A possible connection between the spin temperature of damped Lyman α absorption systems and star formation history

Curran, S. J.

doi:10.1093/mnras/stx933

Cited by 9 publications

(15 citation statements)

References 78 publications

(90 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…4 and so we can use the estimate of the mean d QSO /d abs ratio to determine the evolution of the mean covering factor from DA abs < DA QSO /4, which applies to all of sample. 5 The mean covering factors derived are similar to those obtained from the Monte-Carlo simulation of Curran (2017) and the range of mean spin temperatures are consistent with those found in the Milky Way (Dickey et al 2009) and other near-by galaxies , T spin ≈ 200 − 2000 K (Fig. 11).…”

Section: Star Formation and The Fraction Of Cold Neutral Mediumsupporting

confidence: 78%

“…3). This bears a close resemblance to the f /T spin distribution for DLAs (Curran 2017), where there is also a flattening of the distribution at low redshift. In Fig.…”

Section: Column Density Estimatessupporting

confidence: 61%

“…As discussed in Curran (2017), in order to compare the 21-cm absorption results consistently, it is necessary to normalise the sensitives. Since the spectral resolutions span a large range of values ( Fig.…”

Section: Line Strengths Of the Intervening H I 21-cm Absorbersmentioning

confidence: 99%

“…Lagos et al 2014). Recently, however, by normalising the strength of the H i 21-cm absorption (which traces the cold component of the gas) by the column density (which traces all of the neutral gas), Curran (2017) found evidence for a similarity between the fraction of cool gas and the star formation density. Although this is physically motivated, as star formation requires cold, dense, neutral gas (e.g.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

The potential of tracing the star formation history with H I 21-cm in intervening absorption systems

Curran

2017

A&A

Self Cite

View full text Add to dashboard Cite

Unlike the neutral gas density, which remains largely constant over redshifts of 0 < ∼ z < ∼ 5, the star formation density, ψ * , exhibits a strong redshift dependence, increasing from the present day before peaking at a redshift of z ≈ 2.5. Thus, there is a stark contrast between the star formation rate and the abundance of raw material available to fuel it. However, using the ratio of the strength of the H i 21-cm absorption to the total neutral gas column density to quantify the spin temperature, T spin , of the gas, it has recently been shown that 1/T spin may trace ψ * . This would be expected on the grounds that the cloud of gas must be sufficiently cool to collapse under its own gravity. This, however, relies on very limited data and so here we explore the potential of applying the above method to absorbers for which individual column densities are not available (primarily Mg ii absorption systems). By using the mean value as a proxy to the column density of the gas at a given redshift, we do, again, find that 1/T spin (degenerate with the absorber-emitter size ratio) traces ψ * . If confirmed by higher redshift data, this could offer a powerful tool for future surveys for cool gas throughout the Universe with the Square Kilometre Array.

show abstract

Section: Star Formation and The Fraction Of Cold Neutral Mediumsupporting

confidence: 78%

“…3). This bears a close resemblance to the f /T spin distribution for DLAs (Curran 2017), where there is also a flattening of the distribution at low redshift. In Fig.…”

Section: Column Density Estimatessupporting

confidence: 61%

Section: Line Strengths Of the Intervening H I 21-cm Absorbersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The potential of tracing the star formation history with H I 21-cm in intervening absorption systems

Curran

2017

A&A

Self Cite

View full text Add to dashboard Cite

show abstract

“…Rafelski et al 2012;Cooke et al 2015;De Cia et al 2018) lacked sufficient coolants in the gas to form a significant fraction of CNM via fine structure line cooling. Recently, by explicitly modelling the source covering fraction as a function of angular diameter distance, Curran (2019Curran ( , 2017 used literature searches for redshifted 21-cm absorption to show that the spin temperature has evolved with the star formation rate history of the Universe. However, we caution that this uses an evolutionary model for the covering fraction of radio sources that would mimic any perceived evolution in the spin temperature and so future model-independent methods are required to verify such a claim.…”

