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

By Timothy D. Brandt. 2016

296 citations recorded by the source corpus.

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⊙ 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⊙. Both Eri II’s cluster and the compact ultra-faint dwarfs are characterized by stellar masses of just a few thousand M⊙ 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⊙ 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 ∼10−7M⊙ up to arbitrarily high masses.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/077603cbf56c8bc2651d85794e58978204926599

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In Astronomy and Astrophysics

1. B. Carr
2. Florian Kuhnel
3. Juan García-Bellido
4. J. Silk
5. Marco Peloso
6. C. Unal
7. A. Riotto
8. G. Franciolini

In Instrumentation

1. J. Silk
2. B. Carr
3. Risa Wechsler
4. Florian Kuhnel
5. Joshua A. Frieman
6. L. Strigari
7. A. Peter
8. H. Veermae

Citations in the corpus

• Primordial black hole dark matter from single field inflation (2017, background): “Specifically, the dynamics of a star cluster in Eridanus II [24] and stars in other dwarf galaxies [25] disfavour the possibility that the DM of the Universe could be in the form of BHs of a few tens ofM .”
• Two populations of LIGO-Virgo black holes (2020, methodology): “Other shaded regions in figure 5 show the constraints from microlensing results from EROS [79], OGLE [80], and MACHO [81], lensing of type Ia supernovae (SNe) [82], survival of a stars in dwarf galaxies (Seg I and Eri II) [83, 84], distribution of wide binaries (WB) [85], Lyman-α forest data [86, 87”
• Gravitational probes of dark matter physics (2017, background): “the stellar distribution within the Milky Way’s satellite population further exclude PBH as a significant contributor to the dark matter budget for PBH masses greater than a few times 10(2)M [110, 111, 112, 113].”
• Primordial black holes confront LIGO/Virgo data: current situation (2020, background): “Dynamical constraints involve disruption of wide binaries [97], and survival of star clusters in Eridanus II [98] and Segue I [99] at small redshifts.”
• A Brief Review on Primordial Black Holes as Dark Matter (2021, background): “Making use of these effects, tight bounds have been obtained at fPBH ∼ 10− 3 forMPBH ∼ 104 M⊙, weakening at lower masses down to fPBH ≲ 1 for MPBH ∼ 10M⊙ (Brandt, 2016).”
• Generating PBHs and small-scale GWs in two-field models of inflation (2020, background): “lactic radiation (EG bkg) [70], long-livedness of white dwarfs (WD) [71], microlensing by the Subaru Hyper Suprime-Cam (HSC) [72], Kepler [73], EROS [74], survival of ultra-faint dwarf galaxies (UFD) [75] and the accretion on the CMB [76{79]. We do not show constraints from the presence of neutron s”
• Gravitational wave signatures of inflationary models from Primordial Black Hole dark matter (2017, background): “1037 is mostly constrained by the existence of a stellar cluster near the center of ultra-faint dwarf galaxy (“UFD”) Eridanus II [50], which has been shown in [51] to be weakened if there is an intermediate mass black hole of a few thousand solar masses at its center, as the clustered PBH scenario p”