Herschel★-ATLAS/GAMA: a census of dust in optically selected galaxies from stacking at submillimetre wavelengths

Abstract

We use the Herschel‐ATLAS survey to conduct the first large‐scale statistical study of the submillimetre properties of optically selected galaxies. Using ∼80 000 r‐band selected galaxies from 126 deg2 of the GAMA survey, we stack into submillimetre imaging at 250, 350 and 500 μ m to gain unprecedented statistics on the dust emission from galaxies at z < 0.35. We find that low‐redshift galaxies account for 5 per cent of the cosmic 250‐μm background (4 per cent at 350 μ m; 3 per cent at 500 μ m), of which approximately 60 per cent comes from ‘blue’ and 20 per cent from ‘red’ galaxies (rest‐frame g−r). We compare the dust properties of different galaxy populations by dividing the sample into bins of optical luminosity, stellar mass, colour and redshift. In blue galaxies we find that dust temperature and luminosity correlate strongly with stellar mass at a fixed redshift, but red galaxies do not follow these correlations and overall have lower luminosities and temperatures. We make reasonable assumptions to account for the contaminating flux from lensing by red‐sequence galaxies and conclude that galaxies with different optical colours have fundamentally different dust emission properties. Results indicate that while blue galaxies are more luminous than red galaxies due to higher temperatures, the dust masses of the two samples are relatively similar. Dust mass is shown to correlate with stellar mass, although the dust‐to‐stellar mass ratio is much higher for low stellar mass galaxies, consistent with the lowest mass galaxies having the highest specific star formation rates. We stack the 250 μ m‐to‐NUV luminosity ratio, finding results consistent with greater obscuration of star formation at lower stellar mass and higher redshift. Submillimetre luminosities and dust masses of all galaxies are shown to evolve strongly with redshift, indicating a fall in the amount of obscured star formation in ordinary galaxies over the last four billion years.

Herschel-ATLAS: the connection between star formation and AGN activity in radio-loud and radio-quiet active galaxies

“…Several methods have been proposed to account for this bias, including the flux measurements in GAMA apertures by Bourne et al (2012). This method explicitly deblends confused sources and divides the blended flux between them using PSF information, so that average flux is conserved and not counted multiple times in the stack.…”

“…This method explicitly deblends confused sources and divides the blended flux between them using PSF information, so that average flux is conserved and not counted multiple times in the stack. We checked for the effects of clustering in our stacks by comparing to the results obtained from average flux measurements in the catalogue given by Bourne et al (2012), for the 1758 objects overlapping between the two samples. Average fluxes for the matched sample are slightly higher using the deblended apertures method compared with our stacking method, which indicates that our method is not biased by the effects of clustering and the results are robust.…”

Galaxy And Mass Assembly (GAMA): the effect of close interactions on star formation in galaxies

“…The 100 µm data come from the H-ATLAS Phase 1 Data Release (Valiante et al, in preparation), which provides Photoconductor Array Camera and Spectrometer (PACS) maps at 100 and 160 µm reduced using SCANAMORPHOS. The GAMA II photometry in the Herschel maps exploits an algorithm developed by Bourne et al 2012 to optimally capture extended flux while accounting for blending in the low-resolution images. This algorithm consists of convolving the 100 µm map with a kernel given by the GAMA r-band-defined aperture smoothed with the 9 arcsec (full width at half-maximum, FWHM) point spread function (PSF) of the PACS 100 µm band.…”

Continuum observations of M 51 and M 83 at 1.1 mm with AzTEC

“…Recently, there have been many papers of the far-IR/submm continuum emission of external galaxies from the Planck and Herschel missions (e.g. Planck Collaboration 2011; Fritz et al 2012;Foyle et al 2013;Magnelli et al 2012;Bourne et al 2012;Rowlands et al 2012;Boselli et al 2012;Smith et al 2012;Cortese et al 2014Cortese et al , 2012Boselli et al 2010;Eales et al 2010;Gordon et al 2010;Roman-Duval et al 2010;Kirkpatrick et al 2014). These papers find, for example, that the dust and stellar masses of galaxies are correlated (Bourne et al 2012;Cortese et al 2012) and that spiral galaxies and dusty early type galaxies have ∼ 10 6 to 10 8 M of dust (Rowlands et al 2012).…”