We present the Voigt profile (VP) models, column densities, Doppler b parameters, kinematics, and distribution of components for 422 MgII absorbers found in a survey of 249 HIRES and UVES quasar spectra. The equivalent width range of the sample is 0.006 < W_r(2796) < 6.23 angstroms (A) and the redshift range is 0.19 < z < 2.55, with a mean of <z> = 1.18. Based on historical precedent, we classified 180 absorbers as weak systems (W_r(2796) < 0.3 A) and 242 as strong systems (W_r(2796) >= 0.3 A). Assuming a minimum number of significant components per system, the VP fitting, yielded a total of 2,989 components, with an average of 2.7 and 10.3 components found for the weak and strong MgII subsamples, respectively. The VP component line density for the full sample is 8.62 +/- 0.23 clouds/A. The distribution of VP component column density over the range 12.4 < log[N(MgII)] < 17.0 [ions cm^-2] is well modeled with a power-law slope of -1.45 +/- 0.01. The median Doppler b parameters are 4.5 +/- 3.5 km/s, 6.0 +/- 4.5 km/s and 5.7 +/- 4.4 km/s for the weak, strong, and full samples. We modeled the probability of component velocity splitting (the two-point velocity correlation function, TPCF) of our full sample using a three-component composite Gaussian function. Our resulting velocity dispersions are 25.4, 68.7, and 207.1 km/s, respectively. These data provide an excellent database for studying the cosmic evolution of MgII absorber kinematic evolution.
We present detailed measurements of the redshift path density, equivalent width distribution, column density distribution, and redshift evolution of ${\MgII}$ absorbers as measured in archival spectra from the UVES spectrograph at the Very Large Telescope (VLT/UVES) and the HIRES spectrograph at the Keck Telescope (Keck/HIRES) to equivalent width detection limits below $0.01$~Å. This survey examines 432 VLT/UVES spectra from the UVES SQUAD collaboration and 170 Keck/HIRES spectra from the KODIAQ group, allowing for detections of intervening ${\MgII}$ absorbers spanning redshifts $0.1 < z < 2.6…
We investigate the cool gas absorption in galaxy clusters by cross-correlating MgII absorbers detected in quasar spectra from Data Release 16 of the Sloan Digital Sky Survey (SDSS) with galaxy clusters identified in the Dark Energy Spectroscopic Instrument (DESI) survey. We find significant covering fractions ($1-5\, \%$ within $r_{500}$, depending on the chosen redshift interval), $\sim 4-5$ times higher than around random sightlines. While the covering fraction of cool gas in clusters decreases with increasing mass of the central galaxy, the total MgII mass within $r_{\rm 500}$ is nonetheles…
It is widely believed that the cool gas clouds traced by MgII absorption, within a velocity offset of 5000 km/s relative to the background quasar are mostly associated with the quasar itself, whereas the absorbers seen at larger velocity offsets towards us are intervening absorber systems and hence their existence is completely independent of the background quasar. Recent evidence by Bergeron et al. (2011, hereinafter BBM) has seriously questioned this paradigm, by showing that the number density of intervening MgII absorbers towards the 45 blazars in their sample is nearly 2 times the expecta…
Previous studies have shown that the incidence rate of intervening strong MgII absorbers towards GRBs were a factor of 2 - 4 higher than towards quasars. Exploring the similar sized and uniformly selected legacy data sets XQ-100 and XSGRB, each consisting of 100 quasar and 81 GRB afterglow spectra obtained with a single instrument (VLT/X-shooter), we demonstrate that there is no disagreement in the number density of strong MgII absorbers with rest-frame equivalent widths $W_r^{2796} >$ 1 Å towards GRBs and quasars in the redshift range 0.1 < z < 5. With large and similar sample sizes, and path…
We have searched for HI 21-cm absorption in 11 strong MgII systems ($W_{\rm r}$(MgII $λ2796$) $\ge 1$ Å) at $0.3<z<0.5$ using the Giant Metrewave Radio Telescope. We have detected HI 21-cm absorption in two of these. From the integrated optical depth ($\intτ~dv$) we estimate $N$(HI) = $43 \pm 2$ and $9 \pm 2$ in units of $10^{19}$ cm$^{-2}$ for the absorbers towards J1428+2103 ($z_{abs} = 0.3940$) and J1551+0713 ($z_{abs} = 0.3289$), respectively, assuming spin temperature, $T_s = 100$ K, and gas covering factor, $C_f = 1$. The velocity width of the HI absorption towards J1428+2103 and J1551+0…
