- ID:
- ivo://CDS.VizieR/J/ApJ/862/22
- Title:
- CIV broad abs. line SDSS QSO obs. with Gemini
- Short Name:
- J/ApJ/862/22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We isolate a set of quasars that exhibit emergent CIV broad absorption lines (BALs) in their spectra by comparing spectra in the Sloan Digital Sky Survey (SDSS) Data Release 7 and the SDSS/BOSS Data Releases 9 and 10. After visually defining a set of emergent BALs, follow-up observations were obtained with the Gemini Observatory for 105 quasars. We find an emergence rate consistent with the previously reported disappearance rate of BAL quasars given the relative numbers of non-BAL and BAL quasars in the SDSS. We find that candidate newly emerged BALs are preferentially drawn from among BALs with smaller balnicity indices, shallower depths, larger velocities, and smaller widths. Within two rest-frame years (average) after a BAL has emerged, we find it equally likely to continue increasing in equivalent width in an observation 6 months later (average) as it is to start decreasing. From the time separations between our observations, we conclude that the coherence timescale of BALs is less than 100 rest-frame days. We observe coordinated variability among pairs of troughs in the same quasar, likely due to clouds at different velocities responding to the same changes in ionizing flux, and the coordination is stronger if the velocity separation between the two troughs is smaller. We speculate that the latter effect may be due to clouds having on average lower densities at higher velocities owing to mass conservation in an accelerating flow, causing the absorbing gas in those clouds to respond on different timescales to the same ionizing flux variations.
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Search Results
222. CIV candidates
- ID:
- ivo://CDS.VizieR/J/ApJ/708/868
- Title:
- CIV candidates
- Short Name:
- J/ApJ/708/868
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We surveyed the Hubble Space Telescope UV spectra of 49 low-redshift quasars for z<1 CIV candidates, relying solely on the characteristic wavelength separation of the doublet. After consideration of the defining traits of CIV doublets (e.g., consistent line profiles, other associated transitions, etc.), we defined a sample of 38 definite (group G=1) and five likely (G=2) doublets with rest equivalent widths W_r_ for both lines detected at >=3{sigma}_W_r__. We conducted Monte Carlo completeness tests to measure the unblocked redshift ({Delta}z) and co-moving path length ({Delta}X) over which we were sensitive to CIV doublets of a range of equivalent widths and column densities. Using the power-law model of f(N(C^+3^)), we measured the C^+3^ mass density relative to the critical density: {Omega}_C^+3^_=(6.20^+1.82^_-1.52_)x10^-8^ for 13<=logN(C^+3^)<=15.
- ID:
- ivo://CDS.VizieR/J/ApJS/239/23
- Title:
- CIV NAL systems from SDSS-DR14 quasar spectra
- Short Name:
- J/ApJS/239/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the quasar spectra from the Sloan Digital Sky Survey, all with two-epoch to six-epoch observations, we search for CIV{lambda}{lambda}1548,1551 narrow absorption doublets in spectral data from the blue wing {upsilon}r=30000km/s until the red wing of CIV{lambda}1549 emission lines. We have obtained 21239 CIV narrow absorption line (NAL) systems, of which 647 systems were significantly changed on timescales from {Delta}MJD=0.24 to 1842.38 days at rest-frame. Both samples of the C IV NAL systems with multi-epoch observations and the variable C IV NAL systems are the largest ones to date. The offset velocity distribution of the variable C IV NALs from quasars has a peak at {upsilon}r~2000km/s and gently extends to a larger offset velocity. There are 110 variable C IV NALs with {upsilon}r>12000km/s. In addition, about 10% intrinsic C IV NALs show time variability on a timescale of <2000 days. We find that the variations of C IV NALs are positively or negatively correlated with the alternations of quasar continua. The two kinds of correlations suggest that the variable C IV NALs included in our absorber catalog can be classified into at least two populations: (1) highly ionized systems that are dominated by highly ionized absorbing gas and negatively respond to the fluctuations of quasar emissions; and (2) lowly ionized systems that are dominated by lowly ionized absorbing gas and positively respond to fluctuations of quasar emissions. We also find that the absolute fractional changes in the absorption strengths of C IV NALs are inversely correlated with absorption strengths.
