- ID:
- ivo://CDS.VizieR/J/ApJS/187/251
- Title:
- Ultradeep Ks imaging in the GOODS-N
- Short Name:
- J/ApJS/187/251
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an ultradeep K_s_-band image that covers 0.5x0.5deg^2^ centered on the Great Observatories Origins Deep Survey-North (GOODS-N). The image reaches a 5{sigma} depth of K_s,AB_=24.45 in the GOODS-N region, which is as deep as the GOODS-N Spitzer Infrared Array Camera (IRAC) 3.6um image. We present a new method of constructing IRAC catalogs that uses the higher spatial resolution K_s_ image and catalog as priors and iteratively subtracts fluxes from the IRAC images to estimate the IRAC fluxes. Our iterative method is different from the {chi}^2^ approach adopted by other groups. We verified our results using data taken in two different epochs of observations, as well as by comparing our colors with the colors of stars and with the colors derived from model spectral energy distributions of galaxies at various redshifts. We make available to the community our WIRCam K_s_-band image and catalog (94951 objects in 0.25deg^2^), the Interactive Data Language pipeline used for reducing the WIRCam images, and our IRAC 3.6-8.0um catalog (16950 objects in 0.06deg^2^ at 3.6um). With this improved K_s_ and IRAC catalog and a large spectroscopic sample from our previous work (Cat. <J/ApJ/689/687>), we study the color-magnitude and color-color diagrams of galaxies. We compare the effectiveness of using K_s_ and IRAC colors to select active galactic nuclei and galaxies at various redshifts. We also study a color selection of z=0.65-1.2 galaxies using the K_s_, 3.6um, and 4.5um bands.
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- ID:
- ivo://CDS.VizieR/J/AJ/125/1107
- Title:
- Ultra-deep near-IR observation in HDF-S
- Short Name:
- J/AJ/125/1107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep near-infrared (NIR) Js-, H-, and Ks-band ISAAC imaging of the Wide Field Planetary Camera 2 (WFPC2) field of the Hubble Deep Field South (HDF-S). The 2.5'x2.5' high Galactic latitude field was observed with the Very Large Telescope under the best seeing conditions, with integration times amounting to 33.6hr in Js, 32.3hr in H, and 35.6hr in Ks. We reach total AB magnitudes for point sources of 26.8, 26.2, and 26.2, respectively (3sigma), which make it the deepest ground-based NIR observation to date and the deepest Ks-band data in any field. The effective seeing of the co-added images is ~0.45" in Js, ~0.48" in H, and ~0.46" in Ks. Using published WFPC2 optical data, we constructed a Ks-limited multicolor catalog containing 833 sources down to K^tot^_s,AB_<~26, of which 624 have seven-band optical-to-NIR photometry. These data allow us to select normal galaxies from their rest-frame optical properties to high redshift (z<~4). The observations, data reduction, and properties of the final images are discussed, and we address the detection and photometry procedures that were used in making the catalog. In addition, we present deep number counts, color distributions, and photometric redshifts of the HDF-S galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/844/157
- Title:
- Ultradiffuse galaxies found in deep HST images of HFF
- Short Name:
- J/ApJ/844/157
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the detection of a large population of ultradiffuse galaxies (UDGs) in two massive galaxy clusters, Abell S1063 at z=0.348 and Abell 2744 at z=0.308, based on F814W and F105W images in the Hubble Frontier Fields Program. We find 47 and 40 UDGs in Abell S1063 and Abell 2744, respectively. Color-magnitude diagrams of the UDGs show that they are mostly located at the faint end of the red sequence. From the comparison with simple stellar population models, we estimate their stellar mass to range from 10^8^ to 10^9^M_{sun}_. Radial number density profiles of the UDGs show a turnover or a flattening in the central region at r<100kpc. We estimate the total masses of the UDGs using the galaxy scaling relations. A majority of the UDGs have total masses M_200_=10^10^-10^11^M_{sun}_, and only a few of them have total masses M_200_=10^11^-10^12^M_{sun}_. The total number of UDGs within the virial radius is estimated to be N(UDG)=770+/-114 for Abell S1063 and N(UDG)=814+/-122 for Abell 2744. Combining these results with data in the literature, we fit the relation between the total numbers of UDGs and the masses of their host systems for M_200_>10^13^M_{sun}_ with a power law, N(UDG)=M_200_^1.05+/-0.09^. These results suggest that a majority of the UDGs have a dwarf galaxy origin, while only a small number of the UDGs are massive L* galaxies that failed to form a normal population of stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/923/257
- Title:
- Ultra-diffuse galaxies with spectroscopic obs.
