{{Short description|Largest distant galaxy cluster observed}} {{Galaxy cluster | name = El Gordo | image = 250px | caption = El Gordo consists of two separate galaxy sub-clusters colliding at several million<br>kilometres per hour. | credit = ESO/SOAR/NASA | constellation = Phoenix | epoch=J2000.0<ref name=SIMBAD/> | ra= {{RA|01|02|52.50}}<ref name=SIMBAD/> | dec={{DEC|-49|14|58.0}}<ref name=SIMBAD/> | member_no = | brightest_member = | richness = | redshift = 0.87<ref name=SIMBAD/> | temperature = | mass = | luminosity = | other_names = {{tooltip|El Gordo|The Fat One}},<ref name=SIMBAD/> {{nowrap|ACT-CL J0102-4915}},<ref name=NED/> {{nowrap|SPT-CL J0102-4915}}<ref name=NED/> }} thumb|This video shows the distant merging galaxy cluster ACT-CL J0102−4915. '''El Gordo''' (lit. ''The Fat One'') ('''ACT-CL J0102-4915''' or '''SPT-CL J0102-4915''') is the largest distant galaxy cluster observed at its distance or beyond, as of 2011. As of 2014, it held the record for being the largest distant galaxy cluster to have been discovered with a mass of slightly less than three quadrillion solar masses<ref>''Guinness World Records 2014'', Page 030.</ref><ref name="NASA-20140416">{{cite web |last1=Boen |first1=Brooke |last2=Dunbar |first2=Brian |title=Monster "El Gordo" Galaxy Cluster is Bigger Than Thought |url=http://www.nasa.gov/mission_pages/chandra/multimedia/elgordo-2014.html |date=16 April 2014 |work=NASA |access-date=17 April 2014 }}</ref><ref>NASA, [http://www.nasa.gov/mission_pages/chandra/multimedia/elgordo_photo.html "El Gordo Galaxy Cluster"] {{Webarchive|url=https://web.archive.org/web/20120113041204/http://www.nasa.gov/mission_pages/chandra/multimedia/elgordo_photo.html |date=2012-01-13 }}, 10 January 2012 (accessed 7 July 2012)</ref><ref>Monster NASA [http://www.nasa.gov/mission_pages/chandra/multimedia/elgordo-2014.html "Monster "El Gordo" Galaxy Cluster is Bigger Than Thought"]</ref> although later its mass was reduced to about {{val|2.1|e=15}} (2.1 quadrillion) solar masses with a 10% uncertainty.<ref name=Kim2021/> It was found by NASA's Chandra X-ray Observatory, the Atacama Cosmology Telescope (funded by the National Science Foundation) and the European Southern Observatory's Very Large Telescope.<ref>CNN News [http://lightyears.blogs.cnn.com/2012/01/10/fat-galaxy-discovered-7-billion-light-years-away/?hpt=hp_t3 'Fat' galaxy cluster discovered 7 billion light-years away] {{Webarchive|url=https://web.archive.org/web/20170816060424/http://lightyears.blogs.cnn.com/2012/01/10/fat-galaxy-discovered-7-billion-light-years-away/?hpt=hp_t3 |date=2017-08-16 }}</ref>
This galaxy cluster, officially named, 'ACT-CL J0102-4915', has been given the nickname 'El Gordo' (Spanish for "the Fat One") by researchers as an homage to the telescopes used for its discovery in the Atacama Desert in Northern Chile (ACT, VLT and SOAR). It is located more than 7 billion light-years from Earth.<ref>{{Cite web |url=http://www.nasa.gov/mission_pages/chandra/news/H-12-008.html |title=NASA's Chandra Finds Largest Galaxy Cluster in Early Universe |access-date=2012-01-11 |archive-date=2017-05-01 |archive-url=https://web.archive.org/web/20170501103010/https://www.nasa.gov/mission_pages/chandra/news/H-12-008.html |url-status=dead }}</ref>
