- ID:
- ivo://CDS.VizieR/J/AJ/141/137
- Title:
- Pittsburgh SDSS Mg II QSO catalog
- Short Name:
- J/AJ/141/137
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of intervening Mg II quasar absorption-line systems in the redshift interval 0.36<=z<=2.28. The catalog was built from Sloan Digital Sky Survey Data Release Four (SDSS DR4, Cat. II/267) quasar spectra. Currently, the catalog contains ~17000 measured Mg II doublets. We also present data on the ~44600 quasar spectra which were searched to construct the catalog, including redshift and magnitude information, continuum-normalized spectra, and corresponding arrays of redshift-dependent minimum rest equivalent widths detectable at our confidence threshold. The catalog is available online. A careful second search of 500 random spectra indicated that, for every 100 spectra searched, approximately one significant Mg II system was accidentally rejected. Current plans to expand the catalog beyond DR4 quasars are discussed. Many Mg II absorbers are known to be associated with galaxies. Therefore, the combination of large size and well understood statistics makes this catalog ideal for precision studies of the low-ionization and neutral gas regions associated with galaxies at low to moderate redshift. An analysis of the statistics of Mg II absorbers using this catalog will be presented in a subsequent paper.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/369/449
- Title:
- PKS 0405-385 flux-density monitoring
- Short Name:
- J/MNRAS/369/449
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The quasar PKS 0405-385 is one of three radio sources (the other two are PKS 1257-326 and J1819+385) which exhibit unusually strong and rapid interstellar scintillations at GHz frequencies. Such a behaviour suggests a nearby (<30pc away) scattering screen along the line of sight to these radio sources. While quasars PKS 1257-326 and J1819+385 scintillate continuously over several years of monitoring, PKS 0405-385 shows episodes of strong scintillations which last only a few months. Here, I present the results of flux-density monitoring of PKS 0405-385 over 6yr at four Stokes parameters and four frequencies. Two explanations of the episodic behaviour of interstellar scintillation in this source are discussed; morphological evolution of the source and changes in the properties of the interstellar medium along the line of sight.
- ID:
- ivo://CDS.VizieR/J/A+A/637/A7
- Title:
- PKS1830-211 HDO, ND and NH_2_D spectra
- Short Name:
- J/A+A/637/A7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Deuterium and lithium are light elements of high cosmological and astrophysical importance. In this work we report the first detection of deuterated molecules and a search for lithium hydride, ^7^LiH, at redshift z=0.89 in the spiral galaxy intercepting the line of sight to the quasar PKS 1830-211. We used ALMA to observe several submillimeter lines of ND, NH_2_D, and HDO, and their related isotopomers NH_2_, NH_3_, and H^18^_2_O, in absorption against the southwest image of the quasar, allowing us to derive XD/XH abundance ratios. The absorption spectra mainly consist of two distinct narrow velocity components for which we find remarkable differences. One velocity component shows XD/XH abundances that is about 10 times larger than the primordial elemental D/H ratio, and no variability of the absorption profile during the time span of our observations. In contrast, the other component shows a stronger deuterium fractionation. Compared to the first component, this second component has XD/XH abundances that are 100 times larger than the primordial D/H ratio, a deepening of the absorption by a factor of two within a few months, and a rich chemical composition, with relative enhancements of N_2_H^+^, CH_3_OH, SO_2_ and complex organic molecules. We therefore speculate that this component is associated with the analog of a Galactic dark cloud, while the first component is likely more diffuse. Our search for the ^7^LiH (1-0) line was unsuccessful and we derive an upper limit ^7^LiH/H_2_=4x10^-13^ (3{sigma}) in the z=0.89 absorber toward PKS 1830.211. Besides, with ALMA archival data, we could not confirm the previous tentative detections of this line in the z=0.68 absorber toward B0218+357; we derive an upper limit ^7^LiH/H_2_=5x10^-11^ (3{sigma}), although this is less constraining than our limit toward PKS 1830.211. We conclude that, as in the Milky Way, only a tiny fraction of lithium nuclei are possibly bound in LiH in these absorbers at intermediate redshift.
- ID:
- ivo://CDS.VizieR/J/ApJ/676/262
- Title:
- PKS1302-102 intergalactic absorption system
- Short Name:
- J/ApJ/676/262
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a detailed analysis of the intergalactic metal-line absorption systems in the archival HST STIS and FUSE ultraviolet spectra of the low-redshift quasar PKS 1302-102 (z_QSO_=0.2784). We supplement the archive data with CLOUDY ionization models and a survey of galaxies in the quasar field.
- ID:
- ivo://CDS.VizieR/J/A+A/643/A174
- Title:
- PKS J1209-2032 & CGRaBS J1549+5038 radio spectra
- Short Name:
- J/A+A/643/A174
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the detection of HI 21-cm absorption in a member of the rare and recently discovered class of compact radio sources, "Extremely Inverted Spectrum Extragalactic Radio Sources (EISERS)" . EISERS conceivably form a special sub-class of the inverted spectrum radio galaxies since the spectral index of the optically thick part of the spectrum for these sources crosses the synchrotron self absorption limit of {alpha}=+2.5 (S({nu}) {prop.to} {nu}^{alpha}^). We have searched for HI absorption in two EISERS using the recently upgraded Giant Metrewave Radio Telescope (uGMRT) and detected an absorption feature in one of them. The strong associated HI absorption detected against the source J1209-2032 (z=0.4040) implies an optical depth of 0.178+/-0.02 corresponding to an HI column density of 34.8+/-2.9x10^20^cm^-2^, for an assumed HI spin temperature of 100K and covering factor of 1. This is among the highest known optical depth and HI column densities found for compact radio sources of peaked spectrum type and supports the free-free absorption model for the steeply inverted radio spectrum of this source. For the other source, J1549+5038 (z=2.171), no HI absorption was detected in our observations.
