Paper detail

The Stacked Thermal SZ Signal of Locally Brightest Galaxies in Planck Full Mission Data: Evidence for Galaxy Feedback?

We use the Planck full mission temperature maps to examine the stacked thermal Sunyaev-Zel'dovich (tSZ) signal of 188042 "locally brightest galaxies'" (LBGs) selected from the Sloan Digital Sky Survey Data Release 7. Our LBG sample closely matches that of Planck Collaboration XI (2013, PCXI) but our analysis differs in several ways. We work directly in terms of physically observable quantities, requiring minimal assumptions about the gas pressure profile. We explicitly model the dust emission from each LBG and simultaneously measure both the stacked tSZ and dust signals as a function of stellar mass $M_*$. There is a small residual bias in stacked tSZ measurements; we measure this bias and subtract it from our results, finding that the effects are non-negligible at the lowest masses in the LBG sample. Finally, we compare our measurements with two pressure profile models, finding that the profile from Battaglia et al. (2012b) provides a better fit to the results than the Arnaud et al. (2010) "universal pressure profile." However, within the uncertainties, we find that the data are consistent with a self-similar scaling with mass --- more precise measurements are needed to detect the relatively small deviations from self-similarity predicted by these models. Consistent with PCXI, we measure the stacked tSZ signal from LBGs with stellar masses down to $\log_{10}(M_*/M_{\odot}) \sim 11.1-11.3$. For lower stellar masses, however, we do not see evidence for a stacked tSZ signal. We note that the stacked dust emission is comparable to, or larger than, the stacked tSZ signal for $\log_{10}(M_*/M_{\odot}) \lesssim 11.3$. Future tSZ analyses with larger samples and lower noise levels should be able to probe deviations from self-similarity and thus provide constraints on models of feedback and the evolution of hot halo gas over cosmic time.