Starship Asterisk*

The El Gordo Massive Galaxy Cluster

Explanation: It is bigger than a bread box. In fact, it is much bigger than all bread boxes put together. Galaxy cluster ACT-CL J0102-4915 is one of the largest and most massive objects known. Dubbed "El Gordo", the seven billion light years (z = 0.87) distant galaxy cluster spans about seven million light years and holds the mass of a million billion Suns. The above image of El Gordo is a composite of a visible light image from the Hubble Space Telescope, an X-ray image from the Chandra Observatory showing the hot gas in pink, and a computer generated map showing the most probable distribution of dark matter in blue, computed from gravitational lens distortions of background galaxies. Almost all of the bright spots are galaxies. The blue dark matter distribution indicates that the cluster is in the middle stages of a collision between two large galaxy clusters. A careful inspection of the image will reveal a nearly vertical galaxy that appears unusually long. That galaxy is actually far in the background and has its image stretched by the gravitational lens action of the massive cluster.

<< Previous APOD

This Day in APOD

Next APOD >>

[/b]

At seven million light years across, that's a lot of bull. Siriusly.

A long time ago in galaxies far, far away ...

I can confirm that the lens distortions through my little telescope also reveal a lot of darkness in this part of Phoenix. And I, too, would have to use a computer to make it appear blue. But I would have to stretch the truth, as well as the light curves, to call it dark matter.

With an angular size of ~9.5 arcmin, a bread box/bin 500m distant would appear about as big as El Gordo does in the southern sky.

Since it's 7,000,000,000+ LY away/ago, shouldn't all the verbs be past tense?
(Of course, anything we see is historical, but the vast distance means that everything is markedly different now.)

Guest wrote:Since it's 7,000,000,000+ LY away/ago, shouldn't all the verbs be past tense?
(Of course, anything we see is historical, but the vast distance means that everything is markedly different now.)

The light we are receiving for the cluster is the most up to date light we can get, though. Unless you're planning on actually traveling there or calculating the age of a distant galaxy it's not necessary to constantly think of everything beyond a few light seconds away as being in the past. What would be the cut off point for past tense consideration, anyhow?

Guest wrote:Since it's 7,000,000,000+ LY away/ago, shouldn't all the verbs be past tense?
(Of course, anything we see is historical, but the vast distance means that everything is markedly different now.)

Tenses are, were and always will be non-relativistic, unless noted otherwise.

Guest wrote:... the vast distance means that everything is markedly different now.

Very true. Many of the galaxies in this image will have merged by now, and other nearby galactic clusters should have been drawn toward this region too. Would it grow to the scale of our Great Attractor?

Bruce

The text says "hot gas in pink ..." But what are the brighter red "dots" ?
They seem to have an interesting distribution around El Gordo in this image.

My favorite part of this beautiful image (so far) is at the top center.
In the middle of a triangle of 3 of those red dots it looks like something wild is occurring.

they found Mr Hardy, now lets find Mr Laurel

ta152h0 wrote:they found Mr Hardy, now lets find Mr Laurel

Mr Laurel is in the center of the red portion of the mass, Long and stretched out with no other typical lensing hallmarks (arcs or foreground galaxy) apparent

geckzilla wrote:

Guest wrote:Since it's 7,000,000,000+ LY away/ago, shouldn't all the verbs be past tense?
(Of course, anything we see is historical, but the vast distance means that everything is markedly different now.)

The light we are receiving for the cluster is the most up to date light we can get, though. Unless you're planning on actually traveling there or calculating the age of a distant galaxy it's not necessary to constantly think of everything beyond a few light seconds away as being in the past. What would be the cut off point for past tense consideration, anyhow?

Good point considering the Sun we see in the sky is actually 8 1/2 light minutes older than what we view

Guest wrote:Since it's 7,000,000,000+ LY away/ago, shouldn't all the verbs be past tense?
(Of course, anything we see is historical, but the vast distance means that everything is markedly different now.)

If you're going to complain about that, you should also be aware that at z=0.87, the light travel time may be 7 billion light years, but the current distance is actually 10 billion light years. It's usually best not to overthink these things.

Are the red spots highly red-shifted distant galaxies or also hot gas depicted from the X-ray image from the Chandra Observatory? The colors are a curious adaption as we really can't see X-rays and we have to adjust them to a wavelength we can see. Is it also true of the blues of the dark matter versus the blues of the galaxy discs seen off center? I can't imagine it's also representational of the dark matter there too. Using color to illustrate un-seeable features can lead to a bit of confusion.

I wish I could think of an alternate strategy for composite images but it's rather akin to a two dimensional photo of a three dimension object; our current best portrayal of an "El-Gordian" truth.

