Weak homology of elliptical galaxies

By G. Bertin, Luca Ciotti, M. S. N. Superiore, Pisa Universita' degli Studi di Milano Osservatorio Ast dell'Aquila. 2002

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Studies of the Fundamental Plane of early{type galaxies, from small to intermediate redshifts, are generally carried out under the guiding principle that the Fundamental Plane reflects the existence of an underlying mass{luminosity relation for such galaxies, in a scenario where galaxies are homologous systems in dynamical equilibrium. In this paper we re-examine the question of whether a systematic non{homology could be partly responsible for the correlations that dene the Fundamental Plane. We start by studying a small set of objects characterized by photometric proles that have been pointed out to deviate signicantly from the standard R 1=4 law. For these objects we conrm that a generic R 1=n law, with n a free parameter, can provide superior ts (the best-t value of n can be lower than 2.5 or higher than 10), better than those that can be obtained by a pure R 1=4 law, by an R 1=4 + exponential model, and by other dynamically justied self{consistent models. Therefore, strictly speaking, elliptical galaxies should not be considered homologous dynamical systems. Still, a case for weak homology, useful for the interpretation of the Fundamental Plane, could be made if the best-t parameter n, as often reported, correlates with galaxy luminosity L, provided the underlying dynamical structure also follows a systematic trend with luminosity. We demonstrate that this statement may be true even in the presence of signicant scatter in the correlation n(L). Preliminary indications provided by a set of \data points" associated with a sample of 14 galaxies suggest that neither the strict homology nor the constant stellar mass{ to{light solution are a satisfactory explanation of the observed Fundamental Plane. These conclusions await further extensions and clarications, because the class of low{luminosity early{type galaxies, which contribute signicantly to the Fundamental Plane, falls outside the simple dynamical framework considered here and because dynamical considerations should be supplemented with other important constraints derived from the evolution of stellar populations.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/00404d21a85b99c95f166dc1accad9207a161d51

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Citations in the corpus

STELLAR KINEMATICS OF z ∼ 2 GALAXIES AND THE INSIDE-OUT GROWTH OF QUIESCENT GALAXIES, (2012, methodology): “(2) This is computed from theoretical predictions forβ from spherical isotropic models described by the Sérsic profile, for different values ofn, and integrated to onere (cf. Bertin et al. 2002).”
The ATLAS3D project XV: benchmark for early-type galaxies scaling relations from 260 dynamical models: mass-to-light ratio, dark matter, fundamental plane and mass plane (2012, methodology): “In the bottom-left panel, we change the virial coefficient β(n) according the predictions of spherical isotropic models with a Sérsic profile (e.g. Prugniel & Simien 1997; Bertin et al. 2002).”
WHAT TURNS GALAXIES OFF? THE DIFFERENT MORPHOLOGIES OF STAR-FORMING AND QUIESCENT GALAXIES SINCE z ∼ 2 FROM CANDELS (2011, methodology): “…and Sérsic index, where:σ′2 = GM∗ Kν (n)re √ (b/a) , and Kν (n) = 0.954+ 73.3210.465+(n−0.94)2 scalesM/re in a physically-motivated way to account for the structure of a galaxy via the Sérsic index (Bertin et al. 2002, amounting to velocity dispersion at a fixedM/re that are∼ 0.1 dex lower forn .”
Galaxy merging, the fundamental plane of elliptical galaxies and the MBH-σ0 relation (2003, result): “We note that higher values of the best fit parameter m correspond to more massive systems, a trend similar to that observed in Es§ (see, e.g., Caon, Capaccioli & D’Onofrio 1993, Prugniel & Simien 1997, Bertin et al. 2002).”
SUPERDENSE GALAXIES AND THE MASS–SIZE RELATION AT LOW REDSHIFT (2012, methodology): “We compute the dynamical mass of all early-type (ellipticals + S0s) galaxies in our mass-limited sample following the formulation by Bertin et al. (2002): Mdyn = (K(n)σ2Re)/G (5) where K(n) = [73.32/(10.465+ (n− 0.95)2)] + 0.954 (6) using the GASPHOT Sersic indexn and circularized radius Re and the…”
Structure and Kinematics of Early-Type Galaxies from Integral Field Spectroscopy (2016, background): “The amount of σ variation is again in principle sufficient to explain a major part of the FP tilt (Ciotti et al. 1996; Graham & Colless 1997; Prugniel & Simien 1997; Bertin et al. 2002; Trujillo et al. 2004a).”
The Evolution and Structure of Early-Type Field Galaxies: A Combined Statistical Analysis of Gravitational Lenses (2004, background): “…the degree to which early-type galaxies form a homologous population remains a problem of great interest (e.g., Faber et al. 1987; Caon et al. 1993; Bertin et al. 1994, 2002; van Albada et al. 1995; Ciotti et al. 1996; Pahre et al. 1998a; Gerhard et al. 2001; Borriello et al. 2003; Trujillo et al.…”
Galaxy Masses: A Review (2013, methodology): “1992; Bertin et al. 1992; Loewenstein & White 1999; Keeton 2001; Padmanabhan et al. 2004). In addition to degeneracies, some methods also become problematic beyond the local universe considering the limited signal-to-noise ratio of observations with presentday telescopes. In this section, we focus o”