- ID:
- ivo://CDS.VizieR/J/ApJS/236/39
- Title:
- CIV narrow absorption line systems in SDSS-DR14
- Short Name:
- J/ApJS/236/39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We assemble 207 variable quasars from the Sloan Digital Sky Survey, all with at least 3 observations, to analyze CIV narrow absorption doublets, and obtain 328 CIV narrow absorption line systems. We find that 19 out of 328 CIV narrow absorption line systems were changed by |{Delta}W_r_^{lambda}1548^|>=3{sigma}_{Delta}Wr_^{lambda}1548^ on timescales from 15.9 to 1477 days at rest-frame. Among the 19 obviously variable CIV systems, we find that (1) 14 systems have relative velocities {upsilon}_r_>0.01c and 4 systems have {upsilon}_r_>0.1c, where c is the speed of light; (2) 13 systems are accompanied by other variable CIV systems; (3) 9 systems were changed continuously during multiple observations; and (4) 1 system with {upsilon}_r_=16862km/s was enhanced by {Delta}W_r_^{lambda}1548^=2.7{sigma}_{Delta}Wr_^{lambda}1548^ in 0.67 day at rest-frame. The variations of absorption lines are inversely correlated with the changes in the ionizing continuum. We also find that large variations of CIV narrow absorption lines are form differently over a short timescale.
- ID:
- ivo://CDS.VizieR/J/A+A/283/759
- Title:
- CIV QSO absorption systems
- Short Name:
- J/A+A/283/759
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High spectral resolution (FWHM = 0.6 or 0.35 {AA}) were obtained for six high redshift QSOs, z_em_ > 2.2, containing lines from 31 metal-rich absorption line systems amongst which 20 Civ doublets split in subcomponents with velocity differences within a system smaller than 400 km.s^-1^. Our survey has been combined with published data at similar resolution and the resulting sample comprises 35 systems, 23 of which are splitted in a total of 87 subcomponents. The mean redshift of the sample is <z> = 2.65. The observations were carried out at the F/8 Cassegrain focus of the 3.6m telescope at la Silla, between 1984 and 1989.
- ID:
- ivo://CDS.VizieR/J/ApJS/237/31
- Title:
- CLAMATO DR1: 3D Ly{alpha} forest tomography
- Short Name:
- J/ApJS/237/31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Faint star-forming galaxies at z~2-3 can be used as alternative background sources to probe the Ly{alpha} forest in addition to quasars, yielding high sightline densities that enable 3D tomographic reconstruction of the foreground absorption field. Here, we present the first data release from the COSMOS Ly{alpha} Mapping And Tomography Observations (CLAMATO) Survey, which was conducted with the LRIS spectrograph on the Keck I telescope. Over an observational footprint of 0.157deg^2^ within the COSMOS field, we used 240 galaxies and quasars at 2.17<z<3.00, with a mean comoving transverse separation of 2.37h^-1^Mpc, as background sources probing the foreground Ly{alpha} forest absorption at 2.05<z<2.55. The Ly{alpha} forest data was then used to create a Wiener-filtered tomographic reconstruction over a comoving volume of 3.15x10^5^h^-3^Mpc^3^ with an effective smoothing scale of 2.5h^-1^Mpc. In addition to traditional figures, this map is also presented as a virtual-reality visualization and manipulable interactive figure. We see large overdensities and underdensities that visually agree with the distribution of coeval galaxies from spectroscopic redshift surveys in the same field, including overdensities associated with several recently discovered galaxy protoclusters in the volume. Quantitatively, the map signal-to-noise is S/N^wiener^~3.4 over a 3h^-1^Mpc top-hat kernel based on the variances estimated from the Wiener filter. This data release includes the redshift catalog, reduced spectra, extracted Ly{alpha} forest pixel data, and reconstructed tomographic map of the absorption.
- ID:
- ivo://CDS.VizieR/J/ApJ/671/1503
- Title:
- Cl 0024+16 and MS 0451-03 spectrophotometry
- Short Name:
- J/ApJ/671/1503
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new results from our comparative survey of two massive, intermediate-redshift galaxy clusters, Cl 0024+17 (z=0.39) and MS 0451-03 (z=0.54). Combining optical and UV imaging with spectroscopy of member galaxies, we identify and study several key classes of "transition objects" whose stellar populations or dynamical states indicate a recent change in morphology and star formation rate. For the first time, we have been able to conclusively identify spiral galaxies in the process of transforming into S0 galaxies. This has been accomplished by locating both spirals whose star formation is being quenched and their eventual successors, the recently created S0s.
