Search

Start Over Capability Type Simple Cone Search
16351. Ultra-deep catalog of X-ray groups in ECDF-S
ID:
ivo://CDS.VizieR/J/A+A/576/A130
Title:
Ultra-deep catalog of X-ray groups in ECDF-S
Short Name:
J/A+A/576/A130
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the detection, identification and calibration of extended sources in the deepest X-ray dataset to date, the Extended Chandra Deep Field South (ECDF-S). Ultra-deep observations of ECDF-S with Chandra and XMM-Newton enable a search for extended X-ray emission down to an unprecedented flux of 2x10^-16^ergs/s/cm^2^. By using simulations and comparing them with the Chandra and XMM data, we show that it is feasible to probe extended sources of this flux level, which is 10000 times fainter than the first X-ray group catalogs of the ROSAT all sky survey. Extensive spectroscopic surveys at the VLT and Magellan have been completed, providing spectroscopic identification of galaxy groups to high redshifts. Furthermore, available HST imaging enables a weak-lensing calibration of the group masses. We present the search for the extended emission on spatial scales of 32" in both Chandra and XMM data, covering 0.3 square degrees and model the extended emission on scales of arcminutes. We present a catalog of 46 spectroscopically identified groups, reaching a redshift of 1.6. We show that the statistical properties of ECDF-S, such as logN-logS and X-ray luminosity function are broadly consistent with LCDM, with the exception that dn/dz/d{Omega} test reveals that a redshift range of 0.2<z<0.5 in ECDF-S is sparsely populated. The lack of nearby structure, however, makes studies of high-redshift groups particularly easier both in X-rays and lensing, due to a lower level of clustered foreground. We present one and two point statistics of the galaxy groups as well as weak-lensing analysis to show that the detected low-luminosity systems are indeed low-mass systems. We verify the applicability of the scaling relations between the X-ray luminosity and the total mass of the group, derived for the COSMOS survey to lower masses and higher redshifts probed by ECDF-S by means of stacked weak lensing and clustering analysis, constraining any possible departures to be within 30% in mass. Ultra-deep X-ray surveys uniquely probe the low-mass galaxy groups across a broad range of redshifts. These groups constitute the most common environment for galaxy evolution. Together with the exquisite data set available in the best studied part of the Universe, the ECDF-S group catalog presented here has an exceptional legacy value.
16352. Ultradeep catalog of X-ray point sources in the GC
ID:
ivo://CDS.VizieR/J/ApJS/235/26
Title:
Ultradeep catalog of X-ray point sources in the GC
Short Name:
J/ApJS/235/26
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present an updated catalog of X-ray point sources in the inner 500" (~20pc) of the Galactic center (GC), where the nuclear star cluster (NSC) stands, based on a total of ~4.5Ms of Chandra observations taken from 1999 September to 2013 April. This ultradeep data set offers unprecedented sensitivity for detecting X-ray sources in the GC, down to an intrinsic 2-10keV luminosity of 1.0x10^31^erg/s. A total of 3619 sources are detected in the 2-8keV band, among which ~3500 are probable GC sources and ~1300 are new identifications. The GC sources collectively account for ~20% of the total 2-8keV flux from the inner 250" region where detection sensitivity is the greatest. Taking advantage of this unprecedented sample of faint X-ray sources that primarily traces the old stellar populations in the NSC, we revisit global source properties, including long-term variability, cumulative spectra, luminosity function, and spatial distribution. Based on the equivalent width and relative strength of the iron lines, we suggest that in addition to the arguably predominant population of magnetic cataclysmic variables (CVs), nonmagnetic CVs contribute substantially to the detected sources, especially in the lower-luminosity group. On the other hand, the X-ray sources have a radial distribution closely following the stellar mass distribution in the NSC, but much flatter than that of the known X-ray transients, which are presumably low-mass X-ray binaries (LMXBs) caught in outburst. This, together with the very modest long-term variability of the detected sources, strongly suggests that quiescent LMXBs are a minor (less than a few percent) population.
16353. Ultradeep Ks imaging in the GOODS-N
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.
16354. Ultra-deep near-IR observation in HDF-S
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.
16355. Ultradiffuse galaxies found in deep HST images of HFF
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.
16356. Ultra-diffuse galaxies with spectroscopic obs.
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.
16357. Ultra-diffuse & LSB dwarf galaxies in A370 from HFF
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.
16358. Ultra hard X-ray AGNs in the Swift/BAT survey
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.
16359. Ultra-luminous infrared galaxies in SDSS-DR6
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.
16360. 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.

Limit your search

more »

more »

more »

more »

more »

more »