LMC X-3

LMC X-3

Location of LMC X-3 from ESASky (pointed in red).
Observation data
Epoch J2000      Equinox J2000
Constellation Dorado
Right ascension 05h 38m 56s
Declination −64° 05′ 03″
Apparent magnitude (V) 16.7
Characteristics
Evolutionary stage Main-sequence (A)
Black hole (B)
Spectral type BH + B2.5Ve
Astrometry
Distance165,000[1] ly
(50,589 pc)
Orbit
Primarymain-sequence star
Nameblack hole
Period (P)1.70481 days
Semi-major axis (a)11000000 km[1]
Eccentricity (e)0.22 ± 0.4[2]
Inclination (i)69.8° ± 0.84[3]°
Semi-amplitude (K2)
(secondary)		256.7 ± 4.9 km/s
Details[4]
A
Mass3.63 ± 0.57 M☉
Radius4.4 R☉
B
Mass6.98 ± 0.56 M☉
Other designations
LMC X-3, RX J0538.9-6405, 2MAXI J0539-640, 2XMM J053856.5-640503, Gaia DR3 4757068874690668160[5]
Database references
SIMBADdata

LMC X-3 is a high-mass X-ray binary (HMXB) system located in the Large Magellanic Cloud (LMC), a satellite galaxy of the Milky Way approximately 165,000 light-years (50.5 kiloparsecs) away.[4] The system consists of a stellar-mass black hole accreting material from a B-type main-sequence companion star, producing intense X-ray emission via a hot accretion disk. LMC X-3 is one of the most studied extragalactic black hole binaries due to its brightness and variability.[5][6][7]

Discovery

Black Hole

LMC X-3 was first identified in 1971 by the Uhuru satellites lead by Leong et al.[8] and discovered as a bright X-ray source in the Large Magellanic Cloud. This was identified as a black hole in 1983 by Anne Cowley et al. using dynamic observations along with the companion B-star.[9]

Star

The companion of the LMC X-3 black hole was located on 1975 by Rick Warren and Jeffrey Penfold when they saw an optical counterpart as a OB star in the X-ray error circle.[10] In 1983, this was confirmed by Cowley et al. by using spectral and spectroscopic observation of LMC X-3.[8]

Characteristics

LMC X-3 comprises a black hole and a B-type companion star, classified as B2.5Ve. The companion, with a surface temperature significantly hotter than the Sun’s, transfers mass to the black hole via Roche-lobe overflow, forming an accretion disk that emits X-rays up to 10,000 times the Sun’s total luminosity.[11]

Orbital Parameters

The system has an orbital period of approximately 1.70481 days, with a separation of about 7 million miles (11 million kilometers). The orbit is inclined at 68° (+2°/−3°), preventing eclipses. The companion’s radial velocity semi-amplitude is 256.7 ± 4.9 km/s, yielding a mass function of ~2.3 solar masses. Optical light curves show double-humped profiles due to the companion’s ellipsoidal distortion.[12][13]

Variability

LMC X-3 is notable for its persistent yet highly variable nature, often remaining in soft spectral states dominated by thermal disk emission, making it ideal for testing accretion disk models. It exhibits long-term intensity variations on 100–300 day timescales and enters anomalous low states (ALS) lasting 80+ days, during which X-ray and UV brightness drops significantly, with reduced variability. These ALS events, observed multiple times, are likely driven by changes in mass accretion rate from the companion, with X-ray lags of about 8 days during state transitions. The inner disk radius remains remarkably constant across observations, supporting reliable spin measurements via continuum fitting.[14][15][16][17]

Spin and polarization

The black hole's spin parameter is low, estimated at ~0.2 using X-ray continuum fitting. In 2023, IXPE detected X-ray polarization with a polarization degree of 3.2% ± 0.6% and a polarization angle of −42° ± 6° in the 2–8 keV band, setting an upper spin limit of a < 0.7 at 90% confidence. Polarization increases slightly with energy, consistent with other soft-state black hole binaries. Simultaneous NICER and NuSTAR observations confirmed the soft-state nature and spin estimates.[18]

