A 0.6 Mpc HI Structure Associated with Stephan's Quintet
Autor: | Xu, C. K., Cheng, C., Appleton, P. N., Duc, P. -A., Gao, Y., Tang, N. -Y., Yun, M., Dai, Y. S., Huang, J. -S., Lisenfeld, U., Renaud, F. |
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Rok vydání: | 2022 |
Předmět: | |
Druh dokumentu: | Working Paper |
Popis: | Stephan's Quintet (SQ, distance=85$\pm$6 Mpc) is unique among compact groups of galaxies. Observations have previously shown that interactions between multiple members, including a high-speed intruder galaxy currently colliding into the intragroup medium, have likely generated tidal debris in the form of multiple gaseous and stellar filaments, the formation of tidal dwarfs and intragroup-medium starbursts, as well as widespread intergalactic shocked gas. The details and timing of the interactions/collisions remain poorly understood because of the multiple nature. Here we report atomic hydrogen (HI) observations in the vicinity of SQ with a smoothed sensitivity of 1$\sigma$=4.2 $\times 10^{16}\rm cm^{-2}$ per channel ($\Delta$v=20 km s$^{-1}$; angular-resolution=4'), which are about two orders of magnitude deeper than previous observations. The data reveal a large HI structure (linear scale ~0.6 Mpc) encompassing an extended source of size ~0.4 Mpc associated with the debris field and a curved diffuse feature of length ~0.5 Mpc attached to the south edge of the extended source. The diffuse feature was likely produced by tidal interactions in early stages of SQ (>1 Gyr ago), though it is not clear how the low density HI gas (N$_{\rm HI}\leq 10^{18}\rm cm^{-2}$) can survive the ionization by the inter-galactic UV background on such a long time scale. Our observations require a rethinking of gas in outer parts of galaxy groups and demand complex modeling of different phases of the intragroup medium in simulations of group formation. Comment: 21 pages, 10 figures, accepted by Nature |
Databáze: | arXiv |
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