two populations representing fundamentally different accretion modes. The radio luminosity function is used to estimate the total amount of mechanical energy available for radio mode feedback as a function of redshift, and is found to be in good agreement with cosmological models and previous measurements. Again, by separating by accretion mode, the previously estimated increase in available mechanical energy per unit volume out to z=1 (approximately a factor of 2) can be attributed to the rapid evolution of the quasar-mode AGN, while for the classical radio-mode AGN the total mechanical energy output remains roughly

  4. 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

  5. Decomposing de mid-infrared emission of AGN to study the disappearance of the torus at the low-luminosity end

    NASA Astrophysics Data System (ADS)

    Gomzález Martín, Omaira

    2016-08-01

    Low-luminosity active galactic nuclei (LLAGN) are key to understand the connection (perhaps evolutive) between normal and active galaxies. We have recently found that there are also key to study the connection between the AGN and its host. AGN at mid-infrared are dominated by the clumpy torus emission. However, this torus is expected to disappear below the bolometric luminosity of Lbol=10E+42 erg/s. We have analysed the obscuration of 40 LLAGN (with bolometric luminosities 10E+38 — 10E+43 erg/s) using Spitzer/IRS spectra. We have found for the first time that the torus signatures disappear below the predicted bolometric luminosity (González-Martín et al. 2015). However, this behaviour could also be explained by the preponderance of the host galaxy compared with a weak AGN. We have analysed if the torus has disappeared or diluted by the host emission by the decomposition of the Spitzer/IRS spectra. We have found (1) strong evidence in favor of the smooth vanishment of the torus and (2) an intrinsic difference on the molecular gas content on these objects where the torus is vanishing (Gonzalez-Martin et al. 2016, to be submitted). The implications of these results on the framework of the Unified Model will be discussed.

  6. Continuum and line emission in Cygnus A

    NASA Astrophysics Data System (ADS)

    Stockton, Alan; Ridgway, Susan E.; Lilly, Simon J.

    1994-08-01

    We present the results from (1) imaging observations of Cygnus A in five essentially line-free continuum bands with central wavelengths ranging from 0.34 to 2.1 microns. (2) imaging observations in five narrowband filters centered on the emission lines H beta(O III) lambda5007, H alpha(N II) lambda6583, and (S II) lambda lambda6716, 6731, and (3) deep spectroscopy covering the entire central region of Cyg A. We confirm that the featureless spectrum component is to be identified with the prominent double morphology at the center of Cyg A, but uncertainties in the distribution of the dust in this region tend to limit the accuracy with which we can determine its morphology and spectral-energy distribution (SED). From regions that appear to be least affected by obscuration, we find fv is approximately v-0.1 for this component. This SED could be consistent with free-free emission, a population of young stars, or a quasar continuum scattered by electrons, but probably not with a quasar continuum scattered by dust, which would be bluer. Our spectroscopy places an upper limit on the equivalent width of broad H beta that is well below that of typical quasars, showing that this flat-spectrum component (FSC) is almost certainly not dominated by scattered quasar radiation. Appeals to scattering by hot electrons to smear the scattered broad lines into invisibility appear to fail because the large density scale height of the electrons and the inefficiency of electron scattering should result in smoother and more extensive structure than we observe. Although the relative SED is consistent with free-free emission, the required amount of hot gas violates other observational constraints. At high angular resolution, the apparent morphology of the FSC is spiral-like. Although this impression may be partly due to obscuration, the distribution of the dust itself only serves to reinforce the spiral-like nature of the material with which it is associated. We conclude that the FSC is most

  7. 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).

  8. Herschel-ATLAS: the connection between star formation and AGN activity in radio-loud and radio-quiet active galaxies

    NASA Astrophysics Data System (ADS)

    Gürkan, G.; Hardcastle, M. J.; Jarvis, M. J.; Smith, D. J. B.; Bourne, N.; Dunne, L.; Maddox, S.; Ivison, R. J.; Fritz, J.

    2015-10-01

    We examine the relationship between star formation and active galactic nuclei (AGN) activity by constructing matched samples of local (0 < z < 0.6) radio-loud and radio-quiet AGN in the Herschel-Astrophysical Terahertz Large Area Survey fields. Radio-loud AGN are classified as high-excitation and low-excitation radio galaxies using their emission lines and WISE 22-μm luminosity. AGN accretion and jet powers in these active galaxies are traced by [O III] emission-line and radio luminosity, respectively. Star formation rates (SFRs) and specific star formation rates (SSFRs) were derived using Herschel 250-μm luminosity and stellar mass measurements from the Sloan Digital Sky Survey-Max Planck Institute for Astrophysics-John Hopkins University catalogue. In the past, star formation studies of AGN have mostly focused on high-redshift sources to observe the thermal dust emission that peaks in the far-infrared, which limited the samples to powerful objects. However, with Herschel we can expand this to low redshifts. Our stacking analyses show that SFRs and SSFRs of both radio-loud and radio-quiet AGN increase with increasing AGN power but that radio-loud AGN tend to have lower SFR. Additionally, radio-quiet AGN are found to have approximately an order of magnitude higher SSFRs than radio-loud AGN for a given level of AGN power. The difference between the star formation properties of radio-loud and -quiet AGN is also seen in samples matched in stellar mass.

  9. X-Ray Emission in Non-AGN Galaxies at z &8771 1

    NASA Astrophysics Data System (ADS)

    Chatterjee, Suchetana; Newman, Jeffrey A.; Jeltema, Tesla; Myers, Adam D.; Aird, James; Bundy, Kevin; Conselice, Christopher; Cooper, Michael; Laird, Elise; Nandra, Kirpal; Willmer, Christopher

    2015-06-01

    Using data from the DEEP2 galaxy redshift survey and the All Wavelength Extended Groth Strip International Survey we obtain stacked X-ray maps of galaxies at 0.7≤slant z≤slant 1.0 as a function of stellar mass. We compute the total X-ray counts of these galaxies and show that in the soft band (0.5-2 kev) there exists a significant correlation between galaxy X-ray counts and stellar mass at these redshifts. The best-fit relation between X-ray counts and stellar mass can be characterized by a power law with a slope of 0.58 ± 0.1. We do not find any correlation between stellar mass and X-ray luminosities in the hard (2-7 kev) and ultra-hard (4-7 kev) bands. The derived hardness ratios of our galaxies suggest that the X-ray emission is degenerate between two spectral models, namely point-like power-law emission and extended plasma emission in the interstellar medium. This is similar to what has been observed in low redshift galaxies. Using a simple spectral model where half of the emission comes from power-law sources and the other half from the extended hot halo we derive the X-ray luminosities of our galaxies. The soft X-ray luminosities of our galaxies lie in the range 1039-8× {{10}40} erg s-1. Dividing our galaxy sample by the criteria U-B\\gt 1, we find no evidence that our results for X-ray scaling relations depend on optical color.

  10. Atomic line emission analyzer for hydrogen isotopes

    DOEpatents

    Kronberg, J.W.

    1993-03-30

    Apparatus for isotopic analysis of hydrogen comprises a low pressure chamber into which a sample of hydrogen is introduced and then exposed to an electrical discharge to excite the electrons of the hydrogen atoms to higher energy states and thereby cause the emission of light on the return to lower energy states, a Fresnel prism made at least in part of a material anomalously dispersive to the wavelengths of interest for dispersing the emitted light, and a photodiode array for receiving the dispersed light. The light emitted by the sample is filtered to pass only the desired wavelengths, such as one of the lines of the Balmer series for hydrogen, the wavelengths of which differ slightly from one isotope to another. The output of the photodiode array is processed to determine the relative amounts of each isotope present in the sample. Additionally, the sample itself may be recovered using a metal hydride.

  11. Atomic line emission analyzer for hydrogen isotopes

    DOEpatents

    Kronberg, James W.

    1993-01-01

    Apparatus for isotopic analysis of hydrogen comprises a low pressure chamber into which a sample of hydrogen is introduced and then exposed to an electrical discharge to excite the electrons of the hydrogen atoms to higher energy states and thereby cause the emission of light on the return to lower energy states, a Fresnel prism made at least in part of a material anomalously dispersive to the wavelengths of interest for dispersing the emitted light, and a photodiode array for receiving the dispersed light. The light emitted by the sample is filtered to pass only the desired wavelengths, such as one of the lines of the Balmer series for hydrogen, the wavelengths of which differ slightly from one isotope to another. The output of the photodiode array is processed to determine the relative amounts of each isotope present in the sample. Additionally, the sample itself may be recovered using a metal hydride.

  12. Atomic line emission analyzer for hydrogen isotopes

    DOEpatents

    Kronberg, J.W.

    1991-05-08

    Apparatus for isotopic analysis of hydrogen comprises a low pressure chamber into which a sample of hydrogen is introduced and then exposed to an electrical discharge to excite the electrons of the hydrogen atoms to higher energy states and thereby cause the emission of light on the return to lower energy states, a Fresnel prism made at least in part of a material anomalously dispersive to the wavelengths of interest for dispersing the emitted light, and a photodiode array for receiving the dispersed light. The light emitted by the sample is filtered to pass only the desired wavelengths, such as one of the lines of the Balmer series for hydrogen, the wavelengths of which differ slightly from one isotope to another. The output of the photodiode array is processed to determine the relative amounts of each isotope present in the sample. Additionally, the sample itself may be recovered using, a metal hydride.

  13. On the accuracy of Black Hole Mass estimation from Broad Emission Lines

    NASA Astrophysics Data System (ADS)

    Mejia-Restrepo, Julian; Trakhtenbrot, Benny; Lira, Paulina; Netzer, Hagai; Capellupo, Daniel

    2016-08-01

    In this talk we compare single-epoch (SE) black hole mass (MBH) estimates based on low ionization (Hα, Hβ, and MgII) and high ionization (CIV) broad emission lines. We also examine the implications of different continuum modeling approaches in line width and MBH measurements. For this purpose we use a sample of 39 unobscured AGNs at z=1.55 selected to cover a large range in MBH (2.0dex) and L/Ledd (2.5dex) and observed by X-shooter. We find that using a local power-law continuum instead of a physically-motivated thin disk continuum leads to only slight underestimation of the FWHM of the lines and the associated MBH(FWHM). However, the line dispersion σ and associated MBH(σ) are strongly affected by the continuum placement providing less reliable mass estimates. We find that low ionization lines provides reliable virial MBH estimation. However, the CIV line is not reliable in the majority of the cases, indicating that the gas emitting this line may not be virialized. We find that Hα, Hβ show similar line widths and that FWHM(MgII) is about 30% narrower than FWHM(Hβ) . We test and confirm several recent suggestions to improve the accuracy in CIV-based mass estimates, relying on other UV emission lines. However, we find that such improvements do not help in reducing the scatter between CIV-based and Balmer-line-based mass estimates. This work has been recently accepted for publication in MNRAS.

  14. Radio continuum detection in blue early-type weak-emission-line galaxies

    NASA Astrophysics Data System (ADS)

    Paswan, A.; Omar, A.

    2016-06-01

    The star formation rates (SFRs) in weak-emission-line (WEL) galaxies in a volume-limited (0.02 < z < 0.05) sample of blue early-type galaxies (ETGs) identified from the Sloan Digital Sky Survey, are constrained here using 1.4-GHz radio continuum emission. The direct detection of 1.4-GHz radio continuum emission is made in eight WEL galaxies and a median stacking is performed on 57 WEL galaxies using Very Large Array (VLA) Faint Images of Radio Sky at Twenty-cm (FIRST) images. The median stacked 1.4-GHz flux density and luminosity are estimated as 79 ± 19 μJy and 0.20 ± 0.05 × 1021 W Hz-1, respectively. The radio far-infrared correlation in four WEL galaxies suggests that the radio continuum emission from WEL galaxies is most likely a result of star formation activities. The median SFR for WEL galaxies is estimated as 0.23 ± 0.06 M⊙ yr-1, which is much less than SFRs (0.5-50 M⊙ yr-1) in purely star-forming blue ETGs. The SFRs in blue ETGs are found to be correlated with their stellar velocity dispersions (σ) and decreasing gradually beyond σ of ˜100 km s-1. This effect is most likely linked to the growth of a black hole and the suppression of star formation via active galactic nucleus (AGN) feedback. The colour differences between star-forming and WEL subtypes of blue ETGs appear to be driven to a large extent by the level of current star formation activities. In a likely scenario of an evolutionary sequence between subtypes, the observed colour distribution in blue ETGs can be explained best in terms of fast evolution through AGN feedback.

  15. 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

  16. AGN torus emission for a homogeneous sample of bright flat-spectrum radio quasars

    NASA Astrophysics Data System (ADS)

    Castignani, G.; De Zotti, G.

    2015-01-01

    We have selected a complete sample of 80 flat-spectrum radio quasars (FSRQs) from the Wilkinson Microwave Anisotropy Probe (WMAP) seven-year catalog within the Sloan Digital Sky Survey (SDSS) area, all with measured redshift, and have inspected their spectral energy distributions (SEDs) looking for evidence of an active galactic nucleus torus emission. A SED fitting algorithm has found such evidence for seven objects and an uncertain indication for one more. A further analysis has picked out four additional FSRQs whose observed SEDs may be consistent with the presence of a torus. All 12 of these FSRQs belong to the subsample of 55 sources showing the optical-ultraviolet bump interpreted as thermal emission from a standard accretion disk. Torus luminosities have been estimated for the eight objects whose torus was identified by the fitting algorithm. For the other 47 FSRQs in the subsample, including the 4 with indications of torus emission not spotted by the algorithm, we have derived upper limits to the torus luminosity. Our analysis shows that the torus can show up clearly only under quite special conditions: low luminosity and preferentially low peak frequency of the beamed synchrotron emission from the jet; high torus luminosity, close to that of the accretion disk. This implies that the inferred ratios of torus to disk luminosity are biased high. The median value, considering upper limits as detections (survival analysis techniques are found to be inapplicable because of the excessive fraction of upper limits), is Ltorus/Ldisk ~ 1 while studies of radio quiet quasars yield average ratios ⟨ Ltorus/Ldisk ⟩ ≃ 1 / 3-1 / 2. On the other hand, although our poor statistics does not allow us to draw firm conclusions, our results are compatible with the FSRQ tori having the same properties as those of radio quiet quasars. At variance with another investigation of optically selected BL Lacs, we find that the Wide-field Infrared Survey Explorer (WISE) infrared

  17. Disentangling Dominance: Obscured AGN Activity versus Star Formation in BPT-Composites

    NASA Astrophysics Data System (ADS)

    Trouille, Laura

    2011-11-01

    Approximately 20% of SDSS emission-line galaxies (ELG) lie in the BPT-comp regime, between the Kauffmann et al. (2003) empirically determined SF-dominated regime and the Kewley et al. (2001) theoretically predicted AGN-dominated regime. BPT-AGN, on the other hand, make up only 11% of the ELG population. Whether to include the significant number of BPT-comp in samples of AGN or samples of star-forming galaxies is an open question and has important implications for galaxy evolution studies, metallicity studies, etc. Using a large pectroscopic sample of GOODS-N and LH galaxies with deep Chandra imaging, we perform an X-ray stacking analysis of BPT-comp. We find the stacked signal to be X-ray hard. This X-ray hardness can be indicative of obscured AGN activity or the presence of HMXBs associated with ongoing star formation. In order to distinguish between these scenarios, we perform an IR stacking analysis using Spitzer 24 micron data. The stacked BPT-comp lies well above the expected value for L_x/L_IR for pure star-forming galaxies; similarly for the X-ray detected BPT-comp. We also find that the BPT-comp lie in the AGN-dominated regime of our new TBT diagnostic, which uses [NeIII]/[OII] versus rest-frame g-z colour to identify AGN and star forming galaxies out to z=1.4. [NeIII], which has a higher ionisation potential than other commonly used forbidden emission lines, appears to foster a more reliable selection of AGN-dominated galaxies. These findings suggest that both the X-ray and optical signal in BPT-comp are dominated by obscured or low accretion rate AGN activity rather than star formation. This is in contrast to claims by previous optical emission-line studies that the signal in BPT-comp is dominated by star-formation activity. Therefore, we recommend that groups carefully consider the impact of excluding or including BPT-comp on the interpretation of their results. For example, for studies involving determining the bolometric contribution from AGN activity

  18. Still Raining in Quasars: An Origin for the Broad Emission Line Region

    NASA Astrophysics Data System (ADS)

    Elvis, Martin

    2016-01-01

    The strong broad emission lines (BELs) characteristic of quasars do not have an agreed-upon physical explanation. Why is there dense gas at hundreds to thousands of Schwarzchild radii around all* accreting super-massive black holes?I propose that dense cool clouds naturally form (Krolik et al. 1981) in the accretion disk winds of quasars and AGNs (Murray et al. 1995) before the wind reaches escape velocity. X-ray variability causes the gas to accumulate in the stable regions on the thermal equilibrium curve. These clouds have the density and temperature of BEL clouds. The narrow range of density at which the BEL clouds form in pressure equilibrium with the warm wind may explain the simple L1/2 scaling of BEL region radius. The clouds are self-shielding and can no longer accelerate; so they rain back on elliptical orbits. They are then destroyed by Kelvin-Helmholtz instabilities as they move at Mach ~ 30 through the warm disk wind. The timescales for all these processes fit with this picture.Observationally this "quasar rain" model agrees with the Pancoast et al. (2014) kinematics of the BEL region, with the cool phase of the warm absorber wind seen in X-rays (e.g. Krongold et al. 2005), and with the "cometary" tails seen in a few AGN X-ray eclipses (Maiolino et al. 2010).[* unobscured, non-jet-dominated.

  19. 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.

  20. Uncovering the Spectral Energy Distribution in Active Galaxies Using High Ionization Mid-Infrared Emission Lines

    NASA Technical Reports Server (NTRS)

    Melendez, M.; Kraemer, S. B.; Weaver, K. A.; Mushotzky, R. F.

    2011-01-01

    The shape of the spectral energy distribution of active galaxies in the EUV soft X-ray band (13.6 eV to 1 keV) is uncertain because obscuration by dust and gas can hamper our view of the continuum. To investigate the shape of the spectral energy distribution in this energy band, we have generated a set of photoionization models which reproduce the small dispersion found in correlations between high-ionization mid-infrared emission lines in a sample of hard X-ray selected AGN. Our calculations show that a broken power-law continuum model is sufficient to reproduce the [Ne V]14.32 microns/[Ne III], [Ne V]24.32 microns/[O IV]25.89 micron and [O IV] 25.89 microns/[Ne III] ratios, and does not require the addition of a "big bump" EUV model component. We constrain the EUV-soft X-ray slope, alpha(sub i), to be between 1.5 - 2.0 and derive a best fit of alpha(sub i) approx. 1.9 for Seyfert 1 galaxies, consistent with previous studies of intermediate redshift quasars. If we assume a blue bump model, most sources in our sample have derived temperatures between T(sub BB) = 10(exp 5.18) K to 10(exp 5.7) K, suggesting that the peak of this component spans a large range of energies extending from approx. (Lambda)600 A to > (Lambda)1900 A. In this case, the best fitting peak energy that matches the mid-infrared line ratios of Seyfert 1 galaxies occurs between approx. (Lambda)700-(Lambda)1000 A. Despite the fact that our results do not rule out the presence of an EUV bump, we conclude that our power-law model produces enough photons with energies > 4 Ry to generate the observed amount of mid-infrared emission in our sample of BAT AGN.

  1. Spectro-temporal diagnostics to evaluate physical structure around the AGN

    NASA Astrophysics Data System (ADS)

    Mizumoto, M.; Ebisawa, K.

    2016-06-01

    X-ray energy spectra from the AGN exhibit a lot of emission/absorption lines, which have been studied in detail by grating devices such as RGS on XMM-Newton. Variability of these spectral lines is considered to reflect physical conditions of the line emitting/absorbing matter. Thus, we study root-mean-square (RMS) spectra of several AGN observed with RGS to diagnose physical structures around these AGN. As a result, we have found clear peaks/dips in the RMS spectrum of NGC 4051, which can be modeled with variable absorption lines and non-variable emission lines. Several absorbers with different ionization states are required, where a lower-ionized (logξ=1.5) absorber shows larger variability and a higher-ionized (logξ=2.5) absorber shows little variability. These results directly give hints on physical structure around the AGN. We also show simulated RMS spectra of several AGN with Hitomi SXS, which is a more powerful diagnostic tool than RGS.

  2. 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.

  3. Semi-empirical AGN detection threshold in spectral synthesis studies of Lyman-continuum-leaking early-type galaxies

    NASA Astrophysics Data System (ADS)

    Cardoso, Leandro S. M.; Gomes, Jean-Michel; Papaderos, Polychronis

    2016-10-01

    Various lines of evidence suggest that the cores of a large portion of early-type galaxies (ETGs) are virtually evacuated of warm ionised gas. This implies that the Lyman-continuum (LyC) radiation produced by an assumed active galactic nucleus (AGN) can escape from the nuclei of these systems without being locally reprocessed into nebular emission, which would prevent their reliable spectroscopic classification as Seyfert galaxies with standard diagnostic emission-line ratios. The spectral energy distribution (SED) of these ETGs would then lack nebular emission and be essentially composed of an old stellar component and the featureless power-law (PL) continuum from the AGN. A question that arises in this context is whether the AGN component can be detected with current spectral population synthesis in the optical, specifically, whether these techniques effectively place an AGN detection threshold in LyC-leaking galaxies. To quantitatively address this question, we took a combined approach that involves spectral fitting with Starlight of synthetic SEDs composed of stellar emission that characterises a 10 Gyr old ETG and an AGN power-law component that contributes a fraction 0 ≤ xAGN < 1 of the monochromatic luminosity at λ0 = 4020 Å. In addition to a set of fits for PL distributions Fν ∝ ν- α with the canonical α = 1.5, we used a base of multiple PLs with 0.5 ≤ α ≤ 2 for a grid of synthetic SEDs with a signal-to-noise ratio of 5-103. Our analysis indicates an effective AGN detection threshold at xAGN ≃ 0.26, which suggests that a considerable fraction of ETGs hosting significant accretion-powered nuclear activity may be missing in the AGN demographics.

  4. 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.

  5. Physical conditions in the x-ray emission-line gas in the Seyfert 2 galaxy NGC 1068

    NASA Astrophysics Data System (ADS)

    Sharma, Neetika

    Active Galactic Nuclei (AGN) reside in the centers of many (10%) galaxies. The nuclear spectra exhibit a broad (from radio to gamma-rays) non-stellar continuum which exceeds the luminosity of the host. AGN are thought to be powered by accretion of matter onto a supermassive black hole (BH~10 6--109 times the mass of the Sun). Since this activity takes place in a relatively small region (<< 3 light years), the central engine of even the closest AGN cannot be imaged directly with current technology. Nevertheless, spectroscopic observations can help us constrain the conditions of the gas very close to the BH. The scientific goal of my thesis is to examine the physical conditions in the circumnuclear regions of the Seyfert 2 galaxy NGC 1068. The soft X-ray spectrum comprises a multitude of emission lines including those of C, N, O, Ne, Mg, that arise in gas that is spatially extended over ~1000 light years. Radiative recombination continuum widths indicate the gas is photoionized and I model it finding a two-zone solution with unusual abundances attributed to the star formation history of the galaxy. Also of interest are the Fe K complex of em.

  6. Spatially-Resolved HST GRISM Spectroscopy of a Lensed Emission Line Galaxy at Z to approximately 1

    NASA Technical Reports Server (NTRS)

    Frye, Brenda L.; Hurley, Mairead; Bowen, David V.; Meurer, Gerhardt; Sharon, Keren; Straughn, Amber; Coe, Dan; Broadhurst, Tom; Guhathakurta, Puragra

    2012-01-01

    We take advantage of gravitational lensing amplification by Abell 1689 (z=0.187) to undertake the first space-based census of emission line galaxies (ELGs) in the field of a massive lensing cluster. Forty-three ELGs are identified to a flux of i(sub 775)=27.3 via slitless grism spectroscopy. One ELG (at z=0.7895) is very bright owing to lensing magnification by a factor of approx = 4.5. Several Balmer emission lines detected from ground-based follow-up spectroscopy signal the onset of a major starburst for this low-mass galaxy (M(sub star) approx = 2 x 10(exp 9)Solar Mass) with a high specific star formation rate (approx = 20/ Gyr). From the blue emission lines we measure a gas-phase oxygen abundance consistent with solar (12+log(O /H)=8.8 +/- O.2). We break the continuous line-emitting region of this giant arc into seven approx 1 kpc bins (intrinsic size) and measure a variety of metallicity dependent line ratios. A weak trend of increasing metal fraction is seen toward the dynamical center of the galaxy. Interestingly, the metal line ratios in a region offset from the center by -lkpc have a placement on the blue HI! region excitation diagram with f([OIII]/ f(H-Beta) and f([NeIII/ f(H-Beta) that can be fit by an AGN. This asymmetrical AGN-like behavior is interpreted as a product of shocks in the direction of the galaxy's extended tail, possibly instigated by a recent galaxy interaction.

  7. Evidence for Ultra-Fast Outflows in Radio-Quiet AGNs. 2; Detailed Photoionization Modeling of Fe K-Shell Absorption Lines

    NASA Technical Reports Server (NTRS)

    Tombesi, Francesco; Clapp, M.; Reeves, J. N.; Palumbo, G. G. C.; Braito, V.; Dadina, M.

    2011-01-01

    X-ray absorption line spectroscopy has recently shown evidence for previously unknown Ultra-fast Outflows (UFOs) in radio-quiet AGNs. In the previous paper of this series we defined UFOs as those absorbers with an outflow velocity higher than 10,000km/s and assessed the statistical significance of the associated blue shifted FeK absorption lines in a large sample of 42 local radio-quiet AGNs observed with XMM-Newton. In the present paper we report a detailed curve of growth analysis and directly model the FeK absorbers with the Xstar photo-ionization code. We confirm that the frequency of sources in the radio-quiet sample showing UFOs is >35%. The outflow velocity distribution spans from \\sim10,000km/s (\\sim0.03c) up to \\siml00,000kmis (\\sim0.3c), with a peak and mean value of\\sim42,000km/s (\\sim0.14c). The ionization parameter is very high and in the range log\\xi 3-6 erg s/cm, with a mean value of log\\xi 4.2 erg s/cm. The associated column densities are also large, in the range N_H\\siml0(exp 22)-10(exp 24)/sq cm, with a mean value of N_H\\siml0(exp23)/sq cm. We discuss and estimate how selection effects, such as those related to the limited instrumental sensitivity at energies above 7keV, may hamper the detection of even higher velocities and higher ionization absorbers. We argue that, overall, these results point to the presence of extremely ionized and possibly almost Compton thick outflowing material in the innermost regions of AGNs. This also suggests that UFOs may potentially play a significant role in the expected cosmological feedback from AGNs and their study can provide important clues on the connection between accretion disks, winds and jets.

  8. Star-Formation in Low Radio Luminosity AGN from the Sloan Digital Sky Survey

    SciTech Connect

    de Vries, W H; Hodge, J A; Becker, R H; White, R L; Helfand, D J

    2007-04-18

    We investigate faint radio emission from low- to high-luminosity Active Galactic Nuclei (AGN) selected from the Sloan Digital Sky Survey (SDSS). Their radio properties are inferred by coadding large ensembles of radio image cut-outs from the FIRST survey, as almost all of the sources are individually undetected. We correlate the median radio flux densities against a range of other sample properties, including median values for redshift, [O III] luminosity, emission line ratios, and the strength of the 4000{angstrom} break. We detect a strong trend for sources that are actively undergoing star-formation to have excess radio emission beyond the {approx} 10{sup 28} ergs s{sup -1} Hz{sup -1} level found for sources without any discernible star-formation. Furthermore, this additional radio emission correlates well with the strength of the 4000{angstrom} break in the optical spectrum, and may be used to assess the age of the star-forming component. We examine two subsamples, one containing the systems with emission line ratios most like star-forming systems, and one with the sources that have characteristic AGN ratios. This division also separates the mechanism responsible for the radio emission (star-formation vs. AGN). For both cases we find a strong, almost identical, correlation between [O III] and radio luminosity, with the AGN sample extending toward lower, and the star-formation sample toward higher luminosities. A clearer separation between the two subsamples is seen as function of the central velocity dispersion {sigma} of the host galaxy. For systems at similar redshifts and values of {sigma}, the star-formation subsample is brighter than the AGN in the radio by an order of magnitude. This underlines the notion that the radio emission in star-forming systems can dominate the emission associated with the AGN.

  9. 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.

  10. X-Rays and Infrared Selected AGN

    NASA Astrophysics Data System (ADS)

    Kirhakos, S. D.; Steiner, J. E.

    1990-11-01

    RESUMEN. En la busqueda de nucleos activos galacticos (NAG) oscurecidos, seleccionamos una tnuestra de galaxias ernisoras de rayos S infrarrojos, Ia mayoria de las cuales son vistas de perf ii. La 6ptica de la regi6n nuclear de las galaxias seleccionadas revelan que el 76% de ellas muestran lineas de emisi5n La clasificaci6n de los es- pectros de acuerdo a los anchos y a la intensidad de cocientes de lineas muestran que existen 34 NAG, 34 objetos de tipo de transici6n y 34 galaxias de la regi6n con nucleos de tipo regi6n H II. Entre los NAG, 3 son del tipo Seyfert I y las otras son del tipo 2. Sugerimos que los objetos identificados como NAG de llneas angostas son objetos tipo Seyfert I oscurecidos ABSTRACT. Looking for obscured active galactic nuclei (AGN), we selected a sample of infrarediX-rays emitting galaxies, mos"t of which are seen as edge-on. Optical spectroscopy of the nuclear region of the selected galaxies revealed that 76 % of them show emission l 'nes. Classification of the spectra according to the widths and line intensity ratios shows that there are 34 AGN, 34 transition type objects and 43 nuclear HIl-like region galaxies. Among the AGN, three are Seyfert type 1 and the others are type 2 objects. We suggest that the objects identified as narrow line AGN are obscured Seyfert 1. o'L : GALAXIES-ACTIVE - X-RAY S-GENERAL

  11. Testing different AGN tracers on a local sample of Seyfert galaxies

    NASA Astrophysics Data System (ADS)

    Pozzi, F.

    2016-08-01

    I will present our new study on a local sample of Seyfert galaxies selected at 12 micron. This sample, given its plenty of information, both photometric and spectroscopic, is a perfect sample to compare, from a statistical point of view, different AGN selection criteria, and AGN derived intrinsic properties. In detail, I will compare AGN activity derived from SED-fitting technique, X-ray luminosity and AGN activity traced by high excitation IR lines, like [NeV] and [OIV]. Moreover, for one particular obscured X-ray Compton-thick source, thanks also to the availability of ALMA data, I will derive a self-consistent overview of the physics behind the emission in different bands,by taking advantage of the photoionization code CLOUDY.

  12. X-Ray Emission from Active Galactic Nuclei with Intermediate-Mass Black Holes

    NASA Astrophysics Data System (ADS)

    Dewangan, G. C.; Mathur, S.; Griffiths, R. E.; Rao, A. R.

    2008-12-01

    We present a systematic X-ray study of eight active galactic nuclei (AGNs) with intermediate-mass black holes (MBH ~ 8-95 × 104 M⊙) based on 12 XMM-Newton observations. The sample includes the two prototype AGNs in this class—NGC 4395 and POX 52 and six other AGNs discovered with the Sloan Digitized Sky Survey. These AGNs show some of the strongest X-ray variability, with the normalized excess variances being the largest and the power density break timescales being the shortest observed among radio-quiet AGNs. The excess-variance-luminosity correlation appears to depend on both the BH mass and the Eddington luminosity ratio. The break timescale-black hole mass relations for AGN with IMBHs are consistent with that observed for massive AGNs. We find that the FWHM of the Hβ/Hα line is uncorrelated with the BH mass, but shows strong anticorrelation with the Eddington luminosity ratio. Four AGNs show clear evidence for soft X-ray excess emission (kTin ~ 150-200 eV). X-ray spectra of three other AGNs are consistent with the presence of the soft excess emission. NGC 4395 with lowest L/LEdd lacks the soft excess emission. Evidently small black mass is not the primary driver of strong soft X-ray excess emission from AGNs. The X-ray spectral properties and optical-to-X-ray spectral energy distributions of these AGNs are similar to those of Seyfert 1 galaxies. The observed X-ray/UV properties of AGNs with IMBHs are consistent with these AGNs being low-mass extensions of more massive AGNs, those with high Eddington luminosity ratio looking more like narrow-line Seyfert 1 s and those with low L/LEdd looking more like broad-line Seyfert 1 galaxies.

  13. 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".

  14. HST Imaging of Giant Ionized Clouds Around Fading AGN

    NASA Astrophysics Data System (ADS)

    Keel, William C.; Maksym, W. P.; Bennert, V.; Schawinski, K.; Lintott, C. J.; Chojnowski, D.

    2013-01-01

    We present HST images in [O III], Hα, and adjacent continuum bands, for 7 AGN surrounding by photoionized clouds extending 10-35 kpc from the nuclei, whose energy budgets suggest substantial fading over timescales 30,000-100,000 years. These targets were found as a result of the efforts of nearly 200 Galaxy Zoo volunteers in both targeted and serendipitous searches, aimed at finding objects similar to Hanny's Voorwerp near IC 2497. The images reveal a fascinating variety of emission-line structures. Sub-kpc loops near the nuclei are frequent. A larger 5-kpc ring of emission appears near one AGN, not obviously connected to the gas near the nucleus. In NGC 5972, two systems of gas and dust appear, in a pattern suggesting that they result from a merger; there is a gap in line emission around the nucleus which would fit with a rapid cutoff in ionizing luminosity. Some of these clouds have their emission concentrated in very narrow filaments kiloparsecs in length, which might suggest a role for extensive magnetic fields. As in Hanny's Voorwerp, we see little spatial correlation between ionization parameter and Hα surface brightness, indicating that there is substantial density structure on yet-unresolved scales. The two AGN with large double radio sources show extended line emission perpendicular to the radio axis, violating a common pattern, as if the AGN axis had recently and rapidly precessed by ~90 degrees. This, plus the common signs of recent interaction in the hosts, informs our speculations on what might drive a rapid switch in the mode of energy output from accretion into the black holes in these objects, from radiative to kinetic, including the possibility that a special epoch near the merger of a binary black hole might be involved. This work has been supported by NASA through STSCI grant GO-12525.01.

  15. 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.

  16. ITERA: IDL Tool for Emission-line Ratio Analysis

    NASA Astrophysics Data System (ADS)

    Groves, Brent; Allen, Mark

    2013-07-01

    ITERA, the IDL Tool for Emission-line Ratio Analysis, is an IDL widget tool that allows you to plot ratios of any strong atomic and ionized emission lines as determined by standard photoionization and shock models. These "line ratio diagrams" can then be used to determine diagnostics for nebulae excitation mechanisms or nebulae parameters such as density, temperature, metallicity, etc. ITERA can also be used to determine line sensitivities to such parameters, compare observations with the models, or even estimate unobserved line fluxes.

  17. CO J = 2-1 Line Emission in Cluster Galaxies at z ~ 1: Fueling Star Formation in Dense Environments

    NASA Astrophysics Data System (ADS)

    Wagg, Jeff; Pope, Alexandra; Alberts, Stacey; Armus, Lee; Brodwin, Mark; Bussmann, Robert S.; Desai, Vandana; Dey, Arjun; Jannuzi, Buell; Le Floc'h, Emeric; Melbourne, Jason; Stern, Daniel

    2012-06-01

    We present observations of CO J = 2-1 line emission in infrared-luminous cluster galaxies at z ~ 1 using the IRAM Plateau de Bure Interferometer. Our two primary targets are optically faint, dust-obscured galaxies (DOGs) found to lie within 2 Mpc of the centers of two massive (>1014 M ⊙) galaxy clusters. CO line emission is not detected in either DOG. We calculate 3σ upper limits to the CO J = 2-1 line luminosities, L'CO < 6.08 × 109 and <6.63 × 109 K km s-1 pc2. Assuming a CO-to-H2 conversion factor derived for ultraluminous infrared galaxies in the local universe, this translates to limits on the cold molecular gas mass of M_H_2 < 4.86 \\times 10^{9} \\,M_{\\odot } and M_H_2 < 5.30 \\times 10^{9} \\,M_{\\odot }. Both DOGs exhibit mid-infrared continuum emission that follows a power law, suggesting that an active galactic nucleus (AGN) contributes to the dust heating. As such, estimates of the star formation efficiencies in these DOGs are uncertain. A third cluster member with an infrared luminosity, L IR < 7.4 × 1011 L ⊙, is serendipitously detected in CO J = 2-1 line emission in the field of one of the DOGs located roughly two virial radii away from the cluster center. The optical spectrum of this object suggests that it is likely an obscured AGN, and the measured CO line luminosity is L'CO = (1.94 ± 0.35) × 1010 K km s-1 pc2, which leads to an estimated cold molecular gas mass M_H_2 = (1.55 +/- 0.28)\\times 10^{10}\\,M_{\\odot }. A significant reservoir of molecular gas in a z ~ 1 galaxy located away from the cluster center demonstrates that the fuel can exist to drive an increase in star formation and AGN activity at the outskirts of high-redshift clusters. Based on observations carried out with the IRAM Plateau de Bure Interferometer. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain).

  18. CO J = 2-1 LINE EMISSION IN CLUSTER GALAXIES AT z {approx} 1: FUELING STAR FORMATION IN DENSE ENVIRONMENTS

    SciTech Connect

    Wagg, Jeff; Pope, Alexandra; Alberts, Stacey; Armus, Lee; Desai, Vandana; Brodwin, Mark; Bussmann, Robert S.; Dey, Arjun; Jannuzi, Buell; Le Floc'h, Emeric; Melbourne, Jason; Stern, Daniel

    2012-06-20

    We present observations of CO J = 2-1 line emission in infrared-luminous cluster galaxies at z {approx} 1 using the IRAM Plateau de Bure Interferometer. Our two primary targets are optically faint, dust-obscured galaxies (DOGs) found to lie within 2 Mpc of the centers of two massive (>10{sup 14} M{sub Sun }) galaxy clusters. CO line emission is not detected in either DOG. We calculate 3{sigma} upper limits to the CO J = 2-1 line luminosities, L'{sub CO} < 6.08 Multiplication-Sign 10{sup 9} and <6.63 Multiplication-Sign 10{sup 9} K km s{sup -1} pc{sup 2}. Assuming a CO-to-H{sub 2} conversion factor derived for ultraluminous infrared galaxies in the local universe, this translates to limits on the cold molecular gas mass of M{sub H{sub 2}}< 4.86 Multiplication-Sign 10{sup 9} M{sub Sun} and M{sub H{sub 2}}< 5.30 Multiplication-Sign 10{sup 9} M{sub Sun }. Both DOGs exhibit mid-infrared continuum emission that follows a power law, suggesting that an active galactic nucleus (AGN) contributes to the dust heating. As such, estimates of the star formation efficiencies in these DOGs are uncertain. A third cluster member with an infrared luminosity, L{sub IR} < 7.4 Multiplication-Sign 10{sup 11} L{sub Sun }, is serendipitously detected in CO J = 2-1 line emission in the field of one of the DOGs located roughly two virial radii away from the cluster center. The optical spectrum of this object suggests that it is likely an obscured AGN, and the measured CO line luminosity is L'{sub CO} = (1.94 {+-} 0.35) Multiplication-Sign 10{sup 10} K km s{sup -1} pc{sup 2}, which leads to an estimated cold molecular gas mass M{sub H{sub 2}}= (1.55{+-}0.28) Multiplication-Sign 10{sup 10} M{sub Sun }. A significant reservoir of molecular gas in a z {approx} 1 galaxy located away from the cluster center demonstrates that the fuel can exist to drive an increase in star formation and AGN activity at the outskirts of high-redshift clusters.

