The Cheshire Cat Gravitational Lens: The Formation of a Massive Fossil Group
|Irwin, Jimmy A.
|Carrasco, Eleazar R.
|Maksym, W. Peter
|White, Raymond E. III
|University of Alabama Tuscaloosa
|The Cheshire Cat is a relatively poor group of galaxies dominated by two luminous elliptical galaxies surrounded by at least four arcs from gravitationally lensed background galaxies that give the system a humorous appearance. Our combined optical/X-ray study of this system reveals that it is experiencing a line of sight merger between two groups with a roughly equal mass ratio with a relative velocity of ∼1350 km s−1 . One group was most likely a lowmass fossil group, while the other group would have almost fit the classical definition of a fossil group. The collision manifests itself in a bimodal galaxy velocity distribution, an elevated central X-ray temperature and luminosity indicative of a shock, and gravitational arc centers that do not coincide with either large elliptical galaxy. One of the luminous elliptical galaxies has a double nucleus embedded off-center in the stellar halo. The luminous ellipticals should merge in less than a Gyr, after which observers will see a massive 1.2–1.5 × 1014 M⊙ fossil group with an Mr = −24.0 brightest group galaxy at its center. Thus, the Cheshire Cat offers us the first opportunity to study a fossil group progenitor. We discuss the limitations of the classical definition of a fossil group in terms of magnitude gaps between the member galaxies. We also suggest that if the merging of fossil (or nearfossil) groups is a common avenue for creating present-day fossil groups, the time lag between the final galactic merging of the system and the onset of cooling in the shock-heated core could account for the observed lack of well-developed cool cores in some fossil groups.
|Irwin, J., et al. (2015): The Cheshire Cat Gravitational Lens: The Formation of a Massive Fossil Group. The Astrophysical Journal, 806(2).
|galaxies: clusters: individual (SDSS J1038+4849)
|gravitational lensing: strong
|X-rays: galaxies: clusters
|The Cheshire Cat Gravitational Lens: The Formation of a Massive Fossil Group
1 - 1 of 1
- JIrwin_The Cheshire Cat Gravitational Lens_Physics and Astronomy.pdf
- 1003.09 KB
- Adobe Portable Document Format
- main article
1 - 1 of 1
No Thumbnail Available
- 1.27 KB
- Item-specific license agreed upon to submission