Verifying Stellar Black Hole Candidates Using Radial Velocity Method

Abstract

This study gives a quick introduction to stellar black holes, explores the drawbacks of identifying the unseen companion only by analysing the X-ray emission from X-ray binaries, derives the radial velocity method, and tests it using two black hole candidates. The dark companion in A0620-00 has a radial velocity semi-amplitude of 459.613.91kms±⁻¹ M⊙, and its computed mass is 3.180.16± M⊙, above the 3 M⊙ Tolman–Oppenheimer–Volkoff limit on neutron star mass. With the two recorded X-ray outbursts, its identity as a black hole is largely verified. On the other hand, the dark companion in LMC X-3 has a radial velocity semi-amplitude of 219.310.47±kms⁻¹ and a computed mass of 6.980.56± M⊙, exceeding the upper mass limit of neutron star. Its powerful and very fluctuating X-ray emission is supported by observations, and thus helps to basically corroborate that it is indeed a black hole. In the search for black holes, the two methods presented to ascertain the nature of the dark companion are both essential and needed. After classifying the partners and adding them to the list of potential black hole candidates using X-ray emission analysis, the mass of the companion can be confirmed by calculating the star’s radial velocity. Nonetheless, identification errors are not uncommon; the computed mass varies within an unavoidable range, giving rise to disparate findings. Future research may compare the differences between black hole binaries and neutron star binaries and look for evidence to increase the veracity and trustworthiness of the results.