- ID:
- ivo://CDS.VizieR/J/MNRAS/427/1135
- Title:
- Properties of radio-loud BAL quasars
- Short Name:
- J/MNRAS/427/1135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We recently presented radio observations of a large sample of radio-loud broad absorption line (BAL) quasars from the Sloan Digital Sky Survey (SDSS) and Faint Images of the Radio Sky at Twenty-cm surveys, as well as a well matched sample of unabsorbed quasars, primarily to measure their radio spectral indices and estimate ensemble orientations. Here, we analyse the SDSS spectra of these samples and compare the rest-frame ultraviolet properties of radio-loud BAL and non-BAL quasars. Ultraviolet properties include the continuum shape, emission-line measurements of CIV, AlIII, CIII], FeII and MgII, and BAL properties including the balnicity index, absorption index and minimum and maximum outflow velocities. We find that radio-loud BAL quasars have similar ultraviolet properties compared to radio-loud non-BAL sources, though they do appear to have redder continua and stronger FeII emission, which is consistent with what is found for radio-quiet BAL sources. No correlations exist between outflow properties and orientation (radio spectral index), suggesting that BAL winds along any line of sight are driven by the same mechanisms. There are also few correlations between spectral index and other properties. We conclude that BAL outflows occur along all lines of sight with similar strengths and velocities.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/776/136
- Title:
- QPQ VI. HI absorption of z~2 quasars
- Short Name:
- J/ApJ/776/136
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- With close pairs of quasars at different redshifts, a background quasar sightline can be used to study a foreground quasar's environment in absorption. We use a sample of 650 projected quasar pairs to study the HI Ly{alpha} absorption transverse to luminous, z~2 quasars at proper separations of 30kpc<R_{perp}_<1Mpc. In contrast to measurements along the line-of-sight, regions transverse to quasars exhibit enhanced HI Ly{alpha} absorption and a larger variance than the ambient intergalactic medium, with increasing absorption and variance toward smaller scales. Analysis of composite spectra reveals excess absorption characterized by a Ly{alpha} equivalent width profile W=2.3{AA} (R_{perp}_/100kpc)^-0.46^. We also observe a high (=~60%) covering factor of strong, optically thick HI absorbers (HI column N_HI_>10^17.3^/cm2) at separations R_{perp}_<200kpc, which decreases to ~20% at R_{perp}_=~1Mpc, but still represents a significant excess over the cosmic average. This excess of optically thick absorption can be described by a quasar-absorber cross-correlation function {xi}_QA_(r)=(r/r_0_)^{gamma}^ with a large correlation length r_0_=12.5_-1.4_^+2.7^h^-1^Mpc (comoving) and {gamma}=1.68_-0.30_^+0.14^. The HI absorption measured around quasars exceeds that of any previously studied population, consistent with quasars being hosted by massive dark matter halos M_halo_{approx}10^12.5^M_{sun}_ at z~2.5. The environments of these massive halos are highly biased toward producing optically thick gas, and may even dominate the cosmic abundance of Lyman limit systems and hence the intergalactic opacity to ionizing photons at z~2.5. The anisotropic absorption around quasars implies the transverse direction is much less likely to be illuminated by ionizing radiation than the line-of-sight.
- ID:
- ivo://CDS.VizieR/J/ApJ/508/200
- Title:
- QSO low-z Ly{alpha} absorbers
- Short Name:
- J/ApJ/508/200
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To study the nature of low-z Ly{alpha} absorbers in the spectra of QSOs, we have obtained high signal-to-noise ratio (S/N) UV spectra of H1821+643 (z_em_=0.297) and PG 1116+215 (z_em_=0.177) with the Goddard High-Resolution Spectrograph on the Hubble Space Telescope.
- ID:
- ivo://CDS.VizieR/J/ApJS/194/45
- Title:
- QSO properties from SDSS-DR7
- Short Name:
- J/ApJS/194/45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a compilation of properties of the 105783 quasars in the Sloan Digital Sky Survey Data Release 7 (DR7) quasar catalog (Cat. VII/260). In this product, we compile continuum and emission line measurements around the H{alpha}, H{beta}, MgII, and CIV regions, as well as other quantities such as radio properties, and flags indicating broad absorption line quasars, disk emitters, etc. We also compile virial black hole mass estimates based on various calibrations. For the fiducial virial mass estimates we use the Vestergaard & Peterson (VP06; 2006ApJ...641..689V) calibrations for H{beta} and CIV, and our own calibration for MgII which matches the VP06 H{beta} masses on average. We describe the construction of this catalog and discuss its limitations.
595. QSOs CaII absorbers
- ID:
- ivo://CDS.VizieR/J/A+A/528/A12
- Title:
- QSOs CaII absorbers
- Short Name:
- J/A+A/528/A12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a systematic study of weak intervening CaII absorbers at low redshift (z<0.5), based on the analysis of archival high-resolution (R>=45000) optical spectra of 304 quasars and active galactic nuclei observed with VLT/UVES. Along a total redshift path of {DELTA}z~~100 we detected 23 intervening CaII absorbers in both the CaII H & K lines, with rest frame equivalent widths W_r,3934_=15-799m{AA} and column densities logN(CaII)=11.25-13.04 (obtained by fitting Voigt-profile components).
