Multicomponent H2 in DLA at zabs = 2.05: physical conditions through observations and numerical models★

Rawlins, K.; Srianand, R.; Shaw, Gargi; Rahmani, H.; Dutta, Rajeshwari; Chacko, Sajeev

doi:10.1093/mnras/sty2321

Cited by 19 publications

(23 citation statements)

References 100 publications

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“…The chosen radiation field has three components: a meta-galactic radiation at appropriate redshift (Haardt & Madau 2012), a synchrotron radiation (power-law continuum) arising from GRB afterglow and a blackbody radiation from in situ star formation. Our GRB-DLA models are similar to our previous QSO-DLA models (Srianand et al 2005a;Shaw et al 2016;Rawlins et al 2018) except that here we have an additional synchrotron radiation arising from GRB afterglows. While the gas is exposed to UV radiation from everywhere it is exposed to GRB afterglow only from one side.…”

Section: Modellingsupporting

confidence: 83%

Physical conditions in two high-redshift H2-bearing GRB-DLAs, 120815A and 121024A

Shaw

Ferland

2020

Monthly Notices of the Royal Astronomical Society

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The gamma-ray burst (GRB) afterglows provide an unique opportunity to study the interstellar medium (ISM) of star-forming galaxies at high-redshift. The GRB-DLAs (damped Lyman-α absorbers) contain a large neutral hydrogen column density, N(H I), and are observed against the GRB afterglow. A large fraction of GRB-DLAs show presence of molecular hydrogen (H 2 ) which is an indicator of star-formation. Hence it is important to study those GRB-DLAs which have H 2 lines to decipher and understand their physical conditions. The GRB-DLAs 121024A and 120815A, situated at redshift 2.30 and 2.36 respectively, are two such important H 2 -bearing GRB-DLAs. Besides H 2 , these two GRB-DLAs also show many metal lines. In this work we have carried out a detail numerical study on the H 2 lines, as well as on those metal lines, in GRB-DLAs 121024A and 120815A self-consistently. We use the spectral synthesis code CLOUDY for this study. This modeling helps us to determine the underlying physical conditions which give rise such lines and hence to understand these two GRB-DLAs in much more detail than any other previous investigation. We find that the hydrogen densities for these two H 2 -bearing DLAs are ≥ 60 cm −3 . Moreover our study infers that the linear sizes are ≤ 17.7 pc for these two GRB-DLAs, and the mean gas temperatures averaged over the cloud thickness, are ≤ 140 K. Overall, we find that these two H 2 -bearing GRB-DLAs are denser, cooler and smaller compared to those without H 2 .

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Section: Modellingsupporting

confidence: 83%

Physical conditions in two high-redshift H2-bearing GRB-DLAs, 120815A and 121024A

Shaw

Ferland

2020

Monthly Notices of the Royal Astronomical Society

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“…The dust-to-gas ratio in this system could be higher than that observed in the SMC, i.e. κ could be greater than unity, as is possible in high-z absorbers due to different grain chemistry or size (see Shaw et al 2016;Noterdaeme et al 2017;Dutta et al 2017b;Rawlins et al 2018). This is similar to what is inferred from the lack of H i 21-cm absorption towards the red quasar J0956+4046 (see Section 2.1.1 and Gupta et al 2012).…”

