Black Hole Mass Spectrum


Astronomy research
  Software Infrastructure:
     My instruments
  White dwarf pulsations:
     12C(α,γ) & overshooting
     Probe of 12C(α,γ)16O
     Impact of 22Ne
     Impact of ν cooling
     Variable white dwarfs
     MC reaction rates
  White dwarf supernova:
     Stable nickel production
     Remnant metallicities
     Colliding white dwarfs
     Merging white dwarfs
     Ignition conditions
     Metallicity effects
     Central density effects
     Detonation density
     Tracer particle burning
     Subsonic burning fronts
     Supersonic fronts
     W7 profiles
  Massive stars:
     Pop III with HST/JWST
     Rotating progenitors
     3D evolution to collapse
     MC reaction rates
     Pre-SN variations
  Massive star supernova:
     Yields of radionuclides
     26Al & 60Fe
     44Ti, 60Co & 56Ni
     SN 1987A light curve
     Constraints on Ni/Fe
     An r-process
     Effects of 12C +12C
  Neutron Stars and Black Holes:
     Black Hole spectrum
     Mass Gap with LVK
     Compact object IMF
     He burn neutron stars
  Neutrino Emission:
     Neutrino emission from stars
     Identifying the Pre-SN
     Neutrino HR diagram
     Pre-SN Beta Processes
     Pre-SN neutrinos
     Hypatia catalog
     SAGB stars
     Nugrid Yields I
     He shell convection
     BBFH at 40 years
     γ-rays within 100 Mpc
     Iron Pseudocarbynes
  Pre-Solar Grains:
     C-rich presolar grains
     SiC Type U/C grains
     Grains from massive stars
     Placing the Sun
     SiC Presolar grains
  Chemical Evolution:
     Radionuclides in 2020s
     Zone models H to Zn
     Mixing ejecta
  Thermodynamics & Networks
     Skye EOS
     Helm EOS
     Five EOSs
     Equations of State
     12C(α,γ)16O Rate
     Proton-rich NSE
     Reaction networks
     Bayesian reaction rates
  Verification Problems:
     Validating an astro code
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2024 MESA Classroom
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Contact: F.X.Timmes
my one page vitae,
full vitae,
research statement, and
teaching statement.
Resolving The Peak Of The Black Hole Mass Spectrum (2022)

Gravitational wave (GW) detections of binary black hole (BH) mergers have begun to sample the cosmic BH mass distribution. The evolution of single stellar cores predicts a gap in the BH mass distribution due to pair-instability supernova (PISN). Determining the upper and lower edges of the BH mass gap can be useful for interpreting GW detections from merging BHs. In this article We use MESA to evolve single, non-rotating, massive helium cores with a metallicity of $Z = 10^{-5}$ until they either collapse to form a BH or explode as a PISN without leaving a compact remnant. We calculate the boundaries of the lower BH mass gap for S-factors in the range S(300 keV) = (77,203) keV b, corresponding to the $\pm 3\sigma$ uncertainty in our high resolution tabulated $^{12}$C($\alpha$,$\gamma$)$^{16}$O reaction rate probability distribution function. We extensively test the temporal and mass resolution to resolve the theoretical peak of the BH mass spectrum across the BH mass gap. We explore the convergence with respect to convective mixing and nuclear burning, finding that significant time resolution is needed to achieve convergence. We also test adopting a minimum diffusion coefficient to help lower resolution models reach convergence. We establish a new lower edge of the upper mass gap as M$_{\rm lower}$ $\simeq$ 60$^{+32}_{-14}$ M$_{\odot}$ from the $\pm 3\sigma$ uncertainty in the $^{12}$C($\alpha$,$\gamma$)$^{16}$O rate. We explore the effect of a larger 3-$\alpha$ rate on the lower edge of the upper mass gap, finding M$_{\rm lower}$ $\simeq$ 69$^{+34}_{-18}$ M$_{\odot}$. We compare our results with BHs reported in the Gravitational-Wave Transient Catalog.

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Observing Intermediate-mass Black Holes and the Upper Stellar-mass gap with LIGO and Virgo (2022)

In this article we probe the mass function of intermediate-mass black holes (IMBHs) wherein we also include BHs in the upper mass gap ∼60 - 130 M$_{\odot}$. Employing the projected sensitivity of the upcoming LIGO and Virgo fourth observing (O4) run, we perform Bayesian analysis on quasi-circular non-precessing, spinning IMBH binaries (IMBHBs) with total masses 50 - 500 M$_\odot$, mass ratios 1.25, 4, and 10, and dimensionless spins up to 0.95, and estimate the precision with which the source-frame parameters can be measured. We find that, at 2$\sigma$, the mass of the heavier component of IMBHBs can be constrained with an uncertainty of ∼10 - 40% at a signal-to-noise ratio of 20. Focusing on the stellar-mass gap with new tabulations of the $^{12}$C($\alpha$,$\gamma$)$^{16}$O reaction rate and its uncertanties, we evolve massive helium core stars using MESA, to establish the lower and upper edge of the mass gap as ∼59$^{+34}_{-13}$ M$_{\odot}$ and ∼139$^{+30}_{-14}$ M$_{\odot}$ respectively, where the error bars give the mass range that follows from the ±3$\sigma$ uncertainty in the $^{12}$C($\alpha$,$\gamma$)$^{16}$O nuclear reaction rate. We find that high resolution of the tabulated reaction rate and fine temporal resolution are necessary to resolve the peak of the BH mass spectrum. We then study IMBHBs with components lying in the mass gap and show that the O4 run will be able to robustly identify most such systems. Finally, we re-analyse GW190521 with a state-of-the-art aligned-spin waveform model, finding that the primary mass lies in the mass gap with 90% credibility.

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