View source for Abell 68

{{Short description|Galaxy cluster in the constellation Pisces}}
{{Infobox galaxy cluster|image=Hubble image of Abell 68 (8557242488).jpg|name=Abell 68|caption=The galaxy cluster, Abell 68 captured by the [[Hubble Space Telescope]] in 2012|constellation=[[Pisces (constellation)|Pisces]]|ra=00h 37m 05.300s|brightest_member=Abell 68 BCG (PGC 1360619)|epoch=[[J2000.0]]|dec=+09d 09m 11.00s|distance=3.668 [[light years|Gly]] (1124.6 [[Megaparsecs|Mpc]])|redshift=0.254600|names=NSCS J003706+090916, ZwCl 0034.4+0851, PSZ2 G116.95-53.55|luminosity=Between 6 × 1042 and 11 × 1044 [[erg]] s<sup>-1</sup>|richness=1|bmtype=Type I}}
'''Abell 68''' is massive and rich [[galaxy cluster]] located in the constellation of [[Pisces (constellation)|Pisces]] with a projected [[Comoving and proper distances|co-moving distance]] of approximately 1124.6 [[Parsec|Mpc]] or 3.668 billion light-years away from [[Earth]]. The cluster is especially notable for its [[gravitational lens]]ing<ref>{{Cite journal |last1=Yuan |first1=T. -T. |last2=Kewley |first2=L. J. |last3=Richard |first3=J. |date=2013-01-01 |title=The Metallicity Evolution of Star-forming Galaxies from Redshift 0 to 3: Combining Magnitude-limited Survey with Gravitational Lensing |url=https://ui.adsabs.harvard.edu/abs/2013ApJ...763....9Y |journal=The Astrophysical Journal |volume=763 |issue=1 |pages=9 |doi=10.1088/0004-637X/763/1/9 |arxiv=1211.6423 |bibcode=2013ApJ...763....9Y |issn=0004-637X}}</ref> and was first discovered by [[George O. Abell]] in 1958.<ref name=":0">{{Cite journal |last=Abell |first=George O. |date=1958-05-01 |title=The Distribution of Rich Clusters of Galaxies. |url=https://ui.adsabs.harvard.edu/abs/1958ApJS....3..211A |journal=The Astrophysical Journal Supplement Series |volume=3 |pages=211 |doi=10.1086/190036 |bibcode=1958ApJS....3..211A |issn=0067-0049}}</ref>
== History ==
Abell 68 is one of the original 2,712 [[Galaxy groups and clusters|galaxy clusters]] to be compiled inside the [[Abell catalogue|Abell Catalogue]] by George O. Abell who used the data that is retrieved from the [[National Geographic Society – Palomar Observatory Sky Survey|National Geographic Society - Palomar Observatory Sky Survey]].<ref name=":0" />
== Characteristics ==
Abell 68 has a [[temperature]] in the middle of 1-10 keV and a luminosity range of 6 × 10<sup>42</sup> to 11 × 10<sup>44</sup> erg s<sup>−1</sup>.<ref>{{Cite journal |last1=Molham |first1=Mona |last2=Clerc |first2=Nicolas |last3=Takey |first3=Ali |last4=Sadibekova |first4=Tatyana |last5=Morcos |first5=A. B. |last6=Yousef |first6=Shahinaz |last7=Hayman |first7=Z. M. |last8=Lieu |first8=Maggie |last9=Raychaudhury |first9=Somak |last10=Gaynullina |first10=Evelina R. |date=2020-05-01 |title=X-ray properties of the X-CLASS-redMaPPer galaxy cluster sample: the luminosity-temperature relation |journal=Monthly Notices of the Royal Astronomical Society |volume=494 |issue=1 |pages=161–177 |doi=10.1093/mnras/staa677 |doi-access=free |arxiv=2003.04624 |bibcode=2020MNRAS.494..161M |issn=0035-8711}}</ref>  Dynamically relaxed<ref>{{Cite journal |last1=Casas |first1=Madeline C. |last2=Putnam |first2=Ky |last3=Mantz |first3=Adam B. |last4=Allen |first4=Steven W. |last5=Somboonpanyakul |first5=Taweewat |date=2024-05-01 |title=Optical Photometric Indicators of Galaxy Cluster Relaxation |journal=The Astrophysical Journal |volume=967 |issue=1 |pages=14 |doi=10.3847/1538-4357/ad41de |doi-access=free |arxiv=2403.04897 |bibcode=2024ApJ...967...14C |issn=0004-637X}}</ref> but shows evidence of disturbed structures suggest the merger of a cluster.<ref>{{Cite journal |last1=Yuan |first1=Z. S. |last2=Han |first2=J. L. |last3=Wen |first3=Z. L. |date=2022-06-01 |title=Dynamical state of galaxy clusters evaluated from X-ray images |journal=Monthly Notices of the Royal Astronomical Society |volume=513 |issue=2 |pages=3013–3021 |doi=10.1093/mnras/stac1037 |doi-access=free |arxiv=2204.02699 |bibcode=2022MNRAS.513.3013Y |issn=0035-8711}}</ref> The galaxy cluster also has a massive size with an [[estimation]] of M<sub>500</sub> ≳ 2 × 10<sup>14</sup> M⊙. Several galaxies of Abell 68 are known to infall into the cluster as they pass through [[intergalactic gas]]. As they do so, the [[ram pressure]] takes place to strip the gas from galaxies with gas clouds heated in the process.<ref>{{Cite journal |last1=Koulouridis |first1=E. |last2=Gkini |first2=A. |last3=Drigga |first3=E. |date=2024-04-01 |title=AGNs in massive galaxy clusters: Role of galaxy merging, infalling groups, cluster mass, and dynamical state |url=https://ui.adsabs.harvard.edu/abs/2024A&A...684A.111K |journal=Astronomy and Astrophysics |volume=684 |pages=A111 |doi=10.1051/0004-6361/202348212 |arxiv=2401.05747 |bibcode=2024A&A...684A.111K |issn=0004-6361}}</ref><ref>{{Cite web |last=information@eso.org |title=Annotated Hubble image of Abell 68 |url=https://www.spacetelescope.org/images/heic1304b/ |access-date=2024-06-18 |website=www.spacetelescope.org |language=en}}</ref> Throughout the process, these galaxies classified as [[Jellyfish galaxy|jellyfish galaxies]], suffer the extinguishment of their star formations when AGN of the BCG in the cluster is switched on.<ref>{{Cite journal |last1=Maier |first1=C. |last2=Haines |first2=C. P. |last3=Ziegler |first3=B. L. |date=2022-02-01 |title=Star-formation quenching of cluster galaxies as traced by metallicity and presence of active galactic nuclei, and galactic conformity |url=https://ui.adsabs.harvard.edu/abs/2022A&A...658A.190M |journal=Astronomy and Astrophysics |volume=658 |pages=A190 |doi=10.1051/0004-6361/202141498 |arxiv=2110.02231 |bibcode=2022A&A...658A.190M |issn=0004-6361}}</ref>
Abell 68 is an accreting cluster with a clustercentric radius measuring r<sub>sp</sub>/r<sub>200,m</sub> = 1.291 ± 0.062 presenting a splashback feature<ref>{{Cite journal |last1=Bianconi |first1=Matteo |last2=Buscicchio |first2=Riccardo |last3=Smith |first3=Graham P. |last4=McGee |first4=Sean L. |last5=Haines |first5=Chris P. |last6=Finoguenov |first6=Alexis |last7=Babul |first7=Arif |date=2021-04-01 |title=LoCuSS: The Splashback Radius of Massive Galaxy Clusters and Its Dependence on Cluster Merger History |journal=The Astrophysical Journal |volume=911 |issue=2 |pages=136 |doi=10.3847/1538-4357/abebd7 |doi-access=free |arxiv=2010.05920 |bibcode=2021ApJ...911..136B |issn=0004-637X}}</ref> with a gas entropy showing the total feedback energy per [[particle]] declining from ~10 [[Electronvolt|keV]] to zero at ~0.35r<sub>200</sub> implying there is an [[Limit inferior and limit superior|upper limit]] of the feedback efficiency of ~0.02 for the [[supermassive black hole]] located in central region of the cluster's BCG.