Galaxy and Mass Assembly (GAMA): Demonstrating the Power of WISE in the Study of Galaxy Groups to z < 0.1

Abstract

Combining high-fidelity group characterisation from the Galaxy and Mass Assembly (GAMA) survey and source-tailored z < 0.1 photometry from the WISE survey, we present a comprehensive study of the properties of ungrouped galaxies, compared to 497 galaxy groups (4≤ N FoF ≤ 20) as a function of stellar and halo mass. Ungrouped galaxies are largely unimodal in WISE color, the result of being dominated by star-forming, late-type galaxies. Grouped galaxies, however, show a clear bimodality in WISE color, which correlates strongly with stellar mass and morphology. We find evidence for an increasing earlytype fraction, in stellar mass bins between 10 10 M stellar 10 11 M , with increasing halo mass. Using ungrouped, late-type galaxies with star-forming colors (W2−W3>3), we define a star-forming mainsequence (SFMS), which we use to delineate systems that have moved below the sequence ("quenched" for the purposes of this work). We find that with increasing halo mass, the relative number of latetype systems on the SFMS decreases, with a corresponding increase in early-type, quenched systems at high stellar mass (M stellar > 10 10.5 M ), consistent with mass quenching. Group galaxies with masses M stellar < 10 10.5 M show evidence of quenching consistent with environmentally-driven processes. The stellar mass distribution of late-type, quenched galaxies suggests they may be an intermediate population as systems transition from being star-forming and late-type to the "red sequence". Finally, we use the projected area of groups on the sky to extract groups that are (relatively) compact for their halo mass. Although these show a marginal increase in their proportion of high mass and early-type galaxies compared to nominal groups, a clear increase in quenched fraction is not evident.

Galaxy and Mass Assembly (GAMA): A WISE Study of the Activity of Emission-line Systems in G23

“…The linear fit to the selection of Jarrett et al (2017), which is similar to our sample (except that here the AGNs have been separated from SFs), follows our sequence, especially the high-mass end, which is generally populated by AGNs. The new sequence fit by Cluver et al (2020), based on a sample of isolated SF galaxies, also traces our distribution with a slightly flatter slope. Grootes et al (2013) UV-selected a sample of nearby (z < 0.13) spirals in GAMA that gives a flatter SFR-M * relation.…”

Galaxy and Mass Assembly (GAMA): Mid-infrared properties as tracers of galaxy environment

“…The galaxy properties such as M WISE is derived as a function of W1−W2 color (Cluver et al 2014) and SFR12 WISE and SFR22 WISE are derived using the W3 and W4 luminosities respectively (Cluver et al 2017). We refer the reader to Cluver et al (2014Cluver et al ( , 2020 for a detailed description of the construction of this catalogue.…”

“…The main aim of this paper is to utilize the 2pCFs and MCFs to explore the environmental dependence of WISE band properties in GAMA. We use a set of galaxy samples from the GAMA survey enhanced with mid-IR properties from WISE (Cluver et al 2014(Cluver et al , 2020. Due to its high completeness (> 98.5%) down to r < 19.8, GAMA has been abundantly used for clustering studies (e.g.…”

Insights from spectral stacking on the HI content of cluster galaxies in various environments

“…The step function in the upper limits arises owing to a non-detection in W3 for low-mass galaxies and a non-detection after continuum subtraction in W3 for high-mass galaxies. Also shown for reference are fits to the star formation main sequence by Cluver et al (2020), and Saintonge et al (2016). The black dashed line indicates the quench threshold (Cluver et al, 2020) below which galaxies are not considered to be actively star forming.…”

“…Also shown for reference are fits to the star formation main sequence by Cluver et al (2020), and Saintonge et al (2016). The black dashed line indicates the quench threshold (Cluver et al, 2020) below which galaxies are not considered to be actively star forming.…”