Astronomers are discovering an unusual galactic system with a long, highly parallel tail of gas and stars


Astronomers are discovering an unusual galactic system with a long, highly parallel tail of gas and stars

Galaxy Kite and its companion, Mrk 0926. Features along the tail are labeled a–j as shown. A candidate disruptive galaxy, Kite A, has also been classified. Image obtained from the Legacy Survey public archive and is in range 𝑔. The bar at the bottom right shows the length of 1 arcmin or the equivalent physical length over kite distance, 54 kpc. Credit: Zaritsky et al, 2023

An international team of astronomers has reported the discovery of a mysterious new galaxy system as part of the DESI Ancient Imaging Surveys. The newly discovered system consists of a pair of galaxies with an extremely extended tail of gas and stars. The result was reported on May 2nd arXiv Prepress server.

Galaxy tails may be a sign of a process or event that is transforming galaxies. Therefore, detecting and studying these features can help us better understand how galaxies form and evolve.

Now, a group of astronomers led by Dennis Zaritsky of the University of Arizona in Tucson, Arizona, has discovered an unusual new galactic tail with a variety of interesting features. Tail is associated with a binary galaxy system.

First, the researchers serendipitously discovered a new edge galaxy S0/a galaxy that has been given the designation PGC 1000273, while searching for low surface brightness (LSB) galaxies. Because of its formation, PGC 1000273 has been dubbed the “Kite” galaxy and observations find it lies about 610 million away. light years far.

Moreover, A.J companion galaxy to Kite has been identified about 186,000 light-years away. The companion, called PGC 070409, or Mrk 0926, is an active galaxy with a large scale. active galactic nucleus (AGN) at its center. Kite-Mrk 0926 has been found with a long galactic tail of gas and stars, which also hosts a small galaxy dubbed Kite A, which shows no evidence of continued star formation.

“We report the discovery of an unusual tail emanating from what we have dubbed the Paper Galaxy,” the researchers wrote in the paper.

The tail was found to have an expected length of about 1,240 light-years and an aspect ratio of 40. The images show that each of the emission nodes identified along the tail scatter at a site angle of less than 3°.

Therefore, the length, narrowness and linearity of the newly discovered tail make it an unusual example of a galactic tail. The kite tail is the longest optical galactic tail yet discovered. The only longer galactic structures are some of the radio-detected systems, which can reach lengths greater than 2,000 light-years.

What makes Kite Tail unusual is that it is rich in gas enough to support star formation along its length even though it originates from an S0/galaxy, which is expected to be gas-poor. Moreover, the tail is located in a low-density galactic environment with no group or cluster nearby but in a close binary galaxy system where both galaxies They are known to host AGNs.

Attempting to explain the origin of the detected extended tail, the paper’s authors concluded that the most plausible scenario was one in which a three-body encounter between the kite, Mrk 0926, and Kite A resulted in the rapid ejection of the smallest of them. galaxy.

The researchers concluded that “the tail resulted from a three-body interaction in which the least massive galaxy was ejected at high speed… The resulting hyperbolic orbit explains the linearity of the debris field and the narrowness of the tail.”

more information:
Denis Zaretsky et al., A long linear parallel galaxy tail 380 kbps fuzzy, arXiv (2023). doi: 10.48550/arxiv.2305.01335

Journal information:

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