Ultraviolet number counts of galaxies from Swift UV/Optical Telescope deep imaging of the Chandra Deep Field South

TL;DR

This paper presents deep ultraviolet imaging of the Chandra Deep Field South using Swift UVOT, providing precise galaxy number counts that support models with an evolving galaxy luminosity function.

Contribution

First deep UVOT imaging of the Chandra Deep Field South measuring galaxy counts in multiple UV filters, improving precision over previous HST and GALEX data.

Findings

NUV number counts show a break in slope with high precision.

Results support models with an evolving galaxy luminosity function.

UV counts span from magnitude 21 to 25.

Abstract

Deep Swift UV/Optical Telescope (UVOT) imaging of the Chandra Deep Field South is used to measure galaxy number counts in three near ultraviolet (NUV) filters (uvw2: 1928 A, uvm2: 2246 A, uvw1: 2600 A) and the u band (3645 A). UVOT observations cover the break in the slope of the NUV number counts with greater precision than the number counts by the Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) and the Galaxy Evolution Explorer (GALEX), spanning a range from 21 < m_AB < 25. Number counts models confirm earlier investigations in favoring models with an evolving galaxy luminosity function.