Bullet Group

The Bullet Group (SL2S J08544-0121) is a newly merging group of galaxies, a merger between two galaxy groups to form a new larger one, that recently had a high speed collision between the two component groups. The group exhibits separation between its dark matter and baryonic matter components, and the galaxies occurring in two clumps, while the gas expanding into a billowing cloud encompassing all three clumps. As of 2014, it is one of the few galaxy clusters known to show separation between the dark matter and baryonic matter components. The group is named after the Bullet Cluster, a similar merging galaxy cluster, except on a smaller scale, being of groups instead of clusters.[2][3] The bimodal distribution of galaxies was found at discovery in 2008. The galaxy group is a gravitational lens and strongly lenses a more distant galaxy behind it, at z=~1.2[3][4]

Not to be confused with Bullet Cluster or Bullet Galaxy.

Bullet Group
Observation data (Epoch J2000.0[1])
Constellation(s)	Hydra
Right ascension	08^h 54^m 46.5480^s [1]
Declination	−01° 21′ 37.262″ [1]
Redshift	0.351[1]
Binding mass	(2.4±0.6)×10^14 [2] M☉
Other designations
Bullet Group,[3] SL2S J08544-0121[4]

Characteristics

As of 2014, the group is the smallest mass object to exhibit separation between its dark matter and baryonic matter components.[2]

The galaxy group is dominated by one elliptical galaxy, situated in one of the two concentrations, while the other node has two large bright galaxies, which do not dominate the group.[4] The group has an apparent radius of 200 arcseconds, and a virial radius of 1 megaparsec.[5]

See also

• Musket Ball Cluster

References

1. "[LCG2009] SL2S Group J08544-0121 -- Group of Galaxies". SIMBAD. Retrieved 18 July 2014.
2. F. Gastaldello; M. Limousin; G. Foëx; R. P. Muñoz; T. Verdugo; V. Motta; et al. (22 Apr 2014). "Dark matter-baryons separation at the lowest mass scale: the Bullet Group". Monthly Notices of the Royal Astronomical Society: Letters (published July 2014). 442 (1): L76–L80. arXiv:1404.5633. Bibcode:2014MNRAS.442L..76G. doi:10.1093/mnrasl/slu058.
3. XMM-Newton (6 June 2014). "Cosmic collision in the Bullet Group". European Space Agency.
4. M. Limousin; R. Cabanac; R. Gavazzi; J.-P. Kneib; V. Motta; J. Richard; et al. (4 December 2008). "A New Window of Exploration in the Mass Spectrum: Strong Lensing by Galaxy Groups in the SL2S". Astronomy and Astrophysics (published August 2009). 502 (2): 445–456. arXiv:0812.1033. Bibcode:2009A&A...502..445L. doi:10.1051/0004-6361/200811473.
5. Muñoz, R. P.; Motta, V.; Verdugo, T.; Garrido, F.; Limousin, M.; Padilla, N.; et al. (11 December 2012). "Dynamical analysis of strong-lensing galaxy groups at intermediate redshift". Astronomy & Astrophysics (published April 2013). 552: 18. arXiv:1212.2624. Bibcode:2013A&A...552A..80M. doi:10.1051/0004-6361/201118513. A80.