- ID:
- ivo://CDS.VizieR/J/ApJ/762/L30
- Title:
- CLASH: MCS J0416.1-2403 strong lensing analysis
- Short Name:
- J/ApJ/762/L30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We perform a strong lensing analysis of the merging galaxy cluster MACS J0416.1-2403 (M0416; z=0.42) in recent CLASH/HST observations. We identify 70 new multiple images and candidates of 23 background sources in the range 0.7<~z_phot_<~6.14 including two probable high-redshift dropouts, revealing a highly elongated lens with axis ratio =~5:1, and a major axis of ~100" (z_s_~2). Compared to other well-studied clusters, M0416 shows an enhanced lensing efficiency. Although the critical area is not particularly large (=~0.6{squ}'; z_s_~2), the number of multiple images, per critical area, is anomalously high. We calculate that the observed elongation boosts the number of multiple images, per critical area, by a factor of ~2.5x, due to the increased ratio of the caustic area relative to the critical area. Additionally, we find that the observed separation between the two main mass components enlarges the critical area by a factor of ~2. These geometrical effects can account for the high number (density) of multiple images observed. We find in numerical simulations that only ~4% of the clusters (with M_vir_>=6x10^14^h^-1^M_{sun}_) exhibit critical curves as elongated as in M0416.
- ID:
- ivo://CDS.VizieR/J/A+A/562/A86
- Title:
- CLASH. Photometric + photo-z catalog
- Short Name:
- J/A+A/562/A86
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Cluster Lensing And Supernovae survey with Hubble (CLASH) is a Hubble Space Telescope (HST) Multi-Cycle Treasury programme that observes 25 massive galaxy clusters, 20 of which were X-ray-selected to preferably choose dynamically relaxed clusters, and 5 additional "high magnification" clusters, which were selected based on their optical lensing properties. CLASH aims to study the dark matter distribution of the clusters and find magnified high-redshift galaxies behind them. CLASH observations were carried out in 16 bands from UV to NIR to derive accurate and reliable estimates of photometric redshifts. We present the CLASH photometric redshifts using 16 HST bands and study the photometric redshift accuracy including a detailed comparison between photometric and spectroscopic redshifts for the strong lensing arcs using the measurements from the cluster MACSJ1206.2-0847.
- ID:
- ivo://CDS.VizieR/J/ApJS/199/25
- Title:
- CLASH sources for MACS1149.6+2223
- Short Name:
- J/ApJS/199/25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Cluster Lensing And Supernova survey with Hubble (CLASH) is a 524-orbit Multi-Cycle Treasury Program to use the gravitational lensing properties of 25 galaxy clusters to accurately constrain their mass distributions. The survey, described in detail in this paper, will definitively establish the degree of concentration of dark matter in the cluster cores, a key prediction of structure formation models. The CLASH cluster sample is larger and less biased than current samples of space-based imaging studies of clusters to similar depth, as we have minimized lensing-based selection that favors systems with overly dense cores. Specifically, 20 CLASH clusters are solely X-ray selected. The X-ray-selected clusters are massive (kT>5keV) and, in most cases, dynamically relaxed. Five additional clusters are included for their lensing strength ({theta}_Ein_>35" at z_s_=2) to optimize the likelihood of finding highly magnified high-z (z>7) galaxies. A total of 16 broadband filters, spanning the near-UV to near-IR, are employed for each 20-orbit campaign on each cluster. These data are used to measure precise ({sigma}_z_~0.02(1+z)) photometric redshifts for newly discovered arcs. Observations of each cluster are spread over eight epochs to enable a search for Type Ia supernovae at z>1 to improve constraints on the time dependence of the dark energy equation of state and the evolution of supernovae. We present newly re-derived X-ray luminosities, temperatures, and Fe abundances for the CLASH clusters as well as a representative source list for MACS1149.6+2223 (z=0.544).
