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SÉMINAIRE DU LERMA
OBSERVATOIRE DE PARIS
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JEUDI 15 mai 2003, à 14h, 77 avenue Denfert Rochereau


77 avenue Denfert Rochereau, Paris 14



Salle de l'Atelier, Observatoire de Paris





Gaseous environment near the active nucleus of Mrk~1 - Kinematics and composition



Amitesh Omar

Raman Research Institute, Bangalore



Résumé : Abstract: We present Giant Meterwave Radio Telescope (GMRT) observations of the HI 21 cm line and Very Large Array (VLA) observations of the OH 18 cm line from the Seyfert 2 galaxy Mrk 1. Based on HI emission morphology, we speculate that the nuclear activities of Mrk 1 are triggered by tidal interactions with a nearby companion. We have detected two-component HI 21 cm line and the OH 18 cm line in absorption toward the nucleus of Mrk 1 at blueshifted velocities with respect to its systemic velocity indicating an outflow of atomic and molecular gas. The higher velocity components of the HI and OH (1667 MHz) absorption lines are blueshifted from the O[III]5007, O[I]6300, and the systemic velocity by ~ 100 km s$^{-1}$, but are consistent with the O[II]3727 velocity. We explain these velocity discrepancies as due to shock ionization of a region which is pushed forward due to shocks in front of the radio nucleus thereby giving a blueshift to HI, OH, and O[II] velocities. The optical depth ratios tau{HI}/tau{OH1667} of both the components of the HI and OH absorption are ~3, indicating their origin in dense molecular clouds.