Supermassive black hole wake or bulgeless edge-on galaxy?
Abstract
A recent paper reported the serendipitous discovery of a thin linear object interpreted as the trail of star-forming regions left behind by a runaway supermassive black hole (SMBH) kicked out from the center of a galaxy. Despite the undeniable interest in the idea, the actual physical interpretation is not devoid of difficulty. The wake of a SMBH produces only small perturbations in the external medium, which has to be in exceptional physical conditions to collapse gravitationally and form a long (40 kpc) massive (3 × 109 M☉) stellar trace in only 39 Myr. Here we offer a more conventional explanation: the stellar trail is a bulgeless galaxy viewed edge-on. This interpretation is supported by the fact that its position-velocity curve resembles a rotation curve, which, together with its stellar mass, puts the object exactly on the Tully-Fisher relation characteristic of disk galaxies. Moreover, the rotation curve (Vmax ∼ 110 km s‒1), stellar mass, extension, width (z0 ∼ 1.2 kpc), and surface brightness profile of the object are very much like those of IC 5249, a well-known local bulgeless edge-on galaxy. These observational facts are difficult to interpret within the SMBH wake scenario. We discuss in detail the pros and cons of the two options.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- May 2023
- DOI:
- arXiv:
- arXiv:2304.12344
- Bibcode:
- 2023A&A...673L...9S
- Keywords:
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- Galaxy: halo;
- galaxies: individual: IC 5249;
- galaxies: kinematics and dynamics;
- galaxies: fundamental parameters;
- galaxies: peculiar;
- galaxies: structure;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- Accepted for publication in A&