The physical origin of the large-scale conformity in the colours and specific star formation rates of isolated low mass central galaxies and their neighbours on scales in excess of 1 Mpc is still under debate. One possible scenario is that gas is heated over large scales by feedback from active galactic nuclei (AGN), leading to coherent modulation of cooling and star formation between well-separated galaxies. In this Letter, the metal line absorption catalogue of Zhu & Menard (2013) is used to probe gas out to large projected radii around a sample of a million galaxies with stellar masses ~10^…
We use the latest version of the metal line absorption catalogue of Zhu & Ménard (2013) to study the clustering of MgII absorbers around massive galaxies (~10^11.5 M_sun), quasars and radio-loud AGN with redshifts between 0.4 and 0.75. Clustering is evaluated in two dimensions, by binning absorbers both in projected radius and in velocity separation. Excess MgII is detected around massive galaxies out to R_p=20 Mpc. At projected radii less than 800 kpc, the excess extends out to velocity separations of 10,000 km/s. The extent of the high velocity tail within this radius is independent of the m…
To study environmental effects on the circumgalactic medium (CGM), we use the samples of redMaPPer galaxy clusters, background quasars and cluster galaxies from the SDSS. With ~82 000 quasar spectra, we detect 197 MgII absorbers in and around the clusters. The detection rate per quasar is 2.7$\pm$0.7 times higher inside the clusters than outside the clusters, indicating that MgII absorbers are relatively abundant in clusters. However, when considering the galaxy number density, the absorber-to-galaxy ratio is rather low inside the clusters. If we assume that MgII absorbers are mainly contribut…
MgII absorbers induce reddening on background quasars. We measure this effect and infer the cosmic density of dust residing in these systems to be Ω ~ 2e-6, in units of the critical density of the Universe, which is comparable to the amount of dust found in galactic disks or about half the amount inferred to exist outside galaxies. We also estimate the neutral hydrogen abundance in MgII clouds to be Ω ~ 1.5e-4, which is approximately 5% of hydrogen in stars in galaxies. This implies a dust-to-gas mass ratio for MgII clouds of about 1/100, which is similar to the value for normal galaxies. This…
We present the results of a survey for intervening MgII absorbers in the redshift range z $\simeq$2-6 in the foreground of four high redshift quasar spectra, 5.79$\le z_{em}\le$6.133, obtained with the ESO VLT X-shooter. We identify 24 absorbers at $\ge 5σ$ significance in the equivalent width range 0.117$\le W_{2796}\le 3.655\unicode{xC5}$ with the highest redshift absorber at $z=4.89031\pm4\times10^{-5}$. For weak ($W_{2796}<0.3\unicode{xC5}$) systems, we measure an incidence rate $dN/dz$=1.35$\pm$0.58 at <z>=2.34 and find that it almost doubles to $dN/dz$=2.58$\pm$0.67 by <z>=4.81. Weak abs…
Observations at intermediate redshifts reveal the presence of numerous, compact, weak MgII absorbers with near to super-solar metallicities, often surrounded by more extended regions that produce CIV and/or OVI absorption in the circumgalactic medium at large impact parameters from luminous galaxies. Their origin and nature remains unclear. We hypothesize that undetected, satellite dwarf galaxies are responsible for producing some of these weak MgII absorbers. We test our hypothesis using gas dynamical simulations of galactic outflows from a dwarf satellite galaxy with a halo mass of $5\times1…
By comparing MgII absorption in the circumgalactic medium (CGM) of group environments to isolated galaxies, we investigated the impact of environment on the CGM. A MgII absorber is associated with a group if there are two or more galaxies at the absorption redshift within a projected distance of D=200 kpc from a background quasar and a line-of-sight velocity separation of 500 km/s. We compiled a sample of 29 group environments consisting of 74 galaxies (2-5 galaxies per group) at $0.113<z_{\rm gal}<0.888$. The group absorber median equivalent width ($\langle W_r(2796)\rangle=0.65\pm0.13$ Å) an…
