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- ID:
- ivo://CDS.VizieR/J/ApJS/122/355
- Title:
- Properties of low z QSO absorption systems
- Short Name:
- J/ApJS/122/355
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (Partial): We examine the clustering properties of low-redshift Ly{alpha} and heavy-element QSO absorption line systems seen in the spectra of 13 QSOs at the Galactic poles. This is the densest sample of ~1 degree separated QSOs observed spectroscopically with the Hubble Space Telescope to date. At the median redshift of the Ly{alpha} sample (z{=~}0.7), the QSO lines of sight are separated on transverse scales from about 15 to 200h^-1^Mpc (q_0_=0.5, H=100h.km/s/Mpc), allowing the three-dimensional clustering of the absorbers to be examined on those scales. The Galactic poles are also regions where relatively deep and wide-field galaxy redshift surveys have taken place, so the distributions of galaxies and Ly{alpha} systems can be compared within the same volume of space. There are 545 total absorption lines detected in the complete sample from 13 QSOs. We identify 307 Ly{alpha} systems, of which 18 contain heavy-element lines. We confirm the relatively slow redshift number density evolution for Ly systems at z{<=}1. There are also five likely C IV doublets in our sample, for which the Ly{alpha} line is not accessible.
- ID:
- ivo://CDS.VizieR/J/ApJ/690/644
- Title:
- Properties of SDSS QSOs in the ChaMP
- Short Name:
- J/ApJ/690/644
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the spectral energy distributions and evolution of a large sample of optically selected quasars from the Sloan Digital Sky Survey that were observed in 323 Chandra images analyzed by the Chandra Multiwavelength Project. Our highest-confidence matched sample includes 1135 X-ray detected quasars in the redshift range 0.2<z<5.4, representing some 36Msec of effective exposure. We provide catalogs of QSO properties, and describe our novel method of calculating X-ray flux upper limits and effective sky coverage. Spectroscopic redshifts are available for about 1/3 of the detected sample; elsewhere, redshifts are estimated photometrically. We detect 56 QSOs with redshift z>3, substantially expanding the known sample. We find no evidence for evolution out to z~5 for either the X-ray photon index {Gamma} or for the ratio of optical/UV to X-ray flux {alpha}_ox_.
- ID:
- ivo://CDS.VizieR/J/ApJ/797/138
- Title:
- Properties of SMG lens candidates
- Short Name:
- J/ApJ/797/138
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Keck-Adaptive Optics and Hubble Space Telescope high resolution near-infrared (IR) imaging for 500{mu}m bright candidate lensing systems identified by the Herschel Multi-tiered Extragalactic Survey and Herschel Astrophysical Terahertz Large Area Survey. Out of 87 candidates with near-IR imaging, 15 (~17%) display clear near-IR lensing morphologies. We present near-IR lens models to reconstruct and recover basic rest-frame optical morphological properties of the background galaxies from 12 new systems. Sources with the largest near-IR magnification factors also tend to be the most compact, consistent with the size bias predicted from simulations and previous lensing models for submillimeter galaxies (SMGs). The rest-frame optical properties of our sample of Herschel-selected lensed SMGs are consistent with those of unlensed SMGs, which suggests that the two populations are similar.
- ID:
- ivo://CDS.VizieR/J/ApJ/789/23
- Title:
- Properties of SN host galaxies
- Short Name:
- J/ApJ/789/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spectra of broad-lined Type Ic supernovae (SNe Ic-BL), the only kind of SN observed at the locations of long-duration gamma-ray bursts (LGRBs), exhibit wide features indicative of high ejecta velocities (~0.1c). We study the host galaxies of a sample of 245 low-redshift (z < 0.2) core-collapse SNe, including 17 SNe Ic-BL, discovered by galaxy-untargeted searches, and 15 optically luminous and dust-obscured z < 1.2 LGRBs. We show that, in comparison with Sloan Digital Sky Survey galaxies having similar stellar masses, the hosts of low-redshift SNe Ic-BL and z < 1.2 LGRBs have high stellar mass and star formation rate densities. Core-collapse SNe having typical ejecta velocities, in contrast, show no preference for such galaxies. Moreover, we find that the hosts of SNe Ic-BL, unlike those of SNe Ib/Ic and SNe II, exhibit high gas velocity dispersions for their stellar masses. The patterns likely reflect variations among star-forming environments and suggest that LGRBs can be used as probes of conditions in high-redshift galaxies. They may be caused by efficient formation of massive binary progenitor systems in densely star-forming regions, or, less probably, a higher fraction of stars created with the initial masses required for an SN Ic-BL or LGRB. Finally, we show that the preference of SNe Ic-BL and LGRBs for galaxies with high stellar mass and star formation rate densities cannot be attributed to a preference for low metal abundances but must reflect the influence of a separate environmental factor.
