Journal Article

Star formation in galaxies falling into clusters along supercluster-scale filaments

Scott C. Porter, Somak Raychaudhury, Kevin A. Pimbblet and Michael J. Drinkwater

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 388, issue 3, pages 1152-1160
Published in print August 2008 | ISSN: 0035-8711
Published online July 2008 | e-ISSN: 1365-2966 | DOI:
Star formation in galaxies falling into clusters along supercluster-scale filaments

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With the help of a statistical parameter derived from optical spectra, we show that the current star formation rate of a galaxy, falling into a cluster along a supercluster filament, is likely to undergo a sudden enhancement before the galaxy reaches the virial radius of the cluster. From a sample of 52 supercluster-scale filaments of galaxies joining a pair of rich clusters of galaxies within the two-degree Field Redshift Survey region, we find a significant enhancement of star formation, within a narrow range between ∼2 and 3 h−170 Mpc of the centre of the cluster into which the galaxy is falling. This burst of star formation is almost exclusively seen in the fainter dwarf galaxies (MB≥−20). The relative position of the peak does not depend on whether the galaxy is a member of a group or not, but non-group galaxies have on average a higher rate of star formation immediately before falling into a cluster. From the various trends, we conclude that the predominant process responsible for this rapid burst is the close interaction with other galaxies falling into the cluster along the same filament, if the interaction occurs before the gas reservoir of the galaxy gets stripped off due to the interaction with the intracluster medium.

Keywords: galaxies: clusters: general; galaxies: evolution; galaxies: starburst; cosmology: observations; large-scale structure of Universe

Journal Article.  7013 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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