  19. Optical emission line monitor with background observation and cancellation

    DOEpatents

    Goff, D.R.; Notestein, J.E.

    1985-01-04

    A fiber optics based optical emission line monitoring system is provided in which selected spectral emission lines, such as the sodium D-line emission in coal combustion, may be detected in the presence of interferring background or blackbody radiation with emissions much greater in intensity than that of the emission line being detected. A bifurcated fiber optic light guide is adapted at the end of one branch to view the combustion light which is guided to a first bandpass filter, adapted to the common trunk end of the fiber. A portion of the light is reflected back through the common trunk portion of the fiber to a second bandpass filter adapted to the end of the other branch of the fiber. The first filter bandpass is centered at a wavelength corresponding to the emission line to be detected with a bandwidth of about three nanometers (nm). The second filter is centered at the same wavelength but having a width of about 10 nm. First and second light detectors are located to view the light passing through the first and second filters respectively. Thus, the second detector is blind to the light corresponding to the emission line of interest detected by the first detector and the difference between the two detector outputs is uniquely indicative of the intensity of only the combustion flame emission of interest. This instrument can reduce the effects of interfering blackbody radiation by greater than 20 dB.

  20. Optical emission line monitor with background observation and cancellation

    DOEpatents

    Goff, David R.; Notestein, John E.

    1986-01-01

    A fiber optics based optical emission line monitoring system is provided in which selected spectral emission lines, such as the sodium D-line emission in coal combustion, may be detected in the presence of interferring background or blackbody radiation with emissions much greater in intensity than that of the emission line being detected. A bifurcated fiber optic light guide is adapted at the end of one branch to view the combustion light which is guided to a first bandpass filter, adapted to the common trunk end of the fiber. A portion of the light is reflected back through the common trunk portion of the fiber to a second bandpass filter adapted to the end of the other branch of the fiber. The first filter bandpass is centered at a wavelength corresponding to the emission line to be detected with a bandwidth of about three nanometers (nm). The second filter is centered at the same wavelength but having a width of about 10 nm. First and second light detectors are located to view the light passing through the first and second filters respectively. Thus, the second detector is blind to the light corresponding to the emission line of interest detected by the first detector and the difference between the two detector outputs is uniquely indicative of the intensity of only the combustion flame emission of interest. This instrument can reduce the effects of interferring blackbody radiation by greater than 20 dB.

  1. Spectroscopy of unusual emission-line stars

    NASA Technical Reports Server (NTRS)

    Bopp, Bernard W.

    1988-01-01

    New spectroscopic observations are reported for ten stars that have been identified in the literature as having H-alpha emission with suspected F, G, or K spectral types. Three of the stars are shown to be BE stars, two are confirmed as early-type supergiants, three show composite (F or K + B) spectra, one is a 'post-T Tauri' star, and one is an ordinary F star without emission.

  2. Absorbing Outflows in AGN

    NASA Technical Reports Server (NTRS)

    Mathur, Smita

    2002-01-01

    The goal of this program was a comprehensive multiwavelength study of absorption phenomena in active galactic nuclei (AGN). These include a variety of associated absorption systems: X-ray warm absorbers, X-ray cold absorbers. UV absorbers with high ionization lines, MgII absorbers, red quasars and BALQSOs. The aim is to determine the physical conditions in the absorbing outflows, study their inter-relations and their role in AGN. We designed several observing programs to achieve this goal: X-ray spectroscopy, UV spectroscopy, FLAY spectroscopy and X-ray imaging. We were very successful towards achieving the goal over the five year period as shown through following observing programs and papers. Copies of a few papers are attached with this report.

  3. Search for cosmological emission lines - A new method

    SciTech Connect

    De Bernardis, P.; Masi, S.; Melchiorri, B.; Melchiorri, F. )

    1990-07-01

    The spectrum of the dipole anisotropy of the line emission, caused by the motion of earth with respect to the cosmological lines emitted by distant matter, is studied. Examples of both the line emission intensity and the dipole spectra are presented. It is shown that this differential method efficiently extracts the line signal from the local background, thus providing a new cosmological observational tool. This method can be used in the satellite infrared spectrometers which will be flown in the next 10 yr (ISO, COBE, etc). 13 refs.

  4. 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⊙.

  5. THE SOFT X-RAY AND NARROW-LINE EMISSION OF Mrk 573 ON KILOPARSEC SCALES

    SciTech Connect

    Gonzalez-Martin, O.; Acosta-Pulido, J. A.; Garcia, A. M. Perez

    2010-11-10

    We present a study of the circumnuclear region of the nearby Seyfert galaxy Mrk 573 using Chandra, XMM-Newton, and Hubble Space Telescope (HST) data. We have studied the morphology of the soft (<2 keV) X-rays comparing it with the [O III] and H{alpha} HST images. The soft X-ray emission is resolved into a complex extended region. The X-ray morphology shows a biconical region extending up to 12 arcsec (4 kpc) in projection from the nucleus. A strong correlation between the X-rays and the highly ionized gas seen in the [O III]{lambda}5007 A image is reported. Moreover, we have studied the line intensities detected with the XMM-Newton Reflection Grating Spectrometer (RGS) and used them to fit the low-resolution EPIC/XMM-Newton and ACIS/Chandra spectra. The RGS/XMM-Newton spectrum is dominated by emission lines of C VI, O VII, O VIII, Fe XVII, and Ne IX, among other highly ionized species. A good fit is obtained using these emission lines found in the RGS/XMM-Newton spectrum as a template for Chandra spectra of the nucleus and extended emission, coincident with the cone-like structures seen in the [O III]/H{alpha} map. The photoionization model Cloudy provides a reasonable fit for both the nuclear region and the cone-like structures showing that the dominant excitation mechanism is photoionization. For the nucleus the emission is modeled using two phases: a high ionization [log (U) = 1.23] and a low ionization [log (U) = 0.13]. For the high-ionization phase the transmitted and reflected components are in a 1:2 ratio, whereas for the low ionization the reflected component dominates. For the extended emission, we successfully reproduced the emission with two phases. The first phase shows a higher ionization parameter for the northwest (log (U) = 0.9) than for the southeast cone (log (U) = 0.3). Moreover, this phase is transmission dominated for the southeast cone and reflection dominated for the northwest cone. The second phase shows a low-ionization parameter (log (U

  6. AGN feedback in the nucleus of M 51

    NASA Astrophysics Data System (ADS)

    Querejeta, M.; Schinnerer, E.; García-Burillo, S.; Bigiel, F.; Blanc, G. A.; Colombo, D.; Hughes, A.; Kreckel, K.; Leroy, A. K.; Meidt, S. E.; Meier, D. S.; Pety, J.; Sliwa, K.

    2016-10-01

    AGN feedback is invoked as one of the most relevant mechanisms that shape the evolution of galaxies. Our goal is to understand the interplay between AGN feedback and the interstellar medium in M 51, a nearby spiral galaxy with a modest AGN and a kpc-scale radio jet expanding through the disc of the galaxy. For this purpose, we combine molecular gas observations in the CO(1-0) and HCN(1-0) lines from the Plateau de Bure interferometer with archival radio, X-ray, and optical data. We show that there is a significant scarcity of CO emission in the ionisation cone, while molecular gas emission tends to accumulate towards the edges of the cone. The distribution and kinematics of CO and HCN line emission reveal AGN feedback effects out to r ~ 500 pc, covering the whole extent of the radio jet, with complex kinematics in the molecular gas which displays strong local variations. We propose that this is the result of the almost coplanar jet pushing on molecular gas in different directions as it expands; the effects are more pronounced in HCN than in CO emission, probably as the result of radiative shocks. Following previous interpretation of the redshifted molecular line in the central 5'' as caused by a molecular outflow, we estimate the outflow rates to be ṀH2 ~ 0.9 M⊙/ yr and Ṁdense ~ 0.6 M⊙/ yr, which are comparable to the molecular inflow rates (~1 M⊙/ yr); gas inflow and AGN feedback could be mutually regulated processes. The agreement with findings in other nearby radio galaxies suggests that this is not an isolated case, and is probably the paradigm of AGN feedback through radio jets, at least for galaxies hosting low-luminosity active nuclei. The reduced HCN(1-0) datacube is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/593/A118

  7. Disentangling AGN and Star Formation Activity at High Redshift Using Hubble Space Telescope Grism Spectroscopy

    NASA Astrophysics Data System (ADS)

    Bridge, Joanna S.; Zeimann, Gregory R.; Trump, Jonathan R.; Gronwall, Caryl; Ciardullo, Robin; Fox, Derek; Schneider, Donald P.

    2016-08-01

    Differentiating between active galactic nucleus (AGN) activity and star formation in z ˜ 2 galaxies is difficult because traditional methods, such as line-ratio diagnostics, change with redshift, while multi-wavelength methods (X-ray, radio, IR) are sensitive to only the brightest AGNs. We have developed a new method for spatially resolving emission lines using the Hubble Space Telescope/Wide Field Camera 3 G141 grism spectra and quantifying AGN activity through the spatial gradient of the [O iii]/Hβ line ratio. Through detailed simulations, we show that our novel line-ratio gradient approach identifies ˜40% more low-mass and obscured AGNs than obtained by classical methods. Based on our simulations, we developed a relationship that maps the stellar mass, star formation rate, and measured [O iii]/Hβ gradient to the AGN Eddington ratio. We apply our technique to previously studied stacked samples of galaxies at z ˜ 2 and find that our results are consistent with these studies. This gradient method will also be able to inform other areas of galaxy evolution science, such as inside-out quenching and metallicity gradients, and will be widely applicable to future spatially resolved James Webb Space Telescope data.

  8. Line Emission from Optically Thick RelativisticAccretion Tori

    SciTech Connect

    Fuerst, Steven V.; Wu, Kinwah; /Mullard Space Sci. Lab.

    2007-09-14

    We calculate line emission from relativistic accretion tori around Kerr black holes and investigate how the line profiles depend on the viewing inclination, spin of the central black hole, parameters describing the shape of the tori, and spatial distribution of line emissivity on the torus surface. We also compare the lines with those from thin accretion disks. Our calculations show that lines from tori and lines from thin disks share several common features. In particular, at low and moderate viewing inclination angles they both have asymmetric double-peaked profiles with a tall, sharp blue peak and a shorter red peak which has an extensive red wing. At high viewing inclination angles they both have very broad, asymmetric lines which can be roughly considered as single-peaked. Torus and disk lines may show very different red and blue line wings, but the differences are due to the models for relativistic tori and disks having differing inner boundary radii. Self-eclipse and lensing play some role in shaping the torus lines, but they are effective only at high inclination angles. If inner and outer radii of an accretion torus are the same as those of an accretion disk, their line profiles show substantial differences only when inclination angles are close to 90{sup o}, and those differences are manifested mostly at the central regions of the lines instead of the wings.

  9. Significant contribution of the Cerenkov line-like radiation to the broad emission lines of quasars

    SciTech Connect

    Liu, D. B.; You, J. H.; Chen, W. P.; Chen, L. E-mail: dliu@cfa.Harvard.edu

    2014-01-01

    The Cerenkov line-like radiation in a dense gas (N {sub H} > 10{sup 13} cm{sup –3}) is potentially important in the exploration of the optical broad emission lines of quasars and Seyfert 1 galaxies. With this quasi-line emission mechanism, some long standing puzzles in the study of quasars could be resolved. In this paper, we calculate the power of the Cerenkov line-like radiation in dense gas and compare with the powers of other radiation mechanisms by a fast electron to confirm its importance. From the observed gamma-ray luminosity of 3C 279, we show that the total number of fast electrons is sufficiently high to allow effective operation of the quasi-line emission. We present a model calculation for the luminosity of the Cerenkov Lyα line of 3C 279, which is high enough to compare with observations. We therefore conclude that the broad line of quasars may be a blend of the Cerenkov emission line with the real line produced by the bound-bound transition. A new approach to the absorption of the Cerenkov line is presented with the method of escape probability, which markedly simplifies the computation in the optically thick case. The revised set of formulae for the Cerenkov line-like radiation is more convenient in applications.

  10. An infrared and optical analysis of a sample of XBONGs and optically elusive AGNs

    SciTech Connect

    Smith, K. L.; Mushotzky, R. F.; Koss, M. E-mail: richard@astro.umd.edu

    2014-10-20

    We present near-infrared (NIR) spectra of four optically elusive active galactic nuclei (AGNs) and four X-ray bright, optically normal galaxies (XBONGs) from the Swift-BAT survey. With archival observations from the Sloan Digital Sky Survey, the Two Micron All Sky Survey, Spitzer, and the Wide-field Infrared Survey Explorer (WISE), we test a number of AGN indicators in the NIR and mid-infrared; namely, NIR emission line diagnostic ratios, the presence of coronal high-ionization lines, and infrared photometry. Of our eight hard X-ray selected AGNs, we find that optical normalcy has a variety of causes from object to object, and no one explanation applies. Our objects have normal Eddington ratios and so are unlikely to host radiatively inefficient accretion flows. It is unlikely that star formation in the host or starlight dilution is contributing to their failure of optical diagnostics, except perhaps in two cases. The NIR continua are well fit by two blackbodies: one at the stellar temperature, and a hot dust component near the dust sublimation temperature. The XBONGs are more likely to have significant hot dust components, while these components are small relative to starlight in the optically elusive AGN. Some of our sample have NIR line ratios typical of AGNs, but NIR diagnostics are unsuccessful in distinguishing H II regions from AGNs in general. In one object, we discover a hidden broad-line region in the NIR. These results have strong relevance to the origin of optically normal AGNs in deep X-ray surveys.

  11. QSO emission line profiles from Keplerian cloud ensembles

    NASA Technical Reports Server (NTRS)

    Bradley, S. E.; Puetter, R. C.

    1986-01-01

    Quasar broad emission line profile calculations are presented for spherically symmetric ensembles of flattened broad-line clouds in elliptical Keplerian orbits. In general, it is found that high eccentricity monoenergetic orbital ensembles tend to provide more acceptable profiles than low eccentricity monoenergetic ensembles. The investigation of elliptical cloud orbits evolving under the influence of Poynting-Robertson drag or drag from an intercloud media shows that acceptable line profiles naturally result from the decay of initially monoenergetic, high eccentricity ensembles independent of the assumed emission anisotropy, provided the drag is not so great as to cause the immediate capture or disruption of the clouds.

  12. Helium shells and faint emission lines from slitless flash spectra.

    PubMed

    Bazin, Cyril; Koutchmy, Serge

    2013-05-01

    At the time of the two last solar total eclipses of August 1st, 2008 in Siberia and July 11th, 2010 in French Polynesia, high frame rate CCD flash spectra were obtained. These eclipses occurred in quiet Sun period and after. The slitless flash spectra show two helium shells, in the weak Paschen α 4686 Å line of the ionized helium HeII and in the neutral helium HeI line at 4713 Å. The extensions of these helium shells are typically 3 Mm. In prominences, the extension of the interface with the corona is much more extended. The observations and analysis of these lines can properly be done only in eclipse conditions, when the intensity threshold reaches the coronal level, and the parasitic scattered light is virtually zero. Under the layers of 1 Mm above the limb, many faint low FIP lines were also seen in emission. These emission lines are superposed on the continuum containing absorption lines. The solar limb can be defined using the weak continuum appearing between the emission lines at the time of the second and third contact. The variations of the singly ionized iron line, the HeI and HeII lines and the continuum intensity are analyzed. The intensity ratio of ionized to neutral helium is studied for evaluating the ionization rate in low layers up to 2 Mm and also around a prominence. PMID:25685435

  13. Helium shells and faint emission lines from slitless flash spectra

    PubMed Central

    Bazin, Cyril; Koutchmy, Serge

    2013-01-01

    At the time of the two last solar total eclipses of August 1st, 2008 in Siberia and July 11th, 2010 in French Polynesia, high frame rate CCD flash spectra were obtained. These eclipses occurred in quiet Sun period and after. The slitless flash spectra show two helium shells, in the weak Paschen α 4686 Å line of the ionized helium HeII and in the neutral helium HeI line at 4713 Å. The extensions of these helium shells are typically 3 Mm. In prominences, the extension of the interface with the corona is much more extended. The observations and analysis of these lines can properly be done only in eclipse conditions, when the intensity threshold reaches the coronal level, and the parasitic scattered light is virtually zero. Under the layers of 1 Mm above the limb, many faint low FIP lines were also seen in emission. These emission lines are superposed on the continuum containing absorption lines. The solar limb can be defined using the weak continuum appearing between the emission lines at the time of the second and third contact. The variations of the singly ionized iron line, the HeI and HeII lines and the continuum intensity are analyzed. The intensity ratio of ionized to neutral helium is studied for evaluating the ionization rate in low layers up to 2 Mm and also around a prominence. PMID:25685435

  14. Helium shells and faint emission lines from slitless flash spectra.

    PubMed

    Bazin, Cyril; Koutchmy, Serge

    2013-05-01

    At the time of the two last solar total eclipses of August 1st, 2008 in Siberia and July 11th, 2010 in French Polynesia, high frame rate CCD flash spectra were obtained. These eclipses occurred in quiet Sun period and after. The slitless flash spectra show two helium shells, in the weak Paschen α 4686 Å line of the ionized helium HeII and in the neutral helium HeI line at 4713 Å. The extensions of these helium shells are typically 3 Mm. In prominences, the extension of the interface with the corona is much more extended. The observations and analysis of these lines can properly be done only in eclipse conditions, when the intensity threshold reaches the coronal level, and the parasitic scattered light is virtually zero. Under the layers of 1 Mm above the limb, many faint low FIP lines were also seen in emission. These emission lines are superposed on the continuum containing absorption lines. The solar limb can be defined using the weak continuum appearing between the emission lines at the time of the second and third contact. The variations of the singly ionized iron line, the HeI and HeII lines and the continuum intensity are analyzed. The intensity ratio of ionized to neutral helium is studied for evaluating the ionization rate in low layers up to 2 Mm and also around a prominence.

  15. Helium shells and faint emission lines from slitless flash spectra

    NASA Astrophysics Data System (ADS)

    Bazin, Cyril; Koutchmy, Serge

    2013-05-01

    At the time of the two last solar total eclipses of August 1st, 2008 in Siberia and July 11th, 2010 in French Polynesia, high frame rate CCD flash spectra were obtained. These eclipses occurred in quiet Sun period and after. The slitless flash spectra show two helium shells, in the weak Paschen α 4686 Å line of the ionized helium HeII and in the neutral helium HeI line at 4713 Å. The extensions of these helium shells are typically 3 Mm. In prominences, the extension of the interface with the corona is much more extended. The observations and analysis of these lines can properly be done only in eclipse conditions, when the intensity threshold reaches the coronal level, and the parasitic scattered light is virtually zero. Under the layers of 1 Mm above the limb, many faint low FIP lines were also seen in emission. These emission lines are superposed on the continuum containing absorption lines. The solar limb can be defined using the weak continuum appearing between the emission lines at the time of the second and third contact. The variations of the singly ionized iron line, the HeI and HeII lines and the continuum intensity are analyzed. The intensity ratio of ionized to neutral helium is studied for evaluating the ionization rate in low layers up to 2 Mm and also around a prominence.

  16. Modeling Asymmetric Forbidden Line Emission Profiles in Supernovae with Clumping

    NASA Astrophysics Data System (ADS)

    Herrington, Jessica; Ignace, R.; Hole, K. T.

    2010-01-01

    There are some supernovae that display emission line profiles that are asymmetric in shape. One cause for asymmetry could be an in-homogeneous density distribution, or "clumps". We explore the effects of clumps on the emission line profiles of forbidden lines. Our model assumes the ejecta shell is spherically symmetric in velocity, with a central cavity. The model assigns density perturbations to conical sections in the ejecta. To model the emission profile for a forbidden line, we use Sobolev theory. Our model gives asymmetric profiles when the clumping is introduced. The amount of asymmetry varies with the range of density perturbations allowed, and the relative asymmetry evolves in time. This project was funded by a partnership between the National Science Foundation (NSF AST-0552798), Research Experiences for Undergraduates (REU), and the Department of Defense (DoD) ASSURE (Awards to Stimulate and Support Undergraduate Research Experiences) programs.

  17. First Detections of Compact AGN-triggered Radio Cores in RQ AGNs in the ECDFS

    NASA Astrophysics Data System (ADS)

    Prandoni, I.; Maini, A.; Norris, R. P.; Giovannini, G.; Spitler, L. R.

    2016-08-01

    The mechanism triggering the radio emission in Radio-Quiet (RQ) Active Galactic Nuclei (AGN), found to be a relevant component of the faint radio population in deep fields, is hotly debated. Most RQ AGNs are unresolved or barely resolved at a few arcsec scale, comparable to the host galaxy size. RQ AGNs have also been found to share many properties with Star Forming Galaxies (SFG). They have similar radio luminosities and similar optical- /infrared-to-radio flux ratios. Their radio luminosity functions show similar evolutionary trends, and their host galaxies have similar colours, optical morphologies and stellar masses. For all these reasons it was concluded that the radio emission in such RQ AGNs is mainly triggered by star formation (SF). However in the local Universe (z<0.5) it is well known that both AGN and SF processes can contribute to the total radio emission in RQ AGNs (see e.g., Seyfert 2 galaxies), and there is growing evidence that composite SF/AGN systems are common at mid to high redshift (z>1-2). We used the Australian Long Baseline Array to observe a number of RQ AGNs in the Extended Chandra Deep Field South (ECDFS), and we detected compact, high-surface-brightness radio cores in some of them. Our pilot study shows that at least some of the sources classified as radio quiet contain an AGN that can contribute significantly (~50% or more) to the total radio emission. This is a first direct evidence of the presence of such AGN-triggered radio emission in RQ AGNs at cosmological redshifts.

  18. The influence of local environment on the emergence of AGN activity in galaxies

    NASA Astrophysics Data System (ADS)

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

    2011-11-01

    We have carried out a spectroscopic study to determine the frequency and nature of the nuclear activity found in compact groups. With this aim we chose two samples, one selected from the Hickson Compact Groups Catalogue and another one from the Updated Zwicky Catalogue of Compact Groups. With the analysis of 1056 galaxies we found that more than 71% present some kind of emission, most of them, being low luminosity AGN (L_{Hα}=10^{39} erg s^{-1}). From these we only detect broad components in 16 which means a remarkable deficiency of broad line AGNs as compared to narrow lineAGNs, despite the high frequency of active galaxies encountered ingeneral in these groups.

  19. Retired galaxies: not to be forgotten in the quest of the star formation - AGN connection

    NASA Astrophysics Data System (ADS)

    Stasińska, G.; Costa-Duarte, M. V.; Vale Asari, N.; Cid Fernandes, R.; Sodré, L.

    2015-05-01

    We propose a fresh look at the Main Galaxy Sample of the Sloan Digital Sky Survey by packing the galaxies in stellar mass and redshift bins. We show how important it is to consider the emission-line equivalent widths, in addition to the commonly used emission-line ratios, to properly identify retired galaxies (i.e. galaxies that have stopped forming stars and are ionized by their old stellar populations) and not mistake them for galaxies with low-level nuclear activity. We find that the proportion of star-forming galaxies decreases with decreasing redshift in each mass bin, while that of retired galaxies increases. Galaxies with M⋆ > 1011.5 M⊙ have formed all their stars at redshift larger than 0.4. The population of AGN hosts is never dominant for galaxy masses larger than 1010 M⊙. We warn about the effects of stacking galaxy spectra to discuss galaxy properties. We estimate the lifetimes of active galactic nuclei (AGN) relying entirely on demographic arguments - i.e. without any assumption on the AGN radiative properties. We find upper-limit lifetimes of about 1-5 Gyr for detectable AGN in galaxies with masses between 1010-1012 M⊙. The lifetimes of the AGN-dominated phases are a few 108 yr. Finally, we compare the star formation histories of star-forming, AGN and retired galaxies as obtained by the spectral synthesis code STARLIGHT. Once the AGN is turned on, it inhibits star formation for the next ˜0.1 Gyr in galaxies with masses around 1010 M⊙, ˜ 1 Gyr in galaxies with masses around 1011 M⊙.

  20. Profiles of emission lines in Be stars.

    NASA Technical Reports Server (NTRS)

    Huang, S. S.

    1972-01-01

    Study of the broadening functions resulting from a gaseous ring in circular motion around a star according to Kepler's law. When the distribution in the gaseous ring has a circular symmetry in the equatorial plane, the broadening profile is related to the surface density distribution along the radius by an integral equation which can be transformed into the Abel integral equation and solved analytically. Profiles corresponding to gaseous rings with a uniform density distribution but different widths are used to illustrate the general properties of the profile broadened by the gaseous ring in circular motion. The emission profile has also been studied for cases in which the circular motion does not follow Kepler's law.

  1. Far-Infrared Line Emission from High Redshift Quasars

    NASA Technical Reports Server (NTRS)

    Benford, D. J.; Cox, P.; Hunter, T. R.; Malhotra, S.; Phillips, T. G.; Yun, M. S.

    2002-01-01

    Recent millimeter and submillimeter detections of line emission in high redshift objects have yielded new information and constraints on star formation at early epochs. Only CO transitions and atomic carbon transitions have been detected from these objects, yet bright far-infrared lines such as C+ at 158 microns and N+ at 205 microns should be fairly readily detectable when redshifted into a submillimeter atmospheric window. We have obtained upper limits for C+ emission &om two high redshift quasars, BR1202-0725 at z=4.69 and BRI1335-0415 at z=4.41. These limits show that the ratio of the C+ line luminosity to the total far-infrared luminosity is less than 0.0l%, ten times smaller than has been observed locally. Additionally, we have searched for emission in the N+ 205 micron line from the Cloverleaf quasar, H1413+117, and detected emission in CO J=7-6. The N+ emission is found to be below the amount predicted based on comparison to the only previous detection of this line, in the starburst galaxy M82.

  2. 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.

  3. Active galactic nuclei emission line diagnostics and the mass-metallicity relation up to redshift z ∼ 2: The impact of selection effects and evolution

    SciTech Connect

    Juneau, Stéphanie; Bournaud, Frédéric; Daddi, Emanuele; Elbaz, David; Duc, Pierre-Alain; Gobat, Raphael; Jean-Baptiste, Ingrid; Le Floc'h, Émeric; Pannella, Maurilio; Schreiber, Corentin; Trump, Jonathan R.; Dickinson, Mark

    2014-06-10

    Emission line diagnostic diagrams probing the ionization sources in galaxies, such as the Baldwin-Phillips-Terlevich (BPT) diagram, have been used extensively to distinguish active galactic nuclei (AGN) from purely star-forming galaxies. However, they remain poorly understood at higher redshifts. We shed light on this issue with an empirical approach based on a z ∼ 0 reference sample built from ∼300,000 Sloan Digital Sky Survey galaxies, from which we mimic selection effects due to typical emission line detection limits at higher redshift. We combine this low-redshift reference sample with a simple prescription for luminosity evolution of the global galaxy population to predict the loci of high-redshift galaxies on the BPT and Mass-Excitation (MEx) diagnostic diagrams. The predicted bivariate distributions agree remarkably well with direct observations of galaxies out to z ∼ 1.5, including the observed stellar mass-metallicity (MZ) relation evolution. As a result, we infer that high-redshift star-forming galaxies are consistent with having normal interstellar medium (ISM) properties out to z ∼ 1.5, after accounting for selection effects and line luminosity evolution. Namely, their optical line ratios and gas-phase metallicities are comparable to that of low-redshift galaxies with equivalent emission-line luminosities. In contrast, AGN narrow-line regions may show a shift toward lower metallicities at higher redshift. While a physical evolution of the ISM conditions is not ruled out for purely star-forming galaxies and may be more important starting at z ≳ 2, we find that reliably quantifying this evolution is hindered by selections effects. The recipes provided here may serve as a basis for future studies toward this goal. Code to predict the loci of galaxies on the BPT and MEx diagnostic diagrams and the MZ relation as a function of emission line luminosity limits is made publicly available.

  4. Active Galactic Nuclei Emission Line Diagnostics and the Mass-Metallicity Relation up to Redshift z ~ 2: The Impact of Selection Effects and Evolution

    NASA Astrophysics Data System (ADS)

    Juneau, Stéphanie; Bournaud, Frédéric; Charlot, Stéphane; Daddi, Emanuele; Elbaz, David; Trump, Jonathan R.; Brinchmann, Jarle; Dickinson, Mark; Duc, Pierre-Alain; Gobat, Raphael; Jean-Baptiste, Ingrid; Le Floc'h, Émeric; Lehnert, M. D.; Pacifici, Camilla; Pannella, Maurilio; Schreiber, Corentin

    2014-06-01

    Emission line diagnostic diagrams probing the ionization sources in galaxies, such as the Baldwin-Phillips-Terlevich (BPT) diagram, have been used extensively to distinguish active galactic nuclei (AGN) from purely star-forming galaxies. However, they remain poorly understood at higher redshifts. We shed light on this issue with an empirical approach based on a z ~ 0 reference sample built from ~300,000 Sloan Digital Sky Survey galaxies, from which we mimic selection effects due to typical emission line detection limits at higher redshift. We combine this low-redshift reference sample with a simple prescription for luminosity evolution of the global galaxy population to predict the loci of high-redshift galaxies on the BPT and Mass-Excitation (MEx) diagnostic diagrams. The predicted bivariate distributions agree remarkably well with direct observations of galaxies out to z ~ 1.5, including the observed stellar mass-metallicity (MZ) relation evolution. As a result, we infer that high-redshift star-forming galaxies are consistent with having normal interstellar medium (ISM) properties out to z ~ 1.5, after accounting for selection effects and line luminosity evolution. Namely, their optical line ratios and gas-phase metallicities are comparable to that of low-redshift galaxies with equivalent emission-line luminosities. In contrast, AGN narrow-line regions may show a shift toward lower metallicities at higher redshift. While a physical evolution of the ISM conditions is not ruled out for purely star-forming galaxies and may be more important starting at z >~ 2, we find that reliably quantifying this evolution is hindered by selections effects. The recipes provided here may serve as a basis for future studies toward this goal. Code to predict the loci of galaxies on the BPT and MEx diagnostic diagrams and the MZ relation as a function of emission line luminosity limits is made publicly available.

  5. Emission lines in the optical spectrum of 3 Cen A

    NASA Astrophysics Data System (ADS)

    Wahlgren, G. M.; Hubrig, S.

    2004-05-01

    Previously, weak emission lines had been detected at red wavelengths in the spectra of a limited sample of mid to late B type main sequence stars. A fuller description of the occurrence and origins of these lines has yet to be forwarded, in part due to the lack of observations detailing the spectral transitions involved. To address this deficiency, we present a line list of weak emission features found in the optical and near infrared spectral region of the chemically peculiar He-weak star 3 Cen A (HD 120709). Nearly 350 features, mostly associated with allowed transitions from high-excitation states of first ions, are catalogued along with identifications. Prominent among the emission lines are the spectra P II, Mn II, Fe II, Ni II and Cu II. Emission lines from Ca II, Si II and Hg II are also evident. Abundances are determined for several elements from synthetic spectrum fitting, with anomalies detected for the ions O I/II, P II/III and Si II/III. The LTE synthetic spectrum fitting also revealed that the low excitation 4s-4p transitions of Fe II predict an abundance that is greater than that determined from higher excitation 4d-4f transitions. Several of these latter transitions have upper energy levels that are found to be associated with emission lines. We also present empirical considerations for the excitation processes leading to the weak emission lines. Based on observations obtained at the European Southern Observatory, La Silla, Chile, No. 65.L-0316 and Paranal, Chile No. 266.D-5655. Tables 2 and 3 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/418/1073

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

    NASA Astrophysics Data System (ADS)

    Nardini, Emanuele

    Accretion onto the supermassive black holes located at the centre of Active Galactic Nuclei(AGN) is one of the most efficient power sources in the Universe, and provides a significant contribution to the energy radiated over cosmic times. The spectral shape of the X-ray background and its progressive resolution strongly suggests that most AGN are heavily obscured by large amounts of dust and gas. Their primary radiation field is reprocessed and re-emitted at longer wavelengths, driving a huge IR luminosity. Ultraluminous Infrared Galaxies (ULIRGs) are the local counterparts of the high-redshift (z < 1 3) IR systems that harbour the bulk of obscured nuclear activity in the early Universe. We have been recently awarded Suzaku observations of two ULIRGs, IRAS 00182 7112 and IRAS 12127 1412, for a total exposure time of 150 ks. Both the sources are known to host an elusive AGN whose intrinsic luminosity is estimated to fall in the quasar range. Although classified as Low-Ionization Nuclear Emission-line Regions in the optical, these ULIRGs sport the typical features of buried AGN in the mid-IR. IRAS 12127 1412 was observed for the first time in the X-rays by our group. Its Chandra spectrum clearly shows the signatures of AGN reflection at 2 10 keV. Similar properties were previously found in IRAS 00182 7112. Our Suzaku observations will allow to pinpont the AGN emission above 10 keV, and will provide fundamental information on the physical and geometrical structure of Compton-thick AGN embedded in a nuclear starburst. These sources are believed to experience the very initial phase of the AGN feedback on the surrounding environment, eventually leading to the formation of powerful optically- bright quasars. Besides this, we stress another remarkable opportunity related to the study of these two ULIRGs. Due to their really unique mid-IR and hard X-ray spectral properties, IRAS 00182 7112 and IRAS 12127 1412 can be considered as representative templates for a significant

  7. Package for Interactive Analysis of Line Emission

    NASA Technical Reports Server (NTRS)

    Kashyap, Vinay; Hunter, Paul (Technical Monitor)

    2005-01-01

    PINTofALE is an IDL based package to analyze high-resolution grating spectra. The first version was made available to the public on 3 February 2001. Since then we have carried out numerous changes and subsidiary releases. The current release is version 2.0 (released 6 Apr 2004), and we are preparing to release v2.1 within the next month. The changes include bug fixes, upgrades to handle higher versions of IDL and the CHIANTI database, enhancements in user-friendliness, handling of instrument response matrices, and the release of a Markov Chain Monte Carlo based DEM fitting routines. A detailed description of the package, together with fairly detailed documentation, example walk-throughs, and downloadable tar files, are available on-line from http://hea.harvard.edu/PINTofALE/ The website also lists papers that have used PINTofALE in their analysis.

  8. Emission Line Spectra from Low-Density Laboratory Plasmas

    NASA Technical Reports Server (NTRS)

    Beiersdorfer, P.; Brown, G. V.; Drake, J. J.; Gu, M.-F.; Kahn, S. M.; Lepson, J. K.; Liedahl, D. A.; Mauche, C. W.; Savin, D. W.; Utter, S. B.; Wargelin, B. J.

    2000-01-01

    Using spectroscopic equipment optimized for laboratory astrophysics, we are performing systematic measurements of the line emission from astrophysically relevant ions in the wavelength band between 1 and 400 Angstroms important to X-ray missions such as Chandra, XMM, Astro-E, and EUVE. Obtained in a controlled laboratory setting at electron densities similar to those found in stellar coronae, the data are used to test spectral modeling codes for accuracy and completeness. Our effort includes the compilation of the iron L-shell emission lines from 6-18 Angstroms and the iron M-shell emission lines from 50-200 Angstroms. Many lines have been identified for the first time, and the fluxes from lines missing in the spectral modeling codes are assessed. Our measurements also assess the accuracy of line excitation calculations, including direct electron-impact excitation, dielectronic recombination, and resonance excitation. These measurements yield a calibration of specific diagnostic line ratios. Examples of our current measurements are given.

  9. Edge region hydrogen line emission in the PDX tokamak

    SciTech Connect

    McNeill, D.H.; Bell, M.G.; Grek, B.; LeBlanc, B.

    1984-02-01

    Measurements of the H/sub ..cap alpha../ line shape and of the spatial distribution of the H/sub ..cap alpha../ emissivity in the PDX tokamak are interpreted in terms of molecular dissociation reactions at the plasma edge. The influx of molecules is shown to be roughly proportional to the edge emission intensity over a wide range of temperatures. The H/sub 2/ particle lifetime is estimated for various types of discharges in PDX.

  10. Edge region hydrogen line emission in the PDX tokamak

    SciTech Connect

    McNeill, D.H.; Bell, M.G.; Grek, B.; LeBlanc, B.

    1984-04-01

    Measurements of the H/sub ..cap alpha../ line shape and of the spatial distribution of H/sub ..cap alpha../ emissivity in the PDX tokamak are interpreted in terms of molecular dissociation reactions at the plasma edge. The in-flux of molecules is shown to be roughly proportional to the edge emission intensity over a wide range of temperatures. The H/sub 2/ particle lifetime is estimated for various types of discharges in PDX.

  11. Hard X-ray spectral properties of distant AGN in the NuSTAR surveys

    NASA Astrophysics Data System (ADS)

    Del Moro, Agnese

    2016-08-01

    I will present a study on the average broad X-ray band (~0.5-30 keV) spectral properties of the NuSTAR sources detected in the ECDF-S, EGS and COSMOS fields. Constructing the rest-frame composite spectra of AGN in different hydrogen column density (NH) and 10-40 keV luminosity bins, using Chandra and NuSTAR data, we investigate the typical spectral parameters of the AGN population, such as the photon index, NH, strength of the iron emission line (~6.4 keV) and of the Compton reflection at ~20-30 keV. Placing constraints on the reflection fraction (R) is of particular importance for the synthesis models of the cosmic X-ray background (CXB), as this parameter is strongly linked with the fraction of Compton-thick AGN needed to fit the CXB spectrum. Thanks to its sensitivity at ~20-30 keV, NuSTAR allows for the first time, to directly place such constraints for non-local AGN. We find typical reflection fractions of R~1-1.5, consistent the AGN in the local Universe, with a tentative evidence for the most obscured AGN to have, on average, stronger Compton reflection compared to unobscured AGN. Moreover, contrary to previous works, we do not find significant evidence for a decrease of the reflection strength with luminosity for typical Γ=1.8-1.9. Our results support CXB models that require a relatively small fraction of CT AGN, of the order of ~10-15%.

