Universal IMF versus dark halo response in early-type galaxies

Breaking the degeneracy with the Fundamental Plane

Aaron A. Dutton, Andrea Maccio, J. Trevor Mendel, Luc Simard

Research output: Contribution to journalArticle

Abstract

We use the relations between aperture stellar velocity dispersion (σap), stellar mass (MSPS) and galaxy size (Re) for a sample of ~150 000 early-type galaxies from Sloan Digital Sky Survey/DR7 to place constraints on the stellar initial mass function (IMF) and dark halo response to galaxy formation.We build λ cold dark matter-based mass models that reproduce, by construction, the relations between galaxy size, light concentration and stellar mass, and use the spherical Jeans equations to predict σap. Given our model assumptions (including those in the stellar population synthesis models), we find that reproducing the median σap versus MSPS relation is not possible with both a universal IMF and a universal dark halo response. Significant departures from a universal IMF and/or dark halo response are required, but there is a degeneracy between these two solutions. We show that this degeneracy can be broken using the strength of the correlation between residuals of the velocity-mass (δlog σap) and size-mass (δlog Re) relations. The slope of this correlation, ∂VR = δlog σap/δ logRe, varies systematically with galaxy mass from ∂VR ≃ -0.45 at MSPS ~ 1010M⊙ to ∂VR ≃ -0.15 at MSPS ~ 1011.6M⊙. The virial Fundamental Plane (FP) has ∂VR = -1/2, and thus we find that the tilt of the observed FP is mass dependent. Reproducing this tilt requires both a nonuniversal IMF and a non-universal halo response. Our best model has mass-follows-light at low masses (MSPS ≲ 1011.2M⊙) and unmodified Navarro, Frenk and White haloes at MSPS ~ 1011.5M⊙. The stellar masses imply a mass-dependent IMF which is 'lighter' than Salpeter at low masses and 'heavier' than Salpeter at high masses.

Original languageEnglish (US)
Pages (from-to)2496-2511
Number of pages16
JournalMonthly Notices of the Royal Astronomical Society
Volume432
Issue number3
DOIs
StatePublished - Jun 1 2013

Fingerprint

halos
galaxies
virtual reality
stellar mass
tilt
galactic evolution
dark matter
apertures
slopes

Keywords

  • Dark matter
  • Galaxies: elliptical and lenticular, cD
  • Galaxies: fundamental parameters
  • Galaxies: haloes
  • Galaxies: kinematics and dynamics
  • Stars: luminosity function, mass function

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Universal IMF versus dark halo response in early-type galaxies : Breaking the degeneracy with the Fundamental Plane. / Dutton, Aaron A.; Maccio, Andrea; Mendel, J. Trevor; Simard, Luc.

In: Monthly Notices of the Royal Astronomical Society, Vol. 432, No. 3, 01.06.2013, p. 2496-2511.

Research output: Contribution to journalArticle

@article{28b097e45fbb4b359740df7382c240cb,
title = "Universal IMF versus dark halo response in early-type galaxies: Breaking the degeneracy with the Fundamental Plane",
abstract = "We use the relations between aperture stellar velocity dispersion (σap), stellar mass (MSPS) and galaxy size (Re) for a sample of ~150 000 early-type galaxies from Sloan Digital Sky Survey/DR7 to place constraints on the stellar initial mass function (IMF) and dark halo response to galaxy formation.We build λ cold dark matter-based mass models that reproduce, by construction, the relations between galaxy size, light concentration and stellar mass, and use the spherical Jeans equations to predict σap. Given our model assumptions (including those in the stellar population synthesis models), we find that reproducing the median σap versus MSPS relation is not possible with both a universal IMF and a universal dark halo response. Significant departures from a universal IMF and/or dark halo response are required, but there is a degeneracy between these two solutions. We show that this degeneracy can be broken using the strength of the correlation between residuals of the velocity-mass (δlog σap) and size-mass (δlog Re) relations. The slope of this correlation, ∂VR = δlog σap/δ logRe, varies systematically with galaxy mass from ∂VR ≃ -0.45 at MSPS ~ 1010M⊙ to ∂VR ≃ -0.15 at MSPS ~ 1011.6M⊙. The virial Fundamental Plane (FP) has ∂VR = -1/2, and thus we find that the tilt of the observed FP is mass dependent. Reproducing this tilt requires both a nonuniversal IMF and a non-universal halo response. Our best model has mass-follows-light at low masses (MSPS ≲ 1011.2M⊙) and unmodified Navarro, Frenk and White haloes at MSPS ~ 1011.5M⊙. The stellar masses imply a mass-dependent IMF which is 'lighter' than Salpeter at low masses and 'heavier' than Salpeter at high masses.",
keywords = "Dark matter, Galaxies: elliptical and lenticular, cD, Galaxies: fundamental parameters, Galaxies: haloes, Galaxies: kinematics and dynamics, Stars: luminosity function, mass function",
author = "Dutton, {Aaron A.} and Andrea Maccio and Mendel, {J. Trevor} and Luc Simard",
year = "2013",
month = "6",
day = "1",
doi = "10.1093/mnras/stt608",
language = "English (US)",
volume = "432",
pages = "2496--2511",
journal = "Monthly Notices of the Royal Astronomical Society",
issn = "0035-8711",
publisher = "Oxford University Press",
number = "3",