- Short Name:
- J/ApJ/923/257
- Date:
- 14 Mar 2022 07:42:35
- Publisher:
- CDS
- Description:
- We present new redshift measurements for 19 candidate ultra-diffuse galaxies (UDGs) from the Systematically Measuring Ultra-Diffuse Galaxies (SMUDGes) survey after conducting a long-slit spectroscopic follow-up campaign on 23 candidates with the Large Binocular Telescope. We combine these results with redshift measurements from other sources for 29 SMUDGes and 20 non-SMUDGes candidate UDGs. Together, this sample yields 44 spectroscopically confirmed UDGs (r_e_>=1.5kpc and {mu}_g_(0)>=24mag/arcsec^2^ within uncertainties) and spans cluster and field environments, with all but one projected on the Coma cluster and environs. We find no statistically significant differences in the structural parameters of cluster and noncluster confirmed UDGs, although there are hints of differences among the axis ratio distributions. Similarly, we find no significant structural differences among those in locally dense or sparse environments. However, we observe a significant difference in color with respect to projected clustercentric radius, confirming trends observed previously in statistical UDG samples. This trend strengthens further when considering whether UDGs reside in either cluster or locally dense environments, suggesting starkly different star formation histories for UDGs residing in high- and low-density environments. Of the 16 large (r_e_>=3.5kpc) UDGs in our sample, only one is a field galaxy that falls near the early-type galaxy red sequence. No other field UDGs found in low-density environments fall near the red sequence. This finding, in combination with our detection of Galaxy Evolution Explorer NUV flux in nearly half of the UDGs in sparse environments, suggests that field UDGs are a population of slowly evolving galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/894/75
- Title:
- Ultra-diffuse & LSB dwarf galaxies in A370 from HFF
- Short Name:
- J/ApJ/894/75
- Date:
- 19 Jan 2022 13:03:46
- Publisher:
- CDS
- Description:
- We report the discovery of ultra-diffuse galaxies (UDGs) in Abell 370 (A370; z=0.375). We find 46 UDGs in A370 from the images of the Hubble Frontier Fields. Most UDGs are low-luminosity red sequence galaxies, while a few of them are blue UDGs. We estimate the abundance of UDGs in A370, N(UDG)=644+/-104. Combining these results with those of Abell S1063 (z=0.348) and Abell 2744 (z=0.308), we derive a mean radial number density profile of UDGs in the three clusters. The number density profiles of UDGs and bright galaxies show a discrepancy in the central region of the clusters: the profile of UDGs shows a flattening as clustercentric distance decreases, while that of bright galaxies shows a continuous increase. This implies that UDGs are prone to disruption in the central region of the clusters. The relation between the abundance of UDGs and virial masses of their host systems is described by a power law with an index of nearly one: N(UDG){propto}M_200_^0.99+/-0.05^ for M_200_>10^13^M_{sun}_. We estimate approximately dynamical masses of UDGs using the fundamental manifold method and find that most UDGs have dwarf-like masses (M_200_<10^11^M_{sun}_). This implies that most UDGs have a dwarf-like origin and a small number of them could be failed L* galaxies. These results suggest that multiple origins may contribute to the formation and evolution of UDGs in massive galaxy clusters.
- ID:
- ivo://CDS.VizieR/J/ApJ/739/57
- Title:
- Ultra hard X-ray AGNs in the Swift/BAT survey
- Short Name:
- J/ApJ/739/57
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have assembled the largest sample of ultra hard X-ray selected (14-195keV) active galactic nucleus (AGN) with host galaxy optical data to date, with 185 nearby (z<0.05), moderate luminosity AGNs from the Swift BAT sample. The BAT AGN host galaxies have intermediate optical colors (u-r and g-r) that are bluer than a comparison sample of inactive galaxies and optically selected AGNs from the Sloan Digital Sky Survey (SDSS) which are chosen to have the same stellar mass. Based on morphological classifications from the RC3 and the Galaxy Zoo, the bluer colors of BAT AGNs are mainly due to a higher fraction of mergers and massive spirals than in the comparison samples. BAT AGNs in massive galaxies (logM*>10.5) have a 5-10 times higher rate of spiral morphologies than in SDSS AGNs or inactive galaxies. We also see enhanced far-infrared emission in BAT AGN suggestive of higher levels of star formation compared to the comparison samples. BAT AGNs are preferentially found in the most massive host galaxies with high concentration indexes indicative of large bulge-to-disk ratios and large supermassive black holes. The narrow-line (NL) BAT AGNs have similar intrinsic luminosities as the SDSS NL Seyferts based on measurements of [OIII]5007. There is also a correlation between the stellar mass and X-ray emission. The BAT AGNs in mergers have bluer colors and greater ultra hard X-ray emission compared to the BAT sample as a whole.
