Physics Seminar Date : Wednesday, 10th April 2024 Time : 1:45 PM Venue: Lecture Hall 4 Discovery of a ‘lower mass gap’ black hole by LIGO Parthapratim Mahapatra Chennai Mathematical Institute. 10-04-24 Abstract Since the late 1990s, there have been claims about the existence of a mass gap (called ‘lower mass gap’) between the maximum neutron star mass and the minimum black hole mass (~3–5 M☉) based on dynamical mass measurements of Galactic X-ray binaries. Recently, the LIGO–Virgo–KAGRA collaboration announced the detection of a neutron star-black hole candidate GW230529 with a black hole mass between 2.5M☉– 4.5 M☉ at 90% credibility. GW230529 provides the best-yet evidence of compact objects existing in the purported ‘lower mass gap’, and urges change in the paradigm. One of the proposed mechanisms to produce black holes in the putative ‘lower mass gap’ is the hierarchical mergers of binary neutron star mergers in dense astrophysical environments or in hierarchical triple or quadruple systems. Invoking numerical relativity-based fitting formulas that map the masses, spins, and tidal deformability of the compact binary constituents to the mass and spin of the remnant black hole, we investigate the potential parents of GW230529 primary within the hierarchical merger scenario.
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