GeminiFocus 2014 Year in Review | Page 9

done in a quite different way, so the jury is still out. galaxies over the past 10 billion years”, Monthly Notices of the Royal Astronomical Society, 427: 550, 2012 The Next Steps: Hubble and the GOGREEN Survey Lidman, C., et al., ”The importance of major mergers in the build up of stellar mass in brightest cluster galaxies at z = 1”, Monthly Notices of the Royal Astronomical Society, 433: 825, 2013 Our team is taking steps to better understand the quenching process in distant clusters. We have recently been awarded time to take H-alpha images of the GCLASS clusters with the Hubble Space Telescope (HST). With HST’s resolution we should be able to not only resolve the star-forming disks in cluster galaxies, but also see if they really have been stripped by the intracluster gas. Even more exciting is the recent start of the GOGREEN (Gemini Observations of Galaxies in Rich Early ENvironments) survey. This 440 hour program is one of the new Gemini Large and Long programs and will obtain spectra for ~1000 cluster and group galaxies at 1.0 < z < 1.5 using the recently-upgraded Hamamatsu chips on both GMOS South and soon on GMOS North. GOGREEN will go much deeper than GCLASS and allow us to access higher-redshift clusters, as well as much lower-mass galaxies. This should allow us to better understand how galaxies of different masses are affected by their environments, as well as whether the whole process changes over cosmic time. GOGREEN observations are slated for completion in 2017, and we look forward to summarizing those results in a future GeminiFocus article. References Biviano, A.; Katgert, P.; Thomas, T.; Adami, C., ”The ESO nearby Abell cluster survey”, Astronomy & Astrophysics, 387: 8, 2002 Haines, C., et al., ”LoCuSS: The steady decline and slow quenching of star formation in cluster galaxies over the last four billion years”, The Astrophysical Journal, 775: 126, 2013 Lidman, C., et al., ”Evidence for significant growth in the stellar mass of brightest cluster January 2015 Muzzin, A., et al., ”The phase space and stellar populations of cluster galaxies at z ~ 1: simultaneous constraints on the location and timescale of satellite quenching”, The Astrophysical Journal, 796: 65, 2014 Muzzin, A., et al., ”The Gemini CLuster Astrophysics Spectroscopic Survey (GCLASS): the role of environment and self-regulation in galaxy evolution at z ~ 1“, The Astrophysical Journal, 746: 188, 2012 Noble, A., Webb, T., Muzzin, A., Wilson, G., Yee, H., van der