3 years ago

Snapshots of structure formation of a Cosmic Beast: Full-scale observations and simulations of MACS J0717.5+3745.

A. Robertson, E. Medezinski, K. Umetsu, S. T. Kay, R. Massey, M. Nonino, Y. Bahé, D. Eckert, C. Dalla Vecchia, E. Jullo, D. Barnes, D. Harvey, J. Schwinn, M. Schaller, S. I. Tam, P. Natarajan, J.-P. Kneib, H. Ebeling, M. Jauzac, C. Baugh, M. Limousin

We present a gravitational lensing and X-ray analysis of a massive galaxy cluster and its surroundings. The core of MACS\,J0717.5+3745 ($M(R<1\,{\rm Mpc})\sim$\,$2$\times$10^{15}\,\msun$, $z$=$0.54$) is already known to contain four merging components. We show that this is surrounded by at least seven additional substructures with masses ranging from $3.8-6.5\times10^{13}\,\msun$, at projected radii $1.6$ to $4.9$\,Mpc. We compare MACS\,J0717 to mock lensing and X-ray observations of similarly rich clusters in cosmological simulations. The low gas fraction of substructures predicted by simulations turns out to match our observed values of $1$--$4\%$. The typical growth rate and substructure infall velocity of simulated clusters suggests that MACS\,J0717 will evolve into a system similar to, but more massive than, Abell~2744 by $z=0.31$, and into a $\sim$\,$10^{16}\,\msun$ supercluster by $z=0$. The radial distribution of infalling substructure suggests that merger events are strongly episodic; however we find that the smooth accretion of surrounding material remains the main source of mass growth even for such massive clusters.

Publisher URL: http://arxiv.org/abs/1711.01324

DOI: arXiv:1711.01324v1

You might also like
Never Miss Important Research

Researcher is an app designed by academics, for academics. Create a personalised feed in two minutes.
Choose from over 15,000 academics journals covering ten research areas then let Researcher deliver you papers tailored to your interests each day.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.