Issue |
A&A
Volume 575, March 2015
|
|
---|---|---|
Article Number | A16 | |
Number of page(s) | 9 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361/201425315 | |
Published online | 12 February 2015 |
Building gas rings and rejuvenating S0 galaxies through minor mergers
1
INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio
5,
35122
Padova,
Italy
e-mail:
michela.mapelli@oapd.inaf.it
2
Dipartimento di Fisica e Astronomia Galileo Galilei, University of
Padova, Vicolo dell’Osservatorio
3, 35122
Padova,
Italy
Received: 11 November 2014
Accepted: 19 December 2014
We investigate the effects of minor mergers between an S0 galaxy and a gas-rich satellite galaxy, by means of N-body/smoothed particle hydrodynamics simulations. The satellite galaxy is initially on a nearly parabolic orbit and undergoes several periapsis passages before being completely stripped. In most simulations, a portion of the stripped gas forms a warm dense gas ring in the S0 galaxy, with a radius of ~6–13 kpc and a mass of ~107M⊙. The ring is generally short-lived (≲3 Gyr) if it forms from prograde encounters, while it can live for more than 6 Gyr if it is born from counter-rotating or non-coplanar interactions. The gas ring keeps memory of the initial orbit of the satellite galaxy: it is corotating (counter-rotating) with the stars of the disc of the S0 galaxy, if it originates from prograde (retrograde) satellite orbits. Furthermore, the ring is coplanar with the disc of the S0 galaxy only if the satellite’s orbit was coplanar, while it lies on a plane that is inclined with respect to the disc of the S0 galaxy by the same inclination angle as the orbital plane of the satellite galaxy. The fact that we form polar rings as long-lived and as massive as co-planar rings suggests that rings can form in S0 galaxies even without strong bar resonances. Star formation up to 0.01 M⊙ yr-1 occurs for >6 Gyr in the central parts of the S0 galaxy as a consequence of the interaction. We discuss the implications of our simulations for the rejuvenation of S0 galaxies in the local Universe.
Key words: galaxies: interactions / methods: numerical / galaxies: kinematics and dynamics / galaxies: star formation / galaxies: ISM
© ESO, 2015
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.