Searches for H2O masers toward narrow-line Seyfert 1 galaxies

NASA Astrophysics Data System (ADS)

Yoshiaki, Hagiwara; Doi, Akihiro; Hachisuka, Kazuya; Horiuchi, Shinji

2018-05-01

We present searches for 22 GHz H2O masers toward 36 narrow-line Seyfert 1 galaxies (NLS1s), selected from known NLS1s with vsys ≲ 41000 km s-1. Out of the 36 NLS1s in our sample, 11 have been first surveyed in our observations, while the observations of other NLS1s were previously reported in literature. In our survey, no new water maser source from NLS1s was detected at the 3σ rms level of 8.4 mJy to 144 mJy, which depends on different observing conditions or inhomogeneous sensitivities of each observation using three different telescopes. It is likely that the non-detection of new masers in our NLS1 sample is primarily due to insufficient sensitivities of our observations. Including the five known NLS1 masers, the total detection rate of the H2O maser in NLS1s is not remarkably different from that of type 2 Seyfert galaxies or LINERs. However, more extensive and systematic searches of NLS1 would be required for a statistical discussion of the detection rate of the NLS1 maser, compared with that of type 2 Seyferts or LINERs.

Searches for H2O masers toward narrow-line Seyfert 1 galaxies

NASA Astrophysics Data System (ADS)

Hagiwara, Yoshiaki; Doi, Akihiro; Hachisuka, Kazuya; Horiuchi, Shinji

2018-06-01

We present searches for 22 GHz H2O masers toward 36 narrow-line Seyfert 1 galaxies (NLS1s), selected from known NLS1s with vsys ≲ 41000 km s-1. Out of the 36 NLS1s in our sample, 11 have been first surveyed in our observations, while the observations of other NLS1s were previously reported in literature. In our survey, no new water maser source from NLS1s was detected at the 3σ rms level of 8.4 mJy to 144 mJy, which depends on different observing conditions or inhomogeneous sensitivities of each observation using three different telescopes. It is likely that the non-detection of new masers in our NLS1 sample is primarily due to insufficient sensitivities of our observations. Including the five known NLS1 masers, the total detection rate of the H2O maser in NLS1s is not remarkably different from that of type 2 Seyfert galaxies or LINERs. However, more extensive and systematic searches of NLS1 would be required for a statistical discussion of the detection rate of the NLS1 maser, compared with that of type 2 Seyferts or LINERs.

THE CLUSTERING CHARACTERISTICS OF H I-SELECTED GALAXIES FROM THE 40% ALFALFA SURVEY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martin, Ann M.; Giovanelli, Riccardo; Haynes, Martha P.

The 40% Arecibo Legacy Fast ALFA survey catalog ({alpha}.40) of {approx}10,150 H I-selected galaxies is used to analyze the clustering properties of gas-rich galaxies. By employing the Landy-Szalay estimator and a full covariance analysis for the two-point galaxy-galaxy correlation function, we obtain the real-space correlation function and model it as a power law, {xi}(r) = (r/r{sub 0}){sup -{gamma}}, on scales <10 h{sup -1} Mpc. As the largest sample of blindly H I-selected galaxies to date, {alpha}.40 provides detailed understanding of the clustering of this population. We find {gamma} = 1.51 {+-} 0.09 and r{sub 0} = 3.3 + 0.3, -0.2more » h{sup -1} Mpc, reinforcing the understanding that gas-rich galaxies represent the most weakly clustered galaxy population known; we also observe a departure from a pure power-law shape at intermediate scales, as predicted in {Lambda}CDM halo occupation distribution models. Furthermore, we measure the bias parameter for the {alpha}.40 galaxy sample and find that H I galaxies are severely antibiased on small scales, but only weakly antibiased on large scales. The robust measurement of the correlation function for gas-rich galaxies obtained via the {alpha}.40 sample constrains models of the distribution of H I in simulated galaxies, and will be employed to better understand the role of gas in environmentally dependent galaxy evolution.« less

CO in Hickson compact group galaxies with enhanced warm H2 emission: Evidence for galaxy evolution?

NASA Astrophysics Data System (ADS)

Lisenfeld, U.; Appleton, P. N.; Cluver, M. E.; Guillard, P.; Alatalo, K.; Ogle, P.

2014-10-01

Context. Galaxies in Hickson Compact Groups (HCGs) are believed to experience morphological transformations from blue, star-forming galaxies to red, early-type galaxies. Galaxies with a high ratio between the luminosities of the warm H2 to the 7.7 μm PAH emission (so-called Molecular Hydrogen Emission Galaxies, MOHEGs) are predominantly in an intermediate phase, the green valley. Their enhanced H2 emission suggests that the molecular gas is affected in the transition. Aims: We study the properties of the molecular gas traced by CO in galaxies in HCGs with measured warm H2 emission in order to look for evidence of the perturbations affecting the warm H2 in the kinematics, morphology and mass of the molecular gas. Methods: We observed the CO(1-0) emission of 20 galaxies in HCGs and complemented our sample with 11 CO(1-0) spectra from the literature. Most of the galaxies have measured warm H2 emission, and 14 of them are classified as MOHEGs. We mapped some of these galaxies in order to search for extra-galactic CO emission. We analyzed the molecular gas mass derived from CO(1-0), MH2, and its kinematics, and then compared it to the mass of the warm molecular gas, the stellar mass and star formation rate (SFR). Results: Our results are the following. (i) The mass ratio between the CO-derived and the warm H2 molecular gas is in the same range as found for field galaxies. (ii) Some of the galaxies, mostly MOHEGs, have very broad CO linewidths of up to 1000 km s-1 in the central pointing. The line shapes are irregular and show various components. (iii) In the mapped objects we found asymmetric distributions of the cold molecular gas. (iv) The star formation efficiency (=SFR/MH2) of galaxies in HCGs is very similar to isolated galaxies. No significant difference between MOHEGs and non-MOHEGs or between early-type and spiral galaxies has been found. In a few objects the SFE is significantly lower, indicating the presence of molecular gas that is not actively forming stars

H I absorption in nearby compact radio galaxies

NASA Astrophysics Data System (ADS)

Glowacki, M.; Allison, J. R.; Sadler, E. M.; Moss, V. A.; Curran, S. J.; Musaeva, A.; Deng, C.; Parry, R.; Sligo, M. C.

2017-05-01

H I absorption studies yield information on both active galactic nucleus (AGN) feeding and feedback processes. This AGN activity interacts with the neutral gas in compact radio sources, which are believed to represent the young or recently re-triggered AGN population. We present the results of a survey for H I absorption in a sample of 66 compact radio sources at 0.040 < z < 0.096 with the Australia Telescope Compact Array. In total, we obtained seven detections, five of which are new, with a large range of peak optical depths (3-87 per cent). Of the detections, 71 per cent exhibit asymmetric, broad (ΔvFWHM > 100 km s-1) features, indicative of disturbed gas kinematics. Such broad, shallow and offset features are also found within low-excitation radio galaxies which is attributed to disturbed circumnuclear gas, consistent with early-type galaxies typically devoid of a gas-rich disc. Comparing mid-infrared colours of our galaxies with H I detections indicates that narrow and deep absorption features are preferentially found in late-type and high-excitation radio galaxies in our sample. These features are attributed to gas in galactic discs. By combining XMM-Newton archival data with 21-cm data, we find support that absorbed X-ray sources may be good tracers of H I content within the host galaxy. This sample extends previous H I surveys in compact radio galaxies to lower radio luminosities and provides a basis for future work exploring the higher redshift universe.

An H I study of the collisional ring galaxy NGC 922

NASA Astrophysics Data System (ADS)

Elagali, Ahmed; Wong, O. Ivy; Oh, Se-Heon; Staveley-Smith, Lister; Koribalski, Bärbel S.; Bekki, Kenji; Zwaan, Martin

2018-06-01

We present new atomic hydrogen (H I) observations of the collisional ring galaxy NGC 922 obtained using the Australia Telescope Compact Array. Our observations reveal for the first time the vast extent of the H I disc of this galaxy. The H I morphology and kinematics of NGC 922 show that this galaxy is not the product of a simple drop-through interaction, but has a more complex interaction history. The integrated H I flux density of NGC 922 from our observations is 24.7 Jy km s-1, which is within the error of the flux value obtained using the 64-m Parkes radio telescope. This flux density translates to a total H I mass of 1.1 × 1010 M⊙ and corresponds to an H I to total mass fraction (M_{H I}}/Mtot) of approximately 0.11. The gaseous structures of NGC 922 are more extended to the north and include an H I tail that has a projected physical length of 8 kpc. Gas warps are also evident in the velocity field of NGC 922 and are more prominent on the approaching and the western side of the disc. In comparison with a large sample of star-forming galaxies in the local Universe, NGC 922 possesses a high gas fraction relative to galaxies with a similar stellar mass of ˜1010.4 M⊙, and exhibits a high specific star formation rate.

(Almost) Dark Galaxies in the ALFALFA Survey: Isolated H I-bearing Ultra-diffuse Galaxies

NASA Astrophysics Data System (ADS)

Leisman, Lukas; Haynes, Martha P.; Janowiecki, Steven; Hallenbeck, Gregory; Józsa, Gyula; Giovanelli, Riccardo; Adams, Elizabeth A. K.; Bernal Neira, David; Cannon, John M.; Janesh, William F.; Rhode, Katherine L.; Salzer, John J.

2017-06-01

We present a sample of 115 very low optical surface brightness, highly extended, H I-rich galaxies carefully selected from the ALFALFA survey that have similar optical absolute magnitudes, surface brightnesses, and radii to recently discovered “ultra-diffuse” galaxies (UDGs). However, these systems are bluer and have more irregular morphologies than other UDGs, are isolated, and contain significant reservoirs of H I. We find that while these sources have normal star formation rates for H I-selected galaxies of similar stellar mass, they have very low star formation efficiencies. We further present deep optical and H I-synthesis follow-up imaging of three of these H I-bearing ultra-diffuse sources. We measure H I diameters extending to ˜40 kpc, but note that while all three sources have large H I diameters for their stellar mass, they are consistent with the H I mass-H I radius relation. We further analyze the H I velocity widths and rotation velocities for the unresolved and resolved sources, respectively, and find that the sources appear to inhabit halos of dwarf galaxies. We estimate spin parameters, and suggest that these sources may exist in high spin parameter halos, and as such may be potential H I-rich progenitors to the ultra-diffuse galaxies observed in cluster environments.

49 CFR 577.2 - Purpose.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 7 2011-10-01 2011-10-01 false Purpose. 577.2 Section 577.2 Transportation Other... OF TRANSPORTATION (CONTINUED) DEFECT AND NONCOMPLIANCE NOTIFICATION § 577.2 Purpose. The purpose of... equipment are made aware of the existence of defects and noncompliances and of their rights and...

49 CFR 577.2 - Purpose.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 7 2010-10-01 2010-10-01 false Purpose. 577.2 Section 577.2 Transportation Other... OF TRANSPORTATION (CONTINUED) DEFECT AND NONCOMPLIANCE NOTIFICATION § 577.2 Purpose. The purpose of... equipment are made aware of the existence of defects and noncompliances and of their rights and...

The H I content of non-isolated galaxies

NASA Technical Reports Server (NTRS)

Zasov, Anatoli V.

1990-01-01

It seems obvious that the evolution of star formation rate and hence of gas content in galaxies strongly depends on their environment. It reveals itself in particular in enhanced star formation or even in a strong burst of activity of massive stars often observed in interacting galaxies. Nevertheless it should be noted that the time scale for the gas to be exhausted in these galaxies is unknown even approximately. To clarify a role of surroundings in the evolution of disk galaxies we should compare the H I content of isolated and non-isolated galaxies otherwise similar by their properties. It is concluded that there are no systematic differences between H I content in isolated and non-isolated late-type galaxies; in spite of the differences of star formation rates their hydrogen mass is determined by slowly evolving kinematic parameters of the disk. Enhanced star formation in interacting galaxies, if it lasts long enough, must have an initial mass function enriched in massive stars in order not to significantly reduce the supply of gas. Certainly these conclusions are not valid for galaxies which are members of rich clusters such as Virgo or Coma, where H I-deficiency really exists, possibly due to the interaction of interstellar H I with hot intergalactic gas.

Detection of H I absorption in the dwarf galaxy Haro 11

NASA Astrophysics Data System (ADS)

MacHattie, Jeremy A.; Irwin, Judith A.; Madden, Suzanne C.; Cormier, Diane; Rémy-Ruyer, Aurélie

2014-02-01

We present the results of an analysis of archival 21 cm (H I) data of the blue compact dwarf galaxy Haro 11 (ESO 350-IG038). Observations were obtained at the Very Large Array, and the presence of a compact absorption feature near the optical centre of the galaxy has been detected. The central location of the absorption feature coincides with the centre of the continuum background of the galaxy, as well as with the location of knot B. The absorption feature yields an H I mass in the range of 3-10 × 108 M⊙, corresponding to spin temperatures from 91 K to 200 K, respectively. The absence of H I seen in emission places an upper limit of 1.7 × 109 M⊙ on the mass. To our knowledge this is the first example of a dwarf galaxy that shows H I absorption from its own background continuum. The continuum emission from the galaxy is also used to determine star formation rates, namely 6.85 ± 0.05 M⊙ yr-1 (for a stellar mass range of 5 M⊙ < M < 100 M⊙), or 32.8 ± 0.2 M⊙ yr-1 (for an extended range of 0.1 M⊙ < M < 100 M⊙).

25 CFR 577.12 - Intervention.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 25 Indians 2 2012-04-01 2012-04-01 false Intervention. 577.12 Section 577.12 Indians NATIONAL... THE COMMISSION § 577.12 Intervention. (a) Persons other than the respondent may be permitted to...) Intervention would not unfairly prejudice existing parties or delay resolution of the proceeding. (b) If a...

25 CFR 577.12 - Intervention.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 25 Indians 2 2011-04-01 2011-04-01 false Intervention. 577.12 Section 577.12 Indians NATIONAL... THE COMMISSION § 577.12 Intervention. (a) Persons other than the respondent may be permitted to...) Intervention would not unfairly prejudice existing parties or delay resolution of the proceeding. (b) If a...

25 CFR 577.12 - Intervention.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 25 Indians 2 2010-04-01 2010-04-01 false Intervention. 577.12 Section 577.12 Indians NATIONAL... THE COMMISSION § 577.12 Intervention. (a) Persons other than the respondent may be permitted to...) Intervention would not unfairly prejudice existing parties or delay resolution of the proceeding. (b) If a...

H II regions in the dwarf galaxy UGC-A 86

NASA Technical Reports Server (NTRS)

Miller, Bryan W.; Hodge, Paul

1993-01-01

The uncertain nature of the dwarf irregular galaxy UGC-A 86 (VIIZw009) makes it a very interesting object for studying star formation at the low end of the galaxy luminosity function. Saha and Hoessel (1991) find that this object is composed of two main parts, one of which appears more resolved than the other. The more resolved component has an excess of blue stars, suggesting that it is currently undergoing star formation. Thus, they argue that UGC-A 86 could be either a superposition of unrelated galaxies, two interacting galaxies, or a single galaxy. However, surface photometry performed by Richter et al. (1991) indicates that it is a single galaxy with an exponential luminosity profile. Richter et al. also find UGC-A 86 to be extremely dusty and to be associated with the infrared source IRAS 3550+6657. The uncertainty is compounded by the large ambiguity in the distance, though a heliocentric H1 velocity of 80 plus or minus 7 km s(sup -1) suggests that it is either a member of the Local Group or perhaps the IC 342 group. A distance of 1.5 Mpc and a reddening of E(B - V) = 0.65 is adopted. UGC-A 86 in H-alpha was observed in order to measure its current star formation rate. This is part of a larger project to study the star formation rates and histories of a complete sample of dwarf galaxies in the Local Group and other nearby groups. The H region luminosity function and size distribution for UGC-A 86 are presented and compared with previous observations of similar dwarf galaxies.

The Peculiar Radio-loud Narrow Line Seyfert 1 Galaxy 1H 0323+342

NASA Astrophysics Data System (ADS)

Paliya, Vaidehi S.; Sahayanathan, S.; Parker, M. L.; Fabian, A. C.; Stalin, C. S.; Anjum, Ayesha; Pandey, S. B.

2014-07-01

We present a multiwavelength study of the radio-loud narrow-line Seyfert 1 galaxy (NLSy1) 1H 0323+342, detected by the Fermi Gamma-Ray Space Telescope. Multiband light curves show many orphan X-ray and optical flares having no corresponding γ-ray counterparts. Such anomalous variability behavior can be due to different locations of the emission region from the central source. During a large flare, a γ-ray flux doubling timescale as small as ~3 hr is noticed. We built spectral energy distributions (SEDs) during different activity states and modeled them using a one-zone leptonic model. The shape of the optical/UV component of the SEDs is dominated by accretion disk emission in all the activity states. In the X-ray band, significant thermal emission from the hot corona is inferred during quiescent and first flaring states; however, during subsequent flares, the nonthermal jet component dominates. The γ-ray emission in all the states can be well explained by inverse-Compton scattering of accretion disk photons reprocessed by the broad-line region. The source showed violent intra-night optical variability, coinciding with one of the high γ-ray activity states. An analysis of the overall X-ray spectrum fitted with an absorbed power-law plus relativistic reflection component hints at the presence of an Fe Kα line and returns a high black hole spin value of a = 0.96 ± 0.14. We argue that 1H 0323+342 possesses dual characteristics, akin to both flat-spectrum radio quasars (FSRQs) and radio-quiet NLSy1 galaxies, though at a low jet power regime compared to powerful FSRQs.

(Almost) Dark Galaxies in the ALFALFA Survey: Isolated H i-bearing Ultra-diffuse Galaxies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leisman, Lukas; Haynes, Martha P.; Giovanelli, Riccardo

2017-06-20

We present a sample of 115 very low optical surface brightness, highly extended, H i-rich galaxies carefully selected from the ALFALFA survey that have similar optical absolute magnitudes, surface brightnesses, and radii to recently discovered “ultra-diffuse” galaxies (UDGs). However, these systems are bluer and have more irregular morphologies than other UDGs, are isolated, and contain significant reservoirs of H i. We find that while these sources have normal star formation rates for H i-selected galaxies of similar stellar mass, they have very low star formation efficiencies. We further present deep optical and H i-synthesis follow-up imaging of three of thesemore » H i-bearing ultra-diffuse sources. We measure H i diameters extending to ∼40 kpc, but note that while all three sources have large H i diameters for their stellar mass, they are consistent with the H i mass–H i radius relation. We further analyze the H i velocity widths and rotation velocities for the unresolved and resolved sources, respectively, and find that the sources appear to inhabit halos of dwarf galaxies. We estimate spin parameters, and suggest that these sources may exist in high spin parameter halos, and as such may be potential H i-rich progenitors to the ultra-diffuse galaxies observed in cluster environments.« less

The discovery of five new H2O megamasers in active galaxies

NASA Technical Reports Server (NTRS)

Braatz, J. A.; Wilson, A. S.; Henkel, C.

1994-01-01

H2O megamasers with (isotropic) luminosities between 60 and 200 solar luminosity (H(sub 0) = 75 km/s/Mpc) have been detected in the Seyfert 2 galaxies Mrk 1, Mrk 1210, and NGC 5506 and in the LINERs NGC 1052 and NGC 2639. No megamasers have been found in Seyfert 1's. The galaxies have redshifts between 1500 and 4800 km/s and are the most distant H2O sources reported to date. NGC 1052 is also the first elliptical galaxy known to contain an H2O maser. The intensity distribution of an H2O five-point map obtained toward NGC 5506 shows that the H2O emission is pointlike compared to the 40 sec telescope beam. The lack of CO emission in NGC 1052 implies a conservative lower limit to the H2O brightness temperature of 1000 K, thus ruling out a thermal origin for the H2O emission. The success of this survey relative to other recent searches makes it evident that H2O megamasers are preferentially found in galaxies with active nuclei.

H-alpha Fabry-Perot interferometric observations of blue compact dwarf galaxies

NASA Technical Reports Server (NTRS)

Thuan, Trinh Xuan; Williams, T. B.; Malumuth, E.

1987-01-01

H-alpha Fabry-Perot interferometric observations of the two blue compact dwarf galaxies (BCDs) 7 Zw 403 and 1 Zw 49 are presented. The velocity field of 7 Zw 403 shows no clear large-scale organized motion but the velocity field is not completely chaotic either. The gas associated with the 8 H II regions in 7 Zw 403 has neither the highest nor lowest velocities. The BCD 1 Zw 49 is dominated by a single H II region which is about 50 times brighter than any other feature in the galaxy. There is a chain of fainter H II regions extending across the galaxy. The velocity field is well ordered along the H II region chain, but it is very complex around the dominant H II region, suggesting H-alpha loops and filaments around the latter. Both BCDs show velocity gradients of about 25 km/s on scales of about 10 pc in 7 Zw 403 and of about 50 pc in 1 Zw 49. These velocity discontinuities compress the gas and are probably responsible for the star formation.

A Combinatorial Geometry Computer Description of the M577A1 Light Tracked Command Post Carrier

DTIC Science & Technology

1979-12-01

REPORT DATE DECEMBER 1979 13. NUMBER OF PAGES 107 1 «. MONITORING AGENCY NAME ft ADDRESS(lf dlHermt Irom Controlling OUIce) 15...DISTRIBUTION LIST 103 LIST OF FIGURES Figure Page 1 . The M577A1 Command Post Carrier 10 2. Intersection (+), Subtraction (-), Union (OR) of Solids...with a computer- ized description of the M577A1. A photograph of the vehicle is shown in Figure 1 . Presently, the BRL employs a technique known as

GASS 3505: the prototype of H I-excess, passive galaxies

NASA Astrophysics Data System (ADS)

Geréb, K.; Catinella, B.; Cortese, L.; Bekki, K.; Moran, S. M.; Schiminovich, D.

2016-10-01

We present our multiwavelength analysis of a prototype H I-excess galaxy, GASS 3505, selected based on having a large gas content (M_{H I} = 10^{9.9} M⊙) compared to its little associated star formation activity (˜0.1 M⊙ yr-1) in the GALEX Arecibo SDSS Survey (GASS). Very Large Array observations show that the H I in GASS 3505 is distributed in a regularly rotating, extended (˜50 kpc radius) gas ring. In the SDSS optical image GASS 3505 appears as a bulge-dominated galaxy, however deep optical imaging reveals low surface brightness (≳25 mag arcsec-2) stellar emission around the central bulge. Direct evidence for accretion is detected in form of an extended (˜60 kpc) stellar stream, showing that GASS 3505 has experienced a minor merger in the recent past. We investigate the possibility that the H I ring in GASS 3505 was accreted in such a merger event using N-body and smoothed particle hydrodynamic simulations. The best model that reproduces the general properties (I.e. gas distribution and kinematics, stellar morphology) of the galaxy involves a merger between the central bulge and a gas-rich (M⋆ = 109 M⊙ and M_{H I}/M⋆ = 10) disc galaxy. However, small discrepancies in the observed and modelled properties could suggest that other sources of gas have to be involved in the build-up of the gas reservoir. This work is the first step towards a larger program to investigate the physical mechanisms that drive the large scatter in the gas scaling relations of nearby galaxies.

HIghMass—High H I Mass, H I-rich Galaxies at z ˜ 0: Combined H I and H2 Observations

NASA Astrophysics Data System (ADS)

Hallenbeck, Gregory; Huang, Shan; Spekkens, Kristine; Haynes, Martha P.; Giovanelli, Riccardo; Adams, Elizabeth A. K.; Brinchmann, Jarle; Carpenter, John; Chengalur, Jayaram; Hunt, Leslie K.; Masters, Karen L.; Saintonge, Amélie

2016-12-01

We present resolved {{H}} {{I}} and CO observations of three galaxies from the HIghMass sample, a sample of {{H}} {{I}}-massive ({M}{{H}{{I}}}\\gt {10}10 {M}⊙ ), gas-rich ({M}{{H}{{I}}} in the top 5% for their M *) galaxies identified in the ALFALFA survey. Despite their high gas fractions, these are not low-surface-brightness galaxies and have typical specific star formation rates (SFR/{M}* ) for their stellar masses. The three galaxies have normal SFRs for their {{{H}}}2 masses, but unusually short star formation efficiency scale lengths, indicating that the star formation bottleneck in these galaxies is in the conversion of {{H}} {{I}} to {{{H}}}2, not in converting {{{H}}}2 to stars. In addition, their dark matter spin parameters (λ) are above average, but not exceptionally high, suggesting that their star formation has been suppressed over cosmic time but is now becoming active, in agreement with prior Hα observations.

Extending the modeling of the anisotropic galaxy power spectrum to k = 0.4 hMpc-1

NASA Astrophysics Data System (ADS)

Hand, Nick; Seljak, Uroš; Beutler, Florian; Vlah, Zvonimir

2017-10-01

We present a model for the redshift-space power spectrum of galaxies and demonstrate its accuracy in describing the monopole, quadrupole, and hexadecapole of the galaxy density field down to scales of k = 0.4 hMpc-1. The model describes the clustering of galaxies in the context of a halo model and the clustering of the underlying halos in redshift space using a combination of Eulerian perturbation theory and N-body simulations. The modeling of redshift-space distortions is done using the so-called distribution function approach. The final model has 13 free parameters, and each parameter is physically motivated rather than a nuisance parameter, which allows the use of well-motivated priors. We account for the Finger-of-God effect from centrals and both isolated and non-isolated satellites rather than using a single velocity dispersion to describe the combined effect. We test and validate the accuracy of the model on several sets of high-fidelity N-body simulations, as well as realistic mock catalogs designed to simulate the BOSS DR12 CMASS data set. The suite of simulations covers a range of cosmologies and galaxy bias models, providing a rigorous test of the level of theoretical systematics present in the model. The level of bias in the recovered values of f σ8 is found to be small. When including scales to k = 0.4 hMpc-1, we find 15-30% gains in the statistical precision of f σ8 relative to k = 0.2 hMpc-1 and a roughly 10-15% improvement for the perpendicular Alcock-Paczynski parameter α⊥. Using the BOSS DR12 CMASS mocks as a benchmark for comparison, we estimate an uncertainty on f σ8 that is ~10-20% larger than other similar Fourier-space RSD models in the literature that use k <= 0.2 hMpc-1, suggesting that these models likely have a too-limited parametrization.

KPNO 0.9m H(alpha) Imaging Survey of ``Transforming Galaxies" in Local Galaxy Groups

NASA Astrophysics Data System (ADS)

Haines, Christopher; O'Sullivan, Ewan; Raychaudhury, Somak; Gargiulo, Adriana; Campusano, Luis

2012-02-01

We propose to use the KPNO 0.9-m telescope to obtain panoramic H(alpha) imaging of ~200 galaxies in two nearby (32, 35 Mpc) galaxy groups NGC 4261 and NGC 5353 from the CLoGS local group survey. In rich clusters ram-pressure stripping has been shown to be very effective at removing the gas contents and quenching star formation in infalling spiral galaxies. It is much less clear how galaxies are affected by the much lower ram pressures found in galaxy groups, or if other environmental processes begin to dominate. Given that >50% of galaxies in the local volume reside in groups, it is vital we gain new insights into which mechanisms drive the SFR-density relation in groups. The proposed H(alpha) imaging will allow us to resolve where star-formation is occuring in each galaxy. This can effectively discriminate between ram-pressure stripping characterized by truncated H(alpha) disks, the much gentler starvation mechanism which produces anemic spirals, and nuclear star-bursts triggered by low-velocity encounters which should be most frequent in groups.

KPNO 0.9m H(alpha) Imaging Survey of ``Transforming Galaxies'' in Local Galaxy Groups

NASA Astrophysics Data System (ADS)

Haines, Christopher; O'Sullivan, Ewan; Raychaudhury, Somak; Egami, Eiichi; Campusano, Luis

2012-08-01

We propose to use the KPNO 0.9-m telescope to obtain panoramic H(alpha) imaging of ~135 galaxies in ten nearby galaxy groups (60- 80 Mpc) from the Complete Local-Volume Groups Sample (CLoGS). In rich clusters ram-pressure stripping has been shown to be very effective at removing the gas contents and quenching star formation in infalling spiral galaxies. It is much less clear how galaxies are affected by the much lower ram pressures found in galaxy groups, or if other environmental processes begin to dominate. Given that >50% of galaxies in the local volume reside in groups, it is vital that we gain new insights into which mechanisms drive the SFR-density relation in groups. The proposed H(alpha) imaging will allow us to resolve where star-formation is occurring in each galaxy. This can effectively discriminate between ram-pressure stripping characterized by truncated H(alpha) disks, the much gentler starvation mechanism which produces anemic spirals, and nuclear starbursts triggered by low-velocity encounters and mergers which should be most frequent in groups.

46 CFR 109.577 - Helicopter fueling.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 4 2011-10-01 2011-10-01 false Helicopter fueling. 109.577 Section 109.577 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) A-MOBILE OFFSHORE DRILLING UNITS OPERATIONS Miscellaneous § 109.577 Helicopter fueling. (a) The master or person in charge shall designate persons to...

46 CFR 109.577 - Helicopter fueling.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 4 2012-10-01 2012-10-01 false Helicopter fueling. 109.577 Section 109.577 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) A-MOBILE OFFSHORE DRILLING UNITS OPERATIONS Miscellaneous § 109.577 Helicopter fueling. (a) The master or person in charge shall designate persons to...

46 CFR 109.577 - Helicopter fueling.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 4 2014-10-01 2014-10-01 false Helicopter fueling. 109.577 Section 109.577 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) A-MOBILE OFFSHORE DRILLING UNITS OPERATIONS Miscellaneous § 109.577 Helicopter fueling. (a) The master or person in charge shall designate persons to...

46 CFR 109.577 - Helicopter fueling.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 4 2013-10-01 2013-10-01 false Helicopter fueling. 109.577 Section 109.577 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) A-MOBILE OFFSHORE DRILLING UNITS OPERATIONS Miscellaneous § 109.577 Helicopter fueling. (a) The master or person in charge shall designate persons to...

46 CFR 109.577 - Helicopter fueling.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Helicopter fueling. 109.577 Section 109.577 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) A-MOBILE OFFSHORE DRILLING UNITS OPERATIONS Miscellaneous § 109.577 Helicopter fueling. (a) The master or person in charge shall designate persons to...

Smooth H I Low Column Density Outskirts in Nearby Galaxies

NASA Astrophysics Data System (ADS)

Ianjamasimanana, R.; Walter, Fabian; de Blok, W. J. G.; Heald, George H.; Brinks, Elias

2018-06-01

The low column density gas at the outskirts of galaxies as traced by the 21 cm hydrogen line emission (H I) represents the interface between galaxies and the intergalactic medium, i.e., where galaxies are believed to get their supply of gas to fuel future episodes of star formation. Photoionization models predict a break in the radial profiles of H I at a column density of ∼5 × 1019 cm‑2 due to the lack of self-shielding against extragalactic ionizing photons. To investigate the prevalence of such breaks in galactic disks and to characterize what determines the potential edge of the H I disks, we study the azimuthally averaged H I column density profiles of 17 nearby galaxies from the H I Nearby Galaxy Survey and supplemented in two cases with published Hydrogen Accretion in LOcal GAlaxieS data. To detect potential faint H I emission that would otherwise be undetected using conventional moment map analysis, we line up individual profiles to the same reference velocity and average them azimuthally to derive stacked radial profiles. To do so, we use model velocity fields created from a simple extrapolation of the rotation curves to align the profiles in velocity at radii beyond the extent probed with the sensitivity of traditional integrated H I maps. With this method, we improve our sensitivity to outer-disk H I emission by up to an order of magnitude. Except for a few disturbed galaxies, none show evidence of a sudden change in the slope of the H I radial profiles: the alleged signature of ionization by the extragalactic background.

DETECTION OF H i IN EMISSION IN THE LY α EMITTING GALAXY HARO 11

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pardy, Stephen A.; Cannon, John M.; Östlin, Göran

We present the first robust detection of H i 21 cm emission in the blue compact galaxy Haro 11 using the 100 m Robert C. Byrd Green Bank Telescope (GBT). Haro 11 is a luminous blue compact galaxy with emission in both Ly α and the Lyman continuum. We detect (5.1 ± 0.7 × 10{sup 8}) M {sub ⊙} of H i gas at an assumed distance of 88 Mpc, making this galaxy H i deficient compared to other local galaxies with similar optical properties. Given this small H i mass, Haro 11 has an elevated M{sub H2}/ M{sub Hi} ratio and a verymore » low gas fraction compared to most local galaxies, and contains twice as much mass in ionized hydrogen as in neutral hydrogen. The H i emission has a linewidth of 71 km s{sup −}1 and is offset 60 km s{sup −1} redward of the optical line center. It is undergoing a starburst after a recent merger that has elevated the star formation rate, and will deplete the gas supply in <0.2 Gyr. Although this starburst has elevated the star formation rate (SFR) compared to galaxies with similar H i masses and line widths, Haro 11 matches a trend of lower gas fractions toward higher SFRs and is below the general trend of increasing H i mass with increasing luminosity. Taken together, our results paint Haro 11 as a standard low-mass galaxy that is undergoing an unusually efficient star formation episode.« less

The Effect of Halo Mass on the H I Content of Galaxies in Groups and Clusters

NASA Astrophysics Data System (ADS)

Yoon, Ilsang; Rosenberg, Jessica L.

2015-10-01

We combine data from the Sloan Digital Sky Survey (SDSS) and the Arecibo Legacy Fast ALFA Survey (ALFALFA) to study the cold atomic gas content of galaxies in groups and clusters in the local universe. A careful cross-matching of galaxies in the SDSS, ALFALFA, and SDSS group catalogs provides a sample of group galaxies with stellar masses {10}8.4{M}⊙ ≤slant {M}*≤slant {10}10.6{M}⊙ and group halo masses {10}12.5{h}-1{M}⊙ ≤slant {M}h≤slant {10}15.0{h}-1{M}⊙ . Controlling our sample in stellar mass and redshift, we find no significant radial variation in the galaxy H i gas-to-stellar mass ratio for the halo mass range in our sample. However, the fraction of galaxies detected in ALFALFA declines steadily toward the centers of groups, with the effect being most prominent in the most massive halos. In the outskirts of massive halos a hint of a depressed detection fraction for low-mass galaxies suggests pre-processing that decreases the H i in these galaxies before they fall into massive clusters. We interpret the decline in the ALFALFA detection of galaxies in the context of a threshold halo mass for ram pressure stripping for a given galaxy stellar mass. The lack of an observable decrease in the galaxy H i gas-to-stellar mass ratio with the position of galaxies within groups and clusters highlights the difficulty of detecting the impact of environment on the galaxy H i content in a shallow H i survey.

Significant Enhancement of H2 Formation in Disk Galaxies under Strong Ram Pressure

NASA Astrophysics Data System (ADS)

Henderson, Benjamin; Bekki, Kenji

2016-05-01

We show for the first time that H2 formation on dust grains can be enhanced in disk galaxies under strong ram pressure (RP). We numerically investigate how the time evolution of H I and H2 components in disk galaxies orbiting a group/cluster of galaxies can be influenced by the hydrodynamical interaction between the gaseous components of the galaxies and the hot intracluster medium. We find that compression of H I caused by RP increases H2 formation in disk galaxies before RP rapidly strips H I, cutting off the fuel supply and causing a drop in H2 density. We also find that the level of this H2 formation enhancement in a disk galaxy under RP depends on the mass of its host cluster dark matter halo, the initial positions and velocities of the disk galaxy, and the disk inclination angle with respect to the orbital plane. We demonstrate that dust growth is a key factor in the evolution of the H I and H2 mass in disk galaxies under strong RP. We discuss how the correlation between H2 fractions and surface gas densities of disk galaxies evolves with time in the galaxies under RP. We also discuss whether galaxy-wide star formation rates (SFRs) in cluster disk galaxies can be enhanced by RP if the SFRs depend on H2 densities.

New lessons from the H I size-mass relation of galaxies

NASA Astrophysics Data System (ADS)

Wang, Jing; Koribalski, Bärbel S.; Serra, Paolo; van der Hulst, Thijs; Roychowdhury, Sambit; Kamphuis, Peter; Chengalur, Jayaram N.

2016-08-01

We revisit the H I size-mass (D_{H I}-MH I) relation of galaxies with a sample of more than 500 nearby galaxies covering over five orders of magnitude in H I mass and more than 10 B-band magnitudes. The relation is remarkably tight with a scatter σ ˜ 0.06 dex, or 14 per cent. The scatter does not change as a function of galaxy luminosity, H I richness or morphological type. The relation is linked to the fact that dwarf and spiral galaxies have a homogeneous radial profile of H I surface density in the outer regions when the radius is normalized by DH I. The early-type disc galaxies typically have shallower H I radial profiles, indicating a different gas accretion history. We argue that the process of atomic-to-molecular gas conversion or star formation cannot explain the tightness of the DH I-MH I relation. This simple relation puts strong constraints on simulation models for galaxy formation.

The Global Implications of the Hard X-ray Excess in Type 1 AGN

NASA Astrophysics Data System (ADS)

Tatum, Malachi; Turner, T. J.; Miller, L.; Reeves, J. N.

2012-09-01

Suzaku observations of 1H 0419-577 and PDS 456 revealed a marked 'hard excess' of flux above 10 keV, likely due to the presence of a Compton-thick absorber covering a large fraction of the continuum source. The discovery is intriguing, given the clear view to the optical BLR in type 1 objects. These results motivated an exploratory study of the hard excess phenomenon in the local type 1 AGN population, using the Swift Burst Alert Telescope (BAT). We selected radio quiet type 1-1.9 AGN from the 58-month BAT catalog. The hardness of the X-ray spectrum, combined with measurements of the equivalent width of Fe Ka emission suggest that type 1 X-ray spectra are shaped by an ensemble of Compton-thick clouds, partially covering the continuum. I discuss our methodology, the observational findings & possible location of the Compton-thick gas.

Distribution and kinematics of H I in the active elliptical galaxy NGC 1052

DOE Office of Scientific and Technical Information (OSTI.GOV)

van Gorkom, J.H.; Knapp, G.R.; Raimond, E.

The H I distribution in the active elliptical galaxy NGC 1052 has been mapped at a resolution of 1 arcmin with the VLA. The H I structure is about three times the size of the optical galaxy and is roughly perpendicular to its major axis. The H I has a circular velocity of approx.200 km/s, roughly constant with radius; the mass of the galaxy is 1.5 x 10/sup 11/ M/sub sun/ at a radius of 16 kpc (D = 13.4 Mpc), and the mass to blue luminosity ratio at this radius is M/L/sub B/ approx.15 M/sub sun//L/sub sun/. H Imore » absorption is seen against the central radio continuum source, at both the systemic velocity and at redshifted velocities. The gas in NGC 1052, as in other ellipticals, has a rotation axis that is not aligned with the stellar rotation axis (the difference is 63/sup 0/) and a mean specific angular momentum that is considerably larger than that of the stars. The H I distribution is unusually irregular. In the southwest region of the galaxy, the distribution shows what appears to be a tidal tail, suggesting that the H I may have been acquired about 10/sup 9/ years ago. The presence of dust associated with the H I and the distribution and kinematics of the H I are consistent with capture of gas from a gas-rich dwarf or spiral. In the inner regions of the galaxy (r<5 kpc) the H I velocity field shows evidence of noncircular orbits and therefore possibly of a triaxial mass distribution for the galaxy. Alternatively the gas could be falling in toward the center.« less

25 CFR 577.6 - Service.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 25 Indians 2 2010-04-01 2010-04-01 false Service. 577.6 Section 577.6 Indians NATIONAL INDIAN GAMING COMMISSION, DEPARTMENT OF THE INTERIOR COMPLIANCE AND ENFORCEMENT PROVISIONS APPEALS BEFORE THE... representative. (e) In computing any period of time prescribed for filing and serving a document, the first day...

Measurement of a Cosmographic Distance Ratio with Galaxy and Cosmic Microwave Background Lensing.

PubMed

Miyatake, Hironao; Madhavacheril, Mathew S; Sehgal, Neelima; Slosar, Anže; Spergel, David N; Sherwin, Blake; van Engelen, Alexander

2017-04-21

We measure the gravitational lensing shear signal around dark matter halos hosting constant mass galaxies using light sources at z∼1 (background galaxies) and at the surface of last scattering at z∼1100 (the cosmic microwave background). The galaxy shear measurement uses data from the CFHTLenS survey, and the microwave background shear measurement uses data from the Planck satellite. The ratio of shears from these cross-correlations provides a purely geometric distance measurement across the longest possible cosmological lever arm. This is because the matter distribution around the halos, including uncertainties in galaxy bias and systematic errors such as miscentering, cancels in the ratio for halos in thin redshift slices. We measure this distance ratio in three different redshift slices of the constant mass (CMASS) sample and combine them to obtain a 17% measurement of the distance ratio, r=0.390_{-0.062}^{+0.070}, at an effective redshift of z=0.53. This is consistent with the predicted ratio from the Planck best-fit cold dark matter model with a cosmological constant cosmology of r=0.419.

Predicting the Redshift 2 H-Alpha Luminosity Function Using [OIII] Emission Line Galaxies

NASA Technical Reports Server (NTRS)

Mehta, Vihang; Scarlata, Claudia; Colbert, James W.; Dai, Y. S.; Dressler, Alan; Henry, Alaina; Malkan, Matt; Rafelski, Marc; Siana, Brian; Teplitz, Harry I.;

Extending the modeling of the anisotropic galaxy power spectrum to k = 0.4 h Mpc{sup −1}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hand, Nick; Seljak, Uroš; Beutler, Florian

We present a model for the redshift-space power spectrum of galaxies and demonstrate its accuracy in describing the monopole, quadrupole, and hexadecapole of the galaxy density field down to scales of k = 0.4 h Mpc{sup −1}. The model describes the clustering of galaxies in the context of a halo model and the clustering of the underlying halos in redshift space using a combination of Eulerian perturbation theory and N -body simulations. The modeling of redshift-space distortions is done using the so-called distribution function approach. The final model has 13 free parameters, and each parameter is physically motivated rather thanmore » a nuisance parameter, which allows the use of well-motivated priors. We account for the Finger-of-God effect from centrals and both isolated and non-isolated satellites rather than using a single velocity dispersion to describe the combined effect. We test and validate the accuracy of the model on several sets of high-fidelity N -body simulations, as well as realistic mock catalogs designed to simulate the BOSS DR12 CMASS data set. The suite of simulations covers a range of cosmologies and galaxy bias models, providing a rigorous test of the level of theoretical systematics present in the model. The level of bias in the recovered values of f σ{sub 8} is found to be small. When including scales to k = 0.4 h Mpc{sup −1}, we find 15-30% gains in the statistical precision of f σ{sub 8} relative to k = 0.2 h Mpc{sup −1} and a roughly 10–15% improvement for the perpendicular Alcock-Paczynski parameter α{sub ⊥}. Using the BOSS DR12 CMASS mocks as a benchmark for comparison, we estimate an uncertainty on f σ{sub 8} that is ∼10–20% larger than other similar Fourier-space RSD models in the literature that use k ≤ 0.2 h Mpc{sup −1}, suggesting that these models likely have a too-limited parametrization.« less

SIGNIFICANT ENHANCEMENT OF H{sub 2} FORMATION IN DISK GALAXIES UNDER STRONG RAM PRESSURE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Henderson, Benjamin; Bekki, Kenji

We show for the first time that H{sub 2} formation on dust grains can be enhanced in disk galaxies under strong ram pressure (RP). We numerically investigate how the time evolution of H i and H{sub 2} components in disk galaxies orbiting a group/cluster of galaxies can be influenced by the hydrodynamical interaction between the gaseous components of the galaxies and the hot intracluster medium. We find that compression of H i caused by RP increases H{sub 2} formation in disk galaxies before RP rapidly strips H i, cutting off the fuel supply and causing a drop in H{sub 2}more » density. We also find that the level of this H{sub 2} formation enhancement in a disk galaxy under RP depends on the mass of its host cluster dark matter halo, the initial positions and velocities of the disk galaxy, and the disk inclination angle with respect to the orbital plane. We demonstrate that dust growth is a key factor in the evolution of the H i and H{sub 2} mass in disk galaxies under strong RP. We discuss how the correlation between H{sub 2} fractions and surface gas densities of disk galaxies evolves with time in the galaxies under RP. We also discuss whether galaxy-wide star formation rates (SFRs) in cluster disk galaxies can be enhanced by RP if the SFRs depend on H{sub 2} densities.« less

The Effect of Filaments and Tendrils on the H I Content of Galaxies

NASA Astrophysics Data System (ADS)

Crone Odekon, Mary; Hallenbeck, Gregory; Haynes, Martha P.; Koopmann, Rebecca A.; Phi, An; Wolfe, Pierre-Francois

2018-01-01

We use the ALFALFA H I survey to examine whether the cold gas reservoirs of galaxies are inhibited or enhanced in large-scale filaments. Our sample includes 9947 late-type galaxies with H I detections and 4236 late-type galaxies with well-determined H I detection limits that we incorporate using survival analysis statistics. We find that, even at fixed local density and stellar mass, and with group galaxies removed, the H I deficiency of galaxies in the stellar mass range 8.5 < log(M/M ⊙) < 10.5 decreases with distance from the filament spine, suggesting that galaxies are cut off from their supply of cold gas in this environment. We also find that, at fixed local density and stellar mass, the galaxies that are the most gas-rich are those in small, correlated “tendril” structures within voids: although galaxies in tendrils are in significantly denser environments, on average, than galaxies in voids, they are not redder or more H I deficient. This stands in contrast to the fact that galaxies in tendrils are more massive than those in voids, suggesting a more advanced stage of evolution. Finally, at fixed stellar mass and color, galaxies closer to the filament spine, or in high-density environments, are more deficient in H I. This fits a picture where, as galaxies enter denser regions, they first lose H I gas and then redden as star formation is reduced.

Narrow-Line Seyfert 1 Galaxies

NASA Technical Reports Server (NTRS)

Leighly, Karen M.

2000-01-01

The primary work during this year has been the analysis and interpretation of our HST spectra from two extreme Narrow-line Seyfert 1 galaxies (NLS1s) Infrared Astronomy Satellite (IRAS) 13224-3809 and 1H 0707-495. This work has been presented as an invited talk at the workshop entitled "Observational and theoretical progress in the Study of Narrow-line Seyfert 1 Galaxies" held in Bad Honnef, Germany December 8-11, as a contributed talk at the January 2000 AAS meeting in Atlanta, Georgia, and as a contributed talk at the workshop "Probing the Physics of Active Galactic Nuclei by Multiwavelength Monitoring" held at Goddard Space Flight Center June 20-22, 2000.

A multiwavelength survey of H I-excess galaxies with surprisingly inefficient star formation

NASA Astrophysics Data System (ADS)

Geréb, K.; Janowiecki, S.; Catinella, B.; Cortese, L.; Kilborn, V.

2018-05-01

We present the results of a multiwavelength survey of H I-excess galaxies, an intriguing population with large H I reservoirs associated with little current star formation. These galaxies have stellar masses M⋆ > 1010 M⊙, and were identified as outliers in the gas fraction versus NUV-r colour and stellar mass surface density scaling relations based on the GALEX Arecibo SDSS Survey (GASS). We obtained H I interferometry with the Giant Metrewave Radio Telescope, Keck optical long-slit spectroscopy, and deep optical imaging (where available) for four galaxies. Our analysis reveals multiple possible reasons for the H I excess in these systems. One galaxy, AGC 10111, shows an H I disc that is counter-rotating with respect to the stellar bulge, a clear indication of external origin of the gas. Another galaxy appears to host a Malin 1-type disc, where a large specific angular momentum has to be invoked to explain the extreme M_{H I}/M⋆ ratio of 166 per cent. The other two galaxies have early-type morphology with very high gas fractions. The lack of merger signatures (unsettled gas, stellar shells, and streams) in these systems suggests that these gas-rich discs have been built several Gyr ago, but it remains unclear how the gas reservoirs were assembled. Numerical simulations of large cosmological volumes are needed to gain insight into the formation of these rare and interesting systems.

STAR-FORMING GALAXIES IN THE HERCULES CLUSTER: H{alpha} IMAGING OF A2151

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cedres, Bernabe; Iglesias-Paramo, Jorge; VIlchez, Jose Manuel

2009-09-15

This paper presents the first results of an H{alpha} imaging survey of galaxies in the central regions of the A2151 cluster. A total of 50 sources were detected in H{alpha}, from which 41 were classified as secure members of the cluster and 2 as likely members based on spectroscopic and photometric redshift considerations. The remaining seven galaxies were classified as background contaminants and thus excluded from our study on the H{alpha} properties of the cluster. The morphologies of the 43 H{alpha} selected galaxies range from grand design spirals and interacting galaxies to blue compacts and tidal dwarfs or isolated extragalacticmore » H II regions, spanning a range of magnitudes of -21 {<=} M{sub B} {<=} -12.5 mag. From these 43 galaxies, 7 have been classified as active galactic nucleus (AGN) candidates. These AGN candidates follow the L(H{alpha}) versus M{sub B} relationship of the normal galaxies, implying that the emission associated with the nuclear engine has a rather secondary impact on the total H{alpha} emission of these galaxies. A comparison with the clusters Coma and A1367 and a sample of field galaxies has shown the presence of cluster galaxies with L(H{alpha}) lower than expected for their M{sub B} , a consequence of the cluster environment. This fact results in differences in the L(H{alpha}) versus EW(H{alpha}) and L(H{alpha}) distributions of the clusters with respect to the field, and in cluster-to-cluster variations of these quantities, which we propose are driven by a global cluster property as the total mass. In addition, the cluster H{alpha} emitting galaxies tend to avoid the central regions of the clusters, again with different intensity depending on the cluster total mass. For the particular case of A2151, we find that most H{alpha} emitting galaxies are located close to the regions with the higher galaxy density, offset from the main X-ray peak. Overall, we conclude that both the global cluster environment and the cluster merging

Galaxy population properties of the massive X-ray luminous galaxy cluster XDCP J0044.0-2033 at z = 1.58. Red-sequence formation, massive galaxy assembly, and central star formation activity

NASA Astrophysics Data System (ADS)

Fassbender, R.; Nastasi, A.; Santos, J. S.; Lidman, C.; Verdugo, M.; Koyama, Y.; Rosati, P.; Pierini, D.; Padilla, N.; Romeo, A. D.; Menci, N.; Bongiorno, A.; Castellano, M.; Cerulo, P.; Fontana, A.; Galametz, A.; Grazian, A.; Lamastra, A.; Pentericci, L.; Sommariva, V.; Strazzullo, V.; Šuhada, R.; Tozzi, P.

2014-08-01

cluster-core population comprises post-quenched galaxies transitioning toward the red sequence at intermediate magnitudes, while additionally a significant blue-cloud population of faint star-forming galaxies is present even in the densest central regions. Based on a color-color selection performed to separate different cluster galaxy types, we find that the blue star-forming population is concentrated in clumpy structures and dominates in particular at and beyond the R500 radius. On the other hand, the fraction of post-starburst galaxies steadily increases toward the center, while the red-locus population and red-sequence transition galaxies seem to reach their peak fractions already at intermediate cluster-centric radii of about r ~ 200 kpc. Conclusions: Our observations support the scenario in which the dominant effect of the dense z ≃ 1.6 cluster environment is an accelerated mass-assembly timescale (~1 Gyr or shorter) through merging activity that is responsible for driving core galaxies across the mass-quenching threshold of log (M∗/M⊙) ≃ 10.4. Beyond this mass limit, star formation is suppressed on timescales of ~1 Gyr, while the direct environmental quenching process seems to be subdominant and is acting on significantly longer timescales (~2-3 Gyr). Based on observations under programme ID 084.A-0844, 087.A-0351, and 089.A-0419 collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile.J- and Ks-band FITS files are 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/568/A5

C+/H2 gas in star-forming clouds and galaxies

NASA Astrophysics Data System (ADS)

Nordon, Raanan; Sternberg, Amiel

2016-11-01

We present analytic theory for the total column density of singly ionized carbon (C+) in the optically thick photon dominated regions (PDRs) of far-UV irradiated (star-forming) molecular clouds. We derive a simple formula for the C+ column as a function of the cloud (hydrogen) density, the far-UV field intensity, and metallicity, encompassing the wide range of galaxy conditions. When assuming the typical relation between UV and density in the cold neutral medium, the C+ column becomes a function of the metallicity alone. We verify our analysis with detailed numerical PDR models. For optically thick gas, most of the C+ column is mixed with hydrogen that is primarily molecular (H2), and this `C+/H2' gas layer accounts for almost all of the `CO-dark' molecular gas in PDRs. The C+/H2 column density is limited by dust shielding and is inversely proportional to the metallicity down to ˜0.1 solar. At lower metallicities, H2 line blocking dominates and the C+/H2 column saturates. Applying our theory to CO surveys in low-redshift spirals, we estimate the fraction of C+/H2 gas out of the total molecular gas to be typically ˜0.4. At redshifts 1 < z < 3 in massive disc galaxies the C+/H2 gas represents a very small fraction of the total molecular gas (≲ 0.16). This small fraction at high redshifts is due to the high gas surface densities when compared to local galaxies.

H I-SELECTED GALAXIES IN THE SLOAN DIGITAL SKY SURVEY. II. THE COLORS OF GAS-RICH GALAXIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

West, Andrew A.; Garcia-Appadoo, Diego A.; Dalcanton, Julianne J.

