The implications of the surprising existence of a large, massive CO disk in a distant protocluster
Dannerbauer, H.; Lehnert, M.D.; Emonts, B.; Ziegler, B.; Altieri, B.; De Breuck, C.; Hatch, N.; Kodama, T.; Koyama, Y.; Kurk, J.D.; Matiz, T.; Miley, G.; Narayanan, D.; Norris, R.P.; Overzier, R.; Röttgering, H.J.A.; Sargent, M.; Seymour, N.; Tanaka, M.; Valtchanov, I.; Wylezalek, D.
C. De Breuck
NINA HATCH firstname.lastname@example.org
It is not yet known if the properties of molecular gas in distant protocluster galaxies are significantly affected by their environment as galaxies are in local clusters. Through a deep, 64 h of effective on-source integration with the Australian Telescope Compact Array (ATCA), we discovered a massive, Mmol = 2.0 ± 0.2× 1011 M⊙, extended, ~40 kpc, CO(1–0)-emitting disk in the protocluster surrounding the radio galaxy, MRC 1138−262. The galaxy, at zCO = 2.1478, is a clumpy, massive disk galaxy, M∗ ~ 5 × 1011 M⊙, which lies 250 kpc in projection from MRC 1138−262 and is a known Hα emitter, named HAE229. This source has a molecular gas fraction of ~30%. The CO emission has a kinematic gradient along its major axis, centered on the highest surface brightness rest-frame optical emission, consistent with HAE229 being a rotating disk. Surprisingly, a significant fraction of the CO emission lies outside of the UV/optical emission. In spite of this, HAE229 follows the same relation between star-formation rate and molecular gas mass as normal field galaxies. HAE229 is the first CO (1–0) detection of an ordinary, star-forming galaxy in a protocluster. We compare a sample of cluster members at z > 0.4 thatare detected in low-order CO transitions, with a similar sample of sources drawn from the field. We confirm findings that the CO-luminosity and full-width at half maximum are correlated in starbursts and show that this relation is valid for normal high-z galaxies as well as for those in overdensities. We do not find a clear dichotomy in the integrated Schmidt-Kennicutt relation for protocluster and field galaxies. Our results suggest that environment does not have an impact on the “star-formation efficiency” or the molecular gas content of high-redshift galaxies. Not finding any environmental dependence in these characteristics, especially for such an extended CO disk, suggests that environmentally-specific processes such as ram pressure stripping do not operate efficiently in (proto)clusters.
|Journal Article Type||Article|
|Journal||Astronomy & Astrophysics|
|Peer Reviewed||Peer Reviewed|
|APA6 Citation||Dannerbauer, H., Lehnert, M., Emonts, B., Ziegler, B., Altieri, B., De Breuck, C., …Wylezalek, D. (in press). The implications of the surprising existence of a large, massive CO disk in a distant protocluster. Astronomy and Astrophysics, 608, https://doi.org/10.1051/0004-6361/201730449|
|Keywords||galaxies: clusters: individual: MRC 1138 / 262 ; galaxies: high-redshift ; galaxies: evolution ; galaxies: ISM ; submillimeter: galaxies ; galaxies: individual: HAE229|
|Copyright Statement||Copyright information regarding this work can be found at the following address: http://eprints.nottingh.../end_user_agreement.pdf|
Copyright information regarding this work can be found at the following address: http://eprints.nottingham.ac.uk/end_user_agreement.pdf
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