The Environment of MAMBO Galaxies in the COSMOS field Manuel Aravena F. Bertoldi, C. Carilli, E. Schinnerer, H. J. McCracken, K. M. Menten, M. Salvato NRAO postdoc symposium. Socorro 2009

Outlin e Introduction From starburst to QSOs Starburst galaxies in the early Universe The MAMBO 1.2 mm imaging survey of the COSMOS field Environment of submillimeter galaxies Conclusions & Prospects

Introduction: Evolutionary sequence What is the relation between typical ULIRGs and optically bright QSOs? Observations (e.g. Sanders et al. 1988) and Simulations (Gerritsen 1997). MorphologySpectral Energy Distribution (SED) Flux density (arbitrary units) Wavelength (  m)

Starburst and QSOs in the early Universe SCUBA MAMBO Hubble Deep Field North SCUBA map Hubble Deep Field North Optical image Submillimeter blank-field surveys discovered a population of dusty high-redshift galaxies in which a significant fraction of the stars in the Universe were created. Submillimeter galaxies (SMGs): M star ~ M sun, L ~ L sun, at z~2

Scoville et al. (2007) Total area of 2 square degs. Deep exposures: I~26.5 (mag),  (1.4 GHz) ~ 7  Jy Sensitive census of galaxies, their evolution and density growth up to z=1.5 (a third the age of the Universe, 4.3 Gyr after the Big Bang) The COSMOS field

MAMBO imaging of COSMOS MAMBO = Max-Planck Millimeter Bolometer array on the IRAM 30 m telescope in Granada, Spain An area of 20’x20’ mapped to an rms noise level of 1 mJy per 11’’ beam AzTEC 1.1 mm survey (Scott et al. 2008) Bolocam 1.1 mm survey (Aguirre et al., in prep.) MAMBO 1.2 mm survey (Bertoldi, et al. 2007) Optical coverage Spitzer – shallow coverage

MAMBO imaging of COSMOS Detected: 15 sources >4  significance, 11 of which have radio counterparts 10 sources 3  – 4  significance based on a radio identification Figure. MAMBO 1.2 mm final map. Detected sources are marked with a circle and their respective ID number. Figure. MAMBO 1.2 mm rms noise map.

Environment of submillimeter galaxies What is the ‘fate’ of sub-mm galaxies? Will they end up in the most dense environments ? Massive radio galaxies are typically found in very dense environments up to redshift of ~ 4. Figure. Galaxy cluster. X-rays (blue). Optical view taken with the HST. Radio (red). Small survey areas and low-density of sources (Blain et al. 2002) The largest surveys cover ~ 30’ x 30’ Little is known about their relation with environment (isolated?, in dense environments? )

Environment of submillimeter galaxies To date, few studies has been done to investigate the high-redshift environment of SMGs It is possible to study the local environment of sub-mm galaxies at high-redshift. Need to select objects at redshift similar to that of MAMBO galaxies (redshift ~ ) Study the environment of MAMBO galaxies StarburstQSOQSO in dense environment Starburst/QSO transition scenario If sub-mm galaxies evolve into elliptical galaxies in dense environments, they would show signs of clustering in the epoch they were most abundant (redshift ~ )

Environment of submillimeter galaxies New deep K-band imaging of COSMOS (McCracken et al., submitted) K-band selected catalogue Use BzK criterion to split the sample into: sBzK + pBzK (redshift ~ ) nBzK (redshift <~ 1.4) Efficient method to select galaxies at redshifts : BzK color-color criterion (Daddi et al. 2004) Figure. BzK color-color criterion.

Projected density maps of low- and high-redshift BzK galaxies Densities computed using the 7 th nearest neighbour estimator (Dressler, 1980):, where d 7 is the distance to the 7 th nearest neighbour. Density map of low-redshift BzK galaxiesDensity map of high-redshift BzK galaxies

Consistency check Reliability of our maps Both maps trace mostly the same structures, supporting the reliability of our map. Figure. Background: Density map computed from the K-band selected catalog. Red contours: Density map computed by Scoville et al. (2007) from the COSMOS I-band catalog.

Results Some MAMBO galaxies are located in regions with enhanced density of low-z galaxies Consistent with lensing by foreground galaxies Figure. Distribution of densities at the position of MAMBO galaxies (filled) compared with the field (open). Four MAMBO galaxies are located in overdense environments at high-z

Environment of submillimeter galaxies Figure. BzK true color image of the fields of the four MAMBO galaxies embedded in the most overdense regions of high-redshift galaxies.

How likely is that the association of MAMBO galaxies with these overdensities is produced by chance? Poisson probability of chance association that a significant density peak is found by chance within a distance d from a millimeter source (Downes et al., 1983) : P(d) ~ 1 – exp( -  d 2 n ), where n number density of peaks in the area of the COSMOS MAMBO field (~20’x20’). Answer: Very unlikely. For COSBO-1, P(20”) = 10.4%For COSBO-3, P(20”) < 1e-3% For COSBO-6, P(20”) = 0.25%For COSBO-16, P(20”) = 2.5%

Photometric redshifts Further evidence: Photometric redshifts for galaxies within 20” from the MAMBO galaxy position. K-band selected Figure. Histograms represent the redshift distribution for : High-redshift BzK galaxies (dark-gray ) All galaxies (light-gray) MAMBO galaxies (black entry) Peaks in redshift distribution. Most galaxies at high redshift

More evidence Plateau de Bureau Interferometer in its D-configuration Higher resolution of ~3” Better sensitivity Tentative detection (3  ) of 2 continuum sources with the PdBI at 1.3 mm toward COSBO-6 Integrated 1.3 mm flux over the whole area is 3.7 +\- 0.3 mJy, consistent with the MAMBO 1.2 mm flux of 5.2+\- 1.0 mJy. The flux derived for the central source is consistent with its radio emission, assuming it has a starburst-like SED.

Conclusions & Prospects MAMBO survey of the COSMOS field. We studied the density of high-redshift BzK galaxies around MAMBO galaxies. Four MAMBO sources appear to be located in strong overdensities of red galaxies at high-redshift. Photometric redshifts and millimeter continuum imaging support these results. Spectroscopy with the Keck telescope will be crucial to confirm groups around SMGs Millimeter imaging of the MAMBO sources to locate possible multiple sources Similar studies in other deep fields for statistical analyses (e.g. CDF-S)