2009-09-15

We utilize color information for an H I-selected sample of 195 galaxies to explore the star formation histories and physical conditions that produce the observed colors. We show that the H I selection creates a significant offset toward bluer colors that can be explained by enhanced recent bursts of star formation. There is also no obvious color bimodality, because the H I selection restricts the sample to bluer, actively star-forming systems, diminishing the importance of the red sequence. Rising star formation rates are still required to explain the colors of galaxies bluer than g - r< 0.3. We also demonstratemore » that the colors of the bluest galaxies in our sample are dominated by emission lines and that stellar population synthesis models alone (without emission lines) are not adequate for reproducing many of the galaxy colors. These emission lines produce large changes in the r - i colors but leave the g - r color largely unchanged. In addition, we find an increase in the dispersion of galaxy colors at low masses that may be the result of a change in the star formation process in low-mass galaxies.« less

Broad line emission from iron K- and L-shell transitions in the active galaxy 1H 0707-495.

PubMed

Fabian, A C; Zoghbi, A; Ross, R R; Uttley, P; Gallo, L C; Brandt, W N; Blustin, A J; Boller, T; Caballero-Garcia, M D; Larsson, J; Miller, J M; Miniutti, G; Ponti, G; Reis, R C; Reynolds, C S; Tanaka, Y; Young, A J

2009-05-28

Since the 1995 discovery of the broad iron K-line emission from the Seyfert galaxy MCG-6-30-15 (ref. 1), broad iron K lines have been found in emission from several other Seyfert galaxies, from accreting stellar-mass black holes and even from accreting neutron stars. The iron K line is prominent in the reflection spectrum created by the hard-X-ray continuum irradiating dense accreting matter. Relativistic distortion of the line makes it sensitive to the strong gravity and spin of the black hole. The accompanying iron L-line emission should be detectable when the iron abundance is high. Here we report the presence of both iron K and iron L emission in the spectrum of the narrow-line Seyfert 1 galaxy 1H 0707-495. The bright iron L emission has enabled us to detect a reverberation lag of about 30 s between the direct X-ray continuum and its reflection from matter falling into the black hole. The observed reverberation timescale is comparable to the light-crossing time of the innermost radii around a supermassive black hole. The combination of spectral and timing data on 1H 0707-495 provides strong evidence that we are witnessing emission from matter within a gravitational radius, or a fraction of a light minute, from the event horizon of a rapidly spinning, massive black hole.

Full-disc 13CO(1-0) mapping across nearby galaxies of the EMPIRE survey and the CO-to-H2 conversion factor

NASA Astrophysics Data System (ADS)

Cormier, D.; Bigiel, F.; Jiménez-Donaire, M. J.; Leroy, A. K.; Gallagher, M.; Usero, A.; Sandstrom, K.; Bolatto, A.; Hughes, A.; Kramer, C.; Krumholz, M. R.; Meier, D. S.; Murphy, E. J.; Pety, J.; Rosolowsky, E.; Schinnerer, E.; Schruba, A.; Sliwa, K.; Walter, F.

2018-04-01

Carbon monoxide (CO) provides crucial information about the molecular gas properties of galaxies. While 12CO has been targeted extensively, isotopologues such as 13CO have the advantage of being less optically thick and observations have recently become accessible across full galaxy discs. We present a comprehensive new data set of 13CO(1-0) observations with the IRAM 30-m telescope of the full discs of nine nearby spiral galaxies from the EMPIRE survey at a spatial resolution of ˜1.5 kpc. 13CO(1-0) is mapped out to 0.7 - 1 r25 and detected at high signal-to-noise ratio throughout our maps. We analyse the 12CO(1-0)-to-13CO(1-0) ratio (ℜ) as a function of galactocentric radius and other parameters such as the 12CO(2-1)-to-12CO(1-0) intensity ratio, the 70-to-160 μm flux density ratio, the star formation rate surface density, the star formation efficiency, and the CO-to-H2 conversion factor. We find that ℜ varies by a factor of 2 at most within and amongst galaxies, with a median value of 11 and larger variations in the galaxy centres than in the discs. We argue that optical depth effects, most likely due to changes in the mixture of diffuse/dense gas, are favoured explanations for the observed ℜ variations, while abundance changes may also be at play. We calculate a spatially resolved 13CO(1-0)-to-H2 conversion factor and find an average value of 1.0 × 1021 cm-2 (K km s-1)-1 over our sample with a standard deviation of a factor of 2. We find that 13CO(1-0) does not appear to be a good predictor of the bulk molecular gas mass in normal galaxy discs due to the presence of a large diffuse phase, but it may be a better tracer of the mass than 12CO(1-0) in the galaxy centres where the fraction of dense gas is larger.

Spectroscopy of luminous infrared galaxies at 2 microns: 1. The ultraluminous galaxies (L(sub IR) approximately greater than 10 (exp 12) solar luminosity)

NASA Technical Reports Server (NTRS)

Goldader, Jeffrey D.; Joseph, R. D.; Doyon, Rene; Sanders, D. B.

1995-01-01

We present high-quality spectra covering the K window at a resolving power of 340 for a sample of 13 ultraluminous (L(sub IR) approximately greater than 10(exp 12) solar luminosity) infrared-selected galaxies, and line fluxes for a comparison sample of 24 lower luminosity galaxies. The 2 micrometers spectra of 10 of the ultraluminous galaxies are characterized by emission and absorption features commonly associated with stars and star formation; two others have the red power-law spectra and Br gamma line widths of Seyfert 1 galaxies; the final galaxy has strong emission from hot dust. We have found no broad-line active nuclei not already known from optical observations, despite the fact that the extinction at 2 micrometers is 1/10 that at optical wavelengths; any putative Seyfert 1 nuclei must be deeply buried. Powerful continua and emission lines from H2 and Br gamma are detected in all the ultraluminous galaxies. Comparing the H2 1-0 S(1), Br gamma, and 2 micrometers and far-infrared luminosities to those of the lower luminosity galaxies yields several major results. First, the dereddened Br gamma emission, relative to the far-infrared luminosity is significantly depressed in the ultraluminous sample, when compared to the lower luminosity galaxies. Five of the ultraluminous galaxies have L(sub Br gamma)L(sub IR) ratios lower than for any of the comparison objects. Second, the H2 1-0 S(1) luminosity is also responsible, directly or indirectly, for producing the excited H2, and that the H2 apparently comes from optically thin regions in both classes of objects. Third, eight of the 13 ultraluminous systems have lower 2 micrometers/far-infrared luminosity ratios than any of the lower luminosity galaxies, and five of these are the galaxies also deficient in Br gamma. These three findings may be understood if the the H2, Br gamma, and 2 mircometers continua in the ultraluminous galaxies arise from spatially distinct regions, with the continuum and Br gamma largely

VIVA (VLA Imaging of Virgo in Atomic gas): H I Stripping in Virgo Galaxies

NASA Astrophysics Data System (ADS)

Chung, A.; van Gorkom, J. H.; Crowl, H.; Kenney, J. D. P.; Vollmer, B.

2008-08-01

We present results of a new Very Large Array survey of 53 Virgo galaxies (48 spirals and 5 dwarf/irregular systems). The goal is to study how the H I gas properties are affected by the cluster environment. The survey covers galaxies in a wide range of densities from the center of the cluster to more than 3 Mpc from M 87. The gas is imaged down to a column-density sensitivity of a few times 1019cm-2. We find examples of gas stripping at all stages. Within ˜0.5 Mpc from M 87, most galaxies are severely H I stripped. The H I disks are truncated to well within the optical disks. While the H I looks asymmetric, the outer stellar disks look undisturbed. The fact that only the gas and not the stars has been stripped suggests that those galaxies have been affected by the hot and dense cluster gas. Interestingly we also find a few truncated disks at large projected distances from the center. Although some of these may have been stripped while crossing the cluster core, a detailed population-synthesis study of the outer disk of one of these shows that star formation was terminated recently. The time since stripping is too short for the galaxy to have traveled from the core to its current location. So at least one galaxy has lost its gas from the outer disk by another mechanism than ram-pressure stripping in the dense cluster core. At intermediate- to low-density regions (>0.6 Mpc) we find H I tails with various lengths. We find seven galaxies with long one-sided H I tails pointing away from M 87. The galaxies are at 0.6-1 Mpc from M 87. Since these galaxies are only mildly H I deficient and the tails point away from M 87, these galaxies are probably falling into the cluster for the first time on highly radial orbits. For all but two of the galaxies the estimated ram pressure at their location in the cluster would be sufficient to pull out the H I in the very outer disks. One galaxy also looks optically disturbed and a simulation suggests that a combination of ram pressure

2D Bayesian automated tilted-ring fitting of disc galaxies in large H I galaxy surveys: 2DBAT

NASA Astrophysics Data System (ADS)

Oh, Se-Heon; Staveley-Smith, Lister; Spekkens, Kristine; Kamphuis, Peter; Koribalski, Bärbel S.

2018-01-01

We present a novel algorithm based on a Bayesian method for 2D tilted-ring analysis of disc galaxy velocity fields. Compared to the conventional algorithms based on a chi-squared minimization procedure, this new Bayesian-based algorithm suffers less from local minima of the model parameters even with highly multimodal posterior distributions. Moreover, the Bayesian analysis, implemented via Markov Chain Monte Carlo sampling, only requires broad ranges of posterior distributions of the parameters, which makes the fitting procedure fully automated. This feature will be essential when performing kinematic analysis on the large number of resolved galaxies expected to be detected in neutral hydrogen (H I) surveys with the Square Kilometre Array and its pathfinders. The so-called 2D Bayesian Automated Tilted-ring fitter (2DBAT) implements Bayesian fits of 2D tilted-ring models in order to derive rotation curves of galaxies. We explore 2DBAT performance on (a) artificial H I data cubes built based on representative rotation curves of intermediate-mass and massive spiral galaxies, and (b) Australia Telescope Compact Array H I data from the Local Volume H I Survey. We find that 2DBAT works best for well-resolved galaxies with intermediate inclinations (20° < i < 70°), complementing 3D techniques better suited to modelling inclined galaxies.

Measurement of a cosmographic distance ratio with galaxy and cosmic microwave background lensing

DOE PAGES

Miyatake, Hironao; Madhavacheril, Mathew S.; Sehgal, Neelima; ...

2017-04-17

We measure the gravitational lensing shear signal around dark matter halos hosting constant mass galaxies using light sources at z~1 (background galaxies) and at the surface of last scattering at z~1100 (the cosmic microwave background). The galaxy shear measurement uses data from the CFHTLenS survey, and the microwave background shear measurement uses data from the Planck satellite. The ratio of shears from these cross-correlations provides a purely geometric distance measurement across the longest possible cosmological lever arm. This is because the matter distribution around the halos, including uncertainties in galaxy bias and systematic errors such as miscentering, cancels in themore » ratio for halos in thin redshift slices. We measure this distance ratio in three different redshift slices of the constant mass (CMASS) sample and combine them to obtain a 17% measurement of the distance ratio, r = 0.390 +0.070 –0.062, at an effective redshift of z = 0.53. As a result, this is consistent with the predicted ratio from the Planck best-fit cold dark matter model with a cosmological constant cosmology of r = 0.419.« less

Far Outer Galaxy H II Regions

NASA Technical Reports Server (NTRS)

Rudolph, A. L.; deGues, E. J.; Brand, J.; Wouterloot, J. G. A.; Gross, Anthony R. (Technical Monitor)

1994-01-01

We have made a multifrequency (6, 3.6, and 2 cm), high-resolution (3"-6"), radio continuum survey of IRAS selected sources from the catalogue of Wouterloot & Brand (1989) to search for and study H II regions in the far outer Galaxy. We identified 31 sources in this catalog with well determined galactocentric distances, and with R approx.. greater than 15 kpc and L(sub FIR) approx.greater than 10(exp 4) solar luminosity, indicating the presence of high-mass star-formation. We have observed 11 of these sources with the Very Large Array (VLA). We observed the sources at 6 and 2 cm using "scaled arrays", making possible a direct and reliable comparison of the data at these two wavelengths for the determination of spectral indices. We detected a total of 12 radio sources, of which 10 have spectral indices consistent with optically-thin free-free emission from H II regions. Combined with previous VLA observations by other investigators, we have data on a total of 15 H II regions at galactocentric distances of 15 to 18.2kpc, among the most remote H II regions found in our Galaxy. The sizes of the H II regions range from approx. less than 0.10 to 2.3 pc. Using the measured fluxes and sizes, we determine the electron densities, emission measures, and excitation parameters of the H II regions, as well as the fluxes of Lyman continuum photons needed to keep the nebulae ionized. The sizes and electron densities are consistent with most of the sources detected in this survey being compact or ultracompact H II regions. Seven of the fifteen H II regions have sizes approx. less than 0.20 pc. Assuming simple pressure-driven expansion of the H II regions, these sizes indicate ages approx. less than 5 x 10(exp 4) yr, or only 1% of the lifetime of an O star, which implies an unlikely overabundance of O stars in the outer Galaxy. Thus, the large number of compact H II regions suggests that the time these regions spend in a compact phase must be much longer than their dynamical

A History of H I Stripping in Virgo: A Phase-space View of VIVA Galaxies

NASA Astrophysics Data System (ADS)

Yoon, Hyein; Chung, Aeree; Smith, Rory; Jaffé, Yara L.

2017-04-01

We investigate the orbital histories of Virgo galaxies at various stages of H I gas stripping. In particular, we compare the location of galaxies with different H I morphology in phase space. This method is a great tool for tracing the gas stripping histories of galaxies as they fall into the cluster. Most galaxies at the early stage of H I stripping are found in the first infall region of Virgo, while galaxies undergoing active H I stripping mostly appear to be falling in or moving out near the cluster core for the first time. Galaxies with severely stripped, yet symmetric, H I disks are found in one of two locations. Some are deep inside the cluster, but others are found in the cluster outskirts with low orbital velocities. We suggest that the latter group of galaxies belong to a “backsplash” population. These present the clearest candidates for backsplashed galaxies observationally identified to date. We further investigate the distribution of a large sample of H I-detected galaxies toward Virgo in phase space, confirming that most galaxies are stripped of their gas as they settle into the gravitational potential of the cluster. In addition, we discuss the impact of tidal interactions between galaxies and group preprocessing on the H I properties of the cluster galaxies, and link the associated star formation evolution to the stripping sequence of cluster galaxies.

ON THE COMPACT H II GALAXY UM 408 AS SEEN BY GMOS-IFU: PHYSICAL CONDITIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lagos, Patricio; Telles, Eduardo; Munoz-Tunon, Casiana

2009-06-15

We present Integral Field Unit GMOS-IFU data of the compact H II galaxy UM 408, obtained at the Gemini South telescope, in order to derive the spatial distribution of emission lines and line ratios, kinematics, plasma parameters, and oxygen abundances as well the integrated properties over an area of 3''x4.''4 equivalent with {approx}750 pc x 1100 pc located in the central part of the galaxy. The starburst in this area is resolved into two giant regions of about 1.''5 and 1'' ({approx}375 and {approx}250 pc) diameter, respectively and separated 1.5-2'' ({approx}500 pc). The extinction distribution concentrate its highest values closemore » but not coincident with the maxima of H{alpha} emission around each one of the detected regions. This indicates that the dust has been displaced from the exciting clusters by the action of their stellar winds. The ages of these two regions, estimated using H{beta} equivalent widths, suggest that they are coeval events of {approx}5 Myr with stellar masses of {approx}10{sup 4} M {sub sun}. We have also used [O III]/H{beta} and [S II]/H{alpha} ratio maps to explore the excitation mechanisms in this galaxy. Comparing the data points with theoretical diagnostic models, we found that all of them are consistent with excitation by photoionization by massive stars. The H{alpha} emission line was used to measure the radial velocity and velocity dispersion. The heliocentric radial velocity shows an apparent systemic motion where the east part of the galaxy is blueshifted, while the west part is redshifted, with a relative motion of {approx}10 km s{sup -1}. The velocity dispersion map shows supersonic values typical for extragalactic H II regions. We derived an integrated oxygen abundance of 12+log(O/H) = 7.87 summing over all spaxels in our field of view. An average value of 12+log(O/H) = 7.77 and a difference of {delta}(O/H) = 0.47 between the minimum and maximum values (7.58 {+-} 0.06-8.05 {+-} 0.04) were found, considering all data

Physical Conditions of the Interstellar Medium in Star-forming Galaxies at z1.5

NASA Technical Reports Server (NTRS)

Hayashi, Masao; Ly, Chun; Shimasaku, Kazuhiro; Motohara, Kentaro; Malkan, Matthew A.; Nagao, Tohru; Kashikawa, Nobunari; Goto, Ryosuke; Naito, Yoshiaki

2015-01-01

We present results from Subaru/FMOS near-infrared (NIR) spectroscopy of 118 star-forming galaxies at z approximately equal to 1.5 in the Subaru Deep Field. These galaxies are selected as [O II] lambda 3727 emitters at z approximately equal to 1.47 and 1.62 from narrow-band imaging. We detect H alpha emission line in 115 galaxies, [O III] lambda 5007 emission line in 45 galaxies, and H Beta, [N II] lambda 6584, and [S II]lambda lambda 6716, 6731 in 13, 16, and 6 galaxies, respectively. Including the [O II] emission line, we use the six strong nebular emission lines in the individual and composite rest-frame optical spectra to investigate physical conditions of the interstellar medium in star-forming galaxies at z approximately equal to 1.5. We find a tight correlation between H alpha and [O II], which suggests that [O II] can be a good star formation rate (SFR) indicator for galaxies at z approximately equal to 1.5. The line ratios of H alpha / [O II] are consistent with those of local galaxies. We also find that [O II] emitters have strong [O III] emission lines. The [O III]/[O II] ratios are larger than normal star-forming galaxies in the local Universe, suggesting a higher ionization parameter. Less massive galaxies have larger [O III]/[O II] ratios. With evidence that the electron density is consistent with local galaxies, the high ionization of galaxies at high redshifts may be attributed to a harder radiation field by a young stellar population and/or an increase in the number of ionizing photons from each massive star.

The Occurence of Nuclear Starbursts in Seyfert 1 Galaxies

NASA Astrophysics Data System (ADS)

Schinnerer, E.; Colbert, E.; Armus, L.; Scoville, N. Z.

2001-05-01

Medium resolution H and K band spectra with high angular reesolution were obtained for a small sample of nearby Seyfert galaxies using NIRSPEC at the Keck telescope. Recent studies with medium resolution have found evidence for a lack of powerful starbursts in Seyfert1 galaxies. Differences between the two Seyfert types might provide a challenge for the unified scheme proposed for Seyfert galaxies. A preliminary analysis indicates that most of the Seyfert1 galaxies do indeed show signs of circumnuclar star formation. Detailed modelling using population synthesis in conjunction with NIR spectral synthesis will allow to estimate the age, star formation history and mass of these stellar population.

The H I chronicles of LITTLE THINGS blue compact dwarf galaxies

NASA Astrophysics Data System (ADS)

Ashley, Trisha Lynn

Star formation occurs when the gas (mostly atomic hydrogen; H I) in a galaxy becomes disturbed, forming regions of high density gas, which then collapses to form stars. In dwarf galaxies it is still uncertain which processes contribute to star formation and how much they contribute to star formation. Blue compact dwarf (BCD) galaxies are low mass, low shear, gas rich galaxies that have high star formation rates when compared to other dwarf galaxies. What triggers the dense burst of star formation in BCDs but not other dwarfs is not well understood. It is often suggested that BCDs may have their starburst triggered by gravitational interactions with other galaxies, dwarf-dwarf galaxy mergers, or consumption of intergalactic gas. However, there are BCDs that appear isolated with respect to other galaxies, making an external disturbance unlikely. Here, I study six apparently isolated BCDs from the LITTLE THINGS sample in an attempt to understand what has triggered their burst of star formation. LITTLE THINGS is an H I survey of 41 dwarf galaxies. Each galaxy has high angular and velocity resolution H I data from the Very Large Array (VLA) telescope and ancillary stellar data. I use these data to study the detailed morphology and kinematics of each galaxy, looking for signatures of starburst triggers. In addition to the VLA data, I have collected Green Bank Telescope data for the six BCDs. These high sensitivity, low resolution data are used to search the surrounding area of each galaxy for extended emission and possible nearby companion galaxies. The VLA data show evidence that each BCD has likely experienced some form of external disturbance despite their apparent isolation. These external disturbances potentially seen in the sample include: ongoing/advanced dwarf-dwarf mergers, an interaction with an unknown external object, and external gas consumption. The GBT data result in no nearby, separate H I companions at the sensitivity of the data. These data therefore

A History of H i Stripping in Virgo: A Phase-space View of VIVA Galaxies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoon, Hyein; Chung, Aeree; Smith, Rory

We investigate the orbital histories of Virgo galaxies at various stages of H i gas stripping. In particular, we compare the location of galaxies with different H i morphology in phase space. This method is a great tool for tracing the gas stripping histories of galaxies as they fall into the cluster. Most galaxies at the early stage of H i stripping are found in the first infall region of Virgo, while galaxies undergoing active H i stripping mostly appear to be falling in or moving out near the cluster core for the first time. Galaxies with severely stripped, yetmore » symmetric, H i disks are found in one of two locations. Some are deep inside the cluster, but others are found in the cluster outskirts with low orbital velocities. We suggest that the latter group of galaxies belong to a “backsplash” population. These present the clearest candidates for backsplashed galaxies observationally identified to date. We further investigate the distribution of a large sample of H i-detected galaxies toward Virgo in phase space, confirming that most galaxies are stripped of their gas as they settle into the gravitational potential of the cluster. In addition, we discuss the impact of tidal interactions between galaxies and group preprocessing on the H i properties of the cluster galaxies, and link the associated star formation evolution to the stripping sequence of cluster galaxies.« less

The FMOS-COSMOS Survey of Star-forming Galaxies at Z ˜ 1.6. V: Properties of Dark Matter Halos Containing Hα Emitting Galaxies

NASA Astrophysics Data System (ADS)

Kashino, Daichi; More, Surhud; Silverman, John D.; Daddi, Emanuele; Renzini, Alvio; Sanders, David B.; Rodighiero, Giulia; Puglisi, Annagrazia; Kajisawa, Masaru; Valentino, Francesco; Kartaltepe, Jeyhan S.; Le Fèvre, Olivier; Nagao, Tohru; Arimoto, Nobuo; Sugiyama, Naoshi

2017-07-01

We study the properties of dark matter halos that contain star-forming galaxies at 1.43 ≤ z ≤ 1.74, using the FMOS-COSMOS survey. The sample consists of 516 objects with a detection of the Hα emission line, which represent the star forming population at this epoch, having a stellar mass range of 109.57 ≤ M */M ⊙ ≲ 1011.4 and a star-formation rate range of 15 ≲ SFR/(M ⊙ yr-1) ≲ 600. We measure the projected two-point correlation function while carefully taking into account observational biases, and find a significant clustering amplitude at scales of 0.04-10 h -1 cMpc, with a correlation length {r}0={5.26}-0.62+0.75 {h}-1 {cMpc} and a bias b={2.44}-0.32+0.38. We interpret our clustering measurement using a halo occupation distribution model. The sample galaxies appear to reside in halos with mass {M}{{h}}={4.71}-1.62+1.19× {10}12 {h}-1 {M}⊙ on average, which will likely become present-day halos of mass M h (z = 0) ˜ 2 × 1013 h -1 M ⊙, equivalent to the typical halo mass scale of galaxy groups. We then confirm the decline of the stellar-to-halo mass ratio at M h < 1012 M ⊙, finding M */M h ≈ 5 × 10-3 at M h = 7. 5 × 1011 M ⊙, which is lower by a factor of 2-4 than those measured at higher masses (M h ˜ 1012-13 M ⊙). Finally, we use our results to illustrate the future capabilities of Subaru’s Prime-Focus Spectrograph, a next-generation instrument that will provide strong constraints on the galaxy-formation scenario by obtaining precise measurements of galaxy clustering at z > 1.

Galaxy interactions and star formation: Results of a survey of global H-alpha emission in spiral galaxies in 8 clusters

NASA Technical Reports Server (NTRS)

Moss, C.

1990-01-01

Kennicutt and Kent (1983) have shown that the global H alpha emission from a spiral galaxy is an indicator of the formation rate of massive stars. Moss, Whittle and Irwin (1988) have surveyed two clusters (Abell 347 and 1367) for galaxies with H alpha emission using a high dispersion objective prism technique. The purpose of the survey is to investigate environmental effects on star formation in spiral galaxies, and in particular to ascertain whether star formation is enhanced in cluster spirals. Approximately 20 percent of CGCG galaxies were detected in emission. Two plates of excellent quality were obtained for each of the two clusters, and galaxies were only identified to have emission if this was detected on both plates of a plate pair. In this way, plate flaws and other spurious identifications of emission could be rejected, and weak emission confirmed. The results of this survey have been discussed by Moss (1987). The detected galaxies are of types SO-a and later. The frequency with which galaxies are detected in emission increases towards later morphological type as expected (cf. Kennicutt and Kent 1983). There is no evidence of any dependence of the frequency of detected emission on the absolute magnitude of the galaxy (cf. Moss and Whittle 1990), but there is a strong correlation between a disturbed morphological appearance of the galaxy and the detection of emission. Furthermore it is found that the emission is more centrally concentrated in those galaxies which show a disturbed morphology. It may be noted that the objective prism plate gives a spectrum of a 400 A region around rest wavelength H alpha, but superposed on this is the H alpha emission from the galaxy which, because the light is essentially monochromatic, results in a true two-dimensional image of the H alpha distribution. The visual appearance of the emission on the prism plates was classified according to its diffuseness on a 5 point scale (very diffuse, diffuse, intermediate, compact, and

H I in the Shell Elliptical Galaxy NGC 3656

NASA Astrophysics Data System (ADS)

Balcells, Marc; van Gorkom, J. H.; Sancisi, Renzo; del Burgo, Carlos

2001-10-01

Very Large Array7 neutral hydrogen observations of the shell elliptical galaxy NGC 3656 reveal an edge-on, warped minor-axis gaseous disk (MHI~2×109 Msolar) extending 7 kpc. H I is also found outside the optical image, on two complexes to the northeast and northwest that seem to trace one or two tidal tails, or possibly an outer broken H I disk or ring. These complexes link with the outer edges of the inner disk and appear displaced with respect to the two optical tails in the galaxy. The disk kinematics is strongly lopsided, suggesting recent or ongoing accretion. Integral-field optical fiber spectroscopy at the region of the bright southern shell of NGC 3656 has provided a determination of the stellar velocities of the shell. The shell, at 9 kpc from the center, has traces of H I with velocities bracketing the stellar velocities, providing evidence for a dynamical association of H I and stars at the shell. Within the errors the stars have systemic velocity, suggesting a possible phase-wrapping origin for the shell. We probed a region of 40'×40' (480 kpc×480 kpc)×1160 km s-1 down to an H I mass sensitivity (6 σ) of 3×107 Msolar and detect five dwarf galaxies with H I masses ranging from 2×108 to 2×109 Msolar, all within 180 kpc of NGC 3656 and all within the velocity range (450 km s-1) of the H I of NGC 3656. The dwarfs had been previously cataloged, but none had a known redshift. For the NGC 3656 group to be bound requires a total mass of (3-7.4)×1012 Msolar, yielding a mass-to-light ratio from 125 to 300. The overall H I picture presented by NGC 3656 supports the hypothesis of a disk-disk merger origin or possibly an ongoing process of multiple mergers with nearby dwarfs. Based on observations made with the William Herschel Telescope operated on the island of La Palma by the Isaac Newton Group of Telescopes in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.

Oxygen abundance distributions in six late-type galaxies based on SALT spectra of H II regions

NASA Astrophysics Data System (ADS)

Zinchenko, I. A.; Kniazev, A. Y.; Grebel, E. K.; Pilyugin, L. S.

2015-10-01

Spectra of 34 H ii regions in the late-type galaxies NGC 1087, NGC 2967, NGC 3023, NGC 4030, NGC 4123, and NGC 4517A were observed with the South African Large Telescope (SALT). In all 34 H ii regions, oxygen abundances were determined through the "counterpart" method (C method). Additionally, in two H ii regions in which we detected auroral lines, we measured oxygen abundances with the classic Te method. We also estimated the abundances in our H ii regions using the O3N2 and N2 calibrations and compared those with the C-based abundances. With these data, we examined the radial abundance distributions in the disks of our target galaxies. We derived surface-brightness profiles and other characteristics of the disks (the surface brightness at the disk center and the disk scale length) in three photometric bands for each galaxy using publicly available photometric imaging data. The radial distributions of the oxygen abundances predicted by the relation between abundance and disk surface brightness in the W1 band obtained for spiral galaxies in our previous study are close to the radial distributions of the oxygen abundances determined from the analysis of the emission line spectra for four galaxies where this relation is applicable. Hence, when the surface-brightness profile of a late-type galaxy is known, this parametric relation can be used to estimate the likely present-day oxygen abundance in the disk of the galaxy. Based on observations made with the Southern African Large Telescope, programs 2012-1-RSA_OTH-001, 2012-2-RSA_OTH-003 and 2013-1-RSA_OTH-005.

Complete identification of the Parkes half-Jansky sample of GHz peaked spectrum radio galaxies

NASA Astrophysics Data System (ADS)

de Vries, N.; Snellen, I. A. G.; Schilizzi, R. T.; Lehnert, M. D.; Bremer, M. N.

2007-03-01

Context: Gigahertz Peaked Spectrum (GPS) radio galaxies are generally thought to be the young counterparts of classical extended radio sources. Statistically complete samples of GPS sources are vital for studying the early evolution of radio-loud AGN and the trigger of their nuclear activity. The "Parkes half-Jansky" sample of GPS radio galaxies is such a sample, representing the southern counterpart of the 1998 Stanghellini sample of bright GPS sources. Aims: As a first step of the investigation of the sample, the host galaxies need to be identified and their redshifts determined. Methods: Deep R-band VLT-FORS1 and ESO 3.6 m EFOSC II images and long slit spectra have been taken for the unidentified sources in the sample. Results: We have identified all twelve previously unknown host galaxies of the radio sources in the sample. Eleven have host galaxies in the range 21.0 < RC < 23.0, while one object, PKS J0210+0419, is identified in the near infrared with a galaxy with Ks = 18.3. The redshifts of 21 host galaxies have been determined in the range 0.474 < z < 1.539, bringing the total number of redshifts to 39 (80%). Analysis of the absolute magnitudes of the GPS host galaxies show that at z>1 they are on average a magnitude fainter than classical 3C radio galaxies, as found in earlier studies. However their restframe UV luminosities indicate that there is an extra light contribution from the AGN, or from a population of young stars. Based on observations collected at the European Southern Observatory Very Large Telescope, Paranal, Chile (ESO prog. ID No. 073.B-0289(B)) and the European Southern Observatory 3.6 m Telescope, La Silla, Chile (prog. ID No. 073.B-0289(A)). Appendices are only available in electronic form at http://www.aanda.org

The effects of assembly bias on the inference of matter clustering from galaxy-galaxy lensing and galaxy clustering

NASA Astrophysics Data System (ADS)

McEwen, Joseph E.; Weinberg, David H.

2018-07-01

The combination of galaxy-galaxy lensing and galaxy clustering is a promising route to measuring the amplitude of matter clustering and testing modified gravity theories of cosmic acceleration. Halo occupation distribution (HOD) modelling can extend the approach down to non-linear scales, but galaxy assembly bias could introduce systematic errors by causing the HOD to vary with the large-scale environment at fixed halo mass. We investigate this problem using the mock galaxy catalogs created by Hearin & Watson (2013, HW13), which exhibit significant assembly bias because galaxy luminosity is tied to halo peak circular velocity and galaxy colour is tied to halo formation time. The preferential placement of galaxies (especially red galaxies) in older haloes affects the cutoff of the mean occupation function ⟨Ncen(Mmin)⟩ for central galaxies, with haloes in overdense regions more likely to host galaxies. The effect of assembly bias on the satellite galaxy HOD is minimal. We introduce an extended, environment-dependent HOD (EDHOD) prescription to describe these results and fit galaxy correlation measurements. Crucially, we find that the galaxy-matter cross-correlation coefficient, rgm(r) ≡ ξgm(r) . [ξmm(r)ξgg(r)]-1/2, is insensitive to assembly bias on scales r ≳ 1 h-1 Mpc, even though ξgm(r) and ξgg(r) are both affected individually. We can therefore recover the correct ξmm(r) from the HW13 galaxy-galaxy and galaxy-matter correlations using either a standard HOD or EDHOD fitting method. For Mr ≤ -19 or Mr ≤ -20 samples the recovery of ξmm(r) is accurate to 2 per cent or better. For a sample of red Mr ≤ -20 galaxies, we achieve 2 per cent recovery at r ≳ 2 h-1 Mpc with EDHOD modelling but lower accuracy at smaller scales or with a standard HOD fit. Most of our mock galaxy samples are consistent with rgm = 1 down to r = 1 h-1 Mpc, to within the uncertainties set by our finite simulation volume.

The effects of assembly bias on the inference of matter clustering from galaxy-galaxy lensing and galaxy clustering

NASA Astrophysics Data System (ADS)

McEwen, Joseph E.; Weinberg, David H.

2018-04-01

The combination of galaxy-galaxy lensing (GGL) and galaxy clustering is a promising route to measuring the amplitude of matter clustering and testing modified gravity theories of cosmic acceleration. Halo occupation distribution (HOD) modeling can extend the approach down to nonlinear scales, but galaxy assembly bias could introduce systematic errors by causing the HOD to vary with large scale environment at fixed halo mass. We investigate this problem using the mock galaxy catalogs created by Hearin & Watson (2013, HW13), which exhibit significant assembly bias because galaxy luminosity is tied to halo peak circular velocity and galaxy colour is tied to halo formation time. The preferential placement of galaxies (especially red galaxies) in older halos affects the cutoff of the mean occupation function for central galaxies, with halos in overdense regions more likely to host galaxies. The effect of assembly bias on the satellite galaxy HOD is minimal. We introduce an extended, environment dependent HOD (EDHOD) prescription to describe these results and fit galaxy correlation measurements. Crucially, we find that the galaxy-matter cross-correlation coefficient, rgm(r) ≡ ξgm(r) . [ξmm(r)ξgg(r)]-1/2, is insensitive to assembly bias on scales r ≳ 1 h^{-1} Mpc, even though ξgm(r) and ξgg(r) are both affected individually. We can therefore recover the correct ξmm(r) from the HW13 galaxy-galaxy and galaxy-matter correlations using either a standard HOD or EDHOD fitting method. For Mr ≤ -19 or Mr ≤ -20 samples the recovery of ξmm(r) is accurate to 2% or better. For a sample of red Mr ≤ -20 galaxies we achieve 2% recovery at r ≳ 2 h^{-1} Mpc with EDHOD modeling but lower accuracy at smaller scales or with a standard HOD fit. Most of our mock galaxy samples are consistent with rgm = 1 down to r = 1h-1Mpc, to within the uncertainties set by our finite simulation volume.

Serological comparison of antibodies to avian influenza viruses, subtypes H5N2, H6N1, H7N3 and H7N9 between poultry workers and non-poultry workers in Taiwan in 2012.

PubMed

Huang, S Y; Yang, J R; Lin, Y J; Yang, C H; Cheng, M C; Liu, M T; Wu, H S; Chang, F Y

2015-10-01

In Taiwan, avian influenza virus (AIV) subtypes H5N2, H6N1 and H7N3 have been identified in domestic poultry, and several strains of these subtypes have become endemic in poultry. To evaluate the potential of avian-to-human transmission due to occupational exposure, an exploratory analysis of AIV antibody status in poultry workers was conducted. We enrolled 670 poultry workers, including 335 live poultry vendors (LPVs), 335 poultry farmers (PFs), and 577 non-poultry workers (NPWs). Serum antibody titres against various subtypes of viruses were analysed and compared. The overall seropositivity rates in LPVs and PFs were 2·99% (10/335) and 1·79% (6/335), respectively, against H5N2; and 0·6% (2/335) and 1·19% (4/335), respectively, for H7N3 virus. Of NPWs, 0·35% (2/577) and 0·17% (1/577) were seropositive for H5N2 and H7N3, respectively. Geographical analysis revealed that poultry workers whose workplaces were near locations where H5N2 outbreaks in poultry have been reported face greater risks of being exposed to viruses that result in elevated H5N2 antibody titres. H6N1 antibodies were detected in only one PF, and no H7N9 antibodies were found in the study subjects. Subclinical infections caused by H5N2, H6N1 and H7N3 viruses were thus identified in poultry workers in Taiwan. Occupational exposure is associated with a high risk of AIV infection, and the seroprevalence of particular avian influenza strains in humans reflects the endemic strains in poultry in this region.

GAMA/H-ATLAS: The Local Dust Mass Function and Cosmic Density as a Function of Galaxy Type - A Benchmark for Models of Galaxy Evolution

NASA Astrophysics Data System (ADS)

Beeston, R. A.; Wright, A. H.; Maddox, S.; Gomez, H. L.; Dunne, L.; Driver, S. P.; Robotham, A.; Clark, C. J. R.; Vinsen, K.; Takeuchi, T. T.; Popping, G.; Bourne, N.; Bremer, M. N.; Phillipps, S.; Moffett, A. J.; Baes, M.; Bland-Hawthorn, J.; Brough, S.; De Vis, P.; Eales, S. A.; Holwerda, B. W.; Loveday, J.; Liske, J.; Smith, M. W. L.; Smith, D. J. B.; Valiante, E.; Vlahakis, C.; Wang, L.

2018-06-01

We present the dust mass function (DMF) of 15,750 galaxies with redshift z < 0.1, drawn from the overlapping area of the GAMA and H-ATLAS surveys. The DMF is derived using the density corrected Vmax method, where we estimate Vmax using: (i) the normal photometric selection limit (pVmax) and (ii) a bivariate brightness distribution (BBD) technique, which accounts for two selection effects. We fit the data with a Schechter function, and find M^{*}=(4.65 ± 0.18)× 107 h^2_{70} M_{⊙ }, α = ( - 1.22 ± 0.01), φ ^{*}=(6.26 ± 0.28)× 10^{-3} h^3_{70} Mpc^{-3} dex^{-1}. The resulting dust mass density parameter integrated down to 104 M⊙ is Ωd = (1.11 ± 0.02) × 10-6 which implies the mass fraction of baryons in dust is f_{m_b}=(2.40± 0.04)× 10^{-5}; cosmic variance adds an extra 7-17 per cent uncertainty to the quoted statistical errors. Our measurements have fewer galaxies with high dust mass than predicted by semi-analytic models. This is because the models include too much dust in high stellar mass galaxies. Conversely, our measurements find more galaxies with high dust mass than predicted by hydrodynamical cosmological simulations. This is likely to be from the long timescales for grain growth assumed in the models. We calculate DMFs split by galaxy type and find dust mass densities of Ωd = (0.88 ± 0.03) × 10-6 and Ωd = (0.060 ± 0.005) × 10-6 for late-types and early-types respectively. Comparing to the equivalent galaxy stellar mass functions (GSMF) we find that the DMF for late-types is well matched by the GMSF scaled by (8.07 ± 0.35) × 10-4.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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 increasemore » 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.« less

VizieR Online Data Catalog: Optically red galaxies in H-ATLAS/GAMA (Dariush+, 2016)

NASA Astrophysics Data System (ADS)

Dariush, A.; Dib, S.; Hony, S.; Smith, D. J. B.; Zhukovska, S.; Dunne, L.; Eales, S.; Andrae, E.; Baes, M.; Baldry, I.; Bauer, A.; Bland-Hawthorn, J.; Brough, S.; Bourne, N.; Cava, A.; Clements, D.; Cluver, M.; Cooray, A.; de Zotti, G.; Driver, S.; Grootes, M. W.; Hopkins, A. M.; Hopwood, R.; Kaviraj, S.; Kelvin, L.; Lara-Lopez, M. A.; Liske, J.; Loveday, J.; Maddox, S.; Madore, B.; Michalowski, M. J.; Pearson, C.; Popescu, C.; Robotham, A.; Rowlands, K.; Seibert, M.; Shabani, F.; Smith, M. W. L.; Taylor, E. N.; Tuffs, R.; Valiante, E.; Virdee, J. S.

2016-09-01

We use data from the H-ATLAS phase 1 version 3.0 internal release which contains the IDs of >5σ SPIRE detections at 250um. We define two sub-samples of red and blue galaxies based on NUV-r colours. The morphology of all 117 red galaxies were examined from their SDSS r-band images, following independent visual inspection by three team members. Galaxies were classified into three categories of elliptical (E), spiral (S) and uncertain (U). (2 data files).

Anisotropic Galaxy-Galaxy Lensing in the Illustris-1 Simulation

NASA Astrophysics Data System (ADS)

Brainerd, Tereasa G.

2017-06-01

In Cold Dark Matter universes, the dark matter halos of galaxies are expected to be triaxial, leading to a surface mass density that is not circularly symmetric. In principle, this "flattening" of the dark matter halos of galaxies should be observable as an anisotropy in the weak galaxy-galaxy lensing signal. The degree to which the weak lensing signal is observed to be anisotropic, however, will depend strongly on the degree to which mass (i.e., the dark matter) is aligned with light in the lensing galaxies. That is, the anisotropy will be maximized when the major axis of the projected mass distribution is well aligned with the projected light distribution of the lens galaxies. Observational studies of anisotropic galaxy-galaxy lensing have found an anisotropic weak lensing signal around massive, red galaxies. Detecting the signal around blue, disky galaxies has, however, been more elusive. A possible explanation for this is that mass and light are well aligned within red galaxies and poorly aligned within blue galaxies (an explanation that is supported by studies of the locations of satellites of large, relatively isolated galaxies). Here we compute the weak lensing signal of isolated central galaxies in the Illustris-1 simulation. We compute the anisotropy of the weak lensing signal using two definitions of the geometry: [1] the major axis of the projected dark matter mass distribution and [2] the major axis of the projected stellar mass. On projected scales less than 15% of the virial radius, an anisotropy of order 10% is found for both definitions of the geometry. On larger scales, the anisotropy computed relative to the major axis of the projected light distribution is less than the anisotropy computed relative to the major axis of the projected dark matter. On projected scales of order the virial radius, the anisotropy obtained when using the major axis of the light is an order of magnitude less than the anisotropy obtained when using the major axis of the

H I debris in the IC 1459 galaxy group

NASA Astrophysics Data System (ADS)

Saponara, Juliana; Koribalski, Bärbel S.; Benaglia, Paula; Fernández López, Manuel

2018-01-01

We present H I synthesis imaging of the giant elliptical galaxy IC 1459 and its surroundings with the Australia Telescope Compact Array. Our search for extended H I emission revealed a large complex of H I clouds near IC 1459, likely to be the debris from tidal interactions with neighbouring galaxies. The total H I mass (∼109 M⊙) in the detected clouds spans 250 kpc from the north-east of the gas-rich spiral NGC 7418A to the south-east of IC 1459. The extent and mass of the H I debris, which shows rather irregular morphology and kinematics, are similar to those in other nearby groups. Together with H I clouds recently detected near two other IC 1459 group members, namely IC 5270 and NGC 7418, using phased-array feeds on the Australian Square Kilometre Array Pathfinder, the detected debris make up a significant fraction of the group's intergalactic medium.

Galaxy And Mass Assembly (GAMA): the connection between metals, specific SFR and H I gas in galaxies: the Z-SSFR relation

NASA Astrophysics Data System (ADS)

Lara-López, M. A.; Hopkins, A. M.; López-Sánchez, A. R.; Brough, S.; Colless, M.; Bland-Hawthorn, J.; Driver, S.; Foster, C.; Liske, J.; Loveday, J.; Robotham, A. S. G.; Sharp, R. G.; Steele, O.; Taylor, E. N.

2013-06-01

We study the interplay between gas phase metallicity (Z), specific star formation rate (SSFR) and neutral hydrogen gas (H I) for galaxies of different stellar masses. Our study uses spectroscopic data from Galaxy and Mass Assembly and Sloan Digital Sky Survey (SDSS) star-forming galaxies, as well as H I detection from the Arecibo Legacy Fast Arecibo L-band Feed Array (ALFALFA) and Galex Arecibo SDSS Survey (GASS) public catalogues. We present a model based on the Z-SSFR relation that shows that at a given stellar mass, depending on the amount of gas, galaxies will follow opposite behaviours. Low-mass galaxies with a large amount of gas will show high SSFR and low metallicities, while low-mass galaxies with small amounts of gas will show lower SSFR and high metallicities. In contrast, massive galaxies with a large amount of gas will show moderate SSFR and high metallicities, while massive galaxies with small amounts of gas will show low SSFR and low metallicities. Using ALFALFA and GASS counterparts, we find that the amount of gas is related to those drastic differences in Z and SSFR for galaxies of a similar stellar mass.

EXTENDED NEUTRAL HYDROGEN IN THE ALIGNED SHELL GALAXIES Arp 230 AND MCG -5-7-1: FORMATION OF DISKS IN MERGING GALAXIES?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schiminovich, David; Van Gorkom, J. H.; Van der Hulst, J. M.

2013-02-01

As part of an ongoing study of the neutral hydrogen (H I) morphology and kinematics of 'shell' elliptical galaxies, we present Very Large Array observations of two shell galaxies with aligned shells, Arp 230 and MCG -5-7-1. Our data provide the first H I images of Arp 230 and deeper images of MCG -5-7-1 than previously reported. Optical images of Arp 230 reveal a bright, aligned, interleaved shell system, making it an ideal candidate for 'phase-wrapped' shell formation following a radial encounter with a smaller companion. The fainter, non-interleaved shells of MCG -5-7-1 do not clearly favor a particular formationmore » scenario. The H I we detect in both galaxies extends to nearly the same projected distance as the optical shells. In Arp 230 this gas appears to be anti-correlated with the aligned shells, consistent with our expectations for phase-wrapped shells produced in a radial encounter. In MCG -5-7-1, we observe gas associated with the shells making a 'spatial wrapping' or looping scenario more plausible. Although the extended gas component in both galaxies is unevenly distributed, the gas kinematics are surprisingly regular, looking almost like complete disks in rotation. We use the H I kinematics and optical data to determine mass-to-light ratios M/L{sub B} of 2.4{sup +3.0}{sub -0.5} (at 13.5 kpc, 4.5 R{sub e} ) for Arp 230 and M/L{sub B} of 30 {+-} 7 (at 40 kpc, 7 R{sub e} ) in MCG -5-7-1. In both systems we find that this ratio changes as a function of radius, indicating the presence of a dark halo. By comparing orbital and precession timescales, we conclude that the potentials are slightly flattened. We infer a 5%-10% flattening for Arp 230 and less flattening in the case of MCG -5-7-1. Finally, we present images of the H I associated with the inner disk or (polar) ring of each galaxy and discuss possible explanations for their different present-day star formation rates. We detect total H I masses of 1.1 Multiplication-Sign 10{sup 9} M{sub Sun} in

Radio continuum of galaxies with H2O megamaser disks: 33 GHz VLA data

NASA Astrophysics Data System (ADS)

Kamali, F.; Henkel, C.; Brunthaler, A.; Impellizzeri, C. M. V.; Menten, K. M.; Braatz, J. A.; Greene, J. E.; Reid, M. J.; Condon, J. J.; Lo, K. Y.; Kuo, C. Y.; Litzinger, E.; Kadler, M.

2017-09-01

Context. Galaxies with H2O megamaser disks are active galaxies in whose edge-on accretion disks 22 GHz H2O maser emission has been detected. Because their geometry is known, they provide a unique view into the properties of active galactic nuclei. Aims: The goal of this work is to investigate the nuclear environment of galaxies with H2O maser disks and to relate the maser and host galaxy properties to those of the radio continuum emission of the galaxy. Methods: The 33 GHz (9 mm) radio continuum properties of 24 galaxies with reported 22 GHz H2O maser emission from their disks are studied in the context of the multiwavelength view of these sources. The 29-37 GHz Ka-band observations are made with the Karl Jansky Very Large Array in B, CnB, or BnA configurations, achieving a resolution of 0.2-0.5 arcsec. Hard X-ray data from the Swift/BAT survey and 22 μm infrared data from WISE, 22 GHz H2O maser data and 1.4 GHz data from NVSS and FIRST surveys are also included in the analysis. Results: Eighty-seven percent (21 out of 24) galaxies in our sample show 33 GHz radio continuum emission at levels of 4.5-240σ. Five sources show extended emission (deconvolved source size larger than 2.5 times the major axis of the beam), including one source with two main components and one with three main components. The remaining detected 16 sources (and also some of the above-mentioned targets) exhibit compact cores within the sensitivity limits. Little evidence is found for extended jets (>300 pc) in most sources. Either they do not exist, or our chosen frequency of 33 GHz is too high for a detection of these supposedly steep spectrum features. In NGC 4388, we find an extended jet-like feature that appears to be oriented perpendicular to the H2O megamaser disk. NGC 2273 is another candidate whose radio continuum source might be elongated perpendicular to the maser disk. Smaller 100-300 pc sized jets might also be present, as is suggested by the beam-deconvolved morphology of our

VizieR Online Data Catalog: hCOSMOS: Hectospec survey of galaxies in COSMOS (Damjanov+, 2018)

NASA Astrophysics Data System (ADS)

Damjanov, I.; Zahid, H. J.; Geller, M. J.; Fabricant, D. G.; Hwang, Ho S.

2018-03-01

We target galaxies with r-band magnitudes 17.771 for further details. We observed hCOSMOS galaxies with Hectospec mounted on the 6.5m MMT. The Hectospec spectra cover the wavelength range 3700-9100Å at a resolution of R~1500. We conducted observations during dark and gray nights in 2015 February, 2015 April, 2016 February, and 2016 March. We obtained 5492 science quality spectra (out of which 1405 are duplicates) in varying conditions. We include additional 275 spectra of galaxies in the COSMOS field from the Hectospec data archive. Thus, the hCOSMOS sample includes 4362 unique galaxies. Among these objects, 2661 have a redshift in the zCOSMOS (Lilly+ 2007, J/ApJS/172/70 ; 2009, J/ApJS/184/218) catalog and 1701 redshifts are completely new. For the galaxies that overlap with zCOSMOS, the Hectospec spectra yield a redshift with a smaller error along with broader wavelength coverage. (1 data file).

Galaxy and Mass Assembly (GAMA): small-scale anisotropic galaxy clustering and the pairwise velocity dispersion of galaxies

NASA Astrophysics Data System (ADS)

Loveday, J.; Christodoulou, L.; Norberg, P.; Peacock, J. A.; Baldry, I. K.; Bland-Hawthorn, J.; Brown, M. J. I.; Colless, M.; Driver, S. P.; Holwerda, B. W.; Hopkins, A. M.; Kafle, P. R.; Liske, J.; Lopez-Sanchez, A. R.; Taylor, E. N.

2018-03-01

The galaxy pairwise velocity dispersion (PVD) can provide important tests of non-standard gravity and galaxy formation models. We describe measurements of the PVD of galaxies in the Galaxy and Mass Assembly (GAMA) survey as a function of projected separation and galaxy luminosity. Due to the faint magnitude limit (r < 19.8) and highly complete spectroscopic sampling of the GAMA survey, we are able to reliably measure the PVD to smaller scales (r⊥ = 0.01 h - 1 Mpc) than previous work. The measured PVD at projected separations r⊥ ≲ 1 h - 1 Mpc increases near monotonically with increasing luminosity from σ12 ≈ 200 km s - 1 at Mr = -17 mag to σ12 ≈ 600 km s - 1 at Mr ≈ -22 mag. Analysis of the Gonzalez-Perez et al. (2014) GALFORM semi-analytic model yields no such trend of PVD with luminosity: the model overpredicts the PVD for faint galaxies. This is most likely a result of the model placing too many low-luminosity galaxies in massive haloes.

Dependence of Nebular Heavy-element Abundance on H I Content for Spiral Galaxies

NASA Astrophysics Data System (ADS)

Robertson, Paul; Shields, Gregory A.; Davé, Romeel; Blanc, Guillermo A.; Wright, Audrey

2013-08-01

We analyze the galactic H I content and nebular log (O/H) for 60 spiral galaxies in the Moustakas et al. (2006a) spectral catalog. After correcting for the mass-metallicity relationship, we show that the spirals in cluster environments show a positive correlation for log (O/H) on DEF, the galactic H I deficiency parameter, extending the results of previous analyses of the Virgo and Pegasus I clusters. Additionally, we show for the first time that galaxies in the field obey a similar dependence. The observed relationship between H I deficiency and galactic metallicity resembles similar trends shown by cosmological simulations of galaxy formation including inflows and outflows. These results indicate the previously observed metallicity-DEF correlation has a more universal interpretation than simply a cluster's effects on its member galaxies. Rather, we observe in all environments the stochastic effects of metal-poor infall as minor mergers and accretion help to build giant spirals.

The CO-to-H2 Conversion Factor Within GMCs in Nearby Spiral Galaxies

NASA Astrophysics Data System (ADS)

Donovan Meyer, Jennifer; Koda, J.

