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A Comparison of Star-forming Clumps and Tidal Tails in Local Mergers in the CCDG Sample and High Redshift Galaxies

Presentation #228.07 in the session “Elliptical and Starburst Galaxies”.

Published onJan 11, 2021
A Comparison of Star-forming Clumps and Tidal Tails in Local Mergers in the CCDG Sample and High Redshift Galaxies

Hubble Space Telescope images of 7 strongly interacting and merging disk galaxies in the local universe observed in the Clusters, Clumps, Dust and Gas in Extreme Star-Forming Galaxies (CCDG) sample have been blurred, dimmed, and re-pixelated to match the observing conditions at high redshift. With these changes, the local galaxies appear similar to high redshift star-forming galaxies: both are clumpy, and the clumps have about the same range of physical size, mass, intrinsic surface brightness, age, and star formation rate at low and high redshift. This is in contrast to complexes in local non-interacting galaxies, which are smaller and less massive than high redshift clumps. The observed clumps also have the same range of surface density, star formation per unit area, and specific star formation rate as high redshift clumps. These similarities, combined with the loss due to cosmological dimming at high redshift of low surface brightness features seen in the local galaxies, such as tidal tails, suggest that some clumpy high-z galaxies that look isolated could really be mergers. We also studied catalogued star clusters in the local galaxies and found that the giant complexes contain star clusters with normal luminosity functions. We infer from this that high redshift clumps contain (unresolved) normal bound clusters also, as a consequence of a hierarchy of star formation. We thank NASA/STScI for grant HST-GO-15649.


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