OBSERVATIONAL EVIDENCE FOR A DARK SIDE TO NGC 5128'S GLOBULAR CLUSTER SYSTEM

Matthew A. Taylor, Thomas H. Puzia, Matias Gomez, Kristin A. Woodley

Resultado de la investigación: Article

19 Citas (Scopus)

Resumen

We present a study of the dynamical properties of 125 compact stellar systems (CSSs) in the nearby giant elliptical galaxy NGC 5128, using high-resolution spectra (R ≈ 26, 000) obtained with Very Large Telescope/FLAMES. Our results provide evidence for a new type of star cluster, based on the CSS dynamical mass scaling relations. All radial velocity (vr) and line-of-sight velocity dispersion (σlos) measurements are performed with the penalized pixel fitting (ppxf ) technique, which provided σppxf estimates for 115 targets. The σppxf estimates are corrected to the 2D projected half-light radii, σ1/2, as well as the cluster cores, σ0, accounting for observational/aperture effects and are combined with structural parameters, from high spatial resolution imaging, in order to derive total dynamical masses (Mdyn) for 112 members of NGC 5128's star cluster system. In total, 89 CSSs have dynamical masses measured for the first time along with the corresponding dynamical mass-to-light ratios (ΥVdyn). We find two distinct sequences in the ΥVdyn-Mdyn plane, which are well approximated by power laws of the forms ΥVdyn ∝ Mdyn0.33±0.04 and ΥVdyn ∝ Mdyn0.79±0.04. The shallower sequence corresponds to the very bright tail of the globular cluster luminosity function (GCLF), while the steeper relation appears to be populated by a distinct group of objects that require significant dark gravitating components such as central massive black holes and/or exotically concentrated dark matter distributions. This result would suggest that the formation and evolution of these CSSs are markedly different from the "classical" globular clusters in NGC 5128 and the Local Group, despite the fact that these clusters have luminosities similar to the GCLF turnover magnitude. We include a thorough discussion of myriad factors potentially influencing our measurements.

Idioma originalEnglish
Número de artículo65
PublicaciónAstrophysical Journal
Volumen805
N.º1
DOI
EstadoPublished - 20 may 2015

Huella dactilar

stellar systems
globular clusters
pixel
pixels
luminosity
star clusters
mass to light ratios
high resolution
elliptical galaxies
estimates
radial velocity
line of sight
dark matter
turnover
power law
spatial resolution
apertures
telescopes
scaling
radii

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Citar esto

Taylor, Matthew A. ; Puzia, Thomas H. ; Gomez, Matias ; Woodley, Kristin A. / OBSERVATIONAL EVIDENCE FOR A DARK SIDE TO NGC 5128'S GLOBULAR CLUSTER SYSTEM. En: Astrophysical Journal. 2015 ; Vol. 805, N.º 1.
@article{e4b58418000d426d8cce4f5939fe464d,
title = "OBSERVATIONAL EVIDENCE FOR A DARK SIDE TO NGC 5128'S GLOBULAR CLUSTER SYSTEM",
abstract = "We present a study of the dynamical properties of 125 compact stellar systems (CSSs) in the nearby giant elliptical galaxy NGC 5128, using high-resolution spectra (R ≈ 26, 000) obtained with Very Large Telescope/FLAMES. Our results provide evidence for a new type of star cluster, based on the CSS dynamical mass scaling relations. All radial velocity (vr) and line-of-sight velocity dispersion (σlos) measurements are performed with the penalized pixel fitting (ppxf ) technique, which provided σppxf estimates for 115 targets. The σppxf estimates are corrected to the 2D projected half-light radii, σ1/2, as well as the cluster cores, σ0, accounting for observational/aperture effects and are combined with structural parameters, from high spatial resolution imaging, in order to derive total dynamical masses (Mdyn) for 112 members of NGC 5128's star cluster system. In total, 89 CSSs have dynamical masses measured for the first time along with the corresponding dynamical mass-to-light ratios (ΥVdyn). We find two distinct sequences in the ΥVdyn-Mdyn plane, which are well approximated by power laws of the forms ΥVdyn ∝ Mdyn0.33±0.04 and ΥVdyn ∝ Mdyn0.79±0.04. The shallower sequence corresponds to the very bright tail of the globular cluster luminosity function (GCLF), while the steeper relation appears to be populated by a distinct group of objects that require significant dark gravitating components such as central massive black holes and/or exotically concentrated dark matter distributions. This result would suggest that the formation and evolution of these CSSs are markedly different from the {"}classical{"} globular clusters in NGC 5128 and the Local Group, despite the fact that these clusters have luminosities similar to the GCLF turnover magnitude. We include a thorough discussion of myriad factors potentially influencing our measurements.",
keywords = "Galaxies: individual (NGC 5128), Galaxies: star clusters: general Supporting material: machine-readable tables",
author = "Taylor, {Matthew A.} and Puzia, {Thomas H.} and Matias Gomez and Woodley, {Kristin A.}",
year = "2015",
month = "5",
day = "20",
doi = "10.1088/0004-637X/805/1/65",
language = "English",
volume = "805",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "1",

}

OBSERVATIONAL EVIDENCE FOR A DARK SIDE TO NGC 5128'S GLOBULAR CLUSTER SYSTEM. / Taylor, Matthew A.; Puzia, Thomas H.; Gomez, Matias; Woodley, Kristin A.

