XTE J1118+480
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Ursa Major |
| Right ascension | 11h 18m 10.80s[1] |
| Declination | 48° 02′ 12.3″[1] |
| Apparent magnitude (V) | 12.25[2] |
| Details | |
| Black hole | |
| Mass | ~6 M☉ |
| B | |
| Mass | ~0.2 M☉ |
| Other designations | |
| Database references | |
| SIMBAD | data |
XTE J1118+480 is a low-mass X-ray binary in the constellation Ursa Major. It is a soft X-ray transient that most likely contains a black hole and is probably a microquasar.
Discovery
XTE J1118+480 was discovered using the All-Sky Monitor on the Rossi X-Ray Timing Explorer satellite after it produced an outburst during January 2008. XTE is the standard designation for objects discovered by this satellite. It is also catalogued as 2MASS J11181079+4802126 in Two-Micron All Sky Survey catalogue of infrared objects, and has been given the variable star designation KV Ursae Majoris.[3]
April-June outburst
Much of what is known about XTE J1118+480 comes from data collected during another outburst in 2000. The Rossi X-Ray Timing Explorer and the Advanced Research and Global Observation Satellite observed a quasi-periodic oscillation (QPO) from XTE J1118+480 as it evolved. The QPO is comparable to QPOs of other black-hole candidates.
Properties
The compact object in XTE J1118+480 has a mass greater than 6 M☉, so it is too massive to be a neutron star. The characteristics of radio emissions from XTE J1118+480 (Fender et al. 2001) suggest that it is a microquasar.[4]
Strangely, the companion star has a metal-rich composition of various metals such as magnesium, aluminium, calcium, iron, and nickel. Because of this observation, the black hole most likely was not formed from direct collapse of a massive star, but rather from the supernova of a metal-rich star. The two objects in the binary system were probably not born together as a supernova would likely eject the companion from the system.
The most likely theory as to how the black hole became part of the binary system is that XTE J1118+480 was formed in the central galactic halo. The black hole primary was the result of a "kick" from the supernova explosion of a massive star in the early galaxy and travelled through the galaxy and into the central galactic halo, becoming a binary system with its present-day companion.[3] If this theory is true, it may help to explain the supernova mechanism. The black hole in XTE J1118+480 is one of the only known examples of a black hole kick.
References
- 1 2 Cutri, R. M. (2003). "2MASS All-Sky Catalog of Point Sources". VizieR On-line Data Catalog. 2246. Bibcode:2003yCat.2246....0C.
- ↑ Liu, Q. Z.; Van Paradijs, J.; Van Den Heuvel, E. P. J. (2007). "A catalogue of low-mass X-ray binaries in the Galaxy, LMC, and SMC (Fourth edition)". Astronomy and Astrophysics. 469 (2): 807. Bibcode:2007A&A...469..807L. arXiv:0707.0544
. doi:10.1051/0004-6361:20077303. - 1 2 Khargharia, Juthika; Froning, Cynthia S.; Robinson, Edward L.; Gelino, Dawn M. (2013). "The Mass of the Black Hole in XTE J1118+480". The Astronomical Journal. 145: 21. Bibcode:2013AJ....145...21K. arXiv:1211.2786 . doi:10.1088/0004-6256/145/1/21.
- ↑ Vila, Gabriela S.; Romero, Gustavo E. (2011). "A leptonic/hadronic jet model for the low-mass microquasar XTE J1118+480". Proceedings of the International Astronomical Union. 6: 315. doi:10.1017/S1743921310016273.