- ID:
- ivo://CDS.VizieR/J/ApJ/788/119
- Title:
- Properties of the highly ionized gas of quasars
- Short Name:
- J/ApJ/788/119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first results from our NASA Keck Observatory Database of Ionized Absorbers toward Quasars (KODIAQ) survey which aims to characterize the properties of the highly ionized gas of galaxies and their circumgalactic medium (CGM) at 2<z<4. We select absorbers optically thick at the Lyman limit ({tau}_LL_>1, logN_HI_>17.3}) as probes of these galaxies and their CGM where both transitions of the O VI doublet have little contamination from the Ly{alpha}, {beta} forests. We found 20 absorbers that satisfy these rules: 7 Lyman limit systems (LLSs), 8 super-LLSs (SLLSs) and 5 damped Ly{alpha} (DLAs). The O VI detection rate is 100% for the DLAs, 71% for the LLSs, and 63% for the SLLSs. When O VI is detected, log(N_O VI_)=14.9+/-0.3, an average O VI column density substantially larger and with a smaller dispersion than found in blind O VI surveys at similar redshifts. Strong O VI absorption is therefore nearly ubiquitous in the CGM of z~2-3 galaxies. The total velocity widths of the O VI profiles are also large (200<={Delta}_{upsilon}_O VI_<=400 km/s). These properties are quite similar to those seen for O VI in low-z star-forming galaxies, and therefore we hypothesize that these strong CGM O VI absorbers (with {tau}_LL_>1) at 2<z<~3.5 also probe outflows of star-forming galaxies. The LLSs and SLLSs with no O VI absorption have properties consistent with those seen in cosmological simulations tracing cold streams feeding galaxies. When the highly ionized (Si IV and O VI) gas is taken into account, we determine that the {tau}_LL_>1 absorbers could contain as much as 3%-14% of the cosmic baryon budget at z~2-3, only second to the Ly{alpha} forest. We conservatively show that 5%-20% of the metals ever produced at z~2-3 are in form of highly ionized metals ejected in the CGM of galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/620/A186
- Title:
- Properties of VIS3COS galaxies
- Short Name:
- J/A+A/620/A186
- Date:
- 02 Mar 2022 11:37:55
- Publisher:
- CDS
- Description:
- We present the VIMOS Spectroscopic Survey of a Supercluster in the COSMOS field (VIS^3^COS) at z~0.84. We use VIMOS high-resolution spectra (GG475 filter) to spectroscopically select 490 galaxies in and around the superstructure and an additional 481 galaxies in the line of sight. We present the redshift distribution, the catalogue to be made public, and the first results on the properties of individual galaxies and stacked spectra (3500{AA}<{lambda}<4200{AA} rest-frame). We probe a wide range of densities and environments (from low-density field to clusters and rich groups). We find a decrease in the median star formation rate from low- to high-density environments in all bins of stellar mass and a sharp rise of the quenched fraction {(from ~10% to ~40-60%)} of intermediate-stellar-mass galaxies (10<log_10_M*/M_{sun}_)<10.75) from filaments to clusters. The quenched fraction for massive galaxies shows little dependence on environment, being constant at ~30-40%. We find a break in the strength of the [OII] emission, with nearly constant line equivalent widths at lower densities (~-11{AA}) and then a drop to ~-2.5{AA} towards higher densities. The break in the [OII] line strength happens at similar densities (log_10_(1+{delta})~0.0-0.5) as the observed rise in the quenched fraction. Our results may provide further clues regarding the different environmental processes affecting galaxies with different stellar masses and highlight the advantages of a single dataset in the COSMOS field probing a wide range of stellar masses and environments. We hypothesise that quenching mechanisms are enhanced in high-density regions.
