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Published June 10, 2015 | Submitted + Published
Journal Article Open

Galaxy Cluster Scaling Relations between Bolocam Sunyaev-Zel'dovich Effect and Chandra X-Ray Measurements


We present scaling relations between the integrated Sunyaev–Zel'dovich effect (SZE) signal, Y_(SZ), its X-ray analogue, Y_X ≡ M_(gas)T_X, and total mass, M_(tot), for the 45 galaxy clusters in the Bolocam X-ray SZ (BOXSZ) sample. All parameters are integrated within r_(2500). Y_(2500) values are measured using SZE data collected with Bolocam, operating at 140 GHz at the Caltech Submillimeter Observatory. The temperature, T_X, and mass, M_(gas,2500), of the intracluster medium are determined using X-ray data collected with Chandra, and M_(tot) is derived from M_(gas) assuming a constant gas mass fraction. Our analysis accounts for several potential sources of bias, including selection effects, contamination from radio point sources, and the loss of SZE signal due to noise filtering and beam-smoothing effects. We measure the Y_(2500)–Y_X scaling to have a power-law index of 0.84 ± 0.07, and a fractional intrinsic scatter in Y_(2500) of (21 ± 7)% at fixed YX, both of which are consistent with previous analyses. We also measure the scaling between Y_2500 and M_2500, finding a power-law index of 1.06 ± 0.12 and a fractional intrinsic scatter in Y_(2500) at fixed mass of (25 ± 9)%. While recent SZE scaling relations using X-ray mass proxies have found power-law indices consistent with the self-similar prediction of 5/3, our measurement stands apart by differing from the self-similar prediction by approximately 5σ. Given the good agreement between the measured Y_(2500)–Y_X scalings, much of this discrepancy appears to be caused by differences in the calibration of the X-ray mass proxies adopted for each particular analysis.

Additional Information

© 2015 The American Astronomical Society. Received 2014 June 11; accepted 2015 April 11; published 2015 June 3. This material is based upon work at the CSO, which, when the data used in this analysis were taken, was operated by the California Institute of Technology under cooperative agreement with the National Science Foundation. Bolocam was constructed and commissioned using funds from NSF/AST-9618798, NSF/AST-0098737, NSF/AST-9980846, NSF/AST-0229008, and NSF/AST-0206158. Bolocam observations were partially supported by the Gordon and Betty Moore Foundation, the Jet Propulsion Laboratory Research and Technology Development Program, as well as the National Science Council of Taiwan grant NSC100-2112-M-001-008-MY3. We acknowledge the assistance of: the Bolocam instrument team: P.A.R. Ade, J.E. Aguirre, J.J. Bock, S.F. Edgington, J. Glenn, A. Goldin, S.R. Golwala, D. Haig, A.E. Lange, G.T. Laurent, P.D. Mauskopf, H.T. Nguyen, P. Rossinot, and J. Sayers; Matt Ferry, who helped collect the data for Abell 1835 and MS 1054.4-0321; the day crew and Hilo staff of the CSO, who provided invaluable assistance during commissioning and data-taking for this survey data set; and Kathy Deniston, Barbara Wertz, and Diana Bisel, who provided effective administrative support at Caltech and in Hilo. This research made extensive use of high performance computing resources at the U.S. Planck Data Center, which is a part of the Infrared Processing and Analysis Center at Caltech. We also thank an anonymous referee for a detailed report that substantially improved the quality of this paper. N.C. was partially supported by a NASA Graduate Student Research Fellowship; J.S. was partially supported by a NASA Graduate Student Research Fellowship, a NASA Postdoctoral Program fellowship, and a Norris Foundation CCAT Postdoctoral Fellowship; A.M. was funded by NSF AST-0838187 and AST-1140019. The work of L.A.M. was carried out at Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA; support for T.M. was provided by NASA through Einstein Fellowship Program grant No. PF0-110077 awarded by the Chandra X-ray Center, which is operated by the Smithsonian Astrophysical Observatory for NASA under contract NAS8-03060, and by a National Research Council Fellowship. E.P. and J.A.S. were partially supported by NASA/NNX07AH59G. K.U. acknowledges partial support from the Academia Sinica Career Development Award. Facilities: CSO, CXO.

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Submitted - 1406.2800v2.pdf


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