An ALMA Early Science survey of molecular absorption lines toward PKS 1830−211

Müller, S.; Combes, F.; Guèlin, M.; Gérin, M.; Aalto, S.; Beelen, A.; Black, J. H.; Curran, S. J.; Darling, Jeremy; Dinh-V-Trung,; García‐Burillo, S.; Henkel, C.; Horellou, C.; Martín, S.; Martí-Vidal, Iván; Menten, K. M.; Murphy, Michael T.; Ott, J.; Wiklind, T.; Zwaan, M. A.

doi:10.1051/0004-6361/201423646

Cited by 69 publications

(121 citation statements)

References 60 publications

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“…However, the ArH + line profile shows a slight deviation from a simple Gaussian, and fit results and values of integrated opacity over velocity channels from −80 to +110 km s −1 are given in a separate column in Table 1. The weak velocity component at +170 km s −1 , previously only detected in the lines of HCO + , HCN, and H 2 O and all three strongly saturated near v = 0 km s −1 (Muller et al 2011(Muller et al , 2014b, is − surprisingly − also detected in the 36 ArH + spectrum. In contrast to the SW line of sight, where the absorption mostly resides in one bulky absorption feature (with the exception of the additional +170 km s −1 component), the ArH + absorption profile toward the NE image shows a remarkable series of narrow (a few km s −1 ) features spanning over ∼200 km s −1 , also seen, e.g., in the absorption profile of H 2 O (Muller et al 2014b).…”

Section: Column Densities and Abundancesmentioning

confidence: 76%

Detection of extragalactic argonium, ArH⁺, toward PKS 1830−211

Müller

Schilke

et al. 2015

A&A

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Context. Argonium has recently been detected as a ubiquitous molecule in our Galaxy. Model calculations indicate that its abundance peaks at molecular fractions in the range of 10 −4 to 10 −3 and that the observed column densities require high values of the cosmic ray ionization rate. Therefore, this molecular cation may serve as an excellent tracer of the very diffuse interstellar medium (ISM), as well as an indicator of the cosmic ray ionization rate. Aims. We attempted to detect ArH + in extragalactic sources to evaluate its diagnostic power as a tracer of the almost purely atomic ISM in distant galaxies. Methods. We obtained ALMA observations of a foreground galaxy at z = 0.89 in the direction of the lensed blazar PKS 1830−211. Results. Two isotopologs of argonium, 36 ArH + and 38 ArH + , were detected in absorption along two different lines of sight toward PKS 1830−211, known as the SW and NE images of the background blazar. The argonium absorption is clearly enhanced on the more diffuse line of sight (NE) compared to other molecular species. The isotopic ratio 36 Ar/ 38 Ar is 3.46 ± 0.16 toward the SW image, i.e., significantly lower than the solar value of 5.5.Conclusions. Our results demonstrate the suitability of argonium as a tracer of the almost purely atomic, diffuse ISM in high-redshift sources. The evolution of the isotopic ratio with redshift may help to constrain nucleosynthetic scenarios in the early Universe.

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Section: Column Densities and Abundancesmentioning

confidence: 76%

Detection of extragalactic argonium, ArH⁺, toward PKS 1830−211

Müller

Schilke

et al. 2015

A&A

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“…The best way to derive physical properties accurately is to detect the tracers of the cold gas in absorption (see Muller et al 2014). The neutral, shielded, and possibly cold gas clouds at high redshifts can be searched for in the radio domain by targeting the neutral atomic-hydrogen (H i) 21-cm absorption line (e.g., Gupta et al 2009).…”

Section: Introductionmentioning

confidence: 99%

Neutral atomic-carbon quasar absorption-line systems atz> 1.5

Ledoux

Noterdaeme

Petitjean

et al. 2015

A&A

125

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We present the results of a search for cold gas at high redshift along quasar lines of sight carried out without any a priori assumption on the neutral atomic-hydrogen content of the absorption-line systems. To do this, we systematically looked for neutral-carbon (C i) λλ1560, 1656 transition lines in 41 696 low-resolution quasar spectra (1.5 < z em < 4.46) from the SDSS-II -Data Release 7 -database. C i absorption lines should indeed probe the shielded gas in the neutral interstellar medium of galaxies more efficiently than traditional tracers such as neutral atomic-hydrogen (H i) damped Lyman-α (DLA) and/or Mg ii systems. We built up a sample of 66 C i absorbers with redshifts in the range 1.5 < z < 3.1 and rest-frame equivalent widths 0.1 < W r (λ1560) < 1.7 Å. The completeness limit of our survey is W r,lim (λ1560) 0.4 Å. C i systems stronger than that are more than one hundred times rarer than DLAs at z abs = 2.5. The number of C i systems per unit redshift is found to increase significantly below z = 2. We suggest that these C i absorbers are closely related to the process of star formation and the production of dust in galaxies and that their cosmic evolution is driven by the interplay between dust shielding and the evolution of the ultra-violet background at ∼10 eV. We derive the neutral atomic-hydrogen content of the C i systems observable from the southern hemisphere from VLT/UVES spectroscopy and find that a majority of them are sub-DLAs with N(H i) ∼ 10 20 atoms cm −2 . The dust content of these absorbers is yet significant as seen from the redder optical colours of the corresponding background quasars and their reddened spectral energy distributions, with E(B − V) values up to ∼0.3. The overall N(H i) distribution of C i systems is, however, relatively flat. As a consequence, among the C i systems classifying as DLAs, there is a probable excess of strong DLAs with log N(H i) > 21 (atoms cm −2 ) compared to systematic DLA surveys. Whilst the dust content of such systems is significant, their dust-to-gas ratio must still be limited. Indeed, strong DLAs having large amounts of shielded gas and dust producing stronger reddening and extinction of the background quasars, if they exist, should have been missed in the current magnitude-limited quasar sample. We study the empirical relations between W r (C i), N(H i), E(B − V), and the strength of the 2175 Å extinction feature. The latter is detected in about 30% of the C i absorbers. We show that, at equal amount of reddening, the 2175 Å feature is weak compared to Galactic lines of sight. This is probably the consequence of current or past star formation in the vicinity of the C i systems. We also find that the strongest C i systems tend to have the largest amounts of dust and that the metallicity of the gas and its molecular fraction is likely to be high in a large number of cases. The C i-absorber sample presented here hence provides ideal targets for detailed studies of the dust composition and molecular species at high redshift.