  12. MICROLENSING OF QUASAR BROAD EMISSION LINES: CONSTRAINTS ON BROAD LINE REGION SIZE

    SciTech Connect

    Guerras, E.; Mediavilla, E.; Kochanek, C. S.; Munoz, J. A.; Falco, E.; Motta, V.

    2013-02-20

    We measure the differential microlensing of the broad emission lines between 18 quasar image pairs in 16 gravitational lenses. We find that the broad emission lines are in general weakly microlensed. The results show, at a modest level of confidence (1.8{sigma}), that high ionization lines such as C IV are more strongly microlensed than low ionization lines such as H{beta}, indicating that the high ionization line emission regions are more compact. If we statistically model the distribution of microlensing magnifications, we obtain estimates for the broad line region size of r{sub s} = 24{sup +22} {sub -15} and r{sub s} = 55{sup +150} {sub -35} lt-day (90% confidence) for the high and low ionization lines, respectively. When the samples are divided into higher and lower luminosity quasars, we find that the line emission regions of more luminous quasars are larger, with a slope consistent with the expected scaling from photoionization models. Our estimates also agree well with the results from local reveberation mapping studies.

  13. Measurement of coronal X-ray emission lines from Capella

    NASA Technical Reports Server (NTRS)

    Vedder, P. W.; Canizares, C. R.

    1983-01-01

    The Einstein Observatory's Focal Plane Crystal Spectrometer has detected X-ray emission lines due to O VIII, Fe XVII, and Fe XX, from the binary star system Capella. Line luminosities are well fitted by an emitting plasma at a single temperature of 6.29 + or - 0.01 - 0.03 million K, and a volume emission measure of about 8.6 x 10 to the 52nd/cu cm, corresponding to the low temperature component previously observed. A high temperature component is undetectable, since the observed lines are not produced in plasma at temperatures above about 20 million K. Nearly isothermal plasma would be expected if many of the magnetically confined coronal loops have similar sizes and pressures, and a second population of longer loops would be required to account for the hotter component. An alternative interpretation of the observed X-ray line emission and upper limit is that the plasma contains a continuous distribution of emission measure versus temperature that rises sharply to 3 million K and then falls by nearly a decade to 16 million. An extrapolation of the loop sizes suggested by this alternative to hotter, longer loops may also account for the higher temperature emission.

  14. Impurity Line Emissions in VUV Region of TCABR Tokamak

    SciTech Connect

    Machida, M.; Daltrini, A. M.; Severo, J. H. F.; Nascimento, I. C.; Sanada, E. K.; Elizondo, J. I.; Kuznetsov, Y. K.; Galvao, R. M. O.

    2008-04-07

    Spectral emissions in the vacuum ultraviolet region from 50 nm to 320 nm have been measured on TCABR tokamak using an one meter VUV spectrometer and a MCP coupled to a CCD detector. Among the 98 emissions classified, 37 are from first order diffraction, 29 are from second order, 24 are from third order, 7 from fourth order, and one from fifth order diffraction. Main impurity lines are OII to OVII, CII to CIV, NIII to N V, FVII, besides working gas plasma hydrogen Lyman lines.

  15. The dust covering factor in AGN

    NASA Astrophysics Data System (ADS)

    Stalevski, Marko

    2016-08-01

    We undertook a critical investigation of a common estimator of the dust covering factor in active galactic nuclei (AGN). The infrared radiation emitted by the obscuring dusty structure ("the dusty torus") is nothing but a reprocessed fraction of the accretion disk emission, so the ratio of their luminosities (L_torus /L_AGN) should correspond to the fraction of the AGN sky obscured by dust. Using state-of-the-art Monte Carlo radiative transfer code, we calculated a grid of spectral energy distributions (SEDs) emitted by the clumpy two-phase dusty structure. Using this grid of SEDs, we studied the relation between L_torus /L_AGN and the dust covering factor for different parameters of the torus. We found that in case of type 1 AGNs, due to the torus anisotropy, L_torus/L AGN underestimate low covering factors and overestimate high covering factors. In type 2 AGNs covering factors are always underestimated. Our results provide a novel easy-to-use method to account for anisotropy and obtain correct covering factors. Using two samples from the literature, we demonstrated the importance of these effects for inferring the obscured AGN fraction. We found that after the anisotropy is properly accounted for, the dust covering factors show very weak dependence on L_AGN, with values in the range of approx. 0.6 ‑ 0.7. Our results suggest a higher fraction of obscured AGNs at high luminosities than those found by X-ray surveys. We discuss the possible causes of this discrepancy and demonstrate that it is partially due to the presence of a Compton-thick AGN population, which is missed by X-ray surveys, but not by infrared.

  16. The MIXR sample: AGN activity versus star formation across the cross-correlation of WISE, 3XMM, and FIRST/NVSS

    NASA Astrophysics Data System (ADS)

    Mingo, B.; Watson, M. G.; Rosen, S. R.; Hardcastle, M. J.; Ruiz, A.; Blain, A.; Carrera, F. J.; Mateos, S.; Pineau, F.-X.; Stewart, G. C.

    2016-11-01

    We cross-correlate the largest available mid-infrared (Wide-field Infrared Survey Explorer - WISE), X-ray (3XMM) and radio (Faint Images of the Radio Sky at Twenty centimetres+NRAO VLA Sky Survey) catalogues to define the MIXR sample of AGN and star-forming galaxies. We pre-classify the sources based on their positions on the WISE colour/colour plot, showing that the MIXR triple selection is extremely effective to diagnose the star formation and AGN activity of individual populations, even on a flux/magnitude basis, extending the diagnostics to objects with luminosities and redshifts from SDSS DR12. We recover the radio/mid-IR star formation correlation with great accuracy, and use it to classify our sources, based on their activity, as radio-loud and radio-quiet active galactic nuclei (AGN), low excitation radio galaxies/low ionization nuclear emission line regions, and non-AGN galaxies. These diagnostics can prove extremely useful for large AGN and galaxy samples, and help develop ways to efficiently triage sources when data from the next generation of instruments becomes available. We study bias in detail, and show that while the widely used WISE colour selections for AGN are very successful at cleanly selecting samples of luminous AGN, they miss or misclassify a substantial fraction of AGN at lower luminosities and/or higher redshifts. MIXR also allows us to test the relation between radiative and kinetic (jet) power in radio-loud AGN, for which a tight correlation is expected due to a mutual dependence on accretion. Our results highlight that long-term AGN variability, jet regulation, and other factors affecting the Q/Lbol relation, are introducing a vast amount of scatter in this relation, with dramatic potential consequences on our current understanding of AGN feedback and its effect on star formation.

  17. Exploring the Connection Between Star Formation and AGN Activity in the Local Universe

    NASA Technical Reports Server (NTRS)

    LaMassa, Stephanie M.; Heckman. T. M.; Ptak, Andrew; Schiminovich, D.; O'Dowd, M.; Bertincourt, B.

    2012-01-01

    We study a combined sample of 264 star-forming, 51 composite, and 73 active galaxies using optical spectra from SDSS and mid-infrared (mid-IR) spectra from the Spitzer Infrared Spectrograph. We examine optical and mid-IR spectroscopic diagnostics that probe the amount of star formation and relative energetic con- tributions from star formation and an active galactic nucleus (AGN). Overall we find good agreement between optical and mid-IR diagnostics. Misclassifications of galaxies based on the SDSS spectra are rare despite the presence of dust obscuration. The luminosity of the [NeII] 12.8 micron emission-line is well correlated with the star formation rate (SFR) measured from the SDSS spectra, and this holds for the star forming, composite, and AGN-dominated systems. AGN show a clear excess of [NeIII] 15.6 micron emission relative to star forming and composite systems. We find good qualitative agreement between various parameters that probe the relative contributions of the AGN and star formation, including: the mid-IR spectral slope, the ratio of the [NeV] 14.3 micron to [NeII] micron 12.8 fluxes, the equivalent widths of the 7.7, 11.3, and 17 micron PAH features, and the optical "D" parameter which measures the distance a source lies from the locus of star forming galaxies in the optical BPT emission-line diagnostic diagram. We also consider the behavior of the three individual PAH features by examining how their flux ratios depend upon the degree of AGN-dominance. We find that the PAH 11.3 micron feature is significantly suppressed in the most AGN-dominated systems.

  18. Infrared [Fe II] Emission Lines from Radiative Atomic Shocks

    NASA Astrophysics Data System (ADS)

    Koo, Bon-Chul; Raymond, John C.; Kim, Hyun-Jeong

    2016-06-01

    [Fe II] emission lines are prominent in the infrared (IR) and important as diagnostic tools for radiative atomic shocks. We investigate the emission characteristics of [Fe II] lines using a shock code developed by te{raymond1979} with updated atomic parameters. We first review general characteristics of the IR [Fe II] emission lines from shocked gas, and derive their fluxes as a function of shock speed and ambient density. We have compiled available IR [Fe II] line observations of interstellar shocks and compare them to the ratios predicted from our model. The sample includes both young and old supernova remnants in the Galaxy and the Large Magellanic Cloud and several Herbig-Haro objects. We find that the observed ratios of the IR [Fe II] lines generally fall on our grid of shock models, but the ratios of some mid-IR lines, e.g., fethreefive/fetwofive, fefive/fetwofive, and fefive/feoneseven, are significantly offset from our model grid. We discuss possible explanations and conclude that while uncertainties in the shock modeling and the observations certainly exist, the uncertainty in atomic rates appears to be the major source of discrepancy.

  19. The OPTX Project. IV. How Reliable is [O III] as a Measure of AGN Activity?

    NASA Astrophysics Data System (ADS)

    Trouille, L.; Barger, A. J.

    2010-10-01

    We compare optical and hard X-ray identifications of active galactic nuclei (AGNs) using a uniformly selected (above a flux limit of f 2-8 keV = 3.5 × 10-15 erg cm-2 s-1) and highly optically spectroscopically complete (>80% for f 2-8 keV > 10-14 erg cm-2 s-1 and >60% below) 2-8 keV sample observed in three Chandra fields (CLANS, CLASXS, and the CDF-N). We find that empirical emission-line ratio diagnostic diagrams misidentify 50% of the X-ray-selected AGNs that can be put on these diagrams as star formers. We confirm that there is a large (two orders of magnitude) dispersion in the ratio of the [O III]λ5007 (hereafter [O III]) to hard X-ray luminosities for the non-broad-line AGNs, even after applying reddening corrections to the [O III] luminosities. We find that the dispersion is similar for the broad-line AGNs, where there is not expected to be much X-ray absorption from an obscuring torus around the AGN nor much obscuration from the galaxy along the line of sight if the AGN is aligned with the galaxy. We postulate that the X-ray-selected AGNs that are misidentified by the diagnostic diagrams have low [O III] luminosities due to the complexity of the structure of the narrow-line region, which causes many ionizing photons from the AGN not to be absorbed. This would mean that the [O III] luminosity can only be used to predict the X-ray luminosity to within a factor of ~3 (1σ). Despite selection effects, we show that the shapes and normalizations of the [O III] and transformed hard X-ray luminosity functions show reasonable agreement, suggesting that the [O III] samples are not finding substantially more AGNs at low redshifts than hard X-ray samples. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The observatory was made possible by the generous financial

  20. Physical Properties of Emission-Line Galaxies at 2 from Near-Infrared Spectroscopy with Magellan FIRE

    NASA Astrophysics Data System (ADS)

    Masters, Daniel C.; McCarthy, P. J.; Malkan, M. A.; Siana, B. D.; Scarlata, C.; Hathi, N. P.; Atek, H.; Henry, A. L.; WISP Team

    2014-01-01

    We present results from near-infrared spectroscopy with Magellan FIRE of 26 strong emission-line galaxies at 2.2 and 1.5. The sample was selected from the WFC3 Infrared Spectroscopic Parallels (WISP) survey, which uses the near-infrared grism capability of the Hubble Space Telescope Wide Field Camera 3 to detect emission-line galaxies over 0.5 < z < 2.3. High-resolution ( 5000) follow-up spectroscopy with Magellan FIRE over 1.0--2.5 microns resolves important rest-frame optical emission lines, allowing us to measure physical properties such as dust obscuration, metal abundance, star formation rate, ionization parameter, and emission line kinematics. We also analyze the properties of composite spectra derived from the FIRE-observed sample. With this relatively large sample of rest-frame optical spectra we can make statistical inferences about the population of emission-line galaxies at 2. We find that the galaxies are low metallicity ( 1/5-1/2 Z_solar) as determined from the R23 calibration. The galaxies are low dust extinction on average (E(B-V 0.2) but with significant scatter. The dust-corrected H-alpha star formation rates range from ~10--150 M_sun yr^-1 with a mean of 50 M_su yr^-1. The average ionization parameter for the sample, log U ~ -2.5, is higher than typically found for star-forming galaxies in the local universe but consistent with those found in more intense starbursting regions in galaxies such as M82. Emission line velocity dispersions are measured to be 71 +- 38 km s^-1, in good agreement with other studies that have probed the H-alpha kinematics of star-forming galaxies at similar redshift. The galaxies are compact, with half-light radii of < 2 kpc, and ~50% show evidence for multiple structures or asymmetries in the WFC3 imaging. Based on the line velocity dispersions and the location of the galaxies on BPT diagnostic plots, there is little evidence for significant AGN contribution to most emission-line galaxies at 2.

  1. Emission-line variability and distance of quasars.

    PubMed

    Pfleiderer, J; Grewing, M

    1967-08-01

    The radius of the line-emitting region in quasars is larger than 1 parsec for the cosmological hypothesis and smaller than 1 parsec for the local hypothesis. Variability in emission lines has been reported but not proved beyond doubt. Its time scale would be a direct observational indicator of this radius and would add an important element to the discussion of the origin of quasars. Objects that are variable in their optical continuum seem to be the most promising ones to look at for line variations, and they should be observed spectroscopically at regular intervals.

  2. The Subaru FMOS galaxy redshift survey (FastSound). II. The emission line catalog and properties of emission line galaxies

    NASA Astrophysics Data System (ADS)

    Okada, Hiroyuki; Totani, Tomonori; Tonegawa, Motonari; Akiyama, Masayuki; Dalton, Gavin; Glazebrook, Karl; Iwamuro, Fumihide; Ohta, Kouji; Takato, Naruhisa; Tamura, Naoyuki; Yabe, Kiyoto; Bunker, Andrew J.; Goto, Tomotsugu; Hikage, Chiaki; Ishikawa, Takashi; Okumura, Teppei; Shimizu, Ikkoh

    2016-06-01

    We present basic properties of ˜3300 emission line galaxies detected by the FastSound survey, which are mostly Hα emitters at z ˜ 1.2-1.5 in the total area of about 20 deg2, with the Hα flux sensitivity limit of ˜1.6 × 10-16 erg cm-2 s-1 at 4.5 σ. This paper presents the catalog of the FastSound emission lines and galaxies, which is open to the public. We also present basic properties of typical FastSound Hα emitters, which have Hα luminosities of 1041.8-1043.3 erg s-1, star formation rates (SFRs) of 20-500 M⊙ yr-1, and stellar masses of 1010.0-1011.3 M⊙. The 3D distribution maps for the four fields of Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) W1-4 are presented, clearly showing large scale clustering of galaxies at the scale of ˜100-600 comoving Mpc. Based on 1105 galaxies with detections of multiple emission lines, we estimate that the contamination of non-Hα lines is about 4% in the single-line emission galaxies, which is mostly [O III]λ5007. This contamination fraction is also confirmed by the stacked spectrum of all the FastSound spectra, in which Hα, [N II]λλ6548,6583, [S II]λλ6717,6731, and [O I]λλ6300,6364 are seen.

  3. AGNfitter: An MCMC Approach to Fitting SEDs of AGN and galaxies

    NASA Astrophysics Data System (ADS)

    Calistro Rivera, Gabriela; Lusso, Elisabeta; Hennawi, Joseph; Hogg, David W.

    2016-08-01

    I will present AGNfitter: a tool to robustly disentangle the physical processes responsible for the emission of active galactic nuclei (AGN). AGNfitter is the first open-source algorithm based on a Markov Chain Monte Carlo method to fit the spectral energy distributions of AGN from the sub-mm to the UV. The code makes use of a large library of theoretical, empirical, and semi-empirical models to characterize both the host galaxy and the nuclear emission simultaneously. The model consists in four physical components comprising stellar populations, cold dust distributions in star forming regions, accretion disk, and hot dust torus emissions. AGNfitter is well suited to infer numerous parameters that rule the physics of AGN with a proper handling of their confidence levels through the sampling and assumptions-free calculation of their posterior probability distributions. The resulting parameters are, among many others, accretion disk luminosities, dust attenuation for both galaxy and accretion disk, stellar masses and star formation rates. We describe the relevance of this fitting machinery, the technicalities of the code, and show its capabilities in the context of unobscured and obscured AGN. The analyzed data comprehend a sample of 714 X-ray selected AGN of the XMM-COSMOS survey, spectroscopically classified as Type1 and Type2 sources by their optical emission lines. The inference of variate independent obscuration parameters allows AGNfitter to find a classification strategy with great agreement with the spectroscopical classification for ˜ 86% and ˜ 70% for the Type1 and Type2 AGNs respectively. The variety and large number of physical properties inferred by AGNfitter has the potential of contributing to a wide scope of science-cases related to both active and quiescent galaxies studies.

  4. Empirical links between XRB and AGN accretion using the complete z < 0.4 spectroscopic CSC/SDSS catalog

    SciTech Connect

    Trichas, Markos; Green, Paul J.; Aldcroft, Tom; Sobolewska, Malgosia; Kim, Dong-Woo; Constantin, Anca; Kalfountzou, Eleni; Hyde, Ashley K.; Zhou, Hongyan; Haggard, Daryl; Kelly, Brandon C.

    2013-12-01

    Striking similarities have been seen between accretion signatures of Galactic X-ray binary (XRB) systems and active galactic nuclei (AGNs). XRB spectral states show a V-shaped correlation between X-ray spectral hardness and Eddington ratio as they vary, and some AGN samples reveal a similar trend, implying analogous processes at vastly larger masses and timescales. To further investigate the analogies, we have matched 617 sources from the Chandra Source Catalog to Sloan Digital Sky Survey spectroscopy, and uniformly measured both X-ray and optical spectral characteristics across a broad range of AGN and galaxy types. We provide useful tabulations of X-ray spectral slope for broad- and narrow-line AGNs, star-forming and passive galaxies, and composite systems, also updating relationships between optical (Hα and [O III]) line emission and X-ray luminosity. We further fit broadband spectral energy distributions with a variety of templates to estimate bolometric luminosity. Our results confirm a significant trend in AGNs between X-ray spectral hardness and Eddington ratio expressed in X-ray luminosity, albeit with significant dispersion. The trend is not significant when expressed in the full bolometric or template-estimated AGN luminosity. We also confirm a relationship between the X-ray/optical spectral slope α{sub ox} and Eddington ratio, but it may not follow the trend predicted by analogy with XRB accretion states.

  5. EQUIB: Atomic level populations and line emissivities calculator

    NASA Astrophysics Data System (ADS)

    Howarth, I. D.; Adams, S.; Clegg, R. E. S.; Ruffle, D. P.; Liu, X.-W.; Pritchet, C. J.; Ercolano, B.

    2016-03-01

    The Fortran program EQUIB solves the statistical equilibrium equation for each ion and yields atomic level populations and line emissivities for given physical conditions, namely electron temperature and electron density, appropriate to the zones in an ionized nebula where the ions are expected to exist.

  6. Exploring star formation in high-z galaxies using atomic and molecular emission lines

    NASA Astrophysics Data System (ADS)

    Gullberg, Bitten

    2016-03-01

    The conditions under which stars are formed and the reasons for triggering and quenching of starburst events in high-z galaxies, are still not well understood. Studying the interstellar medium (ISM) and the morphology of high-z galaxies are therefore key points in order to understand galaxy evolution. The cosmic star formation rate density peaks between 1AGN). This thesis presents three studies of the ISM in high-z galaxies and their morphologies by: Exploring the physical conditions of the ISM in a sample of dusty star-forming galaxies (DSFGs) using the relative observed line strength of ionised carbon ([CII]) and carbon monoxide (CO). We find that the line ratios can best be described by a medium of [CII] and CO emitting gas with a higher [CII] than CO excitation temperature, high CO optical depth tau(CO)>>1, and low to moderate [CII] optical depth tau(CII)<1. Combining millimetre/sub-millimetre and optical data cubes for the high-z radio galaxy (HzRG) MRC0943-242, has revealed a much more complicated morphology than seen in the individual data sets. The millimetre/sub-millimetre observations data have allowed us to spatially separate of the AGN and starburst dominated components, which ~65 kpc apart. The optical data reveal structures of emitting and absorbing gas at multiple wavelengths. A deep high resolution millimetre/sub-millimetre study of the HzRG MRC1138-262, shows emission from water (H2O) and an unusually large amount of neutral atomic carbon ([CI]) relative to highly excited CO compared to lensed DSFGs. The

  7. Electromagnetic plasma wave emissions from the auroral field lines

    NASA Technical Reports Server (NTRS)

    Gurnett, D. A.

    1977-01-01

    The most important types of auroral radio emissions are reviewed, both from a historical perspective as well as considering the latest results. Particular emphasis is placed on four types of electromagnetic emissions which are directly associated with the plasma on the auroral field lines. These emissions are (1) auroral hiss, (2) saucers, (3) ELF noise bands, and (4) auroral kilometric radiation. Ray tracing and radio direction finding measurements indicate that both the auroral hiss and auroral kilometric radiation are generated along the auroral field lines relatively close to the earth, at radial distances from about 2.5 to 5 R sub e. For the auroral hiss the favored mechanism appears to be amplified Cerenkov radiation. For the auroral kilometric radiation several mechanisms have been proposed, usually involving the intermediate generation of electrostatic waves by the precipitating electrons.

  8. 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.

  9. The Chandra View of Radiative and Kinetic Dissipation in AGN: Toward a Complete Picture of Energy Transport in Active Galaxies

    NASA Astrophysics Data System (ADS)

    Evans, Daniel A.; Lee, J.; Turner, J.; Kraft, R.; Bianchi, S.; Hardcastle, M.; Marshall, H.; Gallagher, S.; Weaver, K.; Canizares, C.

    2009-01-01

    X-ray grating spectroscopy, combined with high-resolution multiwavelength imaging, are powerful tools for probing the nuclei and circumnuclear environments of AGN and elucidating the connections between accretion and outflows in active galaxies. We present the results from a new series of Chandra, XMM-Newton, and Suzaku observations of radio-loud and radio-quiet AGN, and address the following questions: 1) What are the roles of photoionization and outflows in creating the ionized kpc-scale circumnuclear environments of AGN. How does this affect the gas supply to the black hole? 2) What are the physical conditions of the accretion flow and absorption in AGN? Are there intrinsic differences between radio-loud and radio-quiet AGN, and what does this imply for the disk-jet connection? First, we use X-ray gratings spectroscopy and imaging to provide detailed diagnostics of the spatially resolved, multiphase narrow-line regions (NLRs) in Seyfert galaxies. These AGN show a range of outflow properties, from truly radio-quiet sources to those with kpc-scale outflows. The detection of narrow RRC features and He-like triplets with the HETG and RGS spectrometers, strongly suggests that photoionization from the AGN dominates the energetics of these kpc-scale regions. However, additional constraints from VLA, HST, and Chandra imaging indicate that jets also play a significant role in governing their environments. We discuss the consequences for models that link outflows with feedback between accretion and black-hole growth. Next, we examine the connection between accretion and jet production in AGN with new Suzaku observations. We show that radio-loud AGN systematically tend to lack the signatures of reprocessed X-ray emission from an neutral accretion disk that are commonly observed in radio-quiet sources. This has important implications for the structure of accretion flow in its inner regions and supports models in which the accretion flow plays a prominent role in the

  10. Extreme Ultraviolet Emission Lines of Iron Fe XI-XIII

    NASA Astrophysics Data System (ADS)

    Lepson, Jaan; Beiersdorfer, P.; Brown, G. V.; Liedahl, D. A.; Brickhouse, N. S.; Dupree, A. K.

    2013-04-01

    The extreme ultraviolet (EUV) spectral region (ca. 20--300 Å) is rich in emission lines from low- to mid-Z ions, particularly from the middle charge states of iron. Many of these emission lines are important diagnostics for astrophysical plasmas, providing information on properties such as elemental abundance, temperature, density, and even magnetic field strength. In recent years, strides have been made to understand the complexity of the atomic levels of the ions that emit the lines that contribute to the richness of the EUV region. Laboratory measurements have been made to verify and benchmark the lines. Here, we present laboratory measurements of Fe XI, Fe XII, and Fe XIII between 40-140 Å. The measurements were made at the Lawrence Livermore electron beam ion trap (EBIT) facility, which has been optimized for laboratory astrophysics, and which allows us to select specific charge states of iron to help line identification. We also present new calculations by the Hebrew University - Lawrence Livermore Atomic Code (HULLAC), which we also utilized for line identification. We found that HULLAC does a creditable job of reproducing the forest of lines we observed in the EBIT spectra, although line positions are in need of adjustment, and line intensities often differed from those observed. We identify or confirm a number of new lines for these charge states. This work was supported by the NASA Solar and Heliospheric Program under Contract NNH10AN31I and the DOE General Plasma Science program. Work was performed in part under the auspices of the Department of Energy by Lawrence Livermore National Laboratory under Contract DEAC52-07NA27344.

  11. Spectrophotometry of emission-line stars in the magellanic clouds

    NASA Technical Reports Server (NTRS)

    Bohannan, Bruce

    1990-01-01

    The strong emission lines in the most luminous stars in the Magellanic Clouds indicate that these stars have such strong stellar winds that their photospheres are so masked that optical absorption lines do not provide an accurate measure of photospheric conditions. In the research funded by this grant, temperatures and gravities of emission-line stars both in the Large (LMC) and Small Magellanic Clouds (SMC) have been measured by fitting of continuum ultraviolet-optical fluxes observed with IUE with theoretical model atmospheres. Preliminary results from this work formed a major part of an invited review 'The Distribution of Types of Luminous Blue Variables'. Interpretation of the IUE observations obtained in this grant and archive data were also included in a talk at the First Boulder-Munich Hot Stars Workshop. Final results of these studies are now being completed for publication in refereed journals.

  12. Baldwin Effect and Additional BLR Component in AGN with Superluminal Jets

    NASA Astrophysics Data System (ADS)

    Patiño Álvarez, Víctor; Torrealba, Janet; Chavushyan, Vahram; Cruz González, Irene; Arshakian, Tigran; León Tavares, Jonathan; Popovic, Luka

    2016-06-01

    We study the Baldwin Effect (BE) in 96 core-jet blazars with optical and ultraviolet spectroscopic data from a radio-loud AGN sample obtained from the MOJAVE 2cm survey. A statistical analysis is presented of the equivalent widths W_lambda of emission lines H beta 4861, Mg II 2798, C IV 1549, and continuum luminosities at 5100, 3000, and 1350 angstroms. The BE is found statistically significant (with confidence level c.l. > 95%) in H beta and C IV emission lines, while for Mg II the trend is slightly less significant (c.l. = 94.5%). The slopes of the BE in the studied samples for H beta and Mg II are found steeper and with statistically significant difference than those of a comparison radio-quiet sample. We present simulations of the expected BE slopes produced by the contribution to the total continuum of the non-thermal boosted emission from the relativistic jet, and by variability of the continuum components. We find that the slopes of the BE between radio-quiet and radio-loud AGN should not be different, under the assumption that the broad line is only being emitted by the canonical broad line region around the black hole. We discuss that the BE slope steepening in radio AGN is due to a jet associated broad-line region.

  13. K alpha line emission during solar X-ray bursts

    NASA Technical Reports Server (NTRS)

    Phillips, K. J. H.; Neupert, W. M.

    1973-01-01

    Calculations of K alpha line emission from S, Ar, Ca and Fe are presented. It is reported that on the basis of data for hard X-ray bursts, the flux during most impulsive, non-thermal events is likely to be weak, though for a few strong bursts, a flux of approximately 100 photons/cm/s may be expected. The amount of S K alpha emission particularly is sensitively dependent on the value of the lower energy bound of the non-thermal electron distribution, offering a possible means of determining this. Thermal K alpha emission is only significant for Fe ions. The calculated thermal K alpha radiation is much less than that observed during an intense soft X-ray burst. It is concluded that a detailed temperature structure for the emission source is required in order to explain the discrepancy.

  14. Radiative Transfer Effects in He I Emission Lines

    NASA Astrophysics Data System (ADS)

    Benjamin, Robert A.; Skillman, Evan D.; Smits, Derck P.

    2002-04-01

    We consider the effect of optical depth of the 23S level on the nebular recombination spectrum of He I for a spherically symmetric nebula with no systematic velocity gradients. These calculations, using many improvements in atomic data, can be used in place of the earlier calculations of Robbins. We give representative Case B line fluxes for UV, optical, and IR emission lines over a range of physical conditions: T=5000-20,000 K, ne=1-108 cm-3, and τ3889=0-100. A FORTRAN program for calculating emissivities for all lines arising from quantum levels with n<=10 is also available from the authors. We present a special set of fitting formulae for the physical conditions relevant to low-metallicity extragalactic H II regions: T=12,000-20,000 K, ne=1-300 cm-3, and τ3889<2.0). For this range of physical conditions, the Case B line fluxes of the bright optical lines 4471 Å, 5876 Å, and 6678 Å, are changed less than 1%, in agreement with previous studies. However, the 7065 Å corrections are much smaller than those calculated by Izotov & Thuan based on the earlier calculations by Robbins. This means that the 7065 Å line is a better density diagnostic than previously thought. Two corrections to the fitting functions calculated in our previous work are also given.

  15. What are the galaxies that host MIR-selected AGN?

    NASA Astrophysics Data System (ADS)

    Rosario, David

    2016-08-01

    Infra-red selection techniques, sensitive to dust strongly heated by an AGN, offer a way to identify some of the most obscured accretion events in the Universe. I will describe the results of a comprehensive multi-wavelength study of AGN to z>2 selected using Spitzer/IRAC based methods in the COSMOS field. Armed with AGN-optimised redshifts and stellar masses, we explore the dust emission from the active nucleus and the host galaxy. We demonstrate that IR-selected AGN tend to be found in low mass host galaxies, when compared to other AGN identification methods. The star-formation rates of obscured and unobscured IR-selected AGN are very similar, implying that large-scale obscuration with co-eval star-bursts are not found in a major proportion of heavily obscured AGN.

  16. HST-COS observations of AGNs. II. Extended survey of ultraviolet composite spectra from 159 active galactic nuclei

    SciTech Connect

    Stevans, Matthew L.; Shull, J. Michael; Danforth, Charles W.; Tilton, Evan M. E-mail: michael.shull@colorado.edu E-mail: evan.tilton@colorado.edu

    2014-10-10

    The ionizing fluxes from quasars and other active galactic nuclei (AGNs) are critical for interpreting their emission-line spectra and for photoionizing and heating the intergalactic medium. Using far-ultraviolet (FUV) spectra from the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST), we directly measure the rest-frame ionizing continua and emission lines for 159 AGNs at redshifts 0.001 < z {sub AGN} < 1.476 and construct a composite spectrum from 475 to 1875 Å. We identify the underlying AGN continuum and strong extreme ultraviolet (EUV) emission lines from ions of oxygen, neon, and nitrogen after masking out absorption lines from the H I Lyα forest, 7 Lyman-limit systems (N{sub H} {sub I}≥10{sup 17.2} cm{sup –2}) and 214 partial Lyman-limit systems (14.5AGNs exhibit a wide range of FUV/EUV spectral shapes, F{sub ν}∝ν{sup α{sub ν}}, typically with –2 ≤ α{sub ν} ≤ 0 and no discernible continuum edges at 912 Å (H I) or 504 Å (He I). The composite rest-frame continuum shows a gradual break at λ{sub br} ≈ 1000 Å, with mean spectral index α{sub ν} = –0.83 ± 0.09 in the FUV (1200-2000 Å) steepening to α{sub ν} = –1.41 ± 0.15 in the EUV (500-1000 Å). We discuss the implications of the UV flux turnovers and lack of continuum edges for the structure of accretion disks, AGN mass inflow rates, and luminosities relative to Eddington values.

  17. The Close AGN Reference Survey (CARS). Mrk 1018 returns to the shadows after 30 years as a Seyfert 1

    NASA Astrophysics Data System (ADS)

    McElroy, R. E.; Husemann, B.; Davis, T. A.; Bennert, V. N.; Busch, G.; Combes, F.; Eckart, A.; Perez-Torres, M.; Powell, M.; Scharwächter, J.; Tremblay, G. R.; Urrutia, T.

    2016-09-01

    We report the discovery that the known "changing look" AGN Mrk 1018 has changed spectral type for a second time. New VLT-MUSE data taken in 2015 as part of the Close AGN Reference Survey (CARS) shows that the AGN has returned to its original Seyfert 1.9 classification. The CARS sample is selected to contain only bright type 1 AGN, but Mrk 1018's broad emission lines and continuum, typical of type 1 AGN, have almost entirely disappeared. We use spectral fitting of the MUSE spectrum and previously available spectra to determine the drop in broad line flux and the Balmer decrement. We find that the broad line flux has decreased by a factor of 4.75 ± 0.5 in Hα since an SDSS spectrum was taken in 2000. The Balmer decrement has not changed significantly implying no enhanced reddening with time, but the remaining broad lines are more asymmetric than those present in the type 1 phase. We posit that the change is due to an intrinsic drop in flux from the accretion disk rather than variable extinction or a tidal disruption event.

  18. 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.

  19. Emission lines in the magnetic white dwarf GD 356

    NASA Astrophysics Data System (ADS)

    Greenstein, J. L.; McCarthy, J. K.

    1985-02-01

    Spectrographic measurements of the magnetic white dwarf GC 356 are presented, and, two weak emission line Zeeman triplets at H-alpha and H-beta are analyzed. The measurements were carried out using a high signal-to-noise ratio double spectrograph and CCD detectors attached to the Hale 5 meter refector telescope. Multichannel spectrophotometry of GD 356 indicated a temperature of about 7500 K. The H-alpha absorption triplet in G99-47 was studied, in order to correct emission measurements in GD 356. After scaling the absorption lines in G99 47 to fit the field in GD 356, the corrected H-alpha emission increased by 50 percent. The final H-alpha profile is represented by random fields of 11.0 megagauss with a spread of 1.1 megagauss. On the basis of the emission line analysis, some possible reasons for the absence of polarization in GD are discussed, including: (1) that GD 356 has an interacting companion; (2) that active convection in GD 356 interacts with the magnetic field to produce magnetoionic heating; and (3) that there is an ongoing accretion of interstellar matter in GD 356. It is suggested that GD 356 may be detectable with the IUE ultraviolet observatory.

  20. 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.

  1. Measurement of the deuterium Balmer series line emission on EAST

    NASA Astrophysics Data System (ADS)

    Wu, C. R.; Huang, J.; Gao, W.; Gao, W.; Xu, Z.; Chang, J. F.; Hou, Y. M.; Jin, Z.; Xu, J. C.; Duan, Y. M.; Zhang, P. F.; Chen, Y. J.; Zhang, L.; Wu, Z. W.; Li, J. G.

    2016-11-01

    Volume recombination plays an important role towards plasma detachment for magnetically confined fusion devices. High quantum number states of the Balmer series of deuterium are used to study recombination. On EAST (Experimental Advanced Superconducting Tokamak), two visible spectroscopic measurements are applied for the upper/lower divertor with 13 channels, respectively. Both systems are coupled with Princeton Instruments ProEM EMCCD 1024B camera: one is equipped on an Acton SP2750 spectrometer, which has a high spectral resolution ˜0.0049 nm with 2400 gr/mm grating to measure the Dα(Hα) spectral line and with 1200 gr/mm grating to measure deuterium molecular Fulcher band emissions and another is equipped on IsoPlane SCT320 using 600 gr/mm to measure high-n Balmer series emission lines, allowing us to study volume recombination on EAST and to obtain the related line averaged plasma parameters (Te, ne) during EAST detached phases. This paper will present the details of the measurements and the characteristics of deuterium Balmer series line emissions during density ramp-up L-mode USN plasma on EAST.

  2. Discovery of Polarized Line Emission in SN 1006

    NASA Astrophysics Data System (ADS)

    Sparks, W. B.; Pringle, J. E.; Carswell, R. F.; Long, K. S.; Cracraft, M.

    2015-12-01

    Laming predicted that the narrow Balmer line core of the ∼3000 km s‑1 shock in the SN 1006 remnant would be significantly polarized due to electron and proton impact polarization. Here, based on deep spectrally resolved polarimetry obtained with the European Southern Observatory (ESO)’s Very Large Telescope (VLT), we report the discovery of polarized line emission with a polarization degree of 1.3% and position angle orthogonal to the SNR filament. Correcting for an unpolarized broad line component, the implied narrow line polarization is ≈2.0%, close to the predictions of Laming. The predicted polarization is primarily sensitive to shock velocity and post-shock temperature equilibration. By measuring polarization for the SN 1006 remnant, we validate and enable a new diagnostic that has important applications in a wide variety of astrophysical situations, such as shocks, intense radiation fields, high energy particle streams, and conductive interfaces.

  3. DISCOVERY OF POLARIZED LINE EMISSION IN SN 1006

    SciTech Connect

    Sparks, W. B.; Pringle, J. E.; Long, K. S.; Cracraft, M.; Carswell, R. F.

    2015-12-10

    Laming predicted that the narrow Balmer line core of the ∼3000 km s{sup −1} shock in the SN 1006 remnant would be significantly polarized due to electron and proton impact polarization. Here, based on deep spectrally resolved polarimetry obtained with the European Southern Observatory (ESO)’s Very Large Telescope (VLT), we report the discovery of polarized line emission with a polarization degree of 1.3% and position angle orthogonal to the SNR filament. Correcting for an unpolarized broad line component, the implied narrow line polarization is ≈2.0%, close to the predictions of Laming. The predicted polarization is primarily sensitive to shock velocity and post-shock temperature equilibration. By measuring polarization for the SN 1006 remnant, we validate and enable a new diagnostic that has important applications in a wide variety of astrophysical situations, such as shocks, intense radiation fields, high energy particle streams, and conductive interfaces.