- ID:
- ivo://CDS.VizieR/J/ApJ/704/789
- Title:
- Ultra-luminous infrared galaxies in SDSS-DR6
- Short Name:
- J/ApJ/704/789
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Ultra-luminous infrared galaxies (ULIRGs) are interesting objects with dramatic properties. Many efforts have been made to understand the physics of their luminous infrared emission and evolutionary stages. However, a large ULIRG sample is still needed to study the properties of their central black holes (BHs), the BH-host galaxy relation, and their evolution. We identified 308 ULIRGs from the Sloan Digital Sky Survey Data Release 6, and classified them into the NL ULIRGs (with only narrow emission lines) and the Type I ULIRGs (with broad emission lines). About 56% of ULIRGs in our total sample show interaction features, and this percentage is 79% for redshift z<0.2. Optical identifications of these ULIRGs show that the active galactic nucleus percentage is at least 49%, and the percentage increases with the infrared luminosity. We found 62 Type I ULIRGs, and estimated their BH masses and velocity dispersions from their optical spectra. Together with known Type I ULIRGs in the literature, a sample of 90 Type I ULIRGs enables us to make a statistical study.
14808. Ultraluminous IRAS galaxies
- ID:
- ivo://CDS.VizieR/J/MNRAS/279/459
- Title:
- Ultraluminous IRAS galaxies
- Short Name:
- J/MNRAS/279/459
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new, large sample of ultraluminous (L_60_>10^11.4^L_{sun}_ for H_0_=100km/s/Mpc) IRAS galaxies selected for the IRAS Faint Source Survey using a novel optical far-infrared colour selection criterion. Our technique proves to be very successful in selecting luminous galaxies, and we present data on 91 ultraluminous objects, of which 65 are newly discovered. Using our redshift spectra and information from the literature we find that at least 35% of these objects are likely to contain an AGN-type central engine. We also find that purely IR-based techniques for determining the presence of an AGN in these objects are unreliable.
- ID:
- ivo://CDS.VizieR/J/ApJS/157/59
- Title:
- Ultraluminous X-ray sources in nearby galaxies
- Short Name:
- J/ApJS/157/59
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- X-ray observations have revealed in other galaxies a class of extranuclear X-ray point sources with X-ray luminosities of 10^39^-10^41^ergs/s, exceeding the Eddington luminosity for stellar mass X-ray binaries. These ultraluminous X-ray sources (ULXs) may be powered by intermediate-mass black holes of a few thousand M_Sun_ or stellar mass black holes with special radiation processes. In this paper, we present a survey of ULXs in 313 nearby galaxies with D_25_>1 within 40Mpc with 467 ROSAT High Resolution Imager (HRI) archival observations. The HRI observations are reduced with uniform procedures, refined by simulations that help define the point source detection algorithm employed in this survey. A sample of 562 extragalactic X-ray point sources with L_X_=10^38^-10^43^ergs/s is extracted from 173 survey galaxies, including 106 ULX candidates within the D_25_ isophotes of 63 galaxies and 110 ULX candidates between 1D_25_ and 2D_25_ of 64 galaxies, from which a clean sample of 109 ULXs is constructed to minimize the contamination from foreground or background objects.
- ID:
- ivo://CDS.VizieR/J/ApJ/847/142
- Title:
- Ultra-metal-poor stars LTE and NLTE abundances
- Short Name:
- J/ApJ/847/142
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new ultra-metal-poor stars parameters with [Fe/H] < -4.0 based on line-by-line non-local thermodynamic equilibrium (NLTE) abundances using an up-to-date iron model atom with a new recipe for non-elastic hydrogen collision rates. We study the departures from LTE in their atmospheric parameters and show that they can grow up to ~1.00dex in [Fe/H], ~150K in Teff and ~0.5dex in logg toward the lowest metallicities. Accurate NLTE atmospheric stellar parameters, in particular [Fe/H] being significantly higher, are the first step to eventually providing full NLTE abundance patterns that can be compared with Population III supernova nucleosynthesis yields to derive properties of the first stars. Overall, this maximizes the potential of these likely second-generation stars to investigate the early universe and how the chemical elements were formed.