We present joint constraints on the distribution of MgII absorption around galaxies, by combining the MgII absorption seen in stacked background galaxy spectra and the distribution of host galaxies of strong MgII systems from the spectra of background quasars. We present a suite of models that predict, the dependence of MgII absorption on a galaxy's apparent inclination, impact parameter(b) and azimuthal angle. The variations in the absorption strength with azimuthal angles provide much stronger constraints on the intrinsic geometry of the MgII absorption than the dependence on the galaxy's in…
The kinematics of MgII absorbers is the key to understanding the origin of cool, metal-enriched gas clouds in the circumgalactic medium of massive quiescent galaxies. Exploiting the fact that the cloud line-of-sight velocity distribution is the only unknown for predicting the redshift-space distortion~(RSD) of MgII absorbers from their 3D real-space distribution around galaxies, we develop a novel method to infer the cool cloud kinematics from the redshift-space galaxy-cloud cross-correlation $ξ^{s}$. We measure $ξ^{s}$ for ${\sim}10^4$ MgII absorbers around ${\sim}8{\times}10^5$ CMASS galaxie…
Using the SDSS spectra of quasars included in the DR7Q or DR12Q catalogs, we search for Mg II narrow absorption doublets in the spectra data around Mg II emission lines. We obtain 17,316 Mg II doublets, within the redshift range of 0.3299<= z_abs <= 2.5663. We find that a velocity offset of v_r < 6000 km/s is a safe boundary to constrain the vast majority of associated Mg II systems, although we find some doublets at v_r > 6000 km/s. If associated Mg II absorbers are defined by v_r < 6000 km/s, ~33.3% of the absorbers supposed to be contaminants of intervening systems. Removing the 33.3% conta…
We present the results of a systematic Giant Metrewave Radio Telescope (GMRT) survey of 21-cm absorption in a representative and unbiased sample of 35 strong MgII systems in the redshift range: zabs~1.10-1.45, 33 of which have W_r>1 Å. The survey using ~400hrs of telescope time has resulted in 9 new 21-cm detections and stringent 21-cm optical depth upper limits (median 3-sigma optical depth per 10 km/s of 0.017) for the remaining 26 systems. This is by far the largest number of 21-cm detections from any single survey of intervening absorbers. Prior to our survey no intervening 21-cm system wa…
Using the MEGAFLOW survey, which consists of a combination of MUSE and UVES observations of 22 quasar fields selected to contain strong MgII absorbers, we measure covering fractions of CIV and MgII as a function of impact parameter $b$ using a novel Bayesian logistic regression method on unbinned data, appropriate for small samples. We also analyse how the CIV and MgII covering fractions evolve with redshift. In the MUSE data, we found 215 $z=1-1.5$ [OII] emitters with fluxes $>10^{-17}$ erg\,s$^{-1}$\,cm$^{-2}$ and within 250 kpc of quasar sight-lines. Over this redshift path $z=1-1.5$, we ha…
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 2796, 2803 absorption from their circumgalactic medium within projected distances of 200 kpc from background quasars. In this work, we present "isolated" galaxies, which are defined as having no spectroscopically identified galaxy within a projected distance of 100 kpc and a line of sight velocity separation of 500 km/s. We standardized all galaxy properties to the Lambda CDM cosmology and galaxy luminosities, absolu…
Quasar-galaxy pairs at small separations are important probes of gas flows in the disk-halo interface in galaxies. We study host galaxies of 198 MgII absorbers at $0.39\le z_{abs}\le1.05$ that show detectable nebular emission lines in the SDSS spectra. We report measurements of impact parameter (5.9$\le D[kpc]\le$16.9) and absolute B-band magnitude ($-18.7\le {\rm M_B}\le -22.3$ mag) of host galaxies of 74 of these absorbers using multi-band images from the DESI Legacy Imaging Survey, more than doubling the number of known host galaxies with $D\le17$ kpc. This has allowed us to quantify the re…
