CDG-2

CDG-2
Image of Candidate Dark Galaxy 2 (CDG-2) taken by Hubble Space Telescope, with the four globular clusters in it highlighted.
Observation data
ConstellationPerseus
Right ascension03h 17m 12.61s
Declination+41° 20′ 52.64″
Distancec. 245 million ly
Group or clusterPerseus
Notable featuresCandidate for a dark galaxy

Candidate Dark Galaxy 2 (CDG-2) is a candidate for a dark galaxy, composed predominantly of dark matter, along with four globular clusters, in the Perseus cluster.[1] It'd be one of the most dark matter dominated galaxies probably detected, estimated to be between 99.94% and 99.98% dark matter.[2] It has been not confirmed yet if it's a true dark galaxy, more studies are required for a definitive conclusion.

Discovery

CDG-2 was discovered by a Hubble Space Telescope survey (the PIPER survey) looking for larger than expected densities of globular clusters in the Perseus cluster. These higher densities of globular clusters could correspond to ultra-diffuse galaxies. In March 2025, researchers used a new statistical technique, a Poisson cluster process (adapted from the Neyman–Scott process), to perform the search and identified CDG-2 as a possible galaxy.[3] In June 2025 the Hubble Space Telescope images, images from the Euclid survey, and images from the Subaru telescope were examined[4] and diffuse emission around the globular clusters in CDG-2 was found, providing strong evidence that CDG-2 was indeed a galaxy. It is the first galaxy to be detected through the presence of globular clusters.[5]

Contents

Unlike most ultra-diffuse galaxies that have been discovered so far, CDG-2 is believed to only have the four globular clusters originally identified, though there were a few possible additional globular clusters that required further investigation. CDG-2 is estimated at having a dark matter halo mass of approximately , meaning that it is a highly dark matter dominated galaxy, with a halo mass fraction of 99.94 to 99.98%.[5] The existence of this galaxy may be a useful test for various theories of galaxy formation.[6] Since dark galaxies are a prediction of the Lambda-CDM model, the prevalence of dark galaxies is an important test of the theory, and simulations of their prevalence have drawn upon CDG-2 as a reference, along with Cloud-9.[7]

See also

References

  1. ^ "Dark Galaxy CDG-2 Near Perseus Cluster - NASA Science". 2026-02-18. Retrieved 2026-02-21.
  2. ^ Lea, Robert (2026-02-19). "Hubble telescope discovers rare galaxy that is 99% dark matter". Space. Retrieved 2026-02-21.
  3. ^ Li, Dayi; Stringer, Alex; Eadie, Gwendolyn; Abraham, Roberto (March 2025). "Poisson cluster process models for detecting ultra-diffuse galaxies". Annals of Applied Statistics. 19 (1): 261–285. doi:10.1214/24-AOAS1958 – via Project Euclid.
  4. ^ [email protected]. "Hubble identifies one of darkest known galaxies - The elusive object dubbed CDG-2 may be composed of 99% dark matter". www.esahubble.org. Retrieved 2026-02-21.
  5. ^ a b Li 李, Dayi (David) 大一; Liu 刘, Qing 青; Eadie, Gwendolyn M.; Abraham, Roberto G.; Marleau, Francine R.; Harris, William E.; van Dokkum, Pieter; Romanowsky, Aaron J.; Danieli, Shany; Brown, Patrick E.; Stringer, Alex (2025-06-16). "Candidate Dark Galaxy-2: Validation and Analysis of an Almost Dark Galaxy in the Perseus Cluster". The Astrophysical Journal Letters. 986 (2): L18. arXiv:2506.15644. Bibcode:2025ApJ...986L..18L. doi:10.3847/2041-8213/adddab. ISSN 2041-8205.
  6. ^ Garay, Jorge. "A Galaxy Composed Almost Entirely of Dark Matter Has Been Confirmed". Wired. ISSN 1059-1028. Retrieved 2026-02-21.
  7. ^ García-Bethencourt, Guacimara; Cintio, Arianna Di; Comerón, Sébastien; Arjona-Gálvez, Elena; Contreras-Santos, Ana; Cardona-Barrero, Salvador; Brook, Chris B. A.; Negri, Andrea; Libeskind, Noam I. (2026-01-07). "HI-bearing dark galaxies predictions from constrained Local Group simulations: how many and where to find them". arXiv:2601.04024 [astro-ph.GA].

Content Disclaimer

Informasi ini disarikan dari Wikipedia dan disajikan kembali untuk tujuan edukasi. Konten tersedia di bawah lisensi CC BY-SA 3.0. Kami tidak bertanggung jawab atas ketidakakuratan data yang bersumber dari kontribusi publik tersebut.

  1. The information displayed on this website is sourced in part or in whole from Wikipedia and has been adapted for the purpose of restating it. We strive to provide accurate and relevant information, however:
  2. There is no guarantee of absolute accuracy. Wikipedia is an open, collaborative project that can be edited by anyone, so information is subject to change.
  3. It is not intended to constitute professional advice. The content displayed is for informational and educational purposes only. For important decisions (e.g., medical, legal, or financial), please consult a professional.
  4. Content copyright. Wikipedia is licensed under the Creative Commons Attribution-ShareAlike License (CC BY-SA). This means that content may be reused with appropriate attribution and shared under a similar license.
  5. Responsible use. Any risk arising from the use of information from this website is entirely the responsibility of the user.