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Title: CONSTRAINTS ON MACHO DARK MATTER FROM COMPACT STELLAR SYSTEMS IN ULTRA-FAINT DWARF GALAXIES

Abstract

I show that a recently discovered star cluster near the center of the ultra-faint dwarf galaxy Eridanus II provides strong constraints on massive compact halo objects (MACHOs) of ≳5 M {sub ⊙} as the main component of dark matter. MACHO dark matter will dynamically heat the cluster, driving it to larger sizes and higher velocity dispersions until it dissolves into its host galaxy. The stars in compact ultra-faint dwarf galaxies themselves will be subject to the same dynamical heating; the survival of at least 10 such galaxies places independent limits on MACHO dark matter of masses ≳10 M {sub ⊙}. Both Eri II’s cluster and the compact ultra-faint dwarfs are characterized by stellar masses of just a few thousand M {sub ⊙} and half-light radii of 13 pc (for the cluster) and ∼30 pc (for the ultra-faint dwarfs). These systems close the ∼20–100 M {sub ⊙} window of allowed MACHO dark matter and combine with existing constraints from microlensing, wide binaries, and disk kinematics to rule out dark matter composed entirely of MACHOs from ∼10{sup −7} M {sub ⊙} up to arbitrarily high masses.

Authors:
 [1]
  1. Institute for Advanced Study, Einstein Dr., Princeton, NJ (United States)
Publication Date:
OSTI Identifier:
22654291
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 824; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; DISPERSIONS; GALAXIES; HEATING; LIMITING VALUES; MASS; NONLUMINOUS MATTER; STAR CLUSTERS; STARS; VELOCITY; VISIBLE RADIATION

Citation Formats

Brandt, Timothy D. CONSTRAINTS ON MACHO DARK MATTER FROM COMPACT STELLAR SYSTEMS IN ULTRA-FAINT DWARF GALAXIES. United States: N. p., 2016. Web. doi:10.3847/2041-8205/824/2/L31.
Brandt, Timothy D. CONSTRAINTS ON MACHO DARK MATTER FROM COMPACT STELLAR SYSTEMS IN ULTRA-FAINT DWARF GALAXIES. United States. doi:10.3847/2041-8205/824/2/L31.
Brandt, Timothy D. 2016. "CONSTRAINTS ON MACHO DARK MATTER FROM COMPACT STELLAR SYSTEMS IN ULTRA-FAINT DWARF GALAXIES". United States. doi:10.3847/2041-8205/824/2/L31.
@article{osti_22654291,
title = {CONSTRAINTS ON MACHO DARK MATTER FROM COMPACT STELLAR SYSTEMS IN ULTRA-FAINT DWARF GALAXIES},
author = {Brandt, Timothy D.},
abstractNote = {I show that a recently discovered star cluster near the center of the ultra-faint dwarf galaxy Eridanus II provides strong constraints on massive compact halo objects (MACHOs) of ≳5 M {sub ⊙} as the main component of dark matter. MACHO dark matter will dynamically heat the cluster, driving it to larger sizes and higher velocity dispersions until it dissolves into its host galaxy. The stars in compact ultra-faint dwarf galaxies themselves will be subject to the same dynamical heating; the survival of at least 10 such galaxies places independent limits on MACHO dark matter of masses ≳10 M {sub ⊙}. Both Eri II’s cluster and the compact ultra-faint dwarfs are characterized by stellar masses of just a few thousand M {sub ⊙} and half-light radii of 13 pc (for the cluster) and ∼30 pc (for the ultra-faint dwarfs). These systems close the ∼20–100 M {sub ⊙} window of allowed MACHO dark matter and combine with existing constraints from microlensing, wide binaries, and disk kinematics to rule out dark matter composed entirely of MACHOs from ∼10{sup −7} M {sub ⊙} up to arbitrarily high masses.},
doi = {10.3847/2041-8205/824/2/L31},
journal = {Astrophysical Journal Letters},
number = 2,
volume = 824,
place = {United States},
year = 2016,
month = 6
}
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