We present an empirical connection between cold gas in galactic halos and star formation. Using a sample of more than 8,500 MgII absorbers from SDSS quasar spectra, we report the detection of a 15 sigma correlation between the rest equivalent width W0 of MgII absorbers and the associated OII luminosity, an estimator of star formation rate. This correlation has interesting implications: using only observable quantities we show that MgII absorbers trace a substantial fraction of the global OII luminosity density and recover the overall star formation history of the Universe derived from classica…
We estimate the abundance of dust in damped Lyman-α absorbers (DLAs) by statistically measuring the excess reddening they induce on their background quasars. We detect systematic reddening behind DLA consistent with the SMC type reddening curve, but it is inconsistent with the Milky Way type reddening. We find that the derived dust-to-gas ratio is, on average, inversely proportional to the column density of neutral hydrogen, implying that the amount of dust is constant, irrespective of the column density of hydrogen. It means that the average metallicity is inversely proportional to the column…
We performed multi-band deep imaging of the field around GRB 050730 to identify the host galaxies of intervening absorbers, which consist of a damped Lyα absorption (DLA) system at zabs=3.564, a sub-DLA system at zabs=3.022, and strong MgII absorption systems at zabs=1.773 and 2.253. Our observations were performed after the gamma-ray burst afterglow had disappeared. Thus, our imaging survey has a higher sensitivity to the host galaxies of the intervening absorbers than the normal imaging surveys in the direction of QSOs, for which the QSO glare tends to hide the foreground galaxies. In this d…
We use archival UV absorption-line data from HST/STIS to statistically analyse the absorption characteristics of the high-velocity clouds (HVCs) in the Galactic halo towards more than 40 extragalactic background sources. We determine absorption covering fractions of low- and intermediate ions (OI, CII, SiIII, MgII, FeII, SiIII, CIV, and SiIV) in the range fc = 0.20 - 0.70. For detailed analysis we concentrate on SiII absorption components in HVCs, for which we investigate the distribution of column densities, b-values, and radial velocities. Combining information for SiII and MgII, and using a…
We explore the distribution of cool (~$10^4$K) gas around galaxies and its dependence on galaxy properties. By cross-correlating about 50,000 MgII absorbers with millions of sources from the SDSS (optical), WISE (IR), and GALEX (UV) surveys we effectively extract about 2,000 galaxy-absorber pairs at z~0.5 and probe relations between absorption strength and galaxy type, impact parameter and azimuthal angle. We find that cool gas traced by MgII absorbers exists around both star-forming and passive galaxies with a similar incidence rate on scales greater than 100 kpc but each galaxy type exhibits…
We present a measurement of the cross-correlation of MgII absorption and massive galaxies, using the DR11 main galaxy sample of the Baryon Oscillation Spectroscopic Survey of SDSS-III (CMASS galaxies), and the DR7 quasar spectra of SDSS-II. The cross-correlation is measured by stacking quasar absorption spectra shifted to the redshift of galaxies that are within a certain impact parameter bin of the quasar, after dividing by a quasar continuum model. This results in an average MgII equivalent width as a function of impact parameter from a galaxy, ranging from 50 kpc to more than 10 Mpc in prop…
We study a sample of 17 z>1.5 absorbers selected based on the presence of strong CI absorption lines in SDSS spectra and observed with the ESO-VLT spectrograph X-shooter. We derive metallicities, depletion onto dust, and extinction by dust, and analyse the absorption from MgII, MgI, CaII and NaI that are redshifted into the near infrared wavelength range. We show that most of these CI absorbers have high metallicity and dust content. We detect nine CaII absorptions with $W$(CaII$λ$3934) >0.23 Åout of 14 systems where we have appropriate wavelength coverage. The observed equivalent widths are s…