Section: Introductionmentioning

confidence: 99%

FLASH early science – discovery of an intervening H i 21-cm absorber from an ASKAP survey of the GAMA 23 field

Allison

Sadler

Bellstedt

et al. 2020

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We present early science results from the First Large Absorption Survey in H I (FLASH), a spectroscopically blind survey for 21-cm absorption lines in cold hydrogen (H I) gas at cosmological distances using the Australian Square Kilometre Array Pathfinder (ASKAP). We have searched for H I absorption towards 1253 radio sources in the GAMA 23 field, covering redshifts between z = 0.34 and 0.79 over a sky area of approximately 50 deg 2 . In a purely blind search we did not obtain any detections of 21-cm absorbers above our reliability threshold. Assuming a fiducial value for the H I spin temperature of T spin = 100 K and source covering fraction c f = 1, the total comoving absorption path length sensitive to all Damped Lyman α Absorbers (DLAs; N HI ≥ 2 × 10 20 cm −2 ) is ∆X = 6.6 ± 0.3 (∆z = 3.7 ± 0.2) and super-DLAs (N HI ≥ 2 × 10 21 cm −2 ) is ∆X = 111 ± 6 (∆z = 63 ± 3). We estimate upper limits on the H I column density frequency distribution function that are consistent with measurements from prior surveys for redshifted optical DLAs, and nearby 21-cm emission and absorption. By cross-matching our sample of radio sources with optical spectroscopic identifications of galaxies in the GAMA 23 field, we were able to detect 21-cm absorption at z = 0.3562 towards NVSS J224500−343030, with a column density of N HI = (1.2±0.1)×10 20 (T spin /100 K) cm −2 . The absorber is associated with GAMA J22450.05−343031.7, a massive early-type galaxy at an impact parameter of 17 kpc with respect to the radio source and which may contain a massive (M HI 3 × 10 9 M ) gas disc. Such gas-rich early types are rare, but have been detected in the nearby Universe.

show abstract

Evolution of the cold gas fraction and the star formation history: Prospects with current and future radio facilities

Curran

2018

Publ. Astron. Soc. Aust.

Self Cite

View full text Add to dashboard Cite

It has recently been shown that the abundance of cold neutral gas may follow a similar evolution as the star formation history. This is physically motivated, since stars form out of this component of the neutral gas and if the case, would resolve the longstanding issue that there is a clear disparity between the total abundance of neutral gas and star forming activity over the history of the Universe. Radio-band 21-cm absorption traces the cold gas and comparison with the Lyman-α absorption, which traces all of the gas, provides a measure of the cold gas fraction, or the spin temperature, Tspin. The recent study has shown that the spin temperature (degenerate with the ratio of the absorber/emitter extent) appears to be anti-correlated with the star formation density, ψ * , with 1/Tspin undergoing a similar steep evolution as ψ * over redshifts of 0 < ∼ z < ∼ 3, whereas the total neutral hydrogen exhibits little evolution. Above z ∼ 3, where ψ * shows a steep decline with redshift, there is insufficient 21-cm data to determine whether 1/Tspin continues to follow ψ * . Knowing this is paramount in ascertaining whether the cold neutral gas does trace the star formation over the Universe's history. We explore the feasibility of resolving this with 21-cm observations of the largest contemporary sample of reliable damped Lyman-α absorption systems and conclude that, while today's largest radio interferometers can reach the required sensitivity at z < ∼ 3.5, the Square Kilometre Array is required to probe to higher redshifts.

show abstract

A possible connection between the spin temperature of damped Lyman α absorption systems and star formation history

Cited by 9 publications

References 78 publications

The potential of tracing the star formation history with H I 21-cm in intervening absorption systems

The potential of tracing the star formation history with H I 21-cm in intervening absorption systems

FLASH early science – discovery of an intervening H i 21-cm absorber from an ASKAP survey of the GAMA 23 field

Evolution of the cold gas fraction and the star formation history: Prospects with current and future radio facilities

Contact Info

Product

Resources

About