SDSS-IV MaNGA: The Spatial Distribution of Star Formation and its Dependence on Mass, Structure and Environment (arXiv:1710.05049v1) 胡 宁 10.18

1.Sample MaNGA DR14 (2791 galaxies) remove IFUs which contain two or more galaxies (153) Five groups: Star forming (1049), composite (435), AGN/LI(N)ER (428) from BPT Low SNR AGN: low SNR in Hb and [OIII] but with integrated SNR > 3 in Ha and [NII] with log(Ha/NII) > 0.47 (22) Lineless galaxies: low SNR in all four lines (719, discarded) Remove edge-on disks with a b/a < 0.3

1494 galaxies: 1016 star forming, 364 composite 114 AGN/LI(N)ER.

Other catalogs Baldry et al. (2006) Environment Density catalog. Yang Group Catalog (Yang et al. 2007,2008,2009,2012) Central and Satellite galaxy classifications, the dark matter halo masses and the group luminosities. Baldry et al. (2006) Environment Density catalog.

Star formation rates Ha SFRs: D4000 SFRs For star forming galaxies in BPT diagram(kennicutt 1998) D4000 SFRs Use Ha SFRs to model the dependence of SSFRs on Dn4000. Use SSFR-D4000 relation to find SFRs for all sample

2.results Global Properties

SSFR profiles at fixex M

In the medium mass bin the satellite have lower SSFR at all radii, but in the cores of the galaxies it appears that the satellites are not as suppressed as the centrals. In the highest mass bin, we see that the satellites have higher SSFRs in their cores and lower SSFRs at high radii.

SSFR Profiles at fixed σ

3.Quenching mechanisms Centrally suppressed galaxies

There is no difference in the fraction of centrally suppressed galaxies at fixed mass between the central and satellite population. This implies that the mechanisms behind the central suppression are independent from environment completely, and depend only on the galaxy's internal properties.

the centrally suppressed galaxies have reduce SSFRs at all radii compared to the unsuppressed galaxies, not just in their cores, suggesting that central suppression leads to external suppression, or at least that if fractional growth is low in the centre of galaxies it will be low in the outskirts.

AGN feedback At all masses, the AGN galaxies are more likely to be centrally suppressed, and in the medium and high mass bins the composites are more likely to be quenched than star forming galaxies as well

Morphological quenching

4.Conclusion SSFR of galaxies decreases with mass and σ revealed the existence of two groups of galaxies: Centrally Suppressed and Unsuppressed. High mass and high σ galaxies are much more likely to have suppressed SSFRs in their cores centrally suppressed galaxies actually have suppressed SSFR at all radii, suggesting that central suppression correlates with the suppression of star formation in the outskirts of the galaxy, or at least that low fractional growth in the centre of galaxies means low growth in the outskirts

At all masses the AGN/LI(N)ER galaxies were more likely to have centrally suppressed SSFRs than star forming galaxies, and that composites were more likely to be suppressed at medium and high masses. High mass-high Sersic and high mass-high dispersion galaxies are predominantly centrally suppressed. a large bulge component stabilises the gas disk and prevents star formation Environmental component in quenching process is not found.