The University of Southampton
University of Southampton Institutional Repository

Selection bias in dynamically-measured super-massive black hole samples: its consequences and the quest for the most fundamental relation

Selection bias in dynamically-measured super-massive black hole samples: its consequences and the quest for the most fundamental relation
Selection bias in dynamically-measured super-massive black hole samples: its consequences and the quest for the most fundamental relation
We compare the set of local galaxies having dynamically measured black holes with a large, unbiased sample of galaxies extracted from the Sloan Digital Sky Survey. We confirm earlier work showing that the majority of black hole hosts have significantly higher velocity dispersions ? than local galaxies of similar stellar mass. We use Monte Carlo simulations to illustrate the effect on black hole scaling relations if this bias arises from the requirement that the black hole sphere of influence must be resolved to measure black hole masses with spatially resolved kinematics. We find that this selection effect artificially increases the normalization of the Mbh–? relation by a factor of at least ?3; the bias for the Mbh–Mstar relation is even larger. Our Monte Carlo simulations and analysis of the residuals from scaling relations both indicate that ? is more fundamental than Mstar or effective radius. In particular, the Mbh–Mstar relation is mostly a consequence of the Mbh–? and ?–Mstar relations, and is heavily biased by up to a factor of 50 at small masses. This helps resolve the discrepancy between dynamically based black hole–galaxy scaling relations versus those of active galaxies. Our simulations also disfavour broad distributions of black hole masses at fixed ?. Correcting for this bias suggests that the calibration factor used to estimate black hole masses in active galaxies should be reduced to values of fvir ? 1. Black hole mass densities should also be proportionally smaller, perhaps implying significantly higher radiative efficiencies/black hole spins. Reducing black hole masses also reduces the gravitational wave signal expected from black hole mergers.
0035-8711
3119-3142
Shankar, Francesco
b10c91e4-85cd-4394-a18a-d4f049fd9cdb
Bernardi, Mariangela
51f0929c-ba65-4d9c-a814-673442f48d75
Sheth, Ravi K.
94b203a4-bea4-461b-a237-14d548264e15
Ferrarese, Laura
6ebe2439-3ac8-4b86-a403-5506a9bb23f5
Graham, Alister W.
0d879822-c286-4901-9ea3-57204a4fcde9
Savorgnan, Giulia
c06d64d6-1875-44e0-885f-d4dc1363afe4
Allevato, Viola
cced4e40-6a45-4261-911a-442d99a6aeb7
Marconi, Alessandro
e2ece26f-5d52-4077-a843-5da9b3768ccc
Lasker, Ronald
e57bfda6-c14f-4929-a531-f30221abaefa
Lapi, Andrea
126b5f87-60fa-4a57-8b84-802d5ffb1f17
Shankar, Francesco
b10c91e4-85cd-4394-a18a-d4f049fd9cdb
Bernardi, Mariangela
51f0929c-ba65-4d9c-a814-673442f48d75
Sheth, Ravi K.
94b203a4-bea4-461b-a237-14d548264e15
Ferrarese, Laura
6ebe2439-3ac8-4b86-a403-5506a9bb23f5
Graham, Alister W.
0d879822-c286-4901-9ea3-57204a4fcde9
Savorgnan, Giulia
c06d64d6-1875-44e0-885f-d4dc1363afe4
Allevato, Viola
cced4e40-6a45-4261-911a-442d99a6aeb7
Marconi, Alessandro
e2ece26f-5d52-4077-a843-5da9b3768ccc
Lasker, Ronald
e57bfda6-c14f-4929-a531-f30221abaefa
Lapi, Andrea
126b5f87-60fa-4a57-8b84-802d5ffb1f17

Shankar, Francesco, Bernardi, Mariangela, Sheth, Ravi K., Ferrarese, Laura, Graham, Alister W., Savorgnan, Giulia, Allevato, Viola, Marconi, Alessandro, Lasker, Ronald and Lapi, Andrea (2016) Selection bias in dynamically-measured super-massive black hole samples: its consequences and the quest for the most fundamental relation. Monthly Notices of the Royal Astronomical Society, 460 (3), 3119-3142. (doi:10.1093/mnras/stw678).

Record type: Article

Abstract

We compare the set of local galaxies having dynamically measured black holes with a large, unbiased sample of galaxies extracted from the Sloan Digital Sky Survey. We confirm earlier work showing that the majority of black hole hosts have significantly higher velocity dispersions ? than local galaxies of similar stellar mass. We use Monte Carlo simulations to illustrate the effect on black hole scaling relations if this bias arises from the requirement that the black hole sphere of influence must be resolved to measure black hole masses with spatially resolved kinematics. We find that this selection effect artificially increases the normalization of the Mbh–? relation by a factor of at least ?3; the bias for the Mbh–Mstar relation is even larger. Our Monte Carlo simulations and analysis of the residuals from scaling relations both indicate that ? is more fundamental than Mstar or effective radius. In particular, the Mbh–Mstar relation is mostly a consequence of the Mbh–? and ?–Mstar relations, and is heavily biased by up to a factor of 50 at small masses. This helps resolve the discrepancy between dynamically based black hole–galaxy scaling relations versus those of active galaxies. Our simulations also disfavour broad distributions of black hole masses at fixed ?. Correcting for this bias suggests that the calibration factor used to estimate black hole masses in active galaxies should be reduced to values of fvir ? 1. Black hole mass densities should also be proportionally smaller, perhaps implying significantly higher radiative efficiencies/black hole spins. Reducing black hole masses also reduces the gravitational wave signal expected from black hole mergers.

Text
__soton.ac.uk_ude_PersonalFiles_Users_fs1y12_mydocuments_1603.01276v1.pdf - Accepted Manuscript
Restricted to Repository staff only
Request a copy
Text
__userfiles.soton.ac.uk_Users_nl2_mydesktop_Deposits_One off_1603 01276.pdf - Accepted Manuscript
Download (2MB)

More information

Accepted/In Press date: 18 March 2016
e-pub ahead of print date: 23 March 2016
Published date: 11 August 2016
Additional Information: Arxiv copy 1603.01276 Author Shankar confirms AM copy.
Organisations: Astronomy Group

Identifiers

Local EPrints ID: 397017
URI: http://eprints.soton.ac.uk/id/eprint/397017
ISSN: 0035-8711
PURE UUID: 71fc52f4-7a0e-487d-950e-1e5bb79896e8

Catalogue record

Date deposited: 27 Jun 2016 09:19
Last modified: 16 Dec 2019 19:51

Export record

Altmetrics

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×