  4. Anisotropic alpha emission from on-line separated isotopes

    SciTech Connect

    Wouters, J.; Vandeplassche, D.; van Walle, E.; Severijns, N.; Vanneste, L.

    1986-05-05

    A systematic on-line nuclear-orientation study of heavy isotopes using anisotropic ..cap alpha.. emission is reported for the first time. The anisotrophies recorded for /sup 199/At, /sup 201/At, and /sup 203/At are remarkably pronounced and strongly varying. At lower neutron number the ..cap alpha.. particles are more preferentially emitted perpendicularly to the nuclear-spin direction. This may be interpreted in terms of the high sensitivity of the ..cap alpha..-emission probability to changes in the nuclear shape.

  5. The Herschel Comprehensive (U)LIRG Emission Survey (HERCULES): CO Ladders, Fine Structure Lines, and Neutral Gas Cooling

    NASA Astrophysics Data System (ADS)

    Rosenberg, M. J. F.; van der Werf, P. P.; Aalto, S.; Armus, L.; Charmandaris, V.; Díaz-Santos, T.; Evans, A. S.; Fischer, J.; Gao, Y.; González-Alfonso, E.; Greve, T. R.; Harris, A. I.; Henkel, C.; Israel, F. P.; Isaak, K. G.; Kramer, C.; Meijerink, R.; Naylor, D. A.; Sanders, D. B.; Smith, H. A.; Spaans, M.; Spinoglio, L.; Stacey, G. J.; Veenendaal, I.; Veilleux, S.; Walter, F.; Weiß, A.; Wiedner, M. C.; van der Wiel, M. H. D.; Xilouris, E. M.

    2015-03-01

    (Ultra) luminous infrared galaxies ((U)LIRGs) are objects characterized by their extreme infrared (8-1000 μm) luminosities (L LIRG > 1011 L ⊙ and L ULIRG > 1012 L ⊙). The Herschel Comprehensive ULIRG Emission Survey (PI: van der Werf) presents a representative flux-limited sample of 29 (U)LIRGs that spans the full luminosity range of these objects (1011 L ⊙ <= L IR <= 1013 L ⊙). With the Herschel Space Observatory, we observe [C II] 157 μm, [O I] 63 μm, and [O I] 145 μm line emission with Photodetector Array Camera and Spectrometer, CO J = 4-3 through J = 13-12, [C I] 370 μm, and [C I] 609 μm with SPIRE, and low-J CO transitions with ground-based telescopes. The CO ladders of the sample are separated into three classes based on their excitation level. In 13 of the galaxies, the [O I] 63 μm emission line is self absorbed. Comparing the CO excitation to the InfraRed Astronomical Satellite 60/100 μm ratio and to far infrared luminosity, we find that the CO excitation is more correlated to the far infrared colors. We present cooling budgets for the galaxies and find fine-structure line flux deficits in the [C II], [Si II], [O I], and [C I] lines in the objects with the highest far IR fluxes, but do not observe this for CO 4 <= J upp <= 13. In order to study the heating of the molecular gas, we present a combination of three diagnostic quantities to help determine the dominant heating source. Using the CO excitation, the CO J = 1-0 linewidth, and the active galactic nucleus (AGN) contribution, we conclude that galaxies with large CO linewidths always have high-excitation CO ladders, and often low AGN contributions, suggesting that mechanical heating is important. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  6. THE HERSCHEL COMPREHENSIVE (U)LIRG EMISSION SURVEY (HERCULES): CO LADDERS, FINE STRUCTURE LINES, AND NEUTRAL GAS COOLING

    SciTech Connect

    Rosenberg, M. J. F.; Van der Werf, P. P.; Israel, F. P.; Meijerink, R.; Aalto, S.; Armus, L.; Díaz-Santos, T.; Charmandaris, V.; Evans, A. S.; Fischer, J.; Gao, Y.; González-Alfonso, E.; Greve, T. R.; Harris, A. I.; Henkel, C.; Isaak, K. G.; and others

    2015-03-10

    (Ultra) luminous infrared galaxies ((U)LIRGs) are objects characterized by their extreme infrared (8-1000 μm) luminosities (L {sub LIRG} > 10{sup 11} L {sub ☉} and L {sub ULIRG} > 10{sup 12} L {sub ☉}). The Herschel Comprehensive ULIRG Emission Survey (PI: van der Werf) presents a representative flux-limited sample of 29 (U)LIRGs that spans the full luminosity range of these objects (10{sup 11} L {sub ☉} ≤ L {sub IR} ≤ 10{sup 13} L {sub ☉}). With the Herschel Space Observatory, we observe [C II] 157 μm, [O I] 63 μm, and [O I] 145 μm line emission with Photodetector Array Camera and Spectrometer, CO J = 4-3 through J = 13-12, [C I] 370 μm, and [C I] 609 μm with SPIRE, and low-J CO transitions with ground-based telescopes. The CO ladders of the sample are separated into three classes based on their excitation level. In 13 of the galaxies, the [O I] 63 μm emission line is self absorbed. Comparing the CO excitation to the InfraRed Astronomical Satellite 60/100 μm ratio and to far infrared luminosity, we find that the CO excitation is more correlated to the far infrared colors. We present cooling budgets for the galaxies and find fine-structure line flux deficits in the [C II], [Si II], [O I], and [C I] lines in the objects with the highest far IR fluxes, but do not observe this for CO 4 ≤ J {sub upp} ≤ 13. In order to study the heating of the molecular gas, we present a combination of three diagnostic quantities to help determine the dominant heating source. Using the CO excitation, the CO J = 1-0 linewidth, and the active galactic nucleus (AGN) contribution, we conclude that galaxies with large CO linewidths always have high-excitation CO ladders, and often low AGN contributions, suggesting that mechanical heating is important.

  7. Gamma-ray-selected AGN

    NASA Astrophysics Data System (ADS)

    Giommi, Paolo

    2016-08-01

    The gamma-ray band is the most energetic part of the electromagnetic spectrum. As such it is also where selection effects are most severe, as it can only be reached by the most extreme non-thermal AGN. Blazars, with their emission dominated by non-thermal blue-shifted radiation arising in a relativistic jet pointed in the direction of the observer, naturally satisfy this though requirement. For this reason, albeit these sources are intrisically very rare (orders of magnitude less abundant than radio quiet AGN of the same optical magnitude) they almost completely dominate the extragalactic gamma-ray and very high energy sky. I will discuss the emission of different types of blazars and the selection effects that are at play in the gamma-ray band based on recent results from the current generation of gamma-ray astronomy satellites, ground-based Cherenkov telescopes, and Monte Carlo simulations.

  8. Molecular emission lines in Herbig Ae/Be stars

    NASA Astrophysics Data System (ADS)

    Giannini, T.; Lorenzetti, D.; Tommasi, E.; Nisini, B.; de Benedettini, M.; Barlow, M. J.; Clegg, P. E.; Cohen, M.; Liseau, R.; Molinari, S.; Palla, F.; Pezzuto, S.; Saraceno, P.; Smith, H. A.; Spinoglio, L.; Strafella, F.; White, G. J.

    1999-03-01

    We present the first ISO-LWS observations of the molecular FIR lines in 3 out of a sample of 11 Herbig Ae/Be stars (HAEBE), namely IRAS12496-7650, RCrA and LkHα234. High-J pure rotational CO lines (from Jup = 14 to Jup = 19) have been observed in all the spectra, while two (at 79 μm and 84 μm) and three OH lines (at 71, 79 and 84 μm) have been detected in LkHα234 and RCrA, respectively. For all the sources the molecular emission has been consistently fitted with a Large Velocity Gradient (LVG) model and results as originated in a warm (T >= 200 K) and dense (nH2 >= 105 cm-3) gas. By comparing the observed cooling ratios with models predictions, we find that the FUV radiation is the most probable responsible for line excitation. Shock mechanism contributions can be reasonably ruled out, especially because of the absence in the spectra of any water vapour line, in contrast with the predictions on the molecular emission coming from warm shocked

  9. Unusual broad-line Mg II emitters among luminous galaxies in the baryon oscillation spectroscopic survey

    SciTech Connect

    Roig, Benjamin; Blanton, Michael R.; Ross, Nicholas P.

    2014-02-01

    Many classes of active galactic nuclei (AGNs) have been observed and recorded since the discovery of Seyfert galaxies. In this paper, we examine the sample of luminous galaxies in the Baryon Oscillation Spectroscopic Survey. We find a potentially new observational class of AGNs, one with strong and broad Mg II λ2799 line emission, but very weak emission in other normal indicators of AGN activity, such as the broad-line Hα, Hβ, and the near-ultraviolet AGN continuum, leading to an extreme ratio of broad Hα/Mg II flux relative to normal quasars. Meanwhile, these objects' narrow-line flux ratios reveal AGN narrow-line regions with levels of activity consistent with the Mg II fluxes and in agreement with that of normal quasars. These AGN may represent an extreme case of the Baldwin effect, with very low continuum and high equivalent width relative to typical quasars, but their ratio of broad Mg II to broad Balmer emission remains very unusual. They may also be representative of a class of AGN where the central engine is observed indirectly with scattered light. These galaxies represent a small fraction of the total population of luminous galaxies (≅ 0.1%), but are more likely (about 3.5 times) to have AGN-like nuclear line emission properties than other luminous galaxies. Because Mg II is usually inaccessible for the population of nearby galaxies, there may exist a related population of broad-line Mg II emitters in the local universe which is currently classified as narrow-line emitters (Seyfert 2 galaxies) or low ionization nuclear emission-line regions.

  10. What Quasars Really Look Like: Unification of the Emission and Absorption Line Regions

    NASA Technical Reports Server (NTRS)

    Elvis, Martin

    2000-01-01

    We propose a simple unifying structure for the inner regions of quasars and AGN. This empirically derived model links together the broad absorption line (BALS), the narrow UV/X-ray ionized absorbers, the BELR, and the 5 Compton scattering/fluorescing regions into a single structure. The model also suggests an alternative origin for the large-scale bi-conical outflows. Some other potential implications of this structure are discussed.

  11. Sharp intense line in the bioluminescence emission of the firefly.

    PubMed

    Barua, A Gohain; Sharma, U; Phukan, M; Hazarika, S

    2014-06-01

    Numerous investigations have been carried out on the spectral distribution of the light of different species of fireflies. Here we record the emission spectrum of the Indian species of the firefly Luciola praeusta Kiesenwetter 1874 (Coleoptera : Lampyridae : Luciolinae) on a color film. Green and red color-sectors, with an intense yellow one in between, appear in this spectrum. Intensity profile of this spectrum reveals a hitherto undetected strong narrow yellow line, which lies within the full-width-at-half maximum (FWHM) of the intensity profile. The spectrum recorded in a high-resolution spectrometer confirms the presence of this sharp intense line. This finding lends support to an earlier drawn analogy between the in vivo emission of the firefly and laser light.

  12. The Biases of Optical Line-Ratio Selection for Active Galactic Nuclei and the Intrinsic Relationship between Black Hole Accretion and Galaxy Star Formation

    NASA Astrophysics Data System (ADS)

    Trump, Jonathan R.; Sun, Mouyuan; Zeimann, Gregory R.; Luck, Cuyler; Bridge, Joanna S.; Grier, Catherine J.; Hagen, Alex; Juneau, Stephanie; Montero-Dorta, Antonio; Rosario, David J.; Brandt, W. Niel; Ciardullo, Robin; Schneider, Donald P.

    2015-09-01

    We use 317,000 emission-line galaxies from the Sloan Digital Sky Survey to investigate line-ratio selection of active galactic nuclei (AGNs). In particular, we demonstrate that “star formation (SF) dilution” by H ii regions causes a significant bias against AGN selection in low-mass, blue, star-forming, disk-dominated galaxies. This bias is responsible for the observed preference of AGNs among high-mass, green, moderately star-forming, bulge-dominated hosts. We account for the bias and simulate the intrinsic population of emission-line AGNs using a physically motivated Eddington ratio distribution, intrinsic AGN narrow line region line ratios, a luminosity-dependent {L}{bol}/L[{{O}} {{III}}] bolometric correction, and the observed {M}{BH}-σ relation. These simulations indicate that, in massive ({log}({M}*/{M}⊙ )≳ 10) galaxies, AGN accretion is correlated with specific star formation rate (SFR) but is otherwise uniform with stellar mass. There is some hint of lower black hole occupation in low-mass ({log}({M}*/{M}⊙ )≲ 10) hosts, although our modeling is limited by uncertainties in measuring and interpreting the velocity dispersions of low-mass galaxies. The presence of SF dilution means that AGNs contribute little to the observed strong optical emission lines (e.g., [{{O}} {{III}}] and {{H}}α ) in low-mass and star-forming hosts. However the AGN population recovered by our modeling indicates that feedback by typical (low- to moderate-accretion) low-redshift AGNs has nearly uniform efficiency at all stellar masses, SFRs, and morphologies. Taken together, our characterization of the observational bias and resultant AGN occupation function suggest that AGNs are unlikely to be the dominant source of SF quenching in galaxies, but instead are fueled by the same gas which drives SF activity.

  13. X-Ray and Multiwavelength Insights into the Nature of Weak Emission-line Quasars at Low Redshift

    NASA Astrophysics Data System (ADS)

    Wu, Jianfeng; Brandt, W. N.; Anderson, Scott F.; Diamond-Stanic, Aleksandar M.; Hall, Patrick B.; Plotkin, Richard M.; Schneider, Donald P.; Shemmer, Ohad

    2012-03-01

    We report on the X-ray and multiwavelength properties of 11 radio-quiet quasars with weak or no emission lines identified by the Sloan Digital Sky Survey (SDSS) with redshift z = 0.4-2.5. Our sample was selected from the Plotkin et al. catalog of radio-quiet, weak-featured active galactic nuclei (AGNs). The distribution of relative X-ray brightness for our low-redshift weak-line quasar (WLQ) candidates is significantly different from that of typical radio-quiet quasars, having an excess of X-ray weak sources, but it is consistent with that of high-redshift WLQs. Over half of the low-redshift WLQ candidates are X-ray weak by a factor of >~ 5, compared to a typical SDSS quasar with similar UV/optical luminosity. These X-ray weak sources generally show similar UV emission-line properties to those of the X-ray weak quasar PHL 1811 (weak and blueshifted high-ionization lines, weak semiforbidden lines, and strong UV Fe emission); they may belong to the notable class of PHL 1811 analogs. The average X-ray spectrum of these sources is somewhat harder than that of typical radio-quiet quasars. Several other low-redshift WLQ candidates have normal ratios of X-ray-to-optical/UV flux, and their average X-ray spectral properties are also similar to those of typical radio-quiet quasars. The X-ray weak and X-ray normal WLQ candidates may belong to the same subset of quasars having high-ionization "shielding gas" covering most of the wind-dominated broad emission-line region, but be viewed at different inclinations. The mid-infrared-to-X-ray spectral energy distributions (SEDs) of these sources are generally consistent with those of typical SDSS quasars, showing that they are not likely to be BL Lac objects with relativistically boosted continua and diluted emission lines. The mid-infrared-to-UV SEDs of most radio-quiet weak-featured AGNs without sensitive X-ray coverage (34 objects) are also consistent with those of typical SDSS quasars. However, one source in our X

  14. X-RAY AND MULTIWAVELENGTH INSIGHTS INTO THE NATURE OF WEAK EMISSION-LINE QUASARS AT LOW REDSHIFT

    SciTech Connect

    Wu Jianfeng; Brandt, W. N.; Schneider, Donald P.; Anderson, Scott F.; Diamond-Stanic, Aleksandar M.; Hall, Patrick B.; Plotkin, Richard M.; Shemmer, Ohad

    2012-03-01

    We report on the X-ray and multiwavelength properties of 11 radio-quiet quasars with weak or no emission lines identified by the Sloan Digital Sky Survey (SDSS) with redshift z = 0.4-2.5. Our sample was selected from the Plotkin et al. catalog of radio-quiet, weak-featured active galactic nuclei (AGNs). The distribution of relative X-ray brightness for our low-redshift weak-line quasar (WLQ) candidates is significantly different from that of typical radio-quiet quasars, having an excess of X-ray weak sources, but it is consistent with that of high-redshift WLQs. Over half of the low-redshift WLQ candidates are X-ray weak by a factor of {approx}> 5, compared to a typical SDSS quasar with similar UV/optical luminosity. These X-ray weak sources generally show similar UV emission-line properties to those of the X-ray weak quasar PHL 1811 (weak and blueshifted high-ionization lines, weak semiforbidden lines, and strong UV Fe emission); they may belong to the notable class of PHL 1811 analogs. The average X-ray spectrum of these sources is somewhat harder than that of typical radio-quiet quasars. Several other low-redshift WLQ candidates have normal ratios of X-ray-to-optical/UV flux, and their average X-ray spectral properties are also similar to those of typical radio-quiet quasars. The X-ray weak and X-ray normal WLQ candidates may belong to the same subset of quasars having high-ionization 'shielding gas' covering most of the wind-dominated broad emission-line region, but be viewed at different inclinations. The mid-infrared-to-X-ray spectral energy distributions (SEDs) of these sources are generally consistent with those of typical SDSS quasars, showing that they are not likely to be BL Lac objects with relativistically boosted continua and diluted emission lines. The mid-infrared-to-UV SEDs of most radio-quiet weak-featured AGNs without sensitive X-ray coverage (34 objects) are also consistent with those of typical SDSS quasars. However, one source in our X

  15. The broad emission-line region: the confluence of the outer accretion disc with the inner edge of the dusty torus

    NASA Astrophysics Data System (ADS)

    Goad, M. R.; Korista, K. T.; Ruff, A. J.

    2012-11-01

    We have investigated the observational characteristics of a class of broad emission line region (BLR) geometries that connect the outer accretion disc with the inner edge of the dusty toroidal obscuring region (TOR). We suggest that the BLR consists of photoionized gas of densities which allow for efficient cooling by ultraviolet (UV)/optical emission lines and of incident continuum fluxes which discourage the formation of grains, and that such gas occupies the range of distance and scale height between the continuum-emitting accretion disc and the dusty TOR. As a first approximation, we assume a population of clouds illuminated by ionizing photons from the central source, with the scale height of the illuminated clouds growing with increasing radial distance, forming an effective surface of a 'bowl'. Observer lines of sight which peer into the bowl lead to a Type 1 active galactic nuclei (AGN) spectrum. We assume that the gas dynamics are dominated by gravity, and we include in this model the effects of transverse Doppler shift (TDS), gravitational redshift (GR) and scale-height-dependent macroturbulence. Our simple model reproduces many of the commonly observed phenomena associated with the central regions of AGN, including (i) the shorter than expected continuum-dust delays (geometry), (ii) the absence of response in the core of the optical recombination lines on short time-scales (geometry/photoionization), (iii) an enhanced redwing response on short time-scales (GR and TDS), (iv) the observed differences between the delays for high- and low-ionization lines (photoionization), (v) identifying one of the possible primary contributors to the observed line widths for near face-on systems even for purely transverse motion (GR and TDS), (vi) a mechanism responsible for producing Lorentzian profiles (especially in the Balmer and Mg II emission lines) in low-inclination systems (turbulence), (vii) the absence of significant continuum-emission-line delays between the

  16. Strong optical and UV intermediate-width emission lines in the quasar SDSS J232444.80-094600.3: dust-free and intermediate-density gas at the skin of dusty torus?

    NASA Astrophysics Data System (ADS)

    Li, Zhen-Zhen; Zhou, Hong-Yan; Hao, Lei; Wang, Shu-Fen; Ji, Tuo; Liu, Bo

    2016-09-01

    Emission lines from the broad emission line region (BELR) and the narrow emission line region (NELR) of active galactic nuclei (AGNs) have been extensively studied. However, emission lines are rarely detected between these two regions. We present a detailed analysis of quasar SDSS J232444.80-094600.3 (SDSS J2324-0946), which is remarkable for its strong intermediate-width emission lines (IELs) with FWHM ≈ 1800 km s-1. The IEL component is present in different emission lines, including the permitted lines Lyα λ1216, CIV λ1549, semiforbidden line [CIII] λ1909, and forbidden lines [OIII] λλ4959, 5007. With the aid of photo-ionization models, we found that the IELs are produced by gas with a hydrogen density of nH ˜ 106.2 ˜ 106.3 cm-3, a distance from the central ionizing source of R ˜ 35 - 50 pc, a covering factor of ˜ 6%, and a dust-to-gas ratio of ≤ 4% that of the SMC. We suggest that the strong IELs of this quasar are produced by nearly dust-free and intermediate-density gas located at the skin of the dusty torus. Such strong IELs, which serve as a useful diagnostic, can provide an avenue to study the properties of gas between the BELR and the NELR.

  17. Strong optical and UV intermediate-width emission lines in the quasar SDSS J232444.80–094600.3: dust-free and intermediate-density gas at the skin of dusty torus?

    NASA Astrophysics Data System (ADS)

    Li, Zhen-Zhen; Zhou, Hong-Yan; Hao, Lei; Wang, Shu-Fen; Ji, Tuo; Liu, Bo

    2016-09-01

    Emission lines from the broad emission line region (BELR) and the narrow emission line region (NELR) of active galactic nuclei (AGNs) have been extensively studied. However, emission lines are rarely detected between these two regions. We present a detailed analysis of quasar SDSS J232444.80–094600.3 (SDSS J2324–0946), which is remarkable for its strong intermediate-width emission lines (IELs) with FWHM ≈ 1800 km s‑1. The IEL component is present in different emission lines, including the permitted lines Lyα λ1216, CIV λ1549, semiforbidden line [CIII] λ1909, and forbidden lines [OIII] λλ4959, 5007. With the aid of photo-ionization models, we found that the IELs are produced by gas with a hydrogen density of nH ∼ 106.2 ∼ 106.3 cm‑3, a distance from the central ionizing source of R ∼ 35 – 50 pc, a covering factor of ∼ 6%, and a dust-to-gas ratio of ≤ 4% that of the SMC. We suggest that the strong IELs of this quasar are produced by nearly dust-free and intermediate-density gas located at the skin of the dusty torus. Such strong IELs, which serve as a useful diagnostic, can provide an avenue to study the properties of gas between the BELR and the NELR.

  18. Strong optical and UV intermediate-width emission lines in the quasar SDSS J232444.80–094600.3: dust-free and intermediate-density gas at the skin of dusty torus?

    NASA Astrophysics Data System (ADS)

    Li, Zhen-Zhen; Zhou, Hong-Yan; Hao, Lei; Wang, Shu-Fen; Ji, Tuo; Liu, Bo

    2016-09-01

    Emission lines from the broad emission line region (BELR) and the narrow emission line region (NELR) of active galactic nuclei (AGNs) have been extensively studied. However, emission lines are rarely detected between these two regions. We present a detailed analysis of quasar SDSS J232444.80–094600.3 (SDSS J2324–0946), which is remarkable for its strong intermediate-width emission lines (IELs) with FWHM ≈ 1800 km s‑1. The IEL component is present in different emission lines, including the permitted lines Lyα λ1216, CIV λ1549, semiforbidden line [CIII] λ1909, and forbidden lines [OIII] λλ4959, 5007. With the aid of photo-ionization models, we found that the IELs are produced by gas with a hydrogen density of nH ˜ 106.2 ˜ 106.3 cm‑3, a distance from the central ionizing source of R ˜ 35 – 50 pc, a covering factor of ˜ 6%, and a dust-to-gas ratio of ≤ 4% that of the SMC. We suggest that the strong IELs of this quasar are produced by nearly dust-free and intermediate-density gas located at the skin of the dusty torus. Such strong IELs, which serve as a useful diagnostic, can provide an avenue to study the properties of gas between the BELR and the NELR.

  19. LY-alpha Line Emission in a Field of Super-Clustered Damped LY-alpha Absorbers

    NASA Astrophysics Data System (ADS)

    Møller, Palle; Warren, Stephen J.

    1993-12-01

    The quasar pair Q2138-4427 and Q2139-4434 is separated by 8 arcmin on the sky (~ 6 Mpc), and they have correlated damped \\lya absorption (DLA) at two redshifts, z=2.380 and z=2.853 (Francis, P. J., and Hewett, P. C., 1993, AJ 105, 1633). On three nights in September 1993 we imaged the field of Q2138-4427 in B, I, and a narrow band tuned to the DLA at z=2.853. The observations were carried out with the ESO 3.6m telescope. We find two emission line candidates in the field. The two candidates have line fluxes similar to the three sources found in the field of Q0528-250 (M{\\o}ller, P., and Warren, S. J., 1993, \\aa 270, 43) but they are much brighter in the continuum. The two candidates are lying quite far from the quasar, so even if they are spectroscopically confirmed to be \\lya emitters, they are unlikely to be identified with the absorber. Their continuum fluxes make them more likely to be either OII emitters at low redshift, or high redshift AGNs associated with the super-cluster structure reported by Francis and Hewett. \\lya emission sources similar to the ones detected in the field of Q0528-250 are not seen. A comparison of these new results with our previous detections will allow us to draw general conclusions on the nature of the damped systems.

  20. Exploring AGNs in the Local Universe through High Angular Resolution Spectroscopy and Optical Variability Monitoring

    NASA Astrophysics Data System (ADS)

    Walsh, Jonelle L.

    This dissertation presents the results of several observational projects designed to explore AGNs, on scales of about 100 pc and smaller, in nearby galaxies. High angular resolution spectroscopy acquired from HST STIS and Keck LGS AO OSIRIS observations are used to study the kinematic structure of gas disks and stars on scales comparable to the gravitational sphere of influence of the supermassive black hole. Specifically, I use multi-slit STIS data of low-luminosity AGNs to map out the emission-line kinematics, and to look for regularly rotating velocity fields suitable for future gas dynamical black hole mass measurements. The HST data is further useful for searching for electron-density gradients and for examining how the emission-line velocity dispersion varies as a function of aperture size. In another project, I aim to resolve a discrepancy between two previous gas dynamical measurements of the black hole in the elliptical galaxy M84. I perform new measurements of the gas kinematics from archival multi-slit STIS data, and carry out a more comprehensive dynamical model of the emission-line disk than had been previously attempted. With the most recent project, I measure high-resolution stellar kinematics from LGS AO OSIRIS data and large-scale kinematics from long-slit LRIS data of the S0 galaxy NGC 3998. Using triaxial orbit-based stellar dynamical models, I determine the black hole mass. The stellar dynamical value is then compared to a previous gas dynamical determination in order to test the consistency between these two main mass measurement methods. In addition to using high spatial resolution spectroscopy, AGN variability can be used to probe the inner regions of AGNs. The Lick AGN Monitoring Project targeted 12 galaxies expected to harbor low-mass black holes. Through reverberation mapping, the collaboration measured the masses of nine black holes, and learned about the geometry and kinematics of the broad-line region in several of the objects. I

  1. Continuum and line emission of flares on red dwarf stars

    NASA Astrophysics Data System (ADS)

    Morchenko, E.; Bychkov, K.; Livshits, M.

    2015-06-01

    The emission spectrum has been calculated of a homogeneous pure hydrogen layer, which parameters are typical for a flare on a red dwarf. The ionization and excitation states were determined by the solution of steady-state equations taking into account the continuum and all discrete hydrogen levels. We consider the following elementary processes: electron-impact transitions, spontaneous and induced radiative transitions, and ionization by the bremsstrahlung and recombination radiation of the layer itself. The Biberman-Holstein approximation was used to calculate the scattering of line radiation. Asymptotic formulae for the escape probability are obtained for a symmetric line profile taking into account the Stark and Doppler effects. The approximation for the core of the H- α line by a Gaussian curve has been substantiated.

  2. Chandra X-Ray and Hubble Space Telescope Imaging of Optically Selected Kiloparsec-scale Binary Active Galactic Nuclei. II. Host Galaxy Morphology and AGN Activity

    NASA Astrophysics Data System (ADS)

    Shangguan, Jinyi; Liu, Xin; Ho, Luis C.; Shen, Yue; Peng, Chien Y.; Greene, Jenny E.; Strauss, Michael A.

    2016-05-01

    Binary active galactic nuclei (AGNs) provide clues to how gas-rich mergers trigger and fuel AGNs and how supermassive black hole (SMBH) pairs evolve in a gas-rich environment. While significant effort has been invested in their identification, the detailed properties of binary AGNs and their host galaxies are still poorly constrained. In a companion paper, we examined the nature of ionizing sources in the double nuclei of four kiloparsec-scale binary AGNs with redshifts between 0.1 and 0.2. Here, we present their host galaxy morphology based on F336W (U-band) and F105W (Y-band) images taken by the Wide Field Camera 3 on board the Hubble Space Telescope. Our targets have double-peaked narrow emission lines and were confirmed to host binary AGNs with follow-up observations. We find that kiloparsec-scale binary AGNs occur in galaxy mergers with diverse morphological types. There are three major mergers with intermediate morphologies and a minor merger with a dominant disk component. We estimate the masses of the SMBHs from their host bulge stellar masses and obtain Eddington ratios for each AGN. Compared with a representative control sample drawn at the same redshift and stellar mass, the AGN luminosities and Eddington ratios of our binary AGNs are similar to those of single AGNs. The U - Y color maps indicate that clumpy star-forming regions could significantly affect the X-ray detection of binary AGNs, e.g., the hardness ratio. Considering the weak X-ray emission in AGNs triggered in merger systems, we suggest that samples of X-ray-selected AGNs may be biased against gas-rich mergers. Based, in part, on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program number GO 12363.

  3. Chandra X-Ray and Hubble Space Telescope Imaging of Optically Selected Kiloparsec-scale Binary Active Galactic Nuclei. II. Host Galaxy Morphology and AGN Activity

    NASA Astrophysics Data System (ADS)

    Shangguan, Jinyi; Liu, Xin; Ho, Luis C.; Shen, Yue; Peng, Chien Y.; Greene, Jenny E.; Strauss, Michael A.

    2016-05-01

    Binary active galactic nuclei (AGNs) provide clues to how gas-rich mergers trigger and fuel AGNs and how supermassive black hole (SMBH) pairs evolve in a gas-rich environment. While significant effort has been invested in their identification, the detailed properties of binary AGNs and their host galaxies are still poorly constrained. In a companion paper, we examined the nature of ionizing sources in the double nuclei of four kiloparsec-scale binary AGNs with redshifts between 0.1 and 0.2. Here, we present their host galaxy morphology based on F336W (U-band) and F105W (Y-band) images taken by the Wide Field Camera 3 on board the Hubble Space Telescope. Our targets have double-peaked narrow emission lines and were confirmed to host binary AGNs with follow-up observations. We find that kiloparsec-scale binary AGNs occur in galaxy mergers with diverse morphological types. There are three major mergers with intermediate morphologies and a minor merger with a dominant disk component. We estimate the masses of the SMBHs from their host bulge stellar masses and obtain Eddington ratios for each AGN. Compared with a representative control sample drawn at the same redshift and stellar mass, the AGN luminosities and Eddington ratios of our binary AGNs are similar to those of single AGNs. The U ‑ Y color maps indicate that clumpy star-forming regions could significantly affect the X-ray detection of binary AGNs, e.g., the hardness ratio. Considering the weak X-ray emission in AGNs triggered in merger systems, we suggest that samples of X-ray-selected AGNs may be biased against gas-rich mergers. Based, in part, on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program number GO 12363.

  4. ESTIMATION OF RELATIVISTIC ACCRETION DISK PARAMETERS FROM IRON LINE EMISSION

    SciTech Connect

    V. PARIEV; B. BROMLEY; W. MILLER

    2001-03-01

    The observed iron K{alpha} fluorescence lines in Seyfert I galaxies provide strong evidence for an accretion disk near a supermassive black hole as a source of the emission. Here we present an analysis of the geometrical and kinematic properties of the disk based on the extreme frequency shifts of a line profile as determined by measurable flux in both the red and blue wings. The edges of the line are insensitive to the distribution of the X-ray flux over the disk, and hence provide a robust alternative to profile fitting of disk parameters. Our approach yields new, strong bounds on the inclination angle of the disk and the location of the emitting region. We apply our method to interpret observational data from MCG-6-30-15 and find that the commonly assumed inclination 30{degree} for the accretion disk in MCG-6-30-15 is inconsistent with the position of the blue edge of the line at a 3{sigma} level. A thick turbulent disk model or the presence of highly ionized iron may reconcile the bounds on inclination from the line edges with the full line profile fits based on simple, geometrically thin disk models. The bounds on the innermost radius of disk emission indicate that the black hole in MCG-6-30-15 is rotating faster than 30% of theoretical maximum. When applied to data from NGC 4151, our method gives bounds on the inclination angle of the X-ray emitting inner disk of 50 {+-} 10{degree}, consistent with the presence of an ionization cone grazing the disk as proposed by Pedlar et al. (1993). The frequency extrema analysis also provides limits to the innermost disk radius in another Seyfert 1 galaxy, NGC 3516, and is suggestive of a thick disk model.

  5. The importance of warm, AGN-driven outflows in the nuclear regions of nearby ULIRGs

    NASA Astrophysics Data System (ADS)

    Rodríguez Zaurín, J.; Tadhunter, C. N.; Rose, M.; Holt, J.

    2013-06-01

    We present an optical spectroscopic study of a 90 per cent complete sample of nearby ULIRGs (z < 0.175) with optical Seyfert nuclei, with the aim of investigating the nature of the near-nuclear (r ≲ 3.5 kpc) warm gas outflows. A high proportion (94 per cent) of our sample show disturbed emission line kinematics in the form of broad (FWHM > 500 km s-1) and/or strongly blueshifted (ΔV < -150 km s-1) emission line components. This proportion is significantly higher than found in a comparison sample of nearby ultraluminous infrared galaxies (ULIRGs) that lack optical Seyfert nuclei (19 per cent). We also find evidence that the emission line kinematics of the Sy-ULIRGs are more highly disturbed than those of samples of non-ULIRG Seyferts and Palomar-Green quasars in the sense that, on average, their [O III] λλ5007, 4959 emission lines are broader and more asymmetric. The Sy-ULIRG sample encompasses a wide diversity of emission line profiles. In most individual objects, we are able to fit the profiles of all the emission lines of different ionization with a kinematic model derived from the strong [O III] λλ4959, 5007 lines, using between two and five Gaussian components. From these fits, we derive diagnostic line ratios that are used to investigate the ionization mechanisms for the different kinematic components. We show that, in general, the line ratios are consistent with gas of supersolar abundance photoionized by a combination of AGN and starburst activity, with an increasing contribution from the AGN with increasing FWHM of the individual kinematic components, and the AGN contribution dominating for the broadest components. However, shock ionization cannot be ruled out in some cases. Our derived upper limits on the mass outflows rates and kinetic powers of the emission line outflows show that they can be as energetically significant as the neutral and molecular outflows in ULIRGs - consistent with the requirements of the hydrodynamic simulations that include

  6. A CENSUS OF BROAD-LINE ACTIVE GALACTIC NUCLEI IN NEARBY GALAXIES: COEVAL STAR FORMATION AND RAPID BLACK HOLE GROWTH

    SciTech Connect

    Trump, Jonathan R.; Fang, Jerome J.; Faber, S. M.; Koo, David C.; Kocevski, Dale D.

    2013-02-15

    We present the first quantified, statistical map of broad-line active galactic nucleus (AGN) frequency with host galaxy color and stellar mass in nearby (0.01 < z < 0.11) galaxies. Aperture photometry and z-band concentration measurements from the Sloan Digital Sky Survey are used to disentangle AGN and galaxy emission, resulting in estimates of uncontaminated galaxy rest-frame color, luminosity, and stellar mass. Broad-line AGNs are distributed throughout the blue cloud and green valley at a given stellar mass, and are much rarer in quiescent (red sequence) galaxies. This is in contrast to the published host galaxy properties of weaker narrow-line AGNs, indicating that broad-line AGNs occur during a different phase in galaxy evolution. More luminous broad-line AGNs have bluer host galaxies, even at fixed mass, suggesting that the same processes that fuel nuclear activity also efficiently form stars. The data favor processes that simultaneously fuel both star formation activity and rapid supermassive black hole accretion. If AGNs cause feedback on their host galaxies in the nearby universe, the evidence of galaxy-wide quenching must be delayed until after the broad-line AGN phase.

  7. Search for extended γ-ray emission around AGN with H.E.S.S. and Fermi-LAT

    NASA Astrophysics Data System (ADS)

    H. E. S. S. Collaboration; Abramowski, A.; Aharonian, F.; Ait Benkhali, F.; Akhperjanian, A. G.; Angüner, E.; Anton, G.; Backes, M.; 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.; 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-Atäı, 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.; Lemie`re, A.; Lemoine-Goumard, M.; Lenain, J.-P.; 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.; Odaka, H.; 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.; Reichardt, I.; 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.; 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.; Wagner, R. M.; Ward, M.; Weidinger, M.; Weitzel, Q.; White, R.; Wierzcholska, A.; Willmann, P.; Wörnlein, A.; Wouters, D.; Yang, R.; Zabalza, V.; Zacharias, M.; Zdziarski, A. A.; Zech, A.; Zechlin, H.-S.; Malyshev, D.

    2014-02-01

    Context. Very-high-energy (VHE; E > 100 GeV) γ-ray emission from blazars inevitably gives rise to electron-positron pair production through the interaction of these γ-rays with the extragalactic background light (EBL). Depending on the magnetic fields in the proximity of the source, the cascade initiated from pair production can result in either an isotropic halo around an initially beamed source or a magnetically broadened cascade flux. Aims: Both extended pair-halo (PH) and magnetically broadened cascade (MBC) emission from regions surrounding the blazars 1ES 1101-232, 1ES 0229+200, and PKS 2155-304 were searched for using VHE γ-ray data taken with the High Energy Stereoscopic System (H.E.S.S.) and high-energy (HE; 100 MeV < E < 100 GeV) γ-ray data with the Fermi Large Area Telescope (LAT). Methods: By comparing the angular distributions of the reconstructed γ-ray events to the angular profiles calculated from detailed theoretical models, the presence of PH and MBC was investigated. Results: Upper limits on the extended emission around 1ES 1101-232, 1ES 0229+200, and PKS 2155-304 are found to be at a level of a few per cent of the Crab nebula flux above 1 TeV, depending on the assumed photon index of the cascade emission. Assuming strong extra-Galactic magnetic field (EGMF) values, >10-12 G, this limits the production of pair haloes developing from electromagnetic cascades. For weaker magnetic fields, in which electromagnetic cascades would result in MBCs, EGMF strengths in the range (0.3-3)× 10-15 G were excluded for PKS 2155-304 at the 99% confidence level, under the assumption of a 1 Mpc coherence length.

