Bullet Group

{{distinguish|Bullet Cluster|Bullet Galaxy}}

{{refimprove|date=January 2015}}

{{sky|08|54|46.5480|-|01|21|37.262|3900000000}}

{{Infobox galaxy cluster

| name = Bullet Group

| image =

| caption =

| credit =

| epoch = J2000.0{{cite web |url= http://simbad.u-strasbg.fr/simbad/sim-id?submit=display&bibdisplay=refsum&bibyear1=1850&bibyear2=%24currentYear&Ident=%405354545&Name=SL2S+J08544-0121#lab_bib |title= [LCG2009] SL2S Group J08544-0121 -- Group of Galaxies |access-date= 18 July 2014 |publisher= SIMBAD }}

| constellation = Hydra

| ra = {{RA|08|54|46.5480}}

| dec = {{DEC|-01|21|37.262}}

| brightest_member =

| member_no =

| richness =

| bmtype =

| velocity_dispersion =

| redshift = 0.351

| distance =

| temperature =

| mass = {{val|2.4|0.6|e=14}}

| luminosity =

| flux =

| names = Bullet Group, SL2S J08544-0121

}}

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. The galaxies occur in two clumps, while the gas has expanded 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.{{cite journal |title= Dark matter-baryons separation at the lowest mass scale: the Bullet Group |display-authors= 6 |author= F. Gastaldello |author2= M. Limousin |author3= G. Foëx|author4= R. P. Muñoz |author5= T. Verdugo|author6= V. Motta |author7= A. More|author8= R. Cabanac |author9= D. A. Buote|author10= D. Eckert |author11= S. Ettori|author12= A. Fritz |author13= S. Ghizzardi|author14= P. J. Humphrey |author15= M. Meneghetti|author16= M. Rossetti |date= 22 Apr 2014 |publication-date= July 2014 |journal= Monthly Notices of the Royal Astronomical Society: Letters |volume= 442 |issue= 1 |page= L76–L80 |doi= 10.1093/mnrasl/slu058 |doi-access= free |bibcode= 2014MNRAS.442L..76G |arxiv= 1404.5633 }}{{cite web |url= http://sci.esa.int/xmm-newton/54116-cosmic-collision-in-the-bullet-group/ |title= Cosmic collision in the Bullet Group |date= 6 June 2014 |author= XMM-Newton |publisher= European Space Agency }} 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{{cite journal |title= A New Window of Exploration in the Mass Spectrum: Strong Lensing by Galaxy Groups in the SL2S |display-authors= 6 |author= M. Limousin |author2= R. Cabanac |author3= R. Gavazzi |author4= J.-P. Kneib |author5= V. Motta |author6= J. Richard |author7= K. Thanjavur |author8= G. Foex |author9= R. Pello |author10= D. Crampton |author11= C. Faure |author12= B. Fort |author13= E. Jullo |author14= P. Marshall |author15= Y. Mellier |author16= A. More |author17= G. Soucail |author18= S. Suyu |author19= M. Swinbank |author20= J.-F. Sygnet |author21= H. Tu |author22= D. Valls-Gabaud |author23= T. Verdugo|author24= J. Willis |date= 4 December 2008 |publication-date= August 2009 |journal= Astronomy and Astrophysics |volume= 502 |issue= 2 |pages= 445–456 |bibcode= 2009A&A...502..445L |doi= 10.1051/0004-6361/200811473 |arxiv= 0812.1033 |s2cid= 10168407 }}