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In numerous studies of the outer Galactic halo some evidence for accretion has been found. If the outer halo did form in part or wholly through merger events, we might expect to find coherent streams of stars and globular clusters following…

Astrophysics · Physics 2009-11-07 Christopher Palma , Steven R. Majewski , Kathryn V. Johnston

The galaxy formation process in the $\Lambda$-Cold Dark Matter scenario can be constrained from the analysis of stars in the Milky Way's halo system. We examine the variation of chemical abundances in distant halo stars observed by the…

We identify substructures of the Galactic halo using 3,003 type $ab$ RR Lyraes (RRab) with 6D position-velocity information from the SDSS, LAMOST, and Gaia EDR3. Based on the information, we define the separation of any two of the stars in…

Astrophysics of Galaxies · Physics 2022-06-01 F. Wang , H. -W. Zhang , X. -X. Xue , Y. Huang , G. -C. Liu , L. Zhang , C. -Q. Yang

We present an end-to-end description of the formation process of globular clusters (GCs) which combines a treatment for their formation and dynamical evolution within galaxy haloes with a state-of-the-art semi-analytic simulation of galaxy…

Late accretion models for formation of the Galactic halo require that many Galactic satellite galaxies have been cannibalised into the halo field. Comparison of the metallicity and age distribution function of stars in the surviving…

Astrophysics · Physics 2019-08-17 Gerard Gilmore , Xavier Hernandez , David Valls-Gabaud

We present chemodynamical links between the present-day Milky Way halo field star population and Galactic globular clusters (GCs) using a dataset that combines information from the $\rm{\it Gaia}$ space mission and the Sloan Digital Sky…

Astrophysics of Galaxies · Physics 2020-05-27 Michael Hanke , Andreas Koch , Zdenek Prudil , Eva K. Grebel , Ulrich Bastian

A possible relation between the high dispersion in metallicity of metal-poor halo stars and the minor merger processes in the history of the Galaxy is presented. The foreign populations of stars in the satellites through minor merger…

Astrophysics · Physics 2007-05-23 Y. Lu , K. S. Cheng , L. C. Deng

Galactic halo gas traces inflowing star formation fuel and feedback from a galaxy's disk and is therefore crucial to our understanding of galaxy evolution. In this review, we summarize the multi-wavelength observational properties and…

Astrophysics of Galaxies · Physics 2015-06-05 M. E. Putman , J. E. G. Peek , M. R. Joung

We estimated the galactic model parameters for a set of 20 intermediate-latitude fields with galactic longitudes 0<l<100 and 160<l<240, included in the currently available Data Release 6 (DR6) of SDSS, to explore their possible variation…

Astrophysics of Galaxies · Physics 2015-05-13 E. Yaz , S. Karaali

The outer halo regions of early-type galaxies carry key information about their past accretion history. However, spectroscopically probing the stellar component at such galactocentric radii is still challenging. Using Keck/DEIMOS, we have…

There is ample evidence in the Milky Way for globular cluster (GC) disruption. Hence one may expect that also part of the Galactic halo field stars may once have formed in GCs. We quantify the fraction of halo stars donated by GCs by…

Astrophysics of Galaxies · Physics 2019-05-15 Andreas Koch , Eva K. Grebel , Sarah L. Martell

Galaxies are thought to grow through accretion; as less massive galaxies are disrupted and merge over time, their debris results in diffuse, clumpy stellar halos enveloping the central galaxy. Here we present a study of the variation in the…

Astrophysics of Galaxies · Physics 2016-10-19 Allison Merritt , Pieter van Dokkum , Roberto Abraham , Jielai Zhang

The difference in density profiles of the contributions from different density peaks to dark matter halos results in certain expectations about the Milky Way's stellar halo. We cut our simulated halo stars into two populations: those…

Astrophysics · Physics 2009-03-19 C. B. Brook , D. Kawata , H. Martel , B. K. Gibson , E. Scannapieco

We use the Aquarius simulation series to study the imprint of assembly history on the structure of Galaxy-mass cold dark matter halos. Our results confirm earlier work regarding the influence of mergers on the mass density profile and the…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Jie Wang , J. F. Navarro , C. S. Frenk , S. D. M. White , V. Springel , A. Jenkins , A. Helmi , A. Ludlow , M. Vogelsberger

We explore the chemo-dynamical properties of a sample of very metal-poor (VMP) stars selected from the Hamburg/ESO survey, matched with Gaia EDR3, in the phase-space identified by the three integrals of motion ($L_z$, $E$, $I_3$). Disk and…

Astrophysics of Galaxies · Physics 2023-04-12 Daniela Carollo , Norbert Christlieb , Patricia B. Tissera , Emanuel Sillero

In the $\Lambda$-Cold Dark Matter model of the Universe, galaxies form in part through accreting satellite systems. Previous work have built an understanding of the signatures of these processes contained within galactic stellar halos. This…

[Abridged] Motivated by upcoming data from astrometric and spectroscopic surveys of the Galaxy, we explore the chemical abundance properties and phase-space distributions in hierarchically-formed stellar halo simulations set in a LambdaCDM…

Astrophysics · Physics 2008-11-26 Andreea S. Font , Kathryn V. Johnston , James S. Bullock , Brant E. Robertson

We exploit the [Mg/Mn]-[Al/Fe] chemical abundance plane to help identify nearby halo stars in the 14th data release from the APOGEE survey that have been accreted on to the Milky Way. Applying a Gaussian Mixture Model, we find a `blob' of…

Astrophysics of Galaxies · Physics 2020-02-12 Payel Das , Keith Hawkins , Paula Jofre

The stellar halos of galaxies encode their accretion histories. In particular, the median metallicity of a halo is determined primarily by the mass of the most massive accreted object. We use hydrodynamical cosmological simulations from the…

Astrophysics of Galaxies · Physics 2017-08-04 Kyle A. Oman , Else Starkenburg , Julio F. Navarro

A simple, 1-equation, galaxy formation model is applied to both the halo merger tree derived from a high-resolution dissipationless cosmological simulation and to 1/4 million Monte-Carlo halo merger trees. The galaxy formation model…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 Gary A. Mamon , Dylan Tweed , Trinh X. Thuan , Andrea Cattaneo
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