Large Quasar Groups

Large quasar groups (LQGs) form some of the largest structures in the universe, spanning over 100 Mpc. They are so large that they probably have not been virialized.  One LQG at 1.2<z<1.4, discovered and explored by Roger Clowes and Luis Campusano and collaborators in the 1990s, has become a focus of a series of multi-wavelength investigations ranging from the far ultraviolet to the near infrared.  I am part of a research group which has published a number of papers and has a range of active observing proposals:

Selected Refereed Publications

Clowes, R.G. & Campusano, L.E. 1991, MNRAS, 249, 218, "
A 100-200 MPC group of quasars"

Clowes, R.G. & Campusano, L.E. 1994, MNRAS, 266, 317, "Observations of Quasars in ESO / SERC Field 927"

Graham, M.J., Clowes, R.G. & Campusano, L.E. 1994, MNRAS, 266, 317, "Finding Quasar Superstructures"

Clowes, R.G., Campusano, L.E. & Graham, M.J. 1999, MNRAS, 309, 48, "
Further observations of quasars in ESO/SERC field 927"

Haines, C.P., Clowes, R.G., Campusano, L.E. & Adamson, A.J. 2001, MNRAS, 323, 688, "The galaxy environment of a quasar at z = 1.226: a possible cluster merger"

Söchting, I.K., Clowes, R.G. & Campusano, L.E. 2002, MNRAS, 331, 569, "Quasar environment in the context of large-scale structure at z~0.3"

Williger, G.M., Clowes, R.G., Campusano, L.E. & Graham, M.J. 2002, ApJ, 578, 708, "Large-Scale Structure at z = 1.2 Outlined by Mg II Absorbers"

Söchting, I.K., Clowes, R.G. & Campusano, L.E. 2004, MNRAS, 347, 1241, "Relation of radio-quiet quasars to galaxy clusters at z < 0.3"

Haines, C.P., Clowes, R.G. & Campusano, L.E. 2004, A&A, 421, 157, "Detection of 20-30 h-1 Mpc-scale galaxy structures embedded in 100 h-1 Mpc-scale structures of quasars and MgII absorbers at z>0.8 and z<1.2"

Söchting, I.K., Campusano, L.E., Haines, C.P., Clowes, R.G., Williger, G.M.,
Graham, M.J., Valls-Gabaud, D., Kuhn, O. 2007, "Spectroscopic pencil beam exploration
of a z~0.8 large-scale structure", MNRAS, submitted

Selected Recent Observing Programs

Williger, G.M., Davé, R., Clowes, R.G., Graham, M.G., Haines, C.P., Liske, J. \& Campusano, L.E.,
 2003, HST Cycle 12 program 9887, 27 orbits with STIS, NICMOS and ACS, "A test of the foreground proximity effect at z=1.2"
Status: HST data all taken, being analysed; NOAO KPNO 4m IR spectroscopy clouded out Feb 2004;
2 nights Mar 2005

Williger, G.M., Campusano, L.E., Clowes, R.G., Valls-Gabaud, D., Davé, R., Söchting, I.K., Haines, C.P. & Graham, M.G., 2004, GALEX Cycle 1 program, 60 ksec, "Galaxies and quasars in the largest structures at z~1"
Status: data ~90% taken, being analysed

Campusano, L.E.,  Lopez, S., Haines, C.P. \& Williger, G.M., 2004, ESO Cycle 74 program, VLT/UVES+NTT/SOFI, 31 hours, "Determining the bias between galaxies and CIV (and MgII) absorbers at z=1.2"
Status: data all taken, being analysed

Kuhn, O., Clowes, R. G., Söchting, I.K., 2004, UKIRT UFTI imaging of Q1047+050 (z=1.215),
K 2.0 hrs, J 4.5 hrs
Status: data all taken, being analysed

Valls-Gabaud, D., Clowes, R.G., Haines, C.P., Williger, G.M. & Campusano, L.E., 2004, CFHT/MegaCam 2007a program, 7 hours in rz, "Large-scale galaxy sheets at z=0.8 and z=1.2 and the quasar-galaxy relation toward a Large Quasar Group"
Status: data not taken yet

Williger, G. et al.,  Feb/Dec 2004, Apache Point 3.5m Fabry-Perot imaging of Q1044+059 (z=1.23) tuned
to [OII] at z=1.23 plus I-band, ~3 hours narrowband
Status: data all taken, being analysed

Campusano, L.E. (PI),  Söchting, I.K. (lead UK scientist), Williger, G.M. (lead US scientist), Haines, C.P., Clowes, R.G., Graham, M., Valls-Gabaud, D., 2005, Gemini-South/GMOS 2005a program, 38 hours, "The Galaxy Population Around a Possibly Forming Cluster at z~1.2"
Status: Galaxy overdensity found at z~0.8, See Söchting et al. 2005,
BAAS, 207, 112.03

Clowes, R. G., Kuhn, O., Söchting, I.K., Jan 2005, CTIO 4m Mosaic-II VRIz, 6 half nights
Status: data taken, being reduced and analysed by Clowes and collaborators

Davé, R et al., Jan 2007, Steward Obs. Bok 2.3m+90prime for gi imaging of
GALEX fields, 4 nights (~2 useful)
Status: data being reduced

Haberzettl, L. et al., Feb-Mar 2007, KPNO 2.1m+FLAMINGOS for JK imaging
of GALEX fields, 18.5 nights
Status: data being reduced

Davé, R et al., Feb 2007, Magellan 6.5m+IMACS, multi-slit spectroscopy
of LBGs in GALEX north field, 2 nights
Status: data being reduced

Image of part of Large Quasar Group (16 Mb):

CTIO Big Throughput Camera image (30x30 arcmin) courtesy of Chris Haines, N up, E right

Selected Popular Articles


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