Formation and Evolution

Evolutionary models suggest LMC X-3 formed from a zero-age main-sequence binary, evolving through a supernova explosion of the primary star, with the current phase involving stable mass transfer. Its proximity to the transient/persistent divide among black hole X-ray binaries makes it a key system for understanding accretion physics and black hole formation in low-metallicity environments like the LMC.[19]

See also

References

  1. ^ a b "LMC X-3 Fact Sheet". StarDate's Black Hole Encyclopedia.
  2. ^ Sørensen, Mads; Fragos, Tassos; Steiner, James F.; Antoniou, Vallia; Meynet, Georges; Dosopoulou, Fani (January 2017). "Unraveling the formation history of the black hole X-ray binary LMC X-3 from the zero age main sequence to the present". Astronomy & Astrophysics. 597: A12. arXiv:1605.06808. Bibcode:2017A&A...597A..12S. doi:10.1051/0004-6361/201628979. ISSN 0004-6361.
  3. ^ Orosz, Jerome A.; Steiner, James F.; McClintock, Jeffrey E.; Buxton, Michelle M.; Bailyn, Charles D.; Steeghs, Danny; Guberman, Alec; Torres, Manuel A. P. (October 2014). "The mass of the black hole in LMC X-3". The Astrophysical Journal. 794 (2): 154. arXiv:1402.0085. Bibcode:2014ApJ...794..154O. doi:10.1088/0004-637X/794/2/154. ISSN 1538-4357.
  4. ^ a b Orosz, Jerome A.; Steiner, James F.; McClintock, Jeffrey E.; Buxton, Michelle M.; Bailyn, Charles D.; Steeghs, Danny; Guberman, Alec; Torres, Manuel A. P. (2014-10-06). "The Mass of the Black Hole in LMC X-3". The Astrophysical Journal. 794 (2): 154. arXiv:1402.0085. Bibcode:2014ApJ...794..154O. doi:10.1088/0004-637X/794/2/154. ISSN 1538-4357.
  5. ^ a b "LMC X-3". SIMBAD. Retrieved 21 September 2025.
  6. ^ Torpin, Trevor J.; Boyd, Patricia T.; Smale, Alan P.; Valencic, Lynne A. (2017-10-27). "Unusual Black Hole Binary LMC X-3: A Transient High-Mass X-Ray Binary That Is Almost Always On?". The Astrophysical Journal. 849 (1): 32. Bibcode:2017ApJ...849...32T. doi:10.3847/1538-4357/aa8f96. ISSN 0004-637X.
  7. ^ Nowak, M. A.; Wilms, J.; Heindl, W. A.; Pottschmidt, K.; Dove, J. B.; Begelman, M. C. (2000-08-08), "A good long look at the black hole candidates LMC X-1 and LMC X-3", Monthly Notices of the Royal Astronomical Society, 320 (3): 316–326, arXiv:astro-ph/0005487, doi:10.1046/j.1365-8711.2001.03984.x
  8. ^ a b Steiner, James F.; McClintock, Jeffrey E.; Remillard, Ronald A.; Gou, Lijun; Yamada, Shin'ya; Narayan, Ramesh (2010). "The Constant Inner-Disk Radius of LMC X-3: A Basis for Measuring Black Hole Spin". The Astrophysical Journal. 718 (2): L117–L121. arXiv:1006.5729. Bibcode:2010ApJ...718L.117S. doi:10.1088/2041-8205/718/2/L117.
  9. ^ Orosz, Jerome A.; Steiner, James F.; McClintock, Jeffrey E.; Buxton, Michelle M.; Bailyn, Charles D.; Steeghs, Danny; Guberman, Alec; Torres, Manuel A. P. (2014). "The Mass of the Black Hole in LMC X-3". The Astrophysical Journal. 794 (2): 154. arXiv:1402.0085. Bibcode:2014ApJ...794..154O. doi:10.1088/0004-637X/794/2/154.
