New Hubble image of a galaxy cluster

[Ann]

There is a new Hubble picture of a galaxy cluster. The aim of this new imaging of galaxy clusters is to see if they contain a particularly large amount of dark matter, and if giant galaxy clusters therefore may have begun assembling earlier than previously thought.

Read about it, and look at pictures, here.

Also check out this picture.

Looks to me as if the central galaxy must be really massive, in view of all the lensing that is happening becuase of it. Or else it isn't so much the central galaxy as it is all the dark matter in the cluster that is responsible for most of the lensing. Just look at that amazing wiggly-elongated lensed galaxy at 3 o'clock!

Ann

[Chris Peterson]

There is a new Hubble picture of a galaxy cluster. The aim of this new imaging of galaxy clusters is to see if they contain a particularly large amount of dark matter, and if giant galaxy clusters therefore may have begun assembling earlier than previously thought.

Wow, there's a lot of lensing going on there. Einstein is smiling.

One thing this and similar images are doing- and very effectively- is putting the final nails in the coffins of the various modified gravity theories. Dark matter is real, explains the structure of the Universe, and is an idea that is here to stay.

[bystander]

Hubble Survey Carries Out a Dark Matter Census
ESA/HEIC | spacetelescope.org | 2011 Oct 13

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The NASA/ESA Hubble Space Telescope has been used to make an image of galaxy cluster MACS J1206.2-0847. The apparently distorted shapes of distant galaxies in the background is caused by an invisible substance called dark matter, whose gravity bends and distorts their light rays. MACS 1206 has been observed as part of a new survey of galaxy clusters using Hubble.

Cluster MACS J1206.2-0847 (or MACS 1206 for short) is one of the first targets in a Hubble survey that will allow astronomers to construct the highly detailed dark matter maps of more galaxy clusters than ever before. These maps are being used to test previous but surprising results that suggest that dark matter is more densely packed inside clusters than some models predict. This might mean that galaxy cluster assembly began earlier than commonly thought.

The Cluster Lensing And Supernova survey with Hubble (CLASH) probes, with unparalleled precision, the distribution of dark matter in 25 massive clusters of galaxies. So far, the CLASH team has observed six of the 25 clusters.

Dark matter makes up the bulk of the Universe’s mass, yet it can only be detected by measuring how its gravity tugs on visible matter and warps the fabric of space-time like a fairground mirror so that the light from distant objects is distorted.

Galaxy clusters like MACS 1206 are perfect laboratories for studying dark matter’s gravitational effects because they are the most massive structures in the Universe to be held together by gravity. Because of their immense gravitational pull, the clusters act like giant cosmic lenses, amplifying, distorting and bending any light that passes through them — an effect known as gravitational lensing.

Lensing effects can also produce multiple images of the same distant object, as is evident in this Hubble picture. In particular, the apparent numbers and shapes of the distant galaxies far beyond a galaxy cluster become distorted as the light passes through, yielding a visible measurement of how much mass there is in the intervening cluster, and how it is distributed. The substantial lensing distortions seen are proof that the dominant mass component of the clusters is dark matter. The distortions would be far weaker if the clusters’ gravity came only from visible matter.

MACS 1206 lies four billion light-years from Earth. Hubble’s keen vision helped CLASH astronomers to uncover 47 multiple images of 12 newly identified faraway galaxies. Finding so many multiple images in a cluster is a unique capability of Hubble, and the CLASH survey is optimised to find them. The new observations build on earlier work by Hubble and ground-based telescopes.

Among the observations which complement Hubble’s is a major project using the European Southern Observatory’s Very Large Telescope. Unlike Hubble, which is making images of the clusters, the VLT is carrying out spectroscopic observations, where instruments split up the galaxies’ light into their component colours letting the scientists draw inferences about many of the properties of the cluster galaxies, including their distance and chemical makeup.

Taking advantage of two of Hubble’s powerful cameras, the Advanced Camera for Surveys and the Wide Field Camera 3, the CLASH survey covers a broad wavelength range, from ultraviolet to near-infrared.