  8. Studying Cosmic Dawn and Emission Line Galaxies with WFIRST-AFTA

    NASA Astrophysics Data System (ADS)

    Rhoads, James

    WFIRST-AFTA will provide a wealth of near-infrared spectra and imaging for 100s of millions of galaxies at redshifts z=1-3. While the primary aim of the WFIRST spectroscopic survey is to determine the geometry of the universe, these data will revolutionize our understanding of galaxy evolution at the peak epoch of star formationactivity. Understanding the galaxy spectra will not only help us address major issues in galaxy formation and evolution, but will also reduce random and systematic errors in the redshift determination for BAO and weak lensing experiments. We offer extensive experience of studying line emitters from z=0.3-7, using both slitless spectroscopy on HST and narrow-band imaging from the ground, together with higher resolution ground-based spectroscopic followup. The HST slitless spectrographs are the best analogs to the WFIRST-AFTA spectrograph in spectral and spatial resolution, and in operations mode. There are unique challenges in slitless spectroscopy, and our extensive experience will help to meet them. The three top-level science goals given by the "New Worlds, New Horizons" decadal survey report are Cosmic Dawn, New Worlds, and the Physics of the Universe. WFIRST's core mission objectives explicitly include the Physics of the Universe (through dark energy surveys) and New Worlds (through microlensing and perhaps coronographic observations). WFIRST-AFTA can make equally powerful contributions to the study of Cosmic Dawn. Its sensitivity, spatial resolution, and wide field of view make it uniquely powerful for studying the first faint, highly redshifted galaxies. We propose to: 1) Apply this accumulated expertise, software and existing HST data to help with the predictions, simulations, and detailed planning and possible optimization of spectroscopic observations. 2) Detail how studies of Emission Line Galaxies (ELGs) between z=1-3 will address outstanding questions in galaxy evolution and assembly at the peak of star-formation and AGN activity

  9. LINE EMISSION FROM RADIATION-PRESSURIZED H II REGIONS. I. INTERNAL STRUCTURE AND LINE RATIOS

    SciTech Connect

    Yeh, Sherry C. C.; Matzner, Christopher D.; Verdolini, Silvia; Tielens, Alexander G. G. M.; Krumholz, Mark R.

    2013-05-20

    The emission line ratios [O III] {lambda}5007/H{beta} and [N II] {lambda}6584/H{alpha} have been adopted as an empirical way to distinguish between the fundamentally different mechanisms of ionization in emission-line galaxies. However, detailed interpretation of these diagnostics requires calculations of the internal structure of the emitting H II regions, and these calculations depend on the assumptions one makes about the relative importance of radiation pressure and stellar winds. In this paper, we construct a grid of quasi-static H II region models to explore how choices about these parameters alter H II regions' emission line ratios. We find that when radiation pressure is included in our models, H II regions reach a saturation point beyond which further increase in the luminosity of the driving stars does not produce any further increase in effective ionization parameter, and thus does not yield any further alteration in an H II region's line ratio. We also show that if stellar winds are assumed to be strong, the maximum possible ionization parameter is quite low. As a result of this effect, it is inconsistent to simultaneously assume that H II regions are wind-blown bubbles and that they have high ionization parameters; some popular H II region models suffer from this inconsistency. Our work in this paper provides a foundation for a companion paper in which we embed the model grids we compute here within a population synthesis code that enables us to compute the integrated line emission from galactic populations of H II regions.

  10. CO Emission from Low-Redshift QSO Absorption Line Systems

    NASA Astrophysics Data System (ADS)

    Walker, C. E.; Bechtold, J.; Black, J. H.

    1994-12-01

    By studying the physical conditions in galaxies at different redshifts, we can begin to understand the evolutionary process of starformation from early epochs to the present. Such studies have been performed at optical and centimeter wavelengths for a number of years. Due to advances in receiver and telescope technology at millimeter and submillimeter wavelengths, molecular line studies have recently been performed toward high redshift absorption line systems. Observations of the mm/submm CO lines in these very young galaxies provide a way to investigate abundances of and conditions in potential starforming material. CO provides some of the strongest emission lines associated with star formation in nearby disk galaxies. Here we report the detection of CO in emission toward 4 galaxies at redshifts of 0.02 to 0.40. From these observations we are able to compute the molecular mass of the starforming material. Studies of starformation in galaxies at low to mid-redshift ranges are important, because these systems represent a transitional phase between starformation at early epochs and the present. Our recent detections of CO emission indicate total molecular masses in three of the galaxies to be a few times 10(9) Msun, using the ``standard conversion factor'' for molecular hydrogen column density to integrated CO intensity ratio (N(H_2)/Ico) and an H_o=75km/s/Mpc and q_o= 0.5. The fourth system, the z=0.40 21 cm absorber toward PKS 1229-021, has a molecular mass of ~ 10(11) M_sunh(-2) . Together with data at other wavelengths, the z=0.40 absorber may be a in pre-starburst phase. All four of our sources were selected to be metal line systems (with high HI column densities) and possess strong FIR fluxes detected by IRAS at 60 and/or 100{microns }. The source possessing the brightest FIR emission among the four is the z=0.05 21 cm absorber toward S4 0248+43. The total observed FIR luminosity for this source is LFIR =3.0x10E11 Lsun. Taking into account its luminosity and

  11. Sodium D-line emission from Io - Comparison of observed and theoretical line profiles

    NASA Technical Reports Server (NTRS)

    Carlson, R. W.; Matson, D. L.; Johnson, T. V.; Bergstralh, J. T.

    1978-01-01

    High-resolution spectra of the D-line profiles have been obtained for Io's sodium emission cloud. These lines, which are produced through resonance scattering of sunlight, are broad and asymmetric and can be used to infer source and dynamical properties of the sodium cloud. In this paper we compare line profile data with theoretical line shapes computed for several assumed initial velocity distributions corresponding to various source mechanisms. We also examine the consequences of source distributions which are nonuniform over the surface of Io. It is found that the experimental data are compatible with escape of sodium atoms from the leading hemisphere of Io and with velocity distributions characteristic of sputtering processes. Thermal escape and simple models of plasma sweeping are found to be incompatible with the observations.

  12. 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.

  13. Accretion disc-corona and jet emission from the radio-loud narrow-line Seyfert 1 galaxy RX J1633.3+4719

    NASA Astrophysics Data System (ADS)

    Mallick, Labani; Dewangan, G. C.; Gandhi, P.; Misra, R.; Kembhavi, A. K.

    2016-08-01

    We perform X-ray/ultraviolet (UV) spectral and X-ray variability studies of the radio-loud narrow-line Seyfert 1 (NLS1) galaxy RX J1633.3+4719 using XMM-Newton and Suzaku observations from 2011 and 2012. The 0.3-10 keV spectra consist of an ultrasoft component described by an accretion disc blackbody (kT_in = 39.6^{+11.2}_{-5.5} eV) and a power law due to the thermal Comptonization (Γ = 1.96^{+0.24}_{-0.31}) of the disc emission. The disc temperature inferred from the soft excess is at least a factor of 2 lower than that found for the canonical soft excess emission from radio-quiet NLS1s. The UV spectrum is described by a power law with photon index 3.05^{+0.56}_{-0.33}. The observed UV emission is too strong to arise from the accretion disc or the host galaxy, but can be attributed to a jet. The X-ray emission from RX J1633.3+4719 is variable with fractional variability amplitude Fvar = 13.5 ± 1.0 per cent. In contrast to radio-quiet active galactic nuclei (AGN), X-ray emission from the source becomes harder with increasing flux. The fractional rms variability increases with energy and the rms spectrum is well described by a constant disc component and a variable power-law continuum with the normalization and photon index being anticorrelated. Such spectral variability cannot be caused by variations in the absorption and must be intrinsic to the hot corona. Our finding of possible evidence for emission from the inner accretion disc, jet and hot corona from RX J1633.3+4719 in the optical to X-ray bands makes this object an ideal target to probe the disc-jet connection in AGN.

  14. Emission-line objects projected upon the galactic bulge.

    PubMed

    Herbig, G H

    1969-08-01

    Low-dispersion slit spectrograms have been obtained of 34 faint objects that lie in the direction of the galactic bulge and have the Halpha line in emission upon a detectable continuum. Eleven of these are certain or probable symbiotic stars. A rough comparison with R CrB stars in the same area suggests that these brightest symbiotics in the bulge have in the mean M(v) approximately -3 to -4, which suggest Population II red giants rather than conventional Population I M-type objects. The sample also contains a number of hot stars having H and [O II] or [O III] in emission, as well as four conventional Be stars, and six certain or possible planetary nebulae. PMID:16578699

  15. Narrowband emission line imaging spectrometry using Savart plates

    NASA Astrophysics Data System (ADS)

    Maione, Bryan; Brickson, Leandra; Kudenov, Michael; Escuti, Michael

    2016-05-01

    Polarization spatial heterodyne interferometry (PSHI) allows for the development of compact, vibration insensitive, high spectral resolution sensors. Introducing the imaging qualities of a lenslet array extends the advantages of PSHI to imaging interferometers. The use of Savart plates enables a birefringent interferometer that obtains higher spectral resolution with fewer optical aberrations when compared to alternative designs. In this paper, we describe the design, construction, calibration and validation of a narrowband emission line imaging spectrometer (NELIS), based on Savart plates and liquid crystal polarization gratings, along with its associated theoretical model. This sensor is advantageous for spectral imaging in the areas of remote sensing, biomedical imaging and machine vision.

  16. Shocked POststarbust Galaxy Survey. I. Candidate Post-starbust Galaxies with Emission Line Ratios Consistent with Shocks

    NASA Astrophysics Data System (ADS)

    Alatalo, Katherine; Cales, Sabrina L.; Rich, Jeffrey A.; Appleton, Philip N.; Kewley, Lisa J.; Lacy, Mark; Lanz, Lauranne; Medling, Anne M.; Nyland, Kristina

    2016-06-01

    There are many mechanisms by which galaxies can transform from blue, star-forming spirals, to red, quiescent early-type galaxies, but our current census of them does not form a complete picture. Recent observations of nearby case studies have identified a population of galaxies that quench “quietly.” Traditional poststarburst searches seem to catch galaxies only after they have quenched and transformed, and thus miss any objects with additional ionization mechanisms exciting the remaining gas. The Shocked POststarburst Galaxy Survey (SPOGS) aims to identify transforming galaxies, in which the nebular lines are excited via shocks instead of through star formation processes. Utilizing the Oh-Sarzi-Schawinski-Yi (OSSY) measurements on the Sloan Digital Sky Survey Data Release 7 catalog, we applied Balmer absorption and shock boundary criteria to identify 1067 SPOG candidates (SPOGs*) within z = 0.2. SPOGs* represent 0.2% of the OSSY sample galaxies that exceed the continuum signal-to-noise cut (and 0.7% of the emission line galaxy sample). SPOGs* colors suggest that they are in an earlier phase of transition than OSSY galaxies that meet an “E+A” selection. SPOGs* have a 13% 1.4 GHz detection rate from the Faint Images of the Radio Sky at Twenty Centimeters Survey, higher than most other subsamples, and comparable only to low-ionization nuclear emission line region hosts, suggestive of the presence of active galactic nuclei (AGNs). SPOGs* also have stronger Na i D absorption than predicted from the stellar population, suggestive of cool gas being driven out in galactic winds. It appears that SPOGs* represent an earlier phase in galaxy transformation than traditionally selected poststarburst galaxies, and that a large proportion of SPOGs* also have properties consistent with disruption of their interstellar media, a key component to galaxy transformation. It is likely that many of the known pathways to transformation undergo a SPOG phase. Studying this sample of

  17. The Hubble Space Telescope Quasar Absorption Line Key Project. 10: Galactic H I 21 centimeter emission toward 143 quasars and active Galactic nuclei

    NASA Technical Reports Server (NTRS)

    Lockman, Felix J.; Savage, Blair D.

    1995-01-01

    Sensitive H I 21 cm emission line spectra have been measured for the directions to 143 quasars and active galactic nuclei (AGNs) chosen from the observing lists for the Hubble Space Telescope (HST) Quasar Absorption Line Key Project. Narrow-band and wide-band data were obtained with the National Radio Astronomy Observatory (NRAO) 43 m radio telescope for each object. The narrow-band data have a velocity resolution of 1 km/s, extend from -220 to +170 km/s, and are corrected for stray 21 cm radiation. The wide-band data have a resolution of 4 km/s and extend from -1000 to +1000 km/s. The data are important for the interpretation of ultraviolet absorption lines near zero redshift in Key Project spectra. Twenty-two percent of the quasars lie behind Galactic high-velocity H I clouds with absolute value of V(sub LSR) greater than 100 km/s whose presence can increase the equivalent width of interstellar absorption lines significantly. This paper contains the emission spectra and measures of the H I velocities and column densities along the sight line to each quasar. We discuss how the measurements can be used to estimate the visual and ultraviolet extinction toward each quasar and to predict the approximate strength of the strong ultraviolet resonance lines of neutral gas species in the HST Key Project spectra.

  18. Non-thermal emission from standing relativistic shocks: an application to red giant winds interacting with AGN jets

    NASA Astrophysics Data System (ADS)

    Bosch-Ramon, V.

    2015-03-01

    Context. Galactic and extragalactic relativistic jets are surrounded by rich environments that are full of moving objects, such as stars and dense medium inhomogeneities. These objects can enter into the jets and generate shocks and non-thermal emission. Aims: We characterize the emitting properties of the downstream region of a standing shock formed due to the interaction of a relativistic jet with an obstacle. We focus on the case of red giants interacting with an extragalactic jet. Methods: We perform relativistic axisymmetric hydrodynamical simulations of a relativistic jet meeting an obstacle of very large inertia. The results are interpreted in the framework of a red giant whose dense and slow wind interacts with the jet of an active galactic nucleus. Assuming that particles are accelerated in the standing shock generated in the jet as it impacts the red giant wind, we compute the non-thermal particle distribution, the Doppler boosting enhancement, and the non-thermal luminosity in gamma rays. Results: The available non-thermal energy from jet-obstacle interactions is potentially enhanced by a factor of ~100 when accounting for the whole surface of the shock induced by the obstacle, instead of just the obstacle section. The observer gamma-ray luminosity, including the effective obstacle size, the flow velocity and Doppler boosting effects, can be ~300 (γj/10)2 times higher than when the emitting flow is assumed at rest and only the obstacle section is considered, where γj is the jet Lorentz factor. For a whole population of red giants inside the jet of an active galactic nucleus, the predicted persistent gamma-ray luminosities may be potentially detectable for a jet pointing approximately to the observer. Conclusions: Obstacles interacting with relativistic outflows, for instance clouds and populations of stars for extragalactic jets, or stellar wind inhomogeneities in microquasar jets and in winds of pulsars in binaries, should be taken into account when

  19. 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.

  20. THE ORIGIN OF [O II] EMISSION IN RECENTLY QUENCHED ACTIVE GALACTIC NUCLEUS HOSTS

    SciTech Connect

    Kocevski, Dale D.; Lemaux, Brian C.; Lubin, Lori M.; Shapley, Alice E.; Gal, Roy R.; Squires, Gordon K.

    2011-08-20

    We have employed emission-line diagnostics derived from DEIMOS and NIRSPEC spectroscopy to determine the origin of the [O II] emission line observed in six active galactic nucleus (AGN) hosts at z {approx} 0.9. These galaxies are a subsample of AGN hosts detected in the Cl1604 supercluster that exhibit strong Balmer absorption lines in their spectra and appear to be in a post-starburst or post-quenched phase, if not for their [O II] emission. Examining the flux ratio of the [N II] to H{alpha} lines, we find that in five of the six hosts the dominant source of ionizing flux is AGN continuum emission. Furthermore, we find that four of the six galaxies have over twice the [O II] line luminosity that could be generated by star formation alone given their H{alpha} line luminosities. This strongly suggests that AGN-excited narrow-line emission is contaminating the [O II] line flux. A comparison of star formation rates calculated from extinction-corrected [O II] and H{alpha} line luminosities indicates that the former yields a five-fold overestimate of the current activity in these galaxies. Our findings reveal the [O II] line to be a poor indicator of star formation activity in a majority of these moderate-luminosity Seyferts. This result bolsters our previous findings that an increased fraction of AGN at high redshifts is hosted by galaxies in a post-starburst phase. The relatively high fraction of AGN hosts in the Cl1604 supercluster that show signs of recently truncated star formation activity may suggest that AGN feedback plays an increasingly important role in suppressing ongoing activity in large-scale structures at high redshift.

  1. The Evolution of Obscuration in AGN

    NASA Astrophysics Data System (ADS)

    Treister, Ezequiel; Urry, M.; Virani, S.

    2006-09-01

    One fundamental ingredient in our understanding of the AGN population is the ratio of obscured to unobscured AGN and whether this ratio depends on other parameters like intrinsic luminosity or redshift. Observationally, deep X-ray surveys found that the obscured AGN fraction depends on luminosity. However, the dependence on redshift is less clear. In this work, we constructed the largest sample to date of AGN selected in hard X-rays, containing a total of 1229 sources, 631 of them obscured, with a high spectroscopic completeness in order to study the possible dependence of the fraction of obscured sources with redshift and/or luminosity. We confirm that this fraction decreases with increasing luminosity as previously reported and found that at the same time it increases with increasing redshift. This is the first time that this evolution is significantly detected using only optical spectroscopy to separate obscured and unobscured AGN. Additionally, we use the spectral shape and intensity of the X-ray background as a separate constraint on the evolution of the obscured AGN fraction finding consistent results. This result can be interpreted as an evolution in the location of the obscuration, from the central parsec-scale region (the torus) at low redshift to kiloparsec scales (the host galaxy) at high redshift, as it is known that most galaxies contained more dust in the past. Using these results, we calculate the integrated bolometric AGN emission finding it to be at most 5% of the total extragalactic light. Hence, while AGN contribute most of the light at X-ray wavelengths, they constitute only a small fraction of the integrated extragalactic light. We thank the support of the Centro de Astrof\\'{\\i}sica FONDAP and from NASA/{\\it INTEGRAL} grant NNG05GM79G.

  2. Far-Infrared Water Line Emissions from Circumstellar Outflows

    NASA Technical Reports Server (NTRS)

    Chen, Wesley; Neufeld, David A.

    1995-01-01

    We have modeled the far-infrared water line emission expected from circumstellar outflows from oxygen-rich late-type stars, as a function of the mass-loss rate and the terminal outflow velocity. For each mass-loss rate and terminal outflow velocity considered, we computed self-consistently the gas density, temperature, outflow velocity, and water abundance as a function of distance from the star. We then used an escape probability method to solve for the equilibrium level populations of 80 rotational states of water and thereby obtained predictions for the luminosity of a large number of far-infrared rotational transitions of water. In common with previous models, our model predicts that water will be copiously produced in the warm circumstellar gas and that water rotational emission will dominate the radiative cooling. However, our use of a realistic radiative cooling function for water leads to a lower gas temperature than that predicted in previous models. Our predictions for the far-infrared water line luminosities are consequently significantly smaller than those obtained in previous studies. Observations to be carried out by the Infrared Space Observatory will provide a crucial test of the models presented here.

  3. Analysis and Interpretation of Astrophysical Optical Emission-Line Spectra

    NASA Astrophysics Data System (ADS)

    Loubser, S. I.

    This study consists of a quantitative optical emission-line analysis of spectra from five blue compact galaxies (Zw 0855, Mrk 1267, II Zw 33, Tol 2 & Tol 3), as well as a qualitative analysis of spectra from two galactic H II regions (NGC 3603 & NGC 3576). It serves a two-fold purpose: first, to understand the CCD reduction, spectra extraction and different nebular analysis methods, together with their applications and limitations, preparatory to studies using the Southern African Large Telescope (SALT) and second, to extend current star formation related research to include extragalactic starburst galaxies. The observations were carried out using the 1.9m telescope (equipped with a grating spectroscope and CCD detector) of the South African Astronomical Observatory (SAAO), during the period 1 to 7 March 2005. The necessary CCD data reduction, spectra extraction, wavelength and flux calibration, Doppler shift as well as reddening correction procedures were performed before the emission lines were identified and measured. A full nebular analysis, including temperature, density, metallicity (oxygen abundance) and other chemical abundance determinations, was performed on the blue compact galaxies (BCGs). Two different nebular analysis packages viz. IRAF's nebular and SNAP were used, with all the results well within the range of values expected for metal poor BCGs. Recommendations on the different methods and their applications are made.

  4. Relativistic Effects on Reflection X-ray Spectra of AGN

    SciTech Connect

    Lee, Khee-Gan; Fuerst, Steven V.; Brandwardi-Raymond, Graziella; Wu, Kinwah; Crowley, Oliver; /University Coll. London

    2007-01-05

    We have calculated the reflection component of the X-ray spectra of active galactic nuclei (AGN) and shown that they can be significantly modified by the relativistic motion of the accretion flow and various gravitational effects of the central black hole. The absorption edges in the reflection spectra suffer severe energy shifts and smearing. The degree of distortion depends on the system parameters, and the dependence is stronger for some parameters such as the inner radius of the accretion disk and the disk viewing inclination angles. The relativistic effects are significant and are observable. Improper treatment of the reflection component of the X-ray continuum in spectral fittings will give rise to spurious line-like features, which will mimic the fluorescent emission lines and mask the relativistic signatures of the lines.

  5. Line emission tomography for CDX-U using filtered diodes

    SciTech Connect

    Stutman, D.; Menard, J.; Hwang, Y.S.; Choe, W.; Ono, M.; Finkenthal, M.; Soukhanovskii, V.; May, M.J.; Regan, S.P.; Moos, H.W.

    1997-01-01

    Electron density and temperature in the CDX-U low aspect ratio tokamak are too low to allow observation of fast magnetohydrodynamic activity using soft x-ray continuum emission. However, spectroscopic measurements show that extreme ultraviolet (XUV) line emission of intrinsic impurities is bright enough to observe such activity. In addition, a fast monitoring system for local temperature changes in the plasma core is required for planned auxiliary heating experiments. We present a spectrally resolved tomographic system for fast imaging of OVI 2s{endash}np, 2p{endash}nd (n{ge}3), CV 1s{sup 2}{endash}1s2p and CVI 1s{endash}2p XUV transitions. Using this emission, we can study both core and edge MHD activity, while the CVI to CV intensity ratio can indicate local changes in electron temperature. To achieve maximal throughput together with the needed spectral resolution, we use arrays of surface barrier diodes filtered with bandpass elemental filters. Using M edge filters (Zr, Pd, and Ag), we achieve both good discrimination between the above charge states and large transmission at the wavelengths of interest. Preliminary results obtained from CDX-U are presented. {copyright} {ital 1997 American Institute of Physics.}

  6. Asymmetries in coronal spectral lines and emission measure distribution

    SciTech Connect

    Tripathi, Durgesh; Klimchuk, James A.

    2013-12-10

    It has previously been argued that (1) spicules do not provide enough pre-heated plasma to fill the corona, and (2) even if they did, additional heating would be required to keep the plasma hot as it expands upward. Here we address whether spicules play an important role by injecting plasma at cooler temperatures (<2 MK), which then gets heated to coronal values at higher altitudes. We measure red-blue asymmetries in line profiles formed over a wide range of temperatures in the bright moss areas of two active regions. We derive emission measure distributions from the excess wing emission. We find that the asymmetries and emission measures are small and conclude that spicules do not inject an important (dominant) mass flux into the cores of active regions at temperatures >0.6 MK (log T > 5.8). These conclusions apply not only to spicules but also to any process that suddenly heats and accelerates chromospheric plasma (e.g., a chromospheric nanoflare). The traditional picture of coronal heating and chromospheric evaporation appears to remain the most likely explanation of the active region corona.

  7. Outflow and hot dust emission in broad absorption line quasars

    SciTech Connect

    Zhang, Shaohua; Zhou, Hongyan; Wang, Huiyuan; Wang, Tinggui; Xing, Feijun; Jiang, Peng; Zhang, Kai E-mail: whywang@mail.ustc.edu.cn

    2014-05-01

    We have investigated a sample of 2099 broad absorption line (BAL) quasars with z = 1.7-2.2 built from the Sloan Digital Sky Survey Data Release Seven and the Wide-field Infrared Survey. This sample is collected from two BAL quasar samples in the literature and is refined by our new algorithm. Correlations of outflow velocity and strength with a hot dust indicator (β{sub NIR}) and other quasar physical parameters—such as an Eddington ratio, luminosity, and a UV continuum slope—are explored in order to figure out which parameters drive outflows. Here β{sub NIR} is the near-infrared continuum slope, which is a good indicator of the amount of hot dust emission relative to the accretion disk emission. We confirm previous findings that outflow properties moderately or weakly depend on the Eddington ratio, UV slope, and luminosity. For the first time, we report moderate and significant correlations of outflow strength and velocity with β{sub NIR} in BAL quasars. It is consistent with the behavior of blueshifted broad emission lines in non-BAL quasars. The statistical analysis and composite spectra study both reveal that outflow strength and velocity are more strongly correlated with β{sub NIR} than the Eddington ratio, luminosity, and UV slope. In particular, the composites show that the entire C IV absorption profile shifts blueward and broadens as β{sub NIR} increases, while the Eddington ratio and UV slope only affect the high and low velocity part of outflows, respectively. We discuss several potential processes and suggest that the dusty outflow scenario, i.e., that dust is intrinsic to outflows and may contribute to the outflow acceleration, is most likely.

  8. AGN Physics in the CTA Era

    NASA Astrophysics Data System (ADS)

    Zech, Andreas; Boisson, Catherine; Sol, Hélène

    With the start of its Preparatory Phase, a new step has been made towards the construction of CTA, the future large Cherenkov Telescope Array of ground-based gamma-ray astronomy. A two-day workshop devoted to "AGN physics in the CTA era" will be held in Toulouse, May 16th-17th 2011, in parallel to a general meeting of the CTA consortium. Combining reviews and contributed talks, the meeting will aim to present the current state of the art and to characterize future observing programmes for the various facets of AGN science at very high energies (VHE). Topics to be discussed include AGN population studies, particle acceleration and VHE emission models, variability studies, multiwavelength approach, EBL connection, VHE extended emission (radiogalaxies, pair haloes, diffuse background), passive black holes, primordial black holes ... Further information, including the full program, can be found on the conference webpage: http://cta.obspm.fr/agnworkshop2011/

  9. 40 CFR 1060.515 - How do I test EPA Nonroad Fuel Lines and EPA Cold-Weather Fuel Lines for permeation emissions?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... and EPA Cold-Weather Fuel Lines for permeation emissions? 1060.515 Section 1060.515 Protection of... Nonroad Fuel Lines and EPA Cold-Weather Fuel Lines for permeation emissions? Measure emission as follows for EPA Nonroad Fuel Lines and EPA Cold-Weather Fuel Lines: (a) Prior to permeation testing, use...

  10. 40 CFR 1060.515 - How do I test EPA Nonroad Fuel Lines and EPA Cold-Weather Fuel Lines for permeation emissions?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... and EPA Cold-Weather Fuel Lines for permeation emissions? 1060.515 Section 1060.515 Protection of... Nonroad Fuel Lines and EPA Cold-Weather Fuel Lines for permeation emissions? Measure emission as follows for EPA Nonroad Fuel Lines and EPA Cold-Weather Fuel Lines: (a) Prior to permeation testing, use...

  11. 40 CFR 1060.515 - How do I test EPA Nonroad Fuel Lines and EPA Cold-Weather Fuel Lines for permeation emissions?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... and EPA Cold-Weather Fuel Lines for permeation emissions? 1060.515 Section 1060.515 Protection of... Nonroad Fuel Lines and EPA Cold-Weather Fuel Lines for permeation emissions? Measure emission as follows for EPA Nonroad Fuel Lines and EPA Cold-Weather Fuel Lines: (a) Prior to permeation testing, use...

  12. 40 CFR 1060.515 - How do I test EPA Nonroad Fuel Lines and EPA Cold-Weather Fuel Lines for permeation emissions?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... and EPA Cold-Weather Fuel Lines for permeation emissions? 1060.515 Section 1060.515 Protection of... Nonroad Fuel Lines and EPA Cold-Weather Fuel Lines for permeation emissions? Measure emission as follows for EPA Nonroad Fuel Lines and EPA Cold-Weather Fuel Lines: (a) Prior to permeation testing, use...

  13. 40 CFR 1060.515 - How do I test EPA Nonroad Fuel Lines and EPA Cold-Weather Fuel Lines for permeation emissions?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... and EPA Cold-Weather Fuel Lines for permeation emissions? 1060.515 Section 1060.515 Protection of... Nonroad Fuel Lines and EPA Cold-Weather Fuel Lines for permeation emissions? Measure emission as follows for EPA Nonroad Fuel Lines and EPA Cold-Weather Fuel Lines: (a) Prior to permeation testing, use...

  14. Multi-wavelength properties and SMBH's masses of the isolated AGNs in the Local Universe

    NASA Astrophysics Data System (ADS)

    Vavilova, I. B.; Vasylenko, A. A.; Babyk, Iu. V.; Pulatova, N. G.

    2016-08-01

    The sample of 36 nearest isolated AGNs was cross-matched by 2MIG and Veron-Cetty catalogues and limited to Ks ≤ 12.0m and Vr < 15 000 km/s in the northern sky (δ ≥ -15°). These objects were in isolation during ~ 3 Gyrs. For revealing their multi-wavelength properties we used all the available databases obtained with ground-based and space observatories (from radio to X-ray ranges). It is allowed us to separate the internal evolution mechanisms from the environment influence and consider them as two separate processes related to fueling nuclear activity and accretion on the SMBHs outside of the environment. In this report we present briefly main results, which were already published (Pulatova N., Vavilova I., Sawangwit U. et al. The 2MIG isolated AGNs - I. General and multiwavelength properties of AGNs and host galaxies in the northern sky, MNRAS, 447, Issue 3, p. 2209-2223 (2015)). We accentuate that for the first time we revealed that the host isolated galaxies with AGNs of Sy1 type (without faint companions) appear to possess the bar morphological features (e.g., the interaction with neighboring galaxies is not necessary condition for broad-line region formation). We give also current results as concerns with more detail X-ray analysis, emission features and spectral models for several AGNs for which a cumulative soft and hard energy spectrum was reconstructed. The estimates of SMBH masses show that are systematically lower than the SMBH masses of AGNs located in a dense environment.

  15. Infrared and X-Ray Evidence of an AGN in the NGC 3256 Southern Nucleus

    NASA Astrophysics Data System (ADS)

    Ohyama, Youichi; Terashima, Yuichi; Sakamoto, Kazushi

    2015-06-01

    We investigate signs of an active galactic nucleus (AGN) in the luminous infrared (IR) galaxy NGC 3256 at both IR and X-ray wavelengths. NGC 3256 has double nuclei: the northern and southern (hereafter, N and S nuclei, respectively). We show that the Spitzer IRAC colors extracted at the S nucleus are AGN-like, and the Spitzer IRS spectrum is bluer at \\lt 6 μm than at the N nucleus. We built for the S nucleus an AGN-starburst composite model with a heavily absorbed AGN to successfully reproduce not only the IRAC and IRS specrophotometries at ≃ 3″, but also the very deep silicate 9.7 μm absorption observed at a 0.″ 36 scale by Díaz-Santos et al. We found a 2.2 μm compact source at the S nucleus in an HST NICMOS image and identified its unresolved core (at 0.″ 26 resolution) with the compact core in previous mid-infrared observations at comparable resolution. The flux of the 2.2 μm core is consistent with our AGN spectral energy distribution model. We also analyzed a deeper than ever Chandra X-ray spectrum of the unresolved (at 0.″ 5 resolution) source at the S nucleus. We found that a dual-component power-law model (for primary and scattered ones) fits an apparently very hard spectrum with a moderately large absorption on the primary component. Together with a limit on equivalent width of a fluorescent Fe-K emission line at 6.4 keV, the X-ray spectrum is consistent with a typical Compton-thin Seyfert 2. We therefore suggest that the S nucleus hosts a heavily absorbed low-luminosity AGN.

  16. 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.

  17. About the emission line sequence of H II galaxies

    NASA Astrophysics Data System (ADS)

    Stasińska, G.; Izotov, Y.

    2003-09-01

    We consider 400 H II galaxies in which the oxygen abundances were obtained by electron temperature based methods. We split the sample in three metallicity bins. In each bin, a narrow sequence is found not only in pure emission line ratio diagrams but also in terms of H beta equivalent width, indicating the existence of an evolutionary sequence. Our diagrams show unambiguously the existence of an evolution on a timescale of a few Myr. We compare the observed sequences with photoionization models of appropriate metallicity. In order to understand the evolution of H II galaxies one needs to consider the evolution of the gas as well as that of the stars. The observations require EW(H beta ) to decrease more rapidly than predicted by the passive evolution of a starburst. A photoionized adiabatic expanding bubble with a covering factor decreasing with time reproduces most diagrams. However, the question of the heating of H II galaxies and the origin of the nebular He II lambda 4686 emission are not settled. We find evidence for self-enrichment in nitrogen on a time scale of several Myr.

  18. Spectral classification of emission-line galaxies from the Sloan Digital Sky Survey. I. An improved classification for high-redshift galaxies

    NASA Astrophysics Data System (ADS)

    Lamareille, F.

    2010-01-01

    Aims: We study the spectral classification of emission-line galaxies as starforming galaxies or active galactic nuclei (AGNs). With the high-quality data from the Sloan Digital Sky Survey (SDSS) we define an improved classification to be used for high-redshift galaxies. Methods: We classify emission-line galaxies of the SDSS according to the latest standard recipe using [Oiii]λ5007, [Nii]λ6584, [Sii]λ6717+6731, Hα, and Hβ emission lines. We obtain four classes: starforming galaxies, Seyfert 2, LINERs, and composites. We then examine where these galaxies fall in the blue diagram used at high redshift (i.e. log([Oiii]λ5007/Hβ) vs. log([Oii]λλ3726+3729/Hβ). Results: We define new improved boundaries in the blue diagram for starforming galaxies, Seyfert 2, LINERs, SF/Sy2, and SF-LIN/comp classes. We maximize the success rate to 99.7% for the detection of starforming galaxies to 86% for the Seyfert 2 (including the SF/Sy2 region) and to 91% for the LINERs. We also minimize the contamination to 16% in the region of starforming galaxies. We cannot reliably separate composites from starforming galaxies and LINERs, but we define an SF-LIN/comp region where most of them fall (64%).

  19. Constraining the Dynamical Importance of Hot Gas and Radiation Pressure in Quasar Outflows Using Emission Line Ratios

    NASA Astrophysics Data System (ADS)

    Stern, Jonathan; Faucher-Giguère, Claude-André; Zakamska, Nadia L.; Hennawi, Joseph F.

    2016-03-01

    Quasar feedback models often predict an expanding hot gas bubble that drives a galaxy-scale outflow. In many circumstances this hot gas radiates inefficiently and is therefore difficult to observe directly. We present an indirect method to detect the presence of a hot bubble using hydrostatic photoionization calculations of the cold (∼ {10}4 {{K}}) line-emitting gas. We compare our calculations with observations of the broad line region, the inner face of the torus, the narrow line region (NLR), and the extended NLR, and thus constrain the hot gas pressure at distances 0.1 {{pc}}{--}10 {{kpc}} from the center. We find that emission line ratios observed in the average quasar spectrum are consistent with radiation-pressure-dominated models on all scales. On scales \\lt 40 {{pc}} a dynamically significant hot gas pressure is ruled out, while on larger scales the hot gas pressure cannot exceed six times the local radiation pressure. In individual quasars, ≈25% of quasars exhibit NLR ratios that are inconsistent with radiation-pressure-dominated models, although in these objects the hot gas pressure is also unlikely to exceed the radiation pressure by an order of magnitude or more. The derived upper limits on the hot gas pressure imply that the instantaneous gas pressure force acting on galaxy-scale outflows falls short of the time-averaged force needed to explain the large momentum fluxes \\dot{p}\\gg {L}{{AGN}}/c inferred for galaxy-scale outflows. This apparent discrepancy can be reconciled if optical quasars previously experienced a buried, fully obscured phase during which the hot gas bubble was more effectively confined and during which galactic wind acceleration occurred.

  20. 40 CFR 63.1569 - What are my requirements for HAP emissions from bypass lines?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... emissions from bypass lines? 63.1569 Section 63.1569 Protection of Environment ENVIRONMENTAL PROTECTION..., Catalytic Reforming Units, Sulfur Recovery Units, and Bypass Lines § 63.1569 What are my requirements for HAP emissions from bypass lines? (a) What work practice standards must I meet? (1) You must meet...

  1. The Intermediate-line Region in Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Adhikari, T. P.; Różańska, A.; Czerny, B.; Hryniewicz, K.; Ferland, G. J.

    2016-11-01

    We show that the recently observed suppression of the gap between the broad-line region (BLR) and the narrow-line region (NLR) in some active galactic nuclei (AGNs) can be fully explained by an increase of the gas density in the emitting region. Our model predicts the formation of the intermediate-line region (ILR) that is observed in some Seyfert galaxies by the detection of emission lines with intermediate-velocity FWHM ∼ 700–1200 km s‑1. These lines are believed to be originating from an ILR located somewhere between the BLR and NLR. As was previously proved, the apparent gap is assumed to be caused by the presence of dust beyond the sublimation radius. Our computations with the use of the cloudy photoionization code show that the differences in the shape of the spectral energy distribution from the central region of AGNs do not diminish the apparent gap in the line emission in those objects. A strong discontinuity in the line emission versus radius exists for all lines at the dust sublimation radius. However, increasing the gas density to ∼{10}11.5 cm‑3 at the sublimation radius provides the continuous line emission versus radius and fully explains the recently observed lack of apparent gap in some AGNs. We show that such a high density is consistent with the density of upper layers of an accretion disk atmosphere. Therefore, the upper layers of the disk atmosphere can give rise to the formation of observed emission-line clouds.

  2. The HST quasar absorption line key project. 9: An emission-line study of PG 2251+113

    NASA Technical Reports Server (NTRS)

    Espey, Brian R.; Turnshek, David A.; Lee, Lincoln; Bergeron, Jacqueline; Boksenberg, Alec; Hartig, George F.; Jannuzi, Buell T.; Sargent, W. L. W.; Savage, Blair D.; Schneider, Donald P.

    1994-01-01

    We present Hubble Space Telescope (HST) and quasi-simultaneous ground-based observations of the z = 0.3252 QSO PG 2251+113. We find a correlation between line widths and the critical density for de-excitation of the forbidden emission lines observed in this object. We can show that this correlation also applies to the semiforbidden and possibly also the permitted lines which arise in the broad emission-line region. While this result was predicted from statistical studies, it has never previously been shown to hold in detail in any individual object. This relationship between the narrow and broad emission-line regions may help constrain dynamical models of both regions. We examine the implications of this result for a simple radial infall model of the emitting gas developed to explain the origin of narrow-line profiles.

