Angular momentum evolution of bulge stars in disc galaxies in NIHAO

Liang Wang, Danail Obreschkow, Claudia Del P. Lagos, Sarah M. Sweet, Deanne Fisher, Karl Glazebrook, Andrea V. Macciò, Aaron A. Dutton, Xi Kang

Research output: Contribution to journalArticle

Abstract

We study the origin of bulge stars and their angular momentum (AM) evolution in 10 spiral galaxies with baryonic masses above 1010 M in the Numerical Investigation of a Hundred Astrophysical Objects galaxy formation simulations. The simulated galaxies are in good agreement with observations of the relation between the specific AM and mass of the baryonic component and the stellar bulge-to-total ratio (B/T). We divide the star particles at z = 0 into disc and bulge components using a hybrid photometric/kinematic decomposition method that identifies all the central mass above an exponential disc profile as the ‘bulge’. By tracking the bulge star particles back in time, we find that on average 95 per cent of the bulge stars formed in situ, 3 per cent formed ex situ in satellites of the same halo, and only 2 per cent formed ex situ in external galaxies. The evolution of the AM distribution of the bulge stars paints an interesting picture: The higher the final B/T, the more the specific AM remains preserved during the bulge formation. In all cases, bulge stars migrate significantly towards the central region, reducing their average galactocentric radius by roughly a factor 2, independently of the final B/T value. However, in the higher B/T ( 0.2) objects, the velocity of the bulge stars increases and the AM of the bulge is almost conserved, whereas at lower B/T values, the velocity of the bulge stars decreases and the AM of the bulge reduces. The correlation between the evolution of the AM and B/T suggests that bulge formation and disc formation are closely linked and cannot be treated as independent processes.

Original languageEnglish
Pages (from-to)5477-5491
Number of pages15
JournalMonthly Notices of the Royal Astronomical Society
Volume482
Issue number4
DOIs
Publication statusPublished - 1 Feb 2019

Fingerprint

disk galaxies
angular momentum
stars
galaxies
paints
galactic evolution
spiral galaxies
kinematics
halos
astrophysics
decomposition
radii
profiles
simulation
in situ

Cite this

Wang, Liang ; Obreschkow, Danail ; Lagos, Claudia Del P. ; Sweet, Sarah M. ; Fisher, Deanne ; Glazebrook, Karl ; Macciò, Andrea V. ; Dutton, Aaron A. ; Kang, Xi. / Angular momentum evolution of bulge stars in disc galaxies in NIHAO. In: Monthly Notices of the Royal Astronomical Society. 2019 ; Vol. 482, No. 4. pp. 5477-5491.
@article{bd58cf11c01449f98abcb7c9d2baa89e,
title = "Angular momentum evolution of bulge stars in disc galaxies in NIHAO",
abstract = "We study the origin of bulge stars and their angular momentum (AM) evolution in 10 spiral galaxies with baryonic masses above 1010 M in the Numerical Investigation of a Hundred Astrophysical Objects galaxy formation simulations. The simulated galaxies are in good agreement with observations of the relation between the specific AM and mass of the baryonic component and the stellar bulge-to-total ratio (B/T). We divide the star particles at z = 0 into disc and bulge components using a hybrid photometric/kinematic decomposition method that identifies all the central mass above an exponential disc profile as the ‘bulge’. By tracking the bulge star particles back in time, we find that on average 95 per cent of the bulge stars formed in situ, 3 per cent formed ex situ in satellites of the same halo, and only 2 per cent formed ex situ in external galaxies. The evolution of the AM distribution of the bulge stars paints an interesting picture: The higher the final B/T, the more the specific AM remains preserved during the bulge formation. In all cases, bulge stars migrate significantly towards the central region, reducing their average galactocentric radius by roughly a factor 2, independently of the final B/T value. However, in the higher B/T ( 0.2) objects, the velocity of the bulge stars increases and the AM of the bulge is almost conserved, whereas at lower B/T values, the velocity of the bulge stars decreases and the AM of the bulge reduces. The correlation between the evolution of the AM and B/T suggests that bulge formation and disc formation are closely linked and cannot be treated as independent processes.",
keywords = "Galaxies: bulges, Galaxies: evolution, Galaxies: formation, Galaxies: kinematics and dynamics, Galaxies: spiral, Methods: numerical",
author = "Liang Wang and Danail Obreschkow and Lagos, {Claudia Del P.} and Sweet, {Sarah M.} and Deanne Fisher and Karl Glazebrook and Macci{\`o}, {Andrea V.} and Dutton, {Aaron A.} and Xi Kang",
year = "2019",
month = "2",
day = "1",
doi = "10.1093/mnras/sty3010",
language = "English",
volume = "482",
pages = "5477--5491",
journal = "Monthly Notices of the Royal Astronomical Society",
issn = "0035-8711",
publisher = "OXFORD UNIV PRESS UNITED KINGDOM",
number = "4",

