H i 21-centimetre emission from an ensemble of galaxies at an average redshift of one

Chowdhury, Aditya; Kanekar, Nissim; Chengalur, Jayaram N.; Sethi, Shiv K.; Dwarakanath, K. S.

doi:10.1038/s41586-020-2794-7

Cited by 93 publications

(172 citation statements)

References 38 publications

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“…However, unlike the situation for H i 21 cm emission stacking (e.g. Chowdhury et al 2020bChowdhury et al , 2021, the associated H i 21 cm absorption may be offset from the optical redshifts, with the centroid either blueshifted or redshifted with respect to the systemic velocity. Stacking based on the optical redshifts may then not cause the individual H i 21 cm signals to align with each other; if so, the signal-to-noise ratio on the stacked spectrum may not improve ∝ 1/ √ N, as expected for N stacked spectra.…”

Section: H I Stackingmentioning

confidence: 76%

Redshift evolution of the HI detection rate in radio-loud active galactic nuclei

Murthy,

Morganti,

Kanekar

et al. 2022

Preprint

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We present a search for associated H i 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 H i 21 cm absorption against none of our target AGNs, obtaining 3σ upper limits to the optical depth of 1% per 50 km s −1 channel. The radio luminosity of our sources is lower than that of most AGNs searched for H i 21 cm absorption at similar redshifts in the literature, and, for all targets except two, the UV luminosity is below the threshold 10 23 W Hz −1 , above which the H i in the AGN environment has been suggested to be completely ionised. We stacked the H i 21 cm spectra to obtain a more stringent limit of ≈ 0.17% per 50 km s −1 channel on the average H i 21 cm optical depth of the sample. The sample is dominated by extended radio sources, 24 of which are extended on scales of tens of kiloparsecs. Including similar extended sources at 0.7 < z < 1.0 from the literature, and comparing with a low-z sample of extended radio sources, we find statistically significant (≈ 3σ) evidence that the strength of H i 21 cm absorption towards extended radio sources is weaker at 0.7 < z < 1.0 than at z < 0.25, with a lower detection rate of H i 21 cm absorption at 0.7 < z < 1.0. Redshift evolution in the physical conditions of H i is the likely cause of the weaker associated H i 21 cm absorption at high redshifts, due to either a low H i column density or a high spin temperature in high-z AGN environments.

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Section: H I Stackingmentioning

confidence: 76%

Redshift evolution of the HI detection rate in radio-loud active galactic nuclei

Murthy,

Morganti,

Kanekar

et al. 2022

Preprint

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“…The scientific use of such H detections is to constrain the H mass function (H MF Zwaan et al 2005) at higher redshift. At present, the H content at higher redshifts is mostly measured from stacked H spectra (Fabello et al 2011(Fabello et al , 2012Delhaize et al 2013;Maddox et al 2013;Gereb et al 2015;Bera et al 2019;Guo et al 2020;Chowdhury et al 2020Chowdhury et al , 2021. With strongly lensed H detections, and a reasonable prior for the magnification distribution, a wholly separate constraint can be given on the low-mass end of the H MF.…”

Section: Discussionmentioning

confidence: 99%

“…The new H surveys, such as MIGHTEE (Jarvis et al 2016;Delhaize et al 2021;Maddox et al 2021) and LADUMA (Holwerda 2011;Blyth 2015;Blyth et al 2016;Baker et al 2018) using the MeerKAT radio telescope and WALLABY (Koribalski et al 2020) on ASKAP (Johnston et al 2008), promise a boon of H detections lensed by a closer galaxy (Deane et al 2015;Blecher et al 2019). A magnified H detection would allow these surveys to probe below their sensitivity limit to verify for example the results from stacking H spectra for a given galaxy population (cf Delhaize et al 2013;Healy et al 2021;Chowdhury et al 2020Chowdhury et al , 2021. Deane et al (2015) made predictions for the CHILES and LADUMA deep H fields (COSMOS and CDF-S respectively) are at best a single strong lens to dozens.…”

Section: Introductionmentioning

confidence: 99%

Deep Extragalactic VIsible Legacy Survey (DEVILS): DR1 Blended Spectra Search for Candidate Strong Gravitational Lenses

