Towards the first detection of strongly lensed H I emission

Tariq Blecher, Roger Deane, Ian Heywood, Danail Obreschkow

Research output: Contribution to journalArticle

Abstract

We report interferometric observations tuned to the redshifted neutral hydrogen (H I) 21cm emission line in three strongly lensed galaxies at z similar to 0.4 with the Giant Metrewave Radio Telescope. One galaxy spectrum (J1106+5228 at z = 0.407) shows evidence of a marginal detection with an integrated signal-to-noise ratio of 3.8, which, if confirmed by follow-up observations, would represent the first strongly lensed and most distant individual galaxy detected in H I emission. Two steps are performed to transcribe the lensed integrated flux measurements into H I mass measurements for all three target galaxies. First, we calculate the H I magnification factor mu by applying general relativistic ray tracing to a physical model of the source-lens system. The H I magnification generally differs from the optical magnification and depends largely on the intrinsic H I mass M-H I due to the H I mass-size relation. Secondly, we employ a Bayesian formalism to convert the integrated flux, amplified by the M-HI-dependent magnification factor mu, into a probability density for M-H I, accounting for the asymmetric uncertainty due to the declining H I mass function (Eddington bias). In this way, we determine a value of log(10) (M-H I/M-circle dot) = 10.2(-0.7)(+0.3) for J1106+5228, consistent with the estimate of 9.4 +/- 0.3 from the optical properties of this galaxy. The H I mass of the other two sources are consistent with zero within a 95 per cent confidence interval however we still provide upper limits for both sources and a l sigma lower limit for J1250-0135 using the same formalism.

Original languageEnglish
Pages (from-to)3681-3690
Number of pages10
JournalMonthly Notices of the Royal Astronomical Society
Volume484
Issue number3
DOIs
Publication statusPublished - Apr 2019

Cite this

Blecher, Tariq ; Deane, Roger ; Heywood, Ian ; Obreschkow, Danail. / Towards the first detection of strongly lensed H I emission. In: Monthly Notices of the Royal Astronomical Society. 2019 ; Vol. 484, No. 3. pp. 3681-3690.
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abstract = "We report interferometric observations tuned to the redshifted neutral hydrogen (H I) 21cm emission line in three strongly lensed galaxies at z similar to 0.4 with the Giant Metrewave Radio Telescope. One galaxy spectrum (J1106+5228 at z = 0.407) shows evidence of a marginal detection with an integrated signal-to-noise ratio of 3.8, which, if confirmed by follow-up observations, would represent the first strongly lensed and most distant individual galaxy detected in H I emission. Two steps are performed to transcribe the lensed integrated flux measurements into H I mass measurements for all three target galaxies. First, we calculate the H I magnification factor mu by applying general relativistic ray tracing to a physical model of the source-lens system. The H I magnification generally differs from the optical magnification and depends largely on the intrinsic H I mass M-H I due to the H I mass-size relation. Secondly, we employ a Bayesian formalism to convert the integrated flux, amplified by the M-HI-dependent magnification factor mu, into a probability density for M-H I, accounting for the asymmetric uncertainty due to the declining H I mass function (Eddington bias). In this way, we determine a value of log(10) (M-H I/M-circle dot) = 10.2(-0.7)(+0.3) for J1106+5228, consistent with the estimate of 9.4 +/- 0.3 from the optical properties of this galaxy. The H I mass of the other two sources are consistent with zero within a 95 per cent confidence interval however we still provide upper limits for both sources and a l sigma lower limit for J1250-0135 using the same formalism.",
keywords = "gravitational lensing: strong, techniques: interferometric, galaxies: evolution, galaxies: high-redshift, radio lines: galaxies, COSMIC EVOLUTION, GALAXIES, GAS, HYDROGEN",
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Towards the first detection of strongly lensed H I emission. / Blecher, Tariq; Deane, Roger; Heywood, Ian; Obreschkow, Danail.

In: Monthly Notices of the Royal Astronomical Society, Vol. 484, No. 3, 04.2019, p. 3681-3690.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Towards the first detection of strongly lensed H I emission

AU - Blecher, Tariq

AU - Deane, Roger

AU - Heywood, Ian

AU - Obreschkow, Danail

PY - 2019/4

Y1 - 2019/4

N2 - We report interferometric observations tuned to the redshifted neutral hydrogen (H I) 21cm emission line in three strongly lensed galaxies at z similar to 0.4 with the Giant Metrewave Radio Telescope. One galaxy spectrum (J1106+5228 at z = 0.407) shows evidence of a marginal detection with an integrated signal-to-noise ratio of 3.8, which, if confirmed by follow-up observations, would represent the first strongly lensed and most distant individual galaxy detected in H I emission. Two steps are performed to transcribe the lensed integrated flux measurements into H I mass measurements for all three target galaxies. First, we calculate the H I magnification factor mu by applying general relativistic ray tracing to a physical model of the source-lens system. The H I magnification generally differs from the optical magnification and depends largely on the intrinsic H I mass M-H I due to the H I mass-size relation. Secondly, we employ a Bayesian formalism to convert the integrated flux, amplified by the M-HI-dependent magnification factor mu, into a probability density for M-H I, accounting for the asymmetric uncertainty due to the declining H I mass function (Eddington bias). In this way, we determine a value of log(10) (M-H I/M-circle dot) = 10.2(-0.7)(+0.3) for J1106+5228, consistent with the estimate of 9.4 +/- 0.3 from the optical properties of this galaxy. The H I mass of the other two sources are consistent with zero within a 95 per cent confidence interval however we still provide upper limits for both sources and a l sigma lower limit for J1250-0135 using the same formalism.

AB - We report interferometric observations tuned to the redshifted neutral hydrogen (H I) 21cm emission line in three strongly lensed galaxies at z similar to 0.4 with the Giant Metrewave Radio Telescope. One galaxy spectrum (J1106+5228 at z = 0.407) shows evidence of a marginal detection with an integrated signal-to-noise ratio of 3.8, which, if confirmed by follow-up observations, would represent the first strongly lensed and most distant individual galaxy detected in H I emission. Two steps are performed to transcribe the lensed integrated flux measurements into H I mass measurements for all three target galaxies. First, we calculate the H I magnification factor mu by applying general relativistic ray tracing to a physical model of the source-lens system. The H I magnification generally differs from the optical magnification and depends largely on the intrinsic H I mass M-H I due to the H I mass-size relation. Secondly, we employ a Bayesian formalism to convert the integrated flux, amplified by the M-HI-dependent magnification factor mu, into a probability density for M-H I, accounting for the asymmetric uncertainty due to the declining H I mass function (Eddington bias). In this way, we determine a value of log(10) (M-H I/M-circle dot) = 10.2(-0.7)(+0.3) for J1106+5228, consistent with the estimate of 9.4 +/- 0.3 from the optical properties of this galaxy. The H I mass of the other two sources are consistent with zero within a 95 per cent confidence interval however we still provide upper limits for both sources and a l sigma lower limit for J1250-0135 using the same formalism.

KW - gravitational lensing: strong

KW - techniques: interferometric

KW - galaxies: evolution

KW - galaxies: high-redshift

KW - radio lines: galaxies

KW - COSMIC EVOLUTION

KW - GALAXIES

KW - GAS

KW - HYDROGEN

U2 - 10.1093/mnras/stz224

DO - 10.1093/mnras/stz224

M3 - Article

VL - 484

SP - 3681

EP - 3690

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 3

ER -