Obscured Starburst Activity in High Redshift Clusters and Groups

Details Obscured Starburst Activity in High Redshift Clusters and Groups Obscured Starburst Activity in High Redshift Clusters and Groups

2010-09-14

arxiv.org/abs/1009.2750v1

Astronomy and Astrophysics

Astrophysics

Cosmology and Extragalactic Astrophysics

18 pages, 19 figures, submitted to ApJ

Scientific paper

Using Spitzer-MIPS 24um imaging and Keck spectroscopy we examine the nature of the obscured star forming population in three clusters and three groups at z~0.9. These six systems are components of the Cl1604 supercluster, the largest structure imaged by Spitzer at redshifts near unity. We find that the average density of 24um-detected galaxies within the Cl1604 clusters is nearly twice that of the surrounding field and that this overdensity scales with the cluster's dynamical state. The 24um-bright members often appear optically unremarkable and exhibit only moderate [OII] line emission due to severe obscuration. Their spatial distribution suggests they are an infalling population, but an examination of their spectral properties, morphologies and optical colors indicate they are not simply analogs of the field population that have yet to be quenched. Using stacked composite spectra, we find the 24um-detected cluster and group galaxies exhibit elevated levels of Balmer absorption compared to galaxies undergoing normal, continuous star formation. A similar excess is not observed in field galaxies with equivalent infrared luminosities, indicating a greater fraction of the detected cluster and group members have experienced a burst of star formation in the recent past compared to their counterparts in the field. Our results suggest that gas-rich galaxies at high redshift experience a temporary increase in their star formation activity as they assemble into denser environments. Using HST-ACS imaging we find that disturbed morphologies are common among the 24um-detected cluster and group members and become more prevalent in regions of higher galaxy density. We conclude that mergers are the dominant triggering mechanism responsible for the enhanced star formation found in the Cl1604 groups, while a mix of harassment and mergers are likely driving the activity of the cluster galaxies.

Affiliated with

Also associated with

No associations

Rating

Obscured Starburst Activity in High Redshift Clusters and Groups does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Obscured Starburst Activity in High Redshift Clusters and Groups, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Obscured Starburst Activity in High Redshift Clusters and Groups will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-76244