Molecular hydrogen in the damped Lyman alpha system towards GRB 120815A at z=2.36

T. Krühler; C. Ledoux; J.~P.~U. Fynbo; P.~M. Vreeswijk; S. Schmidl; D. Malesani; Lise Bech Christensen; A. De Cia; J. Hjorth; P. Jakobsson; D.~A. Kann; L. Kaper; S.~D. Vergani; P.~M.~J. Afonso; S. Covino; A. de Ugarte Postigo; V. D'Elia; R. Filgas; P. Goldoni; J. Greiner; O.~E. Hartoog; B. Milvang-Jensen; M. Nardini; S. Piranomonte; A. Rossi; R. Sánchez-Ramírez; P. Schady; S. Schulze; V. Sudilovsky; N.~R. Tanvir; G. Tagliaferri; D.~J. Watson; K. Wiersema; R.~A.~M.~J. Wijers; D. Xu; Georgios Leloudas

doi:10.1051/0004-6361/201321772

Molecular hydrogen in the damped Lyman alpha system towards GRB 120815A at z=2.36

T. Krühler, C. Ledoux, J.~P.~U. Fynbo, P.~M. Vreeswijk, S. Schmidl, D. Malesani, Lise Bech Christensen, A. De Cia, J. Hjorth, P. Jakobsson, D.~A. Kann, L. Kaper, S.~D. Vergani, P.~M.~J. Afonso, S. Covino, A. de Ugarte Postigo, V. D'Elia, R. Filgas, P. Goldoni, J. GreinerO.~E. Hartoog, B. Milvang-Jensen, M. Nardini, S. Piranomonte, A. Rossi, R. Sánchez-Ramírez, P. Schady, S. Schulze, V. Sudilovsky, N.~R. Tanvir, G. Tagliaferri, D.~J. Watson, K. Wiersema, R.~A.~M.~J. Wijers, D. Xu, Georgios Leloudas

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62 Citationer (Scopus)

Abstract

We present the discovery of molecular hydrogen (H₂), including the presence of vibrationally-excited H₂ in the optical spectrum of the afterglow of GRB 120815A at z = 2:36 obtained with X-shooter at the VLT. Simultaneous photometric broad-band data from GROND and X-ray observations by Swift/XRT place further constraints on the amount and nature of dust along the sightline. The galactic environment of GRB 120815A is characterized by a strong DLA with log(N(Hi)=cm^-2) = 21:95 ± 0:10, prominent H ₂ absorption in the Lyman-Werner bands (log(N(H₂)=cm ^-2) = 20:54 ± 0:13) and thus a molecular gas fraction log f (H₂) = -1:14 ± 0:15. The distance d between the absorbing neutral gas and GRB 120815A is constrained via photo-excitation modeling of fine-structure and meta-stable transitions of Fe ii and Ni ii to d = 0:5 ± 0:1 kpc. The DLA metallicity ([Zn=H] = -1:15 ± 0:12), visual extinction (A_V 0:15 mag) and dust depletion ([Zn=Fe] = 1:01 ± 0:10) are intermediate between the values of well-studied, H₂- deficient GRB-DLAs observed at high spectral resolution, and the approximately solar metallicity, highly-obscured and H₂-rich GRB 080607 sightline. With respect to N(Hi), metallicity, as well as dust-extinction and depletion, GRB 120815A is fairly representative of the average properties of GRB-DLAs. This demonstrates that molecular hydrogen is present in at least a fraction of the more typical GRBDLAs, and H₂ and H₂ are probably more wide-spread among GRB-selected systems than the few examples of previous detections would suggest. Because H₂ transitions are located redwards of the Lyman α absorption, H₂ opens a second route for positive searches for molecular absorption also in GRB afterglows at lower redshifts and observed at lower spectral resolution. Further detections of molecular gas in GRB-DLAs would allow statistical studies, and, coupled with host follow-up and sub-mm spectroscopy, provide unprecedented insights into the process and conditions of star-formation at high redshift.

Originalsprog	Engelsk
Artikelnummer	A18
Tidsskrift	Astronomy & Astrophysics
Vol/bind	557
ISSN	0004-6361
DOI	https://doi.org/10.1051/0004-6361/201321772
Status	Udgivet - 1 sep. 2013

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10.1051/0004-6361/201321772

Citationsformater

Krühler, T., Ledoux, C., Fynbo, J. P. U., Vreeswijk, P. M., Schmidl, S., Malesani, D., Christensen, L. B., De Cia, A., Hjorth, J., Jakobsson, P., Kann, D. A., Kaper, L., Vergani, S. D., Afonso, P. M. J., Covino, S., de Ugarte Postigo, A., D'Elia, V., Filgas, R., Goldoni, P., ... Leloudas, G. (2013). Molecular hydrogen in the damped Lyman alpha system towards GRB 120815A at z=2.36. Astronomy & Astrophysics, 557, [A18]. https://doi.org/10.1051/0004-6361/201321772

