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The Milky Way has been described as an anaemic spiral, but is its star formation rate (SFR) unusually low when compared to its peers? To answer this question, we define a sample of Milky Way analogues (MWAs) based on stringent cuts on the best literature estimates of non-transient structural features for the Milky Way. This selection yields only 176 galaxies from the whole of the SDSS DR7 spectroscopic sample which have morphological classifications in Galaxy Zoo 2, from which we infer SFRs from two separate indicators. The mean SFRs found are |$\log (\rm {SFR}_{SED}/\rm {M}_{\odot }~\rm {yr}^{-1})=0.53$| with a standard deviation of 0.23 dex from SED fits, and |$\log (\rm {SFR}_{W4}/\rm {M}_{\odot }~\rm {yr}^{-1})=0.68$| with a standard deviation of 0.41 dex from a mid-infrared calibration. The most recent estimate for the Milky Way's SFR of |$\log (\rm {SFR}_{MW}/\rm {M}_{\odot }~\rm {yr}^{-1})=0.22$| fits well within 2 |$\sigma$| of these values, where |$\sigma$| is the standard deviation of each of the SFR indicator distributions. We infer that the Milky Way, while being a galaxy with a somewhat low SFR, is not unusual when compared to similar galaxies. [ABSTRACT FROM AUTHOR]

The connection between quenching mechanisms, which rapidly turn star-forming systems into quiescent, and the properties of the galaxy population remains difficult to discern. In this work we investigate the physical properties of MaNGA and SAMI galaxies at different stages of their star formation history. Specifically, we compare galaxies with signatures of recent quenching (Quenched) – |$\rm H \, \alpha$| in absorption and low Dn (4000) – with the rest of the low star-forming and active population (Retired and Ageing, respectively). The analysis is performed in terms of characteristics such as the total stellar mass, half-light radius, velocity-to-dispersion ratio, metallicity, and environment. We find that the Ageing population comprises a heterogeneous mixture of galaxies, preferentially late-type systems, with diverse physical properties. Retired galaxies, formerly Ageing or Quenched systems, are dominated by early-type high-mass galaxies found both at low and dense environments. Most importantly, we find that recently quenched galaxies are consistent with a population of compact low-mass satellite systems, with higher metallicities than their Ageing analogues. We argue that this is compatible with being quenched after undergoing a star-burst phase induced by environmental processes (e.g. ram pressure). However, we also detect a non-negligible fraction of field central galaxies likely quenched by internal processes. This study highlights that, in order to constrain the mechanisms driving galaxy evolution, it is crucial to distinguish between old (Retired) and recently quenched galaxies, thus requiring at least two estimates of the specific star formation rate over different time-scales. [ABSTRACT FROM AUTHOR]

We present a sample of 91 H  i galaxies with little or no star formation, and discuss the analysis of the integral field unit (IFU) spectra of 28 of these galaxies. We identified H  i galaxies from the H  i Parkes All-Sky Survey Catalog (HICAT) with Wide-field Infrared Survey Explorer (WISE) colours consistent with low specific star formation (<10−10.4 yr−1), and obtained optical IFU spectra with the Wide-Field Spectrograph (WiFeS). Visual inspection of the PanSTARRS, Dark Energy Survey, and Carnegie-Irvine imaging of 62 galaxies reveals that at least 32 galaxies in the sample have low levels of star formation, primarily in arms/rings. New IFU spectra of 28 of these galaxies reveals 3 galaxies with central star formation, 1 galaxy with low-ionization nuclear emission-line regions (LINERs), 20 with extended low-ionization emission-line regions (LIERs), and 4 with high excitation Seyfert (Sy) emission. From the spectroscopic analysis of H  i selected galaxies with little star formation, we conclude that 75 per cent of this population are LINERs/LIERs. [ABSTRACT FROM AUTHOR]