2012-01-01

Much of what is known about the evolution of the interstellar medium in spiral galaxies has been learned by analyzing the properties of giant molecular clouds (GMCs). However, these clouds are composed primarily of molecular hydrogen, which is difficult to observe directly since the temperature of the gas in GMCs is too low to excite H2 line emission. As a result, molecular tracers - the most common of which being the lower rotational transitions of the CO molecule - are typically observed instead, requiring a well-calibrated conversion factor between CO flux and H2 mass (Xco). To investigate GMC evolution within galactic disks, I have created high fidelity images of nearby spiral galaxies with a variety of morphologies by combining CO (J=1-0) observations from the Nobeyama 45-meter single dish telescope and the CARMA interferometer in the uv-plane. These images, created as part of the CO Survey of Nearby Galaxies being completed at Stony Brook, utilize the new rms-weighting technique described in Koda et al. (2011). In Donovan Meyer et al. (2011), we deconvolve the CO emission of the nearby spiral galaxy NGC 6946 into the largest sample to date of resolved GMCs in a substantial spiral galaxy other than the Milky Way and derive virial masses and Xco within individual GMCs. Extending this work to three other nearby galaxies from the survey for which we can achieve the most resolved measurements (beam sizes less than 65 pc), we find that the sizes and velocity dispersions of GMCs continue to be largely consistent from galaxy to galaxy. However, while the conversion factor remains within a factor of two compared to the Galactic value, there is an indication that it varies systematically between galaxies.

Featured Image: H I Gas in the Triangulum Galaxy

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2017-08-01

These spectacular images are of M33, otherwise known as the Triangulum Galaxy a spiral galaxy roughly 3 million light-years away. The views on the left and in the center are different Wide-field Infrared Survey Explorer (WISE) filters, and the view on the right is a full-resolution look at the H I gas distribution in M33s inner disk, made with data from the Dominion Radio Astrophysical Observatory (DRAO) Synthesis Telescope and Arecibo. In a new study, a team of authors led by Zacharie Sie Kam (University of Ouagadougou, Burkina Faso; University of Montreal, Canada) uses the H I gas observations to explore how the mass is distributed throughout M33 and how the gas moves as the galaxys disk rotates. To read more about what they learned, check out the paper below.CitationS. Z. Kam et al 2017 AJ 154 41. doi:10.3847/1538-3881/aa79f3

The ACTN3 R577X polymorphism in Russian endurance athletes.

PubMed

Ahmetov, I I; Druzhevskaya, A M; Astratenkova, I V; Popov, D V; Vinogradova, O L; Rogozkin, V A

2010-07-01

The functional 577R allele of the alpha-actinin-3 (ACTN3) gene has been reported to be associated with elite power athlete status, while the nonfunctional 577XX genotype (predicts an alpha-actinin-3 deficient phenotype) has been hypothesised as providing some sort of advantage for endurance athletes. In the present study, the distribution of ACTN3 genotypes and alleles in Russian endurance-oriented athletes were examined and association between ACTN3 genotypes and the competition results of rowers were sought. 456 Russian endurance-oriented athletes of regional or national competitive standard were involved in the study. ACTN3 genotype and allele frequencies were compared with 1211 controls. The data from the Russian Cup Rowing Tournament were used to search for possible association between the ACTN3 genotype and the long-distance (approximately 6 km) rowing results of 54 athletes. DNA was extracted from mouthwash samples. Genotyping for the R577X variant was performed by PCR and restriction enzyme digestion. The frequencies of the ACTN3 577XX genotype (5.7% vs 14.5%; p<0.0001) and 577X allele (33.2% vs 39.0%; p = 0.0025) were significantly lower in endurance-oriented athletes compared with the controls, and none of the highly elite athletes had the 577XX genotype. Furthermore, male rowers with ACTN3 577RR genotype showed better results (1339 (11) s) in long-distance rowing than carriers of 577RX (1386 (12) s) or 577XX (1402 (10) s) genotypes (p = 0.016). Our data show that the ACTN3 577X allele is under-represented in Russian endurance athletes and is associated with the rowers' competition results.

Galaxy bachelors, couples, spouses: Star formation in interacting galaxies

NASA Astrophysics Data System (ADS)

Sun, Jing; Barger, Kathleen; Richstein, Hannah; SDSS-IV/MaNGA

2017-01-01

We investigate the star formation activity in three galaxy systems in different stages of interaction to determine how the environment of galaxies affects their star forming ability and potential. These systems include an isolated galaxy, a pair of interacting galaxies, and a pair of merging galaxies. All of the target galaxies in these systems have similar stellar masses and similar radii and are at similar redshifts. We trace the star formation activity over the past 1-2 Gyr using spatially and kinematically resolved H-alpha emission, H-alpha equivalent width, and 4000-Angstrom break maps. This work is based on data from the fourth-generation Sloan Digital Sky Survey (SDSS-IV)/Mapping Nearby Galaxies at Apache Point Observatory (MaNGA), and is part of the Project No.0285 in SDSS-IV.

H I OBSERVATIONS OF THE Ca II ABSORBING GALAXIES Mrk 1456 AND SDSS J211701.26-002633.7

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cherinka, B.; Schulte-Ladbeck, R. E.; Rosenberg, J. L.

2009-12-15

In an effort to study Damped Ly{alpha} (DLA) galaxies at low redshift, we have been using the Sloan Digital Sky Survey (SDSS) to identify galaxies projected onto quasi-stellar object (QSO) sight lines and to characterize their optical properties. For low-redshift galaxies, the H I 21 cm emission line can be used as an alternate tool for identifying possible DLA galaxies, since H I-emitting galaxies typically exhibit H I columns that are larger than the classical DLA limit. Here, we report on follow-up H I 21 cm emission-line observations of two DLA candidates that are both low-redshift spiral galaxies, Mrk 1456more » and SDSS J211701.26-002633.7. The observations were made using the Green Bank Telescope (GBT) and Arecibo telescope, respectively. Analysis of their H I properties reveal the galaxies to be about one and two M*{sub HI} galaxies, respectively, and to have average H I mass, gas richness, and gas-mass fraction for their morphological types. We consider Mrk 1456 and SDSS J211701.26-002633.7 to be candidate DLA systems based upon the strength of the Ca II absorption lines they cause in their QSO's spectra, and impact parameters to the QSO that are smaller than the stellar disk. Compared to the small numbers of other H I detected DLA and candidate DLA galaxies, Mrk 1456 and SDSS J211701.26-002633.7 have high H I masses. Mrk 1456 and SDSS J211701.26-002633.7 have also been found to lie in galaxy groups that are high in H I gas mass compared to the group containing SBS 1543+593, the only DLA galaxy previously known to be situated in a galaxy group. When compared with the expected properties of low-z DLAs from an H I-detected sample of galaxies, Mrk 1456 and SDSS J211701.26-002633.7 fall within the ranges for impact parameter and M{sub B} ; and the H I mass distribution for the H I-detected DLAs agrees with that of the expected H I mass distribution for low-z DLAs. Our observations support galaxy-evolution models in which high-mass galaxies make up an

Optical/Near-IR spatially resolved study of the H II galaxy Tol 02★

NASA Astrophysics Data System (ADS)

Torres-Campos, A.; Terlevich, E.; Rosa-González, D.; Terlevich, R.; Telles, E.; Díaz, A. I.

2017-11-01

The main goal of this study is to characterize the stellar populations in very low-metallicity galaxies. We have obtained broad U, B, R, I, J, H, K, intermediate Strömgren y and narrow H α and [O III] deep images of the Wolf-Rayet, blue compact dwarf, H II galaxy Tol 02. We have analysed the low surface brightness component, the stellar cluster complexes and the H II regions. The stellar populations in the galaxy have been characterized by comparing the observed broad-band colours with those of single stellar population models. The main results are consistent with Tol 02 being formed by a 1.5 Gyr old disc component at the centre of which a group of eight massive (>104 M⊙) stellar cluster clumps is located. Six of these clumps are 10 Myr old and their near-infrared colours suggest that their light is dominated by Red Supergiant (RSG) stars, the other two are young Wolf-Rayet cluster candidates of ages 3 and 5 Myr, respectively. 12 H II regions in the star-forming region of the galaxy are also identified. These are immersed in a diffuse H α and [O III] emission that spreads towards the north and south covering the old stellar disc. Our spatial-temporal analysis shows that star formation is more likely stochastic and simultaneous within short time-scales. The mismatch between observations and models cannot be attributed alone to a mistreat of the RSG phase and still needs to be further investigated.

Constraining the radio jet proper motion of the high-redshift quasar J2134-0419 at z = 4.3

NASA Astrophysics Data System (ADS)

Perger, Krisztina; Frey, Sándor; Gabányi, Krisztina É.; An, Tao; Britzen, Silke; Cao, Hong-Min; Cseh, Dávid; Dennett-Thorpe, Jane; Gurvits, Leonid I.; Hong, Xiao-Yu; Hook, Isobel M.; Paragi, Zsolt; Schilizzi, Richard T.; Yang, Jun; Zhang, Yingkang

2018-06-01

To date, PMN J2134-0419 (at a redshift z = 4.33) is the second most distant quasar known with a milliarcsecond-scale morphology permitting direct estimates of the jet proper motion. Based on two-epoch observations, we constrained its radio jet proper motion using the very long baseline interferometry (VLBI) technique. The observations were conducted with the European VLBI Network (EVN) at 5 GHz on 1999 November 26 and 2015 October 6. We imaged the central 10-pc scale radio jet emission and modelled its brightness distribution. By identifying a jet component at both epochs separated by 15.86 yr, a proper motion of μ = 0.035 ± 0.023 mas yr-1 is found. It corresponds to an apparent superluminal speed of βa = 4.1 ± 2.7 c. Relativistic beaming at both epochs suggests that the jet viewing angle with respect to the line of sight is smaller than 20°, with a minimum bulk Lorentz factor Γ = 4.3. The small value of the proper motion is in good agreement with the expectations from the cosmological interpretation of the redshift and the current cosmological model. Additionally we analysed archival Very Large Array observations of J2143-0419 and found indication of a bent jet extending to ˜30 kpc.

THE BURSTY STAR FORMATION HISTORIES OF LOW-MASS GALAXIES AT 0.4 < z < 1 REVEALED BY STAR FORMATION RATES MEASURED FROM H β AND FUV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Yicheng; Faber, S. M.; Koo, David C.

2016-12-10

We investigate the burstiness of star formation histories (SFHs) of galaxies at 0.4 <  z  < 1 by using the ratio of star formation rates (SFRs) measured from H β and FUV (1500 Å) (H β -to-FUV ratio). Our sample contains 164 galaxies down to stellar mass ( M {sub *}) of 10{sup 8.5} M {sub ⊙} in the CANDELS GOODS-N region, where Team Keck Redshift Survey Keck/DEIMOS spectroscopy and Hubble Space Telescope /WFC3 F275W images from CANDELS and Hubble Deep UV Legacy Survey are available. When the ratio of H β - and FUV-derived SFRs is measured, dust extinction correction ismore » negligible (except for very dusty galaxies) with the Calzetti attenuation curve. The H β -to-FUV ratio of our sample increases with M {sub *} and SFR. The median ratio is ∼0.7 at M {sub *} ∼ 10{sup 8.5} M {sub ⊙} (or SFR ∼ 0.5 M {sub ⊙} yr{sup −1}) and increases to ∼1 at M {sub *} ∼ 10{sup 10} M {sub ⊙} (or SFR ∼ 10 M {sub ⊙} yr{sup −1}). At M {sub *} < 10{sup 9.5} M {sub ⊙}, our median H β -to-FUV ratio is lower than that of local galaxies at the same M {sub *}, implying a redshift evolution. Bursty SFH on a timescale of a few tens of megayears on galactic scales provides a plausible explanation for our results, and the importance of the burstiness increases as M {sub *} decreases. Due to sample selection effects, our H β -to-FUV ratio may be an upper limit of the true value of a complete sample, which strengthens our conclusions. Other models, e.g., non-universal initial mass function or stochastic star formation on star cluster scales, are unable to plausibly explain our results.« less

Emission line galaxy pairs up to z=1.5 from the WISP survey

NASA Astrophysics Data System (ADS)

Teplitz, Harry I.; Dai, Yu Sophia; Malkan, Matthew Arnold; Scarlata, Claudia; Colbert, James W.; Atek, Hakim; Bagley, Micaela B.; Baronchelli, Ivano; Bedregal, Alejandro; Beck, Melanie; Bunker, Andrew; Dominguez, Alberto; Hathi, Nimish P.; Henry, Alaina L.; Mehta, Vihang; Pahl, Anthony; Rafelski, Marc; Ross, Nathaniel; Rutkowski, Michael J.; Siana, Brian D.; WISPs Team

2016-01-01

We present a sample of spectroscopically identified emission line galaxy pairs up to z=1.5 from WISPs (WFC3 Infrared Spectroscopic Parallel survey) using high resolution direct and grism images from HST. We searched ~150 fields with a covered area of ~600 arcmin^2, and a comoving volume of > 400 Gpc^3 at z=1-2, and found ~80 very close physical pairs (projected separation Dp < 50 h^{-1}kpc, relative velocity d_v < 500 kms^{-1}), and ~100 close physical pairs (50 < Dp < 100 h^{-1}kpc, d_v < 1000 kms^{-1}) of emission line galaxies, including two dozen triplets and quadruples. In this poster we present the multi-wavelength data, star formation rate (SFR), mass ratio, and study the merger rate evolution with this special galaxy pair sample.

The origin of the X-ray, radio and H I structures in the NGC 5903 galaxy group

NASA Astrophysics Data System (ADS)

O'Sullivan, Ewan; Kolokythas, Konstantinos; Kantharia, Nimisha G.; Raychaudhury, Somak; David, Laurence P.; Vrtilek, Jan M.

2018-02-01

The NGC 5903 galaxy group is a nearby (∼30 Mpc) system of ∼30 members, dominated by the giant ellipticals NGC 5903 and NGC 5898. The group contains two unusual structures: a ∼110 kpc long H I filament crossing NGC 5903 and a ∼75 kpc wide diffuse, steep-spectrum radio source of unknown origin that overlaps NGC 5903 and appears to be partly enclosed by the H I filament. Using a combination of Chandra, XMM-Newton, Giant Meterwave Radio Telescope (GMRT) and Very Large Array (VLA) observations, we detect a previously unknown ∼0.65 keV intra-group medium filling the volume within 145 kpc of NGC 5903 and find a loop of enhanced X-ray emission extending ∼35 kpc south-west from the galaxy, enclosing the brightest part of the radio source. The northern and eastern parts of this X-ray structure are also strongly correlated with the southern parts of the H I filament. We determine the spectral index of the bright radio emission to be α _{150}^{612} = 1.03 ± 0.08, indicating a radiative age >360 Myr. We discuss the origin of the correlated radio, X-ray and H I structures, either through an interaction-triggered active galactic nucleus (AGN) outburst with enthalpy 1.8 × 1057 erg, or via a high-velocity collision between a galaxy and the H I filament. While neither scenario provides a complete explanation, we find that an AGN outburst is the most likely source of the principal X-ray and radio structures. However, it is clear that galaxy interactions continue to play an important role in the development of this relatively highly evolved galaxy group. We also resolve the question of whether the group member galaxy ESO 514-3 hosts a double-lobed radio source, confirming that the source is a superposed background AGN.

Collimation, Acceleration, and Recollimation Shock in the Jet of Gamma-Ray Emitting Radio-loud Narrow-line Seyfert 1 Galaxy 1H0323+342

NASA Astrophysics Data System (ADS)

Hada, Kazuhiro; Doi, Akihiro; Wajima, Kiyoaki; D’Ammando, Filippo; Orienti, Monica; Giroletti, Marcello; Giovannini, Gabriele; Nakamura, Masanori; Asada, Keiichi

2018-06-01

We investigated the detailed radio structure of the jet of 1H 0323+342 using high-resolution multifrequency Very Long Baseline Array observations. This source is known as the nearest γ-ray emitting radio-loud narrow-line Seyfert 1 (NLS1) galaxy. We discovered that the morphology of the inner jet is well characterized by a parabolic shape, indicating that the jet is continuously collimated near the jet base. On the other hand, we found that the jet expands more rapidly at larger scales, resulting in a conical shape. The location of the “collimation break” is coincident with a bright quasi-stationary feature at 7 mas from core (corresponding to a deprojected distance on the order of ∼100 pc), where the jet width locally contracts together with highly polarized signals, suggesting a recollimation shock. We found that the collimation region is coincident with the region where the jet speed gradually accelerates, suggesting a coexistence of the jet acceleration and collimation zone, ending up with the recollimation shock, which could be a potential site of high-energy γ-ray flares detected by the Fermi-LAT. Remarkably, these observational features of the 1H 0323+342 jet are overall very similar to those of the nearby radio galaxy M87 and HST-1 as well as some blazars, suggesting that a common jet formation mechanism might be at work. Based on the similarity of the jet profile of the two sources, we also briefly discuss the mass of the central black hole of 1H 0323+342, which is also still highly controversial in this source and NLS1s in general.

Tests of star formation metrics in the low-metallicity galaxy NGC 5253 using ALMA observations of H30α line emission

NASA Astrophysics Data System (ADS)

Bendo, G. J.; Miura, R. E.; Espada, D.; Nakanishi, K.; Beswick, R. J.; D'Cruze, M. J.; Dickinson, C.; Fuller, G. A.

2017-11-01

We use Atacama Large Millimeter/submillimeter Array (ALMA) observations of H30α (231.90 GHz) emission from the low-metallicity dwarf galaxy NGC 5253 to measure the star formation rate (SFR) within the galaxy and to test the reliability of SFRs derived from other commonly used metrics. The H30α emission, which originates mainly from the central starburst, yields a photoionizing photon production rate of (1.9 ± 0.3) × 1052 s-1 and an SFR of 0.087 ± 0.013 M⊙ yr-1 based on conversions that account for the low metallicity of the galaxy and for stellar rotation. Among the other star formation metrics we examined, the SFR calculated from the total infrared flux was statistically equivalent to the values from the H30α data. The SFR based on a previously published version of the H α flux that was extinction corrected using Paα and Paβ lines was lower than but also statistically similar to the H30α value. The mid-infrared (22 μm) flux density and the composite star formation tracer based on H α and mid-infrared emission give SFRs that were significantly higher because the dust emission appears unusually hot compared to typical spiral galaxies. Conversely, the 70 and 160 μm flux densities yielded SFRs lower than the H30α value, although the SFRs from the 70 μm and H30α data were within 1σ-2σ of each other. While further analysis on a broader range of galaxies is needed, these results are instructive of the best and worst methods to use when measuring SFR in low-metallicity dwarf galaxies like NGC 5253.

Molecular gas in low-metallicity starburst galaxies:. Scaling relations and the CO-to-H2 conversion factor

NASA Astrophysics Data System (ADS)

Amorín, R.; Muñoz-Tuñón, C.; Aguerri, J. A. L.; Planesas, P.

2016-04-01

Context. Tracing the molecular gas-phase in low-mass star-forming galaxies becomes extremely challenging due to significant UV photo-dissociation of CO molecules in their low-dust, low-metallicity ISM environments. Aims: We aim to study the molecular content and the star-formation efficiency of a representative sample of 21 blue compact dwarf galaxies (BCDs), previously characterized on the basis of their spectrophotometric properties. Methods: We present CO (1-0) and (2-1) observations conducted at the IRAM-30m telescope. These data are further supplemented with additional CO measurements and multiwavelength ancillary data from the literature. We explore correlations between the derived CO luminosities and several galaxy-averaged properties. Results: We detect CO emission in seven out of ten BCDs observed. For two galaxies these are the first CO detections reported so far. We find the molecular content traced by CO to be correlated with the stellar and Hi masses, star formation rate (SFR) tracers, the projected size of the starburst, and its gas-phase metallicity. BCDs appear to be systematically offset from the Schmidt-Kennicutt (SK) law, showing lower average gas surface densities for a given ΣSFR, and therefore showing extremely low (≲0.1 Gyr) H2 and H2 +Hi depletion timescales. The departure from the SK law is smaller when considering H2 +Hi rather than H2 only, and is larger for BCDs with lower metallicity and higher specific SFR. Thus, the molecular fraction (ΣH2/ ΣHI) and CO depletion timescale (ΣH2/ ΣSFR) of BCDs is found to be strongly correlated with metallicity. Using this, and assuming that the empirical correlation found between the specific SFR and galaxy-averaged H2 depletion timescale of more metal-rich galaxies extends to lower masses, we derive a metallicity-dependent CO-to-H2 conversion factor αCO,Z ∝ (Z/Z⊙)- y, with y = 1.5(±0.3)in qualitative agreement with previous determinations, dust-based measurements, and recent model

Dust Attenuation and H(alpha) Star Formation Rates of Z Approx. 0.5 Galaxies

NASA Technical Reports Server (NTRS)

Ly, Chun; Malkan, Matthew A.; Kashikawa, Nobunari; Ota, Kazuaki; Shimasaku, Kazuhiro; Iye, Masanori; Currie, Thayne

2012-01-01

Using deep narrow-band and broad-band imaging, we identify 401 z approximately 0.40 and 249 z approximately 0.49 H-alpha line-emitting galaxies in the Subaru Deep Field. Compared to other H-alpha surveys at similar redshifts, our samples are unique since they probe lower H-alpha luminosities, are augmented with multi-wavelength (rest-frame 1000AA--1.5 microns) coverage, and a large fraction (20%) of our samples has already been spectroscopically confirmed. Our spectra allow us to measure the Balmer decrement for nearly 60 galaxies with H-beta detected above 5-sigma. The Balmer decrements indicate an average extinction of A(H-alpha)=0.7(uparrow){+1.4}_{-0.7} mag. We find that the Balmer decrement systematically increases with higher H-alpha luminosities and with larger stellar masses, in agreement with previous studies with sparser samples. We find that the SFRs estimated from modeling the spectral energy distribution (SED) is reliable---we derived an "intrinsic" H-alpha luminosity which is then reddened assuming the color excess from SED modeling. The SED-predicted H-alpha luminosity agrees with H-alpha narrow-band measurements over 3 dex (rms of 0.25 dex). We then use the SED SFRs to test different statistically-based dust corrections for H-alpha and find that adopting one magnitude of extinction is inappropriate: galaxies with lower luminosities are less reddened. We find that the luminosity-dependent dust correction of Hopkins et al. yields consistent results over 3 dex (rms of 0.3 dex). Our comparisons are only possible by assuming that stellar reddening is roughly half of nebular reddening. The strong correspondence argue that with SED modeling, we can derive reliable intrinsic SFRs even in the absence of H-alpha measurements at z approximately 0.5.

Velocity dispersions in galaxies: 1: The SO galaxy NGC 7332

NASA Technical Reports Server (NTRS)

Morton, D. C.; Chevalier, R. A.

1971-01-01

A Coude spectrum of the SO galaxy NGC 7332 with 0.9 A resolution from 4186 to 4364 A was obtained with the SEC vidicon television camera and the Hale telescope. Comparisons with spectra of G and K giant stars, numerically broadened for various Maxwellian velocity distributions, give a dispersion velocity in the line of sight of 160 + or - 20 km/sec with the best fit at G8III. The dispersion appears to be constant within + or - 35 km/sec out to 1.4 kpc (H = 100 km/sec/mpc). After correction for projection, the rotation curve has a slope of 0.16 km/sec/pc at the center and a velocity of 130 km/sec at 1.4 kpc where it is still increasing. For an estimated effective radius of 3.5 kpc enclosing half the light, the virial theorem gives a mass of 1.4 x 10 to the 11th power solar masses if the mass-to-light ratio is constant throughout the galaxy. The photographic luminosity is 8.3 x 10 to the 9th power solar luminosities so that the M/L ratio is 17.

Galaxy Clustering Around Nearby Luminous Quasars

NASA Technical Reports Server (NTRS)

Fisher, Karl B.; Bahcall, John N.; Kirhakos, Sofia; Schneider, Donald P.

1996-01-01

We examine the clustering of galaxies around a sample of 20 luminous low redshift (z approx. less than 0.30) quasars observed with the Wide Field Camera-2 on the Hubble Space Telescope (HST). The HST resolution makes possible galaxy identification brighter than V = 24.5 and as close as 1 min or 2 min to the quasar. We find a significant enhancement of galaxies within a projected separation of approx. less than 100 1/h kpc of the quasars. If we model the QSO/galaxy correlation function as a power law with a slope given by the galaxy/galaxy correlation function, we find that the ratio of the QSO/galaxy to galaxy/galaxy correlation functions is 3.8 +/- 0.8. The galaxy counts within r less than 15 1/h kpc of the quasars are too high for the density profile to have an appreciable core radius (approx. greater than 100 1/h kpc). Our results reinforce the idea that low redshift quasars are located preferentially in groups of 10-20 galaxies rather than in rich clusters. We see no significant difference in the clustering amplitudes derived from radio-loud and radio-quiet subsamples.

Isolated galaxies, pairs, and groups of galaxies

NASA Technical Reports Server (NTRS)

Kuneva, I.; Kalinkov, M.

1990-01-01

The authors searched for isolated galaxies, pairs and groups of galaxies in the CfA survey (Huchra et al. 1983). It was assumed that the distances to galaxies are given by R = V/H sub o, where H sub o = 100 km s(exp -1) Mpc(exp -1) and R greater than 6 Mpc. The searching procedure is close to those, applied to find superclusters of galaxies (Kalinkov and Kuneva 1985, 1986). A sphere with fixed radius r (asterisk) is described around each galaxy. The mean spatial density in the sphere is m. Let G (sup 1) be any galaxy and G (sup 2) be its nearest neighbor at a distance R sub 2. If R sub 2 exceeds the 95 percent quintile in the distribution of the distances of the second neighbors, then G (sup 1) is an isolated galaxy. Let the midpoint of G (sup 1) and G (sup 2) be O sub 2 and r sub 2=R sub 2/2. For the volume V sub 2, defined with the radius r sub 2, the density D sub 2 less than k mu, the galaxy G (sup 2) is a single one and the procedure for searching for pairs and groups, beginning with this object is over and we have to pass to another object. Here the authors present the groups - isolated and nonisolated - with n greater than 3, found in the CfA survey in the Northern galactic hemisphere. The parameters used are k = 10 and r (asterisk) = 5 Mpc. Table 1 contains: (1) the group number, (2) the galaxy, nearest to the multiplet center, (3) multiplicity n, (4) the brightest galaxy if it is not listed in (2); (5) and (6) are R.A. and Dec. (1950), (7) - mean distance D in Mpc. Further there are the mean density rho (8) of the multiplet (galaxies Mpc (exp -3), (9) the density rho (asterisk) for r (asterisk) = 5 Mpc and (10) the density rho sub g for the group with its nearest neighbor. The parenthesized digits for densities in the last three columns are powers of ten.

THE CLUSTERING OF ALFALFA GALAXIES: DEPENDENCE ON H I MASS, RELATIONSHIP WITH OPTICAL SAMPLES, AND CLUES OF HOST HALO PROPERTIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Papastergis, Emmanouil; Giovanelli, Riccardo; Haynes, Martha P.

We use a sample of ≈6000 galaxies detected by the Arecibo Legacy Fast ALFA (ALFALFA) 21 cm survey to measure the clustering properties of H I-selected galaxies. We find no convincing evidence for a dependence of clustering on galactic atomic hydrogen (H I) mass, over the range M{sub H{sub I}} ≈ 10{sup 8.5}-10{sup 10.5} M{sub ☉}. We show that previously reported results of weaker clustering for low H I mass galaxies are probably due to finite-volume effects. In addition, we compare the clustering of ALFALFA galaxies with optically selected samples drawn from the Sloan Digital Sky Survey (SDSS). We findmore » that H I-selected galaxies cluster more weakly than even relatively optically faint galaxies, when no color selection is applied. Conversely, when SDSS galaxies are split based on their color, we find that the correlation function of blue optical galaxies is practically indistinguishable from that of H I-selected galaxies. At the same time, SDSS galaxies with red colors are found to cluster significantly more than H I-selected galaxies, a fact that is evident in both the projected as well as the full two-dimensional correlation function. A cross-correlation analysis further reveals that gas-rich galaxies 'avoid' being located within ≈3 Mpc of optical galaxies with red colors. Next, we consider the clustering properties of halo samples selected from the Bolshoi ΛCDM simulation. A comparison with the clustering of ALFALFA galaxies suggests that galactic H I mass is not tightly related to host halo mass and that a sizable fraction of subhalos do not host H I galaxies. Lastly, we find that we can recover fairly well the correlation function of H I galaxies by just excluding halos with low spin parameter. This finding lends support to the hypothesis that halo spin plays a key role in determining the gas content of galaxies.« less

25 CFR 162.577 - How will BIA decide whether to approve an assignment of a WSR lease?

Code of Federal Regulations, 2013 CFR

2013-04-01

... 25 Indians 1 2013-04-01 2013-04-01 false How will BIA decide whether to approve an assignment of a WSR lease? 162.577 Section 162.577 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR LAND AND WATER LEASES AND PERMITS Wind and Solar Resource Leases Wsr Lease Assignments § 162.577 How will...

25 CFR 162.577 - How will BIA decide whether to approve an assignment of a WSR lease?

Code of Federal Regulations, 2014 CFR

2014-04-01

... 25 Indians 1 2014-04-01 2014-04-01 false How will BIA decide whether to approve an assignment of a WSR lease? 162.577 Section 162.577 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR LAND AND WATER LEASES AND PERMITS Wind and Solar Resource Leases Wsr Lease Assignments § 162.577 How will...

Cosmological parameter constraints from galaxy-galaxy lensing and galaxy clustering with the SDSS DR7

NASA Astrophysics Data System (ADS)

Mandelbaum, Rachel; Slosar, Anže; Baldauf, Tobias; Seljak, Uroš; Hirata, Christopher M.; Nakajima, Reiko; Reyes, Reinabelle; Smith, Robert E.

2013-06-01

Recent studies have shown that the cross-correlation coefficient between galaxies and dark matter is very close to unity on scales outside a few virial radii of galaxy haloes, independent of the details of how galaxies populate dark matter haloes. This finding makes it possible to determine the dark matter clustering from measurements of galaxy-galaxy weak lensing and galaxy clustering. We present new cosmological parameter constraints based on large-scale measurements of spectroscopic galaxy samples from the Sloan Digital Sky Survey (SDSS) data release 7. We generalize the approach of Baldauf et al. to remove small-scale information (below 2 and 4 h-1 Mpc for lensing and clustering measurements, respectively), where the cross-correlation coefficient differs from unity. We derive constraints for three galaxy samples covering 7131 deg2, containing 69 150, 62 150 and 35 088 galaxies with mean redshifts of 0.11, 0.28 and 0.40. We clearly detect scale-dependent galaxy bias for the more luminous galaxy samples, at a level consistent with theoretical expectations. When we vary both σ8 and Ωm (and marginalize over non-linear galaxy bias) in a flat Λ cold dark matter model, the best-constrained quantity is σ8(Ωm/0.25)0.57 = 0.80 ± 0.05 (1σ, stat. + sys.), where statistical and systematic errors (photometric redshift and shear calibration) have comparable contributions, and we have fixed ns = 0.96 and h = 0.7. These strong constraints on the matter clustering suggest that this method is competitive with cosmic shear in current data, while having very complementary and in some ways less serious systematics. We therefore expect that this method will play a prominent role in future weak lensing surveys. When we combine these data with Wilkinson Microwave Anisotropy Probe 7-year (WMAP7) cosmic microwave background (CMB) data, constraints on σ8, Ωm, H0, wde and ∑mν become 30-80 per cent tighter than with CMB data alone, since our data break several parameter

1E 0104.2 + 3153 - A broad absorption-line QSO viewed through a giant elliptical galaxy

NASA Technical Reports Server (NTRS)

Stocke, J. T.; Liebert, J.; Schild, R.; Gioia, I. M.; Maccacaro, T.

1984-01-01

The optical identification of the X-ray source 1E 0104.2 + 3153 is complicated by the close projection of a broad absorption-line (BAL) QSO (z = 2.027) 10 arcsec from a giant elliptical galaxy (z = 0.111) at the center of a compact group of galaxies. At only 1.2 de Vaucouleur radii (16 kpc for H sub 0 = 100 km/s Mpc) this QSO-galaxy projection is the closest yet discovered. Based upon current observations, the source of the X-ray emission cannot be conclusively determined. Present in the BAL QSO spectrum are extremely strong Ca II H and K absorption lines due to the intervening galaxy, the first optical detection of the cold interstellar medium in an elliptical galaxy. The strength of these lines (EW = 2 and 1 A) requires observation through several interstellar clouds in the line of sight to the QSO. By its proximity to the central regions of the elliptical galaxy and the relative distances of the galaxy and QSO, this QSO is a particularly good candidate for observing dramatic transient gravitational lensing phenomena due to halo stars in the foreground galaxy.

Galaxies clustering around QSOs with z = 0.9-1.5 and the origin of blue field galaxies

NASA Technical Reports Server (NTRS)

Hintzen, Paul; Romanishin, W.; Valdes, Francisco

1991-01-01

Deep CCD images were obtained in Mould-Cousins R and I passbands of 16 radio quasars with z values between 0.9 and 1.5 and absolute values of b above 35 deg, chosen from the Veron-Cetty and Veron (1984) catalog. Results indicate that, in this population of radio quasars, there is a statistically significant excess of galaxies within 15 arcsec of the quasars and brighter than R = 23 and I = 22. However, contrary to the report of Tyson (1986), no excess was found of galaxies with R less than 21 lying within 30 arcsec of quasars in this redshift range. Data were also obtained for very blue galaxies seen among objects in the general field, all of which are bluer in R-I than Magellanic irregulars at any redshift less than 3. It is suggested that this population might be comprised of low-redshift low-luminosity (H II region) galaxies of the type studied by French (1980) and/or higher redshift galaxies with strong cooling flows and forbidden O II lines.

Optical Variability of Narrow-line and Broad-line Seyfert 1 Galaxies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rakshit, Suvendu; Stalin, C. S., E-mail: suvenduat@gmail.com

We studied the optical variability (OV) of a large sample of narrow-line Seyfert 1 (NLSy1) and broad-line Seyfert 1 (BLSy1) galaxies with z < 0.8 to investigate any differences in their OV properties. Using archival optical V -band light curves from the Catalina Real Time Transient Survey that span 5–9 years and modeling them using damped random walk, we estimated the amplitude of variability. We found that NLSy1 galaxies as a class show lower amplitude of variability than their broad-line counterparts. In the sample of both NLSy1 and BLSy1 galaxies, radio-loud sources are found to have higher variability amplitude thanmore » radio-quiet sources. Considering only sources that are detected in the X-ray band, NLSy1 galaxies are less optically variable than BLSy1 galaxies. The amplitude of variability in the sample of both NLSy1 and BLSy1 galaxies is found to be anti-correlated with Fe ii strength but correlated with the width of the H β line. The well-known anti-correlation of variability–luminosity and the variability–Eddington ratio is present in our data. Among the radio-loud sample, variability amplitude is found to be correlated with radio-loudness and radio-power, suggesting that jets also play an important role in the OV in radio-loud objects, in addition to the Eddington ratio, which is the main driving factor of OV in radio-quiet sources.« less

Properties of Narrow line Seyfert 1 galaxies

NASA Astrophysics Data System (ADS)

Rakshit, Suvendu; Stalin, Chelliah Subramonian; Chand, Hum; Zhang, Xue-Guang

2018-04-01

Narrow line Seyfert 1 (NLSy1) galaxies constitute a class of active galactic nuclei characterized by the full width at half maximum (FWHM) of the Hα broad emission line <2000 km s-1 and the flux ratio of [O III] to Hα <3. Their properties are not well understood since only a few NLSy1 galaxies were known earlier. We have studied various properties of NLSy1 galaxies using an enlarged sample and compared them with the conventional broad-line Seyfert 1 (BLSy1) galaxies. Both the sample of sources have z˜ 0.8 and their optical spectra from SDSS-DR12 that are used to derive various physical parameters have a median signal to noise (S/N) ratio >10 pixel-1. A strong correlation between the Hα and Hα emission lines is found both in the FWHM and flux. The nuclear continuum luminosity is found to be strongly correlated with the luminosity of Hα, Hα and [O III] emission lines. The black hole mass in NLSy1 galaxies is lower compared to their broad line counterparts. Compared to BLSy1 galaxies, NLSy1 galaxies have a stronger FeII emission and a higher Eddington ratio that place them in the extreme upper right corner of the R4570 - λEdd diagram. The distribution of the radio-loudness parameter (R) in NLSy1 galaxies drops rapidly at R>10 compared to the BLSy1 galaxies that have powerful radio jets. The soft X-ray photon index in NLSy1 galaxies is on average higher (2.9 ± 0.9) than BLSy1 galaxies (2.4 ± 0.8). It is anti-correlated with the Hα width but correlated with the FeII strength. NLSy1 galaxies on average have a lower amplitude of optical variability compared to their broad lines counterparts. These results suggest Eddington ratio as the main parameter that drives optical variability in these sources.

Radio properties of type 1.8 and 1.9 Seyfert galaxies

NASA Technical Reports Server (NTRS)

Ulvestad, James S.

1986-01-01

A number of type 1.8 and 1.9 Seyfert galaxies have been observed at the VLA in order to compare their properties with those of the other types of Seyfert galaxy. The observed types have radio luminosities in the range of 10 to the 39th-40.5th args/s, with the median near 10 to the 40th ergs/s. Most of these galaxies have radio sources with diameters of about 500 pc or less. The ratio of radio luminosity to featureless optical continuum luminosity in the Seyfert 1.8/12.9 galaxies and Seyfert 1.2/1.5 galaxies is intermediate between the values for Seyfert 1 and Seyfert 2 galaxies. The infrared-to-radio ratio decreases along the sequence from Seyfert 1 galaxies, through intermediate Seyfert galaxies, to Seyfert 2 galaxies. This systematic statistical difference in the ratio of two aspect-independent quantities implies that the differences among the Seyfert classes cannot be attributed solely to differences in viewing angle.

PRIMUS: Galaxy Clustering as a Function of Luminosity and Color at 0.2 < z < 1

NASA Astrophysics Data System (ADS)

Skibba, Ramin A.; Smith, M. Stephen M.; Coil, Alison L.; Moustakas, John; Aird, James; Blanton, Michael R.; Bray, Aaron D.; Cool, Richard J.; Eisenstein, Daniel J.; Mendez, Alexander J.; Wong, Kenneth C.; Zhu, Guangtun

2014-04-01

We present measurements of the luminosity and color-dependence of galaxy clustering at 0.2 < z < 1.0 in the Prism Multi-object Survey. We quantify the clustering with the redshift-space and projected two-point correlation functions, ξ(rp , π) and wp (rp ), using volume-limited samples constructed from a parent sample of over ~130, 000 galaxies with robust redshifts in seven independent fields covering 9 deg2 of sky. We quantify how the scale-dependent clustering amplitude increases with increasing luminosity and redder color, with relatively small errors over large volumes. We find that red galaxies have stronger small-scale (0.1 Mpc h -1 < rp < 1 Mpc h -1) clustering and steeper correlation functions compared to blue galaxies, as well as a strong color dependent clustering within the red sequence alone. We interpret our measured clustering trends in terms of galaxy bias and obtain values of b gal ≈ 0.9-2.5, quantifying how galaxies are biased tracers of dark matter depending on their luminosity and color. We also interpret the color dependence with mock catalogs, and find that the clustering of blue galaxies is nearly constant with color, while redder galaxies have stronger clustering in the one-halo term due to a higher satellite galaxy fraction. In addition, we measure the evolution of the clustering strength and bias, and we do not detect statistically significant departures from passive evolution. We argue that the luminosity- and color-environment (or halo mass) relations of galaxies have not significantly evolved since z ~ 1. Finally, using jackknife subsampling methods, we find that sampling fluctuations are important and that the COSMOS field is generally an outlier, due to having more overdense structures than other fields; we find that "cosmic variance" can be a significant source of uncertainty for high-redshift clustering measurements.

Early-type galaxies have been the predominant morphological class for massive galaxies since only z ˜ 1

NASA Astrophysics Data System (ADS)

Buitrago, Fernando; Trujillo, Ignacio; Conselice, Christopher J.; Häußler, Boris

2013-01-01

Present-day massive galaxies are composed mostly of early-type objects. It is unknown whether this was also the case at higher redshifts. In a hierarchical assembling scenario the morphological content of the massive population is expected to change with time from disc-like objects in the early Universe to spheroid-like galaxies at present. In this paper we have probed this theoretical expectation by compiling a large sample of massive (Mstellar ≥ 1011 h- 270 M⊙) galaxies in the redshift interval 0 < z < 3. Our sample of 1082 objects comprises 207 local galaxies selected from Sloan Digital Sky Survey plus 875 objects observed with the Hubble Space Telescope belonging to the Palomar Observatory Wide-field InfraRed/DEEP2 and GOODS NICMOS Survey surveys. 639 of our objects have spectroscopic redshifts. Our morphological classification is performed as close as possible to the optical rest frame according to the photometric bands available in our observations both quantitatively (using the Sérsic index as a morphological proxy) and qualitatively (by visual inspection). Using both techniques we find an enormous change on the dominant morphological class with cosmic time. The fraction of early-type galaxies among the massive galaxy population has changed from ˜20-30 per cent at z ˜ 3 to ˜70 per cent at z = 0. Early-type galaxies have been the predominant morphological class for massive galaxies since only z ˜ 1.

nIFTY galaxy cluster simulations - III. The similarity and diversity of galaxies and subhaloes

NASA Astrophysics Data System (ADS)

Elahi, Pascal J.; Knebe, Alexander; Pearce, Frazer R.; Power, Chris; Yepes, Gustavo; Cui, Weiguang; Cunnama, Daniel; Kay, Scott T.; Sembolini, Federico; Beck, Alexander M.; Davé, Romeel; February, Sean; Huang, Shuiyao; Katz, Neal; McCarthy, Ian G.; Murante, Giuseppe; Perret, Valentin; Puchwein, Ewald; Saro, Alexandro; Teyssier, Romain

2016-05-01

We examine subhaloes and galaxies residing in a simulated Λ cold dark matter galaxy cluster (M^crit_{200}=1.1× 10^{15} h^{-1} M_{⊙}) produced by hydrodynamical codes ranging from classic smooth particle hydrodynamics (SPH), newer SPH codes, adaptive and moving mesh codes. These codes use subgrid models to capture galaxy formation physics. We compare how well these codes reproduce the same subhaloes/galaxies in gravity-only, non-radiative hydrodynamics and full feedback physics runs by looking at the overall subhalo/galaxy distribution and on an individual object basis. We find that the subhalo population is reproduced to within ≲10 per cent for both dark matter only and non-radiative runs, with individual objects showing code-to-code scatter of ≲0.1 dex, although the gas in non-radiative simulations shows significant scatter. Including feedback physics significantly increases the diversity. Subhalo mass and Vmax distributions vary by ≈20 per cent. The galaxy populations also show striking code-to-code variations. Although the Tully-Fisher relation is similar in almost all codes, the number of galaxies with 109 h- 1 M⊙ ≲ M* ≲ 1012 h- 1 M⊙ can differ by a factor of 4. Individual galaxies show code-to-code scatter of ˜0.5 dex in stellar mass. Moreover, systematic differences exist, with some codes producing galaxies 70 per cent smaller than others. The diversity partially arises from the inclusion/absence of active galactic nucleus feedback. Our results combined with our companion papers demonstrate that subgrid physics is not just subject to fine-tuning, but the complexity of building galaxies in all environments remains a challenge. We argue that even basic galaxy properties, such as stellar mass to halo mass, should be treated with errors bars of ˜0.2-0.4 dex.

49 CFR 236.577 - Test, acknowledgement, and cut-in circuits.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 4 2010-10-01 2010-10-01 false Test, acknowledgement, and cut-in circuits. 236.577 Section 236.577 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL..., acknowledgement, and cut-in circuits. Test, acknowledgement, and cut-in circuits shall be tested at least once...

First measurement of H I 21 cm emission from a GRB host galaxy indicates a post-merger system

NASA Astrophysics Data System (ADS)

Arabsalmani, Maryam; Roychowdhury, Sambit; Zwaan, Martin A.; Kanekar, Nissim; Michałowski, Michał J.

2015-11-01

We report the detection and mapping of atomic hydrogen in H I 21 cm emission from ESO 184-G82, the host galaxy of the gamma-ray burst 980425. This is the first instance where H I in emission has been detected from a galaxy hosting a gamma-ray burst (GRB). ESO 184-G82 is an isolated galaxy and contains a Wolf-Rayet region close to the location of the GRB and the associated supernova, SN 1998bw. This is one of the most luminous H II regions identified in the local Universe, with a very high inferred density of star formation. The H I 21 cm observations reveal a high H I mass for the galaxy, twice as large as the stellar mass. The spatial and velocity distribution of the H I 21 cm emission reveals a disturbed rotating gas disc, which suggests that the galaxy has undergone a recent minor merger that disrupted its rotation. We find that the Wolf-Rayet region and the GRB are both located in the highest H I column density region of the galaxy. We speculate that the merger event has resulted in shock compression of the gas, triggering extreme star formation activity, and resulting in the formation of both the Wolf-Rayet region and the GRB. The high H I column density environment of the GRB is consistent with the high H I column densities seen in absorption in the host galaxies of high-redshift GRBs.

Kinematical Modeling of WARPS in the H i Disks of Galaxies

NASA Astrophysics Data System (ADS)

Christodoulou, Dimitris M.; Tohline, Joel E.; Steiman-Cameron, Thomas Y.

1993-10-01

°. The overall position of the warp and the gross geometric shape of the halo have been determined unambiguously only in cases where the twisting of the warp is relatively strong. (Examples of galaxies whose disks sit in an oblate halo are M33, M83, NGC 2805, NGC 2841, and NGC 3718; prolate halos appear to surround NGC 5033 and NGC 5055; and ambiguous cases, at present permitting equally good oblate and prolate halo models, are M31, NGC 300, NGC 3079, NGC 3198, NGC 6946, NGC 7331, and IC 342). There appears to be a high degree of correlation between the twisting angles of kinematical models and precession angles derived from dynamical arguments. This correlation gives us considerable confidence that the kinematically identified twists in warped H I layers are real and that the general dynamical picture that has been put forward to explain their existence is correct. Adopting a scale-free, logarithmic halo potential having a quadrupole distortion η, we conclude specifically that in each of these twisted warped disk systems the product ητ8 is approximately equal to 1, where τ8 is the age of the warped layer in 108 yr.

Galaxy bias from galaxy-galaxy lensing in the DES Science Verification Data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prat, J.; et al.

We present a measurement of galaxy-galaxy lensing around a magnitude-limited (more » $$i_{AB} < 22.5$$) sample of galaxies selected from the Dark Energy Survey Science Verification (DES-SV) data. We split these lenses into three photometric-redshift bins from 0.2 to 0.8, and determine the product of the galaxy bias $b$ and cross-correlation coefficient between the galaxy and dark matter overdensity fields $r$ in each bin, using scales above 4 Mpc/$h$ comoving, where we find the linear bias model to be valid given our current uncertainties. We compare our galaxy bias results from galaxy-galaxy lensing with those obtained from galaxy clustering (Crocce et al. 2016) and CMB lensing (Giannantonio et al. 2016) for the same sample of galaxies, and find our measurements to be in good agreement with those in Crocce et al. (2016), while, in the lowest redshift bin ($$z\\sim0.3$$), they show some tension with the findings in Giannantonio et al. (2016). Our results are found to be rather insensitive to a large range of systematic effects. We measure $$b\\cdot r$$ to be $$0.87\\pm 0.11$$, $$1.12 \\pm 0.16$$ and $$1.24\\pm 0.23$$, respectively for the three redshift bins of width $$\\Delta z = 0.2$$ in the range $0.2« less

The EAGLE simulations: atomic hydrogen associated with galaxies

NASA Astrophysics Data System (ADS)

Crain, Robert A.; Bahé, Yannick M.; Lagos, Claudia del P.; Rahmati, Alireza; Schaye, Joop; McCarthy, Ian G.; Marasco, Antonino; Bower, Richard G.; Schaller, Matthieu; Theuns, Tom; van der Hulst, Thijs

2017-02-01

We examine the properties of atomic hydrogen (H I) associated with galaxies in the Evolution and Assembly of GaLaxies and their Environments (EAGLE) simulations of galaxy formation. EAGLE's feedback parameters were calibrated to reproduce the stellar mass function and galaxy sizes at z = 0.1, and we assess whether this calibration also yields realistic H I properties. We estimate the self-shielding density with a fitting function calibrated using radiation transport simulations, and correct for molecular hydrogen with empirical or theoretical relations. The `standard-resolution' simulations systematically underestimate H I column densities, leading to an H I deficiency in low-mass (M⋆ < 1010 M⊙) galaxies and poor reproduction of the observed H I mass function. These shortcomings are largely absent from EAGLE simulations featuring a factor of 8 (2) better mass (spatial) resolution, within which the H I mass of galaxies evolves more mildly from z = 1 to 0 than in the standard-resolution simulations. The largest volume simulation reproduces the observed clustering of H I systems, and its dependence on H I richness. At fixed M⋆, galaxies acquire more H I in simulations with stronger feedback, as they become associated with more massive haloes and higher infall rates. They acquire less H I in simulations with a greater star formation efficiency, since the star formation and feedback necessary to balance the infall rate is produced by smaller gas reservoirs. The simulations indicate that the H I of present-day galaxies was acquired primarily by the smooth accretion of ionized, intergalactic gas at z ≃ 1, which later self-shields, and that only a small fraction is contributed by the reincorporation of gas previously heated strongly by feedback. H I reservoirs are highly dynamic: over 40 per cent of H I associated with z = 0.1 galaxies is converted to stars or ejected by z = 0.

Galaxy-galaxy weak gravitational lensing in f(R) gravity

NASA Astrophysics Data System (ADS)

Li, Baojiu; Shirasaki, Masato

2018-03-01

We present an analysis of galaxy-galaxy weak gravitational lensing (GGL) in chameleon f(R) gravity - a leading candidate of non-standard gravity models. For the analysis, we have created mock galaxy catalogues based on dark matter haloes from two sets of numerical simulations, using a halo occupation distribution (HOD) prescription which allows a redshift dependence of galaxy number density. To make a fairer comparison between the f(R) and Λ cold dark matter (ΛCDM) models, their HOD parameters are tuned so that the galaxy two-point correlation functions in real space (and therefore the projected two-point correlation functions) match. While the f(R) model predicts an enhancement of the convergence power spectrum by up to ˜ 30 per cent compared to the standard ΛCDM model with the same parameters, the maximum enhancement of GGL is only half as large and less than 5 per cent on separations above ˜1-2 h-1 Mpc, because the latter is a cross-correlation of shear (or matter, which is more strongly affected by modified gravity) and galaxy (which is weakly affected given the good match between galaxy autocorrelations in the two models) fields. We also study the possibility of reconstructing the matter power spectrum by combination of GGL and galaxy clustering in f(R) gravity. We find that the galaxy-matter cross-correlation coefficient remains at unity down to ˜2-3 h-1 Mpc at relevant redshifts even in f(R) gravity, indicating joint analysis of GGL and galaxy clustering can be a powerful probe of matter density fluctuations in chameleon gravity. The scale dependence of the model differences in their predictions of GGL can potentially allows us to break the degeneracy between f(R) gravity and other cosmological parameters such as Ωm and σ8.

Comparing Hα and H I Surveys as Means to a Complete Local Galaxy Catalog in the Advanced LIGO/Virgo Era

NASA Astrophysics Data System (ADS)

Metzger, Brian D.; Kaplan, David L.; Berger, Edo

2013-02-01

Identifying the electromagnetic counterparts of gravitational wave (GW) sources detected by upcoming networks of advanced ground-based interferometers will be challenging, due in part to the large number of unrelated astrophysical transients within the ~10-100 deg2 sky localizations. A potential way to greatly reduce the number of such false positives is to limit detailed follow-up to only those candidates near galaxies within the GW sensitivity range of ~200 Mpc for binary neutron star mergers. Such a strategy is currently hindered by the fact that galaxy catalogs are grossly incomplete within this volume. Here, we compare two methods for completing the local galaxy catalog: (1) a narrowband Hα imaging survey and (2) an H I emission line radio survey. Using Hα fluxes, stellar masses (M sstarf), and star formation rates (SFRs) from galaxies in the Sloan Digital Sky Survey (SDSS), combined with H I data from the GALEX Arecibo SDSS Survey and the Herschel Reference Survey, we estimate that an Hα survey with a luminosity sensitivity of L Hα = 1040 erg s-1 at 200 Mpc could achieve a completeness of f Hα SFR ≈ 75% with respect to total SFR, but only f_{M_{\\star }}^{Hα}≈ 33% with respect to M sstarf (due to lack of sensitivity to early-type galaxies). These numbers are significantly lower than those achieved by an idealized spectroscopic survey due to the loss of Hα flux resulting from resolving out nearby galaxies and the inability to correct for the underlying stellar continuum. An H I survey with sensitivity similar to the proposed WALLABY survey on ASKAP could achieve f_SFR^{H I}≈ 80% and f_{M_{\\star}}^{H I}≈ 50%, somewhat higher than that of the Hα survey. Finally, both Hα and H I surveys should achieve >~ 50% completeness with respect to the host galaxies of short-duration gamma-ray bursts, which may trace the population of binary neutron star mergers.

On the (Non)Evolution of H I Gas in Galaxies Over Cosmic Time

NASA Astrophysics Data System (ADS)

Prochaska, J. Xavier; Wolfe, Arthur M.

