Dissipation and Extra Light in Galactic Nuclei. II. "Cusp" Ellipticals

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dc.contributor.utaustinauthorKormendy, Johnen_US
dc.creatorHopkins, Philip F.en_US
dc.creatorCox, Thomas J.en_US
dc.creatorDutta, Suvendra N.en_US
dc.creatorHernquist, Larsen_US
dc.creatorKormendy, Johnen_US
dc.creatorLauer, Tod R.en_US
dc.date.accessioned2016-10-28T19:37:49Z
dc.date.available2016-10-28T19:37:49Z
dc.date.issued2009-03en_US
dc.description.abstractWe study the origin and properties of "extra" or "excess" central light in the surface brightness profiles of cusp or power-law elliptical galaxies. Dissipational mergers give rise to two-component profiles: an outer profile established by violent relaxation acting on stars already present in the progenitor galaxies prior to the final stages of the merger, and an inner stellar population comprising the extra light, formed in a compact central starburst. By combining a large set of hydrodynamical simulations with data that span a broad range of profiles at various masses, we show that observed cusp ellipticals appear consistent with the predicted "extra light" structure, and we use our simulations to motivate a two-component description of the observations that allows us to examine how the properties and mass of this component scale with, e. g., the mass, gas content, and other properties of the galaxies. We show how to robustly separate the physically meaningful extra light and outer, violently relaxed profile, and demonstrate that the observed cusps and "extra light" are reliable tracers of the degree of dissipation in the spheroid-forming merger. We show that the typical degree of dissipation is a strong function of stellar mass, roughly tracing the observed gas fractions of disks of the same mass over the redshift range z similar to 0-2. We demonstrate a correlation between the strength of this component and effective radius at fixed mass, in the sense that systems with more dissipation are more compact, sufficient to explain the discrepancy in the maximum phase-space and mass densities of ellipticals and their progenitor spirals. We show that the outer shape of the light profile in simulated and observed systems (when fit to properly account for the central light) does not depend on mass, with a mean outer Sersic index similar to 2.5. We also explore how this relates to, e. g., the shapes, kinematic properties, and stellar population gradients of ellipticals. Extra light contributes to making remnants rounder and diskier, and imprints stellar population gradients. Simulations with the gas content needed to match observed surface brightness profiles reproduce the observed age, metallicity, and color gradients of cusp ellipticals, and we make predictions for how these can be used as tracers of the degree of dissipation in spheroid Formation.en_US
dc.description.departmentAstronomyen_US
dc.description.sponsorshipen_US
dc.identifierdoi:10.15781/T2S756N6D
dc.identifier.citationHopkins, Philip F., Thomas J. Cox, Suvendra N. Dutta, Lars Hernquist, John Kormendy, and Tod R. Lauer. "Dissipation and Extra Light in Galactic Nuclei. II." The Astrophysical Journal Supplement Series, Vol. 181, No. 1 (Mar., 2009): 135.en_US
dc.identifier.doi10.1088/0067-0049/181/1/135en_US
dc.identifier.issn0067-0049en_US
dc.identifier.urihttp://hdl.handle.net/2152/43085
dc.language.isoEnglishen_US
dc.relation.ispartofen_US
dc.relation.ispartofserialAstrophysical Journal Supplement Seriesen_US
dc.rightsAdministrative deposit of works to Texas ScholarWorks: This works author(s) is or was a University faculty member, student or staff member; this article is already available through open access or the publisher allows a PDF version of the article to be freely posted online. The library makes the deposit as a matter of fair use (for scholarly, educational, and research purposes), and to preserve the work and further secure public access to the works of the University.en_US
dc.rights.restrictionOpenen_US
dc.subjectcosmology: theoryen_US
dc.subjectgalaxies: activeen_US
dc.subjectgalaxies: evolutionen_US
dc.subjectgalaxies:en_US
dc.subjectnucleien_US
dc.subjectquasars: generalen_US
dc.subjectearly-type galaxiesen_US
dc.subjectsupermassive black-holesen_US
dc.subjecthubble-space-telescopeen_US
dc.subjectccd surface photometryen_US
dc.subjectdigital sky surveyen_US
dc.subjectsmoothed particleen_US
dc.subjecthydrodynamicsen_US
dc.subjectquasar luminosity functionen_US
dc.subjectspatially-resolveden_US
dc.subjectspectroscopyen_US
dc.subjectultraluminous infrared galaxiesen_US
dc.subjectbrightest clusteren_US
dc.subjectgalaxiesen_US
dc.subjectastronomy & astrophysicsen_US
dc.titleDissipation and Extra Light in Galactic Nuclei. II. "Cusp" Ellipticalsen_US
dc.typeReviewen_US

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