Formation of LISA Black Hole Binaries in Merging Dwarf Galaxies: The Imprint of Dark Matter

Επιστημονική δημοσίευση - Άρθρο Περιοδικού uoadl:3069173 9 Αναγνώσεις

Μονάδα:
Ερευνητικό υλικό ΕΚΠΑ
Τίτλος:
Formation of LISA Black Hole Binaries in Merging Dwarf Galaxies: The Imprint of Dark Matter
Γλώσσες Τεκμηρίου:
Αγγλικά
Περίληψη:
Theoretical models for the expected merger rates of intermediate-mass black holes (IMBHs) are vital for planned gravitational-wave detection experiments such as the Laser Interferometer Space Antenna (LISA). Using collisionless N-body simulations of dwarf galaxy (DG) mergers, we examine how the orbital decay of IMBHs and the efficiency of IMBH binary formation depend on the central dark matter (DM) density profile of the merging DGs. Specifically, we explore various asymptotic inner slopes γ of the DG's DM density distribution, ranging from steep cusps (γ = 1) to shallower density profiles (γ < 1), motivated by well-known baryonic-feedback effects as well as by DM models that differ from cold DM at the scales of DGs. We find that the inner DM slope is crucial for the formation (or lack thereof) of an IMBH binary; only mergers between DGs with cuspy DM profiles (γ = 1) are favorable to forming a hard IMBH binary, whereas when γ < 1 the IMBHs stall at a separation of 50-100 pc. Consequently, the rate of LISA signals from IMBH coalescence will be determined by the fraction of DGs with a cuspy DM profile. Conversely, the LISA event rates at IMBH mass scales offer in principle a novel way to place constraints on the inner structure of DM halos in DGs and address the core-cusp controversy. We also show that, with spatial resolutions of ∼0.1 kpc, as often adopted in cosmological simulations, all IMBHs stall, independent of γ. This suggests caution should be taken when employing cosmological simulations of galaxy formation to study BH dynamics in DGs. © 2018. The American Astronomical Society. All rights reserved.
Έτος δημοσίευσης:
2018
Συγγραφείς:
Tamfal, T.
Capelo, P.R.
Kazantzidis, S.
Mayer, L.
Potter, D.
Stadel, J.
Widrow, L.M.
Περιοδικό:
The Astrophysical Journal Letters
Εκδότης:
INSTITUTE OF PHYSICS PUBLISHING
Τόμος:
864
Αριθμός / τεύχος:
1
Επίσημο URL (Εκδότης):
DOI:
10.3847/2041-8213/aada4b
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