<ref>{{Cite journal |last1=Zhu |first1=Zhenghao |last2=Xu |first2=Haiguang |last3=Hu |first3=Dan |last4=Shan |first4=Chenxi |last5=Zhu |first5=Yongkai |last6=Fan |first6=Shida |last7=Zhao |first7=Yuanyuan |last8=Gu |first8=Liyi |last9=Wu |first9=Xiang-Ping |date=2021-02-01 |title=A Study of Gas Entropy Profiles of 47 Galaxy Clusters and Groups out to the Virial Radius |journal=The Astrophysical Journal |volume=908 |issue=1 |pages=17 |doi=10.3847/1538-4357/abd327 |doi-access=free |arxiv=2101.05947 |bibcode=2021ApJ...908...17Z |issn=0004-637X}}</ref>
According to researchers, Abell 68 has several [[Dwarf galaxy|dwarf galaxies]] members. Through investigating their [[Luminous efficiency function|luminosity function]] of (M<sub>i</sub> < -15), they found these galaxies located towards the end of the cluster exhibits a flat [[slope]] (α ~ -1.2 to -1.4) but at steeper profiles when being away from the cluster.<ref>{{Cite journal |last1=Hashimoto |first1=Yasuhiro |last2=Böhringer |first2=Hans |last3=Umetsu |first3=Keiichi |date=2022-04-01 |title=Dwarf galaxy luminosity functions and cluster environments |journal=Monthly Notices of the Royal Astronomical Society |volume=511 |issue=2 |pages=2796–2813 |doi=10.1093/mnras/stac209 |doi-access=free |bibcode=2022MNRAS.511.2796H |issn=0035-8711}}</ref>
== Gravitational lensed galaxies ==
[[File:Gravitational Lens Creates Cartoon of Space Invader.jpg|thumb|Gravitational lensing has caused the background galaxy to be split and stretched, hence giving this appearance.]]
Abell 68 has a strong [[gravitational lens]]. It was able to detect objects at a much further distance with the lens.<ref>{{Cite web |last=information@eso.org |title=Hubble image of Abell 68 |url=https://www.spacetelescope.org/images/heic1304a/ |access-date=2024-06-18 |website=www.spacetelescope.org |language=en}}</ref> According to observations by [[Hubble Space Telescope]], the gravitational lens was able to capture a background [[galaxy]], called ERO J003707.<ref name=":12">{{Cite journal |last1=Smith |first1=Graham P. |last2=Smail |first2=Ian |last3=Kneib |first3=J. -P. |last4=Davis |first4=C. J. |last5=Takamiya |first5=M. |last6=Ebeling |first6=H. |last7=Czoske |first7=O. |date=2002-06-01 |title=A Hubble Space Telescope lensing survey of X-ray luminous galaxy clusters - III. A multiply imaged extremely red galaxy at z=1.6 |journal=Monthly Notices of the Royal Astronomical Society |volume=333 |issue=1 |pages=L16–L20 |doi=10.1046/j.1365-8711.2002.05501.x |doi-access=free |arxiv=astro-ph/0203402 |bibcode=2002MNRAS.333L..16S |issn=0035-8711}}</ref> Located at redshift 1.6, the lens somehow twisted the galaxy into a form of a 1970s [[video game]] [[Extraterrestrial life|alien]] from [[Space Invaders]].