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461. Lyman-alpha forest of 5 QSOs
ID:
ivo://CDS.VizieR/J/MNRAS/335/555
Title:
Lyman-alpha forest of 5 QSOs
Short Name:
J/MNRAS/335/555
Date:
21 Oct 2021
Publisher:
CDS
Description:
Combining a new, increased data set of eight quasi-stellar objects (QSOs) covering the Ly{alpha} forest at redshifts 1.5<z<3.6 from VLT/UVES observations with previously published results, we have investigated the properties of the Ly{alpha} forest at 1.5<z<4. With the six QSOs covering the Ly{alpha} forest at 1.5<z<2.5, we have extended previous studies in this redshift range. In particular, we have concentrated on the evolution of the line number density and the clustering of the Ly{alpha} forest at z<=2.5, where the Ly{alpha} forest starts to show some inhomogeneity from sightline to sightline. We have fitted Voigt profiles to the Ly{alpha} absorption lines as in previous studies, and have, for two QSOs with z_em_~2.4, fitted Ly{alpha} and higher order of Lyman lines down to 3050{AA} simultaneously. This latter approach has been taken in order to study the Ly{beta} forest at z~2.2 and the higher H I column density Ly{alpha} forest in the Ly{beta} forest region.
462. Lyman alpha forest of 55 QSOs
ID:
ivo://CDS.VizieR/J/ApJ/662/72
Title:
Lyman alpha forest of 55 QSOs
Short Name:
J/ApJ/662/72
Date:
21 Oct 2021
Publisher:
CDS
Description:
We examine the evolution of the IGM Ly{alpha} optical depth distribution using the transmitted flux probability distribution function (PDF) in a high-resolution sample of 55 QSOs spanning absorption redshifts 1.7<z<5.8. The data are compared to two theoretical {tau} distributions: a model distribution based on the density distribution of Miralda-Escude et al. (2000ApJ...530....1M; MHR00) and a lognormal distribution.
463. Lyman-Alpha Forest of 3 QSOs
ID:
ivo://CDS.VizieR/J/A+A/373/757
Title:
Lyman-Alpha Forest of 3 QSOs
Short Name:
J/A+A/373/757
Date:
21 Oct 2021
Publisher:
CDS
Description:
The line tables, tablea1.dat, tablea2.dat and tablea3.dat, list the fitted line parameters from Voigt-profile fitting of the Lyman-alpha forest clouds: redshift, z, the Doppler parameter, b, and its density, N. The profile fitting was done with the program VPFIT. The three QSOs, HE0515-4414, J2233-606 and HE2217-2818 were taken with VLT/UVES with a resolution of 45,000 and S/N of 30-50 in the forest regions.
464. Lyman-alpha forest toward PKS 0405-123
ID:
ivo://CDS.VizieR/J/ApJ/636/631
Title:
Lyman-alpha forest toward PKS 0405-123
Short Name:
J/ApJ/636/631
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results for Ly{alpha} forest and metal absorbers from ~7km/s resolution Space Telescope Imaging Spectrograph (STIS) data for QSO PKS 0405-123 (z=0.574). We analyze strong and weak samples of Ly{alpha} forest lines, containing 60 absorbers with column density log N(HI)>=13.3 over 0.002<z<0.423 and 44 with logN(HI)>=13.1 over 0.020<z<0.234, respectively.
465. Lyman cont. luminosity of SDSS quasar pairs at z~3
ID:
ivo://CDS.VizieR/J/ApJ/884/151
Title:
Lyman cont. luminosity of SDSS quasar pairs at z~3
Short Name:
J/ApJ/884/151
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have used spectra of 181 projected quasar pairs at separations <=1.5' from the Sloan Digital Sky Survey Data Release 12 in the redshift range of 2.5-3.5 to probe the proximity regions of the foreground quasars. We study the proximity effect both in the longitudinal and in the transverse directions, by carrying out a comparison of the Ly{alpha} absorption lines originating from the vicinity of quasars to those originating from the general intergalactic medium at the same redshift. We found an enhancement in the transmitted flux within 4Mpc to the quasar in the longitudinal direction. However, the trend is found to be reversed in the transverse direction. In the longitudinal direction, we derived an excess overdensity profile showing an excess up to r<=5Mpc after correcting for the quasar's ionization, taking into account the effect of low spectral resolution. This excess overdensity profile matches with the average overdensity profile in the transverse direction without applying any correction for the effect of the quasar's ionization. Among various possible interpretations, we found that the anisotropic obscuration of the quasar's ionization seems to be the most probable explanation. This is also supported by the fact that all of our foreground quasars happen to be type 1 AGNs. Finally, we constrain the average quasar's illumination along the transverse direction as compared to that along the longitudinal direction to be <=27% (3{sigma} confidence level).
466. Lyman limit absorption systems in z~3 QSOs
ID:
ivo://CDS.VizieR/J/ApJ/775/78
Title:
Lyman limit absorption systems in z~3 QSOs
Short Name:
J/ApJ/775/78
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of a blind survey of Lyman limit systems (LLSs) detected in absorption against 105 quasars at z~3 using the blue sensitive MagE spectrograph at the Magellan Clay telescope. By searching for Lyman limit absorption in the wavelength range {lambda}~3000-4000{AA}, we measure the number of LLSs per unit redshift {ell}(z)=1.21+/-0.28 at z~2.8. Using a stacking analysis, we further estimate the mean free path of ionizing photons in the z~3 universe {lambda}_mfp_^912^=100+/-29h_70.4_^-1^Mpc. Combined with our LLS survey, we conclude that systems with logN_HI_>=17.5/cm2 contribute only ~40% to the observed mean free path at these redshifts. Furthermore, with the aid of photoionization modeling, we infer that a population of ionized and metal poor systems is likely required to reproduce the metal line strengths observed in a composite spectrum of 20 LLSs with log N_HI_~17.5-19/cm2 at z~2.6-3.0. Finally, with a simple toy model, we deduce that gas in the halos of galaxies can alone account for the totality of LLSs at z<~3, but a progressively higher contribution from the intergalactic medium is required beyond z~3.5. We also show how the weakly evolving number of LLSs per unit redshift at z<~3 can be modeled either by requiring that the spatial extent of the circumgalactic medium is redshift invariant in the last ~10Gyr of cosmic evolution or by postulating that LLSs arise in halos that are rare fluctuations in the density field at each redshift.
