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We present the results of a large search for intrinsic HI 21 cm and OH 18 cm absorption in 145 compact radio sources in the redshift range 0.02< z <3.8 with the Green Bank Telescope. We re-detect HI 21 cm absorption toward six known…

Astrophysics of Galaxies · Physics 2019-11-27 Kathryn Grasha , Jeremy Darling , Alberto Bolatto , Adam K. Leroy , John T. Stocke

We present the early science results from a blind search of the extragalactic HI 21-cm absorption lines at z $\leqslant$ 0.09 with the drift-scan observation of the Five-hundred-meter Aperture Spherical radio Telescope (FAST). We carried…

We present results from a search for 21 cm associated HI absorption in a sample of 29 radio sources selected from the Australia Telescope 20 GHz survey. Observations were conducted using the Australia Telescope Compact Array Broadband…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 J. R. Allison , S. J. Curran , B. H. C. Emonts , K. Gareb , E. K. Mahony , S. Reeves , E. M. Sadler , A. Tanna , M. T. Whiting , M. A. Zwaan

WSRT observations have provided a first inventory of the incidence of HI 21 cm line absorption associated with AGN at redshifts up to z=1.0. There is a large range in line depths, from tau=0.44 to tau less than 0.001, and a substantial…

Astrophysics · Physics 2007-05-23 R. C. Vermeulen

We report the discovery of three HI absorbers toward low-power radio active galactic nuclei (AGNs) in a pilot HI absorption survey with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). Compared to past studies, FAST…

Astrophysics of Galaxies · Physics 2023-08-04 Qingzheng Yu , Taotao Fang , Junfeng Wang , Jianfeng Wu

Using the recently completed Giant Meterwave Radio Telescope, we have detected the HI 21 cm-line absorption from the peculiar galaxy C153 in the galaxy cluster Abell 2125. The HI absorption is at a redshift of 0.2533, with a peak optical…

Astrophysics · Physics 2009-11-06 K. S. Dwarakanath , F. N. Owen

We present and discuss European VLBI Network UHF band spectral line observations, made to localise the redshifted 21cm HI absorption known to occur in the subgalactic sized compact steep spectrum galaxies 3C 49 and 3C 268.3. We have…

Astrophysics · Physics 2009-11-11 A. Labiano , R. C. Vermeulen , P. D. Barthel , C. P. O'Dea , J. F. Gallimore , S. Baum , W. de Vries

Neutral atomic hydrogen and molecular gas in the host galaxies of radio active galactic nuclei (AGN) can be traced using H I 21-cm and OH-1667 MHz absorption lines to understand the fueling and feedback processes. We present the results of…

Astrophysics of Galaxies · Physics 2024-07-01 Yogesh Chandola , D. J. Saikia , Yin-Zhe Ma , Zheng Zheng , Chao-Wei Tsai , Di Li , Denis Tramonte , Hengxing Pan

A search for HI absorption has been made in 23 radio galaxies using the ATCA, the VLA and the WSRT. In five galaxies HI absorption was detected. We investigate how the detection rate is distributed among galaxies with different radio and…

Astrophysics · Physics 2009-10-31 R. Morganti , T. A. Oosterloo , C. N. Tadhunter , G. van Moorsel , N. Killeen , K. A. Wills

We present Giant Metrewave Radio Telescope (GMRT) observations of redshifted 21-cm absorption from the $z=0.437$ metal line absorption system towards PKS 1243-072. HI absorption is clearly detected; the absorption profile has a velocity…

Astrophysics · Physics 2009-11-07 Nissim Kanekar , Ramana M. Athreya , Jayaram N. Chengalur

We present the results of a blind search for intervening HI 21 cm absorption toward 260 radio sources in the redshift range 0<z<2.74 with the Green Bank Telescope. The survey has the sensitivity to detect sub-damped Lyman-alpha (DLA)…

Astrophysics of Galaxies · Physics 2020-08-25 Kathryn Grasha , Jeremy Darling , Adam K. Leroy , Alberto D. Bolatto

We report results from a Giant Metrewave Radio Telescope search for "associated" redshifted HI 21cm absorption from 24 active galactic nuclei (AGNs), at $1.1 < z < 3.6$, selected from the Caltech-Jodrell Bank Flat-spectrum (CJF) sample. 22…

Astrophysics of Galaxies · Physics 2015-12-09 J. N. H. S. Aditya , Nissim Kanekar , Sushma Kurapati

We present the results of a survey for intervening HI 21-cm absorbers at intermediate and low redshift (0<z<1.2). For our total sample of 24 systems, we obtained high quality data for 17 systems, the other seven being severely affected by…

Astrophysics of Galaxies · Physics 2015-09-09 M. A. Zwaan , J. Liske , C. Péroux , M. T. Murphy , N. Bouché , S. J. Curran , A. D. Biggs

HI absorption studies yield information on both AGN feeding and feedback processes. This AGN activity interacts with the neutral gas in compact radio sources, which are believed to represent the young or recently re-triggered AGN…

Astrophysics of Galaxies · Physics 2017-02-01 M. Glowacki , J. R. Allison , E. M. Sadler , V. A. Moss , S. J. Curran , A. Musaeva , C. Deng , R. Parry , M. C. Sligo

We have searched for HI 21cm absorption toward the two brightest radio AGN at high redshift, J0924--2201 at $z = 5.20$, and J0913+5919 at $z=5.11$, using the Giant Meter Wave Radio Telescope (GMRT). These data set a 3$\sigma$ upper limit to…

Astrophysics · Physics 2008-11-26 C. L. Carilli , Ran Wang , M. van Hoven , K. Dwarakanath , J. Chengalur , S. Wyithe

We present an HI absorption survey of the central 250 pc of the Galaxy. Very Large Array (VLA) observations were made at 21 cm in the DnC and CnB configurations and have a resolution of ~15"(0.6 pc at the Galactic Center (GC) distance) and…

Astrophysics of Galaxies · Physics 2015-05-20 Cornelia C. Lang , W. Miller Goss , Claudia Cyganowski , Kelsey I. Clubb

We report the first detections of associated H{\sc i} 21\,cm absorption in Gigahertz-peaked-spectrum (GPS) sources at high redshifts, $z > 1$, using the Giant Metrewave Radio Telescope (GMRT). Our GMRT search for associated H{\sc i} 21\,cm…

Astrophysics of Galaxies · Physics 2017-10-25 J. N. H. S. Aditya , Nissim Kanekar

We report the first $5\sigma$ detection of HI 21 cm emission from a star-forming galaxy at redshift $z\sim1.3$ (nearly 9 billion years ago) using upgraded Giant Metrewave Radio Telescope (uGMRT). This is the highest redshift HI detection in…

Astrophysics of Galaxies · Physics 2023-01-25 Arnab Chakraborty , Nirupam Roy

We have used the 610 MHz receivers of the Giant Metrewave Radio Telescope (GMRT) to detect associated HI 21cm absorption from the $z = 1.2230$ blazar TXS1954+513. The GMRT HI 21cm absorption is likely to arise against either the…

Astrophysics of Galaxies · Physics 2017-01-11 J. N. H. S. Aditya , Nissim Kanekar , J. Xavier Prochaska , Brandon Day , Paul Lynam , Jocelyn Cruz

We present early science results from the First Large Absorption Survey in HI (FLASH), a spectroscopically blind survey for 21-cm absorption lines in cold hydrogen HI gas at cosmological distances using the Australian Square Kilometre Array…