<ref>{{Cite web |title=Gravitational Lens Creates Cartoon of Space Invader - NASA Science |url=https://science.nasa.gov/missions/hubble/gravitational-lens-creates-cartoon-of-space-invader/ |access-date=2024-06-18 |website=science.nasa.gov |language=en-US}}</ref> Furthermore ERO J003707, is an L* early-type [[Disc galaxy|disk galaxy]] with similar properties (R-K)>=5.3 and K<=21 shared by ~10 [[Percentage|percent]] of galaxies. Looking at its evolution stage, researchers theorized; the cooling of the gas presented by hierarchical [[Galaxy formation and evolution|galaxy formation]] models could develop EROJ003707 into a luminous [[spiral galaxy]].<ref name=":12" />
Researchers who presented [[Spitzer Space Telescope|Spitzer]] and [[Infrared Array Camera|IRAC]] surveys of H-faint (H 160 ≳ 26.4, < 5σ) sources in 101 lensing cluster fields, found more distant background [[Galaxy|galaxies]]. They are impressively large with median star populations M <sub>star</sub> = 10<sup>10.3±0.3</sup> M⊙, produced with [[star formation]] rates of = 100<sup>+60</sup><sub>-40</sub> M ⊙ yr<sup>−1</sup>. Not only to mention, they are obscured by dust that measures A <sub>V</sub> = 2.6 ± 0.3 and located at various redshifts of 3.9 ± 0.4. According to these researchers, they are confirmed to be H-faint galaxies making up at least 16<sup>+13</sup><sub>-7</sub>% of the galaxies but with a [[Stellar mass|stellar-mass]] range of 10<sup>10</sup> - 10<sup>11.2</sup> M ⊙ at z = 3 ~ 5. This gives rise to 8<sup>+8</sup><sub>-4</sub>% of the cosmic star formation rate [[density]] in the epoch showing the early phases of how massive galaxies were [[Galaxy formation and evolution|formed]].<ref>{{Cite journal |last1=Sun |first1=Fengwu |last2=Egami |first2=Eiichi |last3=Pérez-González |first3=Pablo G. |last4=Smail |first4=Ian |last5=Caputi |first5=Karina I. |last6=Bauer |first6=Franz E. |last7=Rawle |first7=Timothy D. |last8=Fujimoto |first8=Seiji |last9=Kohno |first9=Kotaro |last10=Dudzevičiūtė |first10=Ugnė |last11=Atek |first11=Hakim |last12=Bianconi |first12=Matteo |last13=Chapman |first13=Scott C. |last14=Combes |first14=Francoise |last15=Jauzac |first15=Mathilde |date=2021-12-01 |title=Extensive Lensing Survey of Optical and Near-infrared Dark Objects (El Sonido): HST H-faint Galaxies behind 101 Lensing Clusters |journal=The Astrophysical Journal |volume=922 |issue=2 |pages=114 |doi=10.3847/1538-4357/ac2578 |doi-access=free |arxiv=2109.01751 |bibcode=2021ApJ...922..114S |issn=0004-637X}}</ref>
== Abell 68 BCG ==
{{Infobox galaxy|name=Abell 68 Brightest Cluster Galaxy|constellation name=[[Pisces (constellation)|Pisces]]|epoch=[[J2000.0]]|ra=00h 37m 06.86s|dec=+09d 09m 23.6s|z=0.249403|h_radial_v=74,769 [[kilometer per second|km/s]]|dist_ly=3.651 [[light year|Gly]] (1119.4 [[Megaparsec|Mpc]])|group_cluster=Abell 68|appmag_v=0.257|appmag_b=0.340|sbrightness=26.5|type=[[Brightest Cluster Galaxy|BrCLG]]|names=[[2MASX]] J00370686+0909236, [[Principal Galaxies Catalogue|PGC]] 1360619, [[Sloan Digital Sky Survey|SDSS]] J003706.84+090924.1, WISEA J003706.85+090924.0|image=File:Black and white Hubble image of Abell 68 BCG.jpg|caption=Black and white [[Hubble]] image of Abell 68 BCG}}
