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Letter to the Editor
K. Jäger 1,
K.J. Fricke 1,
I. Appenzeller 2,
T. Szeifert 2,4,
J. Heidt 2,
W. Gässler 3,
R. Häfner 3,
W. Hummel 3,
B. Muschielok 3,
H. Nicklas 1,
W. Seifert 2 and
O. Stahl 2
Received 12 August 1999 / Accepted 7 October 1999
We present VLT-observations of a recently detected galaxy cluster candidate in the field of the radio-quiet quasar Q 0307-0015. R-band images and multi-object spectra (MOS) have been obtained during the commissioning phase II of FORS1 in December 1998. The presumed central cluster galaxy shows the typical spectrum and surface brightness profile of an early-type galaxy and has a redshift of z0.396. We measured the redshift of 20 galaxies in the field and found further 11 galaxies with similar redshift implying that we see a galaxy cluster at intermediate z. We estimate the cluster richness to be comparable with Abell class 0-1. The cluster is not physically associated with Q 0307-0015 having a redshift of z0.770. This was to be expected considering the projected distance of 5´ on the sky.
A closer look at the immediate sourrounding of the QSO shows that Q 0307-0015 seems to reside in an unspectacular environment. Neither a definite close companion candidate nor any excess population of faint galaxies can be seen. This is consistent with the finding at low redshift that most radio-quiet QSOs reside in poorer environments than their radio-loud counterparts.
Key words: galaxies: active galaxies: clusters: general galaxies: quasars: individual: Q 0307-0015
* Based on observations made with the VLT UT1, operated on Cerro Paranal (Chile) by the European Southern Observatory (ESO).
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Online publication: November 23, 1999