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A z = 2.5 protocluster associated with the radio galaxy MRC 2104-242: star formation and differing mass functions in dense environments

Cooke, E.A.; Hatch, Nina A.; Muldrew, S.I.; Rigby, E.E.; Kurk, J.D.

Authors

E.A. Cooke

Nina A. Hatch

S.I. Muldrew

E.E. Rigby

J.D. Kurk



Abstract

We present results from a narrow-band survey of the field around the high-redshift radio galaxy MRC 2104−242. We have selected Hα emitters in a 7 arcmin2 field and compared the measured number density with that of a field sample at similar redshift. We find that MRC 2104−242 lies in an overdensity of galaxies that is 8.0 ± 0.8 times the average density of a blank field, suggesting it resides in a large-scale structure that may eventually collapse to form a massive cluster. We find that there is more dust obscured star formation in the protocluster galaxies than in similarly selected control field galaxies and there is tentative evidence of a higher fraction of starbursting galaxies in the denser environment. However, on average we do not find a difference between the star formation rate (SFR)–mass relations of the protocluster and field galaxies and so conclude that the SFR of these galaxies at z ∼ 2.5 is governed predominantly by galaxy mass and not the host environment. We also find that the stellar mass distribution of the protocluster galaxies is skewed towards higher masses and there is a significant lack of galaxies at M < 1010M_ within our small field of view. Based on the level of overdensity we expect to find ∼22 star-forming galaxies below 1010M_ in the protocluster and do not detect any. This lack of low-mass galaxies affects the level of overdensity which we detect. If we only consider high-mass (M > 1010.5M_) galaxies, the density of the protocluster field increases to ∼55 times the control field density.

Citation

Cooke, E., Hatch, N. A., Muldrew, S., Rigby, E., & Kurk, J. (2014). A z = 2.5 protocluster associated with the radio galaxy MRC 2104-242: star formation and differing mass functions in dense environments. Monthly Notices of the Royal Astronomical Society, 440(4), https://doi.org/10.1093/mnras/stu522

Journal Article Type Article
Acceptance Date Mar 13, 2014
Publication Date Apr 17, 2014
Deposit Date Sep 28, 2016
Publicly Available Date Sep 28, 2016
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Oxford University Press
Peer Reviewed Peer Reviewed
Volume 440
Issue 4
DOI https://doi.org/10.1093/mnras/stu522
Keywords Cluster galaxies, MRC 2104-242, High-redshift galaxies
Public URL http://eprints.nottingham.ac.uk/id/eprint/37219
Publisher URL http://dx.doi.org/10.1093/mnras/stu522
Copyright Statement Copyright information regarding this work can be found at the following address: http://eprints.nottingham.ac.uk/end_user_agreement.pdf
Additional Information This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2014 The authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

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Copyright Statement
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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