  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. A catalog of early-type emission-line stars and Hα line profiles from LAMOST DR2

    NASA Astrophysics Data System (ADS)

    Hou, Wen; Luo, A.-Li; Hu, Jing-Yao; Yang, Hai-Feng; Du, Chang-De; Liu, Chao; Lee, Chien-De; Lin, Chien-Cheng; Wang, Yue-Fei; Zhang, Yong; Cao, Zi-Huang; Hou, Yong-Hui

    2016-09-01

    We present a catalog including 11 204 spectra of 10 436 early-type emission-line stars from LAMOST DR2, among which 9752 early-type emission-line spectra are newly discovered. For these early-type emission-line stars, we discuss the morphological and physical properties of their low-resolution spectra. In this spectral sample, the Hα emission profiles display a wide variety of shapes. Based on the Hα line profiles, these spectra are categorized into five distinct classes: single-peak emission, single-peak emission in absorption, double-peak emission, double-peak emission in absorption, and P-Cygni profiles. To better understand what causes the Hα line profiles, we divide these objects into four types from the perspective of physical classification, which include classical Be stars, Herbig Ae/Be stars, close binaries and spectra contaminated by HΠ regions. The majority of Herbig Ae/Be stars and classical Be stars are identified and separated using a (H-K, K-W1) color-color diagram. We also discuss 31 binary systems that are listed in the SIMBAD on-line catalog and identify 3600 spectra contaminated by HΠ regions after cross-matching with positions in the Dubout-Crillon catalog. A statistical analysis of line profiles versus classifications is then conducted in order to understand the distribution of Hα profiles for each type in our sample. Finally, we also provide a table of 172 spectra with Fe Π emission lines and roughly calculate stellar wind velocities for seven spectra with P-Cygni profiles.

  5. Simulations of the OzDES AGN reverberation mapping project

    DOE PAGES

    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

  6. Herschel-PACS Observations of Far-IR CO Line Emission in NGC 1068: Highly Excited Molecular Gas in the Circumnuclear Disk

    NASA Astrophysics Data System (ADS)

    Hailey-Dunsheath, S.; Sturm, E.; Fischer, J.; Sternberg, A.; Graciá-Carpio, J.; Davies, R.; González-Alfonso, E.; Mark, D.; Poglitsch, A.; Contursi, A.; Genzel, R.; Lutz, D.; Tacconi, L.; Veilleux, S.; Verma, A.; de Jong, J. A.

    2012-08-01

    We report the detection of far-IR CO rotational emission from the prototypical Seyfert 2 galaxy NGC 1068. Using Herschel-PACS, we have detected 11 transitions in the J upper = 14-30 (E upper/kB = 580-2565 K) range, all of which are consistent with arising from within the central 10'' (700 pc). The detected transitions are modeled as arising from two different components: a moderate-excitation (ME) component close to the galaxy systemic velocity and a high-excitation (HE) component that is blueshifted by ~80 km s-1. We employ a large velocity gradient model and derive n H2 ~ 105.6 cm-3, T kin ~ 170 K, and M H2 ~ 106.7 M ⊙ for the ME component and n H2 ~ 106.4 cm-3, T kin ~ 570 K, and M H2 ~ 105.6 M ⊙ for the HE component, although for both components the uncertainties in the density and mass are ±(0.6-0.9) dex. Both components arise from denser and possibly warmer gas than traced by low-J CO transitions, and the ME component likely makes a significant contribution to the mass budget in the nuclear region. We compare the CO line profiles with those of other molecular tracers observed at higher spatial and spectral resolution and find that the ME transitions are consistent with these lines arising in the ~200 pc diameter ring of material traced by H2 1-0 S(1) observations. The blueshift of the HE lines may also be consistent with the bluest regions of this H2 ring, but a better kinematic match is found with a clump of infalling gas ~40 pc north of the active galactic nucleus (AGN). We consider potential heating mechanisms and conclude that X-ray- or shock heating of both components is viable, while far-UV heating is unlikely. We discuss the prospects of placing the HE component near the AGN and conclude that while the moderate thermal pressure precludes an association with the ~1 pc radius H2O maser disk, the HE component could potentially be located only a few parsecs more distant from the AGN and might then provide the N H ~ 1025 cm-2 column obscuring the

  7. The BLR structure and dust torus size of AGN - Implications from photometric and dust reverberation mapping campaigns.

    NASA Astrophysics Data System (ADS)

    Pozo Nuñez, F.; Ramolla, M.; Westhues, C.; Haas, M.; Chini, R.; Steenbrugge, K.; Lemke, R.; Murphy, M.

    2014-03-01

    Photometric reverberation mapping (PRM) is a novel method used to study the geometry of the broad emission-line region (BLR), black hole masses and host-subtracted luminosities of active galactic nuclei (AGN). We obtained high-quality sampling data with small (15 to 80 cm) robotic telescopes at the observatory of the Ruhr-University Bochum, located in the Atacama desert in Chile.

  8. 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.

  9. 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.

  10. Star formation and AGN activity in the most luminous LINERs in the local universe

    NASA Astrophysics Data System (ADS)

    Pović, Mirjana; Márquez, Isabel; Netzer, Hagai; Masegosa, Josefa; Nordon, Raanan; Pérez, Enrique; Schoenell, William

    2016-11-01

    This work presents the properties of 42 objects in the group of the most luminous, highest star formation rate (SFR) low-ionization nuclear emission-line regions (LINERs) at z = 0.04-0.11. We obtained long-slit spectroscopy of the nuclear regions for all sources, and FIR data (Herschel and IRAS) for 13 of them. We measured emission-line intensities, extinction, stellar populations, stellar masses, ages, active galactic nuclei (AGN) luminosities, and SFRs. We find considerable differences from other low-redshift LINERs, in terms of extinction, and general similarity to star-forming galaxies. We confirm the existence of such luminous LINERs in the local universe, after being previously detected at z ˜ 0.3 by Tommasin et al. The median stellar mass of these LINERs corresponds to 6-7 × 1010 M⊙ which was found in previous work to correspond to the peak of relative growth rate of stellar populations and therefore for the highest SFRs. Other LINERs although showing similar AGN luminosities have lower SFR. We find that most of these sources have LAGN ˜ LSF suggesting co-evolution of black hole and stellar mass. In general, the fraction of local LINERs on the main sequence of star-forming galaxies is related to their AGN luminosity.

  11. Long-Term Variability of AGN at Hard X-Rays

    NASA Technical Reports Server (NTRS)

    Soldi, S.; Beckmann, V.; Baumgartner W. H.; Ponti, G.; Shrader, C. R.; Lubinski, P.; Krimm, H. A.; Mattana, F.; Tueller, J.

    2013-01-01

    Variability at all observed wavelengths is a distinctive property of active galactic nuclei (AGN). Hard X-rays provide us with a view of the innermost regions of AGN, mostly unbiased by absorption along the line of sight. Characterizing the intrinsic hard X-ray variability of a large AGN sample and comparing it to the results obtained at lower X-ray energies can significantly contribute to our understanding of the mechanisms underlying the high-energy radiation. Methods. Swift/BAT provides us with the unique opportunity to follow, on time scales of days to years and with a regular sampling, the 14-195 keV emission of the largest AGN sample available up to date for this kind of investigation. As a continuation of an early work on the first 9 months of BAT data, we study the amplitude of the variations, and their dependence on sub-class and on energy, for a sample of 110 radio quiet and radio loud AGN selected from the BAT 58-month survey. About 80 of the AGN in the sample are found to exhibit significant variability on months to years time scales, radio loud sources being the most variable. The amplitude of the variations and their energy dependence are incompatible with variability being driven at hard X-rays by changes of the absorption column density. In general, the variations in the 14-24 and 35-100 keV bands are well correlated, suggesting a common origin of the variability across the BAT energy band. However, radio quiet AGN display on average 10 larger variations at 14-24 keV than at 35-100 keV and a softer-when-brighter behavior for most of the Seyfert galaxies with detectable spectral variability on month time scale. In addition, sources with harder spectra are found to be more variable than softer ones. These properties are generally consistent with a variable power law continuum, in flux and shape, pivoting at energies 50 keV, to which a constant reflection component is superposed. When the same time scales are considered, the timing properties of AGN at

  12. 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.

  13. Warm ionized gas in CALIFA early-type galaxies. 2D emission-line patterns and kinematics for 32 galaxies

    NASA Astrophysics Data System (ADS)

    Gomes, J. M.; Papaderos, P.; Kehrig, C.; Vílchez, J. M.; Lehnert, M. D.; Sánchez, S. F.; Ziegler, B.; Breda, I.; Dos Reis, S. N.; Iglesias-Páramo, J.; Bland-Hawthorn, J.; Galbany, L.; Bomans, D. J.; Rosales-Ortega, F. F.; Cid Fernandes, R.; Walcher, C. J.; Falcón-Barroso, J.; García-Benito, R.; Márquez, I.; Del Olmo, A.; Masegosa, J.; Mollá, M.; Marino, R. A.; González Delgado, R. M.; López-Sánchez, Á. R.; Califa Collaboration

    2016-04-01

    Context. The morphological, spectroscopic, and kinematical properties of the warm interstellar medium (wim) in early-type galaxies (ETGs) hold key observational constraints to nuclear activity and the buildup history of these massive, quiescent systems. High-quality integral field spectroscopy (IFS) data with a wide spectral and spatial coverage, such as those from the CALIFA survey, offer an unprecedented opportunity for advancing our understanding of the wim in ETGs. Aims: This article centers on a 2D investigation of the wim component in 32 nearby (≲150 Mpc) ETGs from CALIFA, complementing a previous 1D analysis of the same sample. Methods: The analysis presented here includes Hα intensity and equivalent width (EW) maps and radial profiles, diagnostic emission-line ratios, and ionized-gas and stellar kinematics. It is supplemented by τ-ratio maps, which are a more efficient means to quantify the role of photoionization by the post-AGB stellar component than alternative mechanisms (e.g., AGN, low-level star formation). Results: Confirming and strengthening our previous conclusions, we find that ETGs span a broad continuous sequence in the properties of their wim, exemplified by two characteristic classes. The first (type i) comprises systems with a nearly constant EW(Hα) in their extranuclear component, which quantitatively agrees with (but is no proof of) the hypothesis that photoionization by the post-AGB stellar component is the main driver of extended wim emission. The second class (type ii) stands for virtually wim-evacuated ETGs with a very low (≤0.5 Å), outwardly increasing EW(Hα). These two classes appear indistinguishable from one another by their LINER-specific emission-line ratios in their extranuclear component. Here we extend the tentative classification we proposed previously by the type i+, which is assigned to a subset of type i ETGs exhibiting ongoing low-level star-forming activity in their periphery. This finding along with faint

  14. Tracing black hole accretion with SED decomposition and IR lines: from local galaxies to the high-z Universe

    NASA Astrophysics Data System (ADS)

    Gruppioni, C.; Berta, S.; Spinoglio, L.; Pereira-Santaella, M.; Pozzi, F.; Andreani, P.; Bonato, M.; De Zotti, G.; Malkan, M.; Negrello, M.; Vallini, L.; Vignali, C.

    2016-06-01

    We present new estimates of AGN accretion and star formation (SF) luminosity in galaxies obtained for the local 12 μm sample of Seyfert galaxies (12MGS), by performing a detailed broad-band spectral energy distribution (SED) decomposition including the emission of stars, dust heated by SF and a possible AGN dusty torus. Thanks to the availability of data from the X-rays to the sub-millimetre, we constrain and test the contribution of the stellar, AGN and SF components to the SEDs. The availability of Spitzer-InfraRed Spectrograph (IRS) low-resolution mid-infrared (mid-IR) spectra is crucial to constrain the dusty torus component at its peak wavelengths. The results of SED fitting are also tested against the available information in other bands: the reconstructed AGN bolometric luminosity is compared to those derived from X-rays and from the high excitation IR lines tracing AGN activity like [Ne V] and [O IV]. The IR luminosity due to SF and the intrinsic AGN bolometric luminosity are shown to be strongly related to the IR line luminosity. Variations of these relations with different AGN fractions are investigated, showing that the relation dispersions are mainly due to different AGN relative contribution within the galaxy. Extrapolating these local relations between line and SF or AGN luminosities to higher redshifts, by means of recent Herschel galaxy evolution results, we then obtain mid- and far-IR line luminosity functions useful to estimate how many star-forming galaxies and AGN we expect to detect in the different lines at different redshifts and luminosities with future IR facilities (e.g. JWST, SPICA).

  15. On the sodium D line emission in the terrestrial nightglow

    NASA Astrophysics Data System (ADS)

    Plane, John; Oetjen, Hilke; de Miranda, Marcelo; Saiz-Lopez, Alfonso; Gausa, Michael; Williams, Bifford

    2012-01-01

    Emission from atomic Na, consisting of a doublet of lines at 589.0 and 589.6 nm, is a prominent feature of the earth’s nightglow. A large data-base of measurements of the relative intensities of the D lines (RD) was gathered at three locations: the ALOMAR observatory, Andenes (Norway, 69°N), Kuujjuarapik (Canada, 55°N) and the Danum Valley (Borneo, 8°N). RD varies between 1.5 and 2.0, with an average value of 1.67. These results were interpreted using a theoretical model of the Na nightglow which involves initial production of electronically excited NaO(A2Σ) from the reaction between Na and O3, followed either by reaction with O to generate Na(2PJ) with a branching ratio of 1/6 and a J=3/2 to 1/2 propensity of 2.0, or quenching of NaO(A) to NaO(X2Π) by O2. The resulting NaO(X) then reacts with O to generate Na(2PJ) with a branching ratio of 1/6 and a J=3/2 to 1/2 propensity of 1.5. These branching ratios and spin-orbit propensities are derived from statistical correlation of the electronic potential energy surfaces connecting the reactants NaO(A)+O and NaO(X)+O with the products Na+O2, through the Na+O2- ion-pair intermediate. A fit of this statistical model to the results of an earlier laboratory study (Slanger et al., 2005), where RD was measured as a function of the ratio [O]/[O2], indicates that the rate coefficient for the quenching of NaO(A) by O2 is around 1×10-11 cm3 molecule-1 s-1. The statistical model is also in good accord with recent high resolution observations of the Na D line widths (Harrell et al., 2010). An atmospheric model is then used to show that gravity wave-driven perturbations to the Na layer can account for the observed variability of RD.

  16. 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°.

  17. Recent Results for AGN Observed by the Rossi X-Ray Timing Explorer

    NASA Technical Reports Server (NTRS)

    Madejski, G. M.; Done, C.; Zycki, P.

    2000-01-01

    The Rossi X-ray Timing Explorer (RXTE) has produced many excellent observations of active galaxies, providing the best sensitivity in the 10 - 20 keV range so far. This presentation reports selected RTXE data for AGN in the context of the currently popular models. One is the recent result for two Seyfert 1 galaxies, NGC 5548 and IC4329a: both show the "canonical" Seyfert I X-ray spectra, with an underlying power law, plus Gaussian iron K line and Compton reflection. Interestingly, in both cases, the profile of the Fe K line does not extend as far to the red as seen in the famous NCG-6-30-15, and this indicates that the regions where the Fe K lines originate in AGN are diverse. Independently, in both objects we see a strong spectral variability of the primary continua, which soften as the sources brighten. The second result is for the heavily absorbed Seyfert 2 NGC 4945. The RXTE data confirm the strong absorption corresponding to the optical depth to electron scattering of about 2, but also reveal rapid variability of the hard (8-30 keV) X-ray emission on a time scale of a day or less. This suggests that for NGC 4945, the putative parsec-size molecular torus cannot be both geometrically and optically thick, and implies that the Cosmic X-ray Background is unlikely to be made up primarily of AGN with geometry as inferred for this object.

  18. Alma observations of nearby luminous infrared galaxies with various agn energetic contributions using dense gas tracers

    SciTech Connect

    Imanishi, Masatoshi; Nakanishi, Kouichiro

    2014-07-01

    We present the results of our ALMA Cycle 0 observations, using HCN/HCO{sup +}/HNC J = 4-3 lines, of six nearby luminous infrared galaxies with various energetic contributions from active galactic nuclei (AGNs) estimated from previous infrared spectroscopy. These lines are very effective for probing the physical properties of high-density molecular gas around the hidden energy sources in the nuclear regions of these galaxies. We find that HCN to HCO{sup +} J = 4-3 flux ratios tend to be higher in AGN-important galaxies than in starburst-dominated regions, as was seen at the J = 1-0 transition, while there is no clear difference in the HCN-to-HNC J = 4-3 flux ratios among observed sources. A galaxy with a starburst-type infrared spectral shape and very large molecular line widths shows a high HCN-to-HCO{sup +} J = 4-3 flux ratio, which could be due to turbulence-induced heating. We propose that enhanced HCN J = 4-3 emission relative to HCO{sup +} J = 4-3 could be used to detect more energetic activity than normal starbursts, including deeply buried AGNs, in dusty galaxy populations.

  19. A photometric catalogue of southern emission-line stars

    NASA Astrophysics Data System (ADS)

    de Winter, D.; van den Ancker, M. E.; Maira, A.; Thé, P. S.; Djie, H. R. E. Tjin A.; Redondo, I.; Eiroa, C.; Molster, F. J.

    2001-12-01

    We present a catalogue of previously unpublished optical and infrared photometry for a sample of 162 emission-line objects and shell stars visible from the southern hemisphere. The data were obtained between 1978 and 1997 in the Walraven (WULBV), Johnson/Cousins (UBV(RI)c) and ESO and SAAO near-infrared (JHKLM) photometric systems. Most of the observed objects are Herbig Ae/Be (HAeBe) stars or HAeBe candidates appearing in the list of HAeBe candidates of Thé et al. (1994), although several B[e] stars, LBVs and T Tauri stars are also included in our sample. For many of the stars the data presented here are the first photo-electric measurements in the literature. The resulting catalogue consists of 1809 photometric measurements. Optical variability was detected in 66 out of the 116 sources that were observed more than once. 15 out of the 50 stars observed multiple times in the infrared showed variability at 2.2 mu m (K band). Based on observations collected at the European Southern Observatory, La Silla, Chile and on observations collected at the South African Astronomical Observatory. Tables 2-4 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http:/ /cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/380/609

  20. Coronal Physics and the Chandra Emission Line Project

    NASA Technical Reports Server (NTRS)

    Brickhouse, N. S.; Drake, J. J.

    2000-01-01

    With the launch of the Chandra X-ray Observatory, high resolution X-ray spectroscopy of cosmic sources has begun. Early, deep observations of three stellar coronal sources Capella, Procyon, and HR 1099 are providing not only invaluable calibration data, but also benchmarks for plasma spectral models. These models are needed to interpret data from stellar coronae, galaxies and clusters of galaxies, supernova, remnants and other astrophysical sources. They have been called into question in recent years as problems with understanding low resolution ASCA and moderate resolution Extreme Ultraviolet Explorer Satellite (EUVE) data have arisen. The Emission Line Project is a collaborative effort, to improve the models, with Phase I being the comparison of models with observed spectra of Capella, Procyon, and HR 1099. Goals of these comparisons are (1) to determine and verify accurate and robust diagnostics and (2) to identify and prioritize issues in fundamental spectroscopy which will require further theoretical and/or laboratory work. A critical issue in exploiting the coronal data for these purposes is to understand the extent, to which common simplifying assumptions (coronal equilibrium, negligible optical depth) apply. We will discuss recent, advances in our understanding of stellar coronae, in this context.

  1. Coronal Physics and the Chandra Emission Line Project

    NASA Technical Reports Server (NTRS)

    Brickhouse, Nancy

    1999-01-01

    With the launch of the Chandra X-ray Observatory, high resolution X-ray spectroscopy of cosmic sources has begun. Early, deep observations of three stellar coronal sources will provide not only invaluable calibration data, but will also give us benchmarks for plasma spectral modeling codes. These codes are to interpret data from stellar coronae, galaxies and clusters of galaxies. supernova remnants and other astrophysical sources, but they have been called into question in recent years as problems with understanding moderate resolution ASCA and EUVE data have arisen. The Emission Line Project is a collaborative effort to improve the models, with Phase 1 being the comparison of models with observed spectra of Capella, Procyon, and HR, 1099. Goals of these comparisons are (1) to determine and verify accurate and robust diagnostics and (2) to identify and prioritize issues in fundamental spectroscopy which will require further theoretical and/or laboratory work. A critical issue in exploiting the coronal data for these purposes is to understand the extent to which common simplifying assumptions (coronal equilibrium, time-independence, negligible optical depth) apply. We will discuss recent advances in our understanding of stellar coronae in this context.

  2. Wide-band X-ray spectral and timing analysis of AGNs

    NASA Astrophysics Data System (ADS)

    Hiragi, Kazuyoshi; Fukazawa, Yasushi; Mizuno, Motohiro; Takahashi, Hiromitsu; Yamasaki, Tomonori

    X-ray spectra of AGNs contain conplex features such as the continuum, emission line, ab-sorption, reflection component, high energy cut-off. These features are thought to reflect the material structure around AGN, and X-ray studies can clarify a physical geometry of AGNs. Especially, the hard X-ray observation above 10 keV is important to measure the reflection component. So far, hard X-ray studies of time variation of AGN spectra have been limited because of high background rate. Suzaku HXD achieve the highest S/N ratio by an effective background rejection. Combining the data with the XIS soft X-ray date, we can study the AGN X-ray spectra in more detail than ever. Here, we report the spectral and timing analysis of 14 Seyfert galaxies observed with Suzaku, in order to decompose each spectral component. The reflection component via a torus is considered to be less variable, while the varible component is considered to come from the central engine directly. Using this consideration, we tried to decompose a direct component and a reflection component. We compared the spectral parameters obtained by spectral fitting with direct nuclear plus reflection with those obtained from the difference spectra between high and low state. In particular, we forcus attention on the power-law index, reflection fraction, and the Fe-Ka line. As a result, the photon index, the Fe line intensity, and the refrection component is almost the same between high and low state. However, some of them are not the case, and the equivalent width of Fe-Ka line against the best-fit reflection component is unreasonable for some objects. These indicate that two-component model is valid for most of Seyfert galaxies, but the behavior of some Seyfert galaxies cannot be explained by two-conmponent model. Highly ionized Fe-K lines are observed as both emission and absorption, and some objects show a time variability of these lines. We will report this matter.

  3. On the 630 nm red-line pulsating aurora: Red-line Emission Geospace Observatory observations and model simulations

    NASA Astrophysics Data System (ADS)

    Liang, Jun; Donovan, E.; Jackel, B.; Spanswick, E.; Gillies, M.

    2016-08-01

    In this study, we present observations of red-line (630 nm) pulsating auroras using the camera system of Red-line Emission Geospace Observatory (REGO), during a geomagnetic storm interval. We also develop a time-dependent model to simulate the 630 nm auroral pulsations in response to modulated precipitation inputs and compare the model outputs with REGO observations. Key results are as follows. (1) Notwithstanding the long radiative timescale of the 630 nm emission, red-line auroras can still be modulated by pulsating electron precipitations and feature noticeable oscillations, which constitute the red-line pulsating auroral phenomena. (2) In a majority of cases, the oscillation magnitude of red-line pulsating auroras is substantially smaller than that of the concurrent pulsating auroras seen on Thermal Emission Imaging System whitelight images (generally dominated by 557.7 nm green-line emissions). Under certain circumstances, e.g., when the characteristic energy of the precipitation is very high, some of the pulsating auroras may not show discernible imprints on red line. (3) The altitude range contributing most to the red-line pulsating aurora is systematically lower than that of the steady-state red-line aurora, since the slower O(1D) loss rate at higher altitudes tends to suppress the oscillation range of the 630 nm emission rate. (4) We find that some pulsating auroral patches are characterized by enhanced red-to-green color ratio during their on time, hinting that the percentage increase of the red-line auroral component exceeds that of the green-line auroral component for those patches. We suggest that those special patches might possibly be associated with lower energy (<1 keV) electron precipitations.

  4. Radio AGN signatures in massive quiescent galaxies out to z=1.5

    NASA Astrophysics Data System (ADS)

    Järvelä, Emilia

    2016-08-01

    Detection of gamma-rays from narrow-line Seyfert 1 galaxies (NLS1) by Fermi confirmed the presence of powerful relativistic jets in them, and thus challenged our understanding of active galactic nuclei (AGN). In the current AGN paradigm powerful relativistic jets are produced in massive elliptical galaxies with supermassive black holes. NLS1s differ from them significantly; they harbour lower mass black holes accreting at higher Eddington ratios, have preferably compact radio morphology, reside mostly in spiral galaxies, and were thought to be radio-quiet.Fermi's discovery invokes questions about the AGN evolution; what triggers and maintains the AGN activity, and what are the evolutionary lines of the different populations? It is also necessary to revise the AGN unification schemes to fit in NLS1s. They convolute the whole AGN scenario, but offer us a new look on the jet phenomena and will help us construct a more comprehensive big picture of AGN.Despite their importance, NLS1s are rather poorly studied as a class. For example, some NLS1s seem to be totally radio-silent, but a considerable fraction are radio-loud and thus probably host jets. This, along with other observational evidence, implies that they do not form a homogeneous class. However, it remains unclear what is triggering the radio loudness in some of them, but, for example, the properties of the host galaxy and the large-scale environment might play a role. Also the parent population of NLS1s remains an open question.We used various statistical methods, for example, multiwavelength correlations and principal component analysis to study a large sample of NLS1 sources. We will present the results and discuss the interplay between their properties, such as emission properties, black hole masses, large-scale environments, and their effect on radio loudness. We will also introduce the Metsähovi Radio Observatory NLS1 galaxy observing programme, which is the first one dedicated to systematical observations

  5. Broadband, radio spectro-polarimetric observations of radiative-mode and jet-mode AGN

    NASA Astrophysics Data System (ADS)

    O'Sullivan, Shane P.; Purcell, C. R.; Farnes, J. S.; Sun, X. H.; Anderson, C. S.; Gaensler, B. M.

    2016-08-01

    Observations of polarised synchrotron emission from radio-loud AGN, along with the associated Faraday rotation, provides a highly sensitive probe of magneto-ionic material in AGN environments. Here we present the results from our investigation of the environments of two broad classes of radio-loud AGN (radiative-mode & jet mode) using broadband radio spectro-polarimetry, from 1 to 10 GHz. By spectrally resolving the spatial unresolved polarised emission, we directly probe the different magneto-ionic environments of radiative-mode and jet-mode AGN. We also present results for the dependence of the polarisation and Faraday rotation properties of the two AGN types based on the number of polarised emission components, the spectral index, and the intrinsic magnetic field structure. Finally, we outline the prospects for future Faraday rotation studies of radio-loud AGN with the Australian SKA Pathfinder telescope, and present some preliminary results from the early science observations.

  6. Spectropolarimetric test of the relativistic disk model for the broad emission lines of active galactic nuclei

    NASA Technical Reports Server (NTRS)

    Chen, Kaiyou; Halpern, Jules P.

    1990-01-01

    Previously, it was claimed that the broad emission lines of the radio galaxy Arp 102B can be fitted by the line profile from a simple relativistic Keplerian thin disk. It was argued that the lines originating from the relativistic accretion disk could be polarized due to electron scattering, which is likely to be the dominant opacity in the line-emitting region of Arp 102B. In the present work, the expected polarization properties of these broad emission lines are calculated. The percentage of polarization depends strongly on the inclination angle. For some angles, the red peak of the polarized, double-peaked line profile can be higher than the blue peak. This is in contrast to the total line profile, in which the blue peak is always higher than the red one. Spectropolarimetric observations could, therefore, provide an independent test of the relativistic disk model for the broad emission lines of Arp 102B and other active galactic nuclei.

  7. Simultaneous NuSTAR - XMM-Newton observations of AGN

    NASA Astrophysics Data System (ADS)

    Gokus, Andrea; Schartel, Norbert; Santos-Lleo, Maria; Wilms, Jörn; Fürst, Felix; Ballhausen, Ralf

    2016-08-01

    With the launch of NuSTAR in 2012, for the first time spatially resolved observations in the hard X-ray region, far beyond 10 keV, have become possible. NASA's NuSTAR observes from 4 keV to 80 keV. Many observations of NuSTAR are performed simultaneously with ESA's XMM-Newton X-ray observatory whichobserves from 0.3 keV to 12 keV. The soft and hard X-ray spectra together allow determining the continuum, absorption, reflection and emission lines. The broad band coverage of XMM and NuSTAR allows to resolve degeneracies between different spectral components. Joint bservations of the two satellites have become the main tool to study the iron K alpha line emission in the direct environment of black holes. In this region, relativistic effects distort the line profile allowing, amongst others, to constrain the primary X-ray emission region and the spin of supermassive black holes in AGN. The present study aims for the first time to analyze all available simultaneous NuSTAR - XMM-Newton observations in a coherent way with the aim to improve the cross-calibration and characterize physical content of public data.

  8. 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.

  9. 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.

  10. Properties of long-term optical variability of active galactic nuclei with double-peaked broad low-ionization emission lines

    NASA Astrophysics Data System (ADS)

    Zhang, Xue-Guang; Feng, Long-Long

    2016-10-01

    In this manuscript, we study properties of long-term optical variability of a large sample of 106 SDSS spectroscopically confirmed AGN with double-peaked broad low-ionization emission lines (double-peaked emitters). The long-term optical light curves over 8 years are collected from the Catalina Sky Surveys Data Release 2. And, the Damped Random Walk (DRW) process is applied to describe the long-term variability of the double-peaked emitters. Meanwhile, the same DRW process is applied to long-term optical light curves of more than 7000 spectroscopically confirmed normal quasars in the SDSS Stripe82 Database. Then, we can find that the DRW process determined rest-frame intrinsic variability timescales ln (τ/days) are about 5.8 and about 4.8 for the double-peaked emitters and for the normal quasars, respectively. The statistically longer intrinsic variability timescales can be confirmed in the double-peaked emitters, after considerations of necessary effects, such as the effects from different distributions of redshift, BH mass and accretion rate between the double-peaked emitters and the normal quasars. Moreover, a radial dependence of accretion rate dot{m}_R ∝ R^β with larger values of β could be an acceptable interpretation of the longer intrinsic variability timescales in the double-peaked emitters. Therefore, there are different intrinsic properties of emission regions between the double-peaked emitters and the normal quasars. The double-peaked emitters can be well treated as an unique subclass of AGN.

  11. DOUBLE-PEAKED NARROW-LINE ACTIVE GALACTIC NUCLEI. II. THE CASE OF EQUAL PEAKS

    SciTech Connect

    Smith, K. L.; Shields, G. A.; Salviander, S.; Stevens, A. C.; Rosario, D. J. E-mail: shields@astro.as.utexas.edu E-mail: acs0196@mail.utexas.edu

    2012-06-10

    Active galactic nuclei (AGNs) with double-peaked narrow lines (DPAGNs) may be caused by kiloparsec-scale binary AGNs, bipolar outflows, or rotating gaseous disks. We examine the class of DPAGNs in which the two narrow-line components have closely similar intensity as being especially likely to involve disks or jets. Two spectroscopic indicators support this likelihood. For DPAGNs from Smith et al., the 'equal-peaked' objects (EPAGNs) have [Ne V]/[O III]ratios lower than for a control sample of non-double-peaked AGNs. This is unexpected for a pair of normal AGNs in a galactic merger, but may be consistent with [O III] emission from a rotating ring with relatively little gas at small radii. Also, [O III]/H{beta} ratios of the redshifted and blueshifted systems in the EPAGN are more similar to each other than in a control sample, suggestive of a single ionizing source and inconsistent with the binary interpretation.

  12. Broad-line region structure and kinematics in the radio galaxy 3C 120

    NASA Astrophysics Data System (ADS)

    Kollatschny, W.; Ulbrich, K.; Zetzl, M.; Kaspi, S.; Haas, M.

    2014-06-01

    Context. Broad emission lines originate in the surroundings of supermassive black holes in the centers of active galactic nuclei (AGN). These broad-line emitting regions are spatially unresolved even for the nearest AGN. The origin and geometry of broad-line region (BLR) gas and their connection with geometrically thin or thick accretion disks is of fundamental importance for the understanding of AGN activity. Aims: One method to investigate the extent, structure, and kinematics of the BLR is to study the continuum and line profile variability in AGN. We selected the radio-loud Seyfert 1 galaxy 3C 120 as a target for this study. Methods: We took spectra with a high signal-to-noise ratio of 3C 120 with the 9.2 m Hobby-Eberly Telescope between Sept. 2008 and March 2009. In parallel, we photometrically monitored the continuum flux at the Wise observatory. We analyzed the continuum and line profile variations in detail (1D and 2D reverberation mapping) and modeled the geometry of the line-emitting regions based on the line profiles. Results: We show that the BLR in 3C 120 is stratified with respect to the distance of the line-emitting regions from the center with respect to the line widths (FWHM) of the rms profiles and with respect to the variability amplitude of the emission lines. The emission line wings of Hα and Hβ respond much faster than their central region. This is explained by accretion disk models. In addition, these lines show a stronger response in the red wings. However, the velocity-delay maps of the helium lines show a stronger response in the blue wing. Furthermore, the He ii λ4686 line responds faster in the blue wing in contradiction to observations made one and a half years later when the galaxy was in a lower state. The faster response in the blue wing is an indication for central outflow motions when this galaxy was in a bright state during our observations. The vertical BLR structure in 3C 120 coincides with that of other AGN. We confirm the

  13. AGN feedback on the ISM of 3C 236

    NASA Astrophysics Data System (ADS)

    Labiano, A.; García-Burillo, S.; Combes, F.; Usero, A.; Soria-Ruiz, R.; Tremblay, G.; Neri, R.; Fuente, A.; Morganti, R.; Oosterloo, T.

    2013-03-01

    We have carried out 1mm/3mm continuum and 12CO(2-1) line high resolution observations to identify the footprints of AGN feedback on 3C 236. The CO emission comes from a spatially resolved disk characterized by a regular rotating pattern. Within the limits imposed by the sensitivity and velocity coverage of our data, we do not detect any outflow signatures in the cold molecular gas. Re-inspection of optical and IR spectra, shows the presence of a previously unknown ionized gas outflow. The star-formation efficiency in 3C 236, is consistent with the value measured in normal galaxies, which follow the canonical Kennicutt-Schmidt law. This result, confirmed to hold in other young radio sources examined in this work, is in stark contrast with the factor of 10-50 lower SFE that has been claimed to characterize evolved powerful radio galaxies. The recent reactivation of the AGN in 3C 236 is a likely explanation for the early evolutionary status of its molecular disk.

  14. Spectroscopic survey of emission-line stars - I. B[e] stars

    NASA Astrophysics Data System (ADS)

    Aret, A.; Kraus, M.; Šlechta, M.

    2016-02-01

    Emission-line stars are typically surrounded by dense circumstellar material, often in form of rings or disc-like structures. Line emission from forbidden transitions trace a diversity of density and temperature regimes. Of particular interest are the forbidden lines of [O I] λλ6300, 6364 and [Ca II] λλ7291, 7324. They arise in complementary, high-density environments, such as the inner-disc regions around B[e] supergiants. To study physical conditions traced by these lines and to investigate how common they are, we initiated a survey of emission-line stars. Here, we focus on a sample of nine B[e] stars in different evolutionary phases. Emission of the [O I] lines is one of the characteristics of B[e] stars. We find that four of the objects display [Ca II] line emission: for the B[e] supergiants V1478 Cyg and 3 Pup, the kinematics obtained from the [O I] and [Ca II] line profiles agrees with a Keplerian rotating disc scenario; the forbidden lines of the compact planetary nebula OY Gem display no kinematical broadening beyond spectral resolution; the luminous blue variable candidate V1429 Aql shows no [O I] lines, but the profile of its [Ca II] lines suggests that the emission originates in its hot, ionized circumbinary disc. As none of the B[e] stars of lower mass displays [Ca II] line emission, we conclude that these lines are more likely observable in massive stars with dense discs, supporting and strengthening the suggestion that their appearance requires high-density environments.

  15. Stellar population properties for a sample of hard X-ray AGNs

    NASA Astrophysics Data System (ADS)

    Morelli, L.; Calvi, V.; Masetti, N.; Parisi, P.; Landi, R.; Maiorano, E.; Minniti, D.; Galaz, G.

    2013-08-01

    Aims: The aim of this paper is to study the stellar population of galaxies hosting an active galactic nucleus (AGN). We studied a subsample of hard X-ray emitting AGNs from the INTEGRAL and Swift catalogs, which were previously identified and characterized through optical spectroscopy. Our analysis provides complementary information, namely age and metallicity, which is necessary to complete the panoramic view of these interesting objects. Methods: We selected hard X-ray emitting objects, identified as AGNs, by checking their optical spectra in search of absorption lines suitable for the stellar population analysis. We obtained a final sample consisting of 20 objects with a redshift lower than 0.3. We used the full-spectrum fitting method; particularly, we use penalized pixel method and apply the PPXF code. After masking all the regions affected by emission lines, we fitted the spectra with the MILES single stellar population templates, and we derived mass-weighted ages and metallicities. Results: Most of the objects in our sample show an old stellar population; however, three of them are characterized by a bimodal distribution with a non-negligible contribution from young stars. The values of the mass-weighted metallicity span a wide range with most of them slightly above the solar value. No relations between the stellar population properties and the morphological ones have been found. Table 1 and Figs. 3-5 are available in electronic form at http://www.aanda.org

  16. 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.

  17. Atomic emission lines in the near ultraviolet; hydrogen through krypton, section 1

    NASA Technical Reports Server (NTRS)

    Kelly, R. L.

    1979-01-01

    A compilation of spectra from the first 36 elements was prepared from published literature available through October 1977. In most cases, only those lines which were actually observed in emission or absorption are listed. The wavelengths included range from 2000 Angstroms to 3200 Angstroms with some additional lines up to 3500 Angstroms. Only lines of stripped atoms are reported; no molecular bands are included.

  18. Atomic emission lines in the near ultraviolet; hydrogen through krypton, section 2

    NASA Technical Reports Server (NTRS)

    Kelly, R. L.

    1979-01-01

    A compilation of spectra from the first 36 elements was prepared from published literature available through October 1977. In most cases, only those lines which were actually observed in emission or absorption are listed. The wavelengths included range from 2000 Angstroms to 3200 Angstroms with some additional lines up to 3500 Angstroms. Only lines of stripped atoms are reported; no molecular bands are included.

  19. KILOPARSEC-SCALE PROPERTIES OF EMISSION-LINE GALAXIES

    SciTech Connect

    Hemmati, Shoubaneh; Miller, Sarah H.; Mobasher, Bahram; Nayyeri, Hooshang; Ferguson, Henry C.; Koekemoer, Anton M.; Guo, Yicheng; Koo, David C.

