Galaxy populations in the most distant SPT-SZ clusters

Abstract

We present the first results from a galaxy population study in the highest redshift galaxy clusters identified in the 2500 deg2 South Pole Telescope Sunyaev Zel’dovich effect (SPT-SZ) survey, which is sensitive to M500 ≳ 3 × 1014 M⊙ clusters from z ∼ 0.2 out to the highest redshifts where such massive structures exist. The cluster selection is to first order independent of galaxy properties, making the SPT-SZ sample particularly well suited for cluster galaxy population studies. We carried out a four-band imaging campaign with the Hubble and Spitzer Space Telescopes of the five z ≳ 1.4, S/NSZE > 5 clusters, that are among the rarest most massive clusters known at this redshift. All five clusters show clear overdensities of red galaxies whose colors agree with the initial cluster redshift estimates, although one (SPT-CLJ0607–4448) shows a galaxy concentration much less prominent than the others. The highest redshift cluster in this sample, SPT-CLJ0459–4947 at z ∼ 1.72, is the most distant M500 > 1014 M⊙ cluster discovered thus far through its intracluster medium, and is one of only three known clusters in this mass range at z ≳ 1.7, regardless of selection. Based on UVJ-like photometric classification of quiescent and star-forming galaxies, we find that the quiescent fraction in the cluster central regions (r/r500 < 0.7) is higher than in the field at the same redshift, with corresponding environmental quenching efficiencies typically in the range ∼0.5 − 0.8 for stellar masses log(M/M⊙) > 10.85. We have explored the impact of emission from star formation on the selection of this sample, concluding that all five clusters studied here would still have been detected with S/NSZE> 5, even if they had the same quiescent fraction as measured in the field. Our results thus point towards an efficient suppression of star formation in the central regions of the most massive clusters, occurring already earlier than z ∼ 1.5.

Persistence of the colour–density relation and efficient environmental quenching to z ∼ 1.4

“…In the next section, we will combine these results with N-body simulations and the Ψ convert valued derived here to create estimates of various timescales required to convert a galaxy from star-forming to quiescent after the accretion into a group/cluster environment. Interestingly, the clear persistence of the color-density relation for higher-stellar mass galaxies across the entire redshift range studied here may help to explain the relatively high quiescent fractions found in distant cluster surveys which are predominantly sensitive to galaxies above log(M * /M ⊙ ) > ∼ 10.4 (e.g., Newman et al 2014;Cooke et al 2016;Lee-Brown et al 2017;Strazzullo et al 2019). This persistence is also broadly consistent with the results of van der Burg et al (2013) who studied the quiescent fraction as a function of stellar mass for galaxies inhabiting 10 massive z ∼ 1 clusters drawn from the GCLASS survey.…”

Sunyaev-Zel’dovich detection of the galaxy cluster Cl J1449+0856 at z = 1.99: The pressure profile in uv space

“…That detection is consistent across different observations (Mantz et al 2018) and thus rather unlikely to be a product of noise. Offsets of this amplitude between either the BCG or X-ray peak and the SZ centroid are not unexpected, especially in clusters that are in a unrelaxed state (e.g., Zhang et al 2014) as we would expect Cl1449 to be given its relative youth, and are commonly observed in high-redshift clusters (e.g., Brodwin et al 2016;Strazzullo et al 2019). We perform a Monte Carlo simulation to estimate the significance of this offset (see Appendix B), subtracting the combined astrometric uncertainty of ACA/ALMA and Chandra in quadrature.…”

Cluster Cosmology Constraints from the 2500 deg2 SPT-SZ Survey: Inclusion of Weak Gravitational Lensing Data from Magellan and the Hubble Space Telescope

“…new spectroscopic measurements (Bayliss et al 2016;Khullar et al 2019;A. Mantz et al 2019, in preparation), two updated high-redshift photo-z measurements with HST (Strazzullo et al 2019), and improved photometric measurements. These improved photometric redshifts are enabled both via the recalibration of our Spitzer redshift models using the new spectroscopic data and by the use of optical data from the Parallel Imager for Southern Cosmology Observations (PISCO), a new imager installed on the Magellan/Clay telescope at Las Campanas Observatory (Stalder et al 2014).…”