Giant Metrewave Radio Telescope detection of associated H i 21-cm absorption at<i>z</i> = 1.2230 towards TXS 1954+513

Aditya, J. N. H. S.; Kanekar, Nissim; Prochaska, J. Xavier; Day, Brandon; Lynam, P.; Cruz, Jocelyn

doi:10.1093/mnras/stw3105

Cited by 26 publications

(32 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…If we include the forthcoming results of Grasha et al (2017) 9 , this increases to 6.67σ. Aditya et al (2017) have recently detected H I 21-cm absorption at z = 1.223 in TXS 1954+513, which they claim has an ultra-violet luminosity of LUV = 4 ± 1 × 10 23 W Hz −1 , following the method of Curran et al (2008). The luminosity is, however, based upon only two photometry measurements which are in the rest-frame optical band and extrapolated to the UV.…”

Section: Observational Resultsmentioning

confidence: 99%

“…3), which is used as the FWHM to obtain the integrated optical depth limit, thus giving the N H I f /T spin limit per channel (see Curran 2012). Allison et al (2012Allison et al ( , 2015; Yan et al (2012Yan et al ( , 2016; Geréb et al (2015); Srianand et al (2015); Aditya et al (2016Aditya et al ( , 2017. 8 The absorption redshift of z abs = 1.343 (Kanekar et al 2009) corresponds to a velocity offset of ∆v = 64 km s −1 relative to z QSO = 1.3425 and so we deem this as associated rather than intervening.…”

Section: Emission Feature In 0114+074mentioning

confidence: 99%

See 1 more Smart Citation

Atomic and molecular absorption in redshifted radio sources

Curran

Whiting

Allison

et al. 2017

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We report on a survey for associated H I 21-cm and OH 18-cm absorption with the Giant Metrewave Radio Telescope at redshifts z ≈ 0.2 − 0.4. Although the low redshift selection ensures that our targets are below the critical ultra-violet luminosity (L UV ∼ 10 23 W Hz −1 ), which is hypothesised to ionise all of the neutral gas in the host galaxy, we do not obtain any detections in the six sources searched. Analysing these in context of the previous surveys, in addition to the anti-correlation with the ultra-violet luminosity (ionising photon rate), we find a correlation between the strength of the absorption and the blue -near-infrared colour, as well as the radio-band turnover frequency. We believe that these are due to the photo-ionisation of the neutral gas, an obscured sight-line being more conducive to the presence of cold gas and the compact radio emission being better intercepted by the absorbing gas, maximising the flux coverage, respectively. Regarding the photo-ionisation, the compilation of the previous surveys increases the significance of the critical ionising photon rate, above which all of the gas in the host galaxy is hypothesised to be ionised (Q H I ≈ 3 × 10 56 sec −1 ), to > 5σ. This reaffirms that this is an ubiquitous effect, which has profound implications for the detection of neutral gas in these objects with the Square Kilometre Array.

show abstract

Section: Observational Resultsmentioning

confidence: 99%

Section: Emission Feature In 0114+074mentioning

confidence: 99%

Atomic and molecular absorption in redshifted radio sources

Curran

Whiting

Allison

et al. 2017

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

show abstract

“…Published studies have mostly used the GMRT and the GBT. In contrast to the over 150 detections at z ≤ 1, there are only 7 detections of associated H I 21-cm absorption above this redshift (Ishwara-Chandra et al 2003;Curran et al 2013c;Aditya et al 2017Aditya et al , 2018 and only two of those are at z > 2 (one of which is even a tentative detection; Uson et al 1991;Aditya et al 2016).…”

Section: Evolution With Redshift Effect Of Uv Radiationmentioning

confidence: 67%

“…The significance (or not) of the trend relies on a tentative detection found at redshift 3.53. In the study of GPS of Aditya et al (2017), no trend is found when they compare the detection rate with similar studies at low redshift. The final word is likely to come from the new surveys that will be done with the SKA pathfinders (see §9).…”