}

TY - JOUR

T1 - Universal IMF versus dark halo response in early-type galaxies

T2 - Breaking the degeneracy with the Fundamental Plane

AU - Dutton, Aaron A.

AU - Maccio, Andrea

AU - Mendel, J. Trevor

AU - Simard, Luc

PY - 2013/6/1

Y1 - 2013/6/1

N2 - We use the relations between aperture stellar velocity dispersion (σap), stellar mass (MSPS) and galaxy size (Re) for a sample of ~150 000 early-type galaxies from Sloan Digital Sky Survey/DR7 to place constraints on the stellar initial mass function (IMF) and dark halo response to galaxy formation.We build λ cold dark matter-based mass models that reproduce, by construction, the relations between galaxy size, light concentration and stellar mass, and use the spherical Jeans equations to predict σap. Given our model assumptions (including those in the stellar population synthesis models), we find that reproducing the median σap versus MSPS relation is not possible with both a universal IMF and a universal dark halo response. Significant departures from a universal IMF and/or dark halo response are required, but there is a degeneracy between these two solutions. We show that this degeneracy can be broken using the strength of the correlation between residuals of the velocity-mass (δlog σap) and size-mass (δlog Re) relations. The slope of this correlation, ∂VR = δlog σap/δ logRe, varies systematically with galaxy mass from ∂VR ≃ -0.45 at MSPS ~ 1010M⊙ to ∂VR ≃ -0.15 at MSPS ~ 1011.6M⊙. The virial Fundamental Plane (FP) has ∂VR = -1/2, and thus we find that the tilt of the observed FP is mass dependent. Reproducing this tilt requires both a nonuniversal IMF and a non-universal halo response. Our best model has mass-follows-light at low masses (MSPS ≲ 1011.2M⊙) and unmodified Navarro, Frenk and White haloes at MSPS ~ 1011.5M⊙. The stellar masses imply a mass-dependent IMF which is 'lighter' than Salpeter at low masses and 'heavier' than Salpeter at high masses.

AB - We use the relations between aperture stellar velocity dispersion (σap), stellar mass (MSPS) and galaxy size (Re) for a sample of ~150 000 early-type galaxies from Sloan Digital Sky Survey/DR7 to place constraints on the stellar initial mass function (IMF) and dark halo response to galaxy formation.We build λ cold dark matter-based mass models that reproduce, by construction, the relations between galaxy size, light concentration and stellar mass, and use the spherical Jeans equations to predict σap. Given our model assumptions (including those in the stellar population synthesis models), we find that reproducing the median σap versus MSPS relation is not possible with both a universal IMF and a universal dark halo response. Significant departures from a universal IMF and/or dark halo response are required, but there is a degeneracy between these two solutions. We show that this degeneracy can be broken using the strength of the correlation between residuals of the velocity-mass (δlog σap) and size-mass (δlog Re) relations. The slope of this correlation, ∂VR = δlog σap/δ logRe, varies systematically with galaxy mass from ∂VR ≃ -0.45 at MSPS ~ 1010M⊙ to ∂VR ≃ -0.15 at MSPS ~ 1011.6M⊙. The virial Fundamental Plane (FP) has ∂VR = -1/2, and thus we find that the tilt of the observed FP is mass dependent. Reproducing this tilt requires both a nonuniversal IMF and a non-universal halo response. Our best model has mass-follows-light at low masses (MSPS ≲ 1011.2M⊙) and unmodified Navarro, Frenk and White haloes at MSPS ~ 1011.5M⊙. The stellar masses imply a mass-dependent IMF which is 'lighter' than Salpeter at low masses and 'heavier' than Salpeter at high masses.

KW - Dark matter

KW - Galaxies: elliptical and lenticular, cD

KW - Galaxies: fundamental parameters

KW - Galaxies: haloes

KW - Galaxies: kinematics and dynamics

KW - Stars: luminosity function, mass function

UR - http://www.scopus.com/inward/record.url?scp=84879590588&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84879590588&partnerID=8YFLogxK

U2 - 10.1093/mnras/stt608

DO - 10.1093/mnras/stt608

M3 - Article

VL - 432

SP - 2496

EP - 2511

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 3

ER -