Findings and results on 'El Gordo' were announced at the 219th meeting of American Astronomical Society in Austin, Texas.<ref>{{cite web |url=http://www.space.com/14192-largest-galaxy-cluster-el-gordo-photo-aas219.html |title=Monster Galaxy Cluster 'El Gordo' Packs Mass of 2 Quadrillion Suns |last=Choi |first=Charles |publisher=Space.com |date=January 10, 2012 |website=Space.com |access-date=April 13, 2017}}</ref>
==Observations== Findings from the European Southern Observatory's Very Large Telescope and the Chandra X-ray Observatory show that El Gordo is composed of two separate galaxy subclusters, colliding at several million kilometers per hour.<ref>CNN News [http://lightyears.blogs.cnn.com/2012/01/10/fat-galaxy-discovered-7-billion-light-years-away/?hpt=hp_t3 El Gordo is made up of two separate galaxy subclusters] {{Webarchive|url=https://web.archive.org/web/20170816060424/http://lightyears.blogs.cnn.com/2012/01/10/fat-galaxy-discovered-7-billion-light-years-away/?hpt=hp_t3 |date=2017-08-16 }}</ref> These observations (using X-ray data and other characteristics) suggest that El Gordo most probably formed in the same manner as the Bullet Cluster (which is located 4 billion light-years from Earth).<ref>{{cite web | url=https://www.sciencedaily.com/releases/2012/01/120110140423.htm | title=El Gordo: A 'fat' distant galaxy cluster }}</ref><ref>[http://chandra.si.edu/photo/2012/elgordo/ El Gordo akin to the well-known object called the Bullet Cluster]</ref><ref>[http://www.eso.org/public/news/eso1203/ El Gordo most probably formed just like the Blue Cluster]</ref><ref>{{Cite web |url=http://www.nasa.gov/mission_pages/chandra/news/H-12-008.html |title=El Gordo akin to the well-known object called the Bullet Cluster |access-date=2012-01-11 |archive-date=2017-05-01 |archive-url=https://web.archive.org/web/20170501103010/https://www.nasa.gov/mission_pages/chandra/news/H-12-008.html |url-status=dead }}</ref>
==El Gordo and ΛCDM== It was claimed that this interacting cluster presents problems for the conventional Lambda-CDM model of cosmology because it is hard to reconcile ΛCDM's model of galaxy formation with the combination of how early El Gordo is observed in cosmic history, its large mass, and its high collision velocity.<ref>{{cite journal |last1=Asencio |first1=Elena |last2=Banik |first2=Indranil |last3=Kroupa |first3=Pavel |title=A massive blow for ΛCDM – the high redshift, mass, and collision velocity of the interacting galaxy cluster El Gordo contradicts concordance cosmology |journal=Monthly Notices of the Royal Astronomical Society |date=February 2021 |volume=500 |issue=4 |pages=5249–5267 |doi=10.1093/mnras/staa3441 |doi-access=free |url=https://academic.oup.com/mnras/article/500/4/5249/5956544?guestAccessKey=82a69f32-f58f-4216-ac34-7f202334d24d |access-date=7 February 2021|arxiv=2012.03950 }}</ref> It was argued that later more accurate measurements have rejected this claim and led to a smaller mass estimate fully consistent with the ΛCDM cosmology.