Image of Alice in Wonderland at the Mad Hatter's tea party You are cordially invited to afternoon tea and biscuits wine and chocolate

Astronomy Tea Talks at Caltech

Mondays, Robinson 106
Tea:  4.00pm
Talk: 4.15pm

Organised by:

2007 - 2008 season:
5 November 2007 Jason Melbourne (Caltech)

"Probing the Decline of Star Formation Since z=1"


Optical and IR surveys have shown a factor of ten decline in the cosmic star formation rate density since z=1.
Explanations have ranged from a decline in triggered bursts such as mergers, to more secular processes such as gas depletion or
quenching. At z=1, the bulk of the cosmic star formation appears to be occurring in luminous infrared galaxies (LIRGs), with star
formation rates in excess of 20 solar masses per year. Locally, LIRGs are very rare and are generally starbursts produced in
mergers of gas rich spirals. At z=1, we have found that the majority of LIRGs are isolated spiral galaxies. While this rules out
major mergers as triggers for the majority of z=1 LIRGs, other processes may contribute such as minor mergers, bar instabilities,
or interactions. Our work, however, suggests that while these processes may be occurring in the distant LIRGs they are also
occurring in the general field population. In fact, we find the bulk of galaxies at z=1 show elevated star formation compared
with today and the decline in star formation since then may simply be a matter of gas depletion.
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Last modified on 20th Jul 2011 by Johan Richard.  

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