arXiv subjects

F. Tabatabaei

Publications and source records attributed to F. Tabatabaei.

22 records · Page 2Linked to original sources

arXiv2012

Cool Dust in the Outer Ring of NGC 1291

We examine Herschel Space Observatory images of one nearby prototypical outer ring galaxy, NGC 1291, and show that the ring becomes more prominent at wavelengths longer than 160um. The mass of cool dust in the ring dominates the total dust mass of the galaxy, accounting for at least 70% of it. The temperature of the emitting dust in the ring (T=19.5+/-0.3K) is cooler than that of the inner galaxy (T=25.7+/-0.7K). We discuss several explanations for the difference in dust temperature, including age and density differences in the stellar populations of the ring versus the bulge.

astro-ph.CO↗

arXiv2010

Cool gas and dust in M33: Results from the Herschel M33 extended survey (HERM33ES)

We present an analysis of the first space-based far-IR-submm observations of M 33, which measure the emission from the cool dust and resolve the giant molecular cloud complexes. With roughly half-solar abundances, M33 is a first step towards young low-metallicity galaxies where the submm may be able to provide an alternative to CO mapping to measure their H$_2$ content. In this Letter, we measure the dust emission cross-section $σ$ using SPIRE and recent CO and \HI\ observations; a variation in $σ$ is present from a near-solar neighborhood cross-section to about half-solar with the maximum being south of the nucleus. Calculating the total H column density from the measured dust temperature and cross-section, and then subtracting the \HI\ column, yields a morphology similar to that observed in CO. The H$_2$/\HI\ mass ratio decreases from about unity to well below 10% and is about 15% averaged over the optical disk. The single most important observation to reduce the potentially large systematic errors is to complete the CO mapping of M 33.

astro-ph.CO↗

arXiv2003

A Phenomenological Model for QSOs

Using LBQS data, it seems that the predictions of the model is confirmed by observations. The behavior of comoving density versus redshift is consistent with LDDE for QSQs. Considering the cosmic evolution of SFR, a unified aspect for origin and evolution of QSOs and ordinary galaxies is implied by this model.

astro-ph↗

arXiv2003

A Phenomenological Model for the Evolution of Proto-Galaxies

The contraction model of Field and Colgate for proto-galaxies, first proposed to describe the observed properties of quasars, is generalized and used to investigate the evolution of galaxies. The LEDA data base for elliptical, spiral, compact and diffuse galaxies is employed and it is shown that the above model is consistent with observational evidences regarding their dynamical evolution, star formation rate and different morphologies.

astro-ph↗