WenJuan Liu Lei Qian XiaoBo Dong Ning Jiang
Wen-Juan Liu, Lei Qian, Xiao-Bo Dong, Ning Jiang, Paulina Lira, Zheng Cai, Feige Wang, Jinyi Yang, Ting Xiao, and Minjin Kim
Highlights of SDSS J 083803. 68+540642. 0 1. Dwarf LINER Galaxy (Mv = -17. 89 ) 2. An Intermediate-mass BH 3. A peculiar Ringed structure ( thus it may be not evolved by secular process.
MMT spectrum 1. Red color: u-r=2. 4 2. D 4000>1. 5, stellar population age > 1 Gyr 3. FWHM(Ha) = 2814 km/s 4. M_BH = 3. 16 * 10^6 M_sun 5. Eddington ratio: 0. 016
1. No spiral arms; early-type galaxy. 2. A bright bulge component, a weak galactic disk component, and a faint PSF component. 3. Dwarf galaxy: Mv = -17. 8 mag, comparable to -18. 5 mag of LMC; M_star = 4. 45 *10^9 M_sun, derived from the NIR band luminosity. 4. SFR : 0. 15 M_sun/yr, derived from [OII 3727] 5. A circumgalactic ring structure: major axis (15. 6 kpc) and minor axis (11. 4 kpc)
(MMT) 2 D longslit spectrum What powers the large-scale Ha emission line (~10 kpc) for this object: AGN, Post-AGB, star formation, or heating by some kind of shock? 1. AGN can only roughly balance the one required by the broad Ha emission line. 2. For post-AGB, Q is 2. 7 times lower than that required by the extended Ha emission, assuming a covering factor of 4 pi. 3. Shocks usually enhance those low- ionization forbidden lines. 4. In Situ Star Formation Powers the Extended Ha.
Discussion • The kind of galactic rings that are not associated with galactic bars are generally believed to be formed by a violent interaction (collision or merger) and/or the tidal accretion during such an interaction between two galaxies. • It is interesting to think about the following question: How is the IMBH AGN triggered in such a red, old, and (presumably) gas-poor galaxy? • y Summar • In the present work, we carried out a detailed study with its HST images and MMT longslit spectroscopic data as well as the SDSS data. • The analysis of the HST images indicates that J 0838+5406 is an early-type galaxy: the disk is featureless, faint, and of low surface brightness, whereas the bulge is prominent. • the HST images reveal a circumgalactic ring with a 16 kpc diameter.
- Slides: 7