Bright dusty galaxies are hiding secret companions

Bright dusty galaxies are hiding secret companions
A portion of the region of the sky investigated by the paper, as seen by Herschel. This region is about 1.5 times the size of the full moon in the sky. Credit: JIllian Scudder

A new University of Sussex study has cleared the air on what lies behind hot dust visible in the distant universe.

Researchers found that the glow of heated dust reaching our planet is frequently due to three or four instead of a single one, as scientists had previously assumed.

The study, published in Monthly Notices of the Royal Astronomical Society, applied a statistical method to data from the Herschel Space Observatory to solve one of astrophysics' great conundrums.

Dr Jillian Scudder, lead author and Postdoctoral Research Fellow in Astrophysics, said: "This is a really interesting result because when we assumed that one galaxy had to be responsible for all of the dust emission, it implied that the galaxy must be forming a tremendous number of .

"Forming that number of stars in a galaxy so early in the Universe is quite hard to explain. By finding that each galaxy is actually two or three galaxies, we've dropped the number of stars these galaxies have to be producing by a third."

Far-infrared observations are relatively low resolution, and so each object detected by Herschel is blurred over an area about 26 times as large as the entire Milky Way. But if you look at the same patch of sky with better resolution, a number of galaxies appear, not just one.

This abundance of possible galaxies makes it difficult to figure out which of them is responsible for the dust glow. Historically, the galaxy closest to the centre of the dust glow is assigned responsibility for creating all of the light.

This new study used a to find the best possible way to split up the light seen by Herschel, given the positions of known . If one galaxy is found in the exact centre, it is probably responsible for most or all of the dust glow seen by Herschel. However, if there are no galaxies in the exact middle, or if the glow is not perfectly round, more than one galaxy is likely to be contributing to the light.

Dr. Scudder added: "Even after being revealed as multiple galaxies, each galaxy is still very bright, and forming a lot of new stars. The fact that there are several bright galaxies so close to each other on the sky may mean that they're interacting with each other, which might help explain how they got so bright in the first place."

The study looked at a sample of 360 objects detected at 250 micron by Herschel within the COSMOS field and revealed that the sample is almost entirely (95%) made up of at least two dust-bright galaxies hiding within the low-resolution images from Herschel.

"The multiplicity of 250-μm Herschel sources in the COSMOS field" has been accepted for publication in Monthly Notices of the Royal Astronomical Society.


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Image: The Stephan's Quintet of galaxies

More information: Jillian M. Scudder et al, The multiplicity of 250-μm sources in the COSMOS field, Monthly Notices of the Royal Astronomical Society (2016). DOI: 10.1093/mnras/stw1044 , http://arxiv.org/abs/1605.00006
Citation: Bright dusty galaxies are hiding secret companions (2016, May 6) retrieved 16 July 2019 from https://phys.org/news/2016-05-bright-dusty-galaxies-secret-companions.html
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May 06, 2016
Hi all. :)

I long ago recognized the problem now finally highlighted by mainstream astronomical researchers in above study. Last time I mentioned it was here in PO last month, in thread:

http://phys.org/n...nce.html

See my exchange with Phys1, IMP-9, Protoplasmix, especially from my post to Phys1 on March 09: I laid out why this problem seriously affects all prior 'interpretations' as to distance/type of 'object' actually 'imaged' using individual photons coming along 'line of sight' across near/intermediate/far distant reaches over long periods. This technique does not differentiate individual photos from: near low brightness objects/galaxies; or from intermnediate low brightness galaxies/clouds; or from far distant galaxies/intervening galaxy clusters.

Hence my caution: Far distant 'built-up images' are fraught with UN-knowns re intervening sources along line of sight (also from side-sourced photon paths 'bent' into that line of sight). :)

May 06, 2016
Hi all. :)


@ Really-Skippy. How you are Cher? I am pretty good, now, thanks for asking.

Far distant 'built-up images' are fraught with UN-knowns re intervening sources along line of sight (also from side-sourced photon paths 'bent' into that line of sight). :)
Maybe that is why Mrs-Ira-Skippette says the pictures I take are really bad, eh? Got any suggestions to make my picture taking better?

May 07, 2016
Hi Ira. :)

Got any suggestions to make my picture taking better?
Suggestion 1: Take the lens cap off first.

Or suggestion 2: Take your thumb away from the lens.

Or suggestion 3: Take the idiot away from behind the lens and give the camera to your Mrs.

Or all of above three suggestions at once would be best.

Now that the "funs" asides have been dispensed with, back to the on-topic and on-science discussion point made by me. Have you any intelligent contribution to make at all, or is the above inanity (and your bot-voting, of course) all that you are capable of? :)

May 07, 2016
Maybe that is why Mrs-Ira-Skippette says the pictures I take are really bad, eh? Got any suggestions to make my picture taking better?
@Uncle Ira
too subtle for him to grasp...

but hilarious!
thanks

May 07, 2016
"Big Bang" cosmology or Arp-Malek hypothesis of a dialectical universe?
http://redshift.v...2MAL.pdf
http://www.amazon...40414445

May 07, 2016
back to the on-topic and on-science discussion point made by me.
I was being on-topic and on-science trying to discuss the point made by you Cher.

Have you any intelligent contribution to make at all,
Non Cher, I already told you I was not the photographer. I am not contributing, I am hat-in-hand on this one and thanks for the advisement.

or is the above inanity (and your bot-voting, of course) all that you are capable of?
Non Cher, I am capable of a lot things, just not taking good pictures when stuffs are in the way like you said. But as far as the bot-voting thing, that is not so special, I got the computer set to do that for me without me even thinking about it. That was one of the best suggestions I got from you so far.

:)
And )"(,,)( right back to you podna.

May 07, 2016
The fact that there are several bright galaxies so close to each other on the sky may mean that they're interacting with each other, which might help explain how they got so bright in the first place.
Another possibility, of course, is that they're subject to the same environment and so they are all behaving much the same. Perhaps the JWST will be able to sort this out.

May 07, 2016
I long ago recognized the problem now finally highlighted by mainstream astronomical researchers in above study.


You did nothing of the sort. You claimed that the sky in the GOODS field would cause spurious objects. They are talking about extracting fluxes from confusion limited maps, GOODS is not confusion limited. The only thing you successfully demonstrated is that you don't understand photometry.

May 08, 2016
Hi IMP-9. :)

It's a class of problems in this area, not just the one. It involves the whole question of imaging from individual photons over long exposure times necessary to get any discernible 'image' build-up above background noise levels. It is this technique which in far-distant viewing is vulnerable to a whole array of spurious 'image' artifact/confusions possibilities because of the reasons I just mentioned above about UN-knowns for photon source/path contributions to the incident photons finally received here to build up an image which may have INnumerable sources/contributions OTHER than the assumed 'object' which a built-up image purports to represent. Look at the wider problem and the wider range of possible 'image' falsities/confusions which must then arise due to vast intervening sources between us far distant reaches of the universal space containing innumerable unknown LINE-OF-SIGHT photonic contributions to INDIVIDUAL PHOTON 'built-up image' techniques. :)

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