Ionised gas structure of 100 kpc in an over-dense region of the galaxy group COSMOS-Gr30 at z ~ 0.7

Benoît Epinat; Thierry Contini; Hayley Finley; Leindert Boogaard; Adrien Guérou; Jarle Brinchmann; David Carton; Léo Michel-Dansac; Roland Bacon; Sebastiano Cantalupo; Marcella Carollo; Stephen Hamer; Wolfram Kollatschny; Davor Krajnović; Raffaella Anna Marino; Johan Richard; Geneviève Soucail; Peter M. Weilbacher; Lutz Wisotzki

doi:10.1051/0004-6361/201731877

Ionised gas structure of 100 kpc in an over-dense region of the galaxy group COSMOS-Gr30 at z ~ 0.7

Benoît Epinat, Thierry Contini, Hayley Finley, Leindert Boogaard, Adrien Guérou, Jarle Brinchmann, David Carton, Léo Michel-Dansac, Roland Bacon, Sebastiano Cantalupo, Marcella Carollo, Stephen Hamer, Wolfram Kollatschny, Davor Krajnović, Raffaella Anna Marino, Johan Richard, Geneviève Soucail, Peter M. Weilbacher, Lutz Wisotzki

Department of Physics

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Abstract

We report the discovery of a 10 ⁴ kpc ² gaseous structure detected in [O ii]λλ3727, 3729 in an over-dense region of the COSMOS-Gr30 galaxy group at z ∼ 0.725 with deep MUSE Guaranteed Time Observations. We estimate the total amount of diffuse ionised gas to be of the order of (∼5 ± 3) × 10 ¹⁰ M _- and explore its physical properties to understand its origin and the source(s) of the ionisation. The MUSE data allow the identification of a dozen group members that are embedded in this structure through emission and absorption lines. We extracted spectra from small apertures defined for both the diffuse ionised gas and the galaxies. We investigated the kinematics and ionisation properties of the various galaxies and extended gas regions through line diagnostics (R23, O32, and [O iii]/Hβ) that are available within the MUSE wavelength range. We compared these diagnostics to photo-ionisation models and shock models. The structure is divided into two kinematically distinct sub-structures. The most extended sub-structure of ionised gas is likely rotating around a massive galaxy and displays filamentary patterns that link some galaxies. The second sub-structure links another massive galaxy that hosts an active galactic nucleus (AGN) to a low-mass galaxy, but it also extends orthogonally to the AGN host disc over ∼ 35 kpc. This extent is likely ionised by the AGN itself. The location of small diffuse regions in the R23 vs. O32 diagram is compatible with photo-ionisation. However, the location of three of these regions in this diagram (low O32, high R23) can also be explained by shocks, which is supported by their high velocity dispersions. One edge-on galaxy shares the same properties and may be a source of shocks. Regardless of the hypothesis, the extended gas seems to be non-primordial. We favour a scenario where the gas has been extracted from galaxies by tidal forces and AGN triggered by interactions between at least the two sub-structures.

Original language	English
Article number	A40
Pages (from-to)	1-21
Number of pages	21
Journal	Astronomy & Astrophysics
Volume	609
Early online date	5 Jan 2018
DOIs	https://doi.org/10.1051/0004-6361/201731877
Publication status	Published - 5 Jan 2018

Bibliographical note

21 pages, 12 figures, 3 tables, accepted for publication in A&A (27 October 2017)

Keywords

astro-ph.GA
Galaxies: evolution
Galaxies: kinematics and dynamics
Galaxies: groups: general
Intergalactic medium
Galaxies: interactions
Galaxies: high-redshift

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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10.1051/0004-6361/201731877Licence: CC BY

Cite this

Epinat, B., Contini, T., Finley, H., Boogaard, L., Guérou, A., Brinchmann, J., Carton, D., Michel-Dansac, L., Bacon, R., Cantalupo, S., Carollo, M., Hamer, S., Kollatschny, W., Krajnović, D., Marino, R. A., Richard, J., Soucail, G., Weilbacher, P. M., & Wisotzki, L. (2018). Ionised gas structure of 100 kpc in an over-dense region of the galaxy group COSMOS-Gr30 at z ~ 0.7. Astronomy & Astrophysics, 609, 1-21. Article A40. https://doi.org/10.1051/0004-6361/201731877

