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dc.contributor.authorDey, Arjun
dc.contributor.authorLee, Kyoung-Soo
dc.contributor.authorReddy, Naveen
dc.contributor.authorCooper, Michael
dc.contributor.authorInami, Hanae
dc.contributor.authorHong, Sungryong
dc.contributor.authorGonzalez, Anthony H.
dc.contributor.authorJannuzi, Buell T.
dc.date.accessioned2016-11-03T20:50:15Z
dc.date.available2016-11-03T20:50:15Z
dc.date.issued2016-05-16
dc.identifier.citationSPECTROSCOPIC CONFIRMATION OF A PROTOCLUSTER AT z ≈ 3.786 2016, 823 (1):11 The Astrophysical Journalen
dc.identifier.issn1538-4357
dc.identifier.doi10.3847/0004-637X/823/1/11
dc.identifier.urihttp://hdl.handle.net/10150/621263
dc.description.abstractWe present new observations of the field containing the z = 3.786 protocluster PC 217.96+ 32.3. We confirm that it is one of the largest known and most overdense high-redshift structures. Such structures are rare even in the largest cosmological simulations. We used the Mayall/MOSAIC1.1 imaging camera to image a 1 degrees.2 x 0 degrees.6 area (approximate to 150 x 75 comoving Mpc) surrounding the protocluster's core and discovered 165 candidate Ly alpha emitting galaxies (LAEs) and 788 candidate Lyman Break galaxies (LBGs). There are at least two overdense regions traced by the LAEs, the largest of which shows an areal overdensity in its core (i. e., within a radius of 2.5 comoving Mpc) of 14 +/- 7 relative to the average LAE spatial density ((rho) over bar) in the imaged field. Further, (rho) over bar is twice that derived by other field LAE surveys. Spectroscopy with Keck/DEIMOS yielded redshifts for 164 galaxies (79 LAEs and 85 LBGs); 65 lie at a redshift of 3.785 +/- 0.010. The velocity dispersion of galaxies near the core is sigma = 350 +/- 40 km s(-1), a value robust to selection effects. The overdensities are likely to collapse into systems with present-day masses of > 10(15)M(circle dot) and > 6 x 10(14)M(circle dot) The low velocity dispersion may suggest a dynamically young protocluster. We find a weak trend between narrow-band (Ly alpha) luminosity and environmental density: the Ly alpha luminosity is enhanced on average by 1.35x within the protocluster core. There is no evidence that the Ly alpha equivalent width depends on environment. These suggest that star formation and/or active galactic nucleus (AGN) activity is enhanced in the higher-density regions of the structure. PC. 217.96+ 32.3 is a Coma cluster analog, witnessed in the process of formation.
dc.description.sponsorshipNASA Keck PI Data Award; W. M. Keck Foundation; NASA [1497290, 1520350]; Radcliffe Institute; National Optical Astronomy Observatory (NOAO); Radcliffe Institute for Advanced Study; Institute for Theory and Computation at Harvard Universityen
dc.language.isoenen
dc.publisherIOP PUBLISHING LTDen
dc.relation.urlhttp://stacks.iop.org/0004-637X/823/i=1/a=11?key=crossref.d41a2100946b1e8f0a360bfc6b3b5152en
dc.rights© 2016. The American Astronomical Society. All rights reserved.en
dc.subjectcosmologyen
dc.subjectobservationsen
dc.subjectgalaxiesen
dc.subjectclustersen
dc.subjectindividualen
dc.subjectgalaxies: distances and redshiftsen
dc.subjectgalaxies: evolutionen
dc.subjectgalaxies: formationen
dc.subjectgalaxies: high-redshiften
dc.titleSPECTROSCOPIC CONFIRMATION OF A PROTOCLUSTER AT z ≈ 3.786en
dc.typeArticleen
dc.contributor.departmentUniv Arizona, Steward Observen
dc.identifier.journalThe Astrophysical Journalen
dc.description.collectioninformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.en
dc.eprint.versionFinal published versionen
dc.internal.reviewer-noteAmanda.en
refterms.dateFOA2018-08-14T13:07:33Z
html.description.abstractWe present new observations of the field containing the z = 3.786 protocluster PC 217.96+ 32.3. We confirm that it is one of the largest known and most overdense high-redshift structures. Such structures are rare even in the largest cosmological simulations. We used the Mayall/MOSAIC1.1 imaging camera to image a 1 degrees.2 x 0 degrees.6 area (approximate to 150 x 75 comoving Mpc) surrounding the protocluster's core and discovered 165 candidate Ly alpha emitting galaxies (LAEs) and 788 candidate Lyman Break galaxies (LBGs). There are at least two overdense regions traced by the LAEs, the largest of which shows an areal overdensity in its core (i. e., within a radius of 2.5 comoving Mpc) of 14 +/- 7 relative to the average LAE spatial density ((rho) over bar) in the imaged field. Further, (rho) over bar is twice that derived by other field LAE surveys. Spectroscopy with Keck/DEIMOS yielded redshifts for 164 galaxies (79 LAEs and 85 LBGs); 65 lie at a redshift of 3.785 +/- 0.010. The velocity dispersion of galaxies near the core is sigma = 350 +/- 40 km s(-1), a value robust to selection effects. The overdensities are likely to collapse into systems with present-day masses of > 10(15)M(circle dot) and > 6 x 10(14)M(circle dot) The low velocity dispersion may suggest a dynamically young protocluster. We find a weak trend between narrow-band (Ly alpha) luminosity and environmental density: the Ly alpha luminosity is enhanced on average by 1.35x within the protocluster core. There is no evidence that the Ly alpha equivalent width depends on environment. These suggest that star formation and/or active galactic nucleus (AGN) activity is enhanced in the higher-density regions of the structure. PC. 217.96+ 32.3 is a Coma cluster analog, witnessed in the process of formation.


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