Astronomers need the diverse colours to estimate the distances to the lensed galaxies and to study them in more detail. Hubble’s unique capabilities allow astronomers to estimate distances to galaxies that are four times fainter than those that ground-based telescopes can see.

The era when the first clusters formed is not precisely known, but is estimated to be at least nine billion years ago and possibly as far back as twelve billion years ago. If most of the clusters in the CLASH survey are found to have excessively high accumulations of dark matter in their central cores, then it may yield new clues about the early stages of the origin of structure in the Universe.

Future telescopes like the NASA/ESA/CSA James Webb Space Telescope (JWST), a space-based infrared observatory now being built, will be able to study the fainter lensed galaxies in clusters like MACS 1206 in greater detail. JWST will be powerful enough to observe the spectra of some of the magnified galaxies and study their early chemical composition.

Credit: NASA, ESA, M. Postman (STScI), the CLASH Survey Team, and the Hubble Heritage Team (STScI/AURA)

Zoomable Image

Ambitious Hubble Survey Obtaining New Dark Matter Census
NASA/STScI | HubbleSite | 2011 Oct 13

CLASH: Cluster Lensing And Supernova survey with Hubble

Hubble Heritage: Galaxy Cluster MACS J1206.2-0847

Gravitational Lens and Galaxy Cluster, MACS 1206

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Four and a half billion light years away in the constellation Virgo, scores of galaxies have been drawn together by the mutual pull of their gravity. NASA's Hubble Space Telescope peers through the depths of space and eons of light travel-time separating us and the galaxy cluster, known as MACS 1206, allowing scientists to study the distribution of mass in our universe at truly astronomical scales.

The eye is drawn toward the image's center: a glinting, glowering red pupil at the cluster's core. This central object is a giant elliptical galaxy plump with billions of old, reddish suns, surrounded by a thinner halo of stars. Moving outward, we find disk-shaped spiral galaxies in the image. Above and to the left of the center, two blue-white spiral galaxies pose face-on toward Hubble, both showing off a defined structure of arms encircling their central bulges.

These two main galaxy types, seen at different orientations and distances, occur again and again in this stunning Hubble image. Except for the lone diamond-spiked star in the bottom left, each and every extended bright object is a galaxy made up of roughly one hundred billion stars. The bluer galaxies have stars actively forming within them and, consequently, host groups of young blue stars that contribute to their overall hue. In contrast, red galaxies – especially those elliptical galaxies like the center one – are more stable in their behavior, with very few little recent star formation.

Though studded with striking objects, this isn't merely a hodgepodge of galaxies from cluster MACS 1206. This image has a radial symmetry around its center, creating a mesmeric effect that draws in the viewer. The circular pattern is evidence of an effect called gravitational lensing. Gravity from the cluster's immense mass bends the space around it, causing the images of more distant galaxies directly behind the cluster in our line of sight to be warped and cast into double images and arc-like smears of light. Perhaps the most obvious example of these optical distortions is the orange streak to the right of the image center.

Astronomers know that invisible "dark matter" vastly outweighs regular matter in clusters like MACS 1206, meaning that the luminous objects we see – all of the galaxies here – are surrounded by a much bigger cloud of dark matter. The bright galaxy at the heart of the lens lurks like a spider in the center of its web, a visible reminder of the unseen net of dark matter it rests in. Unwittingly, light from faraway galaxies flies through the cluster, only to become twisted up in the web of the cluster's lensing gravity.

Credit: NASA, ESA, M. Postman (STScI), the CLASH Survey Team, and the Hubble Heritage Team (STScI/AURA)

CLASH: New Multiple-Images Constraining the Inner Mass Profile of MACS J1206.2-0847 - A. Zitrin et al

• arXiv.org > astro-ph > arXiv:1107.2649 > 13 Jul 2011 (v1), 17 Jul 2011 (v2)

[orin stepanek]

ABOUT THIS IMAGE:

Click to view full size image

This image of galaxy cluster MACS J1206.2-0847 (or MACS 1206 for short) is part of a broad survey with NASA's Hubble Space Telescope.