Epinat, B, Contini, T, Finley, H, Boogaard, L, Guérou, A, Brinchmann, J, Carton, D, Michel-Dansac, L, Bacon, R, Cantalupo, S, Carollo, M, Hamer, S, Kollatschny, W, Krajnović, D, Marino, RA, Richard, J, Soucail, G, Weilbacher, PM & Wisotzki, L 2018, 'Ionised gas structure of 100 kpc in an over-dense region of the galaxy group COSMOS-Gr30 at z ~ 0.7', Astronomy & Astrophysics, vol. 609, A40, pp. 1-21. https://doi.org/10.1051/0004-6361/201731877

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title = "Ionised gas structure of 100 kpc in an over-dense region of the galaxy group COSMOS-Gr30 at z ~ 0.7",

abstract = "We report the discovery of a 10 4 kpc 2 gaseous structure detected in [O ii]λλ3727, 3729 in an over-dense region of the COSMOS-Gr30 galaxy group at z ∼ 0.725 with deep MUSE Guaranteed Time Observations. We estimate the total amount of diffuse ionised gas to be of the order of (∼5 ± 3) × 10 10 M - and explore its physical properties to understand its origin and the source(s) of the ionisation. The MUSE data allow the identification of a dozen group members that are embedded in this structure through emission and absorption lines. We extracted spectra from small apertures defined for both the diffuse ionised gas and the galaxies. We investigated the kinematics and ionisation properties of the various galaxies and extended gas regions through line diagnostics (R23, O32, and [O iii]/Hβ) that are available within the MUSE wavelength range. We compared these diagnostics to photo-ionisation models and shock models. The structure is divided into two kinematically distinct sub-structures. The most extended sub-structure of ionised gas is likely rotating around a massive galaxy and displays filamentary patterns that link some galaxies. The second sub-structure links another massive galaxy that hosts an active galactic nucleus (AGN) to a low-mass galaxy, but it also extends orthogonally to the AGN host disc over ∼ 35 kpc. This extent is likely ionised by the AGN itself. The location of small diffuse regions in the R23 vs. O32 diagram is compatible with photo-ionisation. However, the location of three of these regions in this diagram (low O32, high R23) can also be explained by shocks, which is supported by their high velocity dispersions. One edge-on galaxy shares the same properties and may be a source of shocks. Regardless of the hypothesis, the extended gas seems to be non-primordial. We favour a scenario where the gas has been extracted from galaxies by tidal forces and AGN triggered by interactions between at least the two sub-structures. ",

keywords = "astro-ph.GA, Galaxies: evolution, Galaxies: kinematics and dynamics, Galaxies: groups: general, Intergalactic medium, Galaxies: interactions, Galaxies: high-redshift",

author = "Beno{\^i}t Epinat and Thierry Contini and Hayley Finley and Leindert Boogaard and Adrien Gu{\'e}rou and Jarle Brinchmann and David Carton and L{\'e}o Michel-Dansac and Roland Bacon and Sebastiano Cantalupo and Marcella Carollo and Stephen Hamer and Wolfram Kollatschny and Davor Krajnovi{\'c} and Marino, {Raffaella Anna} and Johan Richard and Genevi{\`e}ve Soucail and Weilbacher, {Peter M.} and Lutz Wisotzki",

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doi = "10.1051/0004-6361/201731877",

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T1 - Ionised gas structure of 100 kpc in an over-dense region of the galaxy group COSMOS-Gr30 at z ~ 0.7

AU - Epinat, Benoît

AU - Contini, Thierry

AU - Finley, Hayley

AU - Boogaard, Leindert

AU - Guérou, Adrien

AU - Brinchmann, Jarle

AU - Carton, David

AU - Michel-Dansac, Léo

AU - Bacon, Roland

AU - Cantalupo, Sebastiano

AU - Carollo, Marcella

AU - Hamer, Stephen

AU - Kollatschny, Wolfram

AU - Krajnović, Davor

AU - Marino, Raffaella Anna

AU - Richard, Johan

AU - Soucail, Geneviève

AU - Weilbacher, Peter M.