Ron-Astro Pharmacist wrote:Are the red spots highly red-shifted distant galaxies or also hot gas depicted from the X-ray image from the Chandra Observatory? The colors are a curious adaption as we really can't see X-rays and we have to adjust them to a wavelength we can see. Is it also true of the blues of the dark matter versus the blues of the galaxy discs seen off center? I can't imagine it's also representational of the dark matter there too. Using color to illustrate un-seeable features can lead to a bit of confusion.

I wish I could think of an alternate strategy for composite images but it's rather akin to a two dimensional photo of a three dimension object; our current best portrayal of an "El-Gordian" truth.

Yes, it is very confusing to cram so much information into a single image composed solely of visible light. There's not a lot of room to put it all. The Chandra website uses a great technique to compensate for this by allowing users to isolate wavelengths to lessen the confusion a bit. Click the x-ray, optical, and mass links under the picture.
http://chandra.harvard.edu/photo/2014/elgordo/

Nitpicker wrote:With an angular size of ~9.5 arcmin, a bread box/bin 500m distant would appear about as big as El Gordo does in the southern sky.

Correction: The (interesting) Chandra website given in geckzilla's last post, lists the image scale as being about 5 arcmin across. My revised calculations give the angular size of El Gordo (and the breadbox at 500m) at ~3.5 arcmin. [PEBKAC.]

APOD Robot: wrote:Galaxy cluster ACT-CL J0102-4915 is one of the largest and most massive objects known. Dubbed "El Gordo", the seven billion light years (z = 0.87) distant galaxy cluster spans about seven million light years and holds the mass of a million billion Suns.

That being so, shouldn't this be called a Galatic Supercluster? Or had superclusters not yet formed at this universal age?

BDanielMayfield wrote:

APOD Robot: wrote:Galaxy cluster ACT-CL J0102-4915 is one of the largest and most massive objects known. Dubbed "El Gordo", the seven billion light years (z = 0.87) distant galaxy cluster spans about seven million light years and holds the mass of a million billion Suns.

That being so, shouldn't this be called a Galatic Supercluster? Or had superclusters not yet formed at this universal age?

El Gordo is not a supercluster, but superclusters had formed by this time (according to what I have just read).

The Wikipedia article: http://en.wikipedia.org/wiki/El_Gordo_(galaxy_cluster) says this:

As of 2014, it still holds the record for being the largest distant galaxy cluster to have been discovered.

(There's always a larger, more massive object, it seems.)

In the explanation it states "Dubbed "El Gordo", the seven billion light years (z = 0.87) distant galaxy cluster spans about seven million light years and holds the mass of a million billion Suns". Wow that's a lot of Suns!

With my very non-scientific mind I just cannot help wonder what effect (if any) a mass such as that of El Gordo has on the few billion light-years Universe that lie beyond it (from our perspective). As objects get ever nearer to the limit (is there one?) of the Universe then what happens at and after the limit may be way beyond mind-bogglingly awesome! What a let down therefore it will be if the Universe just ends abruptly (though probably still expanding at present) with nothing beyond!

DavidLeodis wrote:With my very non-scientific mind I just cannot help wonder what effect (if any) a mass such as that of El Gordo has on the few billion light-years Universe that lie beyond it (from our perspective). As objects get ever nearer to the limit (is there one?) of the Universe then what happens at and after the limit may be way beyond mind-bogglingly awesome! What a let down therefore it will be if the Universe just ends abruptly (though probably still expanding at present) with nothing beyond!

There is no limit to the Universe, there is no edge. From the position of this galaxy cluster, the Universe appears substantially similar to what we see. Every observer appears to be at the center of a local observable universe 93 billion light years across, or 27.6 billion light travel years across. From the viewpoint of the cluster, we appear to have a redshift of 0.87.

that is why an ice cold one on occasion is good for the mind. All the relative stuff makes humans be so puny. Salud, Universo !!!

Chris Peterson wrote:

DavidLeodis wrote:With my very non-scientific mind I just cannot help wonder what effect (if any) a mass such as that of El Gordo has on the few billion light-years Universe that lie beyond it (from our perspective). As objects get ever nearer to the limit (is there one?) of the Universe then what happens at and after the limit may be way beyond mind-bogglingly awesome! What a let down therefore it will be if the Universe just ends abruptly (though probably still expanding at present) with nothing beyond!

There is no limit to the Universe, there is no edge. From the position of this galaxy cluster, the Universe appears substantially similar to what we see. Every observer appears to be at the center of a local observable universe 93 billion light years across, or 27.6 billion light travel years across. From the viewpoint of the cluster, we appear to have a redshift of 0.87.

Thanks Chris.

I don't know about all of you but if you look real close at the center of the image there appears to be a face of some kind

What are the 3 diffuse reddish blobs in the upper half of the image?

ChrisHeinz wrote:What are the 3 diffuse reddish blobs in the upper half of the image?

I haven't been able to figure this out. There's only one compact x-ray source clearly associated with anything at all. I am giving this Twitter thing a try by tweeting to the Chandra team... maybe one of them will answer.