The distorted shapes in the cluster are distant galaxies from which the light is bent by the gravitational pull of an invisible material called dark matter within the cluster of galaxies. This cluster is an early target in a survey that will allow astronomers to construct the most detailed dark matter maps of more galaxy clusters than ever before.

These maps are being used to test previous, but surprising, results that suggest that dark matter is more densely packed inside clusters than some models predict. This might mean that galaxy cluster assembly began earlier than commonly thought.

The multiwavelength survey, called the Cluster Lensing And Supernova survey with Hubble (CLASH), probes, with unparalleled precision, the distribution of dark matter in 25 massive clusters of galaxies. So far, the CLASH team has completed observations of six of the 25 clusters.

Dark matter makes up the bulk of the universe's mass, yet it can only be detected by measuring how its gravity tugs on visible matter and warps space like a fun-house mirror so that the light from distant objects is distorted.

Galaxy clusters like MACS 1206 are perfect laboratories for studying dark matter's gravitational effects because they are the most massive structures in the universe. Because of their heft, the clusters act like giant cosmic lenses, magnifying, distorting and bending any light that passes through them — an effect known as gravitational lensing.

Lensing effects can also produce multiple images of the same distant object, as evident in this Hubble picture. In particular, the apparent numbers and shapes of distant galaxies far beyond a galaxy cluster become distorted as the light passes through, yielding a visible measurement of how much mass is in the intervening cluster and how it is distributed. The substantial lensing distortions seen are proof that the dominant component of clusters is dark matter. The distortions would be far weaker if the clusters' gravity came only from the visible galaxies in the clusters.

MACS 1206 lies 4.5 billion light-years from Earth. Hubble's keen vision helped CLASH astronomers uncover 47 multiple images of 12 newly identified faraway galaxies. Finding so many multiple images in a cluster is a unique capability of Hubble, and the CLASH survey is optimized to find them. The new observations build on earlier work by Hubble and ground-based telescopes.

Taking advantage of two of Hubble's powerful cameras, the Advanced Camera for Surveys and the Wide Field Camera 3, the CLASH survey covers a broad wavelength range, from ultraviolet to near infrared. Astronomers need the diverse colors to estimate the distances to lensed galaxies and study them in more detail. Hubble's unique capabilities allow astronomers to estimate distances to galaxies that are four times fainter than ground-based telescopes can see.

The era when the first clusters formed is not precisely known, but is estimated to be at least 9 billion years ago and possibly as far back as 12 billion years ago. If most of the clusters in the CLASH survey are found to have excessively high accumulations of dark matter in their central cores, then it may yield new clues to the early stages in the origin of structure in the universe.

Future telescopes like NASA's James Webb Space Telescope, a space-based infrared observatory now being built, will be able to study the fainter lensed galaxies in clusters like MACS 1206 in greater detail. Webb will be powerful enough to collect the spectra of some of the magnified galaxies to study their early chemical composition.

For additional information, contact:

Donna Weaver / Ray Villard
Space Telescope Science Institute, Baltimore, Md.
410-338-4493 / 410-338-4514
dweaver@stsci.edu / villard@stsci.edu

Marc Postman
Space Telescope Science Institute, Baltimore, Md.
410-338-4340
postman@stsci.edu

Object Name: MACS J1206.2-0847

Image Type: Astronomical


Credit: NASA, ESA, M. Postman (STScI), and the CLASH Team

[Beyond]

Orin, when i first saw that picture, i thought, where did that giant orange space worm come from. Then i realized that it was a lensing effect, and actually covers quite a big area. heh-heh, good thing it's not actually a space worm. I'd hate to see the size of the fish or bird that would be going after it

[BMAONE23]

The central Elliptical Galaxy looks like it might have an unseen companion lying almost directly behind it. If this is the case it would also add to the mass of the gravity lens