- ID:
- ivo://CDS.VizieR/J/MNRAS/400/1493
- Title:
- QSOs Lyman alpha emission line spectra
- Short Name:
- J/MNRAS/400/1493
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Arguably the best hope of understanding the tail end of the re-ionization of the intergalactic medium (IGM) at redshift z>6 is through the detection and characterization of the Gunn-Peterson damping wing absorption of the IGM in bright quasar spectra. However, the use of quasar spectra to measure the IGM damping wing requires a model of the quasar's intrinsic Lyman{alpha} emission line. Here we quantify the uncertainties in the intrinsic line shapes, and how those uncertainties affect the determination of the IGM neutral fraction. We have assembled a catalogue of high-resolution Hubble Space Telescope spectra of the emission lines of unobscured low-redshift quasars, and have characterized the variance in the shapes of their lines. We then add simulated absorption from the high-redshift IGM to these quasar spectra in order to determine the corresponding uncertainties in re-ionization constraints using current and future samples of z>6 quasar spectra. We find that, if the redshift of the Lyman{alpha} emission line is presumed to coincide with the systemic redshift determined from metal lines, the inferred IGM neutral fraction is systematically biased to low values due to a systematic blueshift of the Lyman{alpha} line relative to the metal lines.
- ID:
- ivo://CDS.VizieR/J/MNRAS/434/163
- Title:
- QSOs narrow absorption line variability
- Short Name:
- J/MNRAS/434/163
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results from a time domain study of absorption lines detected in quasar spectra with repeat observations from the Sloan Digital Sky Survey Data Release 7 (SDSS DR7). Beginning with over 4,500 unique time separation baselines of various absorption line species identified in the SDSS DR7 quasar spectra, we create a catalogue of 2,522 quasar absorption line (QAL) systems with two to eight repeat observations, representing the largest, unbiased, and homogeneous collection of multi-epoch absorption systems ever published. To investigate these systems for time-variability of narrow absorption lines, we refine this sample based on the reliability of the system detection, the proximity of pixels with bright sky contamination to individual absorption lines, and the quality of the continuum fit. Variability measurements of this sub-sample based on the absorption line equivalent widths yield a total of 33 systems with indications of significantly variable absorption strengths on time-scales ranging from one day to several years in the rest frame of the absorption system. Of these, at least 10 are from a class known as intervening absorption systems caused by foreground galaxies along the line of sight to the background quasar. This is the first evidence of possible absorption line variability detected in intervening systems, and their short time-scale variations suggest that small-scale structures (~10-100AU) are likely to exist in their host foreground galaxies.
- ID:
- ivo://CDS.VizieR/J/MNRAS/309/48
- Title:
- QSOs redshifts and spectra in ESO/SERC field 927
- Short Name:
- J/MNRAS/309/48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the spectra and redshifts of 62 quasars, from observations made with the Cerro Tololo Inter-American Observatory (CTIO) 4-m Blanco Telescope. These quasars form part of a total sample of 118 (with 56 having been published previously), which is being used for analysis of structure in the early universe. Quasars of particular interest are noted, including eight broad absorption line (BAL) quasars and two quasars with unusual emission spectra. Finally, we include a short summary of the present status of the large quasar group (LQG) that was discovered by Clowes & Campusano (1991, Cat. J/MNRAS/249/218 and 1994, Cat. J/MNRAS/266/317) from the earlier observations. The quasars are from an area ~25.3deg^2^ of ESO/SERC field 927, which is centred at (B1950) 10h 40m 00s, 05{deg} 00'00".
- ID:
- ivo://CDS.VizieR/J/ApJ/762/L19
- Title:
- Quasar pairs spectroscopy
- Short Name:
- J/ApJ/762/L19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The hosts of luminous z~2 quasars evolve into today's massive elliptical galaxies. Current theories predict that the circumgalactic medium (CGM) of these massive, dark matter halos (M_DM_~10^12.5^M_{sun}_) should be dominated by a T~10^7^K virialized plasma. We test this hypothesis with observations of 74 close-projected quasar pairs, using spectra of the background QSO to characterize the CGM of the foreground one. Surprisingly, our measurements reveal a cool (T~10^4^K), massive (M_CGM_>10^10^M_{sun}_), and metal-enriched (Z>~0.1Z_{sun}_) medium extending to at least the expected virial radius (r_vir_=160kpc). Furthermore, we conservatively estimate that the quasar CGM has a 64^+6^_-7_% covering fraction of optically thick gas (N_HI_>10^17.2^/cm^2^) within r_vir_; this covering factor is twice that of the contemporaneous Lyman break galaxy population. This unexpected reservoir of cool gas is rarely detected "down-the-barrel" to quasars, and hence it is likely that our background sight lines intercept gas that is shadowed from the quasar ionizing radiation by the same obscuring medium often invoked in models of active galactic nucleus unification. Because the high-z halos inhabited by quasars predate modern groups and clusters, these observations are also relevant to the formation and enrichment history of the intragroup/intracluster medium.
- ID:
- ivo://CDS.VizieR/J/MNRAS/266/317
- Title:
- Quasars in ESO/SERC field 927
- Short Name:
- J/MNRAS/266/317
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the spectroscopic observations of 56 quasars that were discovered by AQD (Automated Quasar Detection) in a field of ~25.3deg2, centred at (1950) RA l0h40m00s, Dec. 05deg00'00". These observations, with the CTIO 4-m telescope, led to the discovery by Clowes & Campusano of a large group of quasars with size ~100-200h^-1^Mpc at z~1.3. Quasars of particular interest are noted, including one that is a BAL quasar with z~1.78.