467. Magellanic Quasars Survey. II. AGNs behind LMC
ID:
ivo://CDS.VizieR/J/ApJ/746/27
Title:
Magellanic Quasars Survey. II. AGNs behind LMC
Short Name:
J/ApJ/746/27
Date:
21 Oct 2021
Publisher:
CDS
Description:
We quadruple the number of quasars known behind the Large Magellanic Cloud (LMC) from 56 (42 in the Optical Gravitational Lensing Experiment (OGLE)-III LMC fields) to 200 by spectroscopically confirming 169 (144 new) quasars from a sample of 845 observed candidates in four ~3 deg^2^ Anglo-Australian Telescope/AAOmega fields south of the LMC center. The candidates were selected based on their Spitzer mid-infrared colors, X-ray emission, and/or optical variability properties in the database of the OGLE microlensing survey. The contaminating sources can be divided into 115 young stellar objects (YSOs), 17 planetary nebulae (PNe), 39 Be and 24 blue stars, 68 red stars, and 12 objects classed as either YSO/PN or blue star/YSO. There are also 402 targets with either featureless spectra or too low signal-to-noise ratios for source classification. Our quasar sample is 50% (30%) complete at I = 18.6 mag (19.3 mag). The newly discovered active galactic nuclei (AGNs) provide many additional reference points for proper motion studies of the LMC, and the sample includes 10 bright AGNs (I < 18 mag) that are potentially suitable for absorption line studies. Their primary use, however, is for detailed studies of quasar variability, as they all have long-term, high cadence, continuously growing light curves from the microlensing surveys of the LMC. Completing the existing Magellanic Quasars Survey fields in the LMC and Small Magellanic Cloud should yield a sample of ~700 well-monitored AGNs, and expanding it to the larger regions covered by the OGLE-IV survey should yield a sample of ~3600 AGNs.
468. Magellanic Quasars Survey: QSOs behind SMC
ID:
ivo://CDS.VizieR/J/ApJS/194/22
Title:
Magellanic Quasars Survey: QSOs behind SMC
Short Name:
J/ApJS/194/22
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the spectroscopic confirmation of 29 new, 12 plausible, and three previously known quasars behind the central ~1.5deg^2^ region of the Small Magellanic Cloud (SMC). These were identified in a single 2df/AAOmega observation on the Anglo-Australian Telescope of 268 candidates selected primarily based on their mid-IR colors, along with a smaller number of optically variable sources in OGLE-II close to known X-ray sources.
469. MAGIICAT. I. MgII Absorber-Galaxy Catalog
ID:
ivo://CDS.VizieR/J/ApJ/776/114
Title:
MAGIICAT. I. MgII Absorber-Galaxy Catalog
Short Name:
J/ApJ/776/114
Date:
21 Oct 2021
Publisher:
CDS
Description:
We describe the MgII Absorber-Galaxy Catalog, MAGIICAT, a compilation of 182 spectroscopically identified intermediate redshift (0.07<=z<=1.1) galaxies with measurements of MgII {lambda}{lambda}2796,2803 absorption from their circumgalactic medium within projected distances of 200kpc from background quasars. In this work, we present "isolated" galaxies, which are defined as having no spectroscopically identified galaxy within a projected distance of 100kpc and a line of sight velocity separation of 500km/s. We standardized all galaxy properties to the {Lambda}CDM cosmology and galaxy luminosities, absolute magnitudes, and rest-frame colors to the B- and K-band on the AB system. We present galaxy properties and rest-frame MgII equivalent width, W_r_(2796), versus galaxy redshift. The well-known anti-correlation between W_r_(2796) and quasar-galaxy impact parameter, D, is significant to the 8{sigma} level. The mean color of MAGIICAT galaxies is consistent with an Sbc galaxy for all redshifts. We also present B- and K-band luminosity functions for different W_r_(2796) and redshift subsamples: "weak absorbing" [W_r_(2796)<0.3{AA}], "strong absorbing" [W_r_(2796)>=0.3{AA}], low redshift (z{<}<z>), and high redshift (z{>=}<z>), where <z> = 0.359 is the median galaxy redshift. Rest-frame color B-K correlates with M_K_ at the 8{sigma} level for the whole sample but is driven by the strong absorbing, high-redshift subsample (6{sigma}). Using M_K_ as a proxy for stellar mass and examining the luminosity functions, we infer that in lower stellar mass galaxies, MgII absorption is preferentially detected in blue galaxies and the absorption is more likely to be weak.
470. Maidanak Observatory Lens Images
ID:
ivo://org.gavo.dc/maidanak/res/rawframes/rawframes
Title:
Maidanak Observatory Lens Images
Date:
22 Jan 2021 08:24:03
Publisher:
The GAVO DC team
Description:
Observations of (mainly) lensed quasars from Maidanak Observatory, Uzbekhistan