2009-05-01

We present new results on the frequency distribution of projected H I column densities f(N H I , X), total comoving covering fraction, and integrated mass densities ρH I of high-redshift, H I galactic gas from a survey of damped Lyα systems (DLAs) in the Sloan Digital Sky Survey, Data Release 5. For the full sample spanning z = 2.2-5 (738 DLAs), f(N H I , X) is well fitted by a double power law with a break column density Nd = 1021.55±0.04 cm-2 and low/high-end exponents α = -2.00 ± 0.05, - 6.4+1.1 -1.6. The shape of f(N H I , X) is invariant during this redshift interval and also follows the projected surface density distribution of present-day H I disks as inferred from 21 cm observations. We conclude that H I gas has been distributed in a self-similar fashion for the past 12 Gyr. The normalization of f(N H I , X), in contrast, decreases by a factor of 2 during the ≈2 Gyr interval from z = 4-2.2 with coincident decreases in both the total covering fraction and ρH I . At z ≈ 2, these quantities match the present-day values suggesting no evolution during the past ≈10 Gyr. We argue that the evolution at early times is driven by "violent" processes that removes gas from nearly half the galaxies at z ≈ 3 establishing the antecedents of current early-type galaxies. The perceived constancy of ρH I , meanwhile, implies that H I gas is a necessary but insufficient precondition for star formation and that the global star formation rate is driven by the accretion and condensation of fresh gas from the intergalactic medium.

BUDHIES II: a phase-space view of H I gas stripping and star formation quenching in cluster galaxies

NASA Astrophysics Data System (ADS)

Jaffé, Yara L.; Smith, Rory; Candlish, Graeme N.; Poggianti, Bianca M.; Sheen, Yun-Kyeong; Verheijen, Marc A. W.

2015-04-01

We investigate the effect of ram-pressure from the intracluster medium on the stripping of H I gas in galaxies in a massive, relaxed, X-ray bright, galaxy cluster at z = 0.2 from the Blind Ultra Deep H I Environmental Survey (BUDHIES). We use cosmological simulations, and velocity versus position phase-space diagrams to infer the orbital histories of the cluster galaxies. In particular, we embed a simple analytical description of ram-pressure stripping in the simulations to identify the regions in phase-space where galaxies are more likely to have been sufficiently stripped of their H I gas to fall below the detection limit of our survey. We find a striking agreement between the model predictions and the observed location of H I-detected and non-detected blue (late-type) galaxies in phase-space, strongly implying that ram-pressure plays a key role in the gas removal from galaxies, and that this can happen during their first infall into the cluster. However, we also find a significant number of gas-poor, red (early-type) galaxies in the infall region of the cluster that cannot easily be explained with our model of ram-pressure stripping alone. We discuss different possible additional mechanisms that could be at play, including the pre-processing of galaxies in their previous environment. Our results are strengthened by the distribution of galaxy colours (optical and UV) in phase-space, that suggests that after a (gas-rich) field galaxy falls into the cluster, it will lose its gas via ram-pressure stripping, and as it settles into the cluster, its star formation will decay until it is completely quenched. Finally, this work demonstrates the utility of phase-space diagrams to analyse the physical processes driving the evolution of cluster galaxies, in particular H I gas stripping.

A study of the H I and optical properties of Low Surface Brightness galaxies: spirals, dwarfs, and irregulars

NASA Astrophysics Data System (ADS)

Honey, M.; van Driel, W.; Das, M.; Martin, J.-M.

2018-06-01

We present a study of the H I and optical properties of nearby (z ≤ 0.1) Low Surface Brightness galaxies (LSBGs). We started with a literature sample of ˜900 LSBGs and divided them into three morphological classes: spirals, irregulars, and dwarfs. Of these, we could use ˜490 LSBGs to study their H I and stellar masses, colours, and colour-magnitude diagrams, and local environment, compare them with normal, High Surface Brightness (HSB) galaxies and determine the differences between the three morphological classes. We found that LSB and HSB galaxies span a similar range in H I and stellar masses, and have a similar M_{H I}/M⋆-M⋆ relationship. Among the LSBGs, as expected, the spirals have the highest average H I and stellar masses, both of about 109.8 M⊙. The LSGBs' (g - r) integrated colour is nearly constant as function of H I mass for all classes. In the colour-magnitude diagram, the spirals are spread over the red and blue regions whereas the irregulars and dwarfs are confined to the blue region. The spirals also exhibit a steeper slope in the M_{H I}/M⋆-M⋆ plane. Within their local environment, we confirmed that LSBGs are more isolated than HSB galaxies, and LSB spirals more isolated than irregulars and dwarfs. Kolmogorov-Smirnov statistical tests on the H I mass, stellar mass, and number of neighbours indicate that the spirals are a statistically different population from the dwarfs and irregulars. This suggests that the spirals may have different formation and H I evolution than the dwarfs and irregulars.

Cosmic clocks: a tight radius-velocity relationship for H I-selected galaxies

NASA Astrophysics Data System (ADS)

Meurer, Gerhardt R.; Obreschkow, Danail; Wong, O. Ivy; Zheng, Zheng; Audcent-Ross, Fiona M.; Hanish, D. J.

2018-05-01

H I-selected galaxies obey a linear relationship between their maximum detected radius Rmax and rotational velocity. This result covers measurements in the optical, ultraviolet, and H I emission in galaxies spanning a factor of 30 in size and velocity, from small dwarf irregulars to the largest spirals. Hence, galaxies behave as clocks, rotating once a Gyr at the very outskirts of their discs. Observations of a large optically selected sample are consistent, implying this relationship is generic to disc galaxies in the low redshift Universe. A linear radius-velocity relationship is expected from simple models of galaxy formation and evolution. The total mass within Rmax has collapsed by a factor of 37 compared to the present mean density of the Universe. Adopting standard assumptions, we find a mean halo spin parameter λ in the range 0.020-0.035. The dispersion in λ, 0.16 dex, is smaller than expected from simulations. This may be due to the biases in our selection of disc galaxies rather than all haloes. The estimated mass densities of stars and atomic gas at Rmax are similar (˜0.5 M⊙ pc-2), indicating outer discs are highly evolved. The gas consumption and stellar population build time-scales are hundreds of Gyr, hence star formation is not driving the current evolution of outer discs. The estimated ratio between Rmax and disc scalelength is consistent with long-standing predictions from monolithic collapse models. Hence, it remains unclear whether disc extent results from continual accretion, a rapid initial collapse, secular evolution, or a combination thereof.

PRIMUS: Galaxy clustering as a function of luminosity and color at 0.2 < z < 1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Skibba, Ramin A.; Smith, M. Stephen M.; Coil, Alison L.

2014-04-01

We present measurements of the luminosity and color-dependence of galaxy clustering at 0.2 < z < 1.0 in the Prism Multi-object Survey. We quantify the clustering with the redshift-space and projected two-point correlation functions, ξ(r{sub p} , π) and w{sub p} (r{sub p} ), using volume-limited samples constructed from a parent sample of over ∼130, 000 galaxies with robust redshifts in seven independent fields covering 9 deg{sup 2} of sky. We quantify how the scale-dependent clustering amplitude increases with increasing luminosity and redder color, with relatively small errors over large volumes. We find that red galaxies have stronger small-scale (0.1more » Mpc h {sup –1} < r{sub p} < 1 Mpc h {sup –1}) clustering and steeper correlation functions compared to blue galaxies, as well as a strong color dependent clustering within the red sequence alone. We interpret our measured clustering trends in terms of galaxy bias and obtain values of b {sub gal} ≈ 0.9-2.5, quantifying how galaxies are biased tracers of dark matter depending on their luminosity and color. We also interpret the color dependence with mock catalogs, and find that the clustering of blue galaxies is nearly constant with color, while redder galaxies have stronger clustering in the one-halo term due to a higher satellite galaxy fraction. In addition, we measure the evolution of the clustering strength and bias, and we do not detect statistically significant departures from passive evolution. We argue that the luminosity- and color-environment (or halo mass) relations of galaxies have not significantly evolved since z ∼ 1. Finally, using jackknife subsampling methods, we find that sampling fluctuations are important and that the COSMOS field is generally an outlier, due to having more overdense structures than other fields; we find that 'cosmic variance' can be a significant source of uncertainty for high-redshift clustering measurements.« less

The Arecibo Galaxy Environment Survey - VII. A dense filament with extremely long H I streams

NASA Astrophysics Data System (ADS)

Taylor, R.; Minchin, R. F.; Herbst, H.; Davies, J. I.; Rodriguez, R.; Vazquez, C.

2014-09-01

We present completed observations of the NGC 7448 galaxy group and background volume as part of the blind neutral hydrogen Arecibo Galaxy Environment Survey. Our observations cover a region spanning 5°× 4°, over a redshift range of approximately -2000 1. A total of 334 objects are detected, mostly in three overdensities at cz ˜ 7500, cz ˜ 9600 and cz ˜ 11 400 km s-1. The galaxy density is extremely high (15 deg-2) and many (˜24 per cent) show signs of extended H I emission, including some features as much as 800 kpc in projected length. We describe the overall characteristics of this environment: kinematics, typical galaxy colours and mass-to-light ratios, and substructure. To aid in the cataloguing of this data set, we present a new FITS viewer (FRELLED: FITS Realtime Explorer of Low Latency in Every Dimension). This incorporates interactive source cataloguing tools which increase our source extraction speed by approximately a factor of 50.

Abell 1367: a high fraction of late-type galaxies displaying H I morphological and kinematic perturbations

NASA Astrophysics Data System (ADS)

Scott, T. C.; Brinks, E.; Cortese, L.; Boselli, A.; Bravo-Alfaro, H.

2018-04-01

To investigate the effects the cluster environment has on late-type galaxies (LTGs), we studied H I perturbation signatures for all Abell 1367 LTGs with H I detections. We used new Very Large Array H I observations combined with AGES single-dish blind survey data. Our study indicates that the asymmetry between the high- and low-velocity wings of the characteristic double-horn-integrated H I spectrum as measured by the asymmetry parameter, A_{flux}, can be a useful diagnostic for ongoing and/or recent H I stripping. 26 per cent of A1367 LTGs have an A_{flux} ratio, more asymmetrical than 3 times the 1σ spread in the A_{flux} ratio distribution of an undisturbed sample of isolated galaxies (2 per cent) and samples from other denser environments (10 per cent-20 per cent). Over half of the A1367 LTGs, which are members of groups or pairs, have an A_{flux} ratio larger than twice the 1σ spread found in the isolated sample. This suggests intergroup/pair interactions could be making a significant contribution to the LTGs displaying such A_{flux} ratios. The study also demonstrates that the definition of the H I offset from the optical centre of LTGs is resolution dependent, suggesting that unresolved AGES H I offsets that are significantly larger than the pointing uncertainties (>2σ), reflect interactions which have asymmetrically displaced, significant masses of lower density H I, while having minimal impact on the location of the highest density H I in resolved maps. The distribution of A_{flux} from a comparable sample of Virgo galaxies provides a clear indication that the frequency of H I profile perturbations is lower than in A1367.

JET-SHOCKED H{sub 2} AND CO IN THE ANOMALOUS ARMS OF MOLECULAR HYDROGEN EMISSION GALAXY NGC 4258

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ogle, P. M.; Lanz, L.; Appleton, P. N., E-mail: ogle@ipac.caltech.edu

2014-06-20

We present a Spitzer Infrared Spectrograph map of H{sub 2} emission from the nearby galaxy NGC 4258 (Messier 106). The H{sub 2} emission comes from 9.4 ± 0.4 × 10{sup 6} M {sub ☉} of warm molecular hydrogen heated to 240-1040 K in the inner anomalous arms, a signature of jet interaction with the galaxy disk. The spectrum is that of a molecular hydrogen emission galaxy (MOHEG), with a large ratio of H{sub 2} over 7.7 μm polycyclic aromatic hydrocarbon emission (0.37), characteristic of shocked molecular gas. We find close spatial correspondence between the H{sub 2} and CO emission from the anomalousmore » arms. Our estimate of cold molecular gas mass based on CO emission is 10 times greater than our estimate of 1.0 × 10{sup 8} M {sub ☉} based on dust emission. We suggest that the X {sub CO} value is 10 times lower than the Milky Way value because of high kinetic temperature and enhanced turbulence. The H{sub 2} disk has been overrun and is being shocked by the jet cocoon, and much of the gas originally in the disk has been ejected into the galaxy halo in an X-ray hot outflow. We measure a modest star formation rate of 0.08 M {sub ☉} yr{sup –1} in the central 3.4 kpc{sup 2} that is consistent with the remaining gas surface density.« less

A two-point diagnostic for the H II galaxy Hubble diagram

NASA Astrophysics Data System (ADS)

Leaf, Kyle; Melia, Fulvio

2018-03-01

A previous analysis of starburst-dominated H II galaxies and H II regions has demonstrated a statistically significant preference for the Friedmann-Robertson-Walker cosmology with zero active mass, known as the Rh = ct universe, over Λcold dark matter (ΛCDM) and its related dark-matter parametrizations. In this paper, we employ a two-point diagnostic with these data to present a complementary statistical comparison of Rh = ct with Planck ΛCDM. Our two-point diagnostic compares, in a pairwise fashion, the difference between the distance modulus measured at two redshifts with that predicted by each cosmology. Our results support the conclusion drawn by a previous comparative analysis demonstrating that Rh = ct is statistically preferred over Planck ΛCDM. But we also find that the reported errors in the H II measurements may not be purely Gaussian, perhaps due to a partial contamination by non-Gaussian systematic effects. The use of H II galaxies and H II regions as standard candles may be improved even further with a better handling of the systematics in these sources.

The Radial Distribution of Star Formation in Galaxies at Z approximately 1 from the 3D-HST Survey

NASA Technical Reports Server (NTRS)

Nelson, Erica June; vanDokkum, Pieter G.; Momcheva, Ivelina; Brammer, Gabriel; Lundgren, Britt; Skelton, Rosalind E.; Whitaker, Katherine E.; DaCunha, Elisabete; Schreiber, Natascha Foerster; Franx, Marijn;

Galaxy bias from galaxy-galaxy lensing in the DES science verification data

NASA Astrophysics Data System (ADS)

Prat, J.; Sánchez, C.; Miquel, R.; Kwan, J.; Blazek, J.; Bonnett, C.; Amara, A.; Bridle, S. L.; Clampitt, J.; Crocce, M.; Fosalba, P.; Gaztanaga, E.; Giannantonio, T.; Hartley, W. G.; Jarvis, M.; MacCrann, N.; Percival, W. J.; Ross, A. J.; Sheldon, E.; Zuntz, J.; Abbott, T. M. C.; Abdalla, F. B.; Annis, J.; Benoit-Lévy, A.; Bertin, E.; Brooks, D.; Burke, D. L.; Carnero Rosell, A.; Carrasco Kind, M.; Carretero, J.; Castander, F. J.; da Costa, L. N.; DePoy, D. L.; Desai, S.; Diehl, H. T.; Doel, P.; Eifler, T. F.; Evrard, A. E.; Fausti Neto, A.; Flaugher, B.; Frieman, J.; Gerdes, D. W.; Goldstein, D. A.; Gruen, D.; Gruendl, R. A.; Gutierrez, G.; Honscheid, K.; James, D. J.; Kuehn, K.; Kuropatkin, N.; Lahav, O.; Lima, M.; Marshall, J. L.; Melchior, P.; Menanteau, F.; Nord, B.; Plazas, A. A.; Reil, K.; Romer, A. K.; Roodman, A.; Sanchez, E.; Scarpine, V.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Thomas, D.; Walker, A. R.

2018-01-01

We present a measurement of galaxy-galaxy lensing around a magnitude-limited (iAB < 22.5) sample of galaxies from the dark energy survey science verification (DES-SV) data. We split these lenses into three photometric-redshift bins from 0.2 to 0.8, and determine the product of the galaxy bias b and cross-correlation coefficient between the galaxy and dark matter overdensity fields r in each bin, using scales above 4 h-1 Mpc comoving, where we find the linear bias model to be valid given our current uncertainties. We compare our galaxy bias results from galaxy-galaxy lensing with those obtained from galaxy clustering and CMB lensing for the same sample of galaxies, and find our measurements to be in good agreement with those in Crocce et al., while, in the lowest redshift bin (z ∼ 0.3), they show some tension with the findings in Giannantonio et al. We measure b · r to be 0.87 ± 0.11, 1.12 ± 0.16 and 1.24 ± 0.23, respectively, for the three redshift bins of width Δz = 0.2 in the range 0.2 < z < 0.8, defined with the photometric-redshift algorithm BPZ. Using a different code to split the lens sample, TPZ, leads to changes in the measured biases at the 10-20 per cent level, but it does not alter the main conclusion of this work: when comparing with Crocce et al. we do not find strong evidence for a cross-correlation parameter significantly below one in this galaxy sample, except possibly at the lowest redshift bin (z ∼ 0.3), where we find r = 0.71 ± 0.11 when using TPZ, and 0.83 ± 0.12 with BPZ.

25 CFR 577.8 - Request to limit disclosure of confidential information.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 25 Indians 2 2010-04-01 2010-04-01 false Request to limit disclosure of confidential information. 577.8 Section 577.8 Indians NATIONAL INDIAN GAMING COMMISSION, DEPARTMENT OF THE INTERIOR COMPLIANCE..., or to disclose the information voluntarily to all parties. (e) If the presiding official determines...

DETERMINING THE NATURE OF THE EXTENDED H I STRUCTURE AROUND LITTLE THINGS DWARF GALAXY NGC 1569

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Megan, E-mail: mjohnson@nrao.edu; National Radio Astronomy Observatory, P.O. Box 2, Green Bank, WV 24915

2013-06-15

This work presents an extended, neutral hydrogen emission map around Magellanic-type dwarf irregular galaxy (dIm) NGC 1569. In the spring of 2010, the Robert C. Byrd Green Bank Telescope was used to map a 9 Degree-Sign Multiplication-Sign 2 Degree-Sign region in H I line emission that includes NGC 1569 and IC 342 as well as two other dwarf galaxies. The primary objective for these observations was to search for structures potentially connecting NGC 1569 with IC 342 group members in order to trace previous interactions and thus, provide an explanation for the starburst and peculiar kinematics prevalent in NGC 1569.more » A large, half-degree diameter H I cloud was detected that shares the same position and velocity as NGC 1569. Also, two long structures were discovered that are reminiscent of intergalactic filaments extending out in a V-shaped manner from NGC 1569 toward UGCA 92, a nearby dwarf galaxy. These filamentary structures extend for about 1. Degree-Sign 5, which is 77 kpc at NGC 1569. There is a continuous velocity succession with the 0. Degree-Sign 5 H I cloud, filaments, and main body of the galaxy. The 0. Degree-Sign 5 H I cloud and filamentary structures may be foreground Milky Way, but are suggestive as possible remnants of an interaction between NGC 1569 and UGCA 92. The data also show two tidal tails extending from UGCA 86 and IC 342, respectively. These structures may be part of a continuous H I bridge but more data are needed to determine if this is the case.« less

From H I to Stars: H I Depletion in Starbursts and Star-forming Galaxies in the ALFALFA Hα Survey

NASA Astrophysics Data System (ADS)

Jaskot, A. E.; Oey, M. S.; Salzer, J. J.; Van Sistine, A.; Bell, E. F.; Haynes, M. P.

2015-07-01

H i in galaxies traces the fuel for future star formation and reveals the effects of feedback on neutral gas. Using a statistically uniform, H i-selected sample of 565 galaxies from the Arecibo Legacy Fast ALFA (ALFALFA) Hα survey, we explore H i properties as a function of star formation activity. ALFALFA Hα provides R-band and Hα imaging for a volume-limited subset of the 21 cm ALFALFA survey. We identify eight starbursts based on Hα equivalent width and six with enhanced star formation relative to the main sequence. Both starbursts and non-starbursts have similar H i-to-stellar mass ratios ({M}{{H} {{I}}}/{M}*), which suggests that feedback is not depleting the starbursts’ H i. Consequently, the starbursts do have shorter H i depletion times ({t}{dep}), implying more efficient H i-to-H2 conversion. While major mergers likely drive this enhanced efficiency in some starbursts, the lowest-mass starbursts may experience periodic bursts, consistent with enhanced scatter in {t}{dep} at low {M}*. Two starbursts appear to be pre-coalescence mergers; their elevated {M}{{H} {{I}}}/{M}* suggest that H i-to-H2 conversion is still ongoing at this stage. By comparing with the GASS sample, we find that {t}{dep} anticorrelates with stellar surface density for disks, while spheroids show no such trend. Among early-type galaxies, {t}{dep} does not correlate with bulge-to-disk ratio; instead, the gas distribution may determine the star formation efficiency. Finally, the weak connection between galaxies’ specific star formation rates and {M}{{H} {{I}}}/{M}* contrasts with the well-known correlation between {M}{{H} {{I}}}/{M}* and color. We show that dust extinction can explain the H i-color trend, which may arise from the relationship between {M}*, {M}{{H} {{I}}}, and metallicity.

The ALHAMBRA survey: evolution of galaxy clustering since z ˜ 1

NASA Astrophysics Data System (ADS)

Arnalte-Mur, P.; Martínez, V. J.; Norberg, P.; Fernández-Soto, A.; Ascaso, B.; Merson, A. I.; Aguerri, J. A. L.; Castander, F. J.; Hurtado-Gil, L.; López-Sanjuan, C.; Molino, A.; Montero-Dorta, A. D.; Stefanon, M.; Alfaro, E.; Aparicio-Villegas, T.; Benítez, N.; Broadhurst, T.; Cabrera-Caño, J.; Cepa, J.; Cerviño, M.; Cristóbal-Hornillos, D.; del Olmo, A.; González Delgado, R. M.; Husillos, C.; Infante, L.; Márquez, I.; Masegosa, J.; Moles, M.; Perea, J.; Pović, M.; Prada, F.; Quintana, J. M.

2014-06-01

We study the clustering of galaxies as function of luminosity and redshift in the range 0.35 < z < 1.25 using data from the Advanced Large Homogeneous Area Medium-Band Redshift Astronomical (ALHAMBRA) survey. The ALHAMBRA data used in this work cover 2.38 deg2 in seven independent fields, after applying a detailed angular selection mask, with accurate photometric redshifts, σz ≲ 0.014(1 + z), down to IAB < 24. Given the depth of the survey, we select samples in B-band luminosity down to Lth ≃ 0.16L* at z = 0.9. We measure the real-space clustering using the projected correlation function, accounting for photometric redshifts uncertainties. We infer the galaxy bias, and study its evolution with luminosity. We study the effect of sample variance, and confirm earlier results that the Cosmic Evolution Survey (COSMOS) and European Large Area ISO Survey North 1 (ELAIS-N1) fields are dominated by the presence of large structures. For the intermediate and bright samples, Lmed ≳ 0.6L*, we obtain a strong dependence of bias on luminosity, in agreement with previous results at similar redshift. We are able to extend this study to fainter luminosities, where we obtain an almost flat relation, similar to that observed at low redshift. Regarding the evolution of bias with redshift, our results suggest that the different galaxy populations studied reside in haloes covering a range in mass between log10[Mh/( h-1 M⊙)] ≳ 11.5 for samples with Lmed ≃ 0.3L* and log10[Mh/( h-1 M⊙)] ≳ 13.0 for samples with Lmed ≃ 2L*, with typical occupation numbers in the range of ˜1-3 galaxies per halo.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wagg, Jeff; Pope, Alexandra; Alberts, Stacey

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 factormore » 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.« less

Weak-Lensing Determination of the Mass in Galaxy Halos

NASA Astrophysics Data System (ADS)

Smith, D. R.; Bernstein, G. M.; Fischer, P.; Jarvis, M.

2001-04-01

We detect the weak gravitational lensing distortion of 450,000 background galaxies (20galaxies (R<18) selected from the Las Campanas Redshift Survey (LCRS). This is the first detection of weak lensing by field galaxies of known redshift, and as such permits us to reconstruct the shear profile of the typical field galaxy halo in absolute physical units (modulo H0), and to investigate the dependence of halo mass upon galaxy luminosity. This is also the first galaxy-galaxy lensing study for which the calibration errors due to uncertainty in the background galaxy redshift distribution and the seeing correction are negligible. Within a projected radius of 200 h-1 kpc, the shear profile is consistent with an isothermal profile with circular velocity vc=164+/-20 km s-1 for an L* galaxy, consistent with the typical circular velocity for the disks of spirals at this luminosity. This halo mass normalization, combined with the halo profile derived by Fischer and coworkers from a galaxy-galaxy lensing analysis of the Sloan Digital Sky Survey, places a lower limit of (2.7+/-0.6)×1012 h-1 Msolar on the mass of an L* galaxy halo, in good agreement with the satellite galaxy studies of Zaritsky et al. Given the known luminosity function of LCRS galaxies, and assuming that M~Lβ for galaxies, we determine that the mass within 260 h-1 kpc of normal galaxies contributes Ω=0.16+/-0.03 to the density of the universe (for β=1) or Ω=0.24+/-0.06 for β=0.5. These lensing data suggest that 0.6<β<2.4 (95% confidence level), only marginally in agreement with the usual β~0.5 Faber-Jackson or Tully-Fisher scaling. This is the most complete direct inventory of the matter content of the universe to date.

GALAXY GROWTH BY MERGING IN THE NEARBY UNIVERSE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang Tao; Hogg, David W.; Blanton, Michael R., E-mail: david.hogg@nyu.edu

2012-11-10

We measure the mass growth rate by merging for a wide range of galaxy types. We present the small-scale (0.014 h {sup -1} {sub 70} Mpc < r < 11 h {sub 70} {sup -1} Mpc) projected cross-correlation functions w(r {sub p}) of galaxy subsamples from the spectroscopic sample of the NYU Value-Added Galaxy Catalog (5 Multiplication-Sign 10{sup 5} galaxies of redshifts 0.03 < z < 0.15) with galaxy subsamples from the Sloan Digital Sky Survey imaging (4 Multiplication-Sign 10{sup 7} galaxies). We use smooth fits to de-project the two-dimensional functions w(r {sub p}) to obtain smooth three-dimensional real-space cross-correlationmore » functions {xi}(r) for each of several spectroscopic subsamples with each of several imaging subsamples. Because close pairs are expected to merge, the three-space functions and dynamical evolution time estimates provide galaxy accretion rates. We find that the accretion onto massive blue galaxies and onto red galaxies is dominated by red companions, and that onto small-mass blue galaxies, red and blue galaxies make comparable contributions. We integrate over all types of companions and find that at fixed stellar mass, the total fractional accretion rates onto red galaxies ({approx}3 h {sub 70} percent per Gyr) are greater than that onto blue galaxies ({approx}1 h {sub 70} percent per Gyr). These rates are almost certainly overestimates because we have assumed that all close pairs merge as quickly as the merger time that we used. One conclusion of this work is that if the total growth of red galaxies from z = 1 to z = 0 is mainly due to merging, the merger rates must have been higher in the past.« less

Systematic Variations in CO2/H2O Ice Abundance Ratios in Nearby Galaxies Found with AKARI Near-infrared Spectroscopy

NASA Astrophysics Data System (ADS)

Yamagishi, M.; Kaneda, H.; Ishihara, D.; Oyabu, S.; Onaka, T.; Shimonishi, T.; Suzuki, T.

2015-07-01

We report CO2/H2O ice abundance ratios in seven nearby star-forming galaxies based on the AKARI near-infrared (2.5-5.0 μm) spectra. The CO2/H2O ice abundance ratios show clear variations between 0.05 and 0.2 with the averaged value of 0.14 ± 0.01. The previous study on M82 revealed that the CO2/H2O ice abundance ratios strongly correlate with the intensity ratios of the hydrogen recombination Brα line to the polycyclic aromatic hydrocarbon (PAH) 3.3 μm feature. In the present study, however, we find no correlation for the seven galaxies as a whole due to systematic differences in the relation between CO2/H2O ice abundance and Brα/PAH 3.3 μm intensity ratios from galaxy to galaxy. This result suggests that there is another parameter that determines the CO2/H2O ice abundance ratios in a galaxy in addition to the Brα/PAH 3.3 μm ratios. We find that the CO2/H2O ice abundance ratios positively correlate with the specific star formation rates of the galaxies. From these results, we conclude that CO2/H2O ice abundance ratios tend to be high in young star-forming galaxies.

The hELENa project - I. Stellar populations of early-type galaxies linked with local environment and galaxy mass

NASA Astrophysics Data System (ADS)

Sybilska, A.; Lisker, T.; Kuntschner, H.; Vazdekis, A.; van de Ven, G.; Peletier, R.; Falcón-Barroso, J.; Vijayaraghavan, R.; Janz, J.

2017-09-01

We present the first in a series of papers in The role of Environment in shaping Low-mass Early-type Nearby galaxies (hELENa) project. In this paper, we combine our sample of 20 low-mass early types (dEs) with 258 massive early types (ETGs) from the ATLAS3D survey - all observed with the SAURON integral field unit - to investigate early-type galaxies' stellar population scaling relations and the dependence of the population properties on local environment, extended to the low-σ regime of dEs. The ages in our sample show more scatter at lower σ values, indicative of less massive galaxies being affected by the environment to a higher degree. The shape of the age-σ relations for cluster versus non-cluster galaxies suggests that cluster environment speeds up the placing of galaxies on the red sequence. While the scaling relations are tighter for cluster than for the field/group objects, we find no evidence for a difference in average population characteristics of the two samples. We investigate the properties of our sample in the Virgo cluster as a function of number density (rather than simple clustrocentric distance) and find that dE ages correlate with the local density such that galaxies in regions of lower density are younger, likely because they are later arrivals to the cluster or have experienced less pre-processing in groups, and consequently used up their gas reservoir more recently. Overall, dE properties correlate more strongly with density than those of massive ETGs, which was expected as less massive galaxies are more susceptible to external influences.

33 CFR 165.T11-577 - Security Zone; Naval Exercise; Pacific Ocean, Coronado, CA.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Security Zone; Naval Exercise; Pacific Ocean, Coronado, CA. 165.T11-577 Section 165.T11-577 Navigation and Navigable Waters COAST GUARD... § 165.T11-577 Security Zone; Naval Exercise; Pacific Ocean, Coronado, CA. (a) Location. The limits of...

Radial gas motions in The H I Nearby Galaxy Survey (THINGS)

NASA Astrophysics Data System (ADS)

Schmidt, Tobias M.; Bigiel, Frank; Klessen, Ralf S.; de Blok, W. J. G.

2016-04-01

The study of 21 cm line observations of atomic hydrogen allows detailed insight into the kinematics of spiral galaxies. We use sensitive high-resolution Very Large Array data from The H I Nearby Galaxy Survey (THINGS) to search for radial gas flows primarily in the outer parts (up to 3 × r25) of 10 nearby spiral galaxies. Inflows are expected to replenish the gas reservoir and fuel star formation under the assumption that galaxies evolve approximately in steady state. We carry out a detailed investigation of existing tilted ring fitting schemes and discover systematics that can hamper their ability to detect signatures of radial flows. We develop a new Fourier decomposition scheme that fits for rotational and radial velocities and simultaneously determines position angle and inclination as a function of radius. Using synthetic velocity fields we show that our novel fitting scheme is less prone to such systematic errors and that it is well suited to detect radial inflows in discs. We apply our fitting scheme to 10 THINGS galaxies and find clear indications of, at least partly previously unidentified, radial gas flows, in particular for NGC 2403 and NGC 3198 and to a lesser degree for NGC 7331, NGC 2903 and NGC 6946. The mass flow rates are of the same order but usually larger than the star formation rates. At least for these galaxies a scenario in which continuous mass accretion feeds star formation seems plausible. The other galaxies show a more complicated picture with either no clear inflow, outward motions or complex kinematic signatures.

LeMMINGs - I. The eMERLIN legacy survey of nearby galaxies. 1.5-GHz parsec-scale radio structures and cores

NASA Astrophysics Data System (ADS)

Baldi, R. D.; Williams, D. R. A.; McHardy, I. M.; Beswick, R. J.; Argo, M. K.; Dullo, B. T.; Knapen, J. H.; Brinks, E.; Muxlow, T. W. B.; Aalto, S.; Alberdi, A.; Bendo, G. J.; Corbel, S.; Evans, R.; Fenech, D. M.; Green, D. A.; Klöckner, H.-R.; Körding, E.; Kharb, P.; Maccarone, T. J.; Martí-Vidal, I.; Mundell, C. G.; Panessa, F.; Peck, A. B.; Pérez-Torres, M. A.; Saikia, D. J.; Saikia, P.; Shankar, F.; Spencer, R. E.; Stevens, I. R.; Uttley, P.; Westcott, J.

2018-05-01

We present the first data release of high-resolution (≤0.2 arcsec) 1.5-GHz radio images of 103 nearby galaxies from the Palomar sample, observed with the eMERLIN array, as part of the LeMMINGs survey. This sample includes galaxies which are active (low-ionization nuclear emission-line regions [LINER] and Seyfert) and quiescent (H II galaxies and absorption line galaxies, ALGs), which are reclassified based upon revised emission-line diagrams. We detect radio emission ≳0.2 mJy for 47/103 galaxies (22/34 for LINERS, 4/4 for Seyferts, 16/51 for H II galaxies, and 5/14 for ALGs) with radio sizes typically of ≲100 pc. We identify the radio core position within the radio structures for 41 sources. Half of the sample shows jetted morphologies. The remaining half shows single radio cores or complex morphologies. LINERs show radio structures more core-brightened than Seyferts. Radio luminosities of the sample range from 1032 to 1040 erg s-1: LINERs and H II galaxies show the highest and lowest radio powers, respectively, while ALGs and Seyferts have intermediate luminosities. We find that radio core luminosities correlate with black hole (BH) mass down to ˜107 M⊙, but a break emerges at lower masses. Using [O III] line luminosity as a proxy for the accretion luminosity, active nuclei and jetted H II galaxies follow an optical Fundamental Plane of BH activity, suggesting a common disc-jet relationship. In conclusion, LINER nuclei are the scaled-down version of FR I radio galaxies; Seyferts show less collimated jets; H II galaxies may host weak active BHs and/or nuclear star-forming cores; and recurrent BH activity may account for ALG properties.

Submillimeter H2O and H2O+emission in lensed ultra- and hyper-luminous infrared galaxies at z 2-4

NASA Astrophysics Data System (ADS)

Yang, C.; Omont, A.; Beelen, A.; González-Alfonso, E.; Neri, R.; Gao, Y.; van der Werf, P.; Weiß, A.; Gavazzi, R.; Falstad, N.; Baker, A. J.; Bussmann, R. S.; Cooray, A.; Cox, P.; Dannerbauer, H.; Dye, S.; Guélin, M.; Ivison, R.; Krips, M.; Lehnert, M.; Michałowski, M. J.; Riechers, D. A.; Spaans, M.; Valiante, E.

2016-11-01

We report rest-frame submillimeter H2O emission line observations of 11 ultra- or hyper-luminous infrared galaxies (ULIRGs or HyLIRGs) at z 2-4 selected among the brightest lensed galaxies discovered in the Herschel-Astrophysical Terahertz Large Area Survey (H-ATLAS). Using the IRAM NOrthern Extended Millimeter Array (NOEMA), we have detected 14 new H2O emission lines. These include five 321-312ortho-H2O lines (Eup/k = 305 K) and nine J = 2 para-H2O lines, either 202-111(Eup/k = 101 K) or 211-202(Eup/k = 137 K). The apparent luminosities of the H2O emission lines are μLH2O 6-21 × 108 L⊙ (3 <μ< 15, where μ is the lens magnification factor), with velocity-integrated line fluxes ranging from 4-15 Jy km s-1. We have also observed CO emission lines using EMIR on the IRAM 30 m telescope in seven sources (most of those have not yet had their CO emission lines observed). The velocity widths for CO and H2O lines are found to be similar, generally within 1σ errors in the same source. With almost comparable integrated flux densities to those of the high-J CO line (ratios range from 0.4 to 1.1), H2O is found to be among the strongest molecular emitters in high-redshift Hy/ULIRGs. We also confirm our previously found correlation between luminosity of H2O (LH2O) and infrared (LIR) that LH2O LIR1.1-1.2, with ournew detections. This correlation could be explained by a dominant role of far-infrared pumping in the H2O excitation. Modelling reveals that the far-infrared radiation fields have warm dust temperature Twarm 45-75 K, H2O column density per unit velocity interval NH2O /ΔV ≳ 0.3 × 1015 cm-2 km-1 s and 100 μm continuum opacity τ100> 1 (optically thick), indicating that H2O is likely to trace highly obscured warm dense gas. However, further observations of J ≥ 4 H2O lines are needed to better constrain the continuum optical depth and other physical conditions of the molecular gas and dust. We have also detected H2O+ emission in three sources. A tight correlation

Deep infrared galaxies

NASA Technical Reports Server (NTRS)

Ashby, Matthew; Houck, J. R.; Hacking, Perry B.

1992-01-01

High signal-to-noise ratio optical spectra of 17 infrared-bright emission-line galaxies near the north ecliptic pole are presented. Reddening-corrected line ratios forbidden O III 5007/H-beta, N II 6583/H-alpha, S II (6716 + 6731)/H-alpha, and O I 6300/H-alpha are used to discriminate between candidate energy generation mechanisms in each galaxy. These criteria have frequently been applied to optically selected samples of galaxies in the past, but this is the first time they have been applied to a set of faint flux-limited infrared-selected objects. The analysis indicates the sample contains seven starburst galaxies and three (AGN). However, seven galaxies in the present sample elude the classification scheme based on these line ratios. It is concluded that a two-component (starburst plus AGN) model for energy generation is inadequate for infrared galaxies.

31 CFR 515.577 - Authorized transactions necessary and ordinarily incident to publishing.

Code of Federal Regulations, 2010 CFR

2010-07-01

... ordinarily incident to publishing. 515.577 Section 515.577 Money and Finance: Treasury Regulations Relating... Authorized transactions necessary and ordinarily incident to publishing. (a) To the extent that such... engage in all transactions necessary and ordinarily incident to the publishing and marketing of...

Extended Source/Galaxy All Sky 1

NASA Image and Video Library

2003-03-27

This panoramic view of the entire sky reveals the distribution of galaxies beyond our Milky Way galaxy, which astronomers call extended sources, as observed by Two Micron All-Sky Survey. The image is constructed from a database of over 1.6 million galaxies listed in the survey's Extended Source Catalog; more than half of the galaxies have never before been catalogued. The image is a representation of the relative brightnesses of these million-plus galaxies, all observed at a wavelength of 2.2 microns. The brightest and nearest galaxies are represented in blue, and the faintest, most distant ones are in red. This color scheme gives insights into the three dimensional large-scale structure of the nearby universe with the brightest, closest clusters and superclusters showing up as the blue and bluish-white features. The dark band in this image shows the area of the sky where our Milky Way galaxy blocks our view of distant objects, which, in this projection, lies predominantly along the edges of the image. http://photojournal.jpl.nasa.gov/catalog/PIA04252

Star formation quenching in green valley galaxies at 0.5 ≲ z ≲ 1.0 and constraints with galaxy morphologies

NASA Astrophysics Data System (ADS)

Nogueira-Cavalcante, J. P.; Gonçalves, T. S.; Menéndez-Delmestre, K.; Sheth, K.

2018-01-01

We calculate the star formation quenching time-scales in green valley galaxies at intermediate redshifts (z ∼ 0.5-1) using stacked zCOSMOS spectra of different galaxy morphological types: spheroidal, disc-like, irregular and merger, dividing disc-like galaxies further into unbarred, weakly barred and strongly barred, assuming a simple exponentially decaying star formation history model and based on the H δ absorption feature and the 4000 Å break. We find that different morphological types present different star formation quenching time-scales, reinforcing the idea that the galaxy morphology is strongly correlated with the physical processes responsible for quenching star formation. Our quantification of the star formation quenching time-scale indicates that discs have typical time-scales 60 per cent to five times longer than that of galaxies presenting spheroidal, irregular or merger morphologies. Barred galaxies, in particular, present the slowest transition time-scales through the green valley. This suggests that although secular evolution may ultimately lead to gas exhaustion in the host galaxy via bar-induced gas inflows that trigger star formation activity, secular agents are not major contributors in the rapid quenching of galaxies at these redshifts. Galaxy interaction, associated with the elliptical, irregular and merger morphologies, contributes, to a more significant degree, to the fast transition through the green valley at these redshifts. In light of previous works suggesting that both secular and merger processes are responsible for the star formation quenching at low redshifts, our results provide an explanation to the recent findings that star formation quenching happened at a faster pace at z ∼ 0.8.

ACTN3 R577X and ACE I/D gene variants influence performance in elite sprinters: a multi-cohort study.

PubMed

Papadimitriou, Ioannis D; Lucia, Alejandro; Pitsiladis, Yannis P; Pushkarev, Vladimir P; Dyatlov, Dmitry A; Orekhov, Evgeniy F; Artioli, Guilherme G; Guilherme, João Paulo L F; Lancha, Antonio H; Ginevičienė, Valentina; Cieszczyk, Pawel; Maciejewska-Karlowska, Agnieszka; Sawczuk, Marek; Muniesa, Carlos A; Kouvatsi, Anastasia; Massidda, Myosotis; Calò, Carla Maria; Garton, Fleur; Houweling, Peter J; Wang, Guan; Austin, Krista; Druzhevskaya, Anastasiya M; Astratenkova, Irina V; Ahmetov, Ildus I; Bishop, David J; North, Kathryn N; Eynon, Nir

2016-04-13

To date, studies investigating the association between ACTN3 R577X and ACE I/D gene variants and elite sprint/power performance have been limited by small cohorts from mixed sport disciplines, without quantitative measures of performance. To examine the association between these variants and sprint time in elite athletes. We collected a total of 555 best personal 100-, 200-, and 400-m times of 346 elite sprinters in a large cohort of elite Caucasian or African origin sprinters from 10 different countries. Sprinters were genotyped for ACTN3 R577X and ACE ID variants. On average, male Caucasian sprinters with the ACTN3 577RR or the ACE DD genotype had faster best 200-m sprint time than their 577XX (21.19 ± 0.53 s vs. 21.86 ± 0.54 s, p = 0.016) and ACE II (21.33 ± 0.56 vs. 21.93 ± 0.67 sec, p = 0.004) counterparts and only one case of ACE II, and no cases of ACTN3 577XX, had a faster 200-m time than the 2012 London Olympics qualifying (vs. 12 qualified sprinters with 577RR or 577RX genotype). Caucasian sprinters with the ACE DD genotype had faster best 400-m sprint time than their ACE II counterparts (46.94 ± 1.19 s vs. 48.50 ± 1.07 s, p = 0.003). Using genetic models we found that the ACTN3 577R allele and ACE D allele dominant model account for 0.92 % and 1.48 % of sprint time variance, respectively. Despite sprint performance relying on many gene variants and environment, the % sprint time variance explained by ACE and ACTN3 is substantial at the elite level and might be the difference between a world record and only making the final.

EVOLUTION IN THE H I GAS CONTENT OF GALAXY GROUPS: PRE-PROCESSING AND MASS ASSEMBLY IN THE CURRENT EPOCH

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hess, Kelley M.; Wilcots, Eric M., E-mail: hess@ast.uct.ac.za, E-mail: ewilcots@astro.wisc.edu

We present an analysis of the neutral hydrogen (H I) content and distribution of galaxies in groups as a function of their parent dark matter halo mass. The Arecibo Legacy Fast ALFA survey α.40 data release allows us, for the first time, to study the H I properties of over 740 galaxy groups in the volume of sky common to the Sloan Digital Sky Survey (SDSS) and ALFALFA surveys. We assigned ALFALFA H I detections a group membership based on an existing magnitude/volume-limited SDSS Data Release 7 group/cluster catalog. Additionally, we assigned group ''proximity' membership to H I detected objectsmore » whose optical counterpart falls below the limiting optical magnitude—thereby not contributing substantially to the estimate of the group stellar mass, but significantly to the total group H I mass. We find that only 25% of the H I detected galaxies reside in groups or clusters, in contrast to approximately half of all optically detected galaxies. Further, we plot the relative positions of optical and H I detections in groups as a function of parent dark matter halo mass to reveal strong evidence that H I is being processed in galaxies as a result of the group environment: as optical membership increases, groups become increasingly deficient of H I rich galaxies at their center and the H I distribution of galaxies in the most massive groups starts to resemble the distribution observed in comparatively more extreme cluster environments. We find that the lowest H I mass objects lose their gas first as they are processed in the group environment, and it is evident that the infall of gas rich objects is important to the continuing growth of large scale structure at the present epoch, replenishing the neutral gas supply of groups. Finally, we compare our results to those of cosmological simulations and find that current models cannot simultaneously predict the H I selected halo occupation distribution for both low and high mass halos.« less

The SCUBA-2 cosmology legacy survey: Ultraluminous star-forming galaxies in a z = 1.6 cluster

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smail, Ian; Swinbank, A. M.; Danielson, A. L. R.

2014-02-10

We analyze new SCUBA-2 submillimeter and archival SPIRE far-infrared imaging of a z = 1.62 cluster, Cl 0218.3–0510, which lies in the UKIRT Infrared Deep Sky Survey/Ultra-Deep Survey field of the SCUBA-2 Cosmology Legacy Survey. Combining these tracers of obscured star-formation activity with the extensive photometric and spectroscopic information available for this field, we identify 31 far-infrared/submillimeter-detected probable cluster members with bolometric luminosities ≳10{sup 12} L {sub ☉} and show that by virtue of their dust content and activity, these represent some of the reddest and brightest galaxies in this structure. We exploit ALMA submillimeter continuum observations, which cover onemore » of these sources, to confirm the identification of a SCUBA-2-detected ultraluminous star-forming galaxy in this structure. Integrating the total star-formation activity in the central region of the structure, we estimate that it is an order of magnitude higher (in a mass-normalized sense) than clusters at z ∼ 0.5-1. However, we also find that the most active cluster members do not reside in the densest regions of the structure, which instead host a population of passive and massive, red galaxies. We suggest that while the passive and active populations have comparable near-infrared luminosities at z = 1.6, M{sub H} ∼ –23, the subsequent stronger fading of the more active galaxies means that they will evolve into passive systems at the present day that are less luminous than the descendants of those galaxies that were already passive at z ∼ 1.6 (M{sub H} ∼ –20.5 and M{sub H} ∼ –21.5, respectively, at z ∼ 0). We conclude that the massive galaxy population in the dense cores of present-day clusters were already in place at z = 1.6 and that in Cl 0218.3–0510 we are seeing continuing infall of less extreme, but still ultraluminous, star-forming galaxies onto a pre-existing structure.« less

Energetics of the molecular gas in the H2 luminous radio galaxy 3C 326: Evidence for negative AGN feedback

NASA Astrophysics Data System (ADS)

Nesvadba, N. P. H.; Boulanger, F.; Salomé, P.; Guillard, P.; Lehnert, M. D.; Ogle, P.; Appleton, P.; Falgarone, E.; Pineau Des Forets, G.

2010-10-01

We present a detailed analysis of the gas conditions in the H2 luminous radio galaxy 3C 326 N at z ~ 0.1, which has a low star-formation rate (SFR ~ 0.07 M⊙ yr-1) in spite of a gas surface density similar to those in starburst galaxies. Its star-formation efficiency is likely a factor ~10-50 lower than those of ordinary star-forming galaxies. Combining new IRAM CO emission-line interferometry with existing Spitzer mid-infrared spectroscopy, we find that the luminosity ratio of CO and pure rotational H2 line emission is factors 10-100 lower than what is usually found. This suggests that most of the molecular gas is warm. The Na D absorption-line profile of 3C 326 N in the optical suggests an outflow with a terminal velocity of ~-1800 km s-1 and a mass outflow rate of 30-40 M⊙ yr-1, which cannot be explained by star formation. The mechanical power implied by the wind, of order 1043 erg s-1, is comparable to the bolometric luminosity of the emission lines of ionized and molecular gas. To explain these observations, we propose a scenario where a small fraction of the mechanical energy of the radio jet is deposited in the interstellar medium of 3C 326 N, which powers the outflow, and the line emission through a mass, momentum and energy exchange between the different gas phases of the ISM. Dissipation times are of order 107-8 yrs, similar or greater than the typical jet lifetime. Small ratios of CO and PAH surface brightnesses in another 7 H2 luminous radio galaxies suggest that a similar form of AGN feedback could be lowering star-formation efficiencies in these galaxies in a similar way. The local demographics of radio-loud AGN suggests that secular gas cooling in massive early-type galaxies of ≥1011 M⊙ could generally be regulated through a fundamentally similar form of “maintenance-phase” AGN feedback. Based on observations carried out with the IRAM Plateau de Bure Interferometer.

Integral field spectroscopy of a sample of nearby galaxies. II. Properties of the H ii regions

NASA Astrophysics Data System (ADS)

Sánchez, S. F.; Rosales-Ortega, F. F.; Marino, R. A.; Iglesias-Páramo, J.; Vílchez, J. M.; Kennicutt, R. C.; Díaz, A. I.; Mast, D.; Monreal-Ibero, A.; García-Benito, R.; Bland-Hawthorn, J.; Pérez, E.; González Delgado, R.; Husemann, B.; López-Sánchez, Á. R.; Cid Fernandes, R.; Kehrig, C.; Walcher, C. J.; Gil de Paz, A.; Ellis, S.

2012-10-01

We analyse the spectroscopic properties of thousands of H ii regions identified in 38 face-on spiral galaxies. All galaxies were observed out to 2.4 effective radii using integral field spectroscopy (IFS) over the wavelength range ~3700 to ~6900 Å. The near uniform sample has been assembled from the PPAK IFS Nearby Galaxy (PINGS) survey and a sample described in Paper I. We develop a new automatic procedure to detect H ii regions, based on the contrast of the Hα intensity maps extracted from the datacubes. Once detected, the algorithm provides us with the integrated spectra of each individual segmented region. In total, we derive good quality spectroscopic information for ~2600 independent H ii regions/complexes. This is by far the largest H ii region survey of its kind. Our selection criteria and the use of 3D spectroscopy guarantee that we cover the regions in an unbiased way. A well-tested automatic decoupling procedure has been applied to remove the underlying stellar population, deriving the main properties (intensity, dispersion and velocity) of the strongest emission lines in the considered wavelength range (covering from [O ii] λ3727 to [S ii] λ6731). A final catalogue of the spectroscopic properties of H ii regions has been created for each galaxy, which includes information on morphology, spiral structure, gaskinematics, and surface brightness of the underlying stellar population. In the current study, we focus on the understanding of the average properties of the H ii regions and their radial distributions. We find a significant change in the ionisation characteristics of H ii regions within r < 0.25 re due to contamination from sources with different ionising characteristics, as we discuss. We find that the gas-phase oxygen abundance and the Hα equivalent width present a negative and positive gradient, respectively. The distribution of slopes is statistically compatible with a random Gaussian distribution around the mean value, if the radial

Galaxy And Mass Assembly (GAMA): the galaxy stellar mass function to z = 0.1 from the r-band selected equatorial regions

NASA Astrophysics Data System (ADS)

Wright, A. H.; Robotham, A. S. G.; Driver, S. P.; Alpaslan, M.; Andrews, S. K.; Baldry, I. K.; Bland-Hawthorn, J.; Brough, S.; Brown, M. J. I.; Colless, M.; da Cunha, E.; Davies, L. J. M.; Graham, Alister W.; Holwerda, B. W.; Hopkins, A. M.; Kafle, P. R.; Kelvin, L. S.; Loveday, J.; Maddox, S. J.; Meyer, M. J.; Moffett, A. J.; Norberg, P.; Phillipps, S.; Rowlands, K.; Taylor, E. N.; Wang, L.; Wilkins, S. M.

2017-09-01

We derive the low-redshift galaxy stellar mass function (GSMF), inclusive of dust corrections, for the equatorial Galaxy And Mass Assembly (GAMA) data set covering 180 deg2. We construct the mass function using a density-corrected maximum volume method, using masses corrected for the impact of optically thick and thin dust. We explore the galactic bivariate brightness plane (M⋆-μ), demonstrating that surface brightness effects do not systematically bias our mass function measurement above 107.5 M⊙. The galaxy distribution in the M-μ plane appears well bounded, indicating that no substantial population of massive but diffuse or highly compact galaxies are systematically missed due to the GAMA selection criteria. The GSMF is fitted with a double Schechter function, with M^\\star =10^{10.78± 0.01± 0.20} M_{⊙}, φ ^\\star _1=(2.93± 0.40)× 10^{-3} h_{70}^3 Mpc-3, α1 = -0.62 ± 0.03 ± 0.15, φ ^\\star _2=(0.63± 0.10)× 10^{-3} h_{70}^3 Mpc-3 and α2 = -1.50 ± 0.01 ± 0.15. We find the equivalent faint end slope as previously estimated using the GAMA-I sample, although we find a higher value of M^\\star. Using the full GAMA-II sample, we are able to fit the mass function to masses as low as 107.5 M⊙, and assess limits to 106.5 M⊙. Combining GAMA-II with data from G10-COSMOS, we are able to comment qualitatively on the shape of the GSMF down to masses as low as 106 M⊙. Beyond the well-known upturn seen in the GSMF at 109.5, the distribution appears to maintain a single power-law slope from 109 to 106.5. We calculate the stellar mass density parameter given our best-estimate GSMF, finding Ω _\\star = 1.66^{+0.24}_{-0.23}± 0.97 h^{-1}_{70} × 10^{-3}, inclusive of random and systematic uncertainties.