- ID:
- ivo://CDS.VizieR/J/ApJ/696/580
- Title:
- Properties of weak emission-line QSOs (WLQ)
- Short Name:
- J/ApJ/696/580
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Chandra observations of nine high-redshift quasars (z=2.7-5.9) discovered by the Sloan Digital Sky Survey with weak or undetectable high-ionization emission lines in their UV spectra (WLQs). Adding archival X-ray observations of six additional sources of this class has enabled us to place the strongest constraints yet on the X-ray properties of this remarkable class of active galactic nuclei (AGNs). Although our data cannot rule out the possibility that the emission lines are overwhelmed by a relativistically boosted continuum, as manifested by BL Lac objects, we find that WLQs are considerably weaker in the X-ray and radio bands than the majority of BL Lacs found at much lower redshifts. If WLQs are high-redshift BL Lacs, then it is difficult to explain the lack of a large parent population of X-ray and radio bright weak-lined sources at high redshift. We also consider the possibility that WLQs are quasars with extreme properties, and in particular that the emission lines are suppressed by high accretion rates. Using joint spectral fitting of the X-ray spectra of 11 WLQs, we find that the mean photon index in the hard X-ray band is consistent with those observed in typical radio-quiet AGNs with no hint of an unusually steep hard-X-ray spectrum. This result poses a challenge to the hypothesis that WLQs have extremely high accretion rates, and we discuss additional observations required to test this idea.
- ID:
- ivo://CDS.VizieR/J/ApJ/675/1002
- Title:
- Proximate damped Ly{alpha} systems in SDSS-DR5
- Short Name:
- J/ApJ/675/1002
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the Sloan Digital Sky Survey Data Release 5 (SDSS-DR5), we survey proximate damped Ly{alpha} systems (PDLAs): absorption-line systems with HI column density N_H_>=2x10^20^cm^-2^ at velocity separation {delta}v<2999km/s from their background quasar. Many of these absorbers may be physically associated with their background quasars, and their statistics allow us to study quasar environments out to z~5. However, the large ionizing flux emitted by a quasar can ionize the neutral gas in a nearby galaxy, possibly giving rise to a "proximity effect", analogous to the similar effect observed in the Ly{alpha} forest. From a sample of 108 PDLAs, we measure the HI frequency distribution f(N_H_,X) incidence, and gas mass density of the PDLAs near luminous quasars over the redshift interval z=2.2-5. The incidence and mass density of PDLAs at z~3 is approximately twice that of intervening DLAs, while at z<2.5 and >3.5 the f(N_H_X) distribution is enhanced but statistically consistent with the intervening population. We interpret the observed enhancement of PDLAs around quasars in terms of quasar-galaxy clustering and compare the strength of the clustering signal to the expectation from independent measures of the respective clustering strengths of DLAs and quasars, as well as a complementary analysis of the clustering of absorbers around quasars in the transverse direction. We find that there are a factor of 5-10 fewer PDLAs around quasars than expected and interpret this result as evidence for the hypothesis that the ionizing flux from the quasars photoevaporates HI in nearby DLA galaxies, thus reducing their cross section for DLA absorption. This constitutes the first detection of a "proximity effect" for DLAs.
- ID:
- ivo://CDS.VizieR/J/ApJ/795/44
- Title:
- PS1 SNe Ia (0.02<z<0.7) griz light curves
- Short Name:
- J/ApJ/795/44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present griz_P1_ light curves of 146 spectroscopically confirmed Type Ia supernovae (SNe Ia; 0.03<z<0.65) discovered during the first 1.5yr of the Pan-STARRS1 Medium Deep Survey. The Pan-STARRS1 natural photometric system is determined by a combination of on-site measurements of the instrument response function and observations of spectrophotometric standard stars. We find that the systematic uncertainties in the photometric system are currently 1.2% without accounting for the uncertainty in the Hubble Space Telescope Calspec definition of the AB system. A Hubble diagram is constructed with a subset of 113 out of 146 SNe Ia that pass our light curve quality cuts. The cosmological fit to 310 SNe Ia (113 PS1 SNe Ia + 222 light curves from 197 low-z SNe Ia), using only supernovae (SNe) and assuming a constant dark energy equation of state and flatness, yields {omega}=-1.120_-0.206_^+0.360^(Stat)_-0.291_^+0.269^(Sys). When combined with BAO+CMB(Planck)+H_0_, the analysis yields {Omega}_M_=0.280_-0.012_^+0.013^ and {omega}=-1.166_-0.069_^+0.072^ including all identified systematics. The value of w is inconsistent with the cosmological constant value of -1 at the 2.3{sigma} level. Tension endures after removing either the baryon acoustic oscillation (BAO) or the H_0_ constraint, though it is strongest when including the H_0_ constraint. If we include WMAP9 cosmic microwave background (CMB) constraints instead of those from Planck, we find {omega}=-1.124_-0.065_^+0.083^, which diminishes the discord to <2{sigma}. We cannot conclude whether the tension with flat {Lambda}CDM is a feature of dark energy, new physics, or a combination of chance and systematic errors. The full Pan-STARRS1 SN sample with ~three times as many SNe should provide more conclusive results.
