NIR Mass To Light Radial Profiles In Spiral Galaxies

AGÜERO, M. P.; DIAZ, R. J.

Prague, Czech Republic

Simposio; Galaxy Evolution Across the Hubble Time; 2006

International Astronomical Union

We present the preliminary results of our study of the mass-to-light distribution in spiral galaxies. We show here the detailed near infrared (NIR) mass-to-light (M/L) ratios for M 83 and NGC 253, two nearby spiral galaxies with starburst nuclear activity. We used the light profiles determined from 2MASS JHK band archival data. We selected these bands because they are much less affected by the dust distribution and the giant young star complexes of the spiral arms. In order to derive de mass distribution, we have constructed the most complete rotation curve for M 83 from 2D cinematic data of different gaseous components (HII, CO, HI). The high spatial resolution of our Gemini data allows us to determine central region velocities in a few parsecs scale, while a wide field mosaic of HI data extends the cinematic information beyond five times the optical disk of M83. The high resolution Pa velocity field shows a nuclear disk decoupling whereas the outer part of the Rotation Curve implies the presence of a dark matter halo 20 times more massive than optical disk. NGC 253 Rotation Curve yields to a larger M/L ratio than M 83 and other 4 normal spiral galaxies studied by other authors. We intend to construct a database on very detailed NIR M/L distributions and compare them with the previous optical determinations, in order to study the presence and importance of different structural components in the mass distribution of galaxies and their impact on the Tully-Fisher Law.