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We present the results of a search for associated 21 cm HI absorption at redshift 0.42 < z < 1.00 in radio-loud galaxies from three Galaxy And Mass Assembly (GAMA) survey fields. These observations were carried out as part of a pilot survey…

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

We present an HI 21cm absorption study of a sample of 26 radio-loud active galactic nuclei (AGN) at $0.25 < z < 0.4$ carried out with the Karl G. Jansky Very Large Array. Our aim was to study the rate of incidence of HI in various classes…

Astrophysics of Galaxies · Physics 2021-10-20 Suma Murthy , Raffaella Morganti , Tom Oosterloo , Filippo M. Maccagni

Recent targeted studies of associated HI absorption in radio galaxies are starting to map out the location, and potential cosmological evolution, of the cold gas in the host galaxies of Active Galactic Nuclei (AGN). The observed 21 cm…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 J. R. Allison , E. M. Sadler , S. J. Curran , S. N. Reeves

We present results from a search for the HI 21-cm line in absorption towards 16 bright radio sources with the 6-antenna commissioning array of the Australian Square Kilometre Array Pathfinder (ASKAP). Our targets were selected from the 2-Jy…

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 conducted a HI 21cm absorption study of a sample of 147 nearby (z < 0.1) low-power radio sources with $10\,\mathrm{mJy} < S_{1.4\,\mathrm{GHz}} < 30\,\mathrm{mJy}$ and $\log(P_{1.4\,\mathrm{GHz}}/\mathrm{W\,Hz^{-1}}) = 20.5-23.7$, using…

Astrophysics of Galaxies · Physics 2026-03-06 Yang Su , Qingzheng Yu , Taotao Fang , Junfeng Wang , Jianfeng Wu , Bo Zhang

Many radio galaxies show the presence of dense and dusty gas near the active nucleus. This can be traced by both 21cm HI absorption and soft X-ray absorption, offering new insight into the physical nature of the circumnuclear medium of…

We present an analysis of the HI absorption in a sample of 101 flux-selected radio AGN (S_1.4 GHz > 50 mJy) observed with the Westerbork Synthesis Radio Telescope (WSRT). HI absorption is detected in 32 galaxies, showing a broad variety of…

Astrophysics of Galaxies · Physics 2015-06-23 K. Gereb , F. M. Maccagni , R. Morganti , T. A. Oosterloo

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

From a survey for redshifted HI 21-cm and OH 18-cm absorption in the hosts of a sample of radio galaxies and quasars, we detect HI in three of the ten and OH in none of the fourteen sources for which useful data were obtained. As expected…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 S. J. Curran , M. T. Whiting , M. T. Murphy , J. K. Webb , C. Bignell , A. G. Polatidis , T. Wiklind , P. Francis , G. Langston

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 present results from a search of cold neutral gas associated with radio-loud active galactic nuclei (AGNs) at $z < 0.5$ using HI 21-cm absorption measurements from the MeerKAT Absorption Line Survey (MALS). Cross-matching the MALS 1006…

Astrophysics of Galaxies · Physics 2026-04-23 P. P. Deka , N. Gupta , J-. K. Krogager , S. A. Balashev , H. -W. Chen , F. Combes , H. -R. Klöckner , P. Noterdaeme

We report the discovery of a new 21-cm HI absorption system using commissioning data from the Boolardy Engineering Test Array of the Australian Square Kilometre Array Pathfinder (ASKAP). Using the 711.5 - 1015.5 MHz band of ASKAP we were…

We present the results of HI and OH absorption measurements towards a sample of radio sources using the Arecibo 305-m telescope and the GMRT. In total, 27 radio sources were searched for associated 21-cm HI absorption. One totally new HI…

Astrophysics · Physics 2009-11-11 Neeraj Gupta , C. J. Salter , D. J. Saikia , T. Ghosh , S. Jeyakumar

We have selected a sample of 80 candidates for obscured radio-loud active galactic nuclei and presented their basic optical/near-infrared (NIR) properties in Paper 1. In this paper, we present both high-resolution radio continuum images for…

Astrophysics of Galaxies · Physics 2016-03-16 Ting Yan , John T. Stocke , Jeremy Darling , Emmanuel Momjian , Soniya Sharma , Nissim Kanekar

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 a search for associated HI 21 cm absorption in a sample of 29 radio-loud active galactic nuclei (AGNs) at $0.7 < z < 1$, carried out with the upgraded Giant Metrewave Radio Telescope. We detect HI 21 cm absorption against none of…

Astrophysics of Galaxies · Physics 2022-03-30 Suma Murthy , Raffaella Morganti , Nissim Kanekar , Tom Oosterloo

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

We present a pilot study of extragalactic HI 21-cm absorption lines using the Five-hundred-meter Aperture Spherical radio Telescope (FAST). We observed 5 continuum sources with HI absorption features firstly identified in the 40% data…

Astrophysics of Galaxies · Physics 2021-03-31 Bo Zhang , Ming Zhu , Zhong-Zu Wu , Qing-Zheng Yu , Peng Jiang , You-Ling Yue , Meng-Lin Huang , Qiao-Li Hao
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