Insights into Galaxy Evolution from Mid-infrared Wavelengths
| dc.creator | Chary, Ranga-Ram | |
| dc.date | 2006-12-26 | |
| dc.date.accessioned | 2026-07-07T07:37:06Z | |
| dc.date.available | 2026-07-07T07:37:06Z | |
| dc.description | In this paper, I have attempted to highlight key results from deep extragalactic surveys at mid-infrared wavelengths. I discuss advances in our understanding of dust enshrouded star-formation and AGN activity at 0<z<3 from IRAS, ISO and Spitzer. The data seem to indicate that about 70% of the co-moving star-formation rate density at 0.5<z<3 is obscured by dust and that AGN, including obscured sources, account for <20% of the co-moving bolometric luminosity density. There is tentative evidence that the mode of star-formation changes as a function of redshift; star-formation at z~2 is preferentially in massive, ultraluminous infrared galaxies (ULIRGs) while z~1 sources are luminous infrared galaxies (LIRGs) which are about 1 mag fainter than ULIRGs in the near-infrared. This evolution of the star-formation mode, is similar to the evolution of the redshift distribution of X-ray sources as a function of X-ray luminosity and would suggest an extension of the downsizing hypothesis to include both AGN and star-forming galaxies. Measuring dust-enshrouded star-formation at z>3 will become possible only with future facilities like ALMA. Currently, the presence of dust can only be assessed in a small fraction of the youngest starbursts at z>5 by looking for redshifted large equivalent width H_alpha emission in broadband filters like the IRAC 4.5 micron passband. H_alpha to UV ratios in these objects are a tracer of dust extinction and measuring this ratio in GOODS galaxies indicate dust in ~20% of star-forming galaxies at z>5. Finally, implications for reionization based on the measured stellar mass density and star-formation rates of galaxies at these redshifts are discussed. | |
| dc.description | 11 pages, 6 figures, proceedings of "At the Edge of the Universe" conference, Sintra, Portugal, Oct 2006 | |
| dc.identifier | https://arxiv.org/abs/astro-ph/0612736 | |
| dc.identifier | http://arxiv.org/abs/astro-ph/0612736 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/120657 | |
| dc.subject | Astrophysics | |
| dc.title | Insights into Galaxy Evolution from Mid-infrared Wavelengths | |
| dc.type | text |