}

Angular momentum evolution of bulge stars in disc galaxies in NIHAO. / Wang, Liang; Obreschkow, Danail; Lagos, Claudia Del P.; Sweet, Sarah M.; Fisher, Deanne; Glazebrook, Karl; Macciò, Andrea V.; Dutton, Aaron A.; Kang, Xi.

In: Monthly Notices of the Royal Astronomical Society, Vol. 482, No. 4, 01.02.2019, p. 5477-5491.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Angular momentum evolution of bulge stars in disc galaxies in NIHAO

AU - Wang, Liang

AU - Obreschkow, Danail

AU - Lagos, Claudia Del P.

AU - Sweet, Sarah M.

AU - Fisher, Deanne

AU - Glazebrook, Karl

AU - Macciò, Andrea V.

AU - Dutton, Aaron A.

AU - Kang, Xi

PY - 2019/2/1

Y1 - 2019/2/1

N2 - We study the origin of bulge stars and their angular momentum (AM) evolution in 10 spiral galaxies with baryonic masses above 1010 M in the Numerical Investigation of a Hundred Astrophysical Objects galaxy formation simulations. The simulated galaxies are in good agreement with observations of the relation between the specific AM and mass of the baryonic component and the stellar bulge-to-total ratio (B/T). We divide the star particles at z = 0 into disc and bulge components using a hybrid photometric/kinematic decomposition method that identifies all the central mass above an exponential disc profile as the ‘bulge’. By tracking the bulge star particles back in time, we find that on average 95 per cent of the bulge stars formed in situ, 3 per cent formed ex situ in satellites of the same halo, and only 2 per cent formed ex situ in external galaxies. The evolution of the AM distribution of the bulge stars paints an interesting picture: The higher the final B/T, the more the specific AM remains preserved during the bulge formation. In all cases, bulge stars migrate significantly towards the central region, reducing their average galactocentric radius by roughly a factor 2, independently of the final B/T value. However, in the higher B/T ( 0.2) objects, the velocity of the bulge stars increases and the AM of the bulge is almost conserved, whereas at lower B/T values, the velocity of the bulge stars decreases and the AM of the bulge reduces. The correlation between the evolution of the AM and B/T suggests that bulge formation and disc formation are closely linked and cannot be treated as independent processes.

AB - We study the origin of bulge stars and their angular momentum (AM) evolution in 10 spiral galaxies with baryonic masses above 1010 M in the Numerical Investigation of a Hundred Astrophysical Objects galaxy formation simulations. The simulated galaxies are in good agreement with observations of the relation between the specific AM and mass of the baryonic component and the stellar bulge-to-total ratio (B/T). We divide the star particles at z = 0 into disc and bulge components using a hybrid photometric/kinematic decomposition method that identifies all the central mass above an exponential disc profile as the ‘bulge’. By tracking the bulge star particles back in time, we find that on average 95 per cent of the bulge stars formed in situ, 3 per cent formed ex situ in satellites of the same halo, and only 2 per cent formed ex situ in external galaxies. The evolution of the AM distribution of the bulge stars paints an interesting picture: The higher the final B/T, the more the specific AM remains preserved during the bulge formation. In all cases, bulge stars migrate significantly towards the central region, reducing their average galactocentric radius by roughly a factor 2, independently of the final B/T value. However, in the higher B/T ( 0.2) objects, the velocity of the bulge stars increases and the AM of the bulge is almost conserved, whereas at lower B/T values, the velocity of the bulge stars decreases and the AM of the bulge reduces. The correlation between the evolution of the AM and B/T suggests that bulge formation and disc formation are closely linked and cannot be treated as independent processes.

KW - Galaxies: bulges

KW - Galaxies: evolution

KW - Galaxies: formation

KW - Galaxies: kinematics and dynamics

KW - Galaxies: spiral

KW - Methods: numerical

UR - http://www.scopus.com/inward/record.url?scp=85061075862&partnerID=8YFLogxK

U2 - 10.1093/mnras/sty3010

DO - 10.1093/mnras/sty3010

M3 - Article

VL - 482

SP - 5477

EP - 5491

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 4

ER -