SDSS-IV MaNGA: the spatial distribution of star formation and its dependence on mass, structure, and environment

Abstract

We study the spatially resolved star formation of 1494 galaxies in the SDSSIV-MaNGA Survey. SFRs are calculated using a two-step process, using H α in star forming regions and D n 4000 in regions identified as AGN/LI(N)ER or lineless. The roles of secular and environmental quenching processes are investigated by studying the dependence of the radial profiles of specific star formation rate on stellar mass, galaxy structure and environment. We report on the existence of 'Centrally Suppressed' galaxies, which have suppressed SSFR in their cores compared to their disks. The profiles of centrally suppressed and unsuppressed galaxies are distibuted in a bimodal way. Galaxies with high stellar mass and core velocity dispersion are found to be much more likely to be centrally suppressed than low mass galaxies, and we show that this is related to morphology and the presence of AGN/LI(N)ER like emission. Centrally suppressed galaxies also display lower star formation at all radii compared to unsuppressed galaxies. The profiles of central and satellite galaxies are also compared, and we find that satellite galaxies experience lower specific star formation rates at all radii than central galaxies. This uniform suppression could be a signal of the stripping of hot halo gas in the process known as strangulation. We find that satellites are not more likely to be suppressed in their cores than centrals, indicating that the core suppression is an entirely internal process. We find no correlation between the local environment density and the profiles of star formation rate surface density.

SDSS-IV MaNGA: spatially resolved star formation histories and the connection to galaxy physical properties

“…This agrees with the low levels of star formation found in many early-type galaxies using UV-optical colours (Yi et al 2005;Kaviraj et al 2007aKaviraj et al , 2008Schawinski et al 2007), which has been attributed to minor mergers (Kaviraj et al 2009). Our results are consistent with Spindler et al (2018) who examined the SSFR radial profiles as a function of stellar mass, Sérsic index and central velocity dispersion. They found that intermediate and high mass galaxies with high velocity dispersion or Sérsic index (i.e.…”

“…Again using MaNGA data, Wang et al (2018) found evidence for strong gradients in spectral indices, indicating insideout growth in massive galaxies (M * > 10 10 M ), but flat gradients in lower mass galaxies. Finally, Spindler et al (2018) measured the SSFR profiles of intermediate and high mass MaNGA galaxies and found that galaxies with high velocity dispersion or Sérsic index (i.e. significant bulges) had centrally suppressed starformation.…”

Spatially resolved signature of quenching in star-forming galaxies

“…This scenario is in agreement with numbers of observational evidences (e.g. Prantzos & Boissier 2000;Gogarten et al 2010;Spindler et al 2018). Indeed, a natural consequence of inside-out growth is that central regions of galactic discs are, on average, older and more metal-rich than the outskirts (e.g.…”

“…The average profile of QG galaxies shows a slow decline towards large radii. As shown in the central panel of Figure 15, the average SFR surface density of the SFs has an exponential profile, and its linear fit shows a slope of −0.67 (consistent with Spindler et al 2018). Instead, the average trend of QGs shows suppression of SFR with respect to the exponential trend of SFs, with a linear fit characterised by a slope of −0.43.…”

The morphology of H αemission in CALIFA galaxies

“…Analyzing a small sample of galaxies in the MaNGA prototype run (P-MaNGA), Li et al (2015) classified the radial profiles of their three diagnostic parameters (Dn4000), EW(Hδ), and EW(Hα)) as either 'centrally quiescent' or 'centrally star forming'. Recently, Spindler et al (2018) investigated the spatial distribution of star formation in a large sample of galaxies of the MaNGA survey (Bundy et al 2015), revealing the existence of two groups of galaxies, which they named 'Centrally Suppressed' and 'Unsuppressed' regarding the radial distribution of their specific star formation rates. Analogously, Medling et al (2018) studied the resolved star formation of a sample of galaxies in the SAMI survey, also finding a split between galaxy populations with centrally concentrated star formation and those with flatter star formation profiles.…”