Title: The stellar mass Fundamental Plane: the virial relation and a very thin plane for slow rotators

Abstract

ABSTRACT Early-type galaxies – slow and fast rotating ellipticals (E-SRs and E-FRs) and S0s/lenticulars – define a Fundamental Plane (FP) in the space of half-light radius Re, enclosed surface brightness Ie, and velocity dispersion σe. Since Ie and σe are distance-independent measurements, the thickness of the FP is often expressed in terms of the accuracy with which Ie and σe can be used to estimate sizes Re. We show that: (1) The thickness of the FP depends strongly on morphology. If the sample only includes E-SRs, then the observed scatter in Re is $$\sim 16{{\ \rm per\ cent}}$$, of which only $$\sim 9{{\ \rm per\ cent}}$$ is intrinsic. Removing galaxies with M* < 1011 M⊙ further reduces the observed scatter to $$\sim 13{{\ \rm per\ cent}}$$ ($$\sim 4{{\ \rm per\ cent}}$$ intrinsic). The observed scatter increases to $$\sim 25{{\ \rm per\ cent}}$$ usually quoted in the literature if E-FRs and S0s are added. If the FP is defined using the eigenvectors of the covariance matrix of the observables, then the E-SRs again define an exceptionally thin FP, with intrinsic scatter of only 5 per cent orthogonal to the plane. (2) The structure within the FP is most easily understood as arising from the fact that Ie and σe are nearly independent, whereas the Re−Ie and Re−σe correlations are nearly equal and opposite. (3) If the coefficients of the FP differ from those associated with the virial theorem the plane is said to be ‘tilted’. If we multiply Ie by the global stellar mass-to-light ratio M*/L and we account for non-homology across the population by using Sérsic photometry, then the resulting stellar mass FP is less tilted. Accounting self-consistently for M*/L gradients will change the tilt. The tilt we currently see suggests that the efficiency of turning baryons into stars increases and/or the dark matter fraction decreases as stellar surface brightness increases.

Authors:

Bernardi, M. ^[1]; Domínguez Sánchez, H. ^[2]; Margalef-Bentabol, B. ^[1]; Nikakhtar, F. ^[1]; Sheth, R. K. ^[1]

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+ Show Author Affiliations

1. Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA
2. Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA, Institute of Space Sciences (ICE, CSIC), Campus UAB, Carrer de Magrans, E-08193 Barcelona, Spain

Publication Date:

Tue May 05 00:00:00 EDT 2020

Sponsoring Org.:

USDOE

OSTI Identifier:

1617723

Resource Type:

Published Article

Journal Name:

Monthly Notices of the Royal Astronomical Society

Additional Journal Information:

Journal Name: Monthly Notices of the Royal Astronomical Society Journal Volume: 494 Journal Issue: 4; Journal ID: ISSN 0035-8711

Publisher:

Oxford University Press

Country of Publication:

United Kingdom

Language:

English