Section: Evolution With Redshift Effect Of Uv Radiationmentioning

confidence: 89%

“…However, the presence of a fast outflow (with velocities exceeding 1000 km s −1 ) is traced by the ionised gas (Holt et al 2006) and, more recently, by the molecular Gallimore et al (1994) gas observed with ALMA (Oosterloo et al in prep). Interesting is also the case of, although not extremely broad (< 100 km s −1 ), H I absorption blueshifted by about 300 km s −1 , observed in a blazar object (TXS 1954+513, (Aditya et al 2017)), likely the result of a recent realignment of the jet axis possibly connected with restarting activity.…”

Section: Irregular H I Structuresmentioning

confidence: 99%

See 1 more Smart Citation

The interstellar and circumnuclear medium of active nuclei traced by H i 21 cm absorption

Morganti

Oosterloo

2018

Astron Astrophys Rev

View full text Add to dashboard Cite

This review summarises what we have learnt in the last two decades based on H I 21-cm absorption observations about the cold interstellar medium (ISM) in the central regions of active galaxies and about the interplay between this gas and the active nucleus (AGN). H I absorption is a powerful tracer on all scales, from the parsec-scales close to the central black hole to structures of many tens of kpc tracing interactions and mergers of galaxies. Given the strong radio continuum emission often associated with the central activity, H I absorption observations can be used to study the H I near an active nucleus out to much higher redshifts than is possible by using H I emission. In this way, H I absorption has been used to characterise in detail the general ISM in active galaxies, to trace the fuelling of radio-loud AGN, to study the feedback occurring between the energy released by the active nucleus and the ISM, and the impact of such interactions on the evolution of galaxies and of their AGN. In the last two decades, significant progress has been made in all these areas. It is now well established that many radio loud AGN are surrounded by small, regularly rotating gas disks that contain a significant fraction of H I. The structure of these disks has been traced down to parsec scales by VLBI observations. Some groups of objects, and in particular young and recently restarted radio galaxies, appear to have a particularly high detection rate of H I. This is interesting in connection with the evolution of these AGN and their impact on the surrounding ISM. This is further confirmed by an important discovery, made thanks to technical upgrades of radio telescopes, namely the presence of fast, AGN-driven outflows of cold gas which give a direct view of the impact of the energy released by AGN on the evolution of galaxies (AGN feedback). In addition, evidence has been collected that clouds of cold gas can play a role in fuelling the nuclear activity. This review ends by briefly describing the upcoming large, blind H I absorption surveys planned for the new radio telescopes which will soon become operational. These surveys will allow to significantly expand existing work, but will also allow to explore new topics, in particular the evolution of the cold ISM in AGN.

show abstract

Probing galaxy evolution through Hi 21-cm emission and absorption: current status and prospects with square kilometre array

et al. 2022

Self Cite

View full text Add to dashboard Cite

One of the major science goals of square kilometre array (SKA) is to understand the role played by atomic hydrogen (Hi) gas in the evolution of galaxies throughout cosmic time. The hyperfine transition line of the hydrogen atom at 21-cm is one of the best tools to detect and study the properties of Hi gas associated with galaxies. In this paper, we review our current understanding of Hi gas and its relationship with galaxies through observations of the 21-cm line both in emission and absorption. In addition, we provide an overview of the Hi science that will be possible with SKA and its precursors and pathfinders, i.e., Hi 21-cm emission and absorption studies of galaxies from nearby to high redshifts that will trace various processes governing galaxy evolution.

show abstract

Giant Metrewave Radio Telescope detection of associated H i 21-cm absorption atz = 1.2230 towards TXS 1954+513

Cited by 26 publications

References 39 publications

Atomic and molecular absorption in redshifted radio sources

Atomic and molecular absorption in redshifted radio sources

The interstellar and circumnuclear medium of active nuclei traced by H i 21 cm absorption

Probing galaxy evolution through Hi 21-cm emission and absorption: current status and prospects with square kilometre array

Contact Info

Product

Resources

About