- ID:
- ivo://CDS.VizieR/J/ApJ/614/75
- Title:
- Lyman{alpha} emitting galaxies at z=2.38
- Short Name:
- J/ApJ/614/75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In Paper 1 (Palunas et al., 2004ApJ...602..545P) of this series we identified an 80 comoving Mpc filament of candidate Ly{alpha}-emitting galaxies at redshift 2.38. In this paper we present spectroscopy of the 37 galaxy candidates. Our spectroscopy reached a surface brightness limit of 5.0x10^-17^erg/cm^2^/s/arcsec^2^. Of the 14 candidates down to this limit, 12 were confirmed to be Ly{alpha}-emitting galaxies at the filament redshift. We also obtained spectral confirmation for six of the lower surface brightness candidates, all of which also lay at the filament redshift. In addition, we identify a foreground cluster of QSOs at z=1.65.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/391/L11
- Title:
- Lyman alpha forest in HE 0515-4414
- Short Name:
- J/A+A/391/L11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigated HST/STIS and VLT/UVES spectra of the bright QSO HE 0515-4414 (z_em_=1.73, B=15.0) to study the Lyman alpha forest in the redshift range 0.9 < z < 1.7 at a resolution <10km/s.
- ID:
- ivo://CDS.VizieR/J/MNRAS/391/1457
- Title:
- Lyman{alpha} forest in QSO pairs
- Short Name:
- J/MNRAS/391/1457
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We look for signs of the HI transverse proximity effect in the spectra of 130 quasi-stellar object (QSO) pairs, most with transverse separations in the plane of the sky of 0.1-3Mpc at z~2.2. We expected to see a decrease in Ly{alpha} forest HI absorption in the spectrum of background QSOs near the position of foreground QSOs. Instead, we see no change in the absorption in front of the foreground QSOs, and we see evidence for a 50 per cent increase in the absorption out to 6Mpc behind the foreground QSOs. Further, we see no change in the HI absorption along the line-of-sight to the foreground QSOs, the normal line-of-sight proximity effect. We may account for the lack of change in the HI absorption if the effect of extra ultraviolet photons is cancelled by higher gas density around QSOs. If so, the increase in absorption behind the QSOs then suggests that the higher gas density there is not cancelled by the UV radiation from the QSOs. We can explain our observations if QSOs have had their current UV luminosities for less than approximately a million years, a time-scale that has been suggested for accretion disc instabilities and gas depletion.
- 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.
- 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.
- 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.
- 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.
- 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).
- 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.
- 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.
