Browsing by Author "More, Surhud"

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    SDSS-IV MaNGA: Cannibalism Caught in the Act-On the Frequency of Occurrence of Multiple Cores in Brightest Cluster Galaxies
    (2022) Hsu, Yun-Hsin; Lin, Yen-Ting; Huang, Song; Nelson, Dylan; Rodriguez-Gomez, Vicente; Lai, Hsuan-Ting; Greene, Jenny; Leauthaud, Alexie; Aragon-Salamanca, Alfonso; Bundy, Kevin; Emsellem, Eric; Merrifield, Michael; More, Surhud; Okabe, Nobuhiro; Rong, Yu; Brownstein, Joel R.; Lane, Richard R.; Pan, Kaike; Schneider, Donald P.
    Although it is generally accepted that massive galaxies form in a two-phased fashion, beginning with a rapid mass buildup through intense starburst activities followed by primarily dry mergers that mainly deposit stellar mass at outskirts, the late time stellar mass growth of brightest cluster galaxies (BCGs), the most massive galaxies in the universe, is still not well understood. Several independent measurements have indicated a slower mass growth rate than predictions from theoretical models. We attempt to resolve the discrepancy by measuring the frequency of BCGs with multiple cores, which serve as a proxy of the merger rates in the central region and facilitate a more direct comparison with theoretical predictions. Using 79 BCGs at z = 0.06-0.15 with integral field spectroscopic data from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) project, we obtain a multiple-core fraction of 0.11 +/- 0.04 at z approximate to 0.1 within an 18 kpc radius from the center, which is comparable to the value of 0.08 +/- 0.04 derived from mock observations of 218 simulated BCGs from the cosmological hydrodynamical simulation IllustrisTNG. We find that most cores that appear close to the BCGs from imaging data turn out to be physically associated systems. Anchoring on the similarity in the multiple-core frequency between the MaNGA and IllustrisTNG, we discuss the mass growth rate of BCGs over the past 4.5 Gyr.
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    Weak-lensing Mass Calibration of ACTPol Sunyaev-Zel'dovich Clusters with the Hyper Suprime-Cam Survey
    (2019) Miyatake, Hironao; Battaglia, Nicholas; Hilton, Matt; Medezinski, Elinor; Nishizawa, Atsushi J.; More, Surhud; Aiola, Simone; Bahcall, Neta; Bond, J. Richard; Calabrese, Erminia; Choi, Steve K.; Devlin, Mark J.; Dunkley, Joanna; Dunner, Rolando; Fuzia, Brittany; Gallardo, Patricio; Gralla, Megan; Hasselfield, Matthew; Halpern, Mark; Hikage, Chiaki; Hill, J. Colin; Hincks, Adam D.; Hlozek, Renee; Huffenberger, Kevin; Hughes, John P.; Koopman, Brian; Kosowsky, Arthur; Louis, Thibaut; Madhavacheril, Mathew S.; McMahon, Jeff; Mandelbaum, Rachel; Marriage, Tobias A.; Maurin, Loic; Miyazaki, Satoshi; Moodley, Kavilan; Murata, Ryoma; Naess, Sigurd; Newburgh, Laura; Niemack, Michael D.; Nishimichi, Takahiro; Okabe, Nobuhiro; Oguri, Masamune; Osato, Ken; Page, Lyman; Partridges, Bruce; Robertson, Naomi; Sehgal, Neelima; Sherwin, Blake; Shirasaki, Masato; Sievers, Jonathan; Sifon, Cristobal; Simon, Sara; Spergel, David N.; Staggs, Suzanne T.; Stein, George; Takada, Masahiro; Trac, Hy; Umetsu, Keiichi; van Engelenl, Alex; Wollack, Edward J.
    We present weak-lensing measurements using the first-year data from the Hyper Suprime-Cam Strategic Survey Program on the Subaru telescope for eight galaxy clusters selected through their thermal Sunyaev-Zel'dovich (SZ) signal measured at 148 GHz with the Atacama Cosmology Telescope Polarimeter experiment. The overlap between the two surveys in this work is 33.8 square degrees, before masking bright stars. The signal-to-noise ratio of individual cluster lensing measurements ranges from 2.2 to 8.7, with a total of 11.1 for the stacked cluster weak-lensing signal. We fit for an average weak-lensing mass distribution using three different profiles, a Navarro-Frenk-White profile, a dark-matter-only emulated profile, and a full cosmological hydrodynamic emulated profile. We interpret the differences among the masses inferred by these models as a systematic error of 10%, which is currently smaller than the statistical error. We obtain the ratio of the SZ-estimated mass to the lensing-estimated mass (the so-called hydrostatic mass bias 1-b) of 0.74(-0.12)(+0.13), which is comparable to previous SZ-selected clusters from the Atacama Cosmology Telescope and from the Planck Satellite. We conclude with a discussion of the implications for cosmological parameters inferred from cluster abundances compared to cosmic microwave background primary anisotropy measurements.