* Astronomy

Blobrana · L

RE: AzTEC-3

Blobrana · L

Ancient gas-rich galaxies found in cosmic crib

Squinting close to the beginning of time, Dominik Riechers, Cornell assistant professor of astronomy, has discovered an association of gas-rich galaxies near the infancy of cosmic time. It's an early epoch - some 12.7 billion years ago - telling a tale that revolves around an exceptionally dusty galaxy called AzTEC-3.
This massive galaxy is the second-most-distant one of its kind known to humanity, Riechers announced at a Feb. 16 lecture at the American Association for the Advancement of Science (AAAS) annual meeting in Chicago.
Read more

Blobrana · L

Title: Star and dust formation activities in AzTEC-3: A starburst galaxy at z = 5.3
Authors: Eli Dwek, Johannes G. Staguhn, Richard G. Arendt, Peter L. Capak, Attila Kovacs, Dominic Benford, Dale Fixsen, Alexander Karim, Samuel Leclercq, Stephen F. Maher, Samuel H. Moseley, Eva Schinnerer, Elmer H. Sharp

Analyses of high-redshift ultraluminous infrared (IR) galaxies traditionally use the observed optical to submillimetre spectral energy distribution (SED) and estimates of the dynamical mass as observational constraints to derive the star formation rate (SFR), the stellar mass, and age of these objects. An important observational constraint neglected in the analysis is the mass of dust giving rise to the IR emission. In this paper we add this constraint to the analysis of AzTEC-3. Adopting an upper limit to the mass of stars and a bolometric luminosity for this object, we construct stellar and chemical evolutionary scenarios, constrained to produce the inferred dust mass and observed luminosity before the associated stellar mass exceeds the observational limit. We find that the model with a Top Heavy IMF provided the most plausible scenario consistent with the observational constraints. In this scenario the dust formed over a period of ~200 Myr, with a SFR of ~500 Msun/yr. These values for the age and SFR in AzTEC-3 are significantly higher and lower, respectively, from those derived without the dust mass constraint. However, this scenario is not unique, and others cannot be completely ruled out because of the prevailing uncertainties in the age of the galaxy, its bolometric luminosity, and its stellar and dust masses. A robust result of our models is that all scenarios require most of the radiating dust mass to have been accreted in molecular clouds. Our new procedure highlights the importance of a multiwavelength approach, and of the use of dust evolution models in constraining the age and the star formation activity and history in galaxies.

Read more (345kb, PDF)