STScI: Monster El Gordo Galaxy Cluster

[orin stepanek]

http://hubblesite.org/news_release/news/2014-22/

Click to view full size image

ABOUT THIS IMAGE:

This is a Hubble Space Telescope image of the most massive cluster of galaxies ever seen to exist when the universe was just half of its current age of 13.8 billion years. The cluster, catalogued as ACT-CL J0102-4915, contains several hundred galaxies swarming around under the collective gravitational pull. The total mass of the cluster, as refined in new Hubble measurements, is estimated to weigh as much as 3 million billion stars like our Sun (about 3,000 times as massive as our own Milky Way galaxy) — though most of the mass is hidden away as dark matter. The location of the dark matter is mapped out in the blue overlay. Because dark matter doesn't emit any radiation, Hubble astronomers instead precisely measure how its gravity warps the images of far background galaxies like a funhouse mirror. This allowed them to come up with a mass estimate for the cluster. The cluster was nicknamed El Gordo (Spanish for "the fat one") in 2012 when X-ray observations and kinematic studies first suggested it was unusually massive for the time in the early universe when it existed. The Hubble data have confirmed that the cluster is undergoing a violent merger between two smaller clusters.

Object Names: El Gordo, ACT-CL J0102-4915

Image Type: Astronomical

Credit: NASA, ESA, and J. Jee (University of California, Davis)

N

[geckzilla]

Thankfully, they also included Milky Way units. I don't think Sun units express this mass very well.

[bystander]

CXC: Monster "El Gordo" Galaxy Cluster is Bigger than Thought

Weighing "El Gordo" with a Precision Scale: Hubble Space Telescope Weak-lensing
Analysis of the Merging Galaxy Cluster ACT-CL J0102-4915 at z=0.87 - M. James Jee et al

• Astrophysical Journal 785(1) 20 (2014 Apr 10) DOI: 10.1088/0004-637X/785/1/20
  arXiv.org > astro-ph > arXiv:1309.5097 > 19 Sep 2013 (v1), 22 Feb 2014 (v3)

[b][i]Image Credit: NASA, ESA, J. Jee (Univ. of California, Davis), J. Hughes (Rutgers Univ.), F. Menanteau (Rutgers Univ. & Univ. of Illinois, Urbana-Champaign), C. Sifon (Leiden Obs.), R. Mandelbum (Carnegie Mellon Univ.), L. Barrientos (Univ. Catolica de Chile), and K. Ng (Univ. of California, Davis)[/i][/b]

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[Ann]

The total mass of the cluster, as refined in new Hubble measurements, is estimated to weigh as much as 3 million billion stars like our Sun (about 3,000 times as massive as our own Milky Way galaxy) — though most of the mass is hidden away as dark matter.

Is that a lot? I find myself checking the colors and luminosities of galaxies using my software and the Principal Galaxy Catalog, and I think I come across massive galaxies all the time. Take the Virgo Cluster of galaxies. The PGC says that, for example, M88 is as luminous as 9.4 galaxies like the Milky Way. Assuming this is correct (which is may not be) it would "only" take about 300 galaxies like M88 to get the equivalent of 3,000 galaxies like the Milky Way. Of course that refers to luminosity and not to mass. But then let's look at M87. According to Wikipedia, M87 may contain 200 times as much mass as the Milky Way. Fifteen galaxies like M87 would be as massive as the El Gordo cluster, then.

Ann

[BDanielMayfield]

Is that a lot?

I'd say so, for this cluster's youthfulness Ann. By now, with another six and a half or so billion years to scarf down more of its surroundings, El Gordo must be truly muy grande ginormous.

Bruce