Galaxy harassment

Galaxy harassment is a form of galaxy interaction in which one or more galaxies interact with each frequently, or are influenced by external gravitational forces of a large galaxy cluster without a direct collision, usually in the form of a flyby.[1] The processes of galaxy harassment can change the morphology of the galaxy, including the triggering of starbursts or morphological changes in the galaxy's structure.[1][2] Galaxy harassment is different from galactic mergers, where galaxies directly collide and subsequently merge into a singular large galaxy,[2] leaving behind detectable streams of debris. These debris streams could also provide fuel for quasars in host galaxies.[3]

Effects

The mechanisms of galaxy harassment are not significant towards the outskirts of the galaxy cluster due to the smaller number of galaxies that exist. However, towards the center of the cluster, galaxy harassment becomes a significant process altering the morphology of a galaxy.[4] In fact, galaxy harassment drives the morphological evolution of galaxies in clusters.[3] Galaxies towards the outskirts of the galaxy cluster that experience harassment tend to loss only <6% of the total stellar mass while galaxies towards the center of the cluster can loss up to 50% of their total stellar mass. The inclination of a disk galaxy can reduce the mass loss of a galaxy, yet amplify the thickening of the galaxies disk.[5]

An example of the effects of galaxy harassment can be seen when comparing distant galaxy clusters past redshift distance z=0.4 to modern galaxy cluster we can see. Galaxy protoclusters at high distances are filled with small spiral galaxies showing signs of multiple phases of starburst activity but over time, galaxy harassment have transformed many of them into spheroidal galaxies.[6]

Globular clusters

Galaxy harassment can also affect the globular clusters (GCs) surrounding galaxies. They are strongly effected by the remaining dark matter left after a harassment. Only when dark matter around the galaxy falls to 15% do globular clusters start to get stripped and quickly separate from galaxies. When dark matter falls to just <3%, the galaxy is close to disruption.[7]

Examples

There are several examples of galaxies that have experienced galaxy harassment. One example is NGC 4254, also known as Messier 99. It is a spiral galaxy located in the Virgo cluster that is believed to have been harassed by another galaxy. This caused the galaxy to experience turbulence and alter the fine scale structure of the galaxies interstellar medium (ISM) suggesting that harassment effects more than just the morphology of the galaxy.[8]

Another example of a galaxy that was harassed is the Cartwheel galaxy, a lenticular galaxy with a noticeable ring around it, making it also a ring galaxy. Its features were formed from a high speed collision with another smaller galaxy transforming it from a Milky Way like galaxy to its current shape.[9][10]

See also

References

  1. ^ a b "Galaxy Harassment". supernova.lbl.gov. Retrieved 2025-04-23.
  2. ^ a b "Cosmological Evolution of Galaxies - Isaac Shlosman". ned.ipac.caltech.edu. Retrieved 2025-06-12.
  3. ^ a b Moore, Ben; Katz, Neal; Lake, George; Dressler, Alan; Oemler, Augustus (February 1996). "Galaxy harassment and the evolution of clusters of galaxies". Nature. 379 (6566): 613–616. arXiv:astro-ph/9510034. Bibcode:1996Natur.379..613M. doi:10.1038/379613a0. ISSN 1476-4687.
  4. ^ Bialas, D.; Lisker, T.; Olczak, C.; Spurzem, R.; Kotulla, R. (2015-04-01). "On the occurrence of galaxy harassment". Astronomy & Astrophysics. 576: A103. arXiv:1503.01965. Bibcode:2015A&A...576A.103B. doi:10.1051/0004-6361/201425235. ISSN 0004-6361.
  5. ^ Bialas, D.; Lisker, T.; Olczak, C.; Spurzem, R.; Kotulla, R. (2015-04-01). "On the occurrence of galaxy harassment". Astronomy & Astrophysics. 576: A103. arXiv:1503.01965. Bibcode:2015A&A...576A.103B. doi:10.1051/0004-6361/201425235. ISSN 0004-6361.
  6. ^ Moore, Ben; Lake, George; Katz, Neal (March 1998). "Morphological Transformation from Galaxy Harassment". The Astrophysical Journal. 495 (1): 139–151. arXiv:astro-ph/9701211. Bibcode:1998ApJ...495..139M. doi:10.1086/305264. ISSN 0004-637X.
  7. ^ Smith, R.; Sánchez-Janssen, R.; Fellhauer, M.; Puzia, T. H.; Aguerri, J. a. L.; Farias, J. P. (February 2013). "The impact of galaxy harassment on the globular cluster systems of early-type cluster dwarf galaxies". Monthly Notices of the Royal Astronomical Society. 429 (2): 1066–1079. arXiv:1211.2802. Bibcode:2013MNRAS.429.1066S. doi:10.1093/mnras/sts395. ISSN 0035-8711.
  8. ^ Dutta, Prasun; Begum, Ayesha; Bharadwaj, Somnath; Chengalur, Jayaram N. (2010-04-09), "Turbulence in the harassed galaxy NGC4254", Monthly Notices of the Royal Astronomical Society: Letters, 405 (1): L102–L106, arXiv:1004.1528, Bibcode:2010MNRAS.405L.102D, doi:10.1111/j.1745-3933.2010.00869.x
  9. ^ "Galaxy Harassment | COSMOS". astronomy.swin.edu.au. Retrieved 2025-06-12.
  10. ^ "New Image from NASA's James Webb Space Telescope Reveals Details of the Cartwheel Galaxy". kataeb.org. Retrieved 2025-06-12.
This article is issued from Wikipedia. The text is available under Creative Commons Attribution-Share Alike 4.0 unless otherwise noted. Additional terms may apply for the media files.