The recent growth history of the Fornax Cluster derived from simultaneous sloshing and gas stripping: Simulating the infall of NGC 1404

Sheardown, Alex; Roediger, Elke; Su, Yuanyuan; Kraft, Ralph P.; Fish, Thomas; ZuHone, John A.; Forman, William R.; Jones, Christine; Churazov, Eugene; Nulsen, Paul E.J.

Abstract

We derive the recent growth history of the Fornax Cluster, in particular the recent infall of the giant elliptical galaxy NGC 1404. We show, using a simple cluster minor merger simulation tailored to Fornax and NGC 1404, that a second or more likely third encounter between the two reproduces all the main merger features observed in both objects; we firmly exclude a first infall scenario. Our simulations reveal a consistent picture: NGC 1404 passed by NGC 1399 about 1.1–1.3 Gyr ago from the northeast to the southwest and is now almost at the point of its next encounter from the south. This scenario explains the sloshing patterns observed in Fornax—a prominent northern cold front and an inner southern cold front. This scenario also explains the truncated atmosphere, the gas-stripping radius of NGC 1404, and its faint gas tail. Independent of the exact history, we can make a number of predictions. A detached bow shock south of NGC 1404 should exist, which is a remnant of the galaxy's previous infall at a distance from NGC 1404 between 450 and 750 kpc with an estimated Mach number between 1.3 and 1.5. The wake of NGC 1404 also lies south of the galaxy with enhanced turbulence and a slight enhancement in metallicity compared to the undisturbed regions of the cluster. Southwest of NGC 1404, there is likely evidence of old turbulence originating from the previous infall. No scenario predicts enhanced turbulence outside of the cold front northwest of the cluster center.

Citation

Sheardown, A., Roediger, E., Su, Y., Kraft, R. P., Fish, T., ZuHone, J. A., Forman, W. R., Jones, C., Churazov, E., & Nulsen, P. E. (2018). The recent growth history of the Fornax Cluster derived from simultaneous sloshing and gas stripping: Simulating the infall of NGC 1404. The Astrophysical journal, 865(2), 118. https://doi.org/10.3847/1538-4357/aadc0f

• Journal Article Type: Article
• Acceptance Date: Aug 19, 2018
• Online Publication Date: Sep 28, 2018
• Publication Date: Oct 1, 2018
• Deposit Date: Oct 12, 2018
• Publicly Available Date: Oct 15, 2018
• Journal: The Astrophysical Journal
• Print ISSN: 0004-637X
• Publisher: American Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 865
• Issue: 2
• Article Number: 118
• Pages: 118
• DOI: https://doi.org/10.3847/1538-4357/aadc0f
• Keywords: Space and Planetary Science; Astronomy and Astrophysics
• Public URL: https://hull-repository.worktribe.com/output/1115147
• Publisher URL: http://iopscience.iop.org/article/10.3847/1538-4357/aadc0f/meta
• Additional Information: Journal title: The Astrophysical Journal; Article type: paper; Article title: The Recent Growth History of the Fornax Cluster Derived from Simultaneous Sloshing and Gas Stripping: Simulating the Infall of NGC 1404; Copyright information: © 2018. The American Astronomical Society. All rights reserved.; Date received: 2018-05-18; Date accepted: 2018-08-19; Online publication date: 2018-09-28
• Contract Date: Oct 15, 2018