Galaxy and Mass Assembly (GAMA): Exploring the WISE Web in G12

Abstract

We present an analysis of the mid-infrared Wide-field Infrared Survey Explorer (WISE) sources seen within the equatorial GAMA G12 field, located in the North Galactic Cap. Our motivation is to study and characterize the behavior of WISE source populations in anticipation of the deep multiwavelength surveys that will define the next decade, with the principal science goal of mapping the 3D large-scale structures and determining the global physical attributes of the host galaxies. In combination with cosmological redshifts, we identify galaxies from their WISE W1 (3.4 μm) resolved emission, and we also perform a star-galaxy separation using apparent magnitude, colors, and statistical modeling of star counts. The resulting galaxy catalog has ;590,000 sources in 60 deg 2 , reaching a W1 5σ depth of 31 μJy. At the faint end, where redshifts are not available, we employ a luminosity function analysis to show that approximately 27% of all WISE extragalactic sources to a limit of 17.5 mag (31 μJy) are at high redshift, > z 1. The spatial distribution is investigated using two-point correlation functions and a 3D source density characterization at 5 Mpc and 20 Mpc scales. For angular distributions, we find that brighter and more massive sources are strongly clustered relative to fainter sources with lower mass; likewise, based on WISE colors, spheroidal galaxies have the strongest clustering, while late-type disk galaxies have the lowest clustering amplitudes. In three dimensions, we find a number of distinct groupings, often bridged by filaments and superstructures. Using special visualization tools, we map these structures, exploring how clustering may play a role with stellar mass and galaxy type.

A repeating fast radio burst source localized to a nearby spiral galaxy

“…We attribute this emission to that of Hα, which is bright in emission in the GMOS spectra and, at the redshift of the host galaxy, falls within the r image. The total stellar mass of the galaxy has been estimated to be ∼ 10 10 times the mass of the Sun by using the WISE W1 and W2 colours 59 , which provide a more robust estimation given that they are less affected by extinction.…”

H i galaxies with little star formation: an abundance of LIERs

“…Stellar masses are estimated from the stellar mass-to-light (M * /L W 1 ) ratio relation of Cluver et al (2014) where the W1-W2 colour dependence takes into account the morphological dependence on the M/L (see Appendix A for further details). Dwarf galaxies are optically thin systems in terms of their dust properties, therefore the UV light produced by the young and massive stellar populations escapes the galaxy, causing their W2-W3 colour to be similar to passive galaxies (e.g., Jarrett et al 2017).…”

Automated novelty detection in the WISE survey with one-class support vector machines

“…Banerji et al 2013;Jarrett et al 2017). Current parameter space does not allow for a proper distinction between the real and spurious sources within this anomaly group; only a more in-depth analysis with clustering algorithms could reveal more insight on that matter.…”

“…1). We emphasise that currently the WISE database does not provide any reliable extended source identifications nor isophotal magnitudes, except for a small subset (∼500 000) of objects in common with the 2MASS Extended Source Catalogue and for those in some of the GAMA fields Jarrett et al 2017). …”

“…Walker et al 1989;Pollo et al 2010;Jarrett et al 2017). Today's largest photometric datasets, such as SuperCOS-MOS (Hambly et al 2001), WISE (Wright et al 2010), or Pan-STARRS (Chambers et al 2016), contain of the order of a billion catalogued sources each, which means that even now the traditional ways of dealing with the resulting catalogues by direct human inspection are not practicable.…”