Recent detailed studies of Narrow Absorption Line (NAL) systems in QSO-spectra have revealed that at least 50% of QSOs have NALs associated with the central engine, and in most cases they are found to be outflowing. Will studies of NALs provide the much sort after evidence for ubiquitous QSO feedback that can halt the formation of stars in galaxies? I present new results on the distribution of line-of-sight velocity offsets between MgII absorbers and their background QSOs, based on a large catalogue of absorbers from SDSS DR6 and greatly improved QSO-redshift estimates. My analysis reveals a h…
We present a neutral hydrogen-selected absorption-line survey of gas with HI column densities 15<log N(HI)<19 at z<1 using the Cosmic Origins Spectrograph on the Hubble Space Telescope. Our main aim is to determine the metallicity distribution of these absorbers. Our sample consists of 224 absorbers selected on the basis of their HI absorption strength. Here we discuss the properties of our survey and the immediate empirical results. We find singly and doubly ionized metal species and HI typically have similar velocity profiles, implying they probe gas in the same or similar environments. The …
Strong singly-ionized magnesium (MgII) absorption lines in quasar spectra typically serve as a proxy for intervening galaxies along the line of sight. Previous studies have found a correlation between the number of these MgII absorbers and the Faraday rotation measure (RM) at $\approx5$ GHz. We cross-match a sample of 35,752 optically-identified non-intrinsic MgII absorption systems with 25,649 polarized background radio sources for which we have measurements of both the spectral index and RM at 1.4 GHz. We use the spectral index to split the resulting sample of 599 sources into flat-spectrum …
Baryonic Ecosystem IN Galaxies (BEINGMgII) -- III. Cool gas reservoirs at $0.3 \le z \le 1.6$ in the Dark Energy Survey
Indian Institute of Astrophysics (IIA)（印度天体物理研究所）；Pondicherry University（本地治里大学）；Universitá degli Studi di Milano-Bicocca（米兰比可卡大学）；INAF - Osservatorio Astronomico di Trieste（意大利国家天体物理研究所的里雅斯特天文台）；Centre for Astrophysics and Supercomputing, Swinburne University of Technology（斯威本科技大学天体物理与超级计算中心）；INAF - Osservatorio Astronomico di Brera（意大利国家天体物理研究所布雷拉天文台）；European Southern Observatory（欧洲南方天文台）；Aix Marseille Université（艾克斯-马赛大学）；Kavli Institute for Astronomy and Astrophysics, Peking University（北京大学柯瓦利天文学与天体物理学研究所）
研究通过分析背景类星体光谱中检测到的中间冷却MgII吸收的起源，以及与之相关的星系在0.3 ≤ z ≤ 1.6红移范围内的性质，发现冷气体在星系晕中的演化和分布特征。
The XQ-100 survey provides optical and near infrared coverage of 36 blindly selected, intervening damped Lyman alpha systems (DLAs) at 2 < z < 4, simultaneously covering the MgII doublet at 2796A, 2803A, and the Ly-alpha transition. Using the XQ-100 DLA sample, we investigate the completeness of selecting DLA absorbers based on their MgII rest-frame equivalent width (W2796) at these redshifts. Of the 29 DLAs with clean MgII profiles, we find that six (20% of DLAs) have W2796 < 0.6A. The DLA incidence rate of W2796 < 0.6A absorbers is a factor of ~5 higher than what is seen in z~1 samples, indi…
We present final statistics from a survey for intervening MgII absorption towards 100 quasars with emission redshifts between $z=3.55$ and $z=7.08$. Using infrared spectra from Magellan/FIRE, we detect 279 cosmological MgII absorbers, and confirm that the incidence rate of $W_r>0.3 Å$ MgII absorption per comoving path length does not evolve measurably between $z=0.25$ and $z=7$. This is consistent with our detection of seven new MgII systems at $z>6$, a redshift range that was not covered in prior searches. Restricting to relatively strong MgII systems ($W_r>1$Å), there is significant evidence…
We find multiple Mg II absorption systems at redshift z=1.66, 2.069, and 2.097 in the spatially resolved spectra of the quadruply gravitationally lensed quasar H1413+1143 utilizing the Kyoto tridimensional spectrograph II (Kyoto 3DII) spectrograph on board the Subaru telescope. Here we present the first measurement of differences in Mg II absorption strength of the multiple intervening absorbers, which include ones identified as damped Lyman alpha (DLA) absorption systems. Our detection of the significant Mg II absorptions in the spatially resolved spectra reveals the inhomogeneous chemical en…