Section: H I 21-cm Absorption Towards J1521+5508supporting

confidence: 74%

uGMRT search for cold gas at z ∼ 1–1.4 towards red quasars

Dutta

Raghunathan

Gupta

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We present results from our search for H i 21-cm and OH 18-cm absorption at z ∼ 1 − 1.4 towards red quasars showing strong Mg ii absorption using uGMRT. The quasars J1501+1822 and J1521+5508 show multiple strong associated Mg ii absorption at z ∼ 1.1 and signature of reddening in their optical spectra. We report the detection of H i 21-cm absorption towards J1521+5508 at the systemic redshift of the quasar, with N (H i) = (1.2 ± 0.2) × 10 20 cm −2 for spin temperature of 100 K and unit covering factor. The H i 21-cm absorption is offset from the blueshifted strong Mg ii absorbers by 1500 km s −1 . We do not detect H i 21-cm absorption at the redshift of the associated Mg ii absorption and at the systemic redshift towards J1501+1822. We argue that lack of one-to-one correspondence between Mg ii and H i 21-cm absorption could be related with clumpiness of the neutral gas and the radio and optical sightlines probing different volume of the gas. We find that the presence of strong associated Mg ii absorption and reddening in the optical spectra of the quasars lead to an increased detection rate of associated H i 21-cm absorption at z 1. We also report non-detection of intervening OH absorption ([OH]/[H i] (1-4)×10 −8 ) at z = 1.3 towards two red quasars, J0850+5159 and J0852+3435, which show strong metal and H i 21-cm absorption and the 2175Å dust extinction bump.

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“…The UVES data include the system at z = 3.09 towards J 1311+2225, recently reported by Noterdaeme et al (2018), where C i together with H2 and CO molecules were detected, the well-known three ESDLA systems at z = 2.402 towards HE0027−1836 (Noterdaeme et al 2007) (for which further data was obtained by Rahmani et al (2013), leading to an improved quality spectrum), at z = 3.85 towards J 0816+1446 (Guimarães et al 2012), at z = 2.48 towards J 2140−0321 Noterdaeme et al (2010), and the DLA system towards J 2340-0053 where HD was reported independently and almost simultaneously by Kosenko & Balashev (2018) and Rawlins et al (2018). For this latter system, we refitted HD together with H2 and C i lines to obtain self-consistent priors on physical parameters that are used to derive the CRIR.…”

Section: Datamentioning

confidence: 80%

“…If the H2 column density is large enough, the less abundant isotopologue, HD, can also be detected (Varshalovich et al 2001). To date, HD lines have been detected only in twelve intervening systems among ∼ 40 confirmed H2-bearing DLAs at high redshift (> 0) (Noterdaeme et al 2008;Balashev et al 2010;Tumlinson et al 2010;Ivanchik et al 2010;Noterdaeme et al 2010;Klimenko et al 2015;Ivanchik et al 2015;Klimenko et al 2016;Noterdaeme et al 2017;Balashev et al 2017;Rawlins et al 2018;Kosenko & Balashev 2018). This number remains limited since the detailed analysis of H2 and HD lines can be done only in high-resolution quasar spectra, which require observations with the largest optical telescopes.…”

mentioning

confidence: 99%

HD molecules at high redshift: cosmic-ray ionization rate in the diffuse interstellar medium

Kosenko,

Balashev,

Noterdaeme

et al. 2021

Preprint

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We present a systematic study of deuterated molecular hydrogen (HD) at high redshift, detected in absorption in the spectra of quasars. We present four new identifications of HD lines associated with known H 2 -bearing Damped Lyman-α systems. In addition, we measure upper limits on the HD column density in twelve recently identified H 2 -bearing DLAs. We find that the new HD detections have similar N (HD)/N (H 2 ) ratios as previously found, further strengthening a marked difference with measurements through the Galaxy. This is likely due to differences in physical conditions and metallicity between the local and the high-redshift interstellar media. Using the measured N (HD)/N (H 2 ) ratios together with priors on the UV flux (χ) and number densities (n), obtained from analysis of H 2 and associated C i lines, we are able to constrain the cosmic-ray ionization rate (CRIR, ζ) for the new HD detections and for eight known HD-bearing systems where priors on n and χ are available. We find significant dispersion in ζ, from a few ×10 −18 s −1 to a few ×10 −15 s −1 . We also find that ζ strongly correlates with χ -showing almost quadratic dependence, slightly correlates with Z, and does not correlate with n, which probably reflects a physical connection between cosmic rays and star-forming regions.

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Multicomponent H2 in DLA at zabs = 2.05: physical conditions through observations and numerical models★

Cited by 19 publications

References 100 publications

Physical conditions in two high-redshift H2-bearing GRB-DLAs, 120815A and 121024A

Physical conditions in two high-redshift H2-bearing GRB-DLAs, 120815A and 121024A

uGMRT search for cold gas at z ∼ 1–1.4 towards red quasars

HD molecules at high redshift: cosmic-ray ionization rate in the diffuse interstellar medium

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