    2014-12-20

    We perform a detailed study of the resolved properties of emission-line galaxies at kiloparsec scales to investigate how small-scale and global properties of galaxies are related. We use a sample of 119 galaxies in the GOODS fields. The galaxies are selected to cover a wide range in morphologies over the redshift range 0.2 < z < 1.3. High resolution spectroscopic data from Keck/DEIMOS observations are used to fix the redshift of all the galaxies in our sample. Using the HST/ACS and HST/WFC3 imaging data taken as a part of the CANDELS project, for each galaxy, we perform spectral energy distribution fitting per resolution element, producing resolved rest-frame U – V color, stellar mass, star formation rate (SFR), age, and extinction maps. We develop a technique to identify ''regions'' of statistical significance within individual galaxies, using their rest-frame color maps to select red and blue regions, a broader definition for what are called ''clumps'' in other works. As expected, for any given galaxy, the red regions are found to have higher stellar mass surface densities and older ages compared to the blue regions. Furthermore, we quantify the spatial distribution of red and blue regions with respect to both redshift and stellar mass, finding that the stronger concentration of red regions toward the centers of galaxies is not a significant function of either redshift or stellar mass. We find that the ''main sequence'' of star-forming galaxies exists among both red and blue regions inside galaxies, with the median of blue regions forming a tighter relation with a slope of 1.1 ± 0.1 and a scatter of ∼0.2 dex compared to red regions with a slope of 1.3 ± 0.1 and a scatter of ∼0.6 dex. The blue regions show higher specific SFRs (sSFRs) than their red counterparts with the sSFR decreasing since z ∼ 1, driven primarily by the stellar mass surface densities rather than the SFRs at a given resolution element.

  20. Broad-line active galactic nuclei rotate faster than narrow-line ones.

    PubMed

    Kollatschny, Wolfram; Zetzl, Matthias

    2011-02-17

    The super-massive black holes of 10(6)M(⊙) to 10(9)M(⊙) that reside in the nuclei of active galaxies (AGN) are surrounded by a region emitting broad lines, probably associated with an accretion disk. The diameters of the broad-line regions range from a few light-days to more than a hundred light-days, and cannot be resolved spatially. The relative significance of inflow, outflow, rotational or turbulent motions in the broad-line regions as well as their structure (spherical, thin or thick accretion disk) are unknown despite intensive studies over more than thirty years. Here we report a fundamental relation between the observed emission linewidth full-width at half-maximum (FWHM) and the emission line shape FWHM/σ(line) in AGN spectra. From this relation we infer that the predominant motion in the broad-line regions is Keplerian rotation in combination with turbulence. The geometry of the inner region varies systematically with the rotation velocity: it is flattest for the fast-rotating broad-line objects, whereas slow-rotating narrow-line AGN have a more spherical structure. Superimposed is the trend that the line-emitting region becomes geometrically thicker towards the centre within individual galaxies. Knowing the rotational velocities, we can derive the central black-hole masses more accurately; they are two to ten times smaller than has been estimated previously.

  1. An atlas of Doppler emission-line tomography of cataclysmic variable stars

    NASA Technical Reports Server (NTRS)

    Kaitchuck, Ronald H.; Schlegel, Eric M.; Honeycutt, R. Kent; Horne, Keith; Marsh, T. R.; White, J. C., II; Mansperger, Cathy S.

    1994-01-01

    Doppler emission-line tomography is a technique similar to medical tomography. In this atlas the emission-line profiles of cataclysmic variable stars, seen at different orbital phases, are transformed into velocity space images. This transformation makes many of the complex line profile changes easier to interpret. The emission contributions of the disk and the s-wave are clearly separated in these images, and any emission from the stream and the secondary star can often be identified. In this atlas, Doppler tomograms of Hbeta, He I lambda 4471, and He II lambda 4686 emission lines of 18 cataclysmic variable stars are presented. The Doppler images provide insights into the individual systems and a better technique for measuring and radial velocity amplitude of the white dwarf.

  2. Emission line eclipse mapping of velocity fields in dwarf nova accretion discs

    NASA Astrophysics Data System (ADS)

    Makita, M.; Mineshige, S.

    2002-01-01

    We propose a new method, emission-line eclipse mapping, to map the velocity fields in an accretion disc. We apply the usual eclipse mapping technique to the light curves at each of 12-24 wavelengths across the line center to map the region with same line-of-sight velocity, from which we are able to plot the rotational velocity as a function of radius on the assumption of axisymmetric disc. We calculate time changes of the emission line profiles, assuming Keplerian rotation fields (vvarphi propto r-1/2) and the emissivity distribution of j propto r-3/2, and reconstruct emissivity profiles. The results show typically a `two-eye' pattern for high line-of-sight velocities and we can recover the relation, vvarphi propto d-1/2, where d is the separation of two lq eyes.'

  3. The star formation and AGN luminosity relation: predictions from a semi-analytical model

    NASA Astrophysics Data System (ADS)

    Gutcke, Thales A.; Fanidakis, Nikos; Macciò, Andrea V.; Lacey, Cedric

    2015-08-01

    In a universe where active galactic nucleus (AGN) feedback regulates star formation in massive galaxies, a strong correlation between these two quantities is expected. If the gas causing star formation is also responsible for feeding the central black hole, then a positive correlation is expected. If powerful AGNs are responsible for the star formation quenching, then a negative correlation is expected. Observations so far have mainly found a mild correlation or no correlation at all [i.e. a flat relation between star formation rate (SFR) and AGN luminosity], raising questions about the whole paradigm of `AGN feedback'. In this paper, we report the predictions of the GALFORM semi-analytical model, which has a very strong coupling between AGN activity and quenching of star formation. The predicted SFR-AGN luminosity correlation appears negative in the low AGN luminosity regime, where AGN feedback acts, but becomes strongly positive in the regime of the brightest AGN. Our predictions reproduce reasonably well recent observations by Rosario et al., yet there is some discrepancy in the normalization of the correlation at low luminosities and high redshifts. Though this regime could be strongly influenced by observational biases, we argue that the disagreement could be ascribed to the fact that GALFORM neglects AGN variability effects. Interestingly, the galaxies that dominate the regime where the observations imply a weak correlation are massive early-type galaxies that are subject to AGN feedback. Nevertheless, these galaxies retain high enough molecular hydrogen contents to maintain relatively high SFRs and strong infrared emission.

  4. 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.

  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. A TENTATIVE SIZE-LUMINOSITY RELATION FOR THE IRON EMISSION-LINE REGION IN QUASARS

    SciTech Connect

    Chelouche, Doron; Rafter, Stephen E.; Cotlier, Gabriel I.; Kaspi, Shai; Barth, Aaron J. E-mail: rafter@physics.technion.ac.il E-mail: barth@uci.edu

    2014-03-10

    New reverberation mapping measurements of the size of the optical iron emission-line region in quasars are provided, and a tentative size-luminosity relation for this component is reported. Combined with lag measurements in low-luminosity sources, the results imply an emission-region size that is comparable to and at most twice that of the Hβ line, and is characterized by a similar luminosity dependence. This suggests that the physics underlying the formation of the optical iron blends in quasars may be similar to that of other broad emission lines.

  7. Skylab ultraviolet stellar spectra - Emission lines from the Beta Lyrae system

    NASA Technical Reports Server (NTRS)

    Kondo, Y.; Parsons, S. B.; Wray, J. D.; Benedict, G. F.; Henize, K. G.; Mccluskey, G. E.

    1976-01-01

    Observations of Beta Lyr with the Skylab S-019 ultraviolet objective-prism spectrograph show numerous emission lines in the region from 1400 to 2300 A. Some variations in line strength between phases 0.25 and 0.50 are seen, which probably explain the shallowness of the OAO-2 light curve at 1910 A. Many of the emission lines are probably due to intercombination transitions, thus confirming the concept that the emission is produced by collisional excitation in low-density clouds of hot gas.

  8. Laboratory Measurements of the X-ray Line Emission from Neon-like Fe XVII

    NASA Technical Reports Server (NTRS)

    Brown, G. V.; Beiersdorfer, P.; Chen, H.; Scofield, J. H.; Boyce, K. R.; Kelley, R. L.; Kilbourne, C. A.; Porter, F. S.; Gu, M. F.; Kahn, S. M.

    2006-01-01

    We have conducted a systematic study of the dominant x-ray line emission from Fe XVII. These studies include relative line intensities in the optically thin limit, intensities in the presence of radiation from satellite lines from lower charge states of iron, and the absolute excitation cross sections of some of the strongest lines. These measurements were conducted at the Lawrence Livermore National Laboratory electron beam ion trap facility using crystal spectrometers and a NASA-Goddard Space Flight Center microcalorimeter array.

  9. Molecular line emission in asymmetric envelopes of evolved stars

    NASA Astrophysics Data System (ADS)

    Sanchez, Andres Felipe Perez

    2014-06-01

    Stars with initial masses of 0.8 < M⊙ < 9M⊙ eject most of their mass when evolving along the asymptotic giant branch (AGB) phase. The ejected material eventually cools down, which leads it to condensate and to form dust grains and molecular gas around the star, creating an extended circumstellar envelope (CSE). The mechanism responsible for the expansion of the dusty and dense CSEs is not completely understood. It is suggested that stellar radiation pressure on the dust particles can accelerate them outwards. Then, by collisional exchange of momentum, the dust particles drag along the molecular gas. However, this scenario cannot explain the onset of asymmetries in the CSEs observed towards more evolved sources such as post-AGB sources and Planetary nebulae. Part of the research in this thesis is focused on the study of the role that the stellar magnetic field plays on the formation of the collimated high-velocity outflows observed towards post-AGB sources. Polarized maser emission towards (post-)AGB stars has become an useful tool to determine the properties of the stellar magnetic fields permeating their CSEs. However, the polarization fraction detected can be affected by non-Zeeman effects. Here I present the results of our analysis of the polarization properties of SiO, H2O and HCN maser emission in the (sub-)millimetre wavelength range. The goal of this analysis is to determine whether polarized maser emission of these molecular species can be used as reliable tracer of the magnetic field from observations at (sub-)millimetre wavelengths. I also present the results of radio interferometric observations of both continuum and polarized maser emission towards post-AGB stars. The sources observed are characterized by H2O maser emission arising from their collimated, high-velocity outflows. The observations have been carried out with the Australian Telescope Compact Array aiming to detect both polarized maser emission and non-thermal radio continuum emission

  10. A Suzaku Observation of the Neutral Fe-line Emission from RCW 86

    NASA Technical Reports Server (NTRS)

    Ueno, Masaru; Sato, Rie; Kataoka, Jun; Bamba, Aya; Harrus, Ilana; Hiraga, Junko; Hughes, John P.; Kilbourne, Caroline A.; Koyama, Katsuji; Kokubun, Motohide; Nakajima, Hiroshi; Ozaki, Masanobu; Petre, Robert; Takahashi, Tadayuki; Tanaka, Takaaki; Tomida, Hiroshi; Yamaguchi, Hiroya

    2007-01-01

    The newly operational X-ray satellite Suzaku observed the supernova remnant (SNR) RCW 86 in February 2006 to study the nature of the 6.4 keV emission line first detected with the Advanced Satellite for Cosmology and Astronomy (ASCA). The new data confirms the existence of the line, localizing it for the first time inside a low temperature emission region and not at the locus of the continuum hard X-ray emission. We also report the first detection of a 7.1 keV line that we interpret as the K(beta) emission from neutral or low-ionized iron. The Fe-K line features are consistent with a non-equilibrium plasma of Fe-rich ejecta with n(sub e) less than or approx. equal to 10(exp 9)/cu cm s and kT(sub e) > 1 keV. We found a sign that Fe K(alpha) line is intrinsically broadened 47 (35-57) eV (99% error region). Cr-K line is also marginally detected, which is supporting the ejecta origin for the Fe-K line. By showing that the hard continuum above 3 keV has different spatial distribution from the Fe-K line, we confirmed it to be synchrotron X-ray emission.

  11. Theoretical quasar emission-line ratios. VII - Energy-balance models for finite hydrogen slabs

    NASA Technical Reports Server (NTRS)

    Hubbard, E. N.; Puetter, R. C.

    1985-01-01

    The present energy balance calculations for finite, isobaric, hydrogen-slab quasar emission line clouds incorporate probabilistic radiative transfer (RT) in all lines and bound-free continua of a five-level continuum model hydrogen atom. Attention is given to the line ratios, line formation regions, level populations and model applicability results obtained. H lines and a variety of other considerations suggest the possibility of emission line cloud densities in excess of 10 to the 10th/cu cm. Lyman-beta/Lyman-alpha line ratios that are in agreement with observed values are obtained by the models. The observed Lyman/Balmer ratios can be achieved with clouds whose column depths are about 10 to the 22nd/sq cm.

  12. NuSTAR Resolves the First Dual AGN above 10 keV in SWIFT J2028.5+2543

    NASA Astrophysics Data System (ADS)

    Koss, Michael J.; Glidden, Ana; Baloković, Mislav; Stern, Daniel; Lamperti, Isabella; Assef, Roberto; Bauer, Franz; Ballantyne, David; Boggs, Steven E.; Craig, William W.; Farrah, Duncan; Fürst, Felix; Gandhi, Poshak; Gehrels, Neil; Hailey, Charles J.; Harrison, Fiona A.; Markwardt, Craig; Masini, Alberto; Ricci, Claudio; Treister, Ezequiel; Walton, Dominic J.; Zhang, William W.

    2016-06-01

    We have discovered heavy obscuration in the dual active galactic nucleus (AGN) in the Swift/Burst Alert Telescope (BAT) source SWIFT J2028.5+2543 using Nuclear Spectroscopic Telescope Array (NuSTAR). While an early XMM-Newton study suggested the emission was mainly from NGC 6921, the superior spatial resolution of NuSTAR above 10 keV resolves the Swift/BAT emission into two sources associated with the nearby galaxies MCG +04-48-002 and NGC 6921 (z = 0.014) with a projected separation of 25.3 kpc (91″). NuSTAR's sensitivity above 10 keV finds both are heavily obscured to Compton-thick levels (N H ≈ (1-2) × 1024 cm-2) and contribute equally to the BAT detection ({L}10-50 {keV}{{int}} ≈ 6 × 1042 erg s-1). The observed luminosity of both sources is severely diminished in the 2-10 keV band ({L} 2-10 {keV}{{obs}}\\lt 0.1× {L} 2-10 {keV}{{int}}), illustrating the importance of >10 keV surveys like those with NuSTAR and Swift/BAT. Compared to archival X-ray data, MCG +04-48-002 shows significant variability (>3) between observations. Despite being bright X-ray AGNs, they are difficult to detect using optical emission-line diagnostics because MCG +04-48-002 is identified as a starburst/composite because of the high rates of star formation from a luminous infrared galaxy while NGC 6921 is only classified as a LINER using line detection limits. SWIFT J2028.5+2543 is the first dual AGN resolved above 10 keV and is the second most heavily obscured dual AGN discovered to date in the X-rays other than NGC 6240.

  13. NuSTAR Resolves the First Dual AGN above 10 keV in SWIFT J2028.5+2543

    NASA Astrophysics Data System (ADS)

    Koss, Michael J.; Glidden, Ana; Baloković, Mislav; Stern, Daniel; Lamperti, Isabella; Assef, Roberto; Bauer, Franz; Ballantyne, David; Boggs, Steven E.; Craig, William W.; Farrah, Duncan; Fürst, Felix; Gandhi, Poshak; Gehrels, Neil; Hailey, Charles J.; Harrison, Fiona A.; Markwardt, Craig; Masini, Alberto; Ricci, Claudio; Treister, Ezequiel; Walton, Dominic J.; Zhang, William W.

    2016-06-01

    We have discovered heavy obscuration in the dual active galactic nucleus (AGN) in the Swift/Burst Alert Telescope (BAT) source SWIFT J2028.5+2543 using Nuclear Spectroscopic Telescope Array (NuSTAR). While an early XMM-Newton study suggested the emission was mainly from NGC 6921, the superior spatial resolution of NuSTAR above 10 keV resolves the Swift/BAT emission into two sources associated with the nearby galaxies MCG +04-48-002 and NGC 6921 (z = 0.014) with a projected separation of 25.3 kpc (91″). NuSTAR's sensitivity above 10 keV finds both are heavily obscured to Compton-thick levels (N H ≈ (1–2) × 1024 cm‑2) and contribute equally to the BAT detection ({L}10-50 {keV}{{int}} ≈ 6 × 1042 erg s‑1). The observed luminosity of both sources is severely diminished in the 2–10 keV band ({L} 2-10 {keV}{{obs}}\\lt 0.1× {L} 2-10 {keV}{{int}}), illustrating the importance of >10 keV surveys like those with NuSTAR and Swift/BAT. Compared to archival X-ray data, MCG +04-48-002 shows significant variability (>3) between observations. Despite being bright X-ray AGNs, they are difficult to detect using optical emission-line diagnostics because MCG +04-48-002 is identified as a starburst/composite because of the high rates of star formation from a luminous infrared galaxy while NGC 6921 is only classified as a LINER using line detection limits. SWIFT J2028.5+2543 is the first dual AGN resolved above 10 keV and is the second most heavily obscured dual AGN discovered to date in the X-rays other than NGC 6240.

  14. Emission Line Spectra in the Soft X-ray Region 20 - 75 Angstroms

    NASA Technical Reports Server (NTRS)

    Lepson, J. K.; Beiersdorfer, P.; Chen, H.; Behar, E.; Kahn, S. M.

    2002-01-01

    As part of a project to complete a comprehensive catalogue of astrophysically relevant emission lines in support of new-generation X-ray observatories using the Lawrence Livermore electron beam ion traps EBIT-I and EDIT-II, emission lines of argon and sulfur in the soft X-ray and extreme ultraviolet region were studied. Observations of Ar IX through Ar XVI and S VII through S XIV between 20 and 75 Angstrom are presented to illustrate our work.

  15. Non-thermal 10 micrometers CO2 emission lines in the atmospheres of Mars and Venus

    NASA Technical Reports Server (NTRS)

    Johnson, M. A.

    1975-01-01

    Mechanisms for the excitation of strong 10 micrometer CO2 emission lines seen on Mars and Venus are examined. Line absorption of near IR solar flux directly by CO2 or by H2O with collisional transfer of energy to CO2 are proposed as likely excitation mechanisms. Altitudes for peak 10 micrometer emission are estimated to be near 80 km for Mars and 120 km for Venus.

  16. Nonthermal 10 micron CO2 emission lines in the atmospheres of Mars and Venus

    NASA Technical Reports Server (NTRS)

    Johnson, M. A.; Betz, A. L.; Mclaren, R. A.; Townes, C. H.; Sutton, E. C.

    1976-01-01

    Mechanisms are examined for excitation of strong 10-micron CO2 emission lines seen on Mars and Venus. Line absorption of near-infrared solar flux directly by CO2 or H2O with collisional transfer of energy to CO2 are proposed as likely excitation mechanisms. Altitudes for peak 10-micron emission are estimated to be near 80 km for Mars and 120 km for Venus.

  17. LZIFU: IDL emission line fitting pipeline for integral field spectroscopy data

    NASA Astrophysics Data System (ADS)

    Ho, I.-Ting

    2016-07-01

    LZIFU (LaZy-IFU) is an emission line fitting pipeline for integral field spectroscopy (IFS) data. Written in IDL, the pipeline turns IFS data to 2D emission line flux and kinematic maps for further analysis. LZIFU has been applied and tested extensively to various IFS data, including the SAMI Galaxy Survey, the Wide-Field Spectrograph (WiFeS), the CALIFA survey, the S7 survey and the MUSE instrument on the VLT.

  18. Search with Copernicus for ultraviolet emission lines in the planetary nebula NGC 3242

    NASA Technical Reports Server (NTRS)

    Schwartz, R. D.; Snow, T. P., Jr.; Upson, W. L., II

    1978-01-01

    The high-excitation planetary nebula NGC 3242 has been observed with the ultraviolet telescope-spectrometer aboard Copernicus. Wavelength intervals corresponding to the emission lines of O VI at 1032 A, He II at 1085 A, Si III at 1206 A, and N V at 1239 A have been scanned. Upper limits to the observed fluxes are reported and compared with predicted emission-line fluxes from this object.

  19. Virilization of the Broad Line Region in Active Galactic Nuclei—connection between shifts and widths of broad emission lines

    NASA Astrophysics Data System (ADS)

    Jonić, S.; Kovačević-Dojčinović, J.; Ilić, D.; Popović, L. Č.

    2016-03-01

    We investigate the virilization of the emission lines {Hβ } and Mg II in the sample of 287 Type 1 Active Galactic Nuclei taken from the Sloan Digital Sky Survey database. We explore the connections between the intrinsic line shifts and full widths at different levels of maximal intensity. We found that: (i) {Hβ} seems to be a good virial estimator of black hole masses, and an intrinsic redshift of {Hβ} is dominantly caused by the gravitational effect, (ii) there is an anti-correlation between the redshift and width of the wings of the Mg II line, (iii) the broad Mg II line can be used as virial estimator only at 50 % of the maximal intensity, while the widths and intrinsic shifts of the line wings cannot be used for this purpose.

  20. 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

  1. Accretion Disks and the Nature and Origin of AGN Continuum Variability

    NASA Astrophysics Data System (ADS)

    Gaskell, C. M.

    2008-04-01

    Theory and observations of the dominant thermal continuum emission in AGN are examined. After correction for reddening, the steady state AGN optical-UV spectral energy distributions (SEDs) are very similar. The SEDs are dominated energetically by the ``big blue bump'' (BBB), but this bump never shows the nu(+1/3) spectrum predicted for a standard thin accretion disk with a (r-0.75) radial temperature gradient. Instead, the observed optical-UV SED implies a temperature gradient of r(-0.57) independent of the thickness of the disk. This means that there is some flow of heat outwards in the disk. The disk is large and the region emitting the optical continuum is as large as the inner broad-line region (BLR). Because optical variability is seen in all AGN on the light-crossing time of the BLR, variations must propagate close to the speed of light, rather than on dynamical timescales. This argues that the energy-generation mechanism is electromagnetic rather that hydrodynamic. Since the velocities are near the speed of light, there can be significant local anisotropy in the emission. The large rapid variations of the BBB imply that the magnetohydrodynamic energy generation is fundamentally unstable. Because of the inevitable radial temperature gradient in the accreting material, different spectral regions come predominantly from different radii, and variations in different spectral regions correspond to variability at different radii. This explains the frequently observed independence of X-ray and optical variations, cases of variability at lower energies leading variability at higher energies, and rapid changes in emission-line reverberation lags. Some observational tests of the local variability hypothesis are proposed.

  2. The Dynamics and Radiative Properties of Clouds in Magnetized Accretion Disk Outflows in AGNs

    NASA Astrophysics Data System (ADS)

    Contopoulos, J.; Kartje, J. F.; Konigl, A.

    1996-05-01

    We have embarked on a general analysis of multi-component outflows from magnetized accretion disks in AGNs. In this scenario, dense diamagnetic clouds are embedded in a centrifugally driven wind and are uplifted from the disk surface by the dynamical drag of the wind as well as by the ``melon seed'' magnetic pressure gradient force. We follow the motion of the clouds above the disk surface, taking account of the radiation pressure force exerted by the central continuum. We consider both line and continuum radiation and investigate the effects of differing spectral energy distributions and degrees of emission isotropy on the cloud dynamics (comparing, e.g., the isotropic, thermal emission from QSOs with the beamed, nonthermal emission from a relativistic jet in BL Lac objects). We study the evolution of the clouds as they accelerate through the wind, considering possible sources of confinement (including magnetic stresses of the ambient field and hydrodynamic ram pressure), and estimating the cloud lifetimes against disruptive processes such as evaporation and dynamical instabilities. We also evaluate the impact of radiation pressure on the wind itself, via the force on dust grains in the wind and through the momentum transferred by the clouds. We examine the spectral signatures of accelerated clouds in the context of this dynamical scheme. Using the calculated velocity and ionization structure of the clouds throughout the flow, we compute absorption line profiles in the AGN continuum spectrum as a function of viewing angle through the wind. We apply our results to the interpretation of the observed optical/UV spectra from BALQSOs, and of the broad EUV and X-ray absorption features detected in a number of BL Lac objects. We also consider possible applications to other AGNs in which radiative acceleration of clouds has been inferred (e.g., ``warm absorber'' sources).

  3. Far-infrared line emission from the galaxy. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Stacey, G. J.

    1985-01-01

    The diffuse 157.74 micron (CII) emission from the Galaxy was sampled at several galactic longitudes near the galactic plane including complete scan across the plane at (II) = 2.16 deg and (II) = 7.28 deg. The observed (CII) emission profiles follow closely the nearby (12)CO (J=1to0) emission profiles. The (CII) emission probably arises in neutral photodissociation regions near the edges of giant moleclar clouds (GMC's). These regions have densities of approximately 350 cm(-3) and temperatures of approximately 300 K, and amount to 4x10(8) solar mass of hydrogen in the inner Galaxy. The total 157.74 micron luminosity of the Galaxy is estimated to be 6x10(7) solar luminosity. Estimates were also made of the galactic emission in other far-infrared (FIR) cooling lines. The (CII) line was found to be the dominant FIR emission line from the galaxy and the primary coolant for the warm neutral gas near the galactic plane. Other cooling lines predicted to be prominent in the galactic spectrum are discussed. The 145.53 micron (OI) emission line from the Orion nebula was also measured.

  4. Modelling line emission of deuterated H3+ from prestellar cores

    NASA Astrophysics Data System (ADS)

    Sipilä, O.; Hugo, E.; Harju, J.; Asvany, O.; Juvela, M.; Schlemmer, S.

    2010-01-01

    Context. The depletion of heavy elements in cold cores of interstellar molecular clouds can lead to a situation where deuterated forms of H3+ are the most useful spectroscopic probes of the physical conditions. Aims: The aim is to predict the observability of the rotational lines of H2D+ and D2H+ from prestellar cores. Methods: Recently derived rate coefficients for the H3+ + H2 isotopic system were applied to the “complete depletion” reaction scheme to calculate abundance profiles in hydrostatic core models. The ground-state lines of H2D+(o) (372 GHz) and D2H+(p) (692 GHz) arising from these cores were simulated. The excitation of the rotational levels of these molecules was approximated by using the state-to-state coefficients for collisions with H2. We also predicted line profiles from cores with a power-law density distribution advocated in some previous studies. Results: The new rate coefficients introduce some changes to the complete depletion model, but do not alter the general tendencies. One of the modifications with respect to the previous results is the increase of the D3+ abundance at the cost of other isotopologues. Furthermore, the present model predicts a lower H2D+ (o/p) ratio, and a slightly higher D2H+ (p/o) ratio in very cold, dense cores, as compared with previous modelling results. These nuclear spin ratios affect the detectability of the submm lines of H2D+(o) and D2H+(p). The previously detected H2D+ and D2H+ lines towards the core I16293E, and the H2D+ line observed towards Oph D can be reproduced using the present excitation model and the physical models suggested in the original papers.

  5. Emission lines in the spectra of the RV Tauri stars U Monocerotis and AC Herculis

    NASA Technical Reports Server (NTRS)

    Bopp, B. W.

    1984-01-01

    Strong metallic emission lines have been observed in the spectra of the RV Tauri stars U Mon and AC Her near recent light minima. While these two variables differ in a number of significant respects, the metallic emission spectra are quite similar, resembling the emission that was previously reported as present in the spectrum of R Sct at a deep minimum. The data appear to support Baird's shock-wave model for the spectral behavior of RV Tauri stars.

  6. EMISSION LINES BETWEEN 1 AND 2 keV IN COMETARY X-RAY SPECTRA

    SciTech Connect

    Ewing, Ian; Christian, Damian J.; Bodewits, Dennis; Dennerl, Konrad; Lisse, Carey M.; Wolk, Scott J. E-mail: daman.christian@csun.edu

    2013-01-20

    We present the detection of new cometary X-ray emission lines in the 1.0-2.0 keV range using a sample of comets observed with the Chandra X-Ray Observatory and ACIS spectrometer. We have selected five comets from the Chandra sample with good signal-to-noise spectra. The surveyed comets are C/1999 S4 (LINEAR), C/1999 T1 (McNaught-Hartley), 153P/2002 (Ikeya-Zhang), 2P/2003 (Encke), and C/2008 8P (Tuttle). We modeled the spectra with an extended version of our solar wind charge exchange (SWCX) emission model. Above 1 keV, we find Ikeya-Zhang to have strong emission lines at 1340 and 1850 eV which we identify as being created by SWCX lines of Mg XI and Si XIII, respectively, and weaker emission lines at 1470, 1600, and 1950 eV formed by SWCX of Mg XII, Mg XI, and Si XIV, respectively. The Mg XI and XII and Si XIII and XIV lines are detected at a significant level for the other comets in our sample (LS4, MH, Encke, 8P), and these lines promise additional diagnostics to be included in SWCX models. The silicon lines in the 1700-2000 eV range are detected for all comets, but with the rising background and decreasing cometary emission, we caution that these detections need further confirmation with higher resolution instruments.

  7. Excitation of emission lines by fluorescence and recombination in IC 418

    NASA Astrophysics Data System (ADS)

    Escalante, Vladimir; Morisset, Cristophe; Georgiev, Leonid

    2012-08-01

    We predict intensities of lines of CII, NI, NII, OI and OII and compare them with a deep spectroscopic survey of IC 418 to test the effect of excitation of nebular emission lines by continuum fluorescence of starlight. Our calculations use a nebular model and a synthetic spectrum of its central star to take into account excitation of the lines by continuum fluorescence and recombination. The NII spectrum is mostly produced by fluorescence due to the low excitation conditions of the nebula, but many CII and OII lines have more excitation by fluorescence than recombination. In the neutral envelope, the NI permitted lines are excited by fluorescence, and almost all the OI lines are excited by recombination. Electron excitation produces the forbidden optical lines of OI, but continuum fluorescence excites most of the NI forbidden line intensities. Lines excited by fluorescence of light below the Lyman limit thus suggest a new diagnostic to explore the photodissociation region of a nebula.

  8. 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.

  9. Multilayer mirror based line emission tomography for spherical Tokamaks

    SciTech Connect

    Stutman, D.; Hwang, Y.S.; Menard, J.; Choe, W.; Ono, M.; Finkenthal, M.; May, M.J.; Regan, S.P.; Soukhanovskii, V.; Moos, H.W.

    1997-01-01

    Due to their highly shaped plasma and possible poloidal asymmetry in impurity concentration, spherical Tokamaks will require tomographic reconstruction of local emissivities to assess impurity content and transport. To collect in an effective manner the data required for such reconstruction, we develop arrays of high throughput {open_quotes}mini-monochromators{close_quotes} using extreme ultraviolet multilayer mirrors as dispersive elements and filtered surface barrier diodes as detectors. We discuss monochromator optimization and show that by working at near normal incidence throughput and spectral resolution are simultaneously maximized. A system proposed for tomographic reconstruction of CV and CVI resonance emission at 33.7 and 40.5 {Angstrom} respectively, achieves 0.9 {Angstrom} spectral resolution, 2 cm spatial resolution, and 0.2 ms temporal resolution, together with good sensitivity and background rejection. Preliminary results obtained from CDX-U low aspect ratio tokamak are also presented. {copyright} {ital 1997 American Institute of Physics.}

  10. A Suzaku search for dark matter emission lines in the X-ray brightest galaxy clusters

    NASA Astrophysics Data System (ADS)

    Urban, O.; Werner, N.; Allen, S. W.; Simionescu, A.; Kaastra, J. S.; Strigari, L. E.

    2015-08-01

    We present the results of a search for unidentified emission lines in deep Suzaku X-ray spectra of the central regions of the X-ray brightest galaxy clusters: Perseus, Coma, Virgo and Ophiuchus. We analyse an optimized energy range (3.2-5.3 keV) that is relatively free of instrumental features, and a plasma emission model incorporating the abundances of elements with the strongest expected emission lines at these energies (S, Ar, Ca) as free parameters. For the Perseus Cluster core, employing this model, we find evidence for an additional emission feature at an energy E=3.51^{+0.02}_{-0.01} keV with a flux of 2.87_{-0.38}^{+0.33}× 10^{-7} photons s^{-1} cm^{-2} arcmin^{-2}. At slightly larger radii, we detect an emission line at 3.59 ± 0.02 keV with a flux of 4.8_{-1.4}^{+1.7}× 10^{-8} photons s^{-1} cm^{-2} arcmin^{-2}. The properties of these features are broadly consistent with previous claims, although the radial variation of the line strength appears in tension with dark matter (DM) decay model predictions. Assuming a decaying DM origin for these features allows us to predict the energies and detected line fluxes for the other clusters. We do not detect an emission feature at the predicted energy and line flux in the Coma, Virgo and Ophiuchus clusters. The formal 99.5 per cent upper limits on the line strengths in each cluster are well below the decaying DM model predictions, disfavouring a decaying DM interpretation. The results of further analysis suggest that systematic effects associated with modelling the spectra for the Perseus Cluster, details of the assumed ionization balance and errors in the predicted spectral line emissivities may be largely responsible for the ˜3.55 keV feature.

  11. Emission-Line Eclipse Mapping of Velocity Fields in a Dwarf-Nova Accretion Disk

    NASA Astrophysics Data System (ADS)

    Makita, Makoto; Mineshige, Shin

    2002-06-01

    We propose a new method, emission-line eclipse mapping, to map the velocity fields of an accretion disk in position space. Quiescent dwarf novae usually exhibit double-peaked emission-line profiles because of disk rotation. Since a part of a disk having a different line-of-sight velocity is successively obscured by a companion in eclipsing systems, they show time-varying line profiles. We calculated the time changes of the emission-line profiles, assuming Keplerian rotation fields (vφ ~ r-1/2 with r being the distance from the disk center) and an emissivity distribution of j ~ r-3/2. We, then, applied the usual eclipse mapping technique to the light curves at each of 12-24 wavelengths across the line center to map the region with the same line-of-sight velocity. The reconstructed images typically exhibit a `two-eye' pattern for high line-of-sight velocities, and we can recover the relation, vφ ~ d-1/2, on the assumption of an axisymmetric disk, where d is the separation between the two `eyes'. We will be able to probe the Keplerian rotation law, the most fundamental assumption adopted in many disk models, by high-speed spectroscopic observations with 8-m class telescopes.

  12. 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.

  13. Study of Opacity Effects on Emission Lines at EXTRAP T2R RFP

    NASA Astrophysics Data System (ADS)

    Stancalie, Viorica; Rachlew, Elisabeth

    We have investigated the influence of opacity on hydrogen (H-α and Ly-β) and Li-like oxygen emission lines from the EXTRAP T2R reversed field pinch. We used the Atomic Data Analysis System (AzDAS) based on the escape factor approximation for radiative transfer to calculate metastable and excited population densities via a collisional-radiative model. Population escape factor, emergent escape factor and modified line profiles are plotted vs. optical depth. The simulated emission line ratios in the density/temperature plane are in good agreement with experimental data for electron density and temperature measurements.

  14. Modeling X-ray emission line profiles from massive star winds - A review

    NASA Astrophysics Data System (ADS)

    Ignace, Richard

    2016-09-01

    The Chandra and XMM-Newton X-ray telescopes have led to numerous advances in the study and understanding of astrophysical X-ray sources. Particularly important has been the much increased spectral resolution of modern X-ray instrumentation. Wind-broadened emission lines have been spectroscopically resolved for many massive stars. This contribution reviews approaches to the modeling of X-ray emission line profile shapes from single stars, including smooth winds, winds with clumping, optically thin versus thick lines, and the effect of a radius-dependent photoabsorption coefficient.

  15. Variability of the emission line fluxes and ratios of HH 1/2

    NASA Astrophysics Data System (ADS)

    Raga, A. C.; Reipurth, B.; Castellanos-Ramírez, Bally, J.

    2016-04-01

    We compare spectrophotometric data of HH 1 and 2 obtained in 1978 (by Brugel et al. 1981a) with the emission line fluxes from calibrated Hubble Space Telescope (HST) images obtained in 1994 and 2014. This comparison shows that the emission line ratios of these objects have remained surprisingly invariant during the past 36 years. On the other hand, the line intensities have indeed changed, with HH 2 brightening by a factor of ≈ 4 and HH 1 becoming ≈ 30% fainter. These results would be consistent with HH 1 and 2 being leading working surfaces of heavy jets travelling into an environment of decreasing (for HH 1) or increasing (HH 2) densities.

  16. Temperature measurement of wood flame based on the double line method of atomic emission spectra

    NASA Astrophysics Data System (ADS)

    Hao, Xiaojian; Liu, Zhenhua; Sang, Tao

    2016-01-01

    Aimed at the testing requirement of the transient high temperature in explosion field and the bore of barrel weapon, the temperature measurement system of double line of atomic emission spectrum was designed, the method of flame spectrum testing system were used for experimental analysis. The experimental study of wood burning spectra was done with flame spectrum testing system. The measured spectra contained atomic emission spectra of the elements K, Na, and the excitation ease of two kinds atomic emission spectra was analyzed. The temperature was calculated with two spectral lines of K I 766.5nm and 769.9nm. The results show that, compared with Na, the excitation temperature of K atomic emission spectra is lower. By double line method, the temperature of wood burning is 1040K, and error is 3.7%.

  17. Dark matter line emission constraints from NuSTAR observations of the bullet cluster

    SciTech Connect

    Riemer-Sørensen, S.; Wik, D.; Madejski, G.; Molendi, S.; Gastaldello, F.; Harrison, F. A.; Craig, W. W.; Hailey, C. J.; Boggs, S. E.; Christensen, F. E.; Stern, D.; Zhang, W. W.; Hornstrup, A.

    2015-08-27

    Some dark matter candidates, e.g., sterile neutrinos, provide observable signatures in the form of mono-energetic line emission. Here, we present the first search for dark matter line emission in the $3-80\\;\\mathrm{keV}$ range in a pointed observation of the Bullet Cluster with NuSTAR. We do not detect any significant line emission and instead we derive upper limits (95% CL) on the flux, and interpret these constraints in the context of sterile neutrinos and more generic dark matter candidates. NuSTAR does not have the sensitivity to constrain the recently claimed line detection at $3.5\\;\\mathrm{keV}$, but improves on the constraints for energies of $10-25\\;\\mathrm{keV}$.

