The Fornax Cluster is the nearest (≤20 Mpc) galaxy cluster in the southern sky. NGC?1404 is a bright elliptical galaxy falling through the intracluster medium (ICM) of the Fornax Cluster. The sharp leading edge of NGC 1404 forms a classical "cold front" that separates 0.6 keV dense interstellar medium and 1.5 keV diffuse ICM. We measure the angular pressure variation along the cold front using a very deep (670 ks) Chandra X-ray observation. We are taking the classical approach-using stagnation pressure to determine a substructure's speed-to the next level by not only deriving a general speed but also directionality, which yields the complete velocity field as well as the distance of the substructure directly from the pressure distribution. We find a hydrodynamic model consistent with the pressure jump along NGC 1404 s atmosphere measured in multiple directions. The best-fit model gives an inclination of 33° and a Mach number of 1.3 for the infall of NGC 1404, in agreement with complementary measurements of the motion of NGC 1404. Our study demonstrates the successful treatment of a highly ionized ICM as ideal fluid flow, in support of the hypothesis that magnetic pressure is not dynamically important over most of the virial region of galaxy clusters.
|State||Published - Jan 20 2017|
Bibliographical noteFunding Information:
This work was supported by Chandra Awards GO1-12160X and GO2-13125X issued by the Chandra X-ray Observatory Center, which is operated by the Smithsonian Astrophysical Observatory under NASA contract NAS8-03060.
© 2017. The American Astronomical Society. All rights reserved.
- X-rays: galaxies: clusters
- galaxies: clusters: intracluster medium
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science