Orbits of massive satellite galaxies - II. Bayesian estimates of the Milky Way and Andromeda masses using high-precision astrometry and cosmological simulations
In the era of high-precision astrometry, space observatories like the Hubble Space Telescope (HST) and Gaia are providing unprecedented 6D phase-space information of satellite galaxies. Such measurements can shed light on the structure and assembly history of the Local Group, but improved statistica...
Main Authors: | , , |
---|---|
Other Authors: | |
Language: | en |
Published: |
OXFORD UNIV PRESS
2017
|
Subjects: | |
Online Access: | http://hdl.handle.net/10150/624428 http://arizona.openrepository.com/arizona/handle/10150/624428 |
id |
ndltd-arizona.edu-oai-arizona.openrepository.com-10150-624428 |
---|---|
record_format |
oai_dc |
spelling |
ndltd-arizona.edu-oai-arizona.openrepository.com-10150-6244282017-06-29T03:00:33Z Orbits of massive satellite galaxies - II. Bayesian estimates of the Milky Way and Andromeda masses using high-precision astrometry and cosmological simulations Patel, Ekta Besla, Gurtina Mandel, Kaisey Univ Arizona, Dept Astron Galaxy: fundamental parameters galaxies: evolution galaxies: kinematics and dynamics Local Group In the era of high-precision astrometry, space observatories like the Hubble Space Telescope (HST) and Gaia are providing unprecedented 6D phase-space information of satellite galaxies. Such measurements can shed light on the structure and assembly history of the Local Group, but improved statistical methods are needed to use them efficiently. Here we illustrate such a method using analogues of the Local Group's two most massive satellite galaxies, the Large Magellanic Cloud (LMC) and Triangulum (M33), from the Illustris dark-matter-only cosmological simulation. We use a Bayesian inference scheme combining measurements of positions, velocities and specific orbital angular momenta (j) of the LMC/M33 with importance sampling of their simulated analogues to compute posterior estimates of the Milky Way (MW) and Andromeda's (M31) halo masses. We conclude that the resulting host halo mass is more susceptible to bias when using measurements of the current position and velocity of satellites, especially when satellites are at short-lived phases of their orbits (i.e. at pericentre). Instead, the j value of a satellite is well conserved over time and provides a more reliable constraint on host mass. The inferred virial mass of the MW(M31) using j of the LMC (M33) is M-vir,M- MW = 1.02(-0.55)(+0.77) x 10(12) M-circle dot (M-vir,M- M31 = 1.37(-0.75)(+1.39) x 10(12) M-circle dot). Choosing simulated analogues whose j values are consistent with the conventional picture of a previous (<3 Gyr ago), close encounter (<100 kpc) of M33 about M31 results in a very low virial mass for M31 (similar to 10(12) M-circle dot). This supports the new scenario put forth in Patel, Besla & Sohn, wherein M33 is on its first passage about M31 or on a long-period orbit. We conclude that this Bayesian inference scheme, utilizing satellite j, is a promising method to reduce the current factor of 2 spread in the mass range of the MW and M31. This method is easily adaptable to include additional satellites as new 6D phase-space information becomes available from HST, Gaia and the James Webb Space Telescope. 2017-07 Article Orbits of massive satellite galaxies - II. Bayesian estimates of the Milky Way and Andromeda masses using high-precision astrometry and cosmological simulations 2017, 468 (3):3428 Monthly Notices of the Royal Astronomical Society 0035-8711 1365-2966 10.1093/mnras/stx698 http://hdl.handle.net/10150/624428 http://arizona.openrepository.com/arizona/handle/10150/624428 Monthly Notices of the Royal Astronomical Society en https://academic.oup.com/mnras/article-lookup/doi/10.1093/mnras/stx698 © 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society OXFORD UNIV PRESS |
collection |
NDLTD |
language |
en |
sources |
NDLTD |
topic |
Galaxy: fundamental parameters galaxies: evolution galaxies: kinematics and dynamics Local Group |
spellingShingle |
