Berlin 2005 – scientific programme

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T: Teilchenphysik

T 501: Kosmische Strahlung VII

T 501.8: Talk

Tuesday, March 8, 2005, 15:45–16:00, TU H105

On Dark Halo Baryons and Duration of Star-Forming Era in Spiral Galaxies — •Ivana Damjanov¹ and Milan Cirkovic^1,2 — ¹Astronomical Observatory, Volgina 7, 11160 Belgrade 74, Serbia and Montenegro — ²Department of Physics, University of Novi Sad, Trg Dositeja Obradovica 4, 21000 Novi Sad, Serbia and Montenegro

We investigate the impact of different models of global gaseous infall onto "normal" spiral disks on their gas consumption time scales. The old idea of Spitzer about the infall from gaseous galactic haloes was revived with the discovery of the low-redshift population of Lymann-alpha absorbers and first steps made in understanding of the transition between the high-redshift intergalactic and the low-redshift predominantly galactic population of QSO absorption systems, as well as improved understanding of the nature of so-called high-velocity clouds. It turns out that large quantities of gas which has not been astrated or has been astrated only weakly are bound to galaxies at later epochs. Such aggregates present a potential reservoir of gas not only for solution of the classical gas consumption puzzle in spiral disks, but also as a fuel for the future star formation. We present results of analyzes performed on the sample of 61 spiral galaxies used by Kennicutt (1998) for studing the form of global star formation law. Adopting the Schmidt star formation law with index n=1.3 (the average value of a sample of observational surveys), we compare the consumption time scales of the galaxies from the sample for two scenarios of their evolution: "naive" model with neither recycling of interstellar gas nor gas infall from galactic haloes, and a more realistic one with parameters that control the recycling and infall of gas.