Galaxy Zoo: Clump Scout: clumpy SDSS gal. at z~<0.2

How they formed, and why they are so rare at low redshift, remains unclear. In this paper we identify the largest sample yet of clumpy galaxies (7050) at low redshift using data from the citizen science project Galaxy Zoo: Clump Scout, in which volunteers classified 58550 Sloan Digital Sky Survey (SDSS) galaxies spanning redshift 0.02<z<0.15.

We apply a robust completeness correction by comparing with simulated clumps identified by the same method. Requiring that the ratio of clump to galaxy flux in the SDSS u band be greater than 8% (similar to clump definitions used by other works), we estimate the fraction of local star-forming galaxies hosting at least one clump (fclumpy) to be 3.22_-0.34_^+0.38^%. We also compute the same fraction with a less stringent relative flux cut of 3% (12.68_-0.88_^+1.38^%), as the higher number count and lower statistical noise of this fraction permit finer comparison with future low-redshift clumpy galaxy studies.