Spectroscopic follow-up of a cluster candidate at z= 1.45
| Autor: | Rob Ivison, Matt J. Jarvis, Steve Rawlings, D. G. Bonfield, M. G. Watson, Lee Clewley, Garret Cotter, Tony Readhead, Caroline van Breukelen, Chris Simpson |
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| Rok vydání: | 2007 |
| Předmět: |
Physics
Active galactic nucleus 010308 nuclear & particles physics Infrared Hubble Deep Field Astrophysics::High Energy Astrophysical Phenomena media_common.quotation_subject Astronomy and Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics Astrophysics 01 natural sciences Redshift Galaxy Space and Planetary Science Sky 0103 physical sciences Cluster (physics) Astrophysics::Solar and Stellar Astrophysics Astrophysics::Earth and Planetary Astrophysics 010303 astronomy & astrophysics Spectrograph Astrophysics::Galaxy Astrophysics media_common |
| Zdroj: | Monthly Notices of the Royal Astronomical Society. 382:971-984 |
| ISSN: | 0035-8711 |
| DOI: | 10.1111/j.1365-2966.2007.12433.x |
| Popis: | We have obtained deep optical spectroscopic data of the highest-redshift cluster candidate (z ~ 1.4, CVB13) selected by Van Breukelen et al. (2006) in a photometric optical/infrared catalogue of the Subaru XMM-Newton Deep Field. The data, which comprise 104 targeted galaxies, were taken with the DEep Imaging Multi-Object Spectrograph (DEIMOS) on the Keck 2 telescope and yielded 31 secure redshifts in the range 1.25 10^14 M_sun and it may therefore be termed a cluster. There is an X-ray source at the cluster position which is marginally spatially resolved but whose X-ray spectrum is too hard to be thermal cluster emission. Its origin could be the summed X-ray emission from active galaxies in, and projected onto, the cluster. Serendipitously we have discovered a cluster at z = 1.28 with a mass of > 10^14 M_sun at the same position on the sky, comprising six spectroscopically confirmed cluster galaxies and at least one additional radio source. The selection of CVB13 for the cluster catalogue was evidently aided by the superposition of other, presumably lower-mass, structures, whereas the single cluster at z = 1.28 contained too few galaxies to be isolated by the same algorithm. Given the complicated nature of such structures, caution must be employed when measuring the mass function of putative high-redshift clusters with photometric techniques alone. |
| Databáze: | OpenAIRE |
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