Galaxy Clustering Topology in the Sloan Digital Sky Survey Main Galaxy Sample: A Test for Galaxy Formation Models

NASA Astrophysics Data System (ADS)

Choi, Yun-Young; Park, Changbom; Kim, Juhan; Gott, J. Richard, III; Weinberg, David H.; Vogeley, Michael S.; Kim, Sungsoo S.; SDSS Collaboration

2010-09-01

We measure the topology of the main galaxy distribution using the Seventh Data Release of the Sloan Digital Sky Survey, examining the dependence of galaxy clustering topology on galaxy properties. The observational results are used to test galaxy formation models. A volume-limited sample defined by Mr < -20.19 enables us to measure the genus curve with an amplitude of G = 378 at 6 h -1 Mpc smoothing scale, with 4.8% uncertainty including all systematics and cosmic variance. The clustering topology over the smoothing length interval from 6 to 10 h -1 Mpc reveals a mild scale dependence for the shift (Δν) and void abundance (AV ) parameters of the genus curve. We find substantial bias in the topology of galaxy clustering with respect to the predicted topology of the matter distribution, which varies with luminosity, morphology, color, and the smoothing scale of the density field. The distribution of relatively brighter galaxies shows a greater prevalence of isolated clusters and more percolated voids. Even though early (late)-type galaxies show topology similar to that of red (blue) galaxies, the morphology dependence of topology is not identical to the color dependence. In particular, the void abundance parameter AV depends on morphology more strongly than on color. We test five galaxy assignment schemes applied to cosmological N-body simulations of a ΛCDM universe to generate mock galaxies: the halo-galaxy one-to-one correspondence model, the halo occupation distribution model, and three implementations of semi-analytic models (SAMs). None of the models reproduces all aspects of the observed clustering topology; the deviations vary from one model to another but include statistically significant discrepancies in the abundance of isolated voids or isolated clusters and the amplitude and overall shift of the genus curve. SAM predictions of the topology color dependence are usually correct in sign but incorrect in magnitude. Our topology tests indicate that, in

78 FR 28825 - Commission Information Collection Activities (FERC-577); Comment Request

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-16

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. IC13-12-000] Commission Information Collection Activities (FERC-577); Comment Request AGENCY: Federal Energy Regulatory Commission... Act of 1995, 44 USC 3507(a)(1)(D), the Federal Energy Regulatory Commission (Commission or FERC) is...

Distribution and motions of atomic hydrogen in lenticular galaxies. X - The blue S0 galaxy NGC 5102

NASA Technical Reports Server (NTRS)

Van Woerden, H.; Van Driel, W.; Braun, R.; Rots, A. H.

1993-01-01

Results of the mapping of the blue gas-rich S0 galaxy NGC 5102 in the 21-cm H I line with a spatial resolution of 34 x 37 arcsec (delta(alpha) x Delta(delta)) and a velocity resolution of 12 km/s are presented. The H I distribution has a pronounced central depression of 1.9 kpc radius, and most of the H I is concentrated in a 3.6 kpc wide ring with an average radius of 3.7 kpc, assuming a distance of 4 Mpc for NGC 5102. The maximum azimuthally averaged H I surface density in the ring is 1.4 solar mass/sq pc, comparable to that found in other S0 galaxies. The HI velocity field is quite regular, showing no evidence for large-scale deviations from circular rotation, and the H I is found to rotate in the plane of the stellar disk. Both the H I mass/blue luminosity ratio and the radial H I distribution are similar to those in early-type spirals. The H I may be an old disk or it may have been acquired through capture of a gas-rich smaller galaxy. The recent starburst in the nuclear region, which gave the galaxy its blue color, may have been caused by partial radial collapse of the gas disk, or by infall of a gas-rich dwarf galaxy.

The redshift-space neighborhoods of 36 loose groups of galaxies. 1: The data

NASA Technical Reports Server (NTRS)

Ramella, Massimo; Geller, Margaret J.; Hurchra, John P.; Thorstensen, John R.

1995-01-01

We have selected 36 loose groups of galaxies (RGH89) with at least five members, and with mean redshift average value of CZ is greater than 3200 km/s. These groups all lie within the first two slices of the CfA redshift survey 8(sup h) less than or equal to alpha less than or equal to 17(sup h) and 26.5 deg less than or equal to delta less than or equal to 38.5 deg). For each of these groups, we define the redshift-space neighborhood as a region centered on the group coordinates and delimited by a circle of projected radius R(sub cir) = 1.5/h Mpc on the sky, and by a velocity interval delta (sub cz) = 3000 km/s. Here we give the redshifts of 334 galaxies in these redshift-space neighborhoods. For completeness, we also give the redshifts of the 232 original members. These data include 199 new redshifts. We demonstrate that these samples of fainter galaxies significantly increase the number of members.

Galaxy and Mass Assembly (GAMA): the GAMA galaxy group catalogue (G3Cv1)

NASA Astrophysics Data System (ADS)

Robotham, A. S. G.; Norberg, P.; Driver, S. P.; Baldry, I. K.; Bamford, S. P.; Hopkins, A. M.; Liske, J.; Loveday, J.; Merson, A.; Peacock, J. A.; Brough, S.; Cameron, E.; Conselice, C. J.; Croom, S. M.; Frenk, C. S.; Gunawardhana, M.; Hill, D. T.; Jones, D. H.; Kelvin, L. S.; Kuijken, K.; Nichol, R. C.; Parkinson, H. R.; Pimbblet, K. A.; Phillipps, S.; Popescu, C. C.; Prescott, M.; Sharp, R. G.; Sutherland, W. J.; Taylor, E. N.; Thomas, D.; Tuffs, R. J.; van Kampen, E.; Wijesinghe, D.

2011-10-01

Using the complete Galaxy and Mass Assembly I (GAMA-I) survey covering ˜142 deg2 to rAB= 19.4, of which ˜47 deg2 is to rAB= 19.8, we create the GAMA-I galaxy group catalogue (G3Cv1), generated using a friends-of-friends (FoF) based grouping algorithm. Our algorithm has been tested extensively on one family of mock GAMA lightcones, constructed from Λ cold dark matter N-body simulations populated with semi-analytic galaxies. Recovered group properties are robust to the effects of interlopers and are median unbiased in the most important respects. G3Cv1 contains 14 388 galaxy groups (with multiplicity ≥2), including 44 186 galaxies out of a possible 110 192 galaxies, implying ˜40 per cent of all galaxies are assigned to a group. The similarities of the mock group catalogues and G3Cv1 are multiple: global characteristics are in general well recovered. However, we do find a noticeable deficit in the number of high multiplicity groups in GAMA compared to the mocks. Additionally, despite exceptionally good local spatial completeness, G3Cv1 contains significantly fewer compact groups with five or more members, this effect becoming most evident for high multiplicity systems. These two differences are most likely due to limitations in the physics included of the current GAMA lightcone mock. Further studies using a variety of galaxy formation models are required to confirm their exact origin. The G3Cv1 catalogue will be made publicly available as and when the relevant GAMA redshifts are made available at .

Warm-hot gas in X-ray bright galaxy clusters and the H I-deficient circumgalactic medium in dense environments

NASA Astrophysics Data System (ADS)

Burchett, Joseph N.; Tripp, Todd M.; Wang, Q. Daniel; Willmer, Christopher N. A.; Bowen, David V.; Jenkins, Edward B.

2018-04-01

We analyse the intracluster medium (ICM) and circumgalactic medium (CGM) in seven X-ray-detected galaxy clusters using spectra of background quasi-stellar objects (QSOs) (HST-COS/STIS), optical spectroscopy of the cluster galaxies (MMT/Hectospec and SDSS), and X-ray imaging/spectroscopy (XMM-Newton and Chandra). First, we report a very low covering fraction of H I absorption in the CGM of these cluster galaxies, f_c = 25^{+25}_{-15} {per cent}, to stringent detection limits (N(H I) <1013 cm-2). As field galaxies have an H I covering fraction of ˜ 100 per cent at similar radii, the dearth of CGM H I in our data indicates that the cluster environment has effectively stripped or overionized the gaseous haloes of these cluster galaxies. Secondly, we assess the contribution of warm-hot (105-106 K) gas to the ICM as traced by O VI and broad Ly α (BLA) absorption. Despite the high signal-to-noise ratio of our data, we do not detect O VI in any cluster, and we only detect BLA features in the QSO spectrum probing one cluster. We estimate that the total column density of warm-hot gas along this line of sight totals to ˜ 3 per cent of that contained in the hot T > 107 K X-ray emitting phase. Residing at high relative velocities, these features may trace pre-shocked material outside the cluster. Comparing gaseous galaxy haloes from the low-density `field' to galaxy groups and high-density clusters, we find that the CGM is progressively depleted of H I with increasing environmental density, and the CGM is most severely transformed in galaxy clusters. This CGM transformation may play a key role in environmental galaxy quenching.

Gas kinematics in FIRE simulated galaxies compared to spatially unresolved H I observations

NASA Astrophysics Data System (ADS)

El-Badry, Kareem; Bradford, Jeremy; Quataert, Eliot; Geha, Marla; Boylan-Kolchin, Michael; Weisz, Daniel R.; Wetzel, Andrew; Hopkins, Philip F.; Chan, T. K.; Fitts, Alex; Kereš, Dušan; Faucher-Giguère, Claude-André

2018-06-01

The shape of a galaxy's spatially unresolved, globally integrated 21-cm emission line depends on its internal gas kinematics: galaxies with rotationally supported gas discs produce double-horned profiles with steep wings, while galaxies with dispersion-supported gas produce Gaussian-like profiles with sloped wings. Using mock observations of simulated galaxies from the FIRE project, we show that one can therefore constrain a galaxy's gas kinematics from its unresolved 21-cm line profile. In particular, we find that the kurtosis of the 21-cm line increases with decreasing V/σ and that this trend is robust across a wide range of masses, signal-to-noise ratios, and inclinations. We then quantify the shapes of 21-cm line profiles from a morphologically unbiased sample of ˜2000 low-redshift, H I-detected galaxies with Mstar = 107-11 M⊙ and compare to the simulated galaxies. At Mstar ≳ 1010 M⊙, both the observed and simulated galaxies produce double-horned profiles with low kurtosis and steep wings, consistent with rotationally supported discs. Both the observed and simulated line profiles become more Gaussian like (higher kurtosis and less-steep wings) at lower masses, indicating increased dispersion support. However, the simulated galaxies transition from rotational to dispersion support more strongly: at Mstar = 108-10 M⊙, most of the simulations produce more Gaussian-like profiles than typical observed galaxies with similar mass, indicating that gas in the low-mass simulated galaxies is, on average, overly dispersion supported. Most of the lower-mass-simulated galaxies also have somewhat lower gas fractions than the median of the observed population. The simulations nevertheless reproduce the observed line-width baryonic Tully-Fisher relation, which is insensitive to rotational versus dispersion support.

ACTN3 R577X Polymorphism and Neuromuscular Response to Resistance Training

PubMed Central

Gentil, Paulo; Pereira, Rinaldo W.; Leite, Tailce K.M.; Bottaro, Martim

2011-01-01

The R577X polymorphism at the ACTN3 gene has been associated with muscle strength, hypertrophy and athletic status. The X allele, which is associated with the absence of ACTN3 protein is supposed to impair performance of high force/velocity muscle contractions. The purpose of the present study was to investigate the association of the R577X polymorphism with the muscle response to resistance training in young men. One hundred forty one men performed two resistance training sessions per week for 11 weeks. Participants were tested for 1RM bench press, knee extensors peak torque, and knee extensors muscle thickness at baseline and after the training period. Genotyping was conducted using de DdeI restriction enzyme. Genotype distribution was 34.4% for RR, 47% for RX and 18.6% for the XX genotype. According to the results, the R577X polymorphism at the ACTN3 gene is not associated with baseline muscle strength or with the muscle strength response to resistance training. However, only carriers of the R allele showed increases in muscle thickness in response to training. Key points ACTN3 Genotype distribution in the present study was similar to others populations (34.4% for RR, 47% for RX, and 18.6% for the XX). The R577X polymorphism at the ACTN3 gene is not associated with baseline muscle strength or with the muscle strength response to resistance training. It appears that the R allele carriers respond better to muscle thickness gains in response to training. PMID:24149888

ACTN3 R577X Polymorphism and Neuromuscular Response to Resistance Training.

PubMed

Gentil, Paulo; Pereira, Rinaldo W; Leite, Tailce K M; Bottaro, Martim

2011-01-01

The R577X polymorphism at the ACTN3 gene has been associated with muscle strength, hypertrophy and athletic status. The X allele, which is associated with the absence of ACTN3 protein is supposed to impair performance of high force/velocity muscle contractions. The purpose of the present study was to investigate the association of the R577X polymorphism with the muscle response to resistance training in young men. One hundred forty one men performed two resistance training sessions per week for 11 weeks. Participants were tested for 1RM bench press, knee extensors peak torque, and knee extensors muscle thickness at baseline and after the training period. Genotyping was conducted using de DdeI restriction enzyme. Genotype distribution was 34.4% for RR, 47% for RX and 18.6% for the XX genotype. According to the results, the R577X polymorphism at the ACTN3 gene is not associated with baseline muscle strength or with the muscle strength response to resistance training. However, only carriers of the R allele showed increases in muscle thickness in response to training. Key pointsACTN3 Genotype distribution in the present study was similar to others populations (34.4% for RR, 47% for RX, and 18.6% for the XX).The R577X polymorphism at the ACTN3 gene is not associated with baseline muscle strength or with the muscle strength response to resistance training.It appears that the R allele carriers respond better to muscle thickness gains in response to training.

The ACTN3 R577X Polymorphism across Three Groups of Elite Male European Athletes

PubMed Central

Eynon, Nir; Ruiz, Jonatan R.; Femia, Pedro; Pushkarev, Vladimir P.; Cieszczyk, Pawel; Maciejewska-Karlowska, Agnieszka; Sawczuk, Marek; Dyatlov, Dmitry A.; Lekontsev, Evgeny V.; Kulikov, Leonid M.; Birk, Ruth

2012-01-01

The ACTN3 R577X polymorphism (rs1815739) is a strong candidate to influence elite athletic performance. Yet, controversy exists in the literature owing to between-studies differences in the ethnic background and sample size of the cohorts, the latter being usually low, which makes comparisons difficult. In this case:control genetic study we determined the association between elite athletic status and the ACTN3 R577X polymorphism within three cohorts of European Caucasian men, i.e. Spanish, Polish and Russian [633 cases (278 elite endurance and 355 power athletes), and 808 non-athletic controls]. The odds ratio (OR) of a power athlete harbouring the XX versus the RR genotype compared with sedentary controls was 0.54 [95% confidence interval (CI): 0.34–0.48; P = 0.006]. We also observed that the OR of an endurance athlete having the XX versus the RR genotype compared with power athletes was 1.88 (95%CI: 1.07–3.31; P = 0.028). In endurance athletes, the OR of a “world-class” competitor having the XX genotype versus the RR+RX genotype was 3.74 (95%CI: 1.08–12.94; P = 0.038) compared with those of a lower (“national”) competition level. No association (P>0.1) was noted between the ACTN3 R577X polymorphism and competition level (world-class versus national-level) in power athletes. Our data provide comprehensive support for the influence of the ACTN3 R577X polymorphism on elite athletic performance. PMID:22916217

The hELENa project - II. Abundance distribution trends of early-type galaxies: from dwarfs to giants

NASA Astrophysics Data System (ADS)

Sybilska, A.; Kuntschner, H.; van de Ven, G.; Vazdekis, A.; Falcón-Barroso, J.; Peletier, R. F.; Lisker, T.

2018-06-01

In this second paper of The role of Environment in shaping Low-mass Early-type Nearby galaxies (hELENa) series we study [Mg/Fe] abundance distribution trends of early-type galaxies (ETGs) observed with the Spectrographic Areal Unit for Research on Optical Nebulae integral field unit, spanning a wide range in mass and local environment densities: 20 low-mass early types (dEs) of Sybilska et al. and 258 massive early types (ETGs) of the ATLAS3D project, all homogeneously reduced and analysed. We show that the [Mg/Fe] ratios scale with velocity dispersion (σ) at fixed [Fe/H] and that they evolve with [Fe/H] along similar paths for all early types, grouped in bins of increasing local and global σ, as well as the second velocity moment Vrms, indicating a common inside-out formation pattern. We then place our dEs on the [Mg/Fe] versus [Fe/H] diagram of Local Group galaxies and show that dEs occupy the same region and show a similar trend line slope in the diagram as the high-metallicity stars of the Milky Way and the Large Magellanic Cloud. This finding extends the similar trend found for dwarf spheroidal versus dwarf irregular galaxies and supports the notion that dEs have evolved from late-type galaxies that have lost their gas at a point of their evolution, which likely coincided with them entering denser environments.

Fermi monitoring of radio-loud narrow-line Seyfert 1 galaxies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paliya, Vaidehi S.; Stalin, C. S.; Ravikumar, C. D., E-mail: vaidehi@iiap.res.in

2015-02-01

We present detailed analysis of the γ-ray flux variability and spectral properties of the five radio-loud narrow line Seyfert 1 (RL-NLSy1) galaxies, detected by the Large Area Telescope on board the Fermi Gamma-Ray Space Telescope, namely 1H 0323+342, SBS 0846+513, PMN J0948+0022, PKS 1502+036, and PKS 2004−447. The first three sources show significant flux variations, including the rapid variability of a few hours by 1H 0323+342. The average γ-ray spectrum of 1H 0323+342 and PMN J0948+0022 shows deviation from a simple power-law (PL) behavior, whereas the PL model gives a better fit for the other three sources. The spectra ofmore » 1H 0323+342, SBS 0846+513, and PMN J0948+0022, which are in low, flaring, and moderately active states, respectively, show significant curvature. Such curvature in the γ-ray spectrum of 1H 0323+342 and PMN J0948+0022 could be due to the emission region located inside the broad line region (BLR) where the primary mechanism of the γ-ray emission is inverse-Compton (IC) scattering of BLR photons occurring in the Klein–Nishina regime. The γ-ray emission of SBS 0846+513 is explained by IC scattering of dusty torus photons, which puts the emission region outside the BLR and thus under the Thomson regime. Therefore, the observed curvature of SBS 0846+513 could be intrinsic to the particle energy distribution. The presence of curvature in the γ-ray spectrum and flux variability amplitudes of some of the RL-NLSy1 galaxies suggests that these sources could be akin to low/moderate jet power flat spectrum radio quasars.« less

Bulgeless galaxies in the COSMOS field: environment and star formation evolution at z < 1

NASA Astrophysics Data System (ADS)

Grossi, Marco; Fernandes, Cristina A. C.; Sobral, David; Afonso, José; Telles, Eduardo; Bizzocchi, Luca; Paulino-Afonso, Ana; Matute, Israel

2018-03-01

Combining the catalogue of galaxy morphologies in the COSMOS field and the sample of H α emitters at redshifts z = 0.4 and z = 0.84 of the HiZELS survey, we selected ˜ 220 star-forming bulgeless systems (Sérsic index n ≤ 1.5) at both epochs. We present their star formation properties and we investigate their contribution to the star formation rate function (SFRF) and global star formation rate density (SFRD) at z < 1. For comparison, we also analyse H α emitters with more structurally evolved morphologies that we split into two classes according to their Sérsic index n: intermediate (1.5 < n ≤ 3) and bulge-dominated (n > 3). At both redshifts, the SFRF is dominated by the contribution of bulgeless galaxies and we show that they account for more than 60 per cent of the cosmic SFRD at z < 1. The decrease of the SFRD with redshift is common to the three morphological types, but it is stronger for bulge-dominated systems. Star-forming bulgeless systems are mostly located in regions of low to intermediate galaxy densities (Σ ˜ 1-4 Mpc-2) typical of field-like and filament-like environments and their specific star formation rates (sSFRs) do not appear to vary strongly with local galaxy density. Only few bulgeless galaxies in our sample have high (sSFR > 10-9 yr-1) and these are mainly low-mass systems. Above M* ˜ 1010 M⊙ bulgeless are evolving at a `normal' rate (10-9 yr-1 < sSFR < 10-10 yr-1) and in the absence of an external trigger (i.e. mergers/strong interactions) they might not be able to develop a central classical bulge.

Galaxy and Mass Assembly (GAMA): active galactic nuclei in pairs of galaxies

NASA Astrophysics Data System (ADS)

Gordon, Yjan A.; Owers, Matt S.; Pimbblet, Kevin A.; Croom, Scott M.; Alpaslan, Mehmet; Baldry, Ivan K.; Brough, Sarah; Brown, Michael J. I.; Cluver, Michelle E.; Conselice, Christopher J.; Davies, Luke J. M.; Holwerda, Benne W.; Hopkins, Andrew M.; Gunawardhana, Madusha L. P.; Loveday, Jonathan; Taylor, Edward N.; Wang, Lingyu

2017-03-01

There exist conflicting observations on whether or not the environment of broad- and narrow-line active galatic nuclei (AGN) differ and this consequently questions the validity of the AGN unification model. The high spectroscopic completeness of the Galaxy and Mass Assembly (GAMA) survey makes it ideal for a comprehensive analysis of the close environment of galaxies. To exploit this, and conduct a comparative analysis of the environment of broad- and narrow-line AGN within GAMA, we use a double-Gaussian emission line fitting method to model the more complex line profiles associated with broad-line AGN. We select 209 type 1 (I.e. unobscured), 464 type 1.5-1.9 (partially obscured), and 281 type 2 (obscured) AGN within the GAMA II data base. Comparing the fractions of these with neighbouring galaxies out to a pair separation of 350 kpc h-1 and Δz < 0.012 shows no difference between AGN of different type, except at separations less than 20 kpc h-1 where our observations suggest an excess of type 2 AGN in close pairs. We analyse the properties of the galaxies neighbouring our AGN and find no significant differences in colour or the star formation activity of these galaxies. Further to this, we find that Σ5 is also consistent between broad- and narrow-line AGN. We conclude that the observations presented here are consistent with AGN unification.

Neutral Gas Properties of Extremely Isolated Early-type Galaxies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ashley, Trisha; Marcum, Pamela M.; Fanelli, Michael N., E-mail: trisha.l.ashley@nasa.gov, E-mail: pamela.m.marcum@nasa.gov, E-mail: michael.n.fanelli@nasa.gov

We present the results of single-dish atomic hydrogen (H i) observations of six highly isolated early-type galaxies. These objects are a representative subset of galaxies previously studied at optical wavelengths and selected to be separated by at least 2.5 Mpc from companions brighter than M{sub V}  = −16.5 mag. Each galaxy was observed with a single pointing using the NRAO Green Bank Telescope L -band receiver. Five of these systems were strongly detected in H i. These five galaxies exhibit H i profiles with a range of properties: single Gaussian-like peaks, separate double peaks, and double horn-like profiles. The four bluestmore » galaxies ( B − V < 0.54) all contain significant gas with H i masses ranging from 1.1 × 10{sup 8} to 1.4 × 10{sup 9}.« less

A 16 deg2 survey of emission-line galaxies at z < 1.5 in HSC-SSP Public Data Release 1

NASA Astrophysics Data System (ADS)

Hayashi, Masao; Tanaka, Masayuki; Shimakawa, Rhythm; Furusawa, Hisanori; Momose, Rieko; Koyama, Yusei; Silverman, John D.; Kodama, Tadayuki; Komiyama, Yutaka; Leauthaud, Alexie; Lin, Yen-Ting; Miyazaki, Satoshi; Nagao, Tohru; Nishizawa, Atsushi J.; Ouchi, Masami; Shibuya, Takatoshi; Tadaki, Ken-ichi; Yabe, Kiyoto

2018-01-01

We present initial results from the Subaru Strategic Program (SSP) with Hyper Suprime-Cam (HSC) on a comprehensive survey of emission-line galaxies at z < 1.5 based on narrowband imaging. The first Public Data Release provides us with data from two narrowband filters, specifically NB816 and NB921 over 5.7 deg2 and 16.2 deg2 respectively. The 5 σ limiting magnitudes are 25.2 mag (UltraDeep layer, 1.4 deg2) and 24.8 mag (Deep layer, 4.3 deg2) for NB816, and 25.1 mag (UltraDeep, 2.9 deg2) and 24.6-24.8 mag (Deep, 13.3 deg2) for NB921. The wide-field imaging allows us to construct unprecedentedly large samples of 8054 H α emitters at z ≈ 0.25 and 0.40, 8656 [O III] emitters at z ≈ 0.63 and 0.84, and 16877 [O II] emitters at z ≈ 1.19 and 1.47. We map the cosmic web on scales out to about 50 comoving Mpc that includes galaxy clusters, identified by red sequence galaxies, located at the intersection of filamentary structures of star-forming galaxies. The luminosity functions of emission-line galaxies are measured with precision and are consistent with published studies. The wide field coverage of the data enables us to measure the luminosity functions up to brighter luminosities than previous studies. The comparison of the luminosity functions between the different HSC-SSP fields suggests that a survey volume of >5 × 105 Mpc3 is essential to overcome cosmic variance. Since the current data have not reached the full depth expected for the HSC-SSP, the color cut in i - NB816 or z - NB921 induces a bias towards star-forming galaxies with large equivalent widths, primarily seen in the stellar mass functions for the H α emitters at z ≈ 0.25-0.40. Even so, the emission-line galaxies clearly cover a wide range of luminosity, stellar mass, and environment, thus demonstrating the usefulness of the narrowband data from the HSC-SSP for investigating star-forming galaxies at z < 1.5.

The Star Formation Reference Survey - II. Activity demographics and host-galaxy properties for infrared-selected galaxies

NASA Astrophysics Data System (ADS)

Maragkoudakis, A.; Zezas, A.; Ashby, M. L. N.; Willner, S. P.

2018-04-01

We present activity demographics and host-galaxy properties of infrared-selected galaxies in the local Universe, using the representative Star Formation Reference Survey (SFRS). Our classification scheme is based on a combination of optical emission-line diagrams (BPT) and infrared (IR)-colour diagnostics. Using the weights assigned to the SFRS galaxies based on its parent sample, a far-IR-selected sample comprises 71 per cent H II galaxies, 13 per cent Seyferts, 3 per cent transition objects (TOs), and 13 per cent low-ionization nuclear emission-line regions (LINERs). For the SFRS H II galaxies, we derive nuclear star formation rates and gas-phase metallicities. We measure host-galaxy metallicities for all galaxies with available long-slit spectroscopy and abundance gradients for a subset of 12 face-on galaxies. The majority of H II galaxies show a narrow range of metallicities, close to solar, and flat metallicity profiles. Based on their host-galaxy and nuclear properties, the dominant ionizing source in the far-infrared selected TOs is star-forming activity. LINERs are found mostly in massive hosts (median of 1010.5 M⊙), median L(60 μm) = 109 L⊙, median dust temperatures of F60/F100 = 0.36, and median LH α surface density of 1040.2 erg s-1kpc-2, indicating older stellar populations as their main ionizing source rather than active galactic nucleus activity.

The molecular gas reservoir of 6 low-metallicity galaxies from the Herschel Dwarf Galaxy Survey. A ground-based follow-up survey of CO(1-0), CO(2-1), and CO(3-2)

NASA Astrophysics Data System (ADS)

Cormier, D.; Madden, S. C.; Lebouteiller, V.; Hony, S.; Aalto, S.; Costagliola, F.; Hughes, A.; Rémy-Ruyer, A.; Abel, N.; Bayet, E.; Bigiel, F.; Cannon, J. M.; Cumming, R. J.; Galametz, M.; Galliano, F.; Viti, S.; Wu, R.

2014-04-01

Context. Observations of nearby starburst and spiral galaxies have revealed that molecular gas is the driver of star formation. However, some nearby low-metallicity dwarf galaxies are actively forming stars, but CO, the most common tracer of this reservoir, is faint, leaving us with a puzzle about how star formation proceeds in these environments. Aims: We aim to quantify the molecular gas reservoir in a subset of 6 galaxies from the Herschel Dwarf Galaxy Survey with newly acquired CO data and to link this reservoir to the observed star formation activity. Methods: We present CO(1-0), CO(2-1), and CO(3-2) observations obtained at the ATNF Mopra 22-m, APEX, and IRAM 30-m telescopes, as well as [C ii] 157μm and [O i] 63μm observations obtained with the Herschel/PACS spectrometer in the 6 low-metallicity dwarf galaxies: Haro 11, Mrk 1089, Mrk 930, NGC 4861, NGC 625, and UM 311. We derived their molecular gas masses from several methods, including using the CO-to-H2 conversion factor XCO (both Galactic and metallicity-scaled values) and dust measurements. The molecular and atomic gas reservoirs were compared to the star formation activity. We also constrained the physical conditions of the molecular clouds using the non-LTE code RADEX and the spectral synthesis code Cloudy. Results: We detect CO in 5 of the 6 galaxies, including first detections in Haro 11 (Z ~ 0.4 Z⊙), Mrk 930 (0.2 Z⊙), and UM 311 (0.5 Z⊙), but CO remains undetected in NGC 4861 (0.2 Z⊙). The CO luminosities are low, while [C ii] is bright in these galaxies, resulting in [C ii]/CO(1-0) ≥ 10 000. Our dwarf galaxies are in relatively good agreement with the Schmidt-Kennicutt relation for total gas. They show short molecular depletion timescales, even when considering metallicity-scaled XCO factors. Those galaxies are dominated by their H i gas, except Haro 11, which has high star formation efficiency and is dominated by ionized and molecular gas. We determine the mass of each ISM phase in

Large-scale environments of narrow-line Seyfert 1 galaxies

NASA Astrophysics Data System (ADS)

Järvelä, E.; Lähteenmäki, A.; Lietzen, H.; Poudel, A.; Heinämäki, P.; Einasto, M.

2017-09-01

Studying large-scale environments of narrow-line Seyfert 1 (NLS1) galaxies gives a new perspective on their properties, particularly their radio loudness. The large-scale environment is believed to have an impact on the evolution and intrinsic properties of galaxies, however, NLS1 sources have not been studied in this context before. We have a large and diverse sample of 1341 NLS1 galaxies and three separate environment data sets constructed using Sloan Digital Sky Survey. We use various statistical methods to investigate how the properties of NLS1 galaxies are connected to the large-scale environment, and compare the large-scale environments of NLS1 galaxies with other active galactic nuclei (AGN) classes, for example, other jetted AGN and broad-line Seyfert 1 (BLS1) galaxies, to study how they are related. NLS1 galaxies reside in less dense environments than any of the comparison samples, thus confirming their young age. The average large-scale environment density and environmental distribution of NLS1 sources is clearly different compared to BLS1 galaxies, thus it is improbable that they could be the parent population of NLS1 galaxies and unified by orientation. Within the NLS1 class there is a trend of increasing radio loudness with increasing large-scale environment density, indicating that the large-scale environment affects their intrinsic properties. Our results suggest that the NLS1 class of sources is not homogeneous, and furthermore, that a considerable fraction of them are misclassified. We further support a published proposal to replace the traditional classification to radio-loud, and radio-quiet or radio-silent sources with a division into jetted and non-jetted sources.

Tomographic intensity mapping versus galaxy surveys: observing the Universe in H α emission with new generation instruments

NASA Astrophysics Data System (ADS)

Silva, B. Marta; Zaroubi, Saleem; Kooistra, Robin; Cooray, Asantha

2018-04-01

The H α line emission is an important probe for a number of fundamental quantities in galaxies, including their number density, star formation rate (SFR), and overall gas content. A new generation of low-resolution intensity mapping (IM) probes, e.g. SPHEREx and CDIM, will observe galaxies in H α emission over a large fraction of the sky from the local Universe till a redshift of z ˜ 6 - 10, respectively. This will also be the target line for observations by the high-resolution Euclid and WFIRST instruments in the z ˜ 0.7-2 redshift range. In this paper, we estimate the intensity and power spectra of the H α line in the z ˜ 0-5 redshift range using observed line luminosity functions (LFs), when possible, and simulations, otherwise. We estimate the significance of our predictions by accounting for the modelling uncertainties (e.g. SFR, extinction, etc.) and observational contamination. We find that IM surveys can make a statistical detection of the full H α emission between z ˜ 0.8 and 5. Moreover, we find that the high-frequency resolution and the sensitivity of the planned CDIM surveys allow for the separation of H α emission from several interloping lines. We explore ways to use the combination of these line intensities to probe galaxy properties. As expected, our study indicates that galaxy surveys will only detect bright galaxies that contribute up to a few per cent of the overall H α intensity. However, these surveys will provide important constraints on the high end of the H α LF and put strong constraints on the active galactic nucleus LF.

ACTN3 R577X Genotypes Associate with Class II and Deep Bite Malocclusions

PubMed Central

Zebrick, Brian; Teeramongkolgul, Teesit; Nicot, Romain; Horton, Michael J.; Raoul, Gwenael; Ferri, Joel; Vieira, Alexandre R.; Sciote, James J.

2014-01-01

Introduction α-actinins are myofibril anchor proteins which influence contractile properties of skeletal muscle. ACTN2 is expressed in slow type I and fast type II fibers whereas ACTN3 is expressed only in fast fibers. ACTN3 homozygosity for the 577X stop codon (i.e. changing 577RR to 577XX - the R577X polymorphism) results in the absence of α-actinin-3 in about 18% of Europeans, diminished fast contractile ability, enhanced endurance performance and reduced bone mass or bone mineral density. We have examined ACTN3 expression and genetic variation in masseter muscle of orthognathic surgery patients to determine genotype associations with malocclusion. Methods Clinical information, masseter muscle biopsies and saliva samples were obtained from 60 subjects. Genotyping for ACTN3 SNPs, RT-PCR quantitation of muscle gene message and muscle morphometric fiber type properties were compared to determine statistical differences between genotype and phenotype. Results Muscle mRNA expression level was significantly different for ACTN3 SNP genotypes (p<0.01). The frequency of ACTN3 genotypes was significantly different for sagittal and vertical classifications of malocclusion with the clearest association being elevated 577XX genotype in skeletal class II malocclusion (p = 0.003). This genotype also resulted in significantly smaller diameter of fast type II fibers in masseter muscle (p = 0.002). Conclusion ACTN3 577XX is overrepresented in skeletal class II malocclusion, suggesting a biologic influence during bone growth. ACTN3 577XX is underrepresented in deep bite malocclusion, suggesting muscle differences contribute to variations in vertical facial dimensions. PMID:25439211

THE CO-TO-H{sub 2} CONVERSION FACTOR AND DUST-TO-GAS RATIO ON KILOPARSEC SCALES IN NEARBY GALAXIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sandstrom, K. M.; Walter, F.; Leroy, A. K.

2013-11-01

We present ∼kiloparsec spatial resolution maps of the CO-to-H{sub 2} conversion factor (α{sub CO}) and dust-to-gas ratio (DGR) in 26 nearby, star-forming galaxies. We have simultaneously solved for α{sub CO} and the DGR by assuming that the DGR is approximately constant on kiloparsec scales. With this assumption, we can combine maps of dust mass surface density, CO-integrated intensity, and H I column density to solve for both α{sub CO} and the DGR with no assumptions about their value or dependence on metallicity or other parameters. Such a study has just become possible with the availability of high-resolution far-IR maps frommore » the Herschel key program KINGFISH, {sup 12}CO J = (2-1) maps from the IRAM 30 m large program HERACLES, and H I 21 cm line maps from THINGS. We use a fixed ratio between the (2-1) and (1-0) lines to present our α{sub CO} results on the more typically used {sup 12}CO J = (1-0) scale and show using literature measurements that variations in the line ratio do not affect our results. In total, we derive 782 individual solutions for α{sub CO} and the DGR. On average, α{sub CO} = 3.1 M{sub ☉} pc{sup –2} (K km s{sup –1}){sup –1} for our sample with a standard deviation of 0.3 dex. Within galaxies, we observe a generally flat profile of α{sub CO} as a function of galactocentric radius. However, most galaxies exhibit a lower α{sub CO} value in the central kiloparsec—a factor of ∼2 below the galaxy mean, on average. In some cases, the central α{sub CO} value can be factors of 5-10 below the standard Milky Way (MW) value of α{sub CO,{sub MW}} = 4.4 M{sub ☉} pc{sup –2} (K km s{sup –1}){sup –1}. While for α{sub CO} we find only weak correlations with metallicity, the DGR is well-correlated with metallicity, with an approximately linear slope. Finally, we present several recommendations for choosing an appropriate α{sub CO} for studies of nearby galaxies.« less

The Metallicity Dependence of the CO → H2 Conversion Factor in z >= 1 Star-forming Galaxies

NASA Astrophysics Data System (ADS)

Genzel, R.; Tacconi, L. J.; Combes, F.; Bolatto, A.; Neri, R.; Sternberg, A.; Cooper, M. C.; Bouché, N.; Bournaud, F.; Burkert, A.; Comerford, J.; Cox, P.; Davis, M.; Förster Schreiber, N. M.; Garcia-Burillo, S.; Gracia-Carpio, J.; Lutz, D.; Naab, T.; Newman, S.; Saintonge, A.; Shapiro, K.; Shapley, A.; Weiner, B.

2012-02-01

We use the first systematic samples of CO millimeter emission in z >= 1 ''main-sequence'' star-forming galaxies to study the metallicity dependence of the conversion factor αCO, from CO line luminosity to molecular gas mass. The molecular gas depletion rate inferred from the ratio of the star formation rate (SFR) to CO luminosity, is ~1 Gyr-1 for near-solar metallicity galaxies with stellar masses above M S ~ 1011 M ⊙. In this regime, the depletion rate does not vary more than a factor of two to three as a function of molecular gas surface density or redshift between z ~ 0 and 2. Below M S the depletion rate increases rapidly with decreasing metallicity. We argue that this trend is not caused by starburst events, by changes in the physical parameters of the molecular clouds, or by the impact of the fundamental-metallicity-SFR-stellar mass relation. A more probable explanation is that the conversion factor is metallicity dependent and that star formation can occur in ''CO-dark'' gas. The trend is also expected theoretically from the effect of enhanced photodissociation of CO by ultraviolet radiation at low metallicity. From the available z ~ 0 and z ~ 1-3 samples we constrain the slope of the log(αCO)-log (metallicity) relation to range between -1 and -2, fairly insensitive to the assumed slope of the gas-SFR relation. Because of the lower metallicities near the peak of the galaxy formation activity at z ~ 1-2 compared to z ~ 0, we suggest that molecular gas masses estimated from CO luminosities have to be substantially corrected upward for galaxies below M S. Based on observations with the Plateau de Bure millimetre interferometer, operated by the Institute for Radio Astronomy in the Millimetre Range (IRAM), which is funded by a partnership of INSU/CNRS (France), MPG (Germany), and IGN (Spain).

LOW CO LUMINOSITIES IN DWARF GALAXIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schruba, Andreas; Walter, Fabian; Sandstrom, Karin

2012-06-15

We present maps of {sup 12}COJ = 2-1 emission covering the entire star-forming disks of 16 nearby dwarf galaxies observed by the IRAM HERACLES survey. The data have 13'' angular resolution, {approx}250 pc at our average distance of D = 4 Mpc, and sample the galaxies by 10-1000 resolution elements. We apply stacking techniques to perform the first sensitive search for CO emission in dwarf galaxies outside the Local Group ranging from individual lines of sight, stacking over IR-bright regions of embedded star formation, and stacking over the entire galaxy. We detect five galaxies in CO with total CO luminositiesmore » of L{sub CO2-1} = (3-28) Multiplication-Sign 10{sup 6} K km s{sup -1} pc{sup 2}. The other 11 galaxies remain undetected in CO even in the stacked images and have L{sub CO2-1} {approx}< (0.4-8) Multiplication-Sign 10{sup 6} K km s{sup -1} pc{sup 2}. We combine our sample of dwarf galaxies with a large sample of spiral galaxies from the literature to study scaling relations of L{sub CO} with M{sub B} and metallicity. We find that dwarf galaxies with metallicities of Z Almost-Equal-To 1/2-1/10 Z{sub Sun} have L{sub CO} of 2-4 orders of magnitude smaller than massive spiral galaxies and that their L{sub CO} per unit L{sub B} is 1-2 orders of magnitude smaller. A comparison with tracers of star formation (FUV and 24 {mu}m) shows that L{sub CO} per unit star formation rate (SFR) is 1-2 orders of magnitude smaller in dwarf galaxies. One possible interpretation is that dwarf galaxies form stars much more efficiently: we argue that the low L{sub CO}/SFR ratio is due to the fact that the CO-to-H{sub 2} conversion factor, {alpha}{sub CO}, changes significantly in low-metallicity environments. Assuming that a constant H{sub 2} depletion time of {tau}{sub dep} = 1.8 Gyr holds in dwarf galaxies (as found for a large sample of nearby spirals) implies {alpha}{sub CO} values for dwarf galaxies with Z Almost-Equal-To 1/2-1/10 Z{sub Sun} that are more than one order of

QSO Lyalpha Absorption Lines in Galaxy Superclusters and Voids

NASA Astrophysics Data System (ADS)

Stocke, J. T.; Shull, J. M.; Penton, S.; Burks, G.; Donahue, M.

1993-12-01

We have used the Hubble Space Telescope (HST) Goddard High Resolution Spectrograph (GHRS) to search for Lyalpha absorption clouds in nearby galaxy voids (cz <= 10,000 km s(-1) ). Thus far, we have obtained GHRS spectra (G160M, 1225 -- 1255 Angstroms, 0.25 Angstroms resolution) of three very bright Active Galactic Nuclei, Mrk 501, I Zw I, and Mrk 335, at V <= 14.5. We find 4 probable (4.0 sigma - 4.5 sigma ) and 4 definite (5 sigma - 16 sigma ) Lyalpha absorption lines, with equivalent widths W_λ = 50 - 200 m Angstroms, corresponding to column densities N(H I) = 10(13) -- 10(14) cm(-2) , assuming a typical Doppler parameter of b = 25 km s(-1) . Based on an updated version of the CfA redshift survey (Huchra and Clemens, private communication), most of these Lyalpha systems appear to be associated with supercluster - sized ``strings'' of galaxies similar to the ``Great Wall''. Toward Mrk 501, the nearest bright galaxy at the redshift of the strongest (200 m Angstroms) Lyalpha cloud lies 500 h75(-1) kpc off the line of sight. Models of H I disks exposed to the intergalactic ionizing radiation field (Dove & Shull 1994, ApJ, 423, in press) show that the N(H I) = 10(13) cm(-2) contour in a typical spiral galaxy is reached at 100 kpc radial extent. Thus, the Lyalpha absorbers associated with galaxy-string systems may be the result of H I in an extended halo, in dwarf satellite galaxies (M_B > -15), or in tidally-stripped gas. Most importantly for cosmological origins of baryons, one (4.3 sigma ) Lyalpha absorption line in the spectrum of Mrk 501 lies within the galaxy void in the foreground of the ``Great Wall''. The nearest bright galaxy, to a level M_B <= -18.5 for H_0 = 75 km s(-1) Mpc(-1) , is more than 5 Mpc away. A pencil-beam survey of faint galaxies to M_B = -16.0 finds no galaxy within 100 h75(-1) kpc of the line of sight, at or near the absorber redshift.

Are Narrow Line Seyfert 1 Galaxies Viewed Pole-on?

DTIC Science & Technology

2011-04-01

0.2’’ respectively. Figure 1 displays the position of each slit over a Barbosa et al. (2009) GMOS IFU image of the [S III] flux (which originates...C. Winge, H. Schmitt: Gemini/ GMOS IFU gas velocity ’tomography’ of the narrow line region of nearby active galaxies, MNRAS, 396 (2009) 2. [2] D...1995) 81. 4 P o S ( N L S 1 ) 0 5 0 Are NLS1s Pole-on? Travis C. Fischer 5 Figure 1: NGC 4051 GMOS IFU image showing integrated [SIII] flux

31 CFR 500.577 - Authorization of bank transactions with respect to Vietnam by certain international organizations.

Code of Federal Regulations, 2010 CFR

2010-07-01

... with respect to Vietnam by certain international organizations. 500.577 Section 500.577 Money and... Licensing Policy § 500.577 Authorization of bank transactions with respect to Vietnam by certain... reference to Vietnam are authorized. Example: A transfer to Vietnam or a Vietnamese national of funds from...

Diffraction-limited 577 nm true-yellow laser by frequency doubling of a tapered diode laser

NASA Astrophysics Data System (ADS)

Christensen, Mathias; Vilera, Mariafernanda; Noordegraaf, Danny; Hansen, Anders K.; Buß, Thomas; Jensen, Ole B.; Skovgaard, Peter M. W.

2018-02-01

A wide range of laser medical treatments are based on coagulation of blood by absorption of the laser radiation. It has, therefore, always been a goal of these treatments to maximize the ratio of absorption in the blood to that in the surrounding tissue. For this purpose lasers at 577 nm are ideal since this wavelength is at the peak of the absorption in oxygenated hemoglobin. Furthermore, 577 nm has a lower absorption in melanin when compared to green wavelengths (515 - 532 nm), giving it an advantage when treating at greater penetration depth. Here we present a laser system based on frequency doubling of an 1154 nm Distributed Bragg Reflector (DBR) tapered diode laser, emitting 1.1 W of single frequency and diffraction limited yellow light at 577 nm, corresponding to a conversion efficiency of 30.5%. The frequency doubling is performed in a single pass configuration using a cascade of two bulk non-linear crystals. The system is power stabilized over 10 hours with a standard deviation of 0.13% and the relative intensity noise is measured to be 0.064 % rms.

ACTN3 R577X polymorphism and performance phenotypes in young Chinese male soldiers.

PubMed

Shang, Xuya; Zhang, Fu; Zhang, Li; Huang, Changlin

2012-01-01

Alpha-actinin-3 (ACTN3) is absent in 18% of healthy Caucasian individuals owing to homozygosity for a premature stop codon (X) at amino acid 577 (rs1815739). Previous studies have shown a strong association between ACTN3 genotype and human athletic performance. In a study of 452 young Chinese male soldiers, we examined the distribution of ACTN3 genotypes and alleles and analysed the association between ACTN3 genotypes and athletic performance. We found that the frequencies of the ACTN3 R577X genotype (RR 39.8%, RX 43.4%, and XX 16.8%) and R577X allele (R 61.5%, X 38.5%) in young Chinese males were not significantly different from those in Caucasians. We only observed a significant association (P = 0.025) between ACTN3 R577X genotypes and grip strength. Participants with the XX genotype displayed significantly lower handgrip strength than individuals with the RR genotype (P = 0.021), but the difference between XX and RX means (P = 0.258) and that between RR and RX means (P = 0.42) was not significant. We did not observe a strong association between the ACTN3 R577X genotypes and sprint phenotypes or endurance phenotypes. In conclusion, our results indicate that the ACTN3 R577X polymorphism is most strongly associated with grip strength in young Chinese male soldiers.

ACTN3 R577X genotype and athletic performance in a large cohort of Japanese athletes.

PubMed

Kikuchi, Naoki; Miyamoto-Mikami, Eri; Murakami, Haruka; Nakamura, Tomohiro; Min, Seok-Ki; Mizuno, Masuhiko; Naito, Hisashi; Miyachi, Motohiko; Nakazato, Koichi; Fuku, Noriyuki

2016-09-01

Recent meta-analyses of the literature confirmed the association between the RR+RX genotype of the ACTN3 R577X polymorphism and elite sprint/power athletic status in Europeans but not in Asians and Africans, while the association between the R577X genotype and elite endurance athlete status is less convincing. The aim of the present study was to investigate the association between the ACTN3 R577X genotype and elite athlete status in a large Asian (Japanese) cohort of track and field athletes. One-thousand fifty-seven Japanese track and field athletes (627 sprint/power athletes and 430 endurance athletes) and 810 Japanese controls were genotyped for the ACTN3 R577X polymorphism (rs1815739) by using the TaqMan® SNP Genotyping Assay. Elite sprint/power athletes had a higher frequency of the RR+RX genotype than the controls (OR: 1.59, 95% CI: 1.16-2.18; P = .003). A significant linear correlation was found between the RR + RX genotype and athlete status (i.e. regional < national < international) in sprint/power athletes (regional: 71%, national: 81%, international: 84%; P = .001 for trend) and long-distance runners (regional: 65%, national: 72%, international: 82%; P = .030 for trend). The data obtained for this large Asian (Japanese) cohort of track and field athletes served to confirm the association between the RR + RX genotype of the ACTN3 R577X polymorphism and elite sprint/power athlete status and also the association between the ACTN3 RR + RX genotype and long-distance running athletic status.

The distant red galaxy neighbour population of 1 <~ z <~ 2 QSOs and optically obscured sources

NASA Astrophysics Data System (ADS)

Bornancini, Carlos G.; García Lambas, Diego

2007-05-01

We study the distant red galaxy (DRG; J - Ks > 2.3) neighbour population of quasi-stellar objects (QSOs) selected from the Sloan Digital Sky Survey (SDSS) in the redshift range 1 <~ z <~ 2. We perform a similar analysis for optically obscured active galactic nuclei (AGNs; i.e. with a limiting magnitude I > 24) detected in the mid-infrared (24 μm) with the Spitzer Space Telescope and a mean redshift z ~ 2.2 in the Flamingos Extragalactic Survey (FLAMEX). Both QSOs and obscured AGN target samples cover 4.7 deg2 in the same region of the sky. We find a significant difference in the environment of these two target samples. Neighbouring galaxies close to QSOs tend to be bluer than galaxies in optically obscured source environments. We also present results on the cross-correlation function of DRGs around QSOs and optically faint mid-infrared sources. The corresponding correlation length obtained for the QSO sample targets is r0 = 5.4 +/- 1.6 Mpc h-1 and a slope of γ = 1.94 +/- 0.10. For the optically obscured galaxy sample, we find r0 = 8.9 +/- 1.4 Mpc h-1 and a slope of γ = 2.27 +/- 0.20. These results indicate that optically faint obscured sources are located in denser environment of evolved red galaxies compared to QSOs. Based on observations and/or data products by the Flamingos Extragalactic Survey. FLAMINGOS was designed and constructed by the IR instrumentation group (PI: R. Elston) at the University of Florida, Department of Astronomy, with support from NSF grant AST97-31180 and Kitt Peak National Observatory. E-mail: bornancini@oac.uncor.edu

Observational constraints on disc galaxy formation

NASA Astrophysics Data System (ADS)

Syer, D.; Mao, Shude; Mo, H. J.

1999-04-01

We use data from the literature to constrain theoretical models of galaxy formation. We show how to calculate the dimensionless spin parameter lambda of the haloes of disc galaxies, and we compare the distribution of lambda with that observed in cosmological N-body simulations. The agreement is excellent, which provides strong support for the hierarchical picture of galaxy formation. Assuming only that the radial surface density distribution of discs is exponential, we estimate crudely the maximum-disc mass-to-light ratio in the I band, and obtain < Upsilon_I> <~ 3.56 h, for a Hubble constant of 100 h km s^-1 Mpc^-1. We discuss this result and its limitations in relation to other independent determinations of Upsilon_I. We also define a dimensionless form of the Tully-Fisher relation, and use it to derive a value of the baryon fraction in disc galaxies; the median value is m_d = 0.084 (Upsilon_I3.56 h). Assuming that the gas fraction in galactic haloes is at most as large as that in clusters, we also conclude that < Upsilon_I> <~ 2.56 h^-1/2.

Unveiling the Galaxy Population at 1.3 < z < 4: the HUDF05 NICMOS Parallel Fields

NASA Technical Reports Server (NTRS)

Petty, Sara M.; deMello, Duilia F.; Wiklind, Tomy; Gardner, Jonathan P.; Mountain, Matt

2010-01-01

Using the Hubble Ultra Deep Field Near Infrared Camera and Multi-Object Spectrometer (HUDF-NICMOS) UDF05 parallel fields, we cross-matched 301 out of 630 galaxies with the ACS filters V606 and z850, NICMOS filters J110 and H160, and Spitzer IRAC filters at 3.6, 4.5, 5.8 , and 8.0 (mu)m. We modeled the spectral energy distributions (SEDs) to estimate: photometric redshifts, dust extinction, stellar mass, bolometric luminosity, starburst age and metallicity. To validate the photometric redshifts, comparisons with 16 spectroscopic redshifts give 75% within Delta < 0.2, which agrees with the sensitivities expected from the Balmer-break in our dataset. Five parallel fields observed by NICMOS have sensitivities in the H160-band of 80% at mAB = 25.4 and 50% at mAB = 26.7. Because the sample is H160-band selected, it is sensitive to stellar mass rather than UV luminosities. We also use Monte Carlo simulations to determine that the parameters from the best-fit SEDs are robust for the redshift ranges z > or approx. 1.3. Based on the robustness of the photometric redshifts, we analyze a subsample of the 301 galaxies at 1.3 < or = z < or = 2 (35 objects) and 3 < or = z < or = 4 (31 objects) and determine that L(BoI) and the star formation rate increase significantly from z approx. 1.5 to 4. The Balmer decrement is indicative of more evolved galaxies, and at high redshifts, they serve as records of some of the first galaxies. Therefore, the galaxies in this sample are great candidates for future surveys with the James Webb Space Telescope and Atacama Large Millimeter Array.

Narrow-line Seyfert 1 galaxies at hard X-rays

NASA Astrophysics Data System (ADS)

Panessa, F.; de Rosa, A.; Bassani, L.; Bazzano, A.; Bird, A.; Landi, R.; Malizia, A.; Miniutti, G.; Molina, M.; Ubertini, P.

