The fundamental manifold of spheroids

Dennis F Zaritsky, Anthony H. Gonzalez, Ann I Zabludoff

Research output: Contribution to journalArticle

75 Citations (Scopus)

Abstract

We present a unifying empirical description of the structural and kinematic properties of all spheroids embedded in dark matter halos. We find that the intracluster stellar spheroidal components of galaxy clusters, which we call cluster spheroids (CSphs) and which are typically 100 times the size of normal elliptical galaxies, lie on a "fundamental plane" as tight as that defined by elliptical galaxies (rms in effective radius of ∼0.07) but having a different slope. The slope, as measured by the coefficient of the log σ term, declines significantly and systematically between the fundamental planes of ellipticals, brightest cluster galaxies (BCGs), and CSphs. We attribute this decline primarily to a continuous change in Me/Le, the mass-to-light ratio within the effective radius re, with spheroid scale. The magnitude of the slope change requires that it arise principally from differences in the relative distributions of luminous and dark matter, rather than from stellar population differences such as in age and metallicity. By expressing the Me/Le term as a function of σ in the simple derivation of the fundamental plane and requiring the behavior of that term to mimic the observed nonlinear relationship between log M e/Le and log σ, we simultaneously fit a two-dimensional manifold to the measured properties of dwarf elliptical and elliptical galaxies, BCGs, and CSphs. The combined data have an rms scatter in log re of 0.114 (0.099 for the combination of ellipticals, BCGs, and CSphs), which is modestly larger than each fundamental plane has alone, but which includes the scatter introduced by merging different studies done in different filters by different investigators. This "fundamental manifold" fits the structural and kinematic properties of spheroids that span a factor of 100 in σ and 1000 in re. While our mathematical form is neither unique nor derived from physical principles, the tightness of the fit leaves little room for improvement by other unification schemes over the range of observed spheroids.

Original languageEnglish (US)
Pages (from-to)725-738
Number of pages14
JournalAstrophysical Journal
Volume638
Issue number2 I
DOIs
StatePublished - Feb 20 2006

Fingerprint

spheroids
elliptical galaxies
kinematics
galaxies
slopes
dark matter
filter
tightness
mass to light ratios
radii
leaves
metallicity
halos
derivation
filters
coefficients

Keywords

  • Galaxies: elliptical and lenticular, cD
  • Galaxies: formation galaxies: fundamental parameters
  • Galaxies: structure

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

The fundamental manifold of spheroids. / Zaritsky, Dennis F; Gonzalez, Anthony H.; Zabludoff, Ann I.

In: Astrophysical Journal, Vol. 638, No. 2 I, 20.02.2006, p. 725-738.

Research output: Contribution to journalArticle

Zaritsky, Dennis F ; Gonzalez, Anthony H. ; Zabludoff, Ann I. / The fundamental manifold of spheroids. In: Astrophysical Journal. 2006 ; Vol. 638, No. 2 I. pp. 725-738.
@article{2b84b197bbea4e7e8fb6dc83d70a163a,
title = "The fundamental manifold of spheroids",
abstract = "We present a unifying empirical description of the structural and kinematic properties of all spheroids embedded in dark matter halos. We find that the intracluster stellar spheroidal components of galaxy clusters, which we call cluster spheroids (CSphs) and which are typically 100 times the size of normal elliptical galaxies, lie on a {"}fundamental plane{"} as tight as that defined by elliptical galaxies (rms in effective radius of ∼0.07) but having a different slope. The slope, as measured by the coefficient of the log σ term, declines significantly and systematically between the fundamental planes of ellipticals, brightest cluster galaxies (BCGs), and CSphs. We attribute this decline primarily to a continuous change in Me/Le, the mass-to-light ratio within the effective radius re, with spheroid scale. The magnitude of the slope change requires that it arise principally from differences in the relative distributions of luminous and dark matter, rather than from stellar population differences such as in age and metallicity. By expressing the Me/Le term as a function of σ in the simple derivation of the fundamental plane and requiring the behavior of that term to mimic the observed nonlinear relationship between log M e/Le and log σ, we simultaneously fit a two-dimensional manifold to the measured properties of dwarf elliptical and elliptical galaxies, BCGs, and CSphs. The combined data have an rms scatter in log re of 0.114 (0.099 for the combination of ellipticals, BCGs, and CSphs), which is modestly larger than each fundamental plane has alone, but which includes the scatter introduced by merging different studies done in different filters by different investigators. This {"}fundamental manifold{"} fits the structural and kinematic properties of spheroids that span a factor of 100 in σ and 1000 in re. While our mathematical form is neither unique nor derived from physical principles, the tightness of the fit leaves little room for improvement by other unification schemes over the range of observed spheroids.",
keywords = "Galaxies: elliptical and lenticular, cD, Galaxies: formation galaxies: fundamental parameters, Galaxies: structure",
author = "Zaritsky, {Dennis F} and Gonzalez, {Anthony H.} and Zabludoff, {Ann I}",
year = "2006",
month = "2",
day = "20",
doi = "10.1086/498672",
language = "English (US)",
volume = "638",
pages = "725--738",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "2 I",