Krühler, T, Ledoux, C, Fynbo, JPU, Vreeswijk, PM, Schmidl, S, Malesani, D , Christensen, LB, De Cia, A, Hjorth, J, Jakobsson, P, Kann, DA, Kaper, L, Vergani, SD, Afonso, PMJ, Covino, S, de Ugarte Postigo, A, D'Elia, V, Filgas, R, Goldoni, P, Greiner, J, Hartoog, OE, Milvang-Jensen, B, Nardini, M, Piranomonte, S, Rossi, A, Sánchez-Ramírez, R, Schady, P, Schulze, S, Sudilovsky, V, Tanvir, NR, Tagliaferri, G, Watson, DJ, Wiersema, K, Wijers, RAMJ, Xu, D & Leloudas, G 2013, 'Molecular hydrogen in the damped Lyman alpha system towards GRB 120815A at z=2.36', Astronomy & Astrophysics, bind 557, A18. https://doi.org/10.1051/0004-6361/201321772

@article{5b6d371c836a45b58a72f0cdb5dc1b8b,

title = "Molecular hydrogen in the damped Lyman alpha system towards GRB 120815A at z=2.36",

abstract = "We present the discovery of molecular hydrogen (H2), including the presence of vibrationally-excited H2 in the optical spectrum of the afterglow of GRB 120815A at z = 2:36 obtained with X-shooter at the VLT. Simultaneous photometric broad-band data from GROND and X-ray observations by Swift/XRT place further constraints on the amount and nature of dust along the sightline. The galactic environment of GRB 120815A is characterized by a strong DLA with log(N(Hi)=cm-2) = 21:95 ± 0:10, prominent H 2 absorption in the Lyman-Werner bands (log(N(H2)=cm -2) = 20:54 ± 0:13) and thus a molecular gas fraction log f (H2) = -1:14 ± 0:15. The distance d between the absorbing neutral gas and GRB 120815A is constrained via photo-excitation modeling of fine-structure and meta-stable transitions of Fe ii and Ni ii to d = 0:5 ± 0:1 kpc. The DLA metallicity ([Zn=H] = -1:15 ± 0:12), visual extinction (AV 0:15 mag) and dust depletion ([Zn=Fe] = 1:01 ± 0:10) are intermediate between the values of well-studied, H2- deficient GRB-DLAs observed at high spectral resolution, and the approximately solar metallicity, highly-obscured and H2-rich GRB 080607 sightline. With respect to N(Hi), metallicity, as well as dust-extinction and depletion, GRB 120815A is fairly representative of the average properties of GRB-DLAs. This demonstrates that molecular hydrogen is present in at least a fraction of the more typical GRBDLAs, and H2 and H2 are probably more wide-spread among GRB-selected systems than the few examples of previous detections would suggest. Because H2 transitions are located redwards of the Lyman α absorption, H2 opens a second route for positive searches for molecular absorption also in GRB afterglows at lower redshifts and observed at lower spectral resolution. Further detections of molecular gas in GRB-DLAs would allow statistical studies, and, coupled with host follow-up and sub-mm spectroscopy, provide unprecedented insights into the process and conditions of star-formation at high redshift.",

keywords = "galaxies: ISM, gamma-ray burst: individual: GRB 120815A, galaxies: high-redshift, ISM: molecules, dust, extinction",

author = "T. Kr{\"u}hler and C. Ledoux and J.~P.~U. Fynbo and P.~M. Vreeswijk and S. Schmidl and D. Malesani and Christensen, {Lise Bech} and {De Cia}, A. and J. Hjorth and P. Jakobsson and D.~A. Kann and L. Kaper and S.~D. Vergani and P.~M.~J. Afonso and S. Covino and {de Ugarte Postigo}, A. and V. D'Elia and R. Filgas and P. Goldoni and J. Greiner and O.~E. Hartoog and B. Milvang-Jensen and M. Nardini and S. Piranomonte and A. Rossi and R. S{\'a}nchez-Ram{\'i}rez and P. Schady and S. Schulze and V. Sudilovsky and N.~R. Tanvir and G. Tagliaferri and D.~J. Watson and K. Wiersema and R.~A.~M.~J. Wijers and D. Xu and Georgios Leloudas",

year = "2013",

month = sep,

day = "1",

doi = "10.1051/0004-6361/201321772",

language = "English",

volume = "557",

journal = "Astronomy and Astrophysics Supplement Series",

issn = "0004-6361",

publisher = "E D P Sciences",

}

TY - JOUR

T1 - Molecular hydrogen in the damped Lyman alpha system towards GRB 120815A at z=2.36

AU - Krühler, T.

AU - Ledoux, C.

AU - Fynbo, J.~P.~U.

AU - Vreeswijk, P.~M.

AU - Schmidl, S.

AU - Malesani, D.

AU - Christensen, Lise Bech

AU - De Cia, A.

AU - Hjorth, J.

AU - Jakobsson, P.

AU - Kann, D.~A.

AU - Kaper, L.

AU - Vergani, S.~D.

AU - Afonso, P.~M.~J.

AU - Covino, S.

AU - de Ugarte Postigo, A.

AU - D'Elia, V.

AU - Filgas, R.

AU - Goldoni, P.

AU - Greiner, J.

AU - Hartoog, O.~E.