<ref name=Kim2021>{{Cite journal |last1=Kim |first1=Jinhyub |last2=Jee |first2=M. James |last3=Hughes |first3=John P. |last4=Yoon |first4=Mijin |last5=HyeongHan |first5=Kim |last6=Menanteau |first6=Felipe |last7=Sifón |first7=Cristóbal |last8=Hovey |first8=Luke |last9=Arunachalam |first9=Prasiddha |date=2021-12-01 |title=Head-to-Toe Measurement of El Gordo: Improved Analysis of the Galaxy Cluster ACT-CL J0102–4915 with New Wide-field Hubble Space Telescope Imaging Data |journal=The Astrophysical Journal |volume=923 |issue=1 |pages=101 |doi=10.3847/1538-4357/ac294f |issn=0004-637X|arxiv=2106.00031 |doi-access=free |bibcode=2021ApJ...923..101K }}</ref> However, the claims of consistency with ΛCDM were shown to be due to the assumption of a very low collision velocity that is not supported by any hydrodynamical simulations, not because of the slightly reduced mass estimate, which by itself does not solve the problem.<ref name=Asencio2023>{{cite journal |last1=Asencio |first1=Elena |last2=Banik |first2=Indranil |last3=Kroupa |first3=Pavel |title=The El Gordo galaxy cluster challenges ΛCDM for any plausible collision velocity |journal=The Astrophysical Journal |date=September 2023 | volume=954 |issue=2 |pages=162 |doi=10.3847/1538-4357/ace62a |issn=0004-637X|arxiv=2308.00744 |doi-access=free |bibcode=2023ApJ...954..162A }}</ref> According to Cristóbal Sifón from Pontifical Catholic University of Chile "this is the first time we've found a system like the Bullet Cluster at such a large distance."<ref>{{Cite web |title=Chandra finds largest galaxy cluster in early universe |url=https://phys.org/news/2012-01-chandra-largest-galaxy-cluster-early.html |access-date=2025-10-28 |website=phys.org |language=en}}</ref>
==Gallery== <gallery> File:A gargantuan collision ACT-CL J0102-4915.jpg|Galaxy cluster ACT-CL J0102-4915 contains the mass of about two million billion suns.<ref>{{cite web|title=A gargantuan collision|url=http://www.spacetelescope.org/images/potw1802a/|website=www.spacetelescope.org|access-date=8 January 2018}}</ref> File:Galaxy Cluster 'El Gordo' with Mass Map.jpg|Hubble image of ACT-CL J0102-4915<ref>{{cite news|title=Hubble weighs "the fat one"|url=http://www.spacetelescope.org/images/potw1414a/|access-date=10 April 2014|newspaper=ESA/Hubble Picture of the Week}}</ref> File:Webb spotlights gravitational arcs in ‘El Gordo’ galaxy cluster (NIRCam image) (elgordo1).jpg|JWST image of ACT-CL J0102-4915 </gallery>
==See also== * List of galaxy groups and clusters *RCS2 J2327, another galaxy cluster being the second-most-massive galaxy cluster at a record of two quadrillion, or two million billion, suns.
==References== <references> <ref name=SIMBAD>{{cite simbad |title= NAME El Gordo }}</ref> <ref name=NED>{{cite web |url= https://ned.ipac.caltech.edu/cgi-bin/objsearch?objname=ACT-CL+J0102-4915&extend=no&hconst=73&omegam=0.27&omegav=0.73&corr_z=1&out_csys=Equatorial&out_equinox=J2000.0&obj_sort=RA+or+Longitude&of=pre_text&zv_breaker=30000.0&list_limit=5&img_stamp=YES |title= SPT-CL J0102-4915 |publisher= NASA/IPAC Extragalactic Database }}</ref> </references>
==External links== * [https://web.archive.org/web/20120113041204/http://www.nasa.gov/mission_pages/chandra/multimedia/elgordo_photo.html El Gordo Galaxy Cluster] * [https://www.sciencedaily.com/releases/2012/01/120110140423.htm El Gordo: A 'Fat' Distant Galaxy Cluster] * [http://chandra.si.edu/photo/2012/elgordo/ El Gordo (ACT-CL J0102-4915): NASA's Chandra Finds Largest Galaxy Cluster in Early Universe] {{Phoenix (constellation)}}
{{DEFAULTSORT:El Gordo, Fat galaxy}} Category:Galaxy clusters Category:2012 in science Category:Phoenix (constellation) Category:Articles containing video clips