Holwerda,

Knabel,

Thorne

et al. 2021

Preprint

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Here, we present a catalog of blended spectra in Data Release 1 of the Deep Extragalactic VIsible Legacy Survey (DEVILS) on the Anglo-Australian Telescope (AAT). Of the 23197 spectra, 181 showed signs of a blend of redshifts and spectral templates. We examine these blends in detail for signs of either a candidate strong lensing galaxy or a useful overlapping galaxy pair.One of the three DEVILS target fields, COSMOS (D10) is close to complete and it is fully imaged with Hubble Space Telescope Advanced Camera for Surveys (HST/ACS) and we visually examine the 57 blended spectra in this field in the F814W postage stamps. Nine are classical strong lensing candidates with an elliptical as the lens, out to higher redshifts than any previous search with spectroscopic surveys such as SDSS or GAMA. The gravitational lens candidate success rate similar to earlier such searches (0.1%).Strong gravitational lenses identified with blended spectroscopy have typically shown a high success rate (>70%) which make these interesting targets for future higher resolution lensing studies, monitoring for supernovae cosmography, or searches for magnified atomic hydrogen signal.

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“…For each observing run, we made a single-channel visibility data set and performed initial editing to elide visibilities from non-working antennas and visibilities affected by radio-frequency interference (RFI). The antenna-based complex gains were estimated from this single-channel data set, using the routine GAINCALR (Chowdhury et al 2020). The edits and gains were then applied to all channels of the multi-channel data set, and the antenna-based bandpass shapes were then estimated using the routine BANDPASSR (Chowdhury et al 2020).…”

Section: Observations and Data Analysismentioning

confidence: 99%

“…The antenna-based complex gains were estimated from this single-channel data set, using the routine GAINCALR (Chowdhury et al 2020). The edits and gains were then applied to all channels of the multi-channel data set, and the antenna-based bandpass shapes were then estimated using the routine BANDPASSR (Chowdhury et al 2020). The gains and bandpasses were then applied to the visibilities of SDSS J0158+6542, and the calibrated visibilities from all epochs combined to produce a single data set.…”

Section: Observations and Data Analysismentioning

confidence: 99%

A fast radio burst progenitor born in a galaxy merger

Kaur,

Kanekar,

Prochaska

2022

Preprint

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We report a Giant Metrewave Radio Telescope HI 21 cm mapping study of the neutral atomic hydrogen (HI) in the host galaxy of the fast radio burst (FRB) FRB 20180916B at z ≈ 0.03399. We find that the FRB host has an HI mass of M HI = (2.74 ± 0.33) × 10 9 M and a high HI-to-stellar mass ratio, ≈ 1.3. The FRB host is thus a gas-rich but near-quiescent galaxy, that is likely to have acquired a significant mass of HI in the recent past. The HI distribution is disturbed, with extended HI 21 cm emission detected in a north-eastern tail, a counter-tail towards the south, an HI hole between the galaxy centre and the FRB location, and a high HI column density measured close to the FRB position. The FRB host is part of a group with four companions detected in their HI 21 cm emission, the nearest of which is only 22 kpc from the FRB location. The gas-richness and disturbed HI distribution indicate that the FRB host has recently undergone a minor merger, which increased its HI mass, disturbed the HI in the galaxy disk, and compressed the HI near the FRB location to increase its surface density. We propose that this merger caused the burst of star-formation in the outskirts of the galaxy that gave rise to the FRB progenitor. The evidence for a minor merger is consistent with scenarios in which the FRB progenitor is a massive star, formed due to the merger event.

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H i 21-centimetre emission from an ensemble of galaxies at an average redshift of one

Cited by 93 publications

References 38 publications

Redshift evolution of the HI detection rate in radio-loud active galactic nuclei

Redshift evolution of the HI detection rate in radio-loud active galactic nuclei

Deep Extragalactic VIsible Legacy Survey (DEVILS): DR1 Blended Spectra Search for Candidate Strong Gravitational Lenses

A fast radio burst progenitor born in a galaxy merger

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