We introduce a Bayesian approach for modeling Voigt profiles in absorption spectroscopy and its implementation in the python package, BayesVP, publicly available at https://github.com/cameronliang/BayesVP. The code fits the absorption line profiles within specified wavelength ranges and generates posterior distributions for the column density, Doppler parameter, and redshifts of the corresponding absorbers. The code uses publicly available efficient parallel sampling packages to sample posterior and thus can be run on parallel platforms. BayesVP supports simultaneous fitting for multiple absor…
We present absorption variability results for 134 bona fide \mgii\ broad absorption line (BAL) quasars at 0.46~$\lesssim z \lesssim$~2.3 covering days to $\sim$ 10 yr in the rest frame. We use multiple-epoch spectra from the Sloan Digital Sky Survey, which has delivered the largest such BAL-variability sample ever studied. \mgii-BAL identifications and related measurements are compiled and presented in a catalog. We find a remarkable time-dependent asymmetry in EW variation from the sample, such that weakening troughs outnumber strengthening troughs, the first report of such a phenomenon in BA…
We investigate the extent and the properties of the MgII cool, low-density absorbing gas located in the halo and in the circum-galactic environment of quasars, using a sample of 31 projected quasar pairs with impact parameter pd<200kpc in the redshift range 0.5<z<1.6. In the transverse direction, we detect 18 MgII absorbers associated with the foreground quasars, while no absorption system originated by the gas surrounding the quasar itself is found along the line-of-sight. This suggests that the quasar emission induces an anisotropy in the absorbing gas distribution. Our observations indicate…
We present results from our search for HI 21-cm and OH 18-cm absorption at z~1-1.4 towards red quasars showing strong MgII absorption using uGMRT. The quasars J1501+1822 and J1521+5508 show multiple strong associated MgII absorption at z~1.1 and signature of reddening in their optical spectra. We report the detection of HI 21-cm absorption towards J1521+5508 at the systemic redshift of the quasar, with N(HI) =(1.2 +/- 0.2) x 10^{20} cm^{-2} for spin temperature of 100 K and unit covering factor. The HI 21-cm absorption is offset from the blueshifted strong MgII absorbers by >~1500 km/s. We do …
We argue that most strong intervening metal absorption line systems, where the rest equivalent width of the MgII 2796A line is >0.5A, are interstellar material in, and outflowing from, star-forming disks. We show that a version of the Kennicutt-Schmidt law is readily obtained if the MgII equivalent widths are interpreted as kinematic broadening from absorbing gas in outflowing winds originating from star-forming galaxies. Taking a phenomenological approach and using a set of observational constraints available for star-forming galaxies, we are able to account for the density distribution of st…
We report on the detection of a population of weak metal-line absorbers in the halo or nearby intergalactic environment of the Milky Way. Using high-resolution ultraviolet absorption-line spectra of bright QSOs obtained with the Space Telescope Imaging Spectrograph (STIS), along six sight lines we have observed unsaturated, narrow absorption in OI and SiII together with mildly saturated CII absorption at high radial velocities (|v_LSR|=100-320 km/s). The measured OI column densities are small, implying that these structures represent Lyman-Limit Systems and sub-Lyman-Limit System with HI colum…
Uncertainty-Aware Deep Learning for the Ly$α$ Forest: CNN-Based Absorber Detection and Characterization
Central University of Himachal Pradesh（喜马偕尔邦中央大学）；Indian Institute of Technology Tirupati（蒂鲁帕提印度理工学院）；Kapteyn Astronomical Institute, University of Groningen（格罗宁根大学卡普坦天文研究所）；Indian Institute of Technology Indore（印多尔印度理工学院）
We characterize the Ly$α$ halo and absorption systems toward PSO J083+11, a unique $z=6.3401$ weak-line quasar, using Gemini/GNIRS, Magellan/FIRE, and VLT/MUSE data. Strong absorptions by hydrogen and several metal lines (e.g., CII, MgII, and OI) are discovered in the spectrum, which indicates the presence of: (i) a proximate sub-damped Ly$α$ (sub-DLA) system at $z=6.314$ and (ii) a MgII absorber at $z=2.2305$. To describe the observed damping wing signal, we model the Ly$α$ absorption with a combination of a sub-DLA with the neutral hydrogen column density of $\log N_\mathrm{HI} = 20.03 \pm 0…
