SDSS-IV MaNGA: Spatially Resolved Star Formation Main Sequence and LI(N)ER Sequence

Abstract

We present our study on the spatially resolved Hα and M * relation for 536 star-forming and 424 quiescent galaxies taken from the MaNGA survey. We show that the star formation rate surface density (Σ SFR ), derived based on the Hα emissions, is strongly correlated with the M * surface density (Σ * ) on kpc scales for starforming galaxies and can be directly connected to the global star-forming sequence. This suggests that the global main sequence may be a consequence of a more fundamental relation on small scales. On the other hand, our result suggests that ∼ 20% of quiescent galaxies in our sample still have star formation activities in the outer region with lower SSFR than typical star-forming galaxies. Meanwhile, we also find a tight correlation between Σ Hα and Σ * for LI(N)ER regions, named the resolved 'LI(N)ER' sequence, in quiescent galaxies, which is consistent with the scenario that LI(N)ER emissions are primarily powered by the hot, evolved stars as suggested in the literature.

SDSS IV MaNGA: Dependence of Global and Spatially Resolved SFR–M∗ Relations on Galaxy Properties

“…In other words, Hα powered by LI(N)ER is directly correlated with the underlying stellar mass. This has been explained as the hot, evolved stars as the dominant mechanism powering the Hα emission in quiescent galaxies (e.g., Belfiore et al 2016;Hsieh et al 2017). Our Figure 3 is also in line with this scenario.…”

“…There is no clear scaling relation between Hα(H II) and M * (global) for the quiescent population. The strong quiescent sequence in the traditional Hα(global)-M * (global) relation is primarily driven by LI(N)ER emissions as shown by our Figure 5 and Hsieh et al (2017).…”

“…Moreover, in the bulge-dominated galaxies, the non-H II contribution is exclusively dominated by LI(N)ER, whereas the three mechanisms all make a certain contribution, but typically lower than LI(N)ER in the high-B/T galaxies, in the diskdominated galaxies. This originates from the fact that the old stellar population, such as post-AGB stars, have become the main source of ionizing photons after star formation has ceased (Yan & Blanton 2012;Singh et al 2013;Belfiore et al 2016;Hsieh et al 2017). As a whole, the rightmost column shows that f non-H II increases from less than a percent for log(M * /M e )<10 to a few to several tens of percent at log(M * /M e )>10.…”

“…Using spatially resolved spectroscopy, recent studies have shown that there also exist a tight correlation between SFR and stellar mass surface density for nearby and distant star-forming galaxies (Nelson et al 2012;Wuyts et al 2013;Cano-Díaz et al 2016;Abdurro'uf & Akiyama 2017;Hsieh et al 2017;Ellison et al 2018). Recently, Hsieh et al (2017) extended the study to the quiescent population using the MaNGA survey (Mapping Nearby Galaxies at APO; Bundy et al 2015) and found that the emission line fluxes, even classified as LI(N)ER, 14 are also correlated with the underlying stellar mass surface density. Therefore, it is essential to separate out the contribution of nonstar-forming regions when measuring the SFR based on emission line methods.…”

Local AGN survey (LASr): I. Galaxy sample, infrared colour selection, and predictions for AGN within 100 Mpc

“…In addition, some of the AGN identifications might be unreliable, in particular if the object has not been optically classified as Seyfert (1900 objects). Most of the latter are optically classified as LINERs which is a controversial class with respect to its AGN nature because also stellar phenomena can produce similar emission line ratios (e.g., StasiÅĎska et al 2008;Cid Fernandes et al 2010Yan & Blanton 2012;Belfiore et al 2016;Hsieh et al 2017). These caveats have to be taken into account when using this compilation of classifications, and, in this work, we use them only for indicative purposes.…”