The [[brightest cluster galaxy]] of Abell 68 or '''Abell 68 BCG''' (short for '''Abell 68 Brightest Cluster Galaxy'''), also known as '''PGC 1360619''', is a [[Type-cD galaxy|type-cD]] [[elliptical galaxy]]. It occupies as dominant member of the cluster. It is located in the constellation of [[Pisces (constellation)|Pisces]] with a [[redshift]] of 0.24.<ref>{{Cite web |title=Your NED Search Results |url=https://ned.ipac.caltech.edu/cgi-bin/objsearch?search_type=Obj_id&objid=2107909&objname=1&img_stamp=YES&hconst=73.0&omegam=0.27&omegav=0.73&corr_z=1 |access-date=2024-06-18 |website=ned.ipac.caltech.edu}}</ref>
Abell 68 BCG has a light profile. This [[surface brightness]] law, μ(''r'') ə ''r''<sup>1/4</sup>, described by de Vaucouleurs, has a large range in its [[radius]]<ref>{{Cite journal |last=de Vaucouleurs |first=Gerard |date=1948-01-01 |title=Recherches sur les Nebuleuses Extragalactiques |url=https://ui.adsabs.harvard.edu/abs/1948AnAp...11..247D |journal=Annales d'Astrophysique |volume=11 |pages=247 |bibcode=1948AnAp...11..247D |issn=0365-0499}}</ref> and fitted to the inner regions.<ref>{{Cite journal |last1=Kormendy |first1=John |last2=Djorgovski |first2=S. |date=1989-01-01 |title=Surface photometry and the structure of elliptical galaxies. |url=https://ui.adsabs.harvard.edu/abs/1989ARA&A..27..235K |journal=Annual Review of Astronomy and Astrophysics |volume=27 |pages=235–277 |doi=10.1146/annurev.aa.27.090189.001315 |bibcode=1989ARA&A..27..235K |issn=0066-4146}}</ref> It is an [[emission line]] galaxy with a strong [[Astronomical radio source|radio source]] and a powerful core component, in relationship with [O III] 5007 Å [[Line-emission spectrum|line emission]] when detected through [[Multi-frequency signaling|multifrequency]] radio [[observation]]s from [[Australia Telescope Compact Array]], Jansky [[Very Large Array]] and [[Very Long Baseline Array]] telescopes.<ref>{{Cite journal |last1=Hogan |first1=M. T. |last2=Edge |first2=A. C. |last3=Hlavacek-Larrondo |first3=J. |last4=Grainge |first4=K. J. B. |last5=Hamer |first5=S. L. |last6=Mahony |first6=E. K. |last7=Russell |first7=H. R. |last8=Fabian |first8=A. C. |last9=McNamara |first9=B. R. |last10=Wilman |first10=R. J. |date=2015-10-01 |title=A comprehensive study of the radio properties of brightest cluster galaxies |journal=Monthly Notices of the Royal Astronomical Society |volume=453 |issue=2 |pages=1201–1222 |doi=10.1093/mnras/stv1517 |doi-access=free |arxiv=1507.03019 |bibcode=2015MNRAS.453.1201H |issn=0035-8711}}</ref> Moreover, Abell 68 BCG is also a low-excitation [[radio galaxy]]. It has a 1.4 [[Hertz|GHz]] luminosity betwixt 2 × 10<sup>23</sup> and 3 × 10<sup>25</sup> W Hz<sup>−1</sup> caused by cooling gas  [[Accretion (astrophysics)|accretion]] from the hot [[atmosphere]], triggering the [[active galactic nucleus]] (AGN).