Naveen Reddy (University of Texas)



Radio Luminosity Function for IRAS Selected Galaxies

The luminosity function (LF) for radio sources was determined at 1.4 GHz and 60 micron by correlating infrared sources from the Strauss 1.2 Jy IRAS Redshift Survey with their radio counterparts in the NRAO VLA Sky Survey (NVSS). The sample was limited to those galaxies with known redshift and IRAS 60 micron flux brighter than 2 Jy within two regions of the completed NVSS Sky Survey given by the following coordinates: $4h\leq\alpha<16h$, $\delta\geq30^{\circ}$ and $-40^{\circ}\leq\delta\leq-10^{\circ}$. The radio-far-infrared correlation was derived and accurate positions for IRAS Redshift Survey sources were obtained through the correlation process. Luminosity distributions for 1.4 GHz and 60 micron flux were then constructed.

Comparing our radio luminosity function data with Condon's data, we find a very good correlation between our starburst sample LF with Condon's spiral galaxy LF. We begin to detect the second radio population indicated by Condon to be active galactic nuclei systems. Because of the limits of the sample, small number statistics combines with the lack of identified radio-loud objects to make the radio luminosity function uncertain in the high luminosity regime. Looking at the infrared luminosity, we analyze the 60 micron LF as the sum of two power laws and find a second population of infrared objects that we believe to be massive starburst systems or merger systems.

This work will be expanded upon with the use of a deeper redshift survey (e.g, the ZCAT, LAS CAMPANAS, and KPNO surveys). The ultimate goal will be to go farther in redshift that 0.125 (as in this work) to make statements on the cosmological evolution of galaxies. The results can then be used to determine scenarios of galactic evolution. A more accurate representation of the radio-infrared correlation can be obtained with a greater sample as well. The evolution of the luminosity function with increasing redshift will also be studied. The deeper redshift survey will also provide more data in the high radio and infrared luminosity regimes so that a study of radio-loud and luminous and ultra-luminous infrared galaxies may be carried out. Such an analysis would help to clarify the possiblity of a second infrared population of galaxies.