AU - Wisotzki, Lutz

N1 - 21 pages, 12 figures, 3 tables, accepted for publication in A&A (27 October 2017)

PY - 2018/1/5

Y1 - 2018/1/5

N2 - We report the discovery of a 10 4 kpc 2 gaseous structure detected in [O ii]λλ3727, 3729 in an over-dense region of the COSMOS-Gr30 galaxy group at z ∼ 0.725 with deep MUSE Guaranteed Time Observations. We estimate the total amount of diffuse ionised gas to be of the order of (∼5 ± 3) × 10 10 M - and explore its physical properties to understand its origin and the source(s) of the ionisation. The MUSE data allow the identification of a dozen group members that are embedded in this structure through emission and absorption lines. We extracted spectra from small apertures defined for both the diffuse ionised gas and the galaxies. We investigated the kinematics and ionisation properties of the various galaxies and extended gas regions through line diagnostics (R23, O32, and [O iii]/Hβ) that are available within the MUSE wavelength range. We compared these diagnostics to photo-ionisation models and shock models. The structure is divided into two kinematically distinct sub-structures. The most extended sub-structure of ionised gas is likely rotating around a massive galaxy and displays filamentary patterns that link some galaxies. The second sub-structure links another massive galaxy that hosts an active galactic nucleus (AGN) to a low-mass galaxy, but it also extends orthogonally to the AGN host disc over ∼ 35 kpc. This extent is likely ionised by the AGN itself. The location of small diffuse regions in the R23 vs. O32 diagram is compatible with photo-ionisation. However, the location of three of these regions in this diagram (low O32, high R23) can also be explained by shocks, which is supported by their high velocity dispersions. One edge-on galaxy shares the same properties and may be a source of shocks. Regardless of the hypothesis, the extended gas seems to be non-primordial. We favour a scenario where the gas has been extracted from galaxies by tidal forces and AGN triggered by interactions between at least the two sub-structures.

AB - We report the discovery of a 10 4 kpc 2 gaseous structure detected in [O ii]λλ3727, 3729 in an over-dense region of the COSMOS-Gr30 galaxy group at z ∼ 0.725 with deep MUSE Guaranteed Time Observations. We estimate the total amount of diffuse ionised gas to be of the order of (∼5 ± 3) × 10 10 M - and explore its physical properties to understand its origin and the source(s) of the ionisation. The MUSE data allow the identification of a dozen group members that are embedded in this structure through emission and absorption lines. We extracted spectra from small apertures defined for both the diffuse ionised gas and the galaxies. We investigated the kinematics and ionisation properties of the various galaxies and extended gas regions through line diagnostics (R23, O32, and [O iii]/Hβ) that are available within the MUSE wavelength range. We compared these diagnostics to photo-ionisation models and shock models. The structure is divided into two kinematically distinct sub-structures. The most extended sub-structure of ionised gas is likely rotating around a massive galaxy and displays filamentary patterns that link some galaxies. The second sub-structure links another massive galaxy that hosts an active galactic nucleus (AGN) to a low-mass galaxy, but it also extends orthogonally to the AGN host disc over ∼ 35 kpc. This extent is likely ionised by the AGN itself. The location of small diffuse regions in the R23 vs. O32 diagram is compatible with photo-ionisation. However, the location of three of these regions in this diagram (low O32, high R23) can also be explained by shocks, which is supported by their high velocity dispersions. One edge-on galaxy shares the same properties and may be a source of shocks. Regardless of the hypothesis, the extended gas seems to be non-primordial. We favour a scenario where the gas has been extracted from galaxies by tidal forces and AGN triggered by interactions between at least the two sub-structures.

KW - astro-ph.GA

KW - Galaxies: evolution

KW - Galaxies: kinematics and dynamics

KW - Galaxies: groups: general

KW - Intergalactic medium

KW - Galaxies: interactions

KW - Galaxies: high-redshift

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U2 - 10.1051/0004-6361/201731877

DO - 10.1051/0004-6361/201731877

M3 - Article

SN - 0004-6361

VL - 609

SP - 1

EP - 21

JO - Astronomy & Astrophysics

JF - Astronomy & Astrophysics

M1 - A40

ER -

Ionised gas structure of 100 kpc in an over-dense region of the galaxy group COSMOS-Gr30 at z ~ 0.7

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

Access to Document

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