AU - Milvang-Jensen, B.

AU - Nardini, M.

AU - Piranomonte, S.

AU - Rossi, A.

AU - Sánchez-Ramírez, R.

AU - Schady, P.

AU - Schulze, S.

AU - Sudilovsky, V.

AU - Tanvir, N.~R.

AU - Tagliaferri, G.

AU - Watson, D.~J.

AU - Wiersema, K.

AU - Wijers, R.~A.~M.~J.

AU - Xu, D.

AU - Leloudas, Georgios

PY - 2013/9/1

Y1 - 2013/9/1

N2 - We present the discovery of molecular hydrogen (H2), including the presence of vibrationally-excited H2 in the optical spectrum of the afterglow of GRB 120815A at z = 2:36 obtained with X-shooter at the VLT. Simultaneous photometric broad-band data from GROND and X-ray observations by Swift/XRT place further constraints on the amount and nature of dust along the sightline. The galactic environment of GRB 120815A is characterized by a strong DLA with log(N(Hi)=cm-2) = 21:95 ± 0:10, prominent H 2 absorption in the Lyman-Werner bands (log(N(H2)=cm -2) = 20:54 ± 0:13) and thus a molecular gas fraction log f (H2) = -1:14 ± 0:15. The distance d between the absorbing neutral gas and GRB 120815A is constrained via photo-excitation modeling of fine-structure and meta-stable transitions of Fe ii and Ni ii to d = 0:5 ± 0:1 kpc. The DLA metallicity ([Zn=H] = -1:15 ± 0:12), visual extinction (AV 0:15 mag) and dust depletion ([Zn=Fe] = 1:01 ± 0:10) are intermediate between the values of well-studied, H2- deficient GRB-DLAs observed at high spectral resolution, and the approximately solar metallicity, highly-obscured and H2-rich GRB 080607 sightline. With respect to N(Hi), metallicity, as well as dust-extinction and depletion, GRB 120815A is fairly representative of the average properties of GRB-DLAs. This demonstrates that molecular hydrogen is present in at least a fraction of the more typical GRBDLAs, and H2 and H2 are probably more wide-spread among GRB-selected systems than the few examples of previous detections would suggest. Because H2 transitions are located redwards of the Lyman α absorption, H2 opens a second route for positive searches for molecular absorption also in GRB afterglows at lower redshifts and observed at lower spectral resolution. Further detections of molecular gas in GRB-DLAs would allow statistical studies, and, coupled with host follow-up and sub-mm spectroscopy, provide unprecedented insights into the process and conditions of star-formation at high redshift.

AB - We present the discovery of molecular hydrogen (H2), including the presence of vibrationally-excited H2 in the optical spectrum of the afterglow of GRB 120815A at z = 2:36 obtained with X-shooter at the VLT. Simultaneous photometric broad-band data from GROND and X-ray observations by Swift/XRT place further constraints on the amount and nature of dust along the sightline. The galactic environment of GRB 120815A is characterized by a strong DLA with log(N(Hi)=cm-2) = 21:95 ± 0:10, prominent H 2 absorption in the Lyman-Werner bands (log(N(H2)=cm -2) = 20:54 ± 0:13) and thus a molecular gas fraction log f (H2) = -1:14 ± 0:15. The distance d between the absorbing neutral gas and GRB 120815A is constrained via photo-excitation modeling of fine-structure and meta-stable transitions of Fe ii and Ni ii to d = 0:5 ± 0:1 kpc. The DLA metallicity ([Zn=H] = -1:15 ± 0:12), visual extinction (AV 0:15 mag) and dust depletion ([Zn=Fe] = 1:01 ± 0:10) are intermediate between the values of well-studied, H2- deficient GRB-DLAs observed at high spectral resolution, and the approximately solar metallicity, highly-obscured and H2-rich GRB 080607 sightline. With respect to N(Hi), metallicity, as well as dust-extinction and depletion, GRB 120815A is fairly representative of the average properties of GRB-DLAs. This demonstrates that molecular hydrogen is present in at least a fraction of the more typical GRBDLAs, and H2 and H2 are probably more wide-spread among GRB-selected systems than the few examples of previous detections would suggest. Because H2 transitions are located redwards of the Lyman α absorption, H2 opens a second route for positive searches for molecular absorption also in GRB afterglows at lower redshifts and observed at lower spectral resolution. Further detections of molecular gas in GRB-DLAs would allow statistical studies, and, coupled with host follow-up and sub-mm spectroscopy, provide unprecedented insights into the process and conditions of star-formation at high redshift.

KW - galaxies: ISM, gamma-ray burst: individual: GRB 120815A, galaxies: high-redshift, ISM: molecules, dust, extinction

U2 - 10.1051/0004-6361/201321772

DO - 10.1051/0004-6361/201321772

M3 - Journal article

SN - 0004-6361

VL - 557

JO - Astronomy and Astrophysics Supplement Series

JF - Astronomy and Astrophysics Supplement Series

M1 - A18

ER -

Molecular hydrogen in the damped Lyman alpha system towards GRB 120815A at z=2.36

Abstract

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