- ID:
- ivo://CDS.VizieR/J/A+A/648/A116
- Title:
- PKS 1830-211 OH and HI spectra
- Short Name:
- J/A+A/648/A116
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The Large Survey Project (LSP) "MeerKAT Absorption Line Survey" (MALS) is a blind HI 21-cm and OH 18-cm absorption line survey in the L- and UHF-bands, with the primary goal to better determine the occurrence of atomic and molecular gas in the circumgalactic and inter-galactic medium, and its redshift evolution. Here we present the first results using the UHF-band, obtained towards the strongly lensed radio source PKS 1830-211, detecting absorption produced by the lensing galaxy. With merely 90 mins of data acquired on-source for science verification and processed using the Automated Radio Telescope Imaging Pipeline (ARTIP), we detect in absorption the known HI 21-cm and OH 18-cm main lines at z=0.89 at an unprecedented signal-to-noise ratio (4000 in the continuum, in each 6km/s wide channel). For the first time we report the detection at z=0.89 of OH satellite lines, so far not detected at z>0.25. We decompose the OH lines into a thermal and a stimulated contribution, where the 1612 and 1720MHz lines are conjugate. The total OH 1720MHz emission line luminosity is 6100L_{sun}_. This is the most luminous known 1720MHz maser line. It is also among the highest luminosities for the OH-main lines megamasers. The absorption components of the different images of the background source sample different light paths in the lensing galaxy, and their weights in the total absorption spectrum are expected to vary in time, on daily and monthly time scales. We compare our normalized spectra with those obtained more than 20yrs ago, and find no variation, in spite of the high signal-to-noise ratios. We interpret the absorption spectra with the help of a lens galaxy model, derived from an N-body hydro-dynamical simulation, with a morphology similar to its optical HST image. The resulting absorption lines depend mainly on the background continuum, and the radial distribution of the gas surface density, for each atomic /molecular species.We show that it is possible to reproduce the observations assuming a realistic spiral galaxy disk, without invoking any central gas outflows. There are, however, distinct and faint high-velocity features in the ALMA millimeter absorption spectra, that most likely originate from high-velocity clouds or tidal features. These clouds may contribute to broaden the Hi and OH spectra.
- ID:
- ivo://CDS.VizieR/J/A+A/595/A128
- Title:
- PKS 1830-211 OH+ and H2O+ spectra
- Short Name:
- J/A+A/595/A128
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the detection of OH^+^ and H_2_O^+^ in the z=0.89 absorber toward the lensed quasar PKS 1830-211. The abundance ratio of OH^+^ and H_2_O^+^ is used to quantify the molecular hydrogen fraction (fH2) and the cosmic-ray ionization rate of atomic hydrogen ({dzeta}_H_) along two lines of sight, located at ~2kpc and ~kpc to either side of the absorber's center. The molecular fraction decreases outwards, from ~0.04 to ~0.02, comparable to values measured in the Milky Way at similar galactocentric radii. For {dzeta}_H_, we find values of ~2x10^-14^s^-1^ and ~3x10^-15^s^-1^, respectively, which are slightly higher than in the Milky Way at comparable galactocentric radii, possibly due to a higher average star formation activity in the z=0.89 absorber. The ALMA observations of OH^+^, H_2_O^+^, and other hydrides toward PKS 1830-211 reveal the multi-phase composition of the absorbing gas. Taking the column density ratios along the southwest and northeast lines of sight as a proxy of molecular fraction, we classify the species ArH^+^, OH^+^, H_2_Cl^+^, H_2_O^+^, CH, and HF as tracing gases increasingly more molecular. Incidentally, our data allow us to improve the accuracy of H_2_O^+^ rest frequencies and thus refine the spectroscopic parameters.
- ID:
- ivo://CDS.VizieR/J/A+A/541/A160
- Title:
- Planck + X/{gamma} observations of blazars
- Short Name:
- J/A+A/541/A160
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present simultaneous Planck, Swift, Fermi, and ground-based data for 105 blazars belonging to three samples with flux limits in the soft X-ray, hard X-ray, and {gamma}-ray bands, with additional 5GHz flux-density limits to ensure a good probability of a Planck detection. We compare our results to those of a companion paper presenting simultaneous Planck and multi-frequency observations of 104 radio-loud northern active galactic nuclei selected at radio frequencies. While we confirm several previous results, our unique data set allows us to demonstrate that the selection method strongly influences the results, producing biases that cannot be ignored.
- ID:
- ivo://CDS.VizieR/J/A+A/427/107
- Title:
- Polarization in BAL QSOs
- Short Name:
- J/A+A/427/107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of several statistical tests performed on a large sample of 139 broad absorption line (BAL) QSOs with good quality optical spectra and/or optical polarization data. Correlations between ten optical indices and the polarization degree p_0_ are systematically searched for.
- ID:
- ivo://CDS.VizieR/J/ApJ/512/125
- Title:
- Polarization of broad absorption line QSOs
- Short Name:
- J/ApJ/512/125
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the combined results of optical polarization surveys of QSOs showing broad absorption lines (BALQSOs) conducted at the Steward and McDonald Observatories. The merged list of 53 objects provides the first statistical justification for claims of the tendency of BALQSOs to show stronger than average polarization, with a typical BALQSO being polarized a factor 2.4 times greater than a QSO from an optical survey selected without regard for absorption lines. Spectropolarimetry of sufficient quality to distinguish the polarization of emission lines versus absorption troughs versus continuum is also presented for six objects from the survey.