  18. Dark matter line emission constraints from NuSTAR observations of the bullet cluster

    DOE PAGES

    Riemer-Sørensen, S.; Wik, D.; Madejski, G.; Molendi, S.; Gastaldello, F.; Harrison, F. A.; Craig, W. W.; Hailey, C. J.; Boggs, S. E.; Christensen, F. E.; et al

    2015-08-27

    Some dark matter candidates, e.g., sterile neutrinos, provide observable signatures in the form of mono-energetic line emission. Here, we present the first search for dark matter line emission in themore » $$3-80\\;\\mathrm{keV}$$ range in a pointed observation of the Bullet Cluster with NuSTAR. We do not detect any significant line emission and instead we derive upper limits (95% CL) on the flux, and interpret these constraints in the context of sterile neutrinos and more generic dark matter candidates. NuSTAR does not have the sensitivity to constrain the recently claimed line detection at $$3.5\\;\\mathrm{keV}$$, but improves on the constraints for energies of $$10-25\\;\\mathrm{keV}$$.« less

  19. Physical Conditions in the X-Ray Emission-line Gas in NGC 1068

    NASA Astrophysics Data System (ADS)

    Kraemer, S. B.; Sharma, N.; Turner, T. J.; George, Ian M.; Crenshaw, D. Michael

    2015-01-01

    We present a detailed, photoionization modeling analysis of XMM-Newton/Reflection Grating Spectrometer observations of the Seyfert 2 galaxy NGC 1068. The spectrum, previously analyzed by Kinkhabwala et al., reveals a myriad of soft X-ray emission lines, including those from H- and He-like carbon, nitrogen, oxygen, and neon, and M- and L-shell iron. As noted in the earlier analysis, based on the narrowness of the radiative recombination continua, the electron temperatures in the emission-line gas are consistent with photoionization, rather than collisional ionization. The strengths of the carbon and nitrogen emission lines, relative to those of oxygen, suggest unusual elemental abundances, which we attribute to the star formation history of the host galaxy. Overall, the emission lines are blueshifted with respect to systemic, with radial velocities ~160 km s-1, similar to that of [O III] λ5007, and thus consistent with the kinematics and orientation of the optical emission-line gas and, hence, likely part of an active galactic nucleus driven outflow. We were able to achieve an acceptable fit to most of the strong emission lines with a two-component photoionization model, generated with CLOUDY. The two components have ionization parameters and column densities of logU = -0.05 and 1.22 and logN H = 20.85 and 21.2 and covering factors of 0.35 and 0.84, respectively. The total mass of the X-ray gas is roughly an order of magnitude greater than the mass of ionized gas determined from optical and near-IR spectroscopy, which indicates that it may be the dominant component of the narrow-line region. Furthermore, we suggest that the medium that produces the scattered/polarized optical emission in NGC 1068 possesses similar physical characteristics to those of the more highly ionized of the X-ray model components.

  20. PHYSICAL CONDITIONS IN THE X-RAY EMISSION-LINE GAS IN NGC 1068

    SciTech Connect

    Kraemer, S. B.; Sharma, N.; Turner, T. J.; George, Ian M.; Crenshaw, D. Michael

    2015-01-01

    We present a detailed, photoionization modeling analysis of XMM-Newton/Reflection Grating Spectrometer observations of the Seyfert 2 galaxy NGC 1068. The spectrum, previously analyzed by Kinkhabwala et al., reveals a myriad of soft X-ray emission lines, including those from H- and He-like carbon, nitrogen, oxygen, and neon, and M- and L-shell iron. As noted in the earlier analysis, based on the narrowness of the radiative recombination continua, the electron temperatures in the emission-line gas are consistent with photoionization, rather than collisional ionization. The strengths of the carbon and nitrogen emission lines, relative to those of oxygen, suggest unusual elemental abundances, which we attribute to the star formation history of the host galaxy. Overall, the emission lines are blueshifted with respect to systemic, with radial velocities ∼160 km s{sup –1}, similar to that of [O III] λ5007, and thus consistent with the kinematics and orientation of the optical emission-line gas and, hence, likely part of an active galactic nucleus driven outflow. We were able to achieve an acceptable fit to most of the strong emission lines with a two-component photoionization model, generated with CLOUDY. The two components have ionization parameters and column densities of logU = –0.05 and 1.22 and logN {sub H} = 20.85 and 21.2 and covering factors of 0.35 and 0.84, respectively. The total mass of the X-ray gas is roughly an order of magnitude greater than the mass of ionized gas determined from optical and near-IR spectroscopy, which indicates that it may be the dominant component of the narrow-line region. Furthermore, we suggest that the medium that produces the scattered/polarized optical emission in NGC 1068 possesses similar physical characteristics to those of the more highly ionized of the X-ray model components.

  1. Abell 262 and RXJ0341: Two Brightest Cluster Galaxies with Line Emission Blanketing a Cool Core

    NASA Astrophysics Data System (ADS)

    Edwards, Louise O. V.; Heng, Renita

    2014-08-01

    Over the last decade, integral field (IFU) analysis of the brightest cluster galaxies (BCGs) in several cool core clusters has revealed the central regions of these massive old red galaxies to be far from dead. Bright line emission alongside extended X-ray emission links nearby galaxies, is superposed upon vast dust lanes and extends out in long thin filaments from the galaxy core. Yet, to date no unifying picture has come into focus, and the activity across systems is currently seen as a grab-bag of possibile emission line mechanisms. Our primary goal is to work toward a consistent picture for why the BCGs seem are undergoing a renewed level of activity. One problem is most of the current data remains focused on mapping the very core of the BCG, but neglects surrounding galaxies. We propose to discover the full extent of line emission in a complementary pair of BCGs. In Abell 262, an extensive dust patch screens large portions of an otherwise smooth central galaxy, whereas RXJ0341 appears to be a double-core dust free BCG. We will map the full extent of the line emission in order to deduce whether the line emission is a product of local interactions, or the large-scale cluster X-ray gas. The narrow band filter set and large FOV afforded by the the Mayall MOSAIC-1 (MOSA) imager allows us to concurrently conduct an emission line survey of both clusters, locating all line emitting members and beginning a search for the effect of the environment of the different regions (outskirts vs. cluster core) out to the virial radius. We will combine our results with publically available data from 2MASS to determine the upper limits on specific star formation in the BCG and other cluster galaxies within the cluster virial radius.

  2. 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.

  3. Is There an Obscured AGN in the Normal Galaxy IRASF01063-8034

    NASA Technical Reports Server (NTRS)

    Greenhill, Lincoln J.

    2005-01-01

    The XMM target for this program is ostensibly a "normal" galaxy, but the presence of water maser emission indicated that it may be an obscured AGN. Our primary goal is to test this hypothesis; detection hard X-ray emission and a reflection-dominated spectrum would indicate an AGN is present. Demonstration that the local universe contains obscured AGN is important to constraining models of the hard cosmic X-ray background, as is identification of efficient methods to locate them (e.g., ground-based detection of maser emission at microwave frequencies).

  4. Anisotropic. cap alpha. -emission of on-line separated isotopes

    SciTech Connect

    Wouters, J.; Vandeplassche, D.; van Walle, E.; Severijns, N.; Van Haverbeke, J.; Vanneste, L.

    1987-12-10

    The technical realization of particle detection at very low temperatures (4K) has made it possible to study for the first time the anisotropic ..cap alpha..-decay of oriented nuclei which have been produced, separated and implanted on line. The measured ..cap alpha..-angular distributions reveal surprising new results on nuclear aspects as well as in solid state physics. The nuclear structure information from these data questions the older ..cap alpha..-decay theoretical interpretation and urges for a reaxamination of the earliest work on anisotropic ..cap alpha..-decay.

  5. GAS EXCITATION IN ULIRGs: MAPS OF DIAGNOSTIC EMISSION-LINE RATIOS IN SPACE AND VELOCITY

    SciTech Connect

    Soto, Kurt T.; Martin, Crystal L.

    2012-11-15

    Emission-line spectra extracted at multiple locations across 39 ultraluminous infrared galaxies have been compiled into a spectrophotometric atlas. Line profiles of H{alpha}, [N II], [S II], [O I], H{beta}, and [O III] are resolved and fit jointly with common velocity components. Diagnostic ratios of these line fluxes are presented in a series of plots, showing how the Doppler shift, line width, gas excitation, and surface brightness change with velocity at fixed position and also with distance from the nucleus. One general characteristic of these spectra is the presence of shocked gas extending many kiloparsecs from the nucleus. In some systems, the rotation curves of the emitting gas indicate motions that suggest gas disks, which are most frequent at early merger stages. At these early merger stages, the emission line ratios indicate the presence of shocked gas, which may be triggered by the merger event. We also report the general characteristics of the integrated spectra.

  6. A Search For C IV Emission Line From Galactic SNRs With SPEAR/FIMS

    NASA Astrophysics Data System (ADS)

    Kim, Il-Joong; Min, K.; Seon, K.; Korpela, E.; Edelstein, J.

    2009-12-01

    C IV λλ1548, 1551 lines are one of the most prominent emission lines in the FUV, which are expected to detect from supernova remnants. With the SPEAR/FIMS instrument, it has already been detected and analyzed about five large angular size supernova remnants, the Vela, the Cygnus Loop, the Lupus Loop, the Monogem Ring, and the Antlia SNR. Next, we searched for C IV emission line from other smaller size Galactic supernova remnants with the same instrument and found it for several targets. We also found some significant C IV emission line morphologies, which are clearly correlated with the X-ray, Hα, or radio morphologies for RCW 114, the Monoceros Loop, RX J0852.0-4622, G65.3+5.7, and G279.0+1.1. Additionally, while inspecting C IV emission morphology of RX J0852.0-4622 region, we found that the Vela is in direct contact with a Hα ring feature like the Monogem Ring is in direct contact with the Gemini Hα ring. We present the results of this searching and the early results of analyzing C IV emission line morphologies for several interesting targets.

  7. Dayglow Emission Line Profiles from the Outer Planets Cycle 4-MED Part 2 OF 5414

    NASA Astrophysics Data System (ADS)

    Clarke, John

    1994-01-01

    Recent IUE observations of the H Ly alpha emission line profilefrom Jupiter's dayglow and aurora reveal a substantial line broadening,implying that the observed high brightness is due to resonantscattering of solar emission with a broad line rather than chargedparticle excitation. This may reflect highly energetic processesproducing a 5-10 km/sec suprathermal population of H atoms in Jupiter'supper atmosphere, which in turn may be related to the unresolved questionof the high exospheric temperatures of 400-1200 K detected on all 4 giantplanets during the Voyager encounters. It is clear that if the bright HLy alpha emissions from the outer planets are due mainly to resonantscattering of solar and interplanetary emissions, as observedon Jupiter and Saturn from long term correlations with the solarLy alpha flux, then the lines from all 4 planets must be broad toexplain the observed high albedos. The H Ly alpha lineshapes providea discriminant between the processes of resonant scattering andcharged particle excitation. We propose to obtain high signal to noiseH Ly alpha line profile measurements from Saturn, Uranus, and Neptuneto resolve the questions about the excitation processes for the brightairglow emissions.SATURN PART ONLY - NEPTUNE AND URANUS IN ORIGIAL PROP (5414).

  8. X-RAY EMISSION LINE PROFILES FROM WIND CLUMP BOW SHOCKS IN MASSIVE STARS

    SciTech Connect

    Ignace, R.; Waldron, W. L.; Cassinelli, J. P.; Burke, A. E. E-mail: wwaldron@satx.rr.com E-mail: burke.alexander@gmail.com

    2012-05-01

    The consequences of structured flows continue to be a pressing topic in relating spectral data to physical processes occurring in massive star winds. In a preceding paper, our group reported on hydrodynamic simulations of hypersonic flow past a rigid spherical clump to explore the structure of bow shocks that can form around wind clumps. Here we report on profiles of emission lines that arise from such bow shock morphologies. To compute emission line profiles, we adopt a two-component flow structure of wind and clumps using two 'beta' velocity laws. While individual bow shocks tend to generate double-horned emission line profiles, a group of bow shocks can lead to line profiles with a range of shapes with blueshifted peak emission that depends on the degree of X-ray photoabsorption by the interclump wind medium, the number of clump structures in the flow, and the radial distribution of the clumps. Using the two beta law prescription, the theoretical emission measure and temperature distribution throughout the wind can be derived. The emission measure tends to be power law, and the temperature distribution is broad in terms of wind velocity. Although restricted to the case of adiabatic cooling, our models highlight the influence of bow shock effects for hot plasma temperature and emission measure distributions in stellar winds and their impact on X-ray line profile shapes. Previous models have focused on geometrical considerations of the clumps and their distribution in the wind. Our results represent the first time that the temperature distribution of wind clump structures are explicitly and self-consistently accounted for in modeling X-ray line profile shapes for massive stars.

  9. C IV emission-line properties and systematic trends in quasar black hole mass estimates

    NASA Astrophysics Data System (ADS)

    Coatman, Liam; Hewett, Paul C.; Banerji, Manda; Richards, Gordon T.

    2016-09-01

    Black hole masses are crucial to understanding the physics of the connection between quasars and their host galaxies and measuring cosmic black hole-growth. At high redshift, z ≳ 2.1, black hole masses are normally derived using the velocity width of the C IV λ λ1548, 1550 broad emission line, based on the assumption that the observed velocity widths arise from virial-induced motions. In many quasars, the C IV emission line exhibits significant blue asymmetries (`blueshifts') with the line centroid displaced by up to thousands of km s-1 to the blue. These blueshifts almost certainly signal the presence of strong outflows, most likely originating in a disc wind. We have obtained near-infrared spectra, including the Hα λ6565 emission line, for 19 luminous (LBol = 46.5-47.5 erg s-1) Sloan Digital Sky Survey quasars, at redshifts 2 < z < 2.7, with C IV emission lines spanning the full range of blueshifts present in the population. A strong correlation between C IV velocity width and blueshift is found and, at large blueshifts, >2000 km s-1, the velocity widths appear to be dominated by non-virial motions. Black hole masses, based on the full width at half-maximum of the C IV emission line, can be overestimated by a factor of 5 at large blueshifts. A larger sample of quasar spectra with both C IV and H β, or Hα, emission lines will allow quantitative corrections to C IV-based black hole masses as a function of blueshift to be derived. We find that quasars with large C IV blueshifts possess high Eddington luminosity ratios and that the fraction of high-blueshift quasars in a flux-limited sample is enhanced by a factor of approximately 4 relative to a sample limited by black hole mass.

  10. Obscured AGN at High Redshift

    NASA Technical Reports Server (NTRS)

    Stern, Daniel

    2008-01-01

    This viewgraph presentation reviews the obscured sources of Active Galactic Nuclei (AGN) in the universe at high redshift. The cosmic X-ray background, unified models of AGN and clues to galaxy formation/evolution is the motivation for this study.

  11. Fueling the central engine of radio galaxies. II. The footprints of AGN feedback on the ISM of 3C 236

    NASA Astrophysics Data System (ADS)

    Labiano, A.; García-Burillo, S.; Combes, F.; Usero, A.; Soria-Ruiz, R.; Tremblay, G.; Neri, R.; Fuente, A.; Morganti, R.; Oosterloo, T.

    2013-01-01

    Context. There is growing observational evidence of active galactic nuclei (AGN) feedback on the interstellar medium (ISM) of radio-quiet and radio-loud galaxies. While AGN feedback is expected to be more common at high-redshift objects, studying local universe galaxies helps to better characterize the different manifestations of AGN feedback. Aims: Molecular line observations can be used to quantify the mass and energy budget of the gas affected by AGN feedback. We study the emission of molecular gas in 3C 236, a Faranoff-Riley type 2 (FR II) radio source at z ~ 0.1, and search for the footprints of AGN feedback. The source 3C 236 shows signs of a reactivation of its AGN triggered by a recent minor merger episode. Observations have also previously identified an extreme H i outflow in this source. Methods: The IRAM Plateau de Bure interferometer (PdBI) was used to study the distribution and kinematics of molecular gas in 3C 236 by imaging with high spatial resolution (0.6″) the emission of the 2-1 line of 12CO in the nucleus of the galaxy. We searched for outflow signatures in the CO map. We also derived the star-formation rate (SFR) in 3C 236 using data available from the literature at UV, optical, and IR wavelengths, to determine the star-formation efficiency (SFE) of molecular gas. Results: The CO emission in 3C 236 comes from a spatially resolved ~1.4″(2.6 kpc-) diameter disk characterized by a regular rotating pattern. Within the limits imposed by the sensitivity and velocity coverage of the CO data, we do not detect any outflow signatures in the cold molecular gas. The disk has a cold gas mass M(H2) ~ 2.1 × 109 M⊙. Based on CO we determine a new value for the redshift of the source zCO = 0.09927 ± 0.0002. The similarity between the CO and H i profiles indicates that the deep H i absorption in 3C 236 can be accounted for by a rotating H i structure. This restricts the evidence of H i outflow to only the most extreme velocities. In the light of the new

  12. HERSCHEL-PACS OBSERVATIONS OF FAR-IR CO LINE EMISSION IN NGC 1068: HIGHLY EXCITED MOLECULAR GAS IN THE CIRCUMNUCLEAR DISK

    SciTech Connect

    Hailey-Dunsheath, S.; Sturm, E.; Gracia-Carpio, J.; Davies, R.; Poglitsch, A.; Contursi, A.; Genzel, R.; Lutz, D.; Tacconi, L.; De Jong, J. A.; Fischer, J.; Sternberg, A.; Mark, D.; Gonzalez-Alfonso, E.; Veilleux, S.; Verma, A.

    2012-08-10

    We report the detection of far-IR CO rotational emission from the prototypical Seyfert 2 galaxy NGC 1068. Using Herschel-PACS, we have detected 11 transitions in the J{sub upper} = 14-30 (E{sub upper}/k{sub B} = 580-2565 K) range, all of which are consistent with arising from within the central 10'' (700 pc). The detected transitions are modeled as arising from two different components: a moderate-excitation (ME) component close to the galaxy systemic velocity and a high-excitation (HE) component that is blueshifted by {approx}80 km s{sup -1}. We employ a large velocity gradient model and derive n{sub H2} {approx} 10{sup 5.6} cm{sup -3}, T{sub kin} {approx} 170 K, and M{sub H2} {approx} 10{sup 6.7} M{sub Sun} for the ME component and n{sub H2} {approx} 10{sup 6.4} cm{sup -3}, T{sub kin} {approx} 570 K, and M{sub H2} {approx} 10{sup 5.6} M{sub Sun} for the HE component, although for both components the uncertainties in the density and mass are {+-}(0.6-0.9) dex. Both components arise from denser and possibly warmer gas than traced by low-J CO transitions, and the ME component likely makes a significant contribution to the mass budget in the nuclear region. We compare the CO line profiles with those of other molecular tracers observed at higher spatial and spectral resolution and find that the ME transitions are consistent with these lines arising in the {approx}200 pc diameter ring of material traced by H{sub 2} 1-0 S(1) observations. The blueshift of the HE lines may also be consistent with the bluest regions of this H{sub 2} ring, but a better kinematic match is found with a clump of infalling gas {approx}40 pc north of the active galactic nucleus (AGN). We consider potential heating mechanisms and conclude that X-ray- or shock heating of both components is viable, while far-UV heating is unlikely. We discuss the prospects of placing the HE component near the AGN and conclude that while the moderate thermal pressure precludes an association with the {approx}1 pc

  13. Mid Infrared Hydrogen Recombination Line Emission from the Maser Star MWC 349A

    NASA Technical Reports Server (NTRS)

    Smith, Howard A.; Strelnitski, V.; Miles, J. W.; Kelly, D. M.; Lacy, J. H.

    1997-01-01

    We have detected and spectrally resolved the mid-IR hydrogen recombination lines H6(alpha)(12.372 micrometers), H7(alpha)(19.062 micrometers), H7(beta)(l1.309 micrometers) and H8(gamma)(12.385 micrometers) from the star MWC349A. This object has strong hydrogen maser emission (reported in the millimeter and submillimeter hydrogen recombination lines from H36(alpha) to H21(alpha)) and laser emission (reported in the H15(alpha), H12(alpha) and H10(alpha) lines). The lasers/masers are thought to arise predominantly in a Keplerian disk around the star. The mid-IR lines do not show evident signs of lasing, and can be well modeled as arising from the strong stellar wind, with a component arising from a quasi-static atmosphere around the disk, similar to what is hypothesized for the near IR (less than or equal to 4 micrometers) recombination lines. Since populations inversions in the levels producing these mid-IR transitions are expected at densities up to approximately 10(exp 11)/cu cm, these results imply either that the disk does not contain high-density ionized gas over long enough path lengths to produce a gain approximately 1, and/or that any laser emission from such regions is small compared to the spontaneous background emission from the rest of the source as observed with a large beam. The results reinforce the interpretation of the far-IR lines as true lasers.

  14. On the Thermal Line Emission from the Outflows in Ultraluminous X-Ray Sources

    NASA Astrophysics Data System (ADS)

    Xu, Ya-Di; Cao, Xinwu

    2016-08-01

    The atomic features in the X-ray spectra of ultraluminous X-ray sources (ULXs) may be associated with the outflow, which may provide a way to explore the physics of the ULXs. We construct a conical outflow model and calculate the thermal X-ray Fe emission lines from the outflows. Our results show that thermal line luminosity decreases with increasing outflow velocity and/or opening angle of the outflow for a fixed kinetic power of the outflows. Assuming the kinetic power of the outflows to be comparable with the accretion power in the ULXs, we find that the equivalent width can be several eV for the thermal X-ray Fe emission line from the outflows in the ULXs with stellar-mass black holes. The thermal line luminosity is proportional to 1/M bh (M bh is the black hole mass of the ULX). The equivalent width decreases with the black hole mass, which implies that the Fe line emission from the outflows can hardly be detected if the ULXs contain intermediate-mass black holes. Our results suggest that the thermal X-ray Fe line emission should be preferentially be detected in the ULXs with high kinetic power slowly moving outflows from the accretion disks surrounding stellar-mass black holes/neutron stars. The recently observed X-ray atomic features of the outflows in a ULX may imply that it contains a stellar-mass black hole.

  15. VizieR Online Data Catalog: Proxima Cen chromospheric emission lines (Fuhrmeister+, 2011)

    NASA Astrophysics Data System (ADS)

    Fuhrmeister, B.; Lalitha, S.; Poppenhaeger, K.; Rudolf, N.; Liefke, C.; Reiners, A.; Schmitt, J. H. M. M.; Ness, J.-U.

    2011-08-01

    We present an extensive identification catalog of chromospheric emission lines in the optical range for a flare on Proxima Centauri. The data were obtained with ESO's Kueyen telescope equipped with the UVES spectrograph on March 9/10, 11/12, 13/14 in 2009. The instrument was operated in dichroic mode (spectral coverage from 3290 to 4500 and from 6400 to 10080Å). We tabulate measured wavelength, line flux and FWHM for every line and also provide the rest wavelength from the Moore catalog which was used for identification (Moore, 1972, Nat. Stand. Ref. Data. Ser., 40). Few lines were identified with the NIST database. (1 data file).

  16. Three steps to the CIELO: VO and high-resolution spectroscopy chase the origin of soft X-rays in obscured AGN

    NASA Astrophysics Data System (ADS)

    Guainazzi, M.; Bianchi, S.

    The origin of the soft X-ray emission in obscured Active Galactic Nuclei AGN is still largely unknown despite important progress made possible by recent measurements with Chandra and XMM-Newton Our understanding of the evolution of accretion onto supermassive black holes and of its interaction with gas and stars in the dense nuclear environment would receive a dramatic burst by the solution of this mystery In this paper we will a show why high-resolution X-ray spectroscopy is crucial to the solution of this issue b present CIELO the first catalogue of soft X-ray emission lines in obscured AGN 80 sources built from observations of the Reflection Grating Spectrometer RGS on-board XMM-Newton c discuss the implementation of the IVOA Line Data Model in VO tools such as the SED builder VOSpec and its application to CIELO The combination of the unprecedented RGS sensitivity in the soft X-ray regime and of the VO protocols power leads us to be closer than ever to unveiling the nature of soft X-ray emission in obscured AGN

  17. Physics of Gamma Ray Emitting AGN

    NASA Astrophysics Data System (ADS)

    Ojha, Roopesh; Lovell, Jim; Edwards, Philip; Kadler, Matthias; Monitoringteam, Gamma Ray Blazar

    2012-10-01

    The TANAMI VLBI monitoring program, which was granted Large Proposal status from Oct 2009, was set up to capitalize on a 5-10 year window of opportunity provided by the Fermi gamma-ray telescope. TANAMI and its associated components at other wavebands perform simultaneous observations of AGN across the electromagnetic spectrum. Such observations are key to addressing fundamental questions of AGN physics. TANAMI is the only dual-frequency VLBI monitoring program covering the southern third of the sky while Fermi is observing. As such, it is indispensable for tracking parsec-scale jet components and associating their behaviour with changes at high energies. Jet parameters such as speeds and Doppler factors, that are essential inputs to understanding AGN physics, can only be measured with VLBI observations over many years. We request continuation of TANAMI so that the baseline of unique information on kinematics, morphology and the correlation of changes in both with emission at other wavebands, that we have set up can continue to provide important results and indeed produce its highest impact science as we reach critical number of epochs of data on an increasing fraction of our sample.

  18. 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

  19. The Sloan Digital Sky Survey Reverberation Mapping Project: Velocity Shifts of Quasar Emission Lines

    NASA Astrophysics Data System (ADS)

    Shen, Yue; Brandt, W. N.; Richards, Gordon T.; Denney, Kelly D.; Greene, Jenny E.; Grier, C. J.; Ho, Luis C.; Peterson, Bradley M.; Petitjean, Patrick; Schneider, Donald P.; Tao, Charling; Trump, Jonathan R.

    2016-11-01

    Quasar emission lines are often shifted from the systemic velocity due to various dynamical and radiative processes in the line-emitting region. The level of these velocity shifts depends both on the line species and on quasar properties. We study velocity shifts for the line peaks (not the centroids) of various narrow and broad quasar emission lines relative to systemic using a sample of 849 quasars from the Sloan Digital Sky Survey Reverberation Mapping (SDSS-RM) project. The coadded (from 32 epochs) spectra of individual quasars have sufficient signal-to-noise ratio (S/N) to measure stellar absorption lines to provide reliable systemic velocity estimates, as well as weak narrow emission lines. The large dynamic range in quasar luminosity (∼2 dex) of the sample allowed us to explore potential luminosity dependence of the velocity shifts. We derive average line peak velocity shifts as a function of quasar luminosity for different lines, and quantify their intrinsic scatter. We further quantify how well the peak velocity can be measured as a function of continuum S/N, and demonstrate that there is no systematic bias in the velocity measurements when S/N is degraded to as low as ∼3 per SDSS pixel (∼ 69 {km} {{{s}}}-1). Based on the observed line shifts, we provide empirical guidelines on redshift estimation from [O ii] λ 3727, [O iii] λ 5007, [Ne v] λ 3426, Mg ii, C iii], He ii λ 1640, broad Hβ, C iv, and Si iv, which are calibrated to provide unbiased systemic redshifts in the mean, but with increasing intrinsic uncertainties of 46, 56, 119, 205, 233, 242, 400, 415, and 477 {km} {{{s}}}-1, in addition to the measurement uncertainties. These results demonstrate the infeasibility of measuring quasar redshifts to better than ∼ 200 {km} {{{s}}}-1 with only broad lines.

  20. 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.

  1. An optical emission-line phase of the extreme carbon star IRC +30219

    NASA Technical Reports Server (NTRS)

    Cohen, M.

    1980-01-01

    Optical spectroscopic monitoring of the extreme carbon star IRC +30219 has revealed striking changes between 1977 and 1980. The stellar photosphere was barely visible in early 1979. There was an emission line spectrum consisting of H, forbidden O I, forbidden O II, forbidden N I, forbidden N II, forbidden S II, and He I. It is likely that these lines arose in a shocked region where recent stellar mass loss encountered the extensive circumstellar envelope. By late 1979, this emission-line spectrum had vanished, and the photosphere had reappeared. The weakening of the photospheric features in early 1979 was caused by increased attenuation of starlight and overlying thermal emission, both due to recently condensed hot dust grains.

  2. Possible detection of far-ultraviolet line emission from a hot galactic corona

    NASA Technical Reports Server (NTRS)

    Feldman, P. D.; Brune, W. H.; Henry, R. C.

    1981-01-01

    The presence of an emission-line component to the radiation field is suggested by rocket observations, at low resolution, of the spectrum of the diffuse, far-ultraviolet background near the north galactic pole. Removal of the line emission leaves a residual uniform cosmic ultraviolet background radiation of only 150 + or - 50 photons/sq cm s sr A, or about half that previously reported. The lines, which are at the wavelengths of the collisionally-excited atom emissions that have been predicted to arise from a hot galactic corona, suggest that there is no need to explain observed high-ionization states at high galactic latitudes as being due to photoionization caused by neutrino decay.

  3. The asymmetric profile of the H76 alpha line emission from MWC349

    NASA Technical Reports Server (NTRS)

    Rodriquez, L. F.; Canto, J.; Escalante, V.; Moran, J. M.

    1986-01-01

    MWC349 is an emission-line star found by Merrill, Humason and Burwell (1932). Braes, Habing and Schoenmaker (1972) discovered that it is a strong radio source. The radio emission originates in a massive ionized wind that is expanding with a velocity of about 50 km s(-1). Its continuum spectrum fits well a nu(0.6) power law from the cm wavelengths to the far-IR. Radio recombination line emission from the envelope of MWC349 was first detected by Altenhoff, Strittmatter and Wendker (1981). We have obtained good signal-to-noise ratio, Very Large Array observations of the H76 alpha radio recombination line from the ionized wind of MWC349. Our data reveal that the profile is markedly asymmetric, with a steep rise on the blue side. This asymmetry could be due to non-LTE effects in the formation and transfer of the line or to intrinsic asymmetries in the envelope. Our analysis suggests that most probably the peculiar profile is caused by a non-LTE enhancement of the line emission from the side of the envelope nearer to the observer. This asymmetry has the opposite sense than that observed in optical and IR recombination lines, where a different effect (absorption of the stellar continuum by the gas in the wind between the star and the observer) is known to be dominant, leading to the classic P Cygni profile. We propose that the profiles of the radio recombination lines from ionized stellar winds will have this characteristic shape, while optical and IR recombination lines are characterized by P Cygni-like profiles. Unfortunately, at present the detection of radio recombination lines from ionized stellar winds is only feasible for MWC349 and a few other objects.

  4. HST WFC3 Early Release Science: Emission-line Galaxies from IR Grism Observations

    NASA Astrophysics Data System (ADS)

    Straughn, Amber; Kuntschner, H.; Kuemmel, M.; Walsh, J.; Cohen, S.; Gardner, J. P.; Windhorst, R. A.; O'Connell, R. W.; Pirzkal, N.; Meurer, G.; McCarthy, P. J.; Hathi, N. P.; Malhotra, S.; Rhoads, J.; SOC, WFC3

    2011-01-01

    The Early Release Science II program for HST WFC3 includes one pointing observed with the G102 (0.8-1.1 microns; R 210) and G141 (1.1-1.6 microns; R 130) infrared grisms at a depth of 2 orbits/grism. From this data we detect 48 actively star-forming emission-line galaxies and measure the galaxies' redshifts, line fluxes, star-formation rates, and masses. In particular, the prominent emission lines Ha, [OII], and [OIII] fall into the two infrared grism bandpasses over a redshift range z=0.2-3.6, and the majority of galaxies have at least two lines in the observable wavelength range resulting in secure line identification and redshift determination. We detect galaxies with line fluxes to 3 x 10-17 erg/s/cm2 as well as several sources with very high EW lines. The higher spectral resolution and sensitivity of the WFC3 grisms over previous instrumentation also allows detection of other emission lines in some galaxies. The average magnitude of the emission-line galaxy sample is mAB(F098M)=23.6 mag with more than 20% of the sample fainter than mAB(F098M)=25 mag, demonstrating the remarkable efficiency and capability of the WFC3 NIR grisms for measuring galaxy properties to faint magnitudes and intermediate redshifts. Our results point to the promising potential for future science with WFC3 grism spectroscopy, as well as upcoming missions such as JWST and WFIRST. This paper is based on Early Release Science observations made by the WFC3 Scientific Oversight Committee. We are grateful to the Director of the Space Telescope Science Institute for awarding Director's Discretionary time for this program. This research was supported in part by an appointment to the NASA Postdoctoral Program at Goddard Space Flight Center, administered by Oak Ridge Associated Universities through a contract with NASA (ANS).

  5. Is there an Obscured AGN in the Normal Galaxy IRASF01063-8034

    NASA Technical Reports Server (NTRS)

    Greenhill, Lincoln J.

    2004-01-01

    The target galactic nucleus is ostensibly "normal," but the presence of water maser emission indicates that it may be an obscured AGN. Our primary goal has been to test this hypothesis through the detection hard X-ray emission and an X-ray spectrum characteristic of heavy absorption. The data for this program became available in May 2003. Light curves show that most of the data are good and that the background was well behaved. We have constructed images and found the X-ray emission in this target is a hard and may be extended. The presence of an AGN has been confirmed through observation with XMM. This is one of many edge-on normal galaxies that may contain AGN. The orientation of the extension will be compared to the structure of molecular gas observed at high angular resolution with VLBI. These radio observations were completed in August 2003. Correlation was completed in late 2003. The data have yet to be delivered by the ATNF. Since the start of the program, we have also obtained six radio spectra, on top of the two obtained at or close to the epoch of discovery for the maser. Early indications were that the maser emission exhibited unusually broad velocity extent and that it "jumped in velocity on time scales of weeks. This behavior has been speculated to be the signature of emission excited by jet-ISM interactions. After more extensive and more sensitive radio study, we find that (1) the emission does not in fact change velocity centroid substantially and (2) it comprises narrower, more "normal" emission features. The joint interpretation of radio and XMM data will be possible once the VLBI images and position-resolved X-ray spectra have been made, probably in summer 2004. If the radio emission arises in an accretion disk, rather than a jet, then we may predict that the VLBI images will exhibit velocity-position gradients orthogonal to the extension of X-ray emission, which presumably traces an optical narrow line or outflow region.

  6. 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.

  7. Composition of an emission line system in black hole host globular cluster RZ2109

    SciTech Connect

    Steele, Matthew M.; Zepf, Stephen E.; Maccarone, Thomas J.; Kundu, Arunav; Rhode, Katherine L.; Salzer, John J.

    2014-04-20

    We present an analysis of optical spectra from the globular cluster RZ2109 in NGC 4472, which hosts the first unambiguous globular cluster black hole. We use these spectra to determine the elemental composition of the emission line system associated with this source, and to constrain the age and metallicity of the host globular cluster. For the emission line system of RZ2109, our analysis indicates the [O III] λ5007 equivalent width is 33.82 ± 0.39 Å and the Hβ equivalent width is 0.32 ± 0.32 Å, producing a formal [O III] λ5007/Hβ emission line ratio of 106 for a 3200 km s{sup –1} measurement aperture covering the full velocity width of the [O III] λ5007 line. Within a narrower 600 km s{sup –1} aperture covering the highest luminosity velocity structure in the line complex, we find [O III] λ5007/Hβ = 62. The measured [O III] λ5007/Hβ ratios are significantly higher than can be produced in radiative models of the emission line region with solar composition, and the confidence interval limits exclude all but models which have gas masses much larger than those for a single star. Therefore, we conclude that the region from which the [O III] λ5007 emission originates is hydrogen-depleted relative to solar composition gas. This finding is consistent with emission from an accretion-powered outflow driven by a hydrogen-depleted donor star, such as a white dwarf, being accreted onto a black hole.

  8. (12)CO (3-2) & (1-0) emission line observations of nearby starburst galaxy nuclei

    NASA Technical Reports Server (NTRS)

    Devereux, Nicholas; Taniguchi, Yoshiaki; Sanders, D. B.; Nakai, N.; Young, J. S.

    1994-01-01

    New measurements of the (12)CO (1-0) and (12)CO (3-2) line emission are presented for the nuclei of seven nearby starburst galaxies selected from a complete sample of 21 nearby starburst galaxies for which the nuclear star formation rates are measured to be comparable to the archetype starburst galaxies M82 and NGC 253. The new observations capitalize on the coincidence between the beam size of the 45 m Nobeyama telescope at 115 GHz and that of the 15 m James Clerk Maxwell Telescope at 345 GHz to measure the value of the (12)CO (3-2)/(1-0) emission line ratio in a 15 sec (less than or equal to 2.5 kpc) diameter region centered on the nuclear starburst. In principle, the (12)CO (3-2)/(1-0) emission line ratio provides a measure of temperature and optical depth for the (12)CO gas. The error weighted mean value of the (12)CO (3-2)/(1-0) emission line ratio measured for the seven starburst galaxy nuclei is -0.64 +/- 0.06. The (12)CO (3-2)/(1-0) emission line ratio measured for the starburst galaxy nuclei is significantly higher than the average value measured for molecular gas in the disk of the Galaxy, implying warmer temperatures for the molecular gas in starburst galaxy nuclei. On the other hand, the (12)CO (3-2)/(1-0) emission line ratio measured for the starburst galaxy nuclei is not as high as would be expected if the molecular gas were hot, greater than 20 K, and optically thin, tau much less than 1. The total mass of molecular gas contained within the central 1.2-2.8 kpc diameter region of the starburst galaxy nuclei ranges from 10(exp 8) to 10(exp 9) solar mass. While substantial, the molecular gas mass represents only a small percentage, approximately 9%-16%, of the dynamical mass in the same region.

  9. Large-scale outflows in luminous QSOs revisited. The impact of beam smearing on AGN feedback efficiencies

    NASA Astrophysics Data System (ADS)

    Husemann, B.; Scharwächter, J.; Bennert, V. N.; Mainieri, V.; Woo, J.-H.; Kakkad, D.

    2016-10-01

    Context. Feedback from active galactic nuclei (AGN) is thought to play an important role in quenching star formation in galaxies. However, the efficiency with which AGN dissipate their radiative energy into the ambient medium remains strongly debated. Aims: Enormous observational efforts have been made to constrain the energetics of AGN feedback by mapping the kinematics of the ionized gas on kpc scale. We study how the observed kinematics and inferred energetics are affected by beam smearing of a bright unresolved narrow-line region (NLR) due to seeing. Methods: We re-analyse optical integral-field spectroscopy of a sample of twelve luminous unobscured quasi-stellar objects (QSOs) (0.4 line component. Therefore, we are able to compare the ionized gas kinematics and derived energetics of the total, truly spatially extended, and unresolved [O iii] emission. Results: We find that the spatially resolved [O iii] line width on kpc scales is significantly narrower than the one before PSF deblending. The extended NLRs (ENLRs) appear intrinsically offset from the QSO position or more elongated which can be interpreted in favour of a conical outflow on large scales while a spherical geometry cannot be ruled out for the unresolved NLR. We find that the kinetic power at 5 kpc distance based on a spherical model is reduced by two orders of magnitude for a conical outflow and one order of magnitude for the unresolved NLR after PSF deblending. This reduced kinetic power corresponds to only 0.01-0.1 per cent of the bolometric AGN luminosity. This is