Number Of Black Holes Research Articles

MOCCA-Survey Database: extra galactic globular clusters – III. The population of black holes in Milky Way and Andromeda-like galaxies

ABSTRACT This work investigates the black hole (BH) population of globular clusters (GCs) in Milky Way- and Andromeda-like galaxies. We combine the population synthesis code MASinGa and the MOCCA-Survey Database I to infer the properties of GCs harbouring a stellar-mass BH subsystem (BHS), an intermediate-mass BH (IMBH), or neither of those. We find that the typical number of GCs with a BHS, an IMBH, or none become comparable in the galactic outskirts, whilst the inner galactic regions are dominated by GCs without a significant dark component. We retrieve the properties of binary BHs (BBHs) that have either merged in the last 3 Gyr or survived in their parent cluster until present-day. We find that around 80 per cent of the merging BBHs form due to dynamical interactions while the remaining originate from evolution of primordial binaries. The inferred merger rate for both in-cluster and ejected mergers is $1.0\!-\!23\, \, \rm {yr^{-1}\, Gpc^{-3}}$ in the local Universe, depending on the adopted assumptions. We find around 100–240 BBHs survive in GCs until present-day and are mostly concentrated in the inner few kpc of the galaxy. When compared with the field, GCs are at least two times more efficient in the formation of BHs and binaries containing at least one BH. Around 1000–3000 single BHs and 100–200 BBHs are transported into the galactic nucleus from infalling clusters over a time span of 12 Gyr. We estimate that the number of BHs and BBHs lurking in the star cluster to be about 1.4–2.2 × 104 and 700–1100, respectively.

Peginterferon beta-1a reduces the number of black holes evolved from acute MRI lesions in newly diagnosed patients with relapsing-remitting multiple sclerosis: A post hoc analysis ADVANCE

Introduction Chronic black holes (BHs) indicate severe tissue injury and are used as a biomarker of therapeutic outcomes in relapsing-remitting multiple sclerosis (RRMS). Objectives Evaluate the effect of peginterferon beta-1a every 2 weeks on the number of chronic BHs that evolve from acute lesions over 2 years. Patients and methods ADVANCE was a 2-year, double-blind phase 3 trial of peginterferon beta-1a in 1512 patients with RRMS. The number of BHs at week 96 that evolved from new/enlarging T2-weighted (NET2) lesions at 24 or 48 weeks or gadolinium-enhancing (Gd + ) lesions (at baseline, 24 weeks, or 48 weeks) were compared. The adjusted annualized relapse rate (ARR) by BH conversion status was also assessed. Results ADVANCE included 231 newly diagnosed and 281 non-newly diagnosed patients in the continuous-treatment group and 229 newly diagnosed and 271 non-newly diagnosed patients in the delayed-treatment group. At week 96, the continuous-treatment ITT patients had fewer BHs that evolved from NET2 lesions at week 24 or week 48 than the delayed-treatment ITT patients in both newly diagnosed (P Discussion The results are similar for the BHs that evolved from the Gd+ lesions detected at baseline, week 24 or week 48 in newly diagnosed (P Conclusion The lower risk of chronic BHs with peginterferon beta-1a therapy suggests the potential to provide treatment benefits to patients with RRMS by reducing long-term disability.

Predicting Stellar-mass Black Hole Populations in Globular Clusters

Abstract Recent discoveries of black hole (BH) candidates in Galactic and extragalactic globular clusters (GCs) have ignited interest in understanding how BHs dynamically evolve in a GC and the number of BHs ( N BH ) that may still be retained by today’s GCs. Numerical models show that even if stellar-mass BHs are retained in today’s GCs, they are typically in configurations that are not directly detectable. We show that a suitably defined measure of mass segregation (Δ) between, e.g., giants and low-mass main-sequence stars, can be an effective probe to indirectly estimate N BH in a GC aided by calibrations from numerical models. Using numerical models, including all relevant physics, we first show that N BH is strongly anticorrelated with Δ between giant stars and low-mass main-sequence stars. We apply the distributions of Δ versus N BH obtained from models to three Milky Way GCs to predict the N BH retained by them at present. We calculate Δ using the publicly available Advanced Camera for Surveys’ survey data for 47 Tuc, M10, and M22, all with identified stellar-mass BH candidates. Using these measured Δ and distributions of Δ versus N BH from models as calibration we predict distributions for N BH expected to be retained in these GCs. For 47 Tuc, M10, and M22 our predicted distributions peak at N BH ≈ 20, 24, and 50, whereas, within the 2σ confidence level, N BH can be up to ∼150, 50, and 200, respectively.