<ref>{{Cite journal |last1=Lin |first1=Yen-Ting |last2=Huang |first2=Hung-Jin |last3=Chen |first3=Yen-Chi |date=2018-05-01 |title=An Analysis Framework for Understanding the Origin of Nuclear Activity in Low-power Radio Galaxies |journal=The Astronomical Journal |volume=155 |issue=5 |pages=188 |doi=10.3847/1538-3881/aab5b4 |doi-access=free |arxiv=1803.02482 |bibcode=2018AJ....155..188L |issn=0004-6256}}</ref> The galaxy is known to have a [[Infrared|near-infrared]] luminosity range of L<sub>X</sub> > 5 × 1044 [[erg]] s<sup>−1</sup>.<ref>{{Cite journal |last1=Stott |first1=J. P. |last2=Edge |first2=A. C. |last3=Smith |first3=G. P. |last4=Swinbank |first4=A. M. |last5=Ebeling |first5=H. |date=2008-03-01 |title=Near-infrared evolution of brightest cluster galaxies in the most X-ray luminous clusters since z = 1 |journal=Monthly Notices of the Royal Astronomical Society |volume=384 |issue=4 |pages=1502–1510 |doi=10.1111/j.1365-2966.2007.12807.x |doi-access=free |arxiv=0712.0496 |bibcode=2008MNRAS.384.1502S |issn=0035-8711}}</ref>
The galaxy is known to have a inactive appearance with a big [[velocity dispersion]] of σ > 160&nbsp;km s<sup>−1</sup> and much steeper as expected, when researchers created a velocity dispersion function of D<sub>n</sub>4000 > 1.5 within R<sub>200</sub>.<ref>{{Cite journal |last1=Sohn |first1=Jubee |last2=Geller |first2=Margaret J. |last3=Diaferio |first3=Antonaldo |last4=Rines |first4=Kenneth J. |date=2020-03-01 |title=Velocity Dispersions of Brightest Cluster Galaxies and Their Host Clusters |journal=The Astrophysical Journal |volume=891 |issue=2 |pages=129 |doi=10.3847/1538-4357/ab6e6a |doi-access=free |arxiv=1910.11192 |bibcode=2020ApJ...891..129S |issn=0004-637X}}</ref> Presumably, Abell 68 BCG was formed from [[galaxy merger]]s caused by [[Interacting galaxy|interacting]] smaller elliptical galaxies or spirals.<ref>{{Cite journal |last=Toomre |first=Alar |url=https://ui.adsabs.harvard.edu/abs/1977egsp.conf..401T |title=Mergers and Some Consequences |journal=Evolution of Galaxies and Stellar Populations |date=1977-01-01|page=401 |bibcode=1977egsp.conf..401T }}</ref> When collided together, process of [[dynamical friction]] is combined with mutual [[tidal force]]s. As [[kinetic energy]] is re-allotted into [[Random energy model|random energy]], these galaxies are then coalesced into an unshaped, triaxial system that becomes an elliptical galaxy like Abell 68 BCG.<ref>{{Cite journal |last=Hernquist |first=Lars |date=1993-06-01 |title=Structure of Merger Remnants. II. Progenitors with Rotating Bulges |url=https://ui.adsabs.harvard.edu/abs/1993ApJ...409..548H |journal=The Astrophysical Journal |volume=409 |pages=548 |doi=10.1086/172686 |bibcode=1993ApJ...409..548H |issn=0004-637X}}</ref><ref>{{Cite journal |last=Hernquist |first=Lars |date=1992-12-01 |title=Structure of Merger Remnants. I. Bulgeless Progenitors |url=https://ui.adsabs.harvard.edu/abs/1992ApJ...400..460H |journal=The Astrophysical Journal |volume=400 |pages=460 |doi=10.1086/172009 |bibcode=1992ApJ...400..460H |issn=0004-637X}}</ref>
== References ==
<references />
[[Category:Gravitational lensing]]
[[Category:Pisces (constellation)]]
[[Category:Abell objects]]
[[Category:Galaxy clusters]]
[[Category:Abell richness class 1]]