  10. ^ Val-Baker, A. K. F.; Norton, A. J.; Negueruela, I. (2007). "The mass of the black hole in LMC X-3". The Multicolored Landscape of Compact Objects and Their Explosive Origins. AIP Conference Proceedings. 924: 530–533. arXiv:1608.01187. Bibcode:2007AIPC..924..530V. doi:10.1063/1.2774906.
  11. ^ "LMC X-3 Fact Sheet - StarDate's Black Hole Encyclopedia". blackholes.stardate.org. Retrieved 2025-09-21.
  12. ^ Cowley, A. P.; Crampton, D.; Hutchings, J. B.; Remillard, R.; Penfold, J. E. (September 1983). "Discovery of a massive unseen star in LMC X-3". The Astrophysical Journal. 272: 118. Bibcode:1983ApJ...272..118C. doi:10.1086/161267. ISSN 0004-637X.
  13. ^ Gräff, Dominik (2020-11-02). "Messung der Masse des Schwarzen Loches in LMC X-3 (Measuring the mass of the black hole in LMC X-3)". arXiv:2011.01230 [astro-ph.HE].
  14. ^ Nowak, M. A.; Wilms, J.; Heindl, W. A.; Pottschmidt, K.; Dove, J. B.; Begelman, M. C. (2000). "A good long look at the black hole candidates LMC X-1 and LMC X-3". Monthly Notices of the Royal Astronomical Society. 320 (3): 316–326. arXiv:astro-ph/0005487. doi:10.1046/j.1365-8711.2001.03984.x.
  15. ^ Straub, O.; Bursa, M.; Sa¸dowski, A.; Steiner, J. F.; Abramowicz, M. A.; Kluźniak, W.; McClintock, J. E.; Narayan, R.; Remillard, R. A. (2011-09-01). "Testing slim-disk models on the thermal spectra of LMC X-3". Astronomy & Astrophysics. 533: A67. arXiv:1106.0009. Bibcode:2011A&A...533A..67S. doi:10.1051/0004-6361/201117385. ISSN 0004-6361.
  16. ^ Steiner, James F.; McClintock, Jeffrey E.; Remillard, Ronald A.; Gou, Lijun; Yamada, Shin'ya; Narayan, Ramesh (2010). "The Constant Inner-Disk Radius of LMC X-3: A Basis for Measuring Black Hole Spin". The Astrophysical Journal. 718 (2): L117–L121. arXiv:1006.5729. Bibcode:2010ApJ...718L.117S. doi:10.1088/2041-8205/718/2/L117.
  17. ^ Torpin, Trevor J.; Boyd, Patricia T.; Smale, Alan P.; Valencic, Lynne A. (2017-11-01). "Unusual Black Hole Binary LMC X-3: A Transient High-mass X-Ray Binary That Is Almost Always On?". The Astrophysical Journal. 849 (1): 32. Bibcode:2017ApJ...849...32T. doi:10.3847/1538-4357/aa8f96. ISSN 0004-637X.
  18. ^ Svoboda, Jiří; Dovčiak, Michal; Steiner, James F.; Muleri, Fabio; Ingram, Adam; Yilmaz, Anastasiya; Cavero, Nicole Rodriguez; Marra, Lorenzo; Poutanen, Juri (2023-09-19). "First X-Ray Polarization Measurement Confirms the Low Black Hole Spin in LMC X-3". The Astrophysical Journal. 960: 3. arXiv:2309.10813. doi:10.3847/1538-4357/ad0842.
  19. ^ Sørensen, Mads; Fragos, Tassos; Steiner, James F.; Antoniou, Vallia; Meynet, Georges; Dosopoulou, Fani (2017-01-01). "Unraveling the formation history of the black hole X-ray binary LMC X-3 from the zero age main sequence to the present". Astronomy & Astrophysics. 597: A12. arXiv:1605.06808. Bibcode:2017A&A...597A..12S. doi:10.1051/0004-6361/201628979. ISSN 0004-6361.
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