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“…Most of the deep and/or unbiased chemical studies in galaxies have been carried out at very low resolution (i.e., 100 pc, Wang et al 2004;Martín et al 2006Martín et al , 2011Aladro et al 2011aAladro et al , 2013Davis et al 2013;Watanabe et al 2014) but for absorption studies toward bright continuum high-z sources where, though extremely prolific in molecular detection, no spatial information can be obtained (Muller et al 2011(Muller et al , 2014. High resolution studies toward extragalactic sources have mostly focused toward the brightest nearby galaxies, as well as on the brightest species after carbon monoxide: HCN and HCO + (NGC 253 at 3 resolution, Knudsen et al (2007); M51 at 4 , Schinnerer et al 2010; NGC 1068 at 1 , Krips et al 2011; NGC 1097 at 3 , Hsieh et al 2012; or a sample of luminous infrarred galaxies (LIRGs) at 2 −10 , Imanishi et al 2007Imanishi et al , 2009).…”

Section: Introductionmentioning

confidence: 99%

Multimolecule ALMA observations toward the Seyfert 1 galaxy NGC 1097

Martín

Kohno

Izumi

et al. 2015

A&A

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Context. The nearby Sy 1 galaxy NGC 1097 represents an ideal laboratory for exploring the molecular chemistry in the surroundings of an active galactic nucleus (AGN). Aims. Exploring the distribution of different molecular species allows us to understand the physical processes affecting the interstellar medium both in the AGN vicinity and in the outer star forming molecular ring. Methods. We carried out 3 mm ALMA observations that include seven different molecular species, namely HCN, HCO + , CCH, CS, HNCO, SiO, HC 3 N, and SO, as well as the 13 C isotopologues of the first two. Spectra were extracted from selected positions and all species were imaged over the central 2 kpc (∼30 ) of the galaxy at a resolution of ∼2.2 × 1.5 (150 pc × 100 pc). Results. HCO + and CS appear to be slightly enhanced in the star forming ring. CCH shows the largest variations across NGC 1097 and is suggested to be a good tracer of both obscured and early stage star formation. HNCO, SiO, and HC 3 N are significantly enhanced in the inner circumnuclear disk surrounding the AGN. Conclusions. Differences in the molecular abundances are observed between the star forming ring and the inner circumnuclear disk. We conclude that the HCN/HCO + and HCN/CS differences observed between AGN-dominated and starburst (SB) galaxies are not due to a HCN enhancement due to X-rays, but rather this enhancement is produced by shocked material at distances of 200 pc from the AGN. Additionally, we claim that lower HCN/CS is a combination of a small underabundance of CS in AGNs, together with excitation effects, where a high density gas component (∼10 6 cm −3 ) may be more prominent in SB galaxies. However, the most promising are the differences found among the dense gas tracers that, at our modest spatial resolution, seem to outline the physical structure of the molecular disk around the AGN. In this picture, HNCO probes the well-shielded gas in the disk, surrounding the dense material moderately exposed to the X-ray radiation traced by HC 3 N. Finally SiO might be the innermost molecule in the disk structure.

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An ALMA Early Science survey of molecular absorption lines toward PKS 1830−211

Cited by 69 publications

References 60 publications

Detection of extragalactic argonium, ArH⁺, toward PKS 1830−211

Detection of extragalactic argonium, ArH⁺, toward PKS 1830−211

Neutral atomic-carbon quasar absorption-line systems atz> 1.5

Multimolecule ALMA observations toward the Seyfert 1 galaxy NGC 1097

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An ALMA Early Science survey of molecular absorption lines toward PKS 1830−211

Cited by 69 publications

References 60 publications

Detection of extragalactic argonium, ArH+, toward PKS 1830−211

Detection of extragalactic argonium, ArH+, toward PKS 1830−211

Neutral atomic-carbon quasar absorption-line systems atz> 1.5

Multimolecule ALMA observations toward the Seyfert 1 galaxy NGC 1097

Contact Info

Product

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Detection of extragalactic argonium, ArH⁺, toward PKS 1830−211

Detection of extragalactic argonium, ArH⁺, toward PKS 1830−211