2011-11-01

Narrow-line Seyfert 1 (NLSy1) galaxies are a peculiar class of type 1 active galactic nuclei (broad-line Seyfert 1 galaxies, hereinafter BLSy1). The X-ray properties of individual objects belonging to this class are often extreme and associated with accretion at high Eddington ratios. Here, we present a study on a sample of 14 NLSy1 galaxies selected at hard X-rays (>20 keV) from the fourth INTEGRAL/IBIS catalogue. The 20-100 keV IBIS spectra show hard-X-ray photon indices flatly distributed (Γ20-100 keV ranging from ˜1.3 to ˜3.6) with an average value of <Γ20-100 keV>= 2.3 ± 0.7, compatible with a sample of hard-X-ray BLSy1 average slopes. Instead, NLSy1 galaxies show steeper spectral indices with respect to BLSy1 galaxies when broad-band spectra are considered. Indeed, we combine XMM-Newton and Swift/XRT with INTEGRAL/IBIS data sets to obtain a wide energy spectral coverage (0.3-100 keV). A constraint on the high energy cut-off and on the reflection component is achieved only in one source, SWIFT J2127.4+5654 (Ecut-off˜ 50 keV, R= 1.0+0.5- 0.4). Hard-X-ray-selected NLSy1 galaxies do not display particularly strong soft excess emission, while absorption fully or partially covering the continuum is often measured as well as Fe line emission features. Variability is a common trait in this sample, both at X-rays and at hard X-rays. The fraction of NLSy1 galaxies in the hard-X-ray sky is likely to be ˜15 per cent, in agreement with estimates derived in optically selected NLSy1 samples. We confirm the association of NLSy1 galaxies with small black hole masses with a peak at 107 M⊙ in the distribution; however, hard-X-ray NLSy1 galaxies seem to occupy the lower tail of the Eddington ratio distribution of classical NLSy1 galaxies. Based on observations obtained with the INTEGRAL/IBIS, XMM-Newton and Swift/XRT.

MULTIDARK-GALAXIES: data release and first results

NASA Astrophysics Data System (ADS)

Knebe, Alexander; Stoppacher, Doris; Prada, Francisco; Behrens, Christoph; Benson, Andrew; Cora, Sofia A.; Croton, Darren J.; Padilla, Nelson D.; Ruiz, Andrés N.; Sinha, Manodeep; Stevens, Adam R. H.; Vega-Martínez, Cristian A.; Behroozi, Peter; Gonzalez-Perez, Violeta; Gottlöber, Stefan; Klypin, Anatoly A.; Yepes, Gustavo; Enke, Harry; Libeskind, Noam I.; Riebe, Kristin; Steinmetz, Matthias

2018-03-01

We present the public release of the MULTIDARK-GALAXIES: three distinct galaxy catalogues derived from one of the Planck cosmology MULTIDARK simulations (i.e. MDPL2, with a volume of (1 h-1 Gpc)3 and mass resolution of 1.5 × 109 h-1 M⊙) by applying the semi-analytic models GALACTICUS, SAG, and SAGE to it. We compare the three models and their conformity with observational data for a selection of fundamental properties of galaxies like stellar mass function, star formation rate, cold gas fractions, and metallicities - noting that they sometimes perform differently reflecting model designs and calibrations. We have further selected galaxy subsamples of the catalogues by number densities in stellar mass, cold gas mass, and star formation rate in order to study the clustering statistics of galaxies. We show that despite different treatment of orphan galaxies, i.e. galaxies that lost their dark-matter host halo due to the finite-mass resolution of the N-body simulation or tidal stripping, the clustering signal is comparable, and reproduces the observations in all three models - in particular when selecting samples based upon stellar mass. Our catalogues provide a powerful tool to study galaxy formation within a volume comparable to those probed by ongoing and future photometric and redshift surveys. All model data consisting of a range of galaxy properties - including broad-band SDSS magnitudes - are publicly available.

Distance determinations to shield galaxies from Hubble space telescope imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

McQuinn, Kristen B. W.; Skillman, Evan D.; Cannon, John M.

The Survey of H I in Extremely Low-mass Dwarf (SHIELD) galaxies is an ongoing multi-wavelength program to characterize the gas, star formation, and evolution in gas-rich, very low-mass galaxies. The galaxies were selected from the first ∼10% of the H I Arecibo Legacy Fast ALFA (ALFALFA) survey based on their inferred low H I mass and low baryonic mass, and all systems have recent star formation. Thus, the SHIELD sample probes the faint end of the galaxy luminosity function for star-forming galaxies. Here, we measure the distances to the 12 SHIELD galaxies to be between 5 and 12 Mpc bymore » applying the tip of the red giant method to the resolved stellar populations imaged by the Hubble Space Telescope. Based on these distances, the H I masses in the sample range from 4 × 10{sup 6} to 6 × 10{sup 7} M {sub ☉}, with a median H I mass of 1 × 10{sup 7} M {sub ☉}. The tip of the red giant branch distances are up to 73% farther than flow-model estimates in the ALFALFA catalog. Because of the relatively large uncertainties of flow-model distances, we are biased toward selecting galaxies from the ALFALFA catalog where the flow model underestimates the true distances. The measured distances allow for an assessment of the native environments around the sample members. Five of the galaxies are part of the NGC 672 and NGC 784 groups, which together constitute a single structure. One galaxy is part of a larger linear ensemble of nine systems that stretches 1.6 Mpc from end to end. Three galaxies reside in regions with 1-9 neighbors, and four galaxies are truly isolated with no known system identified within a radius of 1 Mpc.« less

Galaxy pairs in the Sloan Digital Sky Survey - VII. The merger-luminous infrared galaxy connection

NASA Astrophysics Data System (ADS)

Ellison, Sara L.; Mendel, J. Trevor; Scudder, Jillian M.; Patton, David R.; Palmer, Michael J. D.

2013-04-01

We use a sample of 9397 low-redshift (z ≤ 0.1) galaxies with a close companion to investigate the connection between mergers and luminous infrared (IR) galaxies (LIRGs). The pairs are selected from the Sloan Digital Sky Survey (SDSS) and have projected separations rp ≤ 80 h{^{- 1}_{70}} kpc, relative velocities ΔV ≤ 300 km s-1 and stellar mass ratios within a factor of 1:10. A control sample consisting of four galaxies per pair galaxy is constructed by simultaneously matching in stellar mass, redshift and environment to galaxies with no close companion. The IR luminosities (LIR) of galaxies in the pair and control samples are determined from the SDSS - Infrared Astronomical Satellite (IRAS) matched catalogue of Hwang et al. Over the redshift range of our pairs sample, the IRAS matches are complete to LIRG luminosities (LIR ≥ 1011 L⊙), allowing us to investigate the connection between mergers and luminous IR galaxies. We find a trend for increasing LIRG fraction towards smaller pair separations, peaking at a factor of ˜5-10 above the median control fraction at the smallest separations (rp < 20 h{^{- 1}_{70}} kpc), but remaining elevated by a factor ˜2-3 even out to 80 h{^{- 1}_{70}} kpc (the widest separations in our sample). LIRG pairs predominantly have high star formation rates (SFRs), high extinction and are found in relatively low-density environments, relative to the full pairs sample. We also find that LIRGs are most likely to be found in high-mass galaxies which have an approximately equal-mass companion. We confirm the results of previous studies that both the active galactic nucleus (AGN) fraction and merger fraction increase strongly as a function of IR luminosity. About 7 per cent of LIRGs are associated with major mergers, as defined within the criteria and mass completion of our sample. Finally, we quantify an SFR offset (ΔSFR) as the enhancement (or decrement) relative to star-forming galaxies of the same mass and redshift. We

Global properties of infrared bright galaxies

NASA Technical Reports Server (NTRS)

Young, Judith S.; Xie, Shuding; Kenney, Jeffrey D. P.; Rice, Walter L.

1989-01-01

Infrared flux densities of 182 galaxies, including 50 galaxies in the Virgo cluster, were analyzed using IRAS data for 12, 25, 60, and 100 microns, and the results were compared with data listed in the Point Source Catalog (PSC, 1985). In addition, IR luminosities, L(IRs), colors, and warm dust masses were derived for these galaxies and were compared with the interstellar gas masses and optical luminosities of the galaxies. It was found that, for galaxies whose optical diameter measures between 5 and 8 arcmin, the PSC flux densities are underestimated by a factor of 2 at 60 microns, and by a factor of 1.5 at 100 microns. It was also found that, for 49 galaxies, the mass of warm dust correlated well with the H2 mass, and that L(IR) correlated with L(H-alpha), demonstrating that the L(IR) measures the rate of star formation in these galaxies.

Morphology Dependence of Stellar Age in Quenched Galaxies at Redshift ˜1.2: Massive Compact Galaxies Are Older than More Extended Ones

NASA Astrophysics Data System (ADS)

Williams, Christina C.; Giavalisco, Mauro; Bezanson, Rachel; Cappelluti, Nico; Cassata, Paolo; Liu, Teng; Lee, Bomee; Tundo, Elena; Vanzella, Eros

2017-04-01

We report the detection of morphology-dependent stellar age in massive quenched galaxies (QGs) at z ˜ 1.2. The sense of the dependence is that compact QGs are 0.5-2 Gyr older than normal-sized ones. The evidence comes from three different age indicators—{D}n4000, {{{H}}}δ , and fits to spectral synthesis models—applied to their stacked optical spectra. All age indicators consistently show that the stellar populations of compact QGs are older than those of their normal-sized counterparts. We detect weak [O II] emission in a fraction of QGs, and the strength of the line, when present, is similar between the two samples; however, compact galaxies exhibit a significantly lower frequency of [O II] emission than normal ones. Fractions of both samples are individually detected in 7 Ms Chandra X-ray images (luminosities ˜1040-1041 erg s-1). The 7 Ms stacks of nondetected galaxies show similarly low luminosities in the soft band only, consistent with a hot gas origin for the X-ray emission. While both [O II] emitters and nonemitters are also X-ray sources among normal galaxies, no compact galaxy with [O II] emission is an X-ray source, arguing against an active galactic nucleus (AGN) powering the line in compact galaxies. We interpret the [O II] properties as further evidence that compact galaxies are older and further along in the process of quenching star formation and suppressing gas accretion. Finally, we argue that the older age of compact QGs is evidence of progenitor bias: compact QGs simply reflect the smaller sizes of galaxies at their earlier quenching epoch, with stellar density most likely having nothing directly to do with cessation of star formation.

SYSTEMATIC VARIATIONS IN CO{sub 2}/H{sub 2}O ICE ABUNDANCE RATIOS IN NEARBY GALAXIES FOUND WITH AKARI NEAR-INFRARED SPECTROSCOPY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamagishi, M.; Kaneda, H.; Ishihara, D.

2015-07-01

We report CO{sub 2}/H{sub 2}O ice abundance ratios in seven nearby star-forming galaxies based on the AKARI near-infrared (2.5–5.0 μm) spectra. The CO{sub 2}/H{sub 2}O ice abundance ratios show clear variations between 0.05 and 0.2 with the averaged value of 0.14 ± 0.01. The previous study on M82 revealed that the CO{sub 2}/H{sub 2}O ice abundance ratios strongly correlate with the intensity ratios of the hydrogen recombination Brα line to the polycyclic aromatic hydrocarbon (PAH) 3.3 μm feature. In the present study, however, we find no correlation for the seven galaxies as a whole due to systematic differences in themore » relation between CO{sub 2}/H{sub 2}O ice abundance and Brα/PAH 3.3 μm intensity ratios from galaxy to galaxy. This result suggests that there is another parameter that determines the CO{sub 2}/H{sub 2}O ice abundance ratios in a galaxy in addition to the Brα/PAH 3.3 μm ratios. We find that the CO{sub 2}/H{sub 2}O ice abundance ratios positively correlate with the specific star formation rates of the galaxies. From these results, we conclude that CO{sub 2}/H{sub 2}O ice abundance ratios tend to be high in young star-forming galaxies.« less

CO excitation in four IR luminous galaxies

NASA Technical Reports Server (NTRS)

Radford, Simon J. E.; Solomon, P. M.; Downes, Dennis

1990-01-01

The correlation between the CO and far infrared luminosities of spiral galaxies is well established. The luminosity ration, L sub FIR/L sub CO in IR luminous active galaxies is, however, systematically five to ten times higher than in ordinary spirals and molecular clouds in our Galaxy. Furthermore, the masses of molecular hydrogen in luminous galaxies are large, M (H2) approx. equals 10(exp 10) solar magnitude, which indicates the observed luminosity ratios are due to an excess of infrared output, rather than a deficiency of molecular gas. These large amounts of molecular gas may fuel luminous galaxies through either star formation or nuclear activity. This interpretation rests on applying the M (H2)/L sub CO ratio calibrated in our Galaxy to galaxies with strikingly different luminosity ratios. But are the physical conditions of the molecular gas different in galaxies with different luminosity ratios. And, if so, does the proportionality between CO and H2 also vary among galaxies. To investigate these questions researchers observed CO (2 to 1) and (1 to 0) emission from four luminous galaxies with the Institute for Radio Astronomy in the Millimeter range (IRAM) 30 m telescope. Researchers conclude that most of the CO emission from these Arp 193, Arp 220, and Mrk 231 arises in regions with moderate ambient densities similar to the clouds in the Milky Way molecular ring. The emission is neither from dense hot cloud cores nor from the cold low density gas characteristic of the envelopes of dark clouds.

The relativistic jet of the γ-ray emitting narrow-line Seyfert 1 galaxy 1H 0323+342

NASA Astrophysics Data System (ADS)

Kynoch, Daniel; Landt, Hermine; Ward, Martin J.; Done, Chris; Gardner, Emma; Boisson, Catherine; Arrieta-Lobo, Maialen; Zech, Andreas; Steenbrugge, Katrien; Pereira Santaella, Miguel

2018-03-01

The detection of several radio-loud narrow-line Seyfert 1 (NLS1) galaxies by the Fermi Gamma-Ray Space Telescope hints at the existence of a rare, new class of γ-ray emitting active galactic nuclei with low black hole masses. Like flat spectrum radio quasars (FSRQs), their γ-ray emission is thought to be produced via the external Compton mechanism whereby relativistic jet electrons upscatter a photon field external to the jet, e.g. from the accretion disc, broad line region (BLR), and dusty torus, to higher energies. Here we study the origin of the γ-ray emission in the lowest-redshift candidate among the currently known γ-ray emitting NLS1s, 1H 0323+342, and take a new approach. We observationally constrain the external photon field using quasi-simultaneous near-infrared, optical, and X-ray spectroscopy. Applying a one-zone leptonic jet model, we simulate the range of jet parameters for which this photon field, when Compton scattered to higher energies, can explain the γ-ray emission. We find that the site of the γ-ray emission lies well within the BLR and that the seed photons mainly originate from the accretion disc. The jet power that we determine, 1.0 × 1045 erg s-1, is approximately half the accretion disc luminosity. We show that this object is not simply a low-mass FSRQ, its jet is intrinsically less powerful than predicted by scaling a typical FSRQ jet by black hole mass and accretion rate. That γ-ray-emitting NLS1s appear to host underpowered jets may go some way to explaining why so few have been detected to date.

H I CONTENT AND OPTICAL PROPERTIES OF FIELD GALAXIES FROM THE ALFALFA SURVEY. II. MULTIVARIATE ANALYSIS OF A GALAXY SAMPLE IN LOW-DENSITY ENVIRONMENTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Toribio, M. Carmen; Solanes, Jose M.; Giovanelli, Riccardo

This is the second paper of two reporting results from a study of the H I content and stellar properties of nearby galaxies detected by the Arecibo Legacy Fast ALFA blind 21 cm line survey and the Sloan Digital Sky Survey in a 2160 deg{sup 2} region of high galactic latitude sky covered by both surveys, in the general Virgo direction. Here, we analyze a complete H I flux-limited subset of 1624 objects with homogeneously measured 21 cm and multi-wavelength optical attributes extracted from the control sample of H I emitters in environments of low local galactic density assembled bymore » Toribio et al. (Paper I). Strategies of multivariate data analysis are applied to this data set in order to (i) investigate the correlation structure of the space defined by an extensive set of potentially independent observables describing gas-rich systems, (ii) identify the intrinsic parameters that best define their neutral gas content, and (iii) explore the scaling relations arising from the joint distributions of the quantities most strongly correlated with the H I mass. The principal component analysis performed over a set of five galaxy properties reveals that they are strongly interrelated, supporting previous claims that nearby H I emitters show a high degree of correlation. The best predictors for the expected value of M{sub HI} are the diameter of the stellar disk, D{sub 25,r}, followed by the total luminosity (both in the r band), and the maximum rotation speed, while morphological proxies such as color show only a moderately strong correlation with the gaseous content attenuated by observational error. Among the various inferred prescriptions, the simplest and most accurate is log(M{sub HI}/M{sub sun}) = 8.72 + 1.25 log(D{sub 25,r}/kpc). We find a slope of -8.2 {+-} 0.5 for the relation between optical magnitude and log rotation speed, in good agreement with Tully-Fisher studies, as well as a log slope of 1.55 {+-} 0.06 for the H I mass-optical galaxy size relation

COSMOS: STOCHASTIC BIAS FROM MEASUREMENTS OF WEAK LENSING AND GALAXY CLUSTERING

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jullo, Eric; Rhodes, Jason; Kiessling, Alina

2012-05-01

In the theory of structure formation, galaxies are biased tracers of the underlying matter density field. The statistical relation between galaxy and matter density field is commonly referred to as galaxy bias. In this paper, we test the linear bias model with weak-lensing and galaxy clustering measurements in the 2 deg{sup 2} COSMOS field. We estimate the bias of galaxies between redshifts z = 0.2 and z = 1 and over correlation scales between R = 0.2 h{sup -1} Mpc and R = 15 h{sup -1} Mpc. We focus on three galaxy samples, selected in flux (simultaneous cuts I{sub 814W}more » < 26.5 and K{sub s} < 24) and in stellar mass (10{sup 9} < M{sub *} < 10{sup 10} h{sup -2} M{sub Sun} and 10{sup 10} < M{sub *} < 10{sup 11} h{sup -2} M{sub Sun }). At scales R > 2 h{sup -1} Mpc, our measurements support a model of bias increasing with redshift. The Tinker et al. fitting function provides a good fit to the data. We find the best-fit mass of the galaxy halos to be log (M{sub 200}/h{sup -1} M{sub Sun }) = 11.7{sup +0.6}{sub -1.3} and log (M{sub 200}/h{sup -1} M{sub Sun }) = 12.4{sup +0.2}{sub -2.9}, respectively, for the low and high stellar-mass samples. In the halo model framework, bias is scale dependent with a change of slope at the transition scale between the one and the two halo terms. We detect a scale dependence of bias with a turndown at scale R = 2.3 {+-} 1.5 h{sup -1} Mpc, in agreement with previous galaxy clustering studies. We find no significant amount of stochasticity, suggesting that a linear bias model is sufficient to describe our data. We use N-body simulations to quantify both the amount of cosmic variance and systematic errors in the measurement.« less

ESTIMATING THE STAR FORMATION RATE AT 1 kpc SCALES IN NEARBY GALAXIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leroy, Adam K.; Munoz-Mateos, Juan-Carlos; Bigiel, Frank

2012-07-15

Using combinations of H{alpha}, ultraviolet (UV), and infrared (IR) emission, we estimate the star formation rate (SFR) surface density, {Sigma}{sub SFR}, at 1 kpc resolution for 30 disk galaxies that are targets of the IRAM HERACLES CO survey. We present a new physically motivated IR spectral-energy-distribution-based approach to account for possible contributions to 24 {mu}m emission not associated with recent star formation. Considering a variety of 'reference' SFRs from the literature, we revisit the calibration of the 24 {mu}m term in hybrid (UV+IR or H{alpha}+IR) tracers. We show that the overall calibration of this term remains uncertain at the factormore » of two level because of the lack of wide-field, robust reference SFR estimates. Within this uncertainty, published calibrations represent a reasonable starting point for 1 kpc-wide areas of star-forming disk galaxies, but we re-derive and refine the calibration of the IR term in these tracers to match our resolution and approach to 24 {mu}m emission. We compare a large suite of {Sigma}{sub SFR} estimates and find that above {Sigma}{sub SFR} {approx} 10{sup -3} M{sub Sun} yr{sup -1} kpc{sup -2} the systematic differences among tracers are less than a factor of two across two orders of magnitude dynamic range. We caution that methodology and data both become serious issues below this level. We note from simple model considerations that when focusing on a part of a galaxy dominated by a single stellar population, the intrinsic uncertainty in H{alpha}- and FUV-based SFRs is {approx}0.3 and {approx}0.5 dex.« less

Large scale structures around radio galaxies at z ~ 1.5

NASA Astrophysics Data System (ADS)

Galametz, A.; De Breuck, C.; Vernet, J.; Stern, D.; Rettura, A.; Marmo, C.; Omont, A.; Allen, M.; Seymour, N.

2009-11-01

We explore the environments of two radio galaxies at z ~ 1.5, 7C 1751+6809 and 7C 1756+6520, using deep optical and near-infrared imaging. Our data cover 15×15 arcmin2 fields around the radio galaxies. We develop and apply BzK color criteria to select cluster member candidates around the radio galaxies and find no evidence of an overdensity of red galaxies within 2 Mpc of 7C 1751+6809. In contrast, 7C 1756+6520 shows a significant overdensity of red galaxies within 2 Mpc of the radio galaxy, by a factor of 3.1±0.8 relative to the four MUSYC fields. At small separation (r < 6 arcsec), this radio galaxy also has one z > 1.4 evolved galaxy candidate, one z > 1.4 star-forming galaxy candidate, and an AGN candidate (at indeterminate redshift). This is suggestive of several close-by companions. Several concentrations of red galaxies are also noticed in the full 7C 1756+6520 field, forming a possible large-scale structure of evolved galaxies with a NW-SE orientation. We construct the color-magnitude diagram of red galaxies found near 7C 1756+6520 (r < 2 Mpc), and find a clear red sequence that is truncated at Ks ~ 21.5 (AB). We also find an overdensity of mid-infrared selected AGN in the surroundings of 7C 1756+6520. These results are suggestive of a proto-cluster at high redshift. Tables 2-6 are only available in electronic form at http://www.aanda.org

Properties of the giant H II regions and bar in the nearby spiral galaxy NGC 5430

NASA Astrophysics Data System (ADS)

Brière, É.; Cantin, S.; Spekkens, K.

2012-09-01

In order to better understand the impact of the bar on the evolution of spiral galaxies, we measure the properties of giant H II regions and the bar in the SB(s)b galaxy NGC 5430. We use two complementary data sets, both obtained at the Observatoire du Mont-Mégantic: a hyperspectral data cube from the imaging Fourier transform spectrograph SpIOMM (Spectromètre-Imageur à transformée de Fourier de l-Observatoire du Mont-Mégantic) and high-resolution spectra across the bar from a long-slit spectrograph. We flux-calibrate SpIOMM spectra for the first time, and produce Hα and [N II]λ6584 Å intensity maps from which we identify 51 giant H II regions in the spiral arms and bar. We evaluate the type of activity, the oxygen abundance and the age of the young populations contained in these giant H II regions and in the bar. Thus, we confirm that NGC 5430 does not harbour a strong active galactic nucleus, and that its Wolf-Rayet knot shows a pure H II region nature. We find no variation in abundance or age between the bar and spiral arms, nor as a function of galactocentric radius. These results are consistent with the hypothesis that a chemical mixing mechanism is at work in the galaxy's disc to flatten the oxygen abundance gradient. Using the STARBURST99 model, we estimate the ages of the young populations, and again find no variations in age between the bar and the arms or as a function of radius. Instead, we find evidence for two galaxy-wide waves of star formation, about 7.1 and 10.5 Myr ago. While the bar in NGC 5430 is an obvious candidate to trigger these two episodes, it is not clear how the bar could induce widespread star formation on such a short time-scale.

Galaxy Downsizing Evidenced by Hybrid Evolutionary Tracks

NASA Astrophysics Data System (ADS)

Firmani, C.; Avila-Reese, V.

2010-11-01

The stellar-dark halo mass relation of galaxies at different redshifts, M s(M h, z), encloses relevant features concerning their physical processes and evolution. This sequence of relations, defined in the range 0 < z < 4, together with average Λ cold dark matter (ΛCDM) halo mass aggregation histories (MAHs), is used here for inferring average galaxian hybrid evolutionary tracks (GHETs), where "hybrid" remarks on the combination of observational (M s) and theoretical (M h) ingredients. As a result of our approach, a unified picture of stellar and halo mass buildup, population migration, and downsizing of galaxies as a function of mass is presented. The inferred average M s growth histories (GHETs) of the highest and lowest mass galaxies are definitively quite different from the average MAHs, M h(z), of the corresponding dark halos. Depending on how a given M h(z) compares with the mass at which the M s-to-M h ratio curve peaks at the epoch z, M hp(z), two evolutionary phases are evidenced: (1) galaxies in an active regime of M s growth when M h < M hp and (2) galaxies in a quiescent or passive regime when M h>M hp. The typical M s at which galaxies transit from the active (star-forming) to the quiescent regime, M tran, increases with z, log(M tran/M sun) ≈10.30 + 0.55z, making evident a population downsizing phenomenon. This result agrees with independent observational determinations based on the evolution of the galaxy stellar mass function decomposition into blue and red galaxy populations. The specific star formation rate (SSFR) predicted from the derivative of the GHET is consistent with direct measures of the SSFR for galaxies at different redshifts, though both sets of observational inferences are independent. The average GHETs of galaxies smaller than M tran at z = 0 (M s ≈1010.3 M sun, M h ≈1011.8 M sun) did not reach the quiescent regime, and for them, the lower the mass, the faster the later M s growth rate (downsizing in SSFR). The GHETs allow us

The Rings Survey. I. Hα and H I Velocity Maps of Galaxy NGC 2280

NASA Astrophysics Data System (ADS)

Mitchell, Carl J.; Williams, T. B.; Spekkens, Kristine; Lee-Waddell, K.; Kuzio de Naray, Rachel; Sellwood, J. A.

2015-03-01

Precise measurements of gas kinematics in the disk of a spiral galaxy can be used to estimate its mass distribution. The Southern African Large Telescope has a large collecting area and field of view, and is equipped with a Fabry-Pérot (FP) interferometer that can measure gas kinematics in a galaxy from the Hα line. To take advantage of this capability, we have constructed a sample of 19 nearby spiral galaxies, the RSS Imaging and Spectroscopy Nearby Galaxy Survey, as targets for detailed study of their mass distributions and have collected much of the needed data. In this paper, we present velocity maps produced from Hα FP interferometry and H i aperture synthesis for one of these galaxies, NGC 2280, and show that the two velocity measurements are generally in excellent agreement. Minor differences can mostly be attributed to the different spatial distributions of the excited and neutral gas in this galaxy, but we do detect some anomalous velocities in our Hα velocity map of the kind that have previously been detected in other galaxies. Models produced from our two velocity maps agree well with each other and our estimates of the systemic velocity and projection angles confirm previous measurements of these quantities for NGC 2280. Based in part on observations obtained with the Southern African Large Telescope (SALT) program 2011-3-RU-003.

Galaxy populations in massive galaxy clusters to $z$ = 1.1: Color distribution, concentration, halo occupation number and red sequence fraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hennig, C.; Mohr, Joseph J.; Zenteno, A.

We study the galaxy populations in 74 Sunyaev–Zeldovich effect selected clusters from the South Pole Telescope survey, which have been imaged in the science verification phase of the Dark Energy Survey. The sample extends up to z ~ 1.1 with 4 × 10 14 M⊙ ≤ M200 ≤ 3 × 10 15M⊙. Using the band containing the 4000 Å break and its redward neighbour, we study the colour–magnitude distributions of cluster galaxies to ~m* + 2, finding that: (1)The intrinsic rest frame g – r colour width of the red sequence (RS) population is ~0.03 out to z ~ 0.85 with a preference for an increase to ~0.07 at z = 1, and (2) the prominence of the RS declines beyond z ~ 0.6. The spatial distribution of cluster galaxies is well described by the NFW profile out to 4R200 with a concentration of c g = 3.59more » $$+0.20\\atop{–0.18}$$, 5.37$$+0.27\\atop{-0.24}$$ and 1.38$$+0.21\\atop{-0.19}$$ for the full, the RS and the blue non-RS populations, respectively, but with ~40 per cent to 55 per cent cluster to cluster variation and no statistically significant redshift or mass trends. The number of galaxies within the virial region N200 exhibits a mass trend indicating that the number of galaxies per unit total mass is lower in the most massive clusters, and shows no significant redshift trend. The RS fraction within R200 is (68 ± 3) per cent at z = 0.46, varies from ~55 per cent at z = 1 to ~80 per cent at z = 0.1 and exhibits intrinsic variation among clusters of ~14 per cent. Finally, we discuss a model that suggests that the observed redshift trend in RS fraction favours a transformation time-scale for infalling field galaxies to become RS galaxies of 2–3 Gyr.« less

Galaxy populations in massive galaxy clusters to $z$ = 1.1: Color distribution, concentration, halo occupation number and red sequence fraction

DOE PAGES

Hennig, C.; Mohr, Joseph J.; Zenteno, A.; ...

2017-01-23

We study the galaxy populations in 74 Sunyaev–Zeldovich effect selected clusters from the South Pole Telescope survey, which have been imaged in the science verification phase of the Dark Energy Survey. The sample extends up to z ~ 1.1 with 4 × 10 14 M⊙ ≤ M200 ≤ 3 × 10 15M⊙. Using the band containing the 4000 Å break and its redward neighbour, we study the colour–magnitude distributions of cluster galaxies to ~m* + 2, finding that: (1)The intrinsic rest frame g – r colour width of the red sequence (RS) population is ~0.03 out to z ~ 0.85 with a preference for an increase to ~0.07 at z = 1, and (2) the prominence of the RS declines beyond z ~ 0.6. The spatial distribution of cluster galaxies is well described by the NFW profile out to 4R200 with a concentration of c g = 3.59more » $$+0.20\\atop{–0.18}$$, 5.37$$+0.27\\atop{-0.24}$$ and 1.38$$+0.21\\atop{-0.19}$$ for the full, the RS and the blue non-RS populations, respectively, but with ~40 per cent to 55 per cent cluster to cluster variation and no statistically significant redshift or mass trends. The number of galaxies within the virial region N200 exhibits a mass trend indicating that the number of galaxies per unit total mass is lower in the most massive clusters, and shows no significant redshift trend. The RS fraction within R200 is (68 ± 3) per cent at z = 0.46, varies from ~55 per cent at z = 1 to ~80 per cent at z = 0.1 and exhibits intrinsic variation among clusters of ~14 per cent. Finally, we discuss a model that suggests that the observed redshift trend in RS fraction favours a transformation time-scale for infalling field galaxies to become RS galaxies of 2–3 Gyr.« less

The bulge-disc decomposed evolution of massive galaxies at 1 < z < 3 in CANDELS

NASA Astrophysics Data System (ADS)

Bruce, V. A.; Dunlop, J. S.; McLure, R. J.; Cirasuolo, M.; Buitrago, F.; Bowler, R. A. A.; Targett, T. A.; Bell, E. F.; McIntosh, D. H.; Dekel, A.; Faber, S. M.; Ferguson, H. C.; Grogin, N. A.; Hartley, W.; Kocevski, D. D.; Koekemoer, A. M.; Koo, D. C.; McGrath, E. J.

2014-10-01

We present the results of a new and improved study of the morphological and spectral evolution of massive galaxies over the redshift range 1 < z < 3. Our analysis is based on a bulge-disc decomposition of 396 galaxies with M* > 1011 M⊙ uncovered from the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) Wide Field Camera 3 (WFC3)/IR imaging within the Cosmological Evolution Survey (COSMOS) and UKIRT Infrared Deep Sky Survey (UKIDSS) UDS survey fields. We find that, by modelling the H160 image of each galaxy with a combination of a de Vaucouleurs bulge (Sérsic index n = 4) and an exponential disc (n = 1), we can then lock all derived morphological parameters for the bulge and disc components, and successfully reproduce the shorter-wavelength J125, i814, v606 HST images simply by floating the magnitudes of the two components. This then yields sub-divided four-band HST photometry for the bulge and disc components which, with no additional priors, is well described by spectrophotometric models of galaxy evolution. Armed with this information, we are able to properly determine the masses and star formation rates for the bulge and disc components, and find that: (i) from z = 3 to 1 the galaxies move from disc dominated to increasingly bulge dominated, but very few galaxies are pure bulges/ellipticals by z = 1; (ii) while most passive galaxies are bulge dominated, and most star-forming galaxies disc dominated, 18 ± 5 per cent of passive galaxies are disc dominated, and 11 ± 3 per cent of star-forming galaxies are bulge dominated, a result which needs to be explained by any model purporting to connect star formation quenching with morphological transformations; (iii) there exists a small but significant population of pure passive discs, which are generally flatter than their star-forming counterparts (whose axial ratio distribution peaks at b/a ≃ 0.7); (iv) flatter/larger discs re-emerge at the highest star formation rates, consistent with

Halo Histories vs. Galaxy Properties at z=0, III: The Properties of Star-Forming Galaxies

NASA Astrophysics Data System (ADS)

Tinker, Jeremy L.; Hahn, ChangHoon; Mao, Yao-Yuan; Wetzel, Andrew R.

2018-05-01

We measure how the properties of star-forming central galaxies correlate with large-scale environment, δ, measured on 10 h-1Mpc scales. We use galaxy group catalogs to isolate a robust sample of central galaxies with high purity and completeness. The galaxy properties we investigate are star formation rate (SFR), exponential disk scale length Rexp, and Sersic index of the galaxy light profile, nS. We find that, at all stellar masses, there is an inverse correlation between SFR and δ, meaning that above-average star forming centrals live in underdense regions. For nS and Rexp, there is no correlation with δ at M_\\ast ≲ 10^{10.5} M⊙, but at higher masses there are positive correlations; a weak correlation with Rexp and a strong correlation with nS. These data are evidence of assembly bias within the star-forming population. The results for SFR are consistent with a model in which SFR correlates with present-day halo accretion rate, \\dot{M}_h. In this model, galaxies are assigned to halos using the abundance matching ansatz, which maps galaxy stellar mass onto halo mass. At fixed halo mass, SFR is then assigned to galaxies using the same approach, but \\dot{M}_h is used to map onto SFR. The best-fit model requires some scatter in the \\dot{M}_h-SFR relation. The Rexp and nS measurements are consistent with a model in which both of these quantities are correlated with the spin parameter of the halo, λ. Halo spin does not correlate with δ at low halo masses, but for higher mass halos, high-spin halos live in higher density environments at fixed Mh. Put together with the earlier installments of this series, these data demonstrate that quenching processes have limited correlation with halo formation history, but the growth of active galaxies, as well as other detailed galaxies properties, are influenced by the details of halo assembly.

Detection of CO emission in Hydra 1 cluster galaxies

NASA Technical Reports Server (NTRS)

Huchtmeier, W. K.

1990-01-01

A survey of bright Hydra cluster spiral galaxies for the CO(1-0) transition at 115 GHz was performed with the 15m Swedish-ESO submillimeter telescope (SEST). Five out of 15 galaxies observed have been detected in the CO(1-0) line. The largest spiral galaxy in the cluster, NGC 3312, got more CO than any spiral of the Virgo cluster. This Sa-type galaxy is optically largely distorted and disrupted on one side. It is a good candidate for ram pressure stripping while passing through the cluster's central region. A comparison with global CO properties of Virgo cluster spirals shows a relatively good agreement with the detected Hydra cluster galaxies.

Spatially Resolved HST Grism Spectroscopy of a Lensed Emission Line Galaxy at z ~ 1

NASA Astrophysics Data System (ADS)

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

2012-07-01

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 775 = 27.3 via slitless grism spectroscopy. One ELG (at z = 0.7895) is very bright owing to lensing magnification by a factor of ≈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 * ≈ 2 × 109 M ⊙) with a high specific star formation rate (≈20 Gyr-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 ~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 ~1 kpc have a placement on the blue H II region excitation diagram with f ([O III])/f (Hβ) and f ([Ne III])/f (Hβ) 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. Based, in part, on data obtained with the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA, and was made possible by the generous financial support of the W. M. Keck Foundation.

The CO-12 and CO-13 J=2-1 and J=1-0 observations of hot and cold galaxies

NASA Technical Reports Server (NTRS)

Xie, Shuding; Schloerb, F. Peter; Young, Judith

1990-01-01

Researchers observed the nuclear regions of the galaxies NGC 2146 and IC 342 in CO-12 and CO-13 J=1-0 and J=2-1 lines using the Five College Radio Astronomy Observatory (FCRAO) 14m telescope. NGC 2146 is a peculiar Sab spiral galaxy. Its complex optical morphology and strong nuclear radio continuum emission suggest that it is experiencing a phase of violent activity and could have a polar ring which may have resulted from an interaction. IC 342 is a nearby luminous Scd spiral galaxy. Strong CO, infrared and radio continuum emission from the nuclear region of IC 342 indicate enhanced star-forming activity, and interferometric CO-12 J=1-0 observations reveal a bar-like structure centered on the nucleus, along the dark lane in the NS direction. These two galaxies are selected based on their different dust temperatures and star formation efficiencies (SFE) as derived from the Infrared Astronomy Satellite (IRAS) S sub 60 mu/S sub 100 mu flux density ratio and L sub IR/M(H2), respectively, with a relatively high SFE and dust temperature of 45 K in NGC 2146 and a relatively low SFE and dust temperature of 35 K in IC 342. The data from the different CO-12 and CO-13 lines are used to study the physical conditions in the molecular clouds in the galaxies. Researchers also consider the radiative transfer to determine whether a warm and optically thin gas component exists in these galaxies, as has been suggested in the case of M82 (Knapp et al. 1980), and whether the warm gas is related to the dust properties. Since optically thin CO-12 gas is rarely detected in our own Galaxy (except in outflow sources), to confirm its existence in external galaxies is very important in understanding the molecular content of external galaxies and its relationship to star formation activity. The present CO-12 J=2-1 and CO-13 J=2-1 and J=1-0 data for NGC 2146 are the first detections of this galaxy to our knowledge. The CO-12 J=1-0 distribution in NGC 2146 has been measured as part of the FCRAO

The RSA survey of dwarf galaxies, 1: Optical photometry

NASA Technical Reports Server (NTRS)

Vader, J. Patricia; Chaboyer, Brian

1994-01-01

We present detailed surface photometry, based on broad B-band charge coupled device (CCD) images, of about 80 dwarf galaxies. Our sample represents approximately 10% of all dwarf galaxies identified in the vicinity of Revised Shapley-Ames (RSA) galaxies on high resolution blue photographic plates, referred to as the RSA survey of dwarf galaxies. We derive global properties and radial surface brightness profiles, and examine the morphologies. The radial surface brightness profiles of dwarf galaxies, whether early or late type, display the same varieties in shape and complexity as those of classical giant galaxies. Only a few are well described by a pure r(exp 1/4) law. Exponential profiles prevail. Features typical of giant disk galaxies, such as exponential profiles with a central depression, lenses, and even, in one case (IC 2041), a relatively prominent bulge are also found in dwarf galaxies. Our data suggest that the central region evolves from being bulge-like, with an r(exp 1/4) law profile, in bright galaxies to a lens-like structure in dwarf galaxies. We prove detailed surface photometry to be a helpful if not always sufficient tool in investigating the structure of dwarf galaxies. In many cases kinematic information is needed to complete the picture. We find the shapes of the surface brightness profiles to be loosely associated with morphological type. Our sample contains several new galaxies with properties intermediate between those of giant and dwarf ellipticals (but no M32-like objects). This shows that such intermediate galaxies exist so that at least a fraction of early-type dwarf ellipticals is structurally related to early-type giants instead of belonging to a totally unrelated, disjunct family. This supports an origin of early-type dwarf galaxies as originally more massive systems that acquired their current morphology as a result of substantial, presumable supernova-driven, mass loss. On the other hand, several early-type dwarfs in our sample are

Discovering Massive z > 1 Galaxy Clusters with Spitzer and SPTpol

NASA Astrophysics Data System (ADS)

Bleem, Lindsey; Brodwin, Mark; Ashby, Matthew; Stalder, Brian; Klein, Matthias; Gladders, Michael; Stanford, Spencer; Canning, Rebecca

2018-05-01

We propose to obtain Spitzer/IRAC imaging of 50 high-redshift galaxy cluster candidates derived from two new completed SZ cluster surveys by the South Pole Telescope. Clusters from the deep SPTpol 500-square-deg main survey will extend high-redshift SZ cluster science to lower masses (median M500 2x10^14Msun) while systems drawn from the wider 2500-sq-deg SPTpol Extended Cluster Survey are some of the rarest most massive high-z clusters in the observable universe. The proposed small 10 h program will enable (1) confirmation of these candidates as high-redshift clusters, (2) measurements of the cluster redshifts (sigma_z/(1+z) 0.03), and (3) estimates of the stellar masses of the brightest cluster members. These observations will yield exciting and timely targets for the James Webb Space Telescope--and, combined with lower-z systems--will both extend cluster tests of dark energy to z>1 as well as enable studies of galaxy evolution in the richest environments for a mass-limited cluster sample from 01.8.

Galaxy-galaxy lensing in EAGLE: comparison with data from 180 deg2 of the KiDS and GAMA surveys

NASA Astrophysics Data System (ADS)

Velliscig, Marco; Cacciato, Marcello; Hoekstra, Henk; Schaye, Joop; Heymans, Catherine; Hildebrandt, Hendrik; Loveday, Jon; Norberg, Peder; Sifón, Cristóbal; Schneider, Peter; van Uitert, Edo; Viola, Massimo; Brough, Sarah; Erben, Thomas; Holwerda, Benne W.; Hopkins, Andrew M.; Kuijken, Konrad

2017-11-01

We present predictions for the galaxy-galaxy lensing (GGL) profile from the EAGLE hydrodynamical cosmological simulation at redshift z = 0.18, in the spatial range 0.02 < R/(h- 1 Mpc) < 2, and for five logarithmically equispaced stellar mass bins in the range 10.3 < log10(Mstar/ M⊙) < 11.8. We compare these excess surface density profiles to the observed signal from background galaxies imaged by the Kilo Degree Survey around spectroscopically confirmed foreground galaxies from the Galaxy And Mass Assembly (GAMA) survey. Exploiting the GAMA galaxy group catalogue, the profiles of central and satellite galaxies are computed separately for groups with at least five members to minimize contamination. EAGLE predictions are in broad agreement with the observed profiles for both central and satellite galaxies, although the signal is underestimated at R ≈ 0.5-2 h- 1 Mpc for the highest stellar mass bins. When central and satellite galaxies are considered simultaneously, agreement is found only when the selection function of lens galaxies is taken into account in detail. Specifically, in the case of GAMA galaxies, it is crucial to account for the variation of the fraction of satellite galaxies in bins of stellar mass induced by the flux-limited nature of the survey. We report the inferred stellar-to-halo mass relation and we find good agreement with recent published results. We note how the precision of the GGL profiles in the simulation holds the potential to constrain fine-grained aspects of the galaxy-dark matter connection.

The evolutionary sequence of post-starburst galaxies

NASA Astrophysics Data System (ADS)

Wilkinson, C. L.; Pimbblet, K. A.; Stott, J. P.

2017-12-01

There are multiple ways in which to select post-starburst galaxies in the literature. In this work, we present a study into how two well-used selection techniques have consequences on observable post-starburst galaxy parameters, such as colour, morphology and environment, and how this affects interpretations of their role in the galaxy duty cycle. We identify a master sample of H δ strong (EWH δ > 3Å) post-starburst galaxies from the value-added catalogue in the seventh data release of the Sloan Digital Sky Survey (SDSS DR7) over a redshift range 0.01 < z < 0.1. From this sample we select two E+A subsets, both having a very little [O II] emission (EW_[O II] > -2.5 Å) but one having an additional cut on EWHα (>-3 Å). We examine the differences in observables and AGN fractions to see what effect the H α cut has on the properties of post-starburst galaxies and what these differing samples can tell us about the duty cycle of post-starburst galaxies. We find that H δ strong galaxies peak in the 'blue cloud', E+As in the 'green valley' and pure E+As in the 'red sequence'. We also find that pure E+As have a more early-type morphology and a higher fraction in denser environments compared with the H δ strong and E+A galaxies. These results suggest that there is an evolutionary sequence in the post-starburst phase from blue discy galaxies with residual star formation to passive red early-types.

DUST EXTINCTION FROM BALMER DECREMENTS OF STAR-FORMING GALAXIES AT 0.75 {<=} z {<=} 1.5 WITH HUBBLE SPACE TELESCOPE/WIDE-FIELD-CAMERA 3 SPECTROSCOPY FROM THE WFC3 INFRARED SPECTROSCOPIC PARALLEL SURVEY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dominguez, A.; Siana, B.; Masters, D.

Spectroscopic observations of H{alpha} and H{beta} emission lines of 128 star-forming galaxies in the redshift range 0.75 {<=} z {<=} 1.5 are presented. These data were taken with slitless spectroscopy using the G102 and G141 grisms of the Wide-Field-Camera 3 (WFC3) on board the Hubble Space Telescope as part of the WFC3 Infrared Spectroscopic Parallel survey. Interstellar dust extinction is measured from stacked spectra that cover the Balmer decrement (H{alpha}/H{beta}). We present dust extinction as a function of H{alpha} luminosity (down to 3 Multiplication-Sign 10{sup 41} erg s{sup -1}), galaxy stellar mass (reaching 4 Multiplication-Sign 10{sup 8} M {sub Sunmore » }), and rest-frame H{alpha} equivalent width. The faintest galaxies are two times fainter in H{alpha} luminosity than galaxies previously studied at z {approx} 1.5. An evolution is observed where galaxies of the same H{alpha} luminosity have lower extinction at higher redshifts, whereas no evolution is found within our error bars with stellar mass. The lower H{alpha} luminosity galaxies in our sample are found to be consistent with no dust extinction. We find an anti-correlation of the [O III] {lambda}5007/H{alpha} flux ratio as a function of luminosity where galaxies with L {sub H{alpha}} < 5 Multiplication-Sign 10{sup 41} erg s{sup -1} are brighter in [O III] {lambda}5007 than H{alpha}. This trend is evident even after extinction correction, suggesting that the increased [O III] {lambda}5007/H{alpha} ratio in low-luminosity galaxies is likely due to lower metallicity and/or higher ionization parameters.« less

Cold atomic hydrogen in the inner galaxy

NASA Technical Reports Server (NTRS)

Dickey, J. M.; Garwood, R. W.

1986-01-01

The VLA is used to measure 21 cm absorption in directions with the absolute value of b less than 1 deg., the absolute value of 1 less than 25 deg. to probe the cool atomic gas in the inner galaxy. Abundant H I absorption is detected; typical lines are deep and narrow, sometimes blending in velocity with adjacent features. Unlike 21 cm emission not all allowed velocities are covered: large portions of the l-v diagram are optically thin. Although not similar to H I emission, the absorption shows a striking correspondence with CO emission in the inner galaxy: essentially every strong feature detected in one survey is seen in the other. The provisional conclusion is that in the inner galaxy most cool atomic gas is associated with molecular cloud complexes. There are few or no cold atomic clouds devoid of molecules in the inner galaxy, although these are common in the outer galaxy.

Redshifts for 2410 Galaxies in the Century Survey Region

NASA Astrophysics Data System (ADS)

Wegner, Gary; Thorstensen, John R.; Kurtz, Michael J.; Brown, Warren R.; Fabricant, Daniel G.; Geller, Margaret J.; Huchra, John P.; Marzke, Ronald O.; Sakai, Shoko

2001-12-01

The Century Survey strip covers 102 deg2 within the limits 8h5<=α<=16h5, 29.0d<=δ<=30.0d, equinox B1950.0. The strip passes through the Corona Borealis supercluster and the outer region of the Coma cluster. Within the Century Survey region, we have measured 2410 redshifts that constitute four overlapping complete redshift surveys: (1) 1728 galaxies with Kron-Cousins Rph<=16.13 covering the entire strip, (2) 507 galaxies with Rph<=16.4 in right ascension range 8h32m<=α<=10 h45m, equinox B1950.0, (3) 1251 galaxies with absorption- and K-corrected RCCDc<=16.2 (where ``c'' indicates ``corrected'') covering the right ascension range 8h5<=α<=13h5, equinox B1950.0, and (4) 1255 galaxies with absorption- and K-corrected VCCDc<=16.7 also covering the right ascension range 8h5<=α<=13h5, equinox B1950.0. All these redshift samples are more than 98% complete to the specified magnitude limit. We derived samples 1 and 2 from scans of the POSS1 red (E) plates calibrated with CCD photometry. We derived samples 3 and 4 from deep V and R CCD images covering the entire region. We include coarse morphological types for all the galaxies in sample 1. The distribution of (V-R)CCD for each type corresponds appropriately with the classification. Work reported here is based partly on observations obtained at the Michigan-Dartmouth-MIT Observatory.

Spectroscopic Confirmation of Five Galaxy Clusters at z > 1.25 in the 2500 deg^2 SPT-SZ Survey

NASA Astrophysics Data System (ADS)

Khullar, Gourav; Bleem, Lindsey; Bayliss, Matthew; Gladders, Michael; South Pole Telescope (SPT) Collaboration

2018-06-01

We present spectroscopic confirmation of 5 galaxy clusters at 1.25 < z < 1.5, discovered in the 2500 deg2 South Pole Telescope Sunyaev-Zel’dovich (SPT-SZ) survey. These clusters, taken from a nearly redshift-independent mass-limited sample of clusters, have multi-wavelength follow-up imaging data from the X-ray to the near-IR, and currently form the most homogenous massive high-redshift cluster sample in existence. We briefly describe the analysis pipeline used on the low S/N spectra of these faint galaxies, and describing the multiple techniques used to extract robust redshifts from a combination of absorption-line (Ca II H&K doublet - λλ3934,3968Å) and emission-line ([OII] λλ3727,3729Å) spectral features. We present several ensemble analyses of cluster member galaxies that demonstrate the reliability of the measured redshifts. We also identify modest [OII] emission and pronounced CN and Hδ absorption in a composite stacked spectrum of 28 low S/N passive galaxy spectra with redshifts derived primarily from Ca II H&K features. This work increases the number of spectroscopically-confirmed SPT-SZ galaxy clusters at z > 1.25 from 2 to 7, further demonstrating the efficacy of SZ selection for the highest redshift massive clusters, and enabling further detailed study of these confirmed systems.

Galaxy Clustering in Early Sloan Digital Sky Survey Redshift Data

NASA Astrophysics Data System (ADS)

Zehavi, Idit; Blanton, Michael R.; Frieman, Joshua A.; Weinberg, David H.; Mo, Houjun J.; Strauss, Michael A.; Anderson, Scott F.; Annis, James; Bahcall, Neta A.; Bernardi, Mariangela; Briggs, John W.; Brinkmann, Jon; Burles, Scott; Carey, Larry; Castander, Francisco J.; Connolly, Andrew J.; Csabai, Istvan; Dalcanton, Julianne J.; Dodelson, Scott; Doi, Mamoru; Eisenstein, Daniel; Evans, Michael L.; Finkbeiner, Douglas P.; Friedman, Scott; Fukugita, Masataka; Gunn, James E.; Hennessy, Greg S.; Hindsley, Robert B.; Ivezić, Željko; Kent, Stephen; Knapp, Gillian R.; Kron, Richard; Kunszt, Peter; Lamb, Donald Q.; Leger, R. French; Long, Daniel C.; Loveday, Jon; Lupton, Robert H.; McKay, Timothy; Meiksin, Avery; Merrelli, Aronne; Munn, Jeffrey A.; Narayanan, Vijay; Newcomb, Matt; Nichol, Robert C.; Owen, Russell; Peoples, John; Pope, Adrian; Rockosi, Constance M.; Schlegel, David; Schneider, Donald P.; Scoccimarro, Roman; Sheth, Ravi K.; Siegmund, Walter; Smee, Stephen; Snir, Yehuda; Stebbins, Albert; Stoughton, Christopher; SubbaRao, Mark; Szalay, Alexander S.; Szapudi, Istvan; Tegmark, Max; Tucker, Douglas L.; Uomoto, Alan; Vanden Berk, Dan; Vogeley, Michael S.; Waddell, Patrick; Yanny, Brian; York, Donald G.

2002-05-01

We present the first measurements of clustering in the Sloan Digital Sky Survey (SDSS) galaxy redshift survey. Our sample consists of 29,300 galaxies with redshifts 5700kms-1<=cz<=39,000kms-1, distributed in several long but narrow (2.5d-5°) segments, covering 690 deg2. For the full, flux-limited sample, the redshift-space correlation length is approximately 8 h-1 Mpc. The two-dimensional correlation function ξ(rp,π) shows clear signatures of both the small-scale, ``fingers-of-God'' distortion caused by velocity dispersions in collapsed objects and the large-scale compression caused by coherent flows, though the latter cannot be measured with high precision in the present sample. The inferred real-space correlation function is well described by a power law, ξ(r)=(r/6.1+/-0.2h-1Mpc)-1.75+/-0.03, for 0.1h-1Mpc<=r<=16h-1Mpc. The galaxy pairwise velocity dispersion is σ12~600+/-100kms-1 for projected separations 0.15h-1Mpc<=rp<=5h-1Mpc. When we divide the sample by color, the red galaxies exhibit a stronger and steeper real-space correlation function and a higher pairwise velocity dispersion than do the blue galaxies. The relative behavior of subsamples defined by high/low profile concentration or high/low surface brightness is qualitatively similar to that of the red/blue subsamples. Our most striking result is a clear measurement of scale-independent luminosity bias at r<~10h-1Mpc: subsamples with absolute magnitude ranges centered on M*-1.5, M*, and M*+1.5 have real-space correlation functions that are parallel power laws of slope ~-1.8 with correlation lengths of approximately 7.4, 6.3, and 4.7 h-1 Mpc, respectively.

