Monday, April 14, 2014
4:15 pm
Cahill, Hameetman Auditorium

Astronomy Tea Talk

The distribution of metals in the z~2.5 circumgalactic medium
Neil Crighton, Swinburne
Observations of the gaseous halos of galaxies (the circumgalactic medium or CGM) are able to constrain important but poorly-understood mechanisms that govern galaxy formation, such as supernovae-driven outflows and gas inflowing along cold-accretion streams. I will present the first results from our group's survey of cool gas in the CGM of Lyman-break selected galaxies at z~2.5, near the peak of the cosmic star formation rate. By comparing the gas absorption features seen towards a background QSO sightline nearby a foreground galaxy to photo-ionization models we measure the metallicity of the gas, which is crucial to determine its origin. Using a new method that includes variations in the shape of the UV radiation illuminating the gas, we derive robust metallicity measurements. We show that metal-enriched gas is found in the CGM up to ~100 kpc from foreground galaxies.
Contact Luca Ricci and Dan Perley lricci@astro.caltech.edu and dperley@astro.caltech.edu at 626-395-2460 and 626-395-3734
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