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Title

Galaxy and Mass Assembly: FUV, NUV, ugrizYJHK Petrosian, Kron and Sersic photometry

Author(s)

Hill, David T.;  Kelvin, Lee S.;  Driver, Simon P.;  Robotham, Aaron S. G.;  Cameron, Ewan;  Cross, Nicholas;  Andrae, Ellen;  Baldry, Ivan K.;  Bamford, Steven P.;  Bland-Hawthorn, Joss;  Brough, Sarah;  Conselice, Christopher J.;  Dye, Simon;  Hopkins, Andrew M.;  Liske, Jochen;  Loveday, Jon;  Norberg, Peder;  Peacock, John A.;  Croom, Scott M.;  Frenk, Carlos S.;  Graham, Alister W.;  Jones, D. Heath;  Kuijken, Konrad;  Madore, Barry F.;  Nichol, Robert C.;  Parkinson, Hannah R.;  Phillipps, Steven;  Pimbblet, Kevin A.;  Popescu, Cristina C.;  Prescott, Matthew;  Seibert, Mark;  Sharp, Rob G.;  Sutherland, Will J.;  Thomas, Daniel;  Tuffs, Richard J.;  van Kampen, Elco

Abstract

In order to generate credible 0.1–2 μm spectral energy distributions, the Galaxy and Mass Assembly (GAMA) project requires many gigabytes of imaging data from a number of instruments to be reprocessed into a standard format. In this paper, we discuss the software infrastructure we use, and create self-consistent ugrizYJHK photometry for all sources within the GAMA sample. Using UKIDSS and SDSS archive data, we outline the pre-processing necessary to standardize all images to a common zero-point, the steps taken to correct for the seeing bias across the data set and the creation of gigapixel-scale mosaics of the three 4 × 12 deg2 GAMA regions in each filter. From these mosaics, we extract source catalogues for the GAMA regions using elliptical Kron and Petrosian matched apertures. We also calculate Sérsic magnitudes for all galaxies within the GAMA sample using sigma, a galaxy component modelling wrapper for galfit 3. We compare the resultant photometry directly and also calculate the r-band galaxy luminosity function for all photometric data sets to highlight the uncertainty introduced by the photometric method. We find that (1) changing the object detection threshold has a minor effect on the best-fitting Schechter parameters of the overall population (M*± 0.055 mag, α± 0.014, ϕ*± 0.0005 h3 Mpc−3); (2) there is an offset between data sets that use Kron or Petrosian photometry, regardless of the filter; (3) the decision to use circular or elliptical apertures causes an offset in M* of 0.20 mag; (4) the best-fitting Schechter parameters from total-magnitude photometric systems (such as SDSS modelmag or Sérsic magnitudes) have a steeper faint-end slope than photometric systems based upon Kron or Petrosian measurements; and (5) our Universe’s total luminosity density, when calculated using Kron or Petrosian r-band photometry, is underestimated by at least 15 per cent.

Publication type

Journal article

Research centre

Swinburne University of Technology. Faculty of Information and Communication Technologies. Centre for Astrophysics and Supercomputing

Source

Monthly Notices of the Royal Astronomical Society, Vol. 412, no. 2 (Apr 2011), pp. 765-799

Publication year

2011

FOR Code(s)

0201 Astronomical and Space Sciences

Keyword(s)

Fundamental parameters;  Galaxy and Mass Assembly project;  GAMA;  Image processing;  Photometric techniques;  Surveys

Publisher

Wiley-Blackwell Publishing

ISSN

0035-8711

Publisher URL

http://dx.doi.org/10.1111/j.1365-2966.2010.17950.x

Copyright

Copyright © 2010 The Authors. Journal compilation copyright © 2010 Royal Astronomical Society. The accepted manuscript is reproduced in accordance with the copyright policy of the publisher. The definitive publication is available at www.interscience.wiley.com.

Research Projects

A new approach to understanding galaxy evolution, Australian Research Council grant number DP0557850

Full text

Peer reviewed