Swift follow-up of the flaring NLSy1 1H 0323+342

NASA Astrophysics Data System (ADS)

D'Ammando, Filippo; Carpenter, Bryce; Ojha, Roopesh

2013-09-01

Following the gamma-ray flaring activity of the narrow-line Seyfert 1 galaxy 1H 0323+342 (also known as 2FGL J0324.8+3408; Nolan et al. 2012, ApJS, 199, 31) detected by Fermi LAT on 2013 August 28 (ATel #5344), a Swift target of opportunity observation was performed on August 30.

Magnetic fields in spiral galaxies

NASA Astrophysics Data System (ADS)

Krause, Marita

2015-03-01

The magnetic field structure in edge-on galaxies observed so far shows a plane-parallel magnetic field component in the disk of the galaxy and an X-shaped field in its halo. The plane-parallel field is thought to be the projected axisymmetric (ASS) disk field as observed in face-on galaxies. Some galaxies addionionally exhibit strong vertical magnetic fields in the halo right above and below the central region of the disk. The mean-field dynamo theory in the disk cannot explain these observed fields without the action of a wind, which also probably plays an important role to keep the vertical scale heights constant in galaxies of different Hubble types and star formation activities, as has been observed in the radio continuum: At λ6 cm the vertical scale heights of the thin disk and the thick disk/halo in a sample of five edge-on galaxies are similar with a mean value of 300 +/- 50 pc for the thin disk and 1.8 +/- 0.2 kpc for the thick disk (a table and references are given in Krause 2011) with our sample including the brightest halo observed so far, NGC 253, with strong star formation, as well as one of the weakest halos, NGC 4565, with weak star formation. If synchrotron emission is the dominant loss process of the relativistic electrons the outer shape of the radio emission should be dumbbell-like as has been observed in several edge-on galaxies like e.g. NGC 253 (Heesen et al. 2009) and NGC 4565. As the synchrotron lifetime t syn at a single frequency is proportional to the total magnetic field strength B t -1.5, a cosmic ray bulk speed (velocity of a galactic wind) can be defined as v CR = h CR /t syn = 2 h z /t syn , where h CR and h z are the scale heights of the cosmic rays and the observed radio emission at this freqnency. Similar observed radio scale heights imply a self regulation mechanism between the galactic wind velocity, the total magnetic field strength and the star formation rate SFR in the disk: v CR ~ B t 1.5 ~ SFR ~ 0.5 (Niklas & Beck 1997).

A STELLAR MASS THRESHOLD FOR QUENCHING OF FIELD GALAXIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Geha, M.; Blanton, M. R.; Yan, R.

2012-09-20

We demonstrate that dwarf galaxies (10{sup 7} < M{sub stellar} < 10{sup 9} M{sub Sun }, -12 > M{sub r} > -18) with no active star formation are extremely rare (<0.06%) in the field. Our sample is based on the NASA-Sloan Atlas which is a reanalysis of the Sloan Digital Sky Survey Data Release 8. We examine the relative number of quenched versus star-forming dwarf galaxies, defining quenched galaxies as having no H{alpha} emission (EW{sub H{alpha}} < 2 A) and a strong 4000 A break. The fraction of quenched dwarf galaxies decreases rapidly with increasing distance from a massive host,more » leveling off for distances beyond 1.5 Mpc. We define galaxies beyond 1.5 Mpc of a massive host galaxy to be in the field. We demonstrate that there is a stellar mass threshold of M{sub stellar} < 1.0 Multiplication-Sign 10{sup 9} M{sub Sun} below which quenched galaxies do not exist in the field. Below this threshold, we find that none of the 2951 field dwarf galaxies are quenched; all field dwarf galaxies show evidence for recent star formation. Correcting for volume effects, this corresponds to a 1{sigma} upper limit on the quenched fraction of 0.06%. In more dense environments, quenched galaxies account for 23% of the dwarf population over the same stellar mass range. The majority of quenched dwarf galaxies (often classified as dwarf elliptical galaxies) are within 2 virial radii of a massive galaxy, and only a few percent of quenched dwarf galaxies exist beyond 4 virial radii. Thus, for galaxies with stellar mass less than 1.0 Multiplication-Sign 10{sup 9} M{sub Sun }, ending star formation requires the presence of a more massive neighbor, providing a stringent constraint on models of star formation feedback.« less

GAMA/H-ATLAS: the ultraviolet spectral slope and obscuration in galaxies

NASA Astrophysics Data System (ADS)

Wijesinghe, D. B.; da Cunha, E.; Hopkins, A. M.; Dunne, L.; Sharp, R.; Gunawardhana, M.; Brough, S.; Sadler, E. M.; Driver, S.; Baldry, I.; Bamford, S.; Liske, J.; Loveday, J.; Norberg, P.; Peacock, J.; Popescu, C. C.; Tuffs, R.; Andrae, E.; Auld, R.; Baes, M.; Bland-Hawthorn, J.; Buttiglione, S.; Cava, A.; Cameron, E.; Conselice, C. J.; Cooray, A.; Croom, S.; Dariush, A.; Dezotti, G.; Dye, S.; Eales, S.; Frenk, C.; Fritz, J.; Hill, D.; Hopwood, R.; Ibar, E.; Ivison, R.; Jarvis, M.; Jones, D. H.; van Kampen, E.; Kelvin, L.; Kuijken, K.; Maddox, S. J.; Madore, B.; Michałowski, M. J.; Nichol, B.; Parkinson, H.; Pascale, E.; Pimbblet, K. A.; Pohlen, M.; Prescott, M.; Rhodighiero, G.; Robotham, A. S. G.; Rigby, E. E.; Seibert, M.; Sergeant, S.; Smith, D. J. B.; Temi, P.; Sutherland, W.; Taylor, E.; Thomas, D.; van der Werf, P.

2011-08-01

We use multiwavelength data from the Galaxy And Mass Assembly (GAMA) and Herschel-ATLAS (H-ATLAS) surveys to compare the relationship between various dust obscuration measures in galaxies. We explore the connections between the ultraviolet (UV) spectral slope, β, the Balmer decrement and the far-infrared (FIR) to 150 nm far-ultraviolet (FUV) luminosity ratio. We explore trends with galaxy mass, star formation rate (SFR) and redshift in order to identify possible systematics in these various measures. We reiterate the finding of other authors that there is a large scatter between the Balmer decrement and the β parameter, and that β may be poorly constrained when derived from only two broad passbands in the UV. We also emphasize that FUV-derived SFRs, corrected for dust obscuration using β, will be overestimated unless a modified relation between β and the attenuation factor is used. Even in the optimum case, the resulting SFRs have a significant scatter, well over an order of magnitude. While there is a stronger correlation between the IR-to-FUV luminosity ratio and β parameter than with the Balmer decrement, neither of these correlations are particularly tight, and dust corrections based on β for high-redshift galaxy SFRs must be treated with caution. We conclude with a description of the extent to which the different obscuration measures are consistent with each other as well as the effects of including other galactic properties on these correlations.

Low Ionization Absorbing Gas Kinematics Around Z ~ 1 Galaxies

NASA Astrophysics Data System (ADS)

Churchill, C. W.; Steidel, C. C.; Vogt, S. S.

1996-12-01

Absorption profiles of the Mg II lambda lambda 2796,2803 doublet arising from gas associated with 48 ``normal'' intermediate redshift (0.4 < z < 1.7) galaxies have been resolved in QSO spectra at 6 km s(-1) resolution using HIRES on Keck I. We have found evidence for pronounced redshift evolution in the subcomponent velocity two--point correlation function, suggestive that the gas surrounding galaxies has settled over a 5--10 Gyr look--back time. Based upon a sub--sample of 15 galaxies at z<1, we found no evidence for correlations between the absorbing gas kinematics and the projected galactocentric distance of the gas, galaxy luminosities, or galaxy rest--frame colors (though trends between galaxy properties and absorption properties are apparent from a larger low resolution absorption line sample). The implication is that low ionization gas surrounding early epoch galaxies was not smoothly distributed either spatially or kinematically out to a galactocentric distance ~ 40 kpc. Directly from the profiles, we have measured the number of separate absorbing ``kinematic subsystems'' associated with each galaxy, and each subsystem's profile velocity width, asymmetry (skew), and integrated column density. The distribution in these subsystem properties with velocity is highly peaked at zero, and does not exhibit a bimodality. The lack of a bimodality is suggestive that the gas kinematics is not dominated by quasi--symmetric infall into galactic potential wells. In view of absorption line studies of local galaxies, it appears that extended regions of low ionization gas surrounding galaxies represent a dynamical and active epoch of ``normal'' galaxy evolution. The reservoirs of gas for these extended ``halos'' were probably residual infalling fragments (from earlier formation processes and on--going dynamical events) whose evolution first included a settling in velocity dispersion and then more recently a decline in number. The build up of thick and/or extended gaseous

The environmental dependence of H I in galaxies in the EAGLE simulations

NASA Astrophysics Data System (ADS)

Marasco, Antonino; Crain, Robert A.; Schaye, Joop; Bahé, Yannick M.; van der Hulst, Thijs; Theuns, Tom; Bower, Richard G.

2016-09-01

We use the EAGLE suite of cosmological hydrodynamical simulations to study how the H I content of present-day galaxies depends on their environment. We show that EAGLE reproduces observed H I mass-environment trends very well, while semi-analytic models typically overpredict the average H I masses in dense environments. The environmental processes act primarily as an on/off switch for the H I content of satellites with M* > 109 M⊙. At a fixed M*, the fraction of H I-depleted satellites increase with increasing host halo mass M200 in response to stronger environmental effects, while at a fixed M200 it decreases with increasing satellite M* as the gas is confined by deeper gravitational potentials. H I-depleted satellites reside mostly, but not exclusively, within the virial radius r200 of their host halo. We investigate the origin of these trends by focusing on three environmental mechanisms: ram pressure stripping by the intragroup medium, tidal stripping by the host halo and satellite-satellite encounters. By tracking back in time the evolution of the H I-depleted satellites, we find that the most common cause of H I removal is satellite encounters. The time-scale for H I removal is typically less than 0.5 Gyr. Tidal stripping occurs in haloes of M200 < 1014 M⊙ within 0.5 × r200, while the other processes act also in more massive haloes, generally within r200. Conversely, we find that ram pressure stripping is the most common mechanism that disturbs the H I morphology of galaxies at redshift z = 0. This implies that H I removal due to satellite-satellite interactions occurs on shorter time-scales than the other processes.

Blue compact dwarf galaxies. I - Neutral hydrogen observations of 115 galaxies

NASA Technical Reports Server (NTRS)

Thuan, T. X.; Martin, G. E.

1981-01-01

HI observations are reported for a sample of 115 blue compact dwarf (M sub B greater than approximately -18) galaxies or 'extragalactic H II regions' chosen mostly from the objective prism surveys of Markarian (1967-1974) and Haro (1956), with a few objects from Zwicky (1971) and other investigators. Ninety-three galaxies are detected. H I profiles, neutral hydrogen masses, total masses, and all available optical data are given for the 115 galaxies in a consistent and homogeneous system and in a useful format for statistical studies. The data are used in a companion paper to study the stochastic mode of star formation in galaxies.

JET PROPERTIES OF GeV-SELECTED RADIO-LOUD NARROW-LINE SEYFERT 1 GALAXIES AND POSSIBLE CONNECTION TO THEIR DISK AND CORONA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Xiao-Na; Lin, Da-Bin; Liang, En-Wei

The observed spectral energy distributions of five GeV-selected narrow-line Seyfert 1 (NLS1) galaxies are fitted with a model including the radiation ingredients from the relativistic jet, the accretion disk, and the corona. We compare the properties of these GeV NLS1 galaxies with flat spectrum radio quasars (FSRQs), BL Lacertae objects (BL Lacs), and radio-quiet (RQ) Seyfert galaxies, and explore possible hints for jet-disk/corona connection. Our results show that the radiation physics and the jet properties of the GeV NLS1 galaxies resemble that of FSRQs. The luminosity variations of PMN J0948+0022 and 1H 0323+342 at the GeV band is tightly correlatedmore » with the beaming factor (δ), similar to that observed in FSRQ 3C 279. The accretion disk luminosities and the jet powers of the GeV NLS1 galaxies cover both the ranges of FSRQs and BL Lacs. With the detection of bright corona emission in 1H 0323+342, we show that the ratio of the corona luminosity (L {sub corona}) to the accretion disk luminosity (L {sub d}) is marginally within the high end of this ratio distribution for an RQ Seyfert galaxy sample, and the variation of jet luminosity may connect with L {sub corona}. However, it is still unclear whether a system with a high L {sub corona}/L {sub d} ratio prefers to power a jet.« less

Scale dependence of galaxy biasing investigated by weak gravitational lensing: An assessment using semi-analytic galaxies and simulated lensing data

NASA Astrophysics Data System (ADS)

Simon, Patrick; Hilbert, Stefan

2018-05-01

Galaxies are biased tracers of the matter density on cosmological scales. For future tests of galaxy models, we refine and assess a method to measure galaxy biasing as a function of physical scale k with weak gravitational lensing. This method enables us to reconstruct the galaxy bias factor b(k) as well as the galaxy-matter correlation r(k) on spatial scales between 0.01 h Mpc-1 ≲ k ≲ 10 h Mpc-1 for redshift-binned lens galaxies below redshift z ≲ 0.6. In the refinement, we account for an intrinsic alignment of source ellipticities, and we correct for the magnification bias of the lens galaxies, relevant for the galaxy-galaxy lensing signal, to improve the accuracy of the reconstructed r(k). For simulated data, the reconstructions achieve an accuracy of 3-7% (68% confidence level) over the above k-range for a survey area and a typical depth of contemporary ground-based surveys. Realistically the accuracy is, however, probably reduced to about 10-15%, mainly by systematic uncertainties in the assumed intrinsic source alignment, the fiducial cosmology, and the redshift distributions of lens and source galaxies (in that order). Furthermore, our reconstruction technique employs physical templates for b(k) and r(k) that elucidate the impact of central galaxies and the halo-occupation statistics of satellite galaxies on the scale-dependence of galaxy bias, which we discuss in the paper. In a first demonstration, we apply this method to previous measurements in the Garching-Bonn Deep Survey and give a physical interpretation of the lens population.

Stellar Photometric Structures of the Host Galaxies of Nearby Type 1 Active Galactic Nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Minjin; Ho, Luis C.; Peng, Chien Y.

2017-10-01

We present detailed image analysis of rest-frame optical images of 235 low-redshift ( z ≲ 0.35) Type 1 active galactic nuclei (AGNs) observed with the Hubble Space Telescope . The high-resolution images enable us to perform rigorous two-dimensional image modeling to decouple the luminous central point source from the host galaxy, which, when warranted, is further decomposed into its principal structural components (bulge, bar, and disk). In many cases, care must be taken to account for structural complexities such as spiral arms, tidal features, and overlapping or interacting companion galaxies. We employ Fourier modes to characterize the degree of asymmetrymore » of the light distribution of the stars as a quantitative measure of morphological distortion due to interactions or mergers. We examine the dependence of the physical parameters of the host galaxies on the properties of the AGNs, namely, radio-loudness and the width of the broad emission lines. In accordance with previous studies, narrow-line (H β FWHM ≤ 2000 km s{sup −1}) Type 1 AGNs, in contrast to their broad-line (H β FWHM > 2000 km s{sup −1}) counterparts, are preferentially hosted in later-type, lower-luminosity galaxies, which have a higher incidence of pseudo-bulges, are more frequently barred, and are less morphologically disturbed. This suggests that narrow-line Type 1 AGNs experienced a more quiescent evolutionary history driven primarily by internal secular evolution instead of external dynamical perturbations. The fraction of AGN hosts showing merger signatures is larger for more luminous sources. Radio-loud AGNs generally preferentially live in earlier-type (bulge-dominated), more massive hosts, although a minority of them appear to contain a significant disk component. We do not find convincing evidence for enhanced merger signatures in the radio-loud population.« less

Spatially Resolved Spectroscopy of Narrow-line Seyfert 1 Host Galaxies

NASA Astrophysics Data System (ADS)

Scharwächter, J.; Husemann, B.; Busch, G.; Komossa, S.; Dopita, M. A.

2017-10-01

We present optical integral field spectroscopy for five z< 0.062 narrow-line Seyfert 1 (NLS1) galaxies, probing their host galaxies at ≳ 2{--}3 {kpc} scales. Emission lines from the active galactic nucleus (AGN) and the large-scale host galaxy are analyzed separately, based on an AGN-host decomposition technique. The host galaxy gas kinematics indicates large-scale gas rotation in all five sources. At the probed scales of ≳ 2{--}3 {kpc}, the host galaxy gas is found to be predominantly ionized by star formation without any evidence of a strong AGN contribution. None of the five objects shows specific star formation rates (SFRs) exceeding the main sequence of low-redshift star-forming galaxies. The specific SFRs for MCG-05-01-013 and WPVS 007 are roughly consistent with the main sequence, while ESO 399-IG20, MS 22549-3712, and TON S180 show lower specific SFRs, intermediate to the main sequence and the red quiescent galaxies. The host galaxy metallicities, derived for the two sources with sufficient data quality (ESO 399-IG20 and MCG-05-01-013), indicate central oxygen abundances just below the low-redshift mass-metallicity relation. Based on this initial case study, we outline a comparison of AGN and host galaxy parameters as a starting point for future extended NLS1 studies with similar methods.

Galaxy Formation through Filamentary Accretion at z = 6.1

NASA Astrophysics Data System (ADS)

Jones, G. C.; Willott, C. J.; Carilli, C. L.; Ferrara, A.; Wang, R.; Wagg, J.

2017-08-01

We present Atacama Large Millimeter/submillimeter Array observations of the dust continuum and [C II] 158 μm line emission from the z = 6.0695 Lyman-Break Galaxy (LBG) WMH5. These observations at 0.″3 spatial resolution show a compact (˜3 kpc) main galaxy in dust and [C II] emission, with a “tail” of emission extending to the east by about 5 kpc (in projection). The [C II] tail is comprised predominantly of two distinct sub-components in velocity, separated from the core by ˜100 and 250 km s-1, with narrow intrinsic widths of about 80 km s-1, which we call “sub-galaxies.” The sub-galaxies themselves are extended east-west by about 3 kpc in individual channel images. The [C II] tail joins smoothly into the main galaxy velocity field. The [C II] line to continuum ratios are comparable for the main and sub-galaxy positions, within a factor two. In addition, these ratios are comparable to z˜ 5.5 LBGs. We conjecture that the WMH5 system represents the early formation of a galaxy through the accretion of smaller satellite galaxies, embedded in a smoother gas distribution, along a possibly filamentary structure. The results are consistent with current cosmological simulations of early galaxy formation and support the idea of very early enrichment with dust and heavy elements of the accreting material.

ACTN3 R577X genotype and performance of elite middle-long distance swimmers in China

PubMed Central

Li, YC; Wang, LQ; Yi, LY; Liu, JH; Lu, YF; Wang, M

2016-01-01

The ACTN3 gene is one of the genes that have a potential influence on physical performance. Studies have shown that the 577R genotype of ACTN3 is more prevalent in sprint athletes, while the 577X genotype is more prevalent in endurance athletes. In swimming, both power and endurance related phenotypes are equally needed for swimmers to excel at the elite level. Therefore, the ACTN3 R577X polymorphism may become a genetic marker for swimmers. The study aimed to examine the association of the ACTN3 R577X genotype with the performance of elite middle-long distance (MLD) swimmers. The distributions of the ACTN3 R577X (rs1815739) genotype and allele were examined in a general population (206) and a group of elite MLD swimmers (160) in China by using PCR-RFLP and TOF. Compared with the general population, the elite MLD swimmers, especially the females, had a higher frequency of the RR genotype. The swimmers had a higher frequency of the R allele than the general population. However, the difference was not statistically significant. After being stratified by performance, the difference of the R allele frequency between the international master athletes and the general population was statistically significant. The elite MLD swimmers had a higher frequency of the RR genotype than the RX+XX genotype compared with the general population. The ACTN3 R577X polymorphism was associated with the performance of elite MLD swimmers in China. The SNP R577X could be used as a biomarker for selecting elite MLD swimmers in China. PMID:28416896

ACTN3 R577X polymorphism and team-sport performance: a study involving three European cohorts.

PubMed

Eynon, Nir; Banting, Lauren K; Ruiz, Jonatan R; Cieszczyk, Pawel; Dyatlov, Dmitry A; Maciejewska-Karlowska, Agnieszka; Sawczuk, Marek; Pushkarev, Vladimir P; Kulikov, Leonid M; Pushkarev, Evgeny D; Femia, Pedro; Stepto, Nigel K; Bishop, David J; Lucia, Alejandro

2014-01-01

To determine the association between the α-actinin-3 (ACTN3) R577X polymorphism and elite team-sport athletic status in three cohorts of European team-sport athletes. We compared the genotype and allele frequencies of the ACTN3 R577X (rs1815739) polymorphisms between team-sport athletes (n=205), endurance athletes (n=305), sprint/power athletes (n=378), and non-athletic controls (n=568) from Poland, Russia and Spain; all participants were unrelated European men. Genomic DNA was extracted from either buccal epithelium or peripheral blood using a standard protocol. Genotyping was performed using several methods, and the results were replicated following recent recommendations for genotype-phenotype association studies. Genotype distributions of all control and athletic groups met Hardy-Weinberg equilibrium (all p>0.05). Team-sport athletes were less likely to have the 577RR genotype compared to the 577XX genotype than sprint/power athletes [odds ratio: 0.58, 95% confidence interval: 0.34-0.39, p=0.045]. However, the ACTN3 R577X polymorphism was not associated with team-sports athletic status, compared to endurance athletes and non-athletic controls. Furthermore, no association was observed for any of the genotypes with respect to the level of competition (elite vs. national level). The ACTN3 R577X polymorphism was not associated with team-sport athletic status, compared to endurance athletes and non-athletic controls, and the observation that the 577RR genotype is overrepresented in power/sprint athletes compared with team-sport athletes needs to be confirmed in future studies. Copyright © 2013 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Revealing H I gas in emission and absorption on pc to kpc scales in a galaxy at z ˜ 0.017

NASA Astrophysics Data System (ADS)

Gupta, N.; Srianand, R.; Farnes, J. S.; Pidopryhora, Y.; Vivek, M.; Paragi, Z.; Noterdaeme, P.; Oosterloo, T.; Petitjean, P.

2018-05-01

We present a detailed study of the quasar-galaxy pair: J1243+4043-UGC 07904. The sight line of the background quasar ( zq = 1.5266) passes through a region of the galaxy (zg = 0.0169) at an impact parameter of 6.9 kpc with high metallicity (0.5 Z⊙) and negligible dust extinction. We detect H I 21-cm absorption from the foreground galaxy at arcsecond and milliarcsecond scales. For typical cold neutral medium (CNM) temperatures in the Milky Way, this 21-cm absorber can be classified as a damped Lyα absorber (DLA). We infer the harmonic mean spin temperature of the gas to be ˜400 K and for a simple two-phase medium we estimate the CNM fraction to be fCNM = 0.27. This is remarkably consistent with the CNM fraction observed in the Galaxy and less than that of high-redshift DLAs. The quasar exhibits a core-jet morphology on milliarcsecond scales, corresponding to an overall extent of ˜9 pc at zg. We show that the size of CNM absorbing clouds associated with the foreground galaxy is >5 pc and they may be part of cold gas structures that extend beyond ˜35 pc. Interestingly, the rotation measure of quasar J1243+4043 is higher than any other source in samples of quasars with high-z DLAs. However, we do not find any detectable differences in rotation measures and polarization fraction of sight lines with or without high-z (z ≥ 2) DLAs or low-z (z ≤ 0.3) 21-cm absorbers. Finally, the foreground galaxy UGC 07904 is also part of a galaxy group. We serendipitously detect H I 21-cm emission from four members of the group, and an ˜80 kpc long H I bridge connecting two of the other members. The latter, together with the properties of the group members, suggests that the group is a highly interactive environment.

The Cambridge-Cambridge x-ray serendipity survey. 2: Classification of x-ray luminous galaxies

NASA Technical Reports Server (NTRS)

Boyle, B. J.; Mcmahon, R. G.; Wilkes, B. J.; Elvis, Martin

1994-01-01

We present the results of an intermediate-resolution (1.5 A) spectroscopic study of 17 x-ray luminous narrow emission-line galaxies previously identified in the Cambridge-Cambridge ROSAT Serendipity Survey and the Einstein Extended Medium Sensitivity Survey. Emission-line ratios reveal that the sample is composed of ten Seyfert and seven starburst galaxies. Measured linewidths for the narrow H alpha emission lines lie in the range 170 - 460 km s(exp -1). Five of the objects show clear evidence for asymmetry in the (OIII) lambda 5007 emission-line profile. Broad H alpha emission is detected in six of the Seyfert galaxies, which range in type from Seyfert 1.5 to 2. Broad H beta emission is only detected in one Seyfert galaxy. The mean full width at half maximum for the broad lines in the Seyfert galaxies is FWHM = 3900 +/- 1750 km s(exp -1). Broad (FWHM = 2200 +/- 600 km s(exp -1) H alpha emission is also detected in three of the starburst galaxies, which could originate from stellar winds or supernovae remnants. The mean Balmer decrement for the sample is H alpha / H beta = 3, consistent with little or no reddening for the bulk of the sample. There is no evidence for any trend with x-ray luminosity in the ratio of starburst galaxies to Seyfert galaxies. Based on our previous observations, it is therefore likely that both classes of object comprise approximately 10 percent of the 2 keV x-ray background.

Neutral hydrogen gas, past and future star formation in galaxies in and around the ‘Sausage’ merging galaxy cluster

DOE PAGES

Stroe, Andra; Oosterloo, Tom; Rottgering, Huub J. A.; ...

2015-07-25

CIZA J2242.8+5301 (z = 0.188, nicknamed ‘Sausage’) is an extremely massive (M 200 ~2.0 × 10 15 M ⊙), merging cluster with shock waves towards its outskirts, which was found to host numerous emission line galaxies. We performed extremely deep Westerbork Synthesis Radio Telescope H i observations of the ‘Sausage’ cluster to investigate the effect of the merger and the shocks on the gas reservoirs fuelling present and future star formation (SF) in cluster members. By using spectral stacking, we find that the emission line galaxies in the ‘Sausage’ cluster have, on average, as much H i gas as fieldmore » galaxies (when accounting for the fact cluster galaxies are more massive than the field galaxies), contrary to previous studies. Since the cluster galaxies are more massive than the field spirals, they may have been able to retain their gas during the cluster merger. The large H i reservoirs are expected to be consumed within ~0.75–1.0 Gyr by the vigorous SF and active galactic nuclei activity and/or driven out by the outflows we observe. We find that the star formation rate (SFR) in a large fraction of H α emission line cluster galaxies correlates well with the radio broad-band emission, tracing supernova remnant emission. This suggests that the cluster galaxies, all located in post-shock regions, may have been undergoing sustained SFR for at least 100 Myr. In conclusion, this fully supports the interpretation proposed by Stroe et al. and Sobral et al. that gas-rich cluster galaxies have been triggered to form stars by the passage of the shock.« less

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.

The kinematics and morphology of cool galactic winds and halo gas from galaxies at 0.3 < z < 1.4

NASA Astrophysics Data System (ADS)

Rubin, Kate H. R.

galaxy for outflows to be driven by either radiation pressure or thermalized energy from supernovae. To test this directly, we use a similar technique to probe cool gas kinematics in the individual Keck/LRIS spectra of a sample of ˜120 galaxies at 0.3 < z < 1.4. These data permit modeling of Mg II and Fe II absorption lines to obtain, e.g., the cool gas outflow velocity and covering fraction. Using Spitzer/MIPS and GALEX imaging to determine SFRs in concert with HST/ACS imaging which enables measurements of the size of star-forming regions, we compare outflow velocity to SigmaSFR. We find that while we detect outflows over a range 0.005 M⊙ yr-1 kpc-2 < Sigma SFR < 1 M⊙ yr-1 kpc-2, outflows occur more frequently with increasing SigmaSFR. The absorption line studies described above provide strong constraints on, e.g., the cool gas velocities. However, they provide only weak constraints on the radial extent and morphology of the gas. Knowledge of the spatial extent of the outflow is essential for accurately estimating its mass and energy; measurements of these rates are in turn crucial to understanding the role of outflows in driving galaxy evolution. Next, we show that emission in Mg II and Fe II* fine-structure lines can provide novel constraints on the spatial extent of an outflow. We identify a starburst galaxy at z = 0.69 which exhibits emission and absorption in Mg II, yielding a P Cygni-like line profile. We demonstrate that this emission is spatially broader than the continuum emission and the emission from H II regions, and associate the Mg II and Fe II* emission with resonance-line scattering and fluorescence in the outflow. These features are common at z ˜ 1, and in principle yield the first direct constraint on the radial extent of the outflow in many distant galaxies. Finally, we present a study of the cool gas around a single galaxy at z = 0.47 using spectroscopy of a bright background galaxy at z = 0.7 at a transverse distance of 16.5 h-170 kpc. While

49 CFR 236.577 - Test, acknowledgement, and cut-in circuits.

Code of Federal Regulations, 2011 CFR

2011-10-01

... INSTALLATION, INSPECTION, MAINTENANCE, AND REPAIR OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCES Automatic Train Stop, Train Control and Cab Signal Systems Inspection and Tests; Roadway § 236.577 Test...

Quantifying Bursty Star Formation and Dust Extinction in Dwarf Galaxies at 0.75 < z < 1.5

NASA Astrophysics Data System (ADS)

Siana, Brian

2014-10-01

Using the magnification provided by gravitational lensing, our team has recently uncovered an important population of star-forming dwarf galaxies at 1galaxies are claimed to be significantly different from their more massive counterparts, but uncertainties remain. First, the star formation rates of these dwarf galaxies are expected to vary by an order of magnitude on short, 10-30 Myr, time scales unlike the more massive galaxies. Second, the dust extinction is claimed to be very low, but these claims have not considered that the intrinsic colors of these galaxies are likely very different than more massive galaxies.In cycle 21, we were awarded 48 orbits of near-UV imaging of the three best Frontier Field cluster lenses to measure the ultraviolet properties of a large number of star-forming dwarf galaxies. Also in cycle 21, the GLASS survey was allocated 140 orbits of WFC3/IR grism spectroscopy of 10 lensing clusters, including 42 orbits of spectroscopy in the Frontier Fields for which we have near-UV imaging. We propose for archival funding to incorporate the WFC3/IR grism spectroscopy of a sample of 70 dwarf galaxies at 0.751.5 in the three Frontier Fields with deep near-UV imaging. Together, the UV and H-alpha luminosities will determine star formation rates on very different timescales, allowing us to quantify the "burstiness'' in these dwarf galaxies. Furthermore, both the UV spectral slope and the Balmer decrement {Halpha/Hbeta ratio} will allow independent measures of dust extinction, to better quantify the intrinsic star formation rates in these galaxies.

Simulations of deep galaxy fields. 1: Monte Carlo simulations of optical and near-infrared counts

NASA Technical Reports Server (NTRS)

Chokshi, Arati; Lonsdale, Carol J.; Mazzei, Paola; De Zotti, Gianfranco

1994-01-01

Monte Carlo simulations of three-dimensional galaxy distributions are performed, following the 1988 prescription of Chokshi & Wright, to study the photometric properties of evolving galaxy populations in the optical and near-infrared bands to high redshifts. In this paper, the first of a series, we present our baseline model in which galaxy numbers are conserved, and in which no explicit 'starburst' population is included. We use the model in an attempt to simultaneously fit published blue and near-infrared photometric and spectroscopic observations of deep fields. We find that our baseline models, with a formation redshift, z(sub f), of 1000, and H(sub 0) = 50, are able to reproduce the blue counts to b(sub j) = 22, independent of the value of Omega(sub 0), and also to provide a satisfactory fit to the observed blue-band redshift distributions, but for no value of Omega(sub 0) do we achieve an acceptable fit to the fainter blue counts. In the K band, we fit the number counts to the limit of the present-day surveys only for an Omega(sub 0) = 0 cosmology. We investigate the effect on the model fits of varying the cosmological parameters H(sub 0), the formation red-shift z(sub f), and the local luminosity function. Changing H(sub 0) does not improve the fits to the observations. However, reducing the epoch of a galaxy formation used in our simulations has a substantial effect. In particular, a model with z(sub f) approximately equal to 5 in a low Omega(sub 0) universe improves the fit to the faintest photometric blue data without any need to invoke a new population of galaxies, substantial merging, or a significant starburst galaxy population. For an Omega(sub 0) = 1 universe, however, reducing z(sub f) is less successful at fitting the blue-band counts and has little effect at all at K. Varying the parameters of the local luminosity function can also have a significant effect. In particular the steep low end slope of the local luminosity function of Franceschini et

Infalling groups and galaxy transformations in the cluster A2142

NASA Astrophysics Data System (ADS)

Einasto, Maret; Deshev, Boris; Lietzen, Heidi; Kipper, Rain; Tempel, Elmo; Park, Changbom; Gramann, Mirt; Heinämäki, Pekka; Saar, Enn; Einasto, Jaan

2018-03-01

Context. Superclusters of galaxies provide dynamical environments for the study of the formation and evolution of structures in the cosmic web from galaxies, to the richest galaxy clusters, and superclusters themselves. Aims: We study galaxy populations and search for possible merging substructures in the rich galaxy cluster A2142 in the collapsing core of the supercluster SCl A2142, which may give rise to radio and X-ray structures in the cluster, and affect galaxy properties of this cluster. Methods: We used normal mixture modelling to select substructure of the cluster A2142. We compared alignments of the cluster, its brightest galaxies (hereafter BCGs), subclusters, and supercluster axes. The projected phase space (PPS) diagram and clustercentric distributions are used to analyse the dynamics of the cluster and study the distribution of various galaxy populations in the cluster and subclusters. Results: We find several infalling galaxy groups and subclusters. The cluster, supercluster, BCGs, and one infalling subcluster are all aligned. Their orientation is correlated with the alignment of the radio and X-ray haloes of the cluster. Galaxy populations in the main cluster and in the outskirts subclusters are different. Galaxies in the centre of the main cluster at the clustercentric distances 0.5 h-1 Mpc (Dc/Rvir < 0.5, Rvir = 0.9 h-1 Mpc) have older stellar populations (with the median age of 10-11 Gyr) than galaxies at larger clustercentric distances. Star-forming and recently quenched galaxies are located mostly at the clustercentric distances Dc ≈ 1.8 h-1 Mpc, where subclusters fall into the cluster and the properties of galaxies change rapidly. In this region the median age of stellar populations of galaxies is about 2 Gyr. Galaxies in A2142 on average have higher stellar masses, lower star formation rates, and redder colours than galaxies in rich groups. The total mass in infalling groups and subclusters is M ≈ 6 × 1014 h-1 M⊙, that is approximately

Galaxy And Mass Assembly (GAMA): The mechanisms for quiescent galaxy formation at z < 1

NASA Astrophysics Data System (ADS)

Rowlands, K.; Wild, V.; Bourne, N.; Bremer, M.; Brough, S.; Driver, S. P.; Hopkins, A. M.; Owers, M. S.; Phillipps, S.; Pimbblet, K.; Sansom, A. E.; Wang, L.; Alpaslan, M.; Bland-Hawthorn, J.; Colless, M.; Holwerda, B. W.; Taylor, E. N.

2018-01-01

One key problem in astrophysics is understanding how and why galaxies switch off their star formation, building the quiescent population that we observe in the local Universe. From the Galaxy And Mass Assembly and VIsible MultiObject Spectrograph Public Extragalactic Redshift surveys, we use spectroscopic indices to select quiescent and candidate transition galaxies. We identify potentially rapidly transitioning post-starburst (PSB) galaxies and slower transitioning green-valley galaxies. Over the last 8 Gyr, the quiescent population has grown more slowly in number density at high masses ({M}_\\ast >10^{11}{M_{⊙}) than at intermediate masses ({M}_\\ast >10^{10.6}{M_{⊙}). There is evolution in both the PSB and green-valley stellar mass functions, consistent with higher mass galaxies quenching at earlier cosmic times. At intermediate masses ({M}_\\ast >10^{10.6}{M_{⊙}), we find a green-valley transition time-scale of 2.6 Gyr. Alternatively, at z ∼ 0.7, the entire growth rate could be explained by fast-quenching PSB galaxies, with a visibility time-scale of 0.5 Gyr. At lower redshift, the number density of PSBs is so low that an unphysically short visibility window would be required for them to contribute significantly to the quiescent population growth. The importance of the fast-quenching route may rapidly diminish at z < 1. However, at high masses ({M}_\\ast >10^{11}{M_{⊙}), there is tension between the large number of candidate transition galaxies compared to the slow growth of the quiescent population. This could be resolved if not all high-mass PSB and green-valley galaxies are transitioning from star forming to quiescent, for example if they rejuvenate out of the quiescent population following the accretion of gas and triggering of star formation, or if they fail to completely quench their star formation.

On the determination of the number of O stars in H II regions and starburst galaxies

NASA Technical Reports Server (NTRS)

Vacca, William D.

1994-01-01

The hot star population in H II regions, H II galaxies, and starburst galaxies is often described in terms of the number of 'equivalent' O stars of a single representative subtype and luminosity class needed to produce the ionizing luminosity deduced from the nebular recombination lines in the optical spectra. In this paper we define conversion factors eta(sub 0), eta(sub 1), and zeta(sub 5000) with which the total number of O V stars and their flux contribution at 5000 A can be derived from the number of these 'equivalent' stars. These quantities depend primarily on three parameters: the slope and upper mass limit of the stellar mass function and the metallicity of the region. Using the latest stellar atmosphere and evolution models, we calculate eta(sub 0), eta(sub 1), and zeta(sub 5000) for a large number of values of these parameters. The results are presented in tabular as well as graphical form. We apply our results to two H II regions for which the hot star population are known and find that the predicted numbers of O stars agree well the observed counts. In addition, we describe a method by which the values of eta(sub 0) and eta(sub 1) and the observed emission-line fluxes can be used to place constraints on the allowed values of the slope and upper mass limit of the stellar mass function in a region.

Imaging of diffuse H I absorption structure in the SSA22 protocluster region at z = 3.1

NASA Astrophysics Data System (ADS)

Mawatari, Ken; Inoue, Akio K.; Yamada, Toru; Hayashino, Tomoki; Otsuka, Takuya; Matsuda, Yuichi; Umehata, Hideki; Ouchi, Masami; Mukae, Shiro

2017-06-01

Using galaxies as background light sources to map intervening Ly α absorption is a novel approach to study the interplay among galaxies, the circumgalactic medium (CGM) and the intergalactic medium. Introducing a new measure of z = 3.1 H I Ly α absorption relative to the cosmic mean, ΔNB497, estimated from photometric data of star-forming galaxies at 3.3 ≲ z ≲ 3.5, we have made two-dimensional ΔNB497 maps in the z = 3.1 SSA22 protocluster region and two control fields (Subaru/XMM-Newton Deep Survey; Great Observatory Optical Deep Survey North) with a spatial resolution of ˜5 comoving Mpc. The ΔNB497 measurements in the SSA22 field are systematically larger than those in the control fields, and this H I absorption enhancement extends more than 50 comoving Mpc. The field-averaged (I.e. ˜50 comoving Mpc scale) ΔNB497 and the overdensity of Ly α emitters (LAEs) seem to be correlated, while there is no clear dependency of the ΔNB497 on the local LAE overdensity in a few comoving Mpc scale. These results suggest that diffuse H I gas spreads out in/around the SSA22 protocluster. We have also found an enhancement of ΔNB497 at a projected distance <100 physical kpc from the nearest z = 3.1 galaxies at least in the SSA22 field, which is probably due to H I gas associated with the CGM of individual galaxies. The H I absorption enhancement in the CGM-scale tends to be weaker around galaxies with stronger Ly α emission, which suggests that the Ly α escape fraction from galaxies depends on hydrogen neutrality in the CGM.

The Taxonomy of Blue Amorphous Galaxies. I. Hα and UBVI Data

NASA Astrophysics Data System (ADS)

Marlowe, Amanda T.; Meurer, Gerhardt R.; Heckman, Timothy M.; Schommer, Robert

1997-10-01

Dwarf galaxies play an important role in our understanding of galaxy formation and evolution. We have embarked on a systematic study of 12 nearby dwarf galaxies (most of which have been classified as amorphous) selected preferentially by their blue colors. The properties of the galaxies in the sample suggest that they are in a burst or postburst state. It seems likely that these amorphous galaxies are closely related to other ``starburst'' dwarfs such as blue compact dwarfs (BCDs) and H II galaxies but are considerably closer and therefore easier to study. If so, these galaxies may offer important insights into dwarf galaxy evolution. In an effort to clarify the role of starbursts in evolutionary scenarios for dwarf galaxies, we present Hα and UBVI data for our sample. Blue amorphous galaxies, like BCDs and H II galaxies, have surface brightness profiles that are exponential in the outer regions (r >~ 1.5re) but have a predominantly blue central excess, which suggests a young burst in an older, redder galaxy. Seven of the galaxies have the bubble or filamentary Hα morphology and double-peaked emission lines that are the signature of superbubbles or superwind activity. These galaxies are typically the ones with the strongest central excesses. The underlying exponential galaxies are very similar to those found in BCDs and H II galaxies. How amorphous galaxies fit into the dwarf irregular-``starburst dwarf''-dwarf elliptical evolutionary debate is less clear. In this paper, we present our data and make some preliminary comparisons between amorphous galaxies and other classes of dwarf galaxies. In a future companion paper, we will compare this sample more quantitatively with other dwarf galaxy samples in an effort to determine if amorphous galaxies are a physically different class of object from other starburst dwarfs such as BCDs and H II galaxies and also investigate their place in dwarf galaxy evolution scenarios.

Outflows in low-mass galaxies at z >1

NASA Astrophysics Data System (ADS)

Maseda, Michael V.; MUSE GTO Consortium

2017-03-01

Star formation histories of local dwarf galaxies, derived through resolved stellar populations, appear complex and varied. The general picture derived from hydrodynamical simulations is one of cold gas accretion and bursty star formation, followed by feedback from supernovae and winds that heat and eject the central gas reservoirs. This ejection halts star formation until the material cools and re-accretes, resulting in an episodic SFH, particularly at stellar masses below ~ 109 M⊙. Such feedback has often been cited as the driving force behind the observed slowly-rising rotation curves in local dwarfs, due to an under-density of dark matter compared to theoretical models, which is one of the primary challenges to LCDM cosmology. However, these events have not yet been directly observed at high-redshift. Recently, using HST imaging and grism spectroscopy, we have uncovered an abundant population of low-mass galaxies (M* < 109 M⊙) at z = 1 - 2 that are undergoing strong bursts of star formation, in agreement with the theoretical predictions. These Extreme Emission Line Galaxies, with high specific SFRs and shallow gravitational potential wells, are ideal places to test the theoretical prediction of strong feedback-driven outflows. Here we use deep MUSE spectroscopy to search these galaxies for signatures of outflowing material, namely kinematic offsets between absorption lines (in the restframe optical and UV), which trace cool gas, and the nebular emission lines, which define the systemic redshift of the galaxy. Although the EELGs are intrinsically very faint, stacked spectra reveal blueshifted velocity centroids for Fe II absorption, which is indicative of outflowing cold gas. This represents the first constraint on outflows in M* < 109 M⊙ galaxies at z = 1 - 2. These outflows should regulate the star formation histories of low-mass galaxies at early cosmic times and thus play a crucial role in galaxy growth and evolution.

40 CFR 180.577 - Bispyribac-sodium; tolerances for residues.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 25 2013-07-01 2013-07-01 false Bispyribac-sodium; tolerances for... § 180.577 Bispyribac-sodium; tolerances for residues. (a) General. Tolerances are established for residues of the herbicide bispyribac-sodium, including its metabolites and degradates, in or on the...

A Recollimation Shock in a Stationary Jet Feature with Limb-brightening in the Gamma-Ray-emitting Narrow-line Seyfert 1 Galaxy 1H 0323+342

NASA Astrophysics Data System (ADS)

Doi, Akihiro; Hada, Kazuhiro; Kino, Motoki; Wajima, Kiyoaki; Nakahara, Satomi

2018-04-01

We report the discovery of a local convergence of a jet cross section in the quasi-stationary jet feature in the γ-ray-emitting narrow-line Seyfert 1 galaxy (NLS1) 1H 0323+342. The convergence site is located at ∼7 mas (corresponding to the order of 100 pc in deprojection) from the central engine. We also found limb-brightened jet structures at both the upstream and downstream of the convergence site. We propose that the quasi-stationary feature showing the jet convergence and limb-brightening occurs as a consequence of recollimation shock in the relativistic jets. The quasi-stationary feature is one of the possible γ-ray-emitting sites in this NLS1, in analogy with the HST-1 complex in the M87 jet. Monitoring observations have revealed that superluminal components passed through the convergence site and the peak intensity of the quasi-stationary feature, which showed apparent coincidences with the timing of observed γ-ray activities.

Photoionization of disk galaxies: An explanation of the sharp edges in the H I distribution

NASA Technical Reports Server (NTRS)

Dove, James B.; Shull, J. Michael

1994-01-01

We have reproduced the observed radial truncation of the H I distribution in isolated spiral galaxies with a model in which extragalactic radiation photoionizes the gaseous disk. For a galactic mass distribution model that reproduces the observed rotation curves, including dark matter in the disk and halo, the vertical structure of the gas is determined self-consistently. The ionization structure and column densities of H and He ions are computed by solving the radiation transfer equation for both continuum and lines. Our model is similar to that of Maloney, and the H I structure differs by less than 10%. The radial structure of the column density of H I is found to be more sensitive to the extragalactic radiation field than to the distribution of mass. For this reason, considerable progress can be made in determining the extragalactic flux of ionizing photons, phi(sub ex), with more 21 cm observations of isolated galaxies. However, owing to the uncertainty of the radial distribution of total hydrogen at large radii, inferring the extragalactic flux by comparing the observed edges to photoionization models is somewhat subjective. We find 1 x 10(exp 4)/sq cm/s is less than or approximately phi(sub ex) is less than or approximately 5 x 10(exp 4)/sq cm/s, corresponding to 2.1 is less than or approximately iota(sub 0) is less than or approximately 10.5 x 10(exp -23) ergs/sq cm/s/Hz/sr for a 1/nu spectrum. Although somewhat higher, our inferred range of iota(sub 0) is consistent with the large range of values obtained by Kulkarni & Fall from the 'proximity effect' toward Quasi-Stellar Objects (QSOs) at approximately 0.5.

Activity of the Seyfert galaxy neighbours

NASA Astrophysics Data System (ADS)

Koulouridis, E.; Plionis, M.; Chavushyan, V.; Dultzin, D.; Krongold, Y.; Georgantopoulos, I.; León-Tavares, J.

2013-04-01

We present a follow-up study of a series of papers concerning the role of close interactions as a possible triggering mechanism of AGN activity. We have already studied the close (≤100 h-1 kpc) and the large-scale (≤1 h-1 Mpc) environment of a local sample of Sy1, Sy2, and bright IRAS galaxies (BIRG) and of their respective control samples. The results led us to the conclusion that a close encounter appears capable of activating a sequence where an absorption line galaxy (ALG) galaxy first becomes a starburst, then a Sy2, and finally a Sy1. Here we investigate the activity of neighbouring galaxies of different types of AGN, since both galaxies of an interacting pair should be affected. To this end we present the optical spectroscopy and X-ray imaging of 30 neighbouring galaxies around two local (z ≲ 0.034) samples of 10 Sy1 and 13 Sy2 galaxies. Although this is a pilot study of a small sample, various interesting trends have been discovered that imply physical mechanisms that may lead to different Seyfert types. Based on the optical spectroscopy, we find that more than 70% of all neighbouring galaxies exhibit star forming and/or nuclear activity (namely recent star formation and/or AGN), while an additional X-ray analysis showed that this percentage might be significantly higher. Furthermore, we find a statistically significant correlation, at a 99.9% level, between the value of the neighbour's [OIII]/Hβ ratio and the activity type of the central active galaxy, i.e. the neighbours of Sy2 galaxies are systematically more ionized than the neighbours of Sy1s. This result, in combination with trends found using the Equivalent Width of the Hα emission line and the stellar population synthesis code STARLIGHT, indicate differences in the stellar mass, metallicity, and star formation history between the samples. Our results point towards a link between close galaxy interactions and activity and also provide more clues regarding the possible evolutionary sequence

The molecular cloud content of early type galaxies

NASA Technical Reports Server (NTRS)

Wiklind, Tommy; Henkel, Christian

1990-01-01

A survey of the CO content of early type galaxies led to 24 new detections, mostly lenticular galaxies. The galaxies, which are situated in both the Northern and Southern Hemispheres, were selected as being far-IR luminous compared to their blue luminosity, and situated at distances less than about 50 Mpc (H sub o=100 km/s Mpc(-1). Results for some early galaxies (NGC 404, NGC 3593 and NGC 4369 are given.

The ZEUS 1 & 2 INvestigated Galaxy Reference Sample (ZINGRS): A window into galaxies in the early Universe.

NASA Astrophysics Data System (ADS)

Ferkinhoff, Carl; Hershey, Deborah; Scrabeck, Alex; Higdon, Sarah; Higdon, James L.; Tidwell, Hannah; Lamarche, Cody; Vishwas, Amit; Nikola, Thomas; Stacey, Gordon J.; Brisbin, Drew

2018-06-01

Galaxies have evolved significantly from the early Universe until today. Star formation rates, stellar and molecular gas masses, sizes and metal enrichment of galaxies have all changed significantly from early epochs until the present. Probing the physical conditions of galaxy at high redshift is vital to understanding this evolution. ZINGRS, the ZEUS 1 and 2 INvestigated Galaxy Reference Sample, provides a unique and powerful window for this work. The sample consists of more than ~30 galaxies from z ~ 1 - 4.5 for which the far-IR fine-structure lines (e.g. [CII] 158 micron, [NII] 122micron, [OIII] 88 micron) have been observed with the ZEUS-1 and 2 instruments. These lines are ideal for studying high-z systems since they require low energies for excitation, are typically optically thin, and are not susceptible to extinction from dust. ZINGRS is the largest collection of far-IR fine-structure line detections at high-z. Here we describe the sample, including extensive multifrequency supporting observations like CO & radio continuum, and summarize what we have learned so far.

Galaxy formation and physical bias

NASA Technical Reports Server (NTRS)

Cen, Renyue; Ostriker, Jeremiah P.

1992-01-01

We have supplemented our code, which computes the evolution of the physical state of a representative piece of the universe to include, not only the dynamics of dark matter (with a standard PM code), and the hydrodynamics of the gaseous component (including detailed collisional and radiative processes), but also galaxy formation on a heuristic but plausible basis. If, within a cell the gas is Jeans' unstable, collapsing, and cooling rapidly, it is transformed to galaxy subunits, which are then followed with a collisionless code. After grouping them into galaxies, we estimate the relative distributions of galaxies and dark matter and the relative velocities of galaxies and dark matter. In a large scale CDM run of 80/h Mpc size with 8 x 10 exp 6 cells and dark matter particles, we find that physical bias b is on the 8/h Mpc scale is about 1.6 and increases towards smaller scales, and that velocity bias is about 0.8 on the same scale. The comparable HDM simulation is highly biased with b = 2.7 on the 8/h Mpc scale. Implications of these results are discussed in the light of the COBE observations which provide an accurate normalization for the initial power spectrum. CDM can be ruled out on the basis of too large a predicted small scale velocity dispersion at greater than 95 percent confidence level.

Blue diffuse dwarf galaxies: a clearer picture

NASA Astrophysics Data System (ADS)

James, Bethan L.; Koposov, Sergey E.; Stark, Daniel P.; Belokurov, Vasily; Pettini, Max; Olszewski, Edward W.; McQuinn, Kristen B. W.

2017-03-01

The search for chemically unevolved galaxies remains prevalent in the nearby Universe, mostly because these systems provide excellent proxies for exploring in detail the physics of high-z systems. The most promising candidates are extremely metal-poor galaxies (XMPs), I.e. galaxies with <1/10 solar metallicity. However, due to the bright emission-line-based search criteria traditionally used to find XMPs, we may not be sampling the full XMP population. In 2014, we reoriented this search using only morphological properties and uncovered a population of ˜150 'blue diffuse dwarf (BDD) galaxies', and published a sub-sample of 12 BDD spectra. Here, we present optical spectroscopic observations of a larger sample of 51 BDDs, along with their Sloan Digital Sky Survey (SDSS) photometric properties. With our improved statistics, we use direct-method abundances to confirm that BDDs are chemically unevolved (7.43 < 12 + log(O/H) < 8.01), with ˜20 per cent of our sample classified as being XMP galaxies, and find that they are actively forming stars at rates of ˜1-33 × 10-2 M⊙ yr-1 in H II regions randomly embedded in a blue, low-surface-brightness continuum. Stellar masses are calculated from population synthesis models and estimated to be in the range log (M*/M⊙) ≃ 5-9. Unlike other low-metallicity star-forming galaxies, BDDs are in agreement with the mass-metallicity relation at low masses, suggesting that they are not accreting large amounts of pristine gas relative to their stellar mass. BDD galaxies appear to be a population of actively star-forming dwarf irregular (dIrr) galaxies which fall within the class of low-surface-brightness dIrr galaxies. Their ongoing star formation and irregular morphology make them excellent analogues for galaxies in the early Universe.

A New Orbit for the Eclipsing Binary V577 Oph

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jeffery, Elizabeth J.; Barnes, Thomas G. III; Montemayor, Thomas J.

