Architecture of the Andromeda galaxy: A quantitative analysis of clustering in the inner stellar halo

P. R. Kafle, S. Sharma, A. S G Robotham, G. F. Lewis, S. P. Driver

Research output: Contribution to journalArticle

2 Citations (Scopus)
171 Downloads (Pure)

Abstract

We present a quantitative measurement of the amount of clustering present in the inner~30 kpc of the stellar halo of the Andromeda galaxy (M31). For this we analyse the angular positions and radial velocities of the carefully selected planetary nebulae in the M31 stellar halo. We study the cumulative distribution of pairwise distances in angular position and line-of-sight velocity space, and find that the M31 stellar halo contains substantially more stars in the form of close pairs as compared to that of a featureless smooth halo. In comparison to a smoothed/scrambled distribution, we estimate that the clustering excess in the M31 inner halo is roughly 40 per cent at maximum and on average ~20 per cent. Importantly, comparing against the 11 stellar halo models of Bullock & Johnston, which were simulated within the context of the ΛCDM (Λ cold dark matter) cosmological paradigm, we find that the amount of substructures in the M31 stellar halo closely resembles that of a typical ΛCDM halo.

Original languageEnglish
Pages (from-to)4858-4865
Number of pages8
JournalMonthly Notices of the Royal Astronomical Society
Volume464
Issue number4
DOIs
Publication statusPublished - 1 Feb 2017

Fingerprint

Andromeda Galaxy
quantitative analysis
halos
dark matter
cold
distribution
planetary nebulae
substructures
radial velocity
line of sight
stars

Cite this

@article{41ebc8c43f2049ef88b93e601173bd2f,
title = "Architecture of the Andromeda galaxy: A quantitative analysis of clustering in the inner stellar halo",
abstract = "We present a quantitative measurement of the amount of clustering present in the inner~30 kpc of the stellar halo of the Andromeda galaxy (M31). For this we analyse the angular positions and radial velocities of the carefully selected planetary nebulae in the M31 stellar halo. We study the cumulative distribution of pairwise distances in angular position and line-of-sight velocity space, and find that the M31 stellar halo contains substantially more stars in the form of close pairs as compared to that of a featureless smooth halo. In comparison to a smoothed/scrambled distribution, we estimate that the clustering excess in the M31 inner halo is roughly 40 per cent at maximum and on average ~20 per cent. Importantly, comparing against the 11 stellar halo models of Bullock & Johnston, which were simulated within the context of the ΛCDM (Λ cold dark matter) cosmological paradigm, we find that the amount of substructures in the M31 stellar halo closely resembles that of a typical ΛCDM halo.",
keywords = "Galaxies: individual: M31, Methods: statistical, Stars: individual: planetary nebulae",
author = "Kafle, {P. R.} and S. Sharma and Robotham, {A. S G} and Lewis, {G. F.} and Driver, {S. P.}",
year = "2017",
month = "2",
day = "1",
doi = "10.1093/mnras/stw2732",
language = "English",
volume = "464",
pages = "4858--4865",
journal = "Monthly Notices of the Royal Astronomical Society",
issn = "0035-8711",
publisher = "OXFORD UNIV PRESS UNITED KINGDOM",
number = "4",

}

TY - JOUR

T1 - Architecture of the Andromeda galaxy

T2 - A quantitative analysis of clustering in the inner stellar halo

AU - Kafle, P. R.

AU - Sharma, S.

AU - Robotham, A. S G

AU - Lewis, G. F.

AU - Driver, S. P.

PY - 2017/2/1

Y1 - 2017/2/1

N2 - We present a quantitative measurement of the amount of clustering present in the inner~30 kpc of the stellar halo of the Andromeda galaxy (M31). For this we analyse the angular positions and radial velocities of the carefully selected planetary nebulae in the M31 stellar halo. We study the cumulative distribution of pairwise distances in angular position and line-of-sight velocity space, and find that the M31 stellar halo contains substantially more stars in the form of close pairs as compared to that of a featureless smooth halo. In comparison to a smoothed/scrambled distribution, we estimate that the clustering excess in the M31 inner halo is roughly 40 per cent at maximum and on average ~20 per cent. Importantly, comparing against the 11 stellar halo models of Bullock & Johnston, which were simulated within the context of the ΛCDM (Λ cold dark matter) cosmological paradigm, we find that the amount of substructures in the M31 stellar halo closely resembles that of a typical ΛCDM halo.

AB - We present a quantitative measurement of the amount of clustering present in the inner~30 kpc of the stellar halo of the Andromeda galaxy (M31). For this we analyse the angular positions and radial velocities of the carefully selected planetary nebulae in the M31 stellar halo. We study the cumulative distribution of pairwise distances in angular position and line-of-sight velocity space, and find that the M31 stellar halo contains substantially more stars in the form of close pairs as compared to that of a featureless smooth halo. In comparison to a smoothed/scrambled distribution, we estimate that the clustering excess in the M31 inner halo is roughly 40 per cent at maximum and on average ~20 per cent. Importantly, comparing against the 11 stellar halo models of Bullock & Johnston, which were simulated within the context of the ΛCDM (Λ cold dark matter) cosmological paradigm, we find that the amount of substructures in the M31 stellar halo closely resembles that of a typical ΛCDM halo.

KW - Galaxies: individual: M31

KW - Methods: statistical

KW - Stars: individual: planetary nebulae

UR - http://www.scopus.com/inward/record.url?scp=85014821159&partnerID=8YFLogxK

U2 - 10.1093/mnras/stw2732

DO - 10.1093/mnras/stw2732

M3 - Article

VL - 464

SP - 4858

EP - 4865

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 4

ER -