The Arecibo Galaxy Environment Survey. XII. Optically Dark HI Clouds in the Leo I Group

0565100 - ASÚ 2023 RIV US eng J - Journal Article
Taylor, Rhys - Köppen, J. - Jáchym, Pavel - Minchin, R. - Palouš, Jan - Rosenberg, J. L. - Schneider, S. - Wünsch, Richard - Deshev, Boris
The Arecibo Galaxy Environment Survey. XII. Optically Dark HI Clouds in the Leo I Group.
Astronomical Journal. Roč. 164, č. 6 (2022), č. článku 233. ISSN 0004-6256. E-ISSN 1538-3881
R&D Projects: GA MŠMT(CZ) LM2015067; GA ČR(CZ) GA19-18647S
Institutional support: RVO:67985815
Keywords : fast alpha survey * virgo cluster * tidal debris
OECD category: Astronomy (including astrophysics,space science)
Impact factor: 5.3, year: 2022
Method of publishing: Open access

Using data from the Arecibo Galaxy Environment Survey, we report the discovery of five H I clouds in the Leo I group without detected optical counterparts. Three of the clouds are found midway between M96 and M95, one is only 10' from the southeast side of the well-known Leo Ring, and the fifth is relatively isolated. H I masses range from 2.6 x 10(6) M-circle dot to 9.0 x 10(6) M-circle dot, and velocity widths (W50) range from 16 to 42 km s(-1). Although a tidal origin is the most obvious explanation, this formation mechanism faces several challenges. For the most isolated cloud, the difficulties are its distance from neighboring galaxies and the lack of any signs of disturbance in the H I disks of those systems. Some of the clouds also appear to follow the baryonic Tully-Fisher relation between mass and velocity width for normal, stable galaxies, which is not expected if they are tidal in origin. Three clouds are found between M96 and M95 that have no optical counterparts but have otherwise similar properties and locations to the optically detected galaxy LeG 13. While overall we favor a tidal debris scenario to explain the clouds, we cannot rule out a primordial origin. If the clouds were produced in the same event that gave rise to the Leo Ring, they may provide important constraints on any model attempting to explain that structure.
Permanent Link: https://hdl.handle.net/11104/0338032