HI 21-cm absorption from $z\sim 0.35$ strong MgII absorbers

Abstract

We have searched for HI 21-cm absorption in 11 strong MgII systems ($W_{\mathrm{r}}$(MgII $\lambda 2796$) $\ge 1$ 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 ($\int \tau dv$) 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+0713 indicate that the gas temperature is $<1600$ K and $<350$ K, respectively. The $3\sigma$ upper limits on $\int \tau dv$ in case of the HI 21-cm non-detections indicate that these MgII absorbers are likely to arise from sub-damped Lyman-$\alpha$ systems, when we assume $T_s=100$ K and $C_f=1$. This is verified for one of the systems which has $N$(HI) measurement using Lyman-$\alpha$ absorption detected in the ultraviolet spectrum. We estimate the detection rate of HI 21-cm absorption in strong MgII systems in our sample to be $0.18_{-0.12}^{+0.24}$ at $z\sim 0.35$, for an integrated optical depth sensitivity of $\le 0.3$ km s${}^{-1}$. Comparing with the results of HI 21-cm absorption surveys in strong MgII systems at higher redshifts from the literature, we do not find any significant evolution in the incidence and number density per unit redshift of HI 21-cm absorbers in strong MgII systems over $0.3<z<1.5$.

9 pages, 4 figures, 4 tables, accepted in MNRAS. arXiv admin note: text overlap with arXiv:1611.07034

References in corpus (17)

• Cosmic Star Formation History
• The Eleventh and Twelfth Data Releases of the Sloan Digital Sky Survey: Final Data from SDSS-III
• Molecular hydrogen in high-redshift Damped Lyman-alpha systems: The VLT/UVES database
• The HI Content of the Universe over the Past 10 Gyrs
• Detection of the 2175Å~ extinction feature and 21-cm absorption in two MgII systems at z~1.3
• An HST/COS survey of molecular hydrogen in DLAs & sub-DLAs at z < 1: Molecular fraction and excitation temperature
• HI 21-cm absorption survey of quasar-galaxy pairs: Distribution of cold gas around z<0.4 galaxies
• HI emission and absorption in nearby, gas-rich galaxies II. -- sample completion and detection of intervening absorption in NGC 5156
• New HI 21-cm absorbers at low and intermediate redshifts
• A GBT Survey for HI 21 cm Absorption in the Disks and Halos of Low-Redshift Galaxies
• A correlation between the HI 21-cm absorption strength and impact parameter in external galaxies
• Mapping kiloparsec-scale structures in the extended HI disc of the galaxy UGC 00439 by HI 21-cm absorption
• HI emission and absorption in nearby, gas-rich galaxies
• Detecting cold gas at intermediate redshifts: GMRT survey using Mg II systems
• Incidence of HI 21-cm absorption in strong FeII systems at $0.5<z<1.5$
• Distribution of Cold ($\lesssim 300$K) Atomic Gas in Galaxies: Results from the GBT HI Absorption Survey Probing the Inner Halos ($\rho <20$kpc) of Low-z Galaxies
• Cold parsec-scale gas in a zabs~0.1 sub-DLA with disparate H2 and 21-cm absorption

Cited by in corpus (12)

• A Giant Arc on the Sky
• COS-Weak: Probing the CGM using analogs of weak Mg II absorbers at z < 0.3
• Blind HI and OH absorption line search: first results with MALS and uGMRT processed using ARTIP
• Revealing HI gas in emission and absorption on pc to kpc scales in a galaxy at z ~ 0.017
• Evolution of cold gas at 2<z<5: a blind search for HI and OH absorption lines towards mid-infrared color selected radio-loud AGNs
• uGMRT search for cold gas at z~1-1.4 towards red quasars
• Probing galaxy evolution through HI 21-cm emission and absorption: current status and prospects with the Square Kilometre Array
• Intervening or associated? Machine learning classification of redshifted H I 21-cm absorption
• The potential of tracing the star formation history with HI 21-cm in intervening absorption systems
• Cold neutral hydrogen gas in galaxies
• Physical conditions and redshift evolution of optically thin C III absorbers: Low-z sample
• HI 21-cm Absorption Associated with Foreground Galaxies on Top of Quasars