Ned-allsky

Fabrizio Arrigoni - MPIA - Shedding Light on the Properties of the Circum/Inter-galactic Gas

November
5
S M T W T F S

Giant (100 kpc) and luminous Lyman-alpha nebulae are observed at high redshift around high-redshift radio galaxies (HZRGs), QSOs, and in a population known as Lyman-alpha blob (LABs). There is a growing body of evidence that all of these phenomenon are somehow related, although the mechanism powering their emission is poorly understood. I will present the first results of an ongoing narrow-band imaging survey for diffuse Ly-alpha emission around z ~ 2 quasars, including the discovery of two of the largest Ly-a nebulae known, with emission extending out to ~ 500 kpc into the cosmic web. Observations of high-ionization emission lines like HeII (1640A) and CIV (1549A) provide important diagnostics of physical conditions in these nebulae, and clues to the mechanism that power them. I will present sensitive observations of these emission lines, for a giant Ly-a nebula around a quasar, as well as from deep observations of a sample of 13 Ly-alpha blobs. I will show how photoionization models can be used to interpret such observations. Future deep observations with sensitive IFU instruments (VLT/MUSE and KCWI) will revolutionize the study of such nebulae, allowing the detection of multiple diagnostic lines, which will provide important constraints on the physical nature of circum/inter-galactic gas.

Date: November 5th, 2014
Location: MR LCR