En: Astrophysical Journal, Vol. 805, N.º 1, 65, 20.05.2015.

Resultado de la investigación: Article

TY - JOUR

T1 - OBSERVATIONAL EVIDENCE FOR A DARK SIDE TO NGC 5128'S GLOBULAR CLUSTER SYSTEM

AU - Taylor, Matthew A.

AU - Puzia, Thomas H.

AU - Gomez, Matias

AU - Woodley, Kristin A.

PY - 2015/5/20

Y1 - 2015/5/20

N2 - We present a study of the dynamical properties of 125 compact stellar systems (CSSs) in the nearby giant elliptical galaxy NGC 5128, using high-resolution spectra (R ≈ 26, 000) obtained with Very Large Telescope/FLAMES. Our results provide evidence for a new type of star cluster, based on the CSS dynamical mass scaling relations. All radial velocity (vr) and line-of-sight velocity dispersion (σlos) measurements are performed with the penalized pixel fitting (ppxf ) technique, which provided σppxf estimates for 115 targets. The σppxf estimates are corrected to the 2D projected half-light radii, σ1/2, as well as the cluster cores, σ0, accounting for observational/aperture effects and are combined with structural parameters, from high spatial resolution imaging, in order to derive total dynamical masses (Mdyn) for 112 members of NGC 5128's star cluster system. In total, 89 CSSs have dynamical masses measured for the first time along with the corresponding dynamical mass-to-light ratios (ΥVdyn). We find two distinct sequences in the ΥVdyn-Mdyn plane, which are well approximated by power laws of the forms ΥVdyn ∝ Mdyn0.33±0.04 and ΥVdyn ∝ Mdyn0.79±0.04. The shallower sequence corresponds to the very bright tail of the globular cluster luminosity function (GCLF), while the steeper relation appears to be populated by a distinct group of objects that require significant dark gravitating components such as central massive black holes and/or exotically concentrated dark matter distributions. This result would suggest that the formation and evolution of these CSSs are markedly different from the "classical" globular clusters in NGC 5128 and the Local Group, despite the fact that these clusters have luminosities similar to the GCLF turnover magnitude. We include a thorough discussion of myriad factors potentially influencing our measurements.

AB - We present a study of the dynamical properties of 125 compact stellar systems (CSSs) in the nearby giant elliptical galaxy NGC 5128, using high-resolution spectra (R ≈ 26, 000) obtained with Very Large Telescope/FLAMES. Our results provide evidence for a new type of star cluster, based on the CSS dynamical mass scaling relations. All radial velocity (vr) and line-of-sight velocity dispersion (σlos) measurements are performed with the penalized pixel fitting (ppxf ) technique, which provided σppxf estimates for 115 targets. The σppxf estimates are corrected to the 2D projected half-light radii, σ1/2, as well as the cluster cores, σ0, accounting for observational/aperture effects and are combined with structural parameters, from high spatial resolution imaging, in order to derive total dynamical masses (Mdyn) for 112 members of NGC 5128's star cluster system. In total, 89 CSSs have dynamical masses measured for the first time along with the corresponding dynamical mass-to-light ratios (ΥVdyn). We find two distinct sequences in the ΥVdyn-Mdyn plane, which are well approximated by power laws of the forms ΥVdyn ∝ Mdyn0.33±0.04 and ΥVdyn ∝ Mdyn0.79±0.04. The shallower sequence corresponds to the very bright tail of the globular cluster luminosity function (GCLF), while the steeper relation appears to be populated by a distinct group of objects that require significant dark gravitating components such as central massive black holes and/or exotically concentrated dark matter distributions. This result would suggest that the formation and evolution of these CSSs are markedly different from the "classical" globular clusters in NGC 5128 and the Local Group, despite the fact that these clusters have luminosities similar to the GCLF turnover magnitude. We include a thorough discussion of myriad factors potentially influencing our measurements.

KW - Galaxies: individual (NGC 5128)

KW - Galaxies: star clusters: general Supporting material: machine-readable tables

UR - http://www.scopus.com/inward/record.url?scp=84930204601&partnerID=8YFLogxK

U2 - 10.1088/0004-637X/805/1/65

DO - 10.1088/0004-637X/805/1/65

M3 - Article

AN - SCOPUS:84930204601

VL - 805

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 1

M1 - 65

ER -