SPT-CL J2040-4451: An SZ-selected galaxy cluster at z = 1.478 with significant ongoing star formation

• Published in: The Astrophysical Journal
• Main Authors: Bayliss, M. B., Ashby, M. L. N., Ruel, J., Brodwin, M., Aird, K. A., Bautz, M. W., Benson, B. A., Bleem, L. E., Bocquet, S., Carlstrom, J. E., Chang, C. L., Cho, H. M., Clocchiatti, A., Crawford, T. M., Crites, A. T., Desai, S., Dobbs, M. A., Dudley, J. P., Foley, R. J., Forman, W. R., George, E. M., Gettings, D., Gladders, M. D., Gonzalez, A. H., De Haan, T., Halverson, N. W., High, F. W., Holder, G. P., Holzapfel, W. L., Hoover, S., Hrubes, J. D., Jones, C., Joy, M., Keisler, R., Knox, L., Lee, A. T., Leitch, E. M., Liu, J., Lueker, M., Luong-Van, D., Mantz, A., Marrone, D. P., Mawatari, K., McDonald, M., McMahon, J. J., Mehl, J., Meyer, S. S., Miller, E. D., Mocanu, L., Mohr, J. J., Montroy, T. E., Murray, S. S., Padin, S., Plagge, T., Pryke, C., Reichardt, C. L., Rest, A., Ruhl, J. E., Saliwanchik, B. R., Saro, A., Sayre, J. T., Schaffer, K. K., Shirokoff, E., Song, J., Stalder, B., Šuhada, R., Spieler, H. G., Stanford, S. A., Staniszewski, Z., Stark, A. A., Story, K., Stubbs, C. W., Van Engelen, A., Vanderlinde, K., Vieira, J. D., Vikhlinin, A., Williamson, R., Zahn, O., Zenteno, A.
• Other Authors: Mcdonald, M., Mcmahon, J. J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2014
• Subjects: galaxies: clusters: individual (SPT-CL J2040-4451); galaxies: distances and redshift; galaxies: evolution; large-scale structure of universe; Astronomy and Astrophysic; Space and Planetary Science; South Pole; South pole
• Online Access: http://hdl.handle.net/11368/2963135; https://doi.org/10.1088/0004-637X/794/1/12; http://iopscience.iop.org/0004-637X/794/1/12/pdf/0004-637X_794_1_12.pdf

SPT-CL J2040−4451—spectroscopically confirmed at z = 1.478—is the highest-redshift galaxy cluster yet discovered via the Sunyaev–Zel’dovich effect. SPT-CL J2040−4451 was a candidate galaxy cluster identified in the first 720 deg2 of the South Pole Telescope Sunyaev–Zel’dovich (SPT-SZ) survey, and has been confirmed in follow-up imaging and spectroscopy. From multi-object spectroscopy with Magellan-I/Baade+IMACS we measure spectroscopic redshifts for 15 cluster member galaxies, all of which have strong [O ii] λλ3727 emission. SPT-CL J2040−4451 has an SZ-measured mass of M500,SZ = 3.2 ± 0.8 × 1014 M h−1 70 , corresponding to M200,SZ = 5.8 ± 1.4 × 1014 M h−1 70 . The velocity dispersion measured entirely from blue star-forming members is σv = 1500 ± 520 km s−1. The prevalence of star-forming cluster members (galaxies with >1.5 M yr−1) implies that this massive, high-redshift cluster is experiencing a phase of active star formation, and supports recent results showing a marked increase in star formation occurring in galaxy clusters at z 1.4. We also compute the probability of finding a cluster as rare as this in the SPT-SZ survey to be >99%, indicating that its discovery is not in tension with the concordance ΛCDM cosmological model.