Galaxy: fundamental parameters galaxies: evolution galaxies: kinematics and dynamics Local Group Patel, Ekta Besla, Gurtina Mandel, Kaisey Orbits of massive satellite galaxies - II. Bayesian estimates of the Milky Way and Andromeda masses using high-precision astrometry and cosmological simulations |
description |
In the era of high-precision astrometry, space observatories like the Hubble Space Telescope (HST) and Gaia are providing unprecedented 6D phase-space information of satellite galaxies. Such measurements can shed light on the structure and assembly history of the Local Group, but improved statistical methods are needed to use them efficiently. Here we illustrate such a method using analogues of the Local Group's two most massive satellite galaxies, the Large Magellanic Cloud (LMC) and Triangulum (M33), from the Illustris dark-matter-only cosmological simulation. We use a Bayesian inference scheme combining measurements of positions, velocities and specific orbital angular momenta (j) of the LMC/M33 with importance sampling of their simulated analogues to compute posterior estimates of the Milky Way (MW) and Andromeda's (M31) halo masses. We conclude that the resulting host halo mass is more susceptible to bias when using measurements of the current position and velocity of satellites, especially when satellites are at short-lived phases of their orbits (i.e. at pericentre). Instead, the j value of a satellite is well conserved over time and provides a more reliable constraint on host mass. The inferred virial mass of the MW(M31) using j of the LMC (M33) is M-vir,M- MW = 1.02(-0.55)(+0.77) x 10(12) M-circle dot (M-vir,M- M31 = 1.37(-0.75)(+1.39) x 10(12) M-circle dot). Choosing simulated analogues whose j values are consistent with the conventional picture of a previous (<3 Gyr ago), close encounter (<100 kpc) of M33 about M31 results in a very low virial mass for M31 (similar to 10(12) M-circle dot). This supports the new scenario put forth in Patel, Besla & Sohn, wherein M33 is on its first passage about M31 or on a long-period orbit. We conclude that this Bayesian inference scheme, utilizing satellite j, is a promising method to reduce the current factor of 2 spread in the mass range of the MW and M31. This method is easily adaptable to include additional satellites as new 6D phase-space information becomes available from HST, Gaia and the James Webb Space Telescope. |
author2 |
Univ Arizona, Dept Astron |
author_facet |
Univ Arizona, Dept Astron Patel, Ekta Besla, Gurtina Mandel, Kaisey |
author |
Patel, Ekta Besla, Gurtina Mandel, Kaisey |
author_sort |
Patel, Ekta |
title |
Orbits of massive satellite galaxies - II. Bayesian estimates of the Milky Way and Andromeda masses using high-precision astrometry and cosmological simulations |
title_short |
Orbits of massive satellite galaxies - II. Bayesian estimates of the Milky Way and Andromeda masses using high-precision astrometry and cosmological simulations |
title_full |
Orbits of massive satellite galaxies - II. Bayesian estimates of the Milky Way and Andromeda masses using high-precision astrometry and cosmological simulations |
title_fullStr |
Orbits of massive satellite galaxies - II. Bayesian estimates of the Milky Way and Andromeda masses using high-precision astrometry and cosmological simulations |
title_full_unstemmed |
Orbits of massive satellite galaxies - II. Bayesian estimates of the Milky Way and Andromeda masses using high-precision astrometry and cosmological simulations |
title_sort |
orbits of massive satellite galaxies - ii. bayesian estimates of the milky way and andromeda masses using high-precision astrometry and cosmological simulations |
publisher |
OXFORD UNIV PRESS |
publishDate |
2017 |
url |
http://hdl.handle.net/10150/624428 http://arizona.openrepository.com/arizona/handle/10150/624428 |
work_keys_str_mv |
AT patelekta orbitsofmassivesatellitegalaxiesiibayesianestimatesofthemilkywayandandromedamassesusinghighprecisionastrometryandcosmologicalsimulations AT beslagurtina orbitsofmassivesatellitegalaxiesiibayesianestimatesofthemilkywayandandromedamassesusinghighprecisionastrometryandcosmologicalsimulations AT mandelkaisey orbitsofmassivesatellitegalaxiesiibayesianestimatesofthemilkywayandandromedamassesusinghighprecisionastrometryandcosmologicalsimulations |
_version_ |
1718478542628454400 |