}

TY - JOUR

T1 - The fundamental manifold of spheroids

AU - Zaritsky, Dennis F

AU - Gonzalez, Anthony H.

AU - Zabludoff, Ann I

PY - 2006/2/20

Y1 - 2006/2/20

N2 - We present a unifying empirical description of the structural and kinematic properties of all spheroids embedded in dark matter halos. We find that the intracluster stellar spheroidal components of galaxy clusters, which we call cluster spheroids (CSphs) and which are typically 100 times the size of normal elliptical galaxies, lie on a "fundamental plane" as tight as that defined by elliptical galaxies (rms in effective radius of ∼0.07) but having a different slope. The slope, as measured by the coefficient of the log σ term, declines significantly and systematically between the fundamental planes of ellipticals, brightest cluster galaxies (BCGs), and CSphs. We attribute this decline primarily to a continuous change in Me/Le, the mass-to-light ratio within the effective radius re, with spheroid scale. The magnitude of the slope change requires that it arise principally from differences in the relative distributions of luminous and dark matter, rather than from stellar population differences such as in age and metallicity. By expressing the Me/Le term as a function of σ in the simple derivation of the fundamental plane and requiring the behavior of that term to mimic the observed nonlinear relationship between log M e/Le and log σ, we simultaneously fit a two-dimensional manifold to the measured properties of dwarf elliptical and elliptical galaxies, BCGs, and CSphs. The combined data have an rms scatter in log re of 0.114 (0.099 for the combination of ellipticals, BCGs, and CSphs), which is modestly larger than each fundamental plane has alone, but which includes the scatter introduced by merging different studies done in different filters by different investigators. This "fundamental manifold" fits the structural and kinematic properties of spheroids that span a factor of 100 in σ and 1000 in re. While our mathematical form is neither unique nor derived from physical principles, the tightness of the fit leaves little room for improvement by other unification schemes over the range of observed spheroids.

AB - We present a unifying empirical description of the structural and kinematic properties of all spheroids embedded in dark matter halos. We find that the intracluster stellar spheroidal components of galaxy clusters, which we call cluster spheroids (CSphs) and which are typically 100 times the size of normal elliptical galaxies, lie on a "fundamental plane" as tight as that defined by elliptical galaxies (rms in effective radius of ∼0.07) but having a different slope. The slope, as measured by the coefficient of the log σ term, declines significantly and systematically between the fundamental planes of ellipticals, brightest cluster galaxies (BCGs), and CSphs. We attribute this decline primarily to a continuous change in Me/Le, the mass-to-light ratio within the effective radius re, with spheroid scale. The magnitude of the slope change requires that it arise principally from differences in the relative distributions of luminous and dark matter, rather than from stellar population differences such as in age and metallicity. By expressing the Me/Le term as a function of σ in the simple derivation of the fundamental plane and requiring the behavior of that term to mimic the observed nonlinear relationship between log M e/Le and log σ, we simultaneously fit a two-dimensional manifold to the measured properties of dwarf elliptical and elliptical galaxies, BCGs, and CSphs. The combined data have an rms scatter in log re of 0.114 (0.099 for the combination of ellipticals, BCGs, and CSphs), which is modestly larger than each fundamental plane has alone, but which includes the scatter introduced by merging different studies done in different filters by different investigators. This "fundamental manifold" fits the structural and kinematic properties of spheroids that span a factor of 100 in σ and 1000 in re. While our mathematical form is neither unique nor derived from physical principles, the tightness of the fit leaves little room for improvement by other unification schemes over the range of observed spheroids.

KW - Galaxies: elliptical and lenticular, cD

KW - Galaxies: formation galaxies: fundamental parameters

KW - Galaxies: structure

UR - http://www.scopus.com/inward/record.url?scp=33644775782&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33644775782&partnerID=8YFLogxK

U2 - 10.1086/498672

DO - 10.1086/498672

M3 - Article

VL - 638

SP - 725

EP - 738

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 2 I

ER -