2026年3月15日 (日) 12:19 imported>Kanshui0943

2026-03-15T12:19:02Z

新页面

{{Note TA
|1=zh-cn:项目;zh-tw:計畫
|G1=AS
}}
{{Infobox galaxy
|name=CDG-2
|image=CDG-2 Image from Hubble Space Telescope.jpg
|caption=哈勃太空望远镜拍摄的CDG-2图像，其中突显了该星系内的四个球状星团
|constellation name=[[英仙座]]
|ra={{RA|03|17|12.61}}|dec={{DEC|+41|20|52.64}}
|image_scale=
|dist_ly={{circa|2.45亿}}[[光年|ly]]
|group_cluster=[[英仙座星系團]]|references=https://science.nasa.gov/asset/hubble/dark-galaxy-cdg-2-near-perseus-cluster/|notes=为[[暗星系]]}}
'''候选暗星系2号'''（{{langx|en|Candidate Dark Galaxy 2}}，'''CDG-2'''）位于[[英仙座星系团]]，主要由[[暗物质]]构成，另有四个[[球状星团]]。<ref>{{Cite web |date=2026-02-18 |title=Dark Galaxy CDG-2 Near Perseus Cluster - NASA Science |url=https://science.nasa.gov/asset/hubble/dark-galaxy-cdg-2-near-perseus-cluster/ |access-date=2026-02-21 |language=en-US}}</ref>它是迄今发现暗物质占比最高的星系之一，估计暗物质逾99%。<ref>{{Cite web |last=Lea |first=Robert |date=2026-02-19 |title=Hubble telescope discovers rare galaxy that is 99% dark matter |url=https://www.space.com/astronomy/dark-universe/hubble-telescope-discovers-rare-galaxy-that-is-99-percent-dark-matter |access-date=2026-02-21 |website=Space |language=en}}</ref>
== 发现 ==
CDG-2由[[哈勃太空望远镜]]英仙座星系团巡天项目PIPER发现。该项目原为寻找[[球状星团]]密度异常偏高的区域，因为这类区域可能对应[[超稀疏星系]]。2025年3月，研究人员采用一种新统计方法，即[[泊松过程|泊松簇过程]]（由内曼—斯科特过程改造而来）展开搜寻，并将CDG-2识别为一颗可能存在的星系。<ref>{{Cite journal |last1=Li |first1=Dayi |last2=Stringer |first2=Alex |last3=Eadie |first3=Gwendolyn |last4=Abraham |first4=Roberto |date=March 2025 |title=Poisson cluster process models for detecting ultra-diffuse galaxies |url=https://projecteuclid.org/journals/annals-of-applied-statistics/volume-19/issue-1/Poisson-cluster-process-models-for-detecting-ultra-diffuse-galaxies/10.1214/24-AOAS1958.full |journal=Annals of Applied Statistics |volume=19 |issue=1 |pages=261–285 |doi=10.1214/24-AOAS1958 |via=Project Euclid|url-access=subscription }}</ref>2025年6月，研究人员检视哈勃太空望远镜、[[歐幾里得太空望遠鏡]]与[[昴星团望远镜]]图像后<ref>{{Cite web |last=information@eso.org |title=Hubble identifies one of darkest known galaxies - The elusive object dubbed CDG-2 may be composed of 99% dark matter |url=https://www.esahubble.org/news/heic2605/ |access-date=2026-02-21 |website=www.esahubble.org |language=en}}</ref>，在CDG-2球状星团周围发现弥散辐射，因而有力证明其为星系。它也是首个凭借球状星团踪迹发现的星系。<ref name=":0">{{Cite journal |last1=Li 李 |first1=Dayi (David) 大一 |last2=Liu 刘 |first2=Qing 青 |last3=Eadie |first3=Gwendolyn M. |last4=Abraham |first4=Roberto G. |last5=Marleau |first5=Francine R. |last6=Harris |first6=William E. |last7=van Dokkum |first7=Pieter |last8=Romanowsky |first8=Aaron J. |last9=Danieli |first9=Shany |last10=Brown |first10=Patrick E. |last11=Stringer |first11=Alex |date=2025-06-16 |title=Candidate Dark Galaxy-2: Validation and Analysis of an Almost Dark Galaxy in the Perseus Cluster |journal=The Astrophysical Journal Letters |volume=986 |issue=2 |pages=L18 |doi=10.3847/2041-8213/adddab |doi-access=free|arxiv=2506.15644 |bibcode=2025ApJ...986L..18L |issn=2041-8205}}</ref>

== 概述 ==
与迄今发现的大多数超弥漫星系不同，CDG-2据信只有最初识别出的四个球状星团，另有少数可能的球状星团仍待进一步查证。其[[暗物质晕]]质量估计约为<math>5.7 \times 10^{10} M_\odot</math>，可见这是一座暗物质占绝对优势的星系，晕质量占比达99.94%至99.98%。<ref name=":0" />这座星系的存在，或可成为检验多种星系形成理论的有力例证。<ref>{{Cite magazine |last=Garay |first=Jorge |title=A Galaxy Composed Almost Entirely of Dark Matter Has Been Confirmed |url=https://www.wired.com/story/a-galaxy-composed-almost-entirely-of-dark-matter-has-been-confirmed/ |access-date=2026-02-21 |magazine=Wired |language=en-US |issn=1059-1028}}</ref>暗星系是[[ΛCDM模型]]所预言的一类天体，其多寡因而成为检验这一理论的重要依据。相关丰度模拟也常以CDG-2和Cloud-9为参照。<ref>{{cite arXiv |last1=García-Bethencourt |first1=Guacimara |title=HI-bearing dark galaxies predictions from constrained Local Group simulations: how many and where to find them |date=2026-01-07 |eprint=2601.04024 |last2=Cintio |first2=Arianna Di |last3=Comerón |first3=Sébastien |last4=Arjona-Gálvez |first4=Elena |last5=Contreras-Santos |first5=Ana |last6=Cardona-Barrero |first6=Salvador |last7=Brook |first7=Chris B. A. |last8=Negri |first8=Andrea |last9=Libeskind |first9=Noam I. |class=astro-ph.GA }}</ref>

== 参考文献 ==
{{reflist|30em}}

{{暗物質}}
[[Category:星系]]
[[Category:暗星系]]
[[Category:暗物質]]
[[Category:哈伯太空望遠鏡影像]]
[[Category:天文学]]
[[Category:天体]]
[[Category:英仙座]]

CDG-2 - 版本历史

2026年3月15日 (日) 12:19 imported>Kanshui0943