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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…

天体物理学 · 物理学 2008-11-26 C. L. Carilli , Ran Wang , M. van Hoven , K. Dwarakanath , J. Chengalur , S. Wyithe

We report the GMRT detection of HI 21cm absorption from the $z \sim 3.39$ damped Lyman-$\alpha$ absorber (DLA) towards PKS 0201+113, the highest redshift at which 21cm absorption has been detected in a DLA. The absorption is spread over…

天体物理学 · 物理学 2008-11-26 N. Kanekar , J. N. Chengalur , W. M. Lane

We report the detection of \HI 21-cm absorption in the $z=0.96$ early-type lensing galaxy towards MG J0414+0534 with the Green Bank Telescope. The absorption, with total $N_{\rm HI}=1.6 \times 10^{18} (T_{\rm s}/f) {\rm cm}^{-2}$, is…

天体物理学 · 物理学 2009-11-13 S. J. Curran , J. Darling , A. D. Bolatto , M. T. Whiting , C. Bignell , J. K. Webb

We report the detection of redshifted HI~21cm absorption in the $z \sim 2.347$ damped Lyman-$\alpha$ absorber (DLA) towards PKS B0438-436, with the Green Bank Telescope. This is the second-highest redshift at which 21cm absorption has been…

天体物理学 · 物理学 2009-11-11 N. Kanekar , R. Subrahmanyan , S. L. Ellison , W. M. Lane , J. N. Chengalur

We report a deep Giant Metrewave Radio Telescope (GMRT) search for Galactic H{\sc i} 21cm absorption towards the quasar B0438$-$436, yielding the detection of wide, weak H{\sc i} 21cm absorption, with a velocity-integrated H{\sc i} 21cm…

We have detected HI 21cm line absorption by the Warm Neutral Medium (WNM) using the Westerbork Synthesis Radio Telescope. The absorption was detected toward Cygnus A at LSR velocities of -40 and -70 km s^{-1}. These two velocity ranges were…

天体物理学 · 物理学 2009-10-30 C. L. Carilli , K. S. Dwarakanath , W. M. Goss

We have carried out deep, high velocity resolution, interferometric Galactic HI 21 cm absorption spectroscopy towards 32 compact extra-galactic radio sources with the Giant Metrewave Radio Telescope (GMRT) and the Westerbork Synthesis Radio…

星系天体物理 · 物理学 2014-07-30 Nirupam Roy , Nissim Kanekar , Robert Braun , Jayaram N. Chengalur

We have carried out a sensitive high-latitude (|b| > 15deg.) HI 21cm-line absorption survey towards 102 sources using the GMRT. With a 3-sigma detection limit in optical depth of ~0.01, this is the most sensitive HI absorption survey. We…

天体物理学 · 物理学 2009-11-10 Rekhesh Mohan , K. S. Dwarakanath , G. Srinivasan

We report the detection of a deep broad HI 21 cm absorption system at z = 0.78 toward the radio source [HB89] 2351+456 (4C+45.51) at z = 1.992. The HI absorption was identified in a blind spectral line survey conducted at the Green Bank…

We have searched for HI 21-cm absorption in 11 strong MgII systems ($W_{\rm r}$(MgII $\lambda 2796$) $\ge 1$ \AA) 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…

星系天体物理 · 物理学 2017-04-12 Rajeshwari Dutta , Raghunathan Srianand , Neeraj Gupta , Ravi Joshi

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…

星系天体物理 · 物理学 2017-01-11 J. N. H. S. Aditya , Nissim Kanekar , J. Xavier Prochaska , Brandon Day , Paul Lynam , Jocelyn Cruz

We detect the 21 cm line of neutral hydrogen in absorption at a redshift of 0.673 towards the 1 Jy radio source 1504+377. The 1504+377 radio source is located toward the center of what appears to be an inclined disk galaxy at z = 0.674. The…

天体物理学 · 物理学 2009-10-28 C. L. Carilli , Karl M. Menten , Mark J. Reid , M. P. Rupen

We have searched for redshifted absorption in the 21 cm line of neutral hydrogen toward `red quasars', which are extragalactic radio sources with a steep spectral drop between optical and infrared wavelengths. The success rate for detecting…

天体物理学 · 物理学 2007-05-23 C. L. Carilli , Karl M. Menten , C. P. Moore

We report results from a deep search for redshifted HI 21cm absorption in 55 strong MgII$\lambda$2796 absorbers (having $W (MgII) > 0.5 \AA$) at intermediate redshifts, $0.58 < z_{\rm abs} < 1.70$, with the Green Bank Telescope (GBT) and…

宇宙学与河外天体物理 · 物理学 2015-05-13 N. Kanekar , J. X. Prochaska , S. L. Ellison , J. N. Chengalur

We report conclusive verification of the detection of associated HI 21 cm absorption in the early-type host galaxy of the compact radio source PMNJ2054-4242. We estimate an effective spectral line velocity width of 418 +/- 20 km s^{-1} and…

宇宙学与河外天体物理 · 物理学 2015-06-12 J. R. Allison , S. J. Curran , E. M. Sadler , S. N. Reeves

We present the results from our search for HI 21-cm absorption in a sample of 16 strong FeII systems ($W_{\rm r}$(MgII $\lambda2796$) $\ge1.0$ \AA\ and $W_{\rm r}$(FeII $\lambda2600$) or $W_{\rm FeII}$ $\ge1$ \AA) at $0.5<z<1.5$ using the…

星系天体物理 · 物理学 2017-01-11 R. Dutta , R. Srianand , N. Gupta , R. Joshi , P. Petitjean , P. Noterdaeme , J. Ge , J. -K. Krogager

We report the discovery of two remarkable high-opacity HI 21cm absorbers against low-luminosity active galactic nuclei (AGNs), at $z = 1.2166$ towards J0229+0044 and at $z=1.1630$ towards J0229+0053. The absorbers were detected in an…

星系天体物理 · 物理学 2020-08-27 Aditya Chowdhury , Nissim Kanekar , Jayaram Chengalur

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…

星系天体物理 · 物理学 2020-01-08 Rajeshwari Dutta , Raghunathan Srianand , Neeraj Gupta , Ravi Joshi

We present an overview of the occurrence and properties of atomic gas associated with compact radio sources at redshifts up to z=0.85. Searches for HI 21cm absorption were made with the Westerbork Synthesis Radio Telescope at UHF-high…

We report on WSRT observations of HI and OH absorption at z=0.885 towards the radio lens PKS 1830-21, mm wave transitions of several molecular species have already been observed at this redshift. At mm wavelengths the source structure is…

天体物理学 · 物理学 2011-05-23 Jayaram N. Chengalur , A. G. de Bruyn , D. Narasimha
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