期刊
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
卷 430, 期 2, 页码 1158-1170出版社
OXFORD UNIV PRESS
DOI: 10.1093/mnras/sts684
关键词
galaxies: evolution; galaxies: interactions; galaxies: star formation
资金
- STFC
- NOVA fellowship
- Leverhulme Trust
- Agence Nationale de la Recherche [ANR-07-BLAN-0228]
- Science and Technology Facilities Council [ST/J004650/1, ST/F002289/1, ST/I00162X/1, ST/H008519/1, ST/J001422/1, ST/I001166/1, ST/H004548/1, ST/I001573/1] Funding Source: researchfish
- STFC [ST/J001422/1, ST/H004548/1, ST/J004650/1, ST/F002289/1, ST/H008519/1, ST/I00162X/1, ST/I001166/1, ST/I001573/1] Funding Source: UKRI
We use the HiZELS narrow-band H alpha survey in combination with CANDELS, UKIDSS and WIRDS near-infrared imaging, to investigate the morphologies, merger rates and sizes of a sample of H alpha emitting galaxies in the redshift range z = 0.40-2.23, an epoch encompassing the rise to the peak of the star formation rate density. Merger rates are estimated from space- and ground-based imaging using the M-20 coefficient. To account for the increase in the specific star formation rate (sSFR) of the star forming 'main sequence' with redshift, we normalize the star formation rates of galaxies at each epoch to the typical value derived from the H alpha luminosity function. Once this trend in sSFR is removed we see no evidence for an increase in the number density of star-forming galaxies or the merger rate with redshift. We thus conclude that neither is the main driver of the enhanced star-formation rate density at z similar to 1-2, with secular processes such as instabilities within efficiently fuelled, gas-rich discs or multiple minor mergers the most likely alternatives. However, we find that similar to 40-50 per cent of starburst galaxies, those with enhanced specific star formation at their epoch, are major mergers and this fraction is redshift independent. Finally, we find the surprising result that the typical size of a star-forming galaxy of a given mass does not evolve across the redshift range considered, suggesting a universal size-mass relation. Taken in combination, these results indicate a star-forming galaxy population that is statistically similar in physical size, merger rate and mass over the similar to 6 Gyr covered in this study, despite the increase in typical sSFR.
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