Issue |
A&A
Volume 531, July 2011
|
|
---|---|---|
Article Number | L15 | |
Number of page(s) | 4 | |
Section | Letters | |
DOI | https://doi.org/10.1051/0004-6361/201117190 | |
Published online | 04 July 2011 |
Letter to the Editor
Discovery of a massive X-ray luminous galaxy cluster at z = 1.579⋆
1
European Space Astronomy Centre (ESAC)/ESA, Madrid, Spain
e-mail: jsantos@sciops.esa.int
2
Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße, 85748 Garching, Germany
3
European Southern Observatory, Karl-Schwarzschild Strasse 2, 85748 Garching, Germany
4
INAF-Osservatorio Astronomico di Trieste, via Tiepolo 11, 34133 Trieste, Italia
5
Departamento de Astronomía y Astrofísica, Pontificia Universidad Católica de Chile, Casilla 306, Santiago 22, Chile
6
Astrophysikalisches Institut Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam, Germany
7
CEASaclay, Service d’Astrophysique, L’Orme des Merisiers, Bât. 709, 91191 Gif-sur-Yvette Cedex, France
Received: 4 May 2011
Accepted: 30 May 2011
We report on the discovery of a very distant galaxy cluster serendipitously detected in the archive of the XMM-Newton mission, within the scope of the XMM-Newton Distant Cluster Project (XDCP). XMMUJ0044.0-2033 was detected at a high significance level (5σ) as a compact, but significantly extended source in the X-ray data, with a soft-band flux f(r < 40″) = (1.5 ± 0.3) × 10-14 erg s-1 cm2. Optical/NIR follow-up observations confirmed the presence of an overdensity of red galaxies matching the X-ray emission. The cluster was spectroscopically confirmed to be at z = 1.579 using ground-based VLT/FORS2 spectroscopy. The analysis of the I − H colour − magnitude diagram shows a sequence of red galaxies with a colour range [3.7 < I − H < 4.6] within 1′ from the cluster X-ray emission peak. However, the three spectroscopic members (all with complex morphology) have significantly bluer colours relative to the observed red-sequence. In addition, two of the three cluster members have [OII] emission, indicative of on-going star formation. Using the spectroscopic redshift we estimated the X-ray bolometric luminosity, Lbol,40″ ~ 5.8 × 1044 erg s-1, implying a massive galaxy cluster. This places XMMU J0044.0-2033 at the forefront of massive distant clusters, closing the gap between lower redshift systems and recently discovered proto- and low-mass clusters at z > 1.6.
Key words: galaxies: clusters: individual: XMMUJ0044.0-2033 / galaxies: high-redshift / X-rays: galaxies: clusters
This work is based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and the USA (NASA); and on observations carried out using the New Technology Telescope and the Very Large Telescope at the La Silla Paranal Observatory, under Program IDs 079.A-0634(B), 081.A-0312(A) and 084.A-0844(A).
© ESO, 2011
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