Pulsating stars in eclipsing binary systems are unique objects for providing constraints on stellar models. To fully leverage the information available from the binary system, full orbital radial velocity curves must be obtained. We report 23 radial velocities for components of the eclipsing binary V577 Oph, whose primary star is a δ Sct variable. The velocities cover a nearly complete orbit and a time base of 20 years. We computed orbital elements for the binary and compared them to the ephemeris computed by Creevey et al. The comparison shows marginally different results. In particular, a change in the systemic velocitymore » by −2 km s{sup −1} is suggested by our results. We compare this systemic velocity difference to that expected due to reflex motion of the binary in response to the third body in the system. The systemic velocity difference is consistent with reflex motion, given our mass determination for the eclipsing binary and the orbital parameters determined by Volkov and Volkova for the three-body orbit. We see no evidence for the third body in our spectra, but we do see strong interstellar Na D lines that are consistent in strength with the direction and expected distance of V577 Oph.« less

Blueberry Galaxies: The Lowest Mass Young Starbursts

NASA Astrophysics Data System (ADS)

Yang, Huan; Malhotra, Sangeeta; Rhoads, James E.; Wang, Junxian

2017-09-01

Searching for extreme emission line galaxies allows us to find low-mass metal-poor galaxies that are good analogs of high redshift Lyα emitting galaxies. These low-mass extreme emission line galaxies are also potential Lyman-continuum leakers. Finding them at very low redshifts (z≲ 0.05) allows us to be sensitive to even lower stellar masses and metallicities. We report on a sample of extreme emission line galaxies at z≲ 0.05 (blueberry galaxies). We selected them from SDSS broadband images on the basis of their broadband colors and studied their properties with MMT spectroscopy. From the entire SDSS DR12 photometric catalog, we found 51 photometric candidates. We spectroscopically confirm 40 as blueberry galaxies. (An additional seven candidates are contaminants, and four remain without spectra.) These blueberries are dwarf starburst galaxies with very small sizes (<1 kpc) and very high ionization ([O III]/[O II] ˜ 10-60). They also have some of the lowest stellar masses ({log}(M/{M}⊙ )˜ 6.5{--}7.5) and lowest metallicities (7.1< 12+{log}({{O}}/{{H}})< 7.8) of starburst galaxies. Thus, they are small counterparts to green pea galaxies and high redshift Lyα emitting galaxies.

Association between ACTN3 R577X Polymorphism and Trunk Flexibility in 2 Different Cohorts.

PubMed

Kikuchi, Naoki; Zempo, Hirofumi; Fuku, Noriyuki; Murakami, Haruka; Sakamaki-Sunaga, Mikako; Okamoto, Takanobu; Nakazato, Koichi; Miyachi, Motohiko

2017-05-01

α-Actinin-3 (ACTN3) R577X polymorphism is associated with muscular strength and power. This study was performed to investigate the association between ACTN3 R577X polymorphisms and flexibility as another component of fitness in 2 cohorts. Cohort 1 consisted of 208 men and 568 women (ages 23-88), while Cohort 2 consisted of 529 men and 728 women (ages 23-87). All participants were recruited from the Tokyo metropolitan area and underwent a battery of tests to assess their grip strength and sit-and-reach flexibility. Genotyping results were analyzed for ACTN3 (rs1815739) polymorphism using the TaqMan approach. In Cohort 1, sit-and-reach in the RR genotype (35.3±0.7 cm) was significantly lower than those in the RX and XX genotypes (37.2±0.3 cm) even after adjusting for sex, age, and exercise habit as covariates (P<0.01). In Cohort 2, sit-and-reach tended to be lower in RR (38.1±0.6 cm) than in RX and XX (39.1±0.3 cm), but the differences were not significant (P=0.114). Analysis in pooled subjects indicated that RR was associated with significantly lower flexibility than RX and XX (P=0.009). The RR genotype of ACTN3 R577X in the general Japanese population showed lower flexibility compared to the RX and XX genotypes. © Georg Thieme Verlag KG Stuttgart · New York.

Galaxy And Mass Assembly (GAMA): the galaxy stellar mass function at z < 0.06

NASA Astrophysics Data System (ADS)

Baldry, I. K.; Driver, S. P.; Loveday, J.; Taylor, E. N.; Kelvin, L. S.; Liske, J.; Norberg, P.; Robotham, A. S. G.; Brough, S.; Hopkins, A. M.; Bamford, S. P.; Peacock, J. A.; Bland-Hawthorn, J.; Conselice, C. J.; Croom, S. M.; Jones, D. H.; Parkinson, H. R.; Popescu, C. C.; Prescott, M.; Sharp, R. G.; Tuffs, R. J.

2012-03-01

We determine the low-redshift field galaxy stellar mass function (GSMF) using an area of 143 deg2 from the first three years of the Galaxy And Mass Assembly (GAMA) survey. The magnitude limits of this redshift survey are r < 19.4 mag over two-thirds and 19.8 mag over one-third of the area. The GSMF is determined from a sample of 5210 galaxies using a density-corrected maximum volume method. This efficiently overcomes the issue of fluctuations in the number density versus redshift. With H0= 70 km s-1 Mpc-1, the GSMF is well described between 108 and 1011.5 M⊙ using a double Schechter function with ?, ?, α1=-0.35, ? and α2=-1.47. This result is more robust to uncertainties in the flow-model corrected redshifts than from the shallower Sloan Digital Sky Survey main sample (r < 17.8 mag). The upturn in the GSMF is also seen directly in the i-band and K-band galaxy luminosity functions. Accurately measuring the GSMF below 108 M⊙ is possible within the GAMA survey volume but as expected requires deeper imaging data to address the contribution from low surface-brightness galaxies.

Galaxy bias from galaxy–galaxy lensing in the DES science verification data

DOE PAGES

Prat, J.; Sánchez, C.; Miquel, R.; ...

2017-09-25

Here, we present a measurement of galaxy–galaxy lensing around a magnitude-limited (i AB < 22.5) sample of galaxies from the dark energy survey science verification (DES-SV) data. We split these lenses into three photometric-redshift bins from 0.2 to 0.8, and determine the product of the galaxy bias b and cross-correlation coefficient between the galaxy and dark matter overdensity fields r in each bin, using scales above 4 h –1 Mpc comoving, where we find the linear bias model to be valid given our current uncertainties. We compare our galaxy bias results from galaxy–galaxy lensing with those obtained from galaxy clusteringmore » and CMB lensing for the same sample of galaxies, and find our measurements to be in good agreement with those in Crocce et al., while, in the lowest redshift bin (z ~ 0.3), they show some tension with the findings in Giannantonio et al. We measure b · r to be 0.87 ± 0.11, 1.12 ± 0.16 and 1.24 ± 0.23, respectively, for the three redshift bins of width Δz = 0.2 in the range 0.2 < z < 0.8, defined with the photometric-redshift algorithm bpz. Using a different code to split the lens sample, tpz, leads to changes in the measured biases at the 10–20 per cent level, but it does not alter the main conclusion of this work: when comparing with Crocce et al. we do not find strong evidence for a cross-correlation parameter significantly below one in this galaxy sample, except possibly at the lowest redshift bin (z ~ 0.3), where we find r = 0.71 ± 0.11 when using tpz, and 0.83 ± 0.12 with bpz.« less

Galaxy bias from galaxy–galaxy lensing in the DES science verification data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prat, J.; Sánchez, C.; Miquel, R.

Here, we present a measurement of galaxy–galaxy lensing around a magnitude-limited (i AB < 22.5) sample of galaxies from the dark energy survey science verification (DES-SV) data. We split these lenses into three photometric-redshift bins from 0.2 to 0.8, and determine the product of the galaxy bias b and cross-correlation coefficient between the galaxy and dark matter overdensity fields r in each bin, using scales above 4 h –1 Mpc comoving, where we find the linear bias model to be valid given our current uncertainties. We compare our galaxy bias results from galaxy–galaxy lensing with those obtained from galaxy clusteringmore » and CMB lensing for the same sample of galaxies, and find our measurements to be in good agreement with those in Crocce et al., while, in the lowest redshift bin (z ~ 0.3), they show some tension with the findings in Giannantonio et al. We measure b · r to be 0.87 ± 0.11, 1.12 ± 0.16 and 1.24 ± 0.23, respectively, for the three redshift bins of width Δz = 0.2 in the range 0.2 < z < 0.8, defined with the photometric-redshift algorithm bpz. Using a different code to split the lens sample, tpz, leads to changes in the measured biases at the 10–20 per cent level, but it does not alter the main conclusion of this work: when comparing with Crocce et al. we do not find strong evidence for a cross-correlation parameter significantly below one in this galaxy sample, except possibly at the lowest redshift bin (z ~ 0.3), where we find r = 0.71 ± 0.11 when using tpz, and 0.83 ± 0.12 with bpz.« less

The Radial Distribution of Star Formation in Galaxies at z1 From The 3D-HST Survey

NASA Technical Reports Server (NTRS)

Nelson, Erica June; Dokkum, Pieter G. Van; Momcheva, Ivelina; Brammer, Gabriel; Lundgren, Britt; Skelton, Rosalind E.; Tease, Katherine Whitaker; Cunha, Elisabete Da; Schreiber, Natascha Forster; Franx, Marijn;

The MICE Grand Challenge lightcone simulation - II. Halo and galaxy catalogues

NASA Astrophysics Data System (ADS)

Crocce, M.; Castander, F. J.; Gaztañaga, E.; Fosalba, P.; Carretero, J.

2015-10-01

This is the second in a series of three papers in which we present an end-to-end simulation from the MICE collaboration, the MICE Grand Challenge (MICE-GC) run. The N-body contains about 70 billion dark-matter particles in a (3 h-1 Gpc)3 comoving volume spanning five orders of magnitude in dynamical range. Here, we introduce the halo and galaxy catalogues built upon it, both in a wide (5000 deg2) and deep (z < 1.4) lightcone and in several comoving snapshots. Haloes were resolved down to few 1011 h-1 M⊙. This allowed us to model galaxies down to absolute magnitude Mr < -18.9. We used a new hybrid halo occupation distribution and abundance matching technique for galaxy assignment. The catalogue includes the spectral energy distributions of all galaxies. We describe a variety of halo and galaxy clustering applications. We discuss how mass resolution effects can bias the large-scale two-pt clustering amplitude of poorly resolved haloes at the ≲5 per cent level, and their three-pt correlation function. We find a characteristic scale-dependent bias of ≲6 per cent across the BAO feature for haloes well above M⋆ ˜ 1012 h-1 M⊙ and for luminous red galaxy like galaxies. For haloes well below M⋆ the scale dependence at 100 h-1 Mpc is ≲2 per cent. Lastly, we discuss the validity of the large-scale Kaiser limit across redshift and departures from it towards non-linear scales. We make the current version of the lightcone halo and galaxy catalogue (MICECATv1.0) publicly available through a dedicated web portal to help develop and exploit the new generation of astronomical surveys.

The Weak Lensing Masses of Filaments between Luminous Red Galaxies

NASA Astrophysics Data System (ADS)

Epps, Seth D.; Hudson, Michael J.

2017-07-01

In the standard model of non-linear structure formation, a cosmic web of dark-matter-dominated filaments connects dark matter haloes. In this paper, we stack the weak lensing signal of an ensemble of filaments between groups and clusters of galaxies. Specifically, we detect the weak lensing signal, using CFHTLenS galaxy ellipticities, from stacked filaments between Sloan Digital Sky Survey (SDSS)-III/Baryon Oscillation Spectroscopic Survey luminous red galaxies (LRGs). As a control, we compare the physical LRG pairs with projected LRG pairs that are more widely separated in redshift space. We detect the excess filament mass density in the projected pairs at the 5σ level, finding a mass of (1.6 ± 0.3) × 1013 M⊙ for a stacked filament region 7.1 h-1 Mpc long and 2.5 h-1 Mpc wide. This filament signal is compared with a model based on the three-point galaxy-galaxy-convergence correlation function, as developed in Clampitt et al., yielding reasonable agreement.

SPT-CL J2040–4451: An SZ-selected galaxy cluster at x=1.478 with significant ongoing star formation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bayliss, M. B.; Ashby, M. L. N.; Ruel, J.

2014-09-18

SPT-CL J2040-4451-spectroscopically confirmed at z = 1.478-is the highest-redshift galaxy cluster yet discovered via the Sunyaev-Zel'dovich effect. SPT-CL J2040-4451 was a candidate galaxy cluster identified in the first 720 deg(2) of the South Pole Telescope Sunyaev-Zel'dovich (SPT-SZ) survey, and has been confirmed in follow-up imaging and spectroscopy. From multi-object spectroscopy with Magellan-I/Baade+ IMACS we measure spectroscopic redshifts for 15 cluster member galaxies, all of which have strong [O Pi]lambda lambda 3727 emission. SPT-CL J2040-4451 has an SZ-measured mass of M-500,(SZ) = 3.2 ± 0.8 x 10 14M(circle dot) h(-1) 70, corresponding to M-200,M- (SZ) = 5.8 ± 1.4 x 10more » 14M(circle dot) h(70-)(1.) The velocity dispersion measured entirely from blue star-forming members is sv = 1500 ± 520 km s -1. The prevalence of star-forming cluster members (galaxies with > 1.5M(circle dot) yr -1 implies that this massive, high-redshift cluster is experiencing a phase of active star formation, and supports recent results showing a marked increase in star formation occurring in galaxy clusters at z greater than or similar to 1.4. We also compute the probability of finding a cluster as rare as this in the SPT-SZ survey to be > 99%, indicating that its discovery is not in tension with the concordance Lambda CDM cosmological model.« less

Two views of the Andromeda Galaxy H-alpha and far infrared

NASA Technical Reports Server (NTRS)

Devereux, Nicholas A.; Price, Rob; Wells, Lisa A.; Duric, Neb

1994-01-01

A complete H-alpha image of the Andromeda Galaxy (M31) is presented allowing the first direct measurement of the total H-alpha luminosity which is (7.3 +/- 2.4) x 10(exp 6) solar luminosity. The H-alpha emission is associated with three morphologically distinct components; a large scale star-forming ring, approximately 1.65 deg in diameter, contributing 66% of the total H-alpha emission, a bright nucleus contributing 6% of the total H-alpha emission with the remaining 28% contributed by a previously unidentified component of extended and filamentary H-alpha emission interior to the star forming ring. The correspondence between the H-alpha image and the Infrared Astronomy Satellite (IRAS) far-infrared high resolution image is striking when both are convolved to a common resolution of 105 arcsec. The close correspondence between the far-infrared and H-alpha images suggests a common origin for the two emissions. The star-forming ring contributes 70% of the far-infrared luminosity of M31. Evidence that the ring emission is energized by high mass stars includes the fact that peaks in the far-infrared emission coincide identically with H II regions in the H-alpha image. In addition, the far-infrared to H-alpha luminosity ratio within the star-forming ring is similar to what one would expect for H II regions powered by stars of spectral types ranging between O9 and B0. The origin of the filamentary H-alpha and far-infrared luminosity interior to the star-forming ring is less clear, but it is almost certainly not produced by high mass stars.

On the Measurement of Elemental Abundance Ratios in Inner Galaxy H II Regions

NASA Technical Reports Server (NTRS)

Simpson, Janet P.; Rubin, Robert H.; Colgan, Sean W. J.; Erickson, Edwin F.; Haas, Michael R.

2004-01-01

Although abundance gradients in the Milky Way Galaxy certainly exist, details remain uncertain, particularly in the inner Galaxy, where stars and H II regions in the Galactic plane are obscured optically. In this paper we revisit two previously studied, inner Galaxy H II regions: G333.6-0.2 and W43. We observed three new positions in G333.6-0.2 with the Kuiper Airborne Observatory and reobserved the central position with the Infrared Space Observatory's Long Wavelength Spectrometer in far-infrared lines of S++, N++, N+, and O++. We also added the N+ lines at 122 and 205 microns to the suite of lines measured in W43 by Simpson et al.. The measured electron densities range from approx. 40 to over 4000 per cu cm in a single HII region, indicating that abundance analyses must consider density variations, since the critical densities of the observed lines range from 40 to 9000 per cu cm. We propose a method to handle density variations and make new estimates of the S/H and N/H abundance ratios. We find that our sulfur abundance estimates for G333.6-0.2 and W43 agree with the S/H abundance ratios expected for the gradient previously reported by Simpson et al., with the S/H values revised to be smaller owing to changes in collisional excitation cross sections. The estimated N/H, S/H, and N/S ratios are the most reliable because of their small corrections for unseen ionization states (< or approx. 10%). The estimated N/S ratios for the two sources are smaller than what would be calculated from the N/H and S/H ratios in our previous paper. If all low excitation H II regions had similar changes to their N/S ratios as a result of adding measurements of N+ to previous measurements of N++, there would be no or only a very small gradient in N/S. This is interesting because nitrogen is considered to be a secondary element and sulfur is a primary element in galactic chemical evolution calculations. We compute models of the two H II regions to estimate corrections for the other

A Spectroscopic Survey of Lensed Dwarf Galaxies at 1

NASA Astrophysics Data System (ADS)

Alavi, Anahita; Siana, Brian; gburek, Timothy; Richard, Johan; Teplitz, Harry; Rafelski, Marc; Stark, Daniel P.; Anahita Alavi

2018-01-01

High-redshift dwarf galaxies (M<109 M⊙) are one of the primary targets of the James Web Space Telescope. Recent studies have suggested that these galaxies are different than their bright counterparts, as they follow a divergent evolutionary history of star formation. In our previous study, utilizing the magnification from massive clusters of galaxies (Hubble Frontier Fields), we found a large sample of dwarf star-forming galaxies at the peak epoch of star formation (1galaxies, we have conducted a spectroscopic survey of these lensed faint galaxies using the Multi-Object Near-IR Spectrograph (MOSFIRE) at the Keck observatory. In this talk, I will present their nebular dust attenuation measurements using the ratio of Balmer lines (i.e., Balmer decrement) and compare with their stellar dust attenuation (i.e., from UV spectral slopes). I will also show that these faint galaxies follow a steep dust extinction curve (i.e., SMC like).

Broadband spectral study of the jet-disc emission in the radio-loud narrow-line Seyfert 1 galaxy 1H 0323+342

NASA Astrophysics Data System (ADS)

Ghosh, Ritesh; Dewangan, Gulab C.; Mallick, Labani; Raychaudhuri, Biplab

2018-06-01

We present a broadband spectral study of the radio-loud narrow-line Seyfert 1 galaxy 1H 0323+342 based on multi-epoch observations performed with NuSTAR on 2014 March 15, and two simultaneous observations performed with Suzaku and Swift on 2009 July 26 and 2013 March 1. We found the presence of a strong soft X-ray excess emission, a broad but weak Fe line and hard X-ray excess emission. We used the blurred reflection (relxill) and the intrinsic disc Comptonization (optxagnf), two physically motivated models, to describe the broadband spectra and to disentangle the disk/corona and jet emission. The relxill model is mainly constrained by the strong soft X-ray excess although the model failed to predict this excess when fitted above 3{keV} and extrapolated to lower energies. The joint spectral analysis of the three datasets above 3{keV} with this model resulted in a high black hole spin (a > 0.9) and moderate reflection fraction R ˜ 0.5. The optxagnf model fitted to the two simultaneous datasets resulted in an excess emission in the UV band. The simultaneous UV-to-hard X-ray spectra of 1H 0323+342 are best described by a model consisting of a primary X-ray power-law continuum with Γ ˜ 1.8, a blurred reflection component with R ˜ 0.5, Comptonised disk emission as the soft X-ray excess, optical/UV emission from a standard accretion disk around a black hole of mass ˜107M⊙ and a steep power law (Γ ˜ 3 - 3.5) component, most likely the jet emission in the UV band. The fractional RMS variability spectra suggest that both the soft excess and the powerlaw component are variable in nature.

H I Structure and Topology of the Galaxy Revealed by the I-GALFA H I 21-cm Line Survey

NASA Astrophysics Data System (ADS)

Koo, Bon-Chul; Park, G.; Cho, W.; Gibson, S. J.; Kang, J.; Douglas, K. A.; Peek, J. E. G.; Korpela, E. J.; Heiles, C. E.

2011-05-01

The I-GALFA survey mapping all the H I in the inner Galactic disk visible to the Arecibo 305m telescope within 10 degrees of the Galactic plane (longitudes of 32 to 77 degrees at b = 0) completed observations in 2009 September and will soon be made publicly available. The high (3.4 arcmin) resolution and tremendous sensitivity of the survey offer a great opportunity to observe the fine details of H I both in the inner and in the far outer Galaxy. The reduced HI column density maps show that the HI structure is highly filamentary and clumpy, pervaded by shell-like structures, vertical filaments, and small clumps. By inspecting individual maps, we have found 36 shell candidates of angular sizes ranging from 0.4 to 12 degrees, half of which appear to be expanding. In order to characterize the filamentary/clumpy morphology of the HI structure, we have carried out statistical analyses of selected areas representing the spiral arms in the inner and outer Galaxy. Genus statistics that can distinguish the ``meatball'' and ``swiss-cheese'' topologies show that the HI topology is clump-like in most regions. The two-dimensional Fourier analysis further shows the HI structures are filamentary and mainly parallel to the plane in the outer Galaxy. We also examine the level-crossing statistics, the results of which are described in detail in an accompanying poster by Park et al.

40 CFR 180.577 - Bispyribac-sodium; tolerances for residues.

Code of Federal Regulations, 2010 CFR

2010-07-01

... § 180.577 Bispyribac-sodium; tolerances for residues. (a) General. Tolerances are established for residues of bispyribac-sodium, sodium 2,6-bis[(4,6-dimethoxy-pyrimidin-2-yl)oxy]benzoate, in or on the... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Bispyribac-sodium; tolerances for...

Cold Dark Matter Cosmogony with Hydrodynamics and Galaxy Formation: Galaxy Properties at Redshift Zero

NASA Astrophysics Data System (ADS)

Cen, Renyue; Ostriker, Jeremiah P.

1993-11-01

We have supplemented our code, which computes the evolution of the physical state of a representative piece of the universe, to include not only the dynamics of dark matter (with a standard PM code) and the hydrodynamics of the gaseous component (including detailed collisional and radiative processes), but also galaxy formation on a heuristic but plausible basis. If, within a cell, the gas is Jeans-unstable, collapsing and cooling rapidly, it is transformed to galaxy subunits, which are then followed with a collisionless code. We study two representative boxes with sizes L = (80, 8) h-1 Mpc, in both cases utilizing a mesh of 2003 cells containing 2003 dark matter particles and having nominal resolutions of (400, 40) h-1 kpc, respectively, with true resolution approximately 2.5 times worse. We adopt the standard cold dark matter (CDM) perturbation spectrum with an amplitude of σ8 ≡ = (δM/M)rms,8 = 0.77, a compromise between the COBE normalization σ8 = 1.05 and that indicated by the small-scale velocity dispersion (perhaps σ8 = 0.45). We find a mass function which is similar to that observed. There is a strong correlation between galactic age and environment. Identifying the oldest fraction with elliptical and 50 galaxies, we find a density morphology relation of the same type as is observed as well as a correlation between gas mass/total mass ratio and morphology that is similar to observations. In addition, we find that low-mass galaxies contain relatively more dark matter than giants. We present analytic fits to our derived results for "bias," the dependence of ρgal/ <ρgal> on ρtot/<ρtot>. Spatial structures resemble quantitatively those seen in redshift surveys, with galaxies concentrated in clusters and on filaments (or sheets) which surround quite empty voids. The void probability statistics indicate that this model is consistent with magnitude-limited real data. The small-scale velocity field is too large compared with the observed velocity

What made discy galaxies giant?

NASA Astrophysics Data System (ADS)

Saburova, A. S.

2018-01-01

I studied giant discy galaxies with optical radii more than 30 kpc. The comparison of these systems with discy galaxies of moderate sizes revealed that they tend to have higher rotation velocities, B-band luminosities, H I masses and dark-to-luminous mass ratios. The giant discs follow the trend log (M_{H I})(R_{25}) found for normal sized galaxies. It indicates the absence of the peculiarities of evolution of star formation in these galaxies. The H I mass-to-luminosity ratio of giant galaxies appears not to differ from that of normal-sized galaxies, giving evidence in favour of similar star formation efficiency. I also found that the bars and rings occur more frequently among giant discs. I performed mass modelling of the subsample of 18 giant galaxies with available rotation curves and surface photometry data and constructed χ2 maps for the parameters of their dark matter haloes. These estimates indicate that giant discs tend to be formed in larger more massive and rarified dark haloes in comparison to moderate-sized galaxies. However, giant galaxies do not deviate significantly from the relations between the optical sizes and dark halo parameters for moderate-sized galaxies. These findings can rule out the catastrophic scenario of the formation of at least most of giant discs, since they follow the same relations as normal discy galaxies. The giant sizes of the discs can be due to the high radial scale of the dark matter haloes in which they were formed.

Diffuse Optical Light in Galaxy Clusters. I. Abell 3888

NASA Astrophysics Data System (ADS)

Krick, J. E.; Bernstein, R. A.; Pimbblet, K. A.

2006-01-01

We are undertaking a program to measure the characteristics of the intracluster light (ICL; total flux, profile, color, and substructure) in a sample of 10 galaxy clusters with a range of cluster mass, morphology, and redshift. We present here the methods and results for the first cluster in that sample, A3888. We have identified an ICL component in A3888 in V and r that contains 13%+/-5% of the total cluster light and extends to 700 h-170 kpc (~0.3r200) from the center of the cluster. The ICL color in our smallest radial bin is V-r=0.3+/-0.1, similar to the central cluster elliptical galaxies. The ICL is redder than the galaxies at 400 h-170 kpch-170 kpc, although the uncertainty in any one radial bin is high. Based on a comparison of V-r color with simple stellar models, the ICL contains a component that formed more than 7 Gyr ago (at z>1) with a high-metallicity (1.0 Zsolar1). The profile of the ICL can be roughly fitted by a shallow exponential in the outer regions and a steeper exponential in the central region. We also find a concentration of diffuse light around a small group of galaxies 1.4 h-170 Mpc from the center of the cluster. In addition, we find three low surface brightness features near the cluster center that are blue (V-r=0.0) and contain a total flux of 0.1M*. Based on these observations and X-ray and galaxy morphology, we suggest that this cluster is entering a phase of significant merging of galaxy groups in the core, whereupon we expect the ICL fraction to grow significantly with the formation of a cD galaxy, as well as the infall of groups.

Early Science with the Large Millimeter Telescope: discovery of the 12CO(1-0) emission line in the ring galaxy VIIZw466

NASA Astrophysics Data System (ADS)

Wong, O. Ivy; Vega, O.; Sánchez-Argüelles, D.; Narayanan, G.; Wall, W. F.; Zwaan, M. A.; Rosa González, D.; Zeballos, M.; Bekki, K.; Mayya, Y. D.; Montaña, A.; Chung, A.

2017-04-01

We report an early science discovery of the 12CO(1-0) emission line in the collisional ring galaxy VII Zw466, using the Redshift Search Receiver instrument on the Large Millimeter Telescope Alfonso Serrano. The apparent molecular-to-atomic gas ratio either places the interstellar medium (ISM) of VII Zw466 in the H I-dominated regime or implies a large quantity of CO-dark molecular gas, given its high star formation rate. The molecular gas densities and star formation rate densities of VII Zw466 are consistent with the standard Kennicutt-Schmidt star formation law even though we find this galaxy to be H2-deficient. The choice of CO-to-H2 conversion factors cannot explain the apparent H2 deficiency in its entirety. Hence, we find that the collisional ring galaxy, VII Zw466, is either largely deficient in both H2 and H I or contains a large mass of CO-dark gas. A low molecular gas fraction could be due to the enhancement of feedback processes from previous episodes of star formation as a result of the star-forming ISM being confined to the ring. We conclude that collisional ring galaxy formation is an extreme form of galaxy interaction that triggers a strong galactic-wide burst of star formation that may provide immediate negative feedback towards subsequent episodes of star formation - resulting in a short-lived star formation history or, at least, the appearance of a molecular gas deficit.

Study of GRBs Hosts Galaxies Vicinity Properties

NASA Astrophysics Data System (ADS)

Bernal, S.; Vasquez, N.; Hoyle, F.

2017-07-01

The study of GRBs host galaxies and its vicinity could provide constrains on the progenitor and an opportunity to use these violent explosions to characterize the nature of the highredshift universe. Studies of GRB host galaxies reveal a population of starforming galaxies with great diversity, spanning a wide range of masses, star formation rate, and redshifts. In order to study the galactic ambient of GRBs we used the S. Savaglio catalog from 2015 where 245 GRBs are listed with RA-Dec position and z. We choose 22 GRBs Hosts galaxies from Savaglio catalog and SDSS DR12, with z range 01, and a total of 1703 galaxies, in a local vicinity of 10 h-1 Mpc radius to determine some photometric and population characteristics. We calculate the volumetric density populatation of glalaxies around the GRB Hosts within a volume of an sphere whit radius of 10 h-1 Mpc and find a low density compared with a typical group of galaxies. In order to know the galaxies stellar formation state, in regions where GRBs are formed, we made an analysis of color index using SDSS data of μ [λ 3543], r[λ 6231] and calculate the indexes μ-r. We find a value μ-r=2.63, it means that the galactic ambient of GRBs Host regions are statistically redder than void and wall regions on a indirect way (Voids:μ-r=2.043; Walls:μ-r=2.162). Futhermore, we used a inverse concentration index analysis, ICI=R50/R90 and find that galaxies in GRBs Hosts vicinity are also of slightly early type than void and wall galaxies. With this work we provide characteristics on the regions for future works related with highredsift universe that using the GRBs.

1.25-mm observations of luminous infrared galaxies

NASA Technical Reports Server (NTRS)

Carico, David P.; Keene, Jocelyn; Soifer, B. T.; Neugebauer, G.

1992-01-01

Measurements at a wavelength of 1.25 mm have been obtained for 17 IRAS galaxies selected on the basis of high far-infrared luminosity. These measurements are used to estimate the lower and upper limits to the mass of cold dust in infrared galaxies. As a lower limit on dust mass, all of the galaxies can be successfully modeled without invoking any dust colder than the dust responsible for the 60 and 100 micron emission that was detected by IRAS. As an upper limit, it is possible that the dust mass in a number of the galaxies may actually be dominated by cold dust. This large difference between the lower and upper limits is due primarily to uncertainty in the long-wavelength absorption efficiency of the astrophysical dust grains.

Chemical enrichment in isolated barred spiral galaxies.

NASA Astrophysics Data System (ADS)

Martel, Hugo; Carles, Christian; Robichaud, Fidéle; Ellison, Sara L.; Williamson, David J.

2018-04-01

To investigate the role of bars in the chemical evolution of isolated disc galaxies, we performed a series of 39 gas dynamical simulations of isolated barred and unbarred galaxies with various masses, initial gas fractions, and AGN feedback models. The presence of a bar drives a substantial amount of gas toward the central region of the galaxy. In the most massive galaxies, this results in a violent starburst, followed by a drop in star formation resulting from gas exhaustion. The time delay between Type Ia and Type II supernovae explosions means that barred galaxies experience a rapid increase in [O/H] in the central region, and a much more gradual increase in [Fe/H]. In unbarred galaxies, star formation proceeds at a slow and steady rate, and oxygen and iron are produced at steady rates which are similar except for a time offset. Comparing the abundance ratios in barred and unbarred galaxies with the same central stellar mass M*, we find in barred galaxies an enhancement of 0.07 dex in [O/H], 0.05 dex in [Fe/H], and 0.05 dex in [O/Fe]. The [O/H] enhancement is in excellent agreement with observations from the SDSS. The initial gas fraction has very little effect on the abundance ratios in barred and unbarred galaxies, unless the galaxies experience a starburst. We considered AGN-host galaxies located near the bottom of the AGN regime, M* ≳ 3 × 1010M⊙, where AGN feedback dominates over supernovae feedback. We found that the impact of AGN feedback on the central abundances is marginal.

An Hα Imaging Survey of the Low-surface-brightness Galaxies Selected from the Fall Sky Region of the 40% ALFALFA H I Survey

NASA Astrophysics Data System (ADS)

Lei, Feng-Jie; Wu, Hong; Du, Wei; Zhu, Yi-Nan; Lam, Man-I.; Zhou, Zhi-Min; He, Min; Jin, Jun-Jie; Cao, Tian-Wen; Zhao, Pin-Song; Yang, Fan; Wu, Chao-Jian; Li, Hong-Bin; Ren, Juan-Juan

2018-03-01

We present the observed Hα flux and derived star formation rates (SFRs) for a fall sample of low-surface-brightness galaxies (LSBGs). The sample is selected from the fall sky region of the 40% ALFALFA H I Survey–SDSS DR7 photometric data, and all the Hα images were obtained using the 2.16 m telescope, operated by the National Astronomy Observatories, Chinese Academy of Sciences. A total of 111 LSBGs were observed and Hα flux was measured in 92 of them. Though almost all the LSBGs in our sample are H I-rich, their SFRs, derived from the extinction and filter-transmission-corrected Hα flux, are less than 1 M ⊙ yr‑1. LSBGs and star-forming galaxies have similar H I surface densities, but LSBGs have much lower SFRs and SFR surface densities than star-forming galaxies. Our results show that LSBGs deviate from the Kennicutt–Schmidt law significantly, which indicates that they have low star formation efficiency. The SFRs of LSBGs are close to average SFRs in Hubble time and support previous arguments that most of the LSBGs are stable systems and they tend to seldom contain strong interactions or major mergers in their star formation histories.

A violent interaction between the dwarf galaxy UGC 7636 and the giant elliptical galaxy NGC 4472

NASA Technical Reports Server (NTRS)

Mcnamara, Brian R.; Sancisi, Renzo; Henning, Patricia A.; Junor, William

1994-01-01

We present new U, B, R, and H I imagery of the Virgo Cluster giant elliptical galaxy NGC 4472 and its interacting dwarf companion galaxy UGC 7636. Using a composite image reconstruction technique, we show that a trail of debris approx. 5 arcmin in length and approx. 1 arcmin in width (30x6 kpc for a Virgo cluster distance of 20 Mpc) is projected northward from the dwarf galaxy. A cloud of H I is projected along the northwest edge of the debris between the dwarf and gE. The dwarf's nuclear morphology is irregular and bow-shaped on what appears to be its leading edge. Apart from a number of isolated blue regions, most of of the trailing debris is similar in color to the dwarf's nucleus. Only a modest enhancement of star formation appears to have been induced by the interaction. Although separated by 15 kpc, the H I and stellar morphologies are remarkably similar. The stars and H I appear to have been tidally distorted in situ, prior to the cloud's removal by ram pressure. If the H I has maintained its shape by magnetic support, a magnetic field strength an order of magnitude larger than the galaxy's is required. Ram pressure deceleration due to the cloud's motion through NGC 4472's x-ray-emitting interstellar medium shold be sufficient for the cloud to become gravitationally bound to NGC 4472. The H I cloud is not self-gravitating and may fragment and be destroyed in the interaction. UGC 7636 will probably be disrupted by NGC 4472's strong tidal forces; the stellar debris will disperse into the Virgo cluster or become bound to NGC 4472's halo on eccentric orbits. The debris captured in the collision will have a negligible impact on NGC 4472's stellar and gaseous content. On the other hand, if similar interactions are common in giant elliptical galaxies, they could alter or deplete surrounding dwarf galaxy populations, fuel bursts of nuclear activity, and perhaps provide a source of magnetic energy to their interstellar media.

High-resolution Imaging of PHIBSS z ˜ 2 Main-sequence Galaxies in CO J = 1 → 0

NASA Astrophysics Data System (ADS)

Bolatto, A. D.; Warren, S. R.; Leroy, A. K.; Tacconi, L. J.; Bouché, N.; Förster Schreiber, N. M.; Genzel, R.; Cooper, M. C.; Fisher, D. B.; Combes, F.; García-Burillo, S.; Burkert, A.; Bournaud, F.; Weiss, A.; Saintonge, A.; Wuyts, S.; Sternberg, A.

2015-08-01

We present Karl Jansky Very Large Array observations of the CO J=1-0 transition in a sample of four z˜ 2 main-sequence galaxies. These galaxies are in the blue sequence of star-forming galaxies at their redshift, and are part of the IRAM Plateau de Bure HIgh-z Blue Sequence Survey which imaged them in CO J=3-2. Two galaxies are imaged here at high signal-to-noise, allowing determinations of their disk sizes, line profiles, molecular surface densities, and excitation. Using these and published measurements, we show that the CO and optical disks have similar sizes in main-sequence galaxies, and in the galaxy where we can compare CO J=1-0 and J=3-2 sizes we find these are also very similar. Assuming a Galactic CO-to-H2 conversion, we measure surface densities of {{{Σ }}}{mol}˜ 1200 {M}⊙ pc-2 in projection and estimate {{{Σ }}}{mol}˜ 500-900 {M}⊙ pc-2 deprojected. Finally, our data yields velocity-integrated Rayleigh-Jeans brightness temperature line ratios r31 that are approximately at unity. In addition to the similar disk sizes, the very similar line profiles in J=1-0 and J=3-2 indicate that both transitions sample the same kinematics, implying that their emission is coextensive. We conclude that in these two main-sequence galaxies there is no evidence for significant excitation gradients or a large molecular reservoir that is diffuse or cold and not involved in active star formation. We suggest that r31 in very actively star-forming galaxies is likely an indicator of how well-mixed the star formation activity and the molecular reservoir are.

Detection of a Substantial Molecular Gas Reservoir in a Brightest Cluster Galaxy at z = 1.7

NASA Astrophysics Data System (ADS)

Webb, Tracy M. A.; Lowenthal, James; Yun, Min; Noble, Allison G.; Muzzin, Adam; Wilson, Gillian; Yee, H. K. C.; Cybulski, Ryan; Aretxaga, I.; Hughes, D. H.

2017-08-01

We report the detection of CO(2-1) emission coincident with the brightest cluster galaxy (BCG) of the high-redshift galaxy cluster SpARCS1049+56, with the Redshift Search Receiver (RSR) on the Large Millimeter Telescope (LMT). We confirm a spectroscopic redshift for the gas of z = 1.7091 ± 0.0004, which is consistent with the systemic redshift of the cluster galaxies of z = 1.709. The line is well fit by a single-component Gaussian with an RSR-resolution-corrected FWHM of 569 ± 63 km s-1. We see no evidence for multiple velocity components in the gas, as might be expected from the multiple image components seen in near-infrared imaging with the Hubble Space Telescope. We measure the integrated flux of the line to be 3.6 ± 0.3 Jy km s-1, and using {α }{CO} = 0.8 M ⊙ (K km s-1 pc2)-1, we estimate a total molecular gas mass of 1.1 ± 0.1 × 1011 M ⊙ and a M H2/M ⋆ ˜ 0.4. This is the largest gas reservoir detected in a BCG above z > 1 to date. Given the infrared-estimated star formation rate of 860 ± 130 M ⊙ yr-1, this corresponds to a gas depletion timescale of ˜0.1 Gyr. We discuss several possible mechanisms for depositing such a large gas reservoir to the cluster center—e.g., a cooling flow, a major galaxy-galaxy merger, or the stripping of gas from several galaxies—but conclude that these LMT data are not sufficient to differentiate between them.

The host galaxy of the γ-ray-emitting narrow-line Seyfert 1 galaxy PKS 1502+036

NASA Astrophysics Data System (ADS)

D'Ammando, F.; Acosta-Pulido, J. A.; Capetti, A.; Baldi, R. D.; Orienti, M.; Raiteri, C. M.; Ramos Almeida, C.

2018-07-01

The detection of γ-ray emission from narrow-line Seyfert 1 galaxies (NLSy1) has challenged the idea that large black hole (BH) masses (≥108 M⊙) are needed to launch relativistic jets. We present near-infrared imaging data of the γ-ray-emitting NLSy1 PKS 1502+036 obtained with the Very Large Telescope. Its surface brightness profile, extending to ˜20 kpc, is well described by the combination of a nuclear component and a bulge with a Sérsic index n = 3.5, which is indicative of an elliptical galaxy. A circumnuclear structure observed near PKS 1502+036 may be the result of galaxy interactions. A BH mass of ˜7 × 108 M⊙ has been estimated by the bulge luminosity. The presence of an additional faint disc component cannot be ruled out with the present data, but this would reduce the BH mass estimate by only ˜30 per cent. These results, together with analogous findings obtained for FBQS J1644+2619, indicate that the relativistic jets in γ-ray-emitting NLSy1 are likely produced by massive black holes at the centre of elliptical galaxies.

The host galaxy of the γ-ray-emitting narrow-line Seyfert 1 galaxy PKS 1502+036

NASA Astrophysics Data System (ADS)

D'Ammando, F.; Acosta-Pulido, J. A.; Capetti, A.; Baldi, R. D.; Orienti, M.; Raiteri, C. M.; Ramos Almeida, C.

2018-04-01

The detection of γ-ray emission from narrow-line Seyfert 1 galaxies (NLSy1) has challenged the idea that large black hole (BH) masses (≥108 M⊙) are needed to launch relativistic jets. We present near-infrared imaging data of the γ-ray-emitting NLSy1 PKS 1502+036 obtained with the Very Large Telescope. Its surface brightness profile, extending to ˜ 20 kpc, is well described by the combination of a nuclear component and a bulge with a Sérsic index n = 3.5, which is indicative of an elliptical galaxy. A circumnuclear structure observed near PKS 1502+036 may be the result of galaxy interactions. A BH mass of ˜7 × 108 M⊙ has been estimated by the bulge luminosity. The presence of an additional faint disc component cannot be ruled out with the present data, but this would reduce the BH mass estimate by only ˜ 30%. These results, together with analogous findings obtained for FBQS J1644+2619, indicate that the relativistic jets in γ-ray-emitting NLSy1 are likely produced by massive black holes at the center of elliptical galaxies.

Large-Scale Clustering of Galaxies in the CFA Survey

NASA Astrophysics Data System (ADS)

Park, Changbom

1992-03-01

The power spectrum of the galaxy distribution is accuarately measured up to wavelengths over 100h-1 Mpc from the CfA 1 and 2 catalogs. We find that our results agree with power spectra calculated by others from smaller samples of optical, radio and infrared galaxies. The power spectrum of an open CDM model (Omega h = 0.2 and delta8 = 1; see below for definitions) best approximates the observed power spectrum. The power spectrum of the standard CDM model(Omega h = 0.5 and delta8 = 1) is inconsistent with the observed one at the 99% confidence level. Our best estimation of the corresponding correlation function in real space is Xi(r) = (r/6.2h-1 Mpc)^-1.8 for r < 20h-1 Mpc.

Voids and constraints on nonlinear clustering of galaxies

NASA Technical Reports Server (NTRS)

Vogeley, Michael S.; Geller, Margaret J.; Park, Changbom; Huchra, John P.

1994-01-01

Void statistics of the galaxy distribution in the Center for Astrophysics Redshift Survey provide strong constraints on galaxy clustering in the nonlinear regime, i.e., on scales R equal to or less than 10/h Mpc. Computation of high-order moments of the galaxy distribution requires a sample that (1) densely traces the large-scale structure and (2) covers sufficient volume to obtain good statistics. The CfA redshift survey densely samples structure on scales equal to or less than 10/h Mpc and has sufficient depth and angular coverage to approach a fair sample on these scales. In the nonlinear regime, the void probability function (VPF) for CfA samples exhibits apparent agreement with hierarchical scaling (such scaling implies that the N-point correlation functions for N greater than 2 depend only on pairwise products of the two-point function xi(r)) However, simulations of cosmological models show that this scaling in redshift space does not necessarily imply such scaling in real space, even in the nonlinear regime; peculiar velocities cause distortions which can yield erroneous agreement with hierarchical scaling. The underdensity probability measures the frequency of 'voids' with density rho less than 0.2 -/rho. This statistic reveals a paucity of very bright galaxies (L greater than L asterisk) in the 'voids.' Underdensities are equal to or greater than 2 sigma more frequent in bright galaxy samples than in samples that include fainter galaxies. Comparison of void statistics of CfA samples with simulations of a range of cosmological models favors models with Gaussian primordial fluctuations and Cold Dark Matter (CDM)-like initial power spectra. Biased models tend to produce voids that are too empty. We also compare these data with three specific models of the Cold Dark Matter cosmogony: an unbiased, open universe CDM model (omega = 0.4, h = 0.5) provides a good match to the VPF of the CfA samples. Biasing of the galaxy distribution in the 'standard' CDM model

The Splashback Feature around DES Galaxy Clusters: Galaxy Density and Weak Lensing Profiles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, Chihway; et al.

Splashback refers to the process of matter that is accreting onto a dark matter halo reaching its first orbital apocenter and turning around in its orbit. The cluster-centric radius at which this process occurs, r_sp, defines a halo boundary that is connected to the dynamics of the cluster, in contrast with other common halo boundary definitions such as R_200. A rapid decline in the matter density profile of the halo is expected near r_sp. We measure the galaxy number density and weak lensing mass profiles around RedMapper galaxy clusters in the first year Dark Energy Survey (DES) data. For amore » cluster sample with mean mass ~2.5 x 10^14 solar masses, we find strong evidence of a splashback-like steepening of the galaxy density profile and measure r_sp=1.16 +/- 0.08 Mpc/h, consistent with earlier SDSS measurements of More et al. (2016) and Baxter et al. (2017). Moreover, our weak lensing measurement demonstrates for the first time the existence of a splashback-like steepening of the matter profile of galaxy clusters. We measure r_sp=1.28 +/- 0.18 Mpc/h from the weak lensing data, in good agreement with our galaxy density measurements. Applying our analysis to different cluster and galaxy samples, we find that consistent with LambdaCDM simulations, r_sp scales with R_200m and does not evolve with redshift over the redshift range of 0.3--0.6. We also find that potential systematic effects associated with the RedMapper algorithm may impact the location of r_sp, in particular the choice of scale used to estimate cluster richness. We discuss progress needed to understand the systematic uncertainties and fully exploit forthcoming data from DES and future surveys, emphasizing the importance of more realistic mock catalogs and independent cluster samples.« less

1.75 h {sup -1} kpc SEPARATION DUAL ACTIVE GALACTIC NUCLEI AT z = 0.36 IN THE COSMOS FIELD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Comerford, Julia M.; Davis, Marc; Griffith, Roger L.

2009-09-01

We present strong evidence for dual active galactic nuclei (AGNs) in the z = 0.36 galaxy COSMOS J100043.15+020637.2. COSMOS Hubble Space Telescope (HST) imaging of the galaxy shows a tidal tail, indicating that the galaxy recently underwent a merger, as well as two bright point sources near the galaxy's center. The luminosities of these sources (derived from the HST image) and their emission line flux ratios (derived from Keck/DEIMOS slit spectroscopy) suggest that both are AGNs and not star-forming regions or supernovae. Observations from zCOSMOS, the Sloan Digital Sky Survey, XMM-Newton, Spitzer, and the Very Large Array fortify the evidencemore » for AGN activity. With HST imaging we measure a projected spatial offset between the two AGNs of 1.75 {+-} 0.03 h {sup -1} kpc, and with DEIMOS we measure a 150 {+-} 40 km s{sup -1} line-of-sight velocity offset between the two AGNs. Combined, these observations provide substantial evidence that COSMOS J100043.15+020637.2 is a merger-remnant galaxy with dual AGNs.« less

The Greater Impact of Mergers on the Growth of Massive Galaxies: Implications for Mass Assembly and Evolution since z sime 1

NASA Astrophysics Data System (ADS)

Bundy, Kevin; Fukugita, Masataka; Ellis, Richard S.; Targett, Thomas A.; Belli, Sirio; Kodama, Tadayuki

2009-06-01

Using deep infrared observations conducted with the MOIRCS imager on the Subaru Telescope in the northern GOODS field combined with public surveys in GOODS-S, we investigate the dependence on stellar mass, M *, and galaxy type of the close pair fraction (5 h -1 kpc < r sep < 20 h -1 kpc) and implied merger rate. In terms of combined depth and survey area, our publicly available mass-limited sample represents a significant improvement over earlier infrared surveys used for this purpose. In common with some recent studies, we find that the fraction of paired systems that could result in major mergers is low (~4%) and does not increase significantly with redshift to z ≈ 1.2, with vprop(1 + z)1.6±1.6. Our key finding is that massive galaxies with M *>1011 M sun are more likely to host merging companions than less massive systems (M * ~ 1010 M sun). We find evidence for a higher pair fraction for red, spheroidal hosts compared to blue, late-type systems, in line with expectations based on clustering at small scales. The so-called "dry" mergers between early-type galaxies devoid of star formation (SF) represent nearly 50% of close pairs with M *>3 × 1010 M sun at z ~ 0.5, but less than 30% at z ~ 1. This result can be explained by the increasing abundance of red, early-type galaxies at these masses. We compare the volumetric merger rate of galaxies with different masses to mass-dependent trends in galaxy evolution. Our results reaffirm the conclusion of Bundy et al. that major mergers do not fully account for the formation of spheroidal galaxies since z ~ 1. In terms of mass assembly, major mergers contribute little to galaxy growth below M * ~ 3 × 1010 M sun but play a more significant role among galaxies with M * gsim 1011 M sun ~ 30% of which have undergone mostly dry mergers over the observed redshift range. Overall, the relatively rapid and recent coalescence of high-mass galaxies mirrors the expected hierarchical growth of halos and is consistent with recent

Resolved H I Observations of Local Analogs to z ∼ 1 Luminous Compact Blue Galaxies: Evidence for Rotation-supported Disks

NASA Astrophysics Data System (ADS)

Rabidoux, Katie; Pisano, D. J.; Garland, C. A.; Guzmán, Rafael; Castander, Francisco J.; Wolfe, Spencer A.

2018-01-01

While bright, blue, compact galaxies are common at z∼ 1, they are relatively rare in the local universe, and their evolutionary paths are uncertain. We have obtained resolved H I observations of nine z∼ 0 luminous compact blue galaxies (LCBGs) using the Giant Metrewave Radio Telescope and Very Large Array in order to measure their kinematic and dynamical properties and better constrain their evolutionary possibilities. We find that the LCBGs in our sample are rotating galaxies that tend to have nearby companions, relatively high central velocity dispersions, and can have disturbed velocity fields. We calculate rotation velocities for each galaxy by measuring half of the velocity gradient along their major axes and correcting for inclination using axis ratios derived from SDSS images of each galaxy. We compare our measurements to those previously made with single dishes and find that single-dish measurements tend to overestimate LCBGs’ rotation velocities and H I masses. We also compare the ratio of LCBGs’ rotation velocities and velocity dispersions to those of other types of galaxies and find that LCBGs are strongly rotationally supported at large radii, similar to other disk galaxies, though within their half-light radii the {V}{rot}/σ values of their H I are comparable to stellar {V}{rot}/σ values of dwarf elliptical galaxies. We find that LCBGs’ disks on average are gravitationally stable, though conditions may be conducive to local gravitational instabilities at the largest radii. Such instabilities could lead to the formation of star-forming gas clumps in the disk, resulting eventually in a small central bulge or bar.

THE EXTREME SMALL SCALES: DO SATELLITE GALAXIES TRACE DARK MATTER?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Watson, Douglas F.; Berlind, Andreas A.; McBride, Cameron K.

2012-04-10

We investigate the radial distribution of galaxies within their host dark matter halos as measured in the Sloan Digital Sky Survey by modeling their small-scale clustering. Specifically, we model the Jiang et al. measurements of the galaxy two-point correlation function down to very small projected separations (10 h{sup -1} kpc {<=} r {<=} 400 h{sup -1} kpc), in a wide range of luminosity threshold samples (absolute r-band magnitudes of -18 up to -23). We use a halo occupation distribution framework with free parameters that specify both the number and spatial distribution of galaxies within their host dark matter halos. Wemore » assume one galaxy resides in the halo center and additional galaxies are considered satellites that follow a radial density profile similar to the dark matter Navarro-Frenk-White (NFW) profile, except that the concentration and inner slope are allowed to vary. We find that in low luminosity samples (M{sub r} < -19.5 and lower), satellite galaxies have radial profiles that are consistent with NFW. M{sub r} < -20 and brighter satellite galaxies have radial profiles with significantly steeper inner slopes than NFW (we find inner logarithmic slopes ranging from -1.6 to -2.1, as opposed to -1 for NFW). We define a useful metric of concentration, M{sub 1/10}, which is the fraction of satellite galaxies (or mass) that are enclosed within one-tenth of the virial radius of a halo. We find that M{sub 1/10} for low-luminosity satellite galaxies agrees with NFW, whereas for luminous galaxies it is 2.5-4 times higher, demonstrating that these galaxies are substantially more centrally concentrated within their dark matter halos than the dark matter itself. Our results therefore suggest that the processes that govern the spatial distribution of galaxies, once they have merged into larger halos, must be luminosity dependent, such that luminous galaxies become poor tracers of the underlying dark matter.« less

Dynamically Close Pairs of Galaxies Selected in the NIR

NASA Astrophysics Data System (ADS)

Keenan, Ryan C.; Foucaud, Sebastien; De Propris, Roberto; Lin, Jing-Hua

2013-07-01

Studies of dynamically close pairs of galaxies can serve as a powerful probe of the galaxy merger rate and its evolution. Here we present a large sample of dynamically close pairs of galaxies selected in the K-band from the UKIDSS LAS. These data span ~ 175 deg2 on the sky in the 2dFGRS equatorial region (10 h < RA < 14h). Combining the 2dFGRS redshifts with those from the SDSS, our K-band selected catalog is > 90% spectroscopically complete at K AB < 16.4. In this study, we focus on quantifying the relative contributions of wet, dry, and mixed mergers to the stellar mass buildup of galaxies over the past 1-2 Gyr.