TY - JOUR
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
UR - http://www.scopus.com/inward/record.url?scp=85040312562&partnerID=8YFLogxK
U2 - 10.1051/0004-6361/201731877
DO - 10.1051/0004-6361/201731877
M3 - Article
VL - 609
SP - 1
EP - 21
JO - Astronomy & Astrophysics
JF - Astronomy & Astrophysics
SN - 0004-6361
M1 - A40
ER -