The diversity of distant galaxies

Jun 10, 2013
A field of distant galaxies as seen at long infrared wavelengths over a region about one-third the size of the moon. The poor spatial resolution of infrared telescopes coupled with the great distances of the galaxies preclude seeing their spiral (or other) structures, but their different colors are apparent. A new study of 2500 distant infrared galaxies concludes they are more varied than local galaxies, probably due to different kinds of dust and dusty conditions in these early objects. Credit: ESA GOOD-S

(Phys.org) —With the advent of powerful space infrared telescopes like the Spitzer Space Telescope and the (recently deceased) Herschel Space Telescope, astronomers have been able to study the properties of dust in galaxies so remote that their light has been traveling towards us for over ninety percent of the age of the universe. That these distant objects are detected at all is because they are very bright in the infrared, and they are bright because they are making huge numbers of stars whose light warms the dust that in turn radiates at infrared wavelengths.

Local galaxies - those only hundreds of millions of light-years away in our cosmic neighborhood - provide a template for understanding how galaxies behave, and are the basis for models of their distant cousins. It has been known for decades that the early universe was actively making stars in galaxies. A key question for astronomers is whether distant galaxies are different enough from local ones that different physical processes need to be included in the models, or whether comparisons with local objects are valid.

CfA astronomer Ho Seong Hwang and a large team of his collaborators have analyzed a large sample of distant galaxies to address this question. The Herschel Space Telescope during its lifetime observed many distant . The astronomers selected 2500 of them from a set of over fifty thousand, based on their having clear detections at several with ancillary data from other missions. The sample was selected in a way that was independent of observer preferences, like extreme brightness, that might compromise the conclusions, the first time this has been done for such a large sample.

The results were surprising. The scientists found that the dust in remote tended to be warmer than it is in local galaxies of the same luminosity. Together with other indicators, the data suggest that the character of the dust and its environments have evolved with time in ways that are still not well known. Probably as a result of the dust variations there also appears to be a greater diversity of types of galaxies in the early universe. Finally, the new paper notes, in accord with other recent papers, that there are indications that these galaxies may have started forming sooner after the big bang than had been anticipated in some old models.

Explore further: POLARBEAR detects curls in the universe's oldest light

Related Stories

The distant cosmos as seen in the infrared

Apr 12, 2013

(Phys.org) —At some stage after its birth in the big bang, the universe began to make galaxies. No one knows exactly when, or how, this occurred. For that matter, astronomers do not know how the lineages ...

Mysterious red galaxies

Dec 12, 2011

(PhysOrg.com) -- Perhaps the most astonishing and revolutionary discovery in cosmology was Edwin Hubble's observation that galaxies are moving away from us with velocities that are proportional to their distances. ...

Galaxies the way they were

Apr 03, 2013

(Phys.org) —Galaxies today come very roughly in two types: reddish, elliptically shaped collections of older stars, and bluer, spiral shaped objects dominated by young stars. The conventional wisdom is ...

Modeling galaxy mergers

Jun 03, 2013

(Phys.org) —Astronomers think that many galaxies, including our own Milky Way, have undergone similar collisions during their lifetimes. Although galaxy collisions are important and common, what happens ...

Recommended for you

Big black holes can block new stars

15 hours ago

Massive black holes spewing out radio-frequency-emitting particles at near-light speed can block formation of new stars in aging galaxies, a study has found.

POLARBEAR seeks cosmic answers in microwave polarization

16 hours ago

An international team of physicists has measured a subtle characteristic in the polarization of the cosmic microwave background radiation that will allow them to map the large-scale structure of the universe, ...

New radio telescope ready to probe

19 hours ago

Whirring back and forth on a turning turret, the white, 40-foot dish evokes the aura of movies such as "Golden Eye" or "Contact," but the University of Arizona team of scientists and engineers that commissioned ...

Exomoons Could Be Abundant Sources Of Habitability

Oct 20, 2014

With about 4,000 planet candidates from the Kepler Space Telescope data to analyze so far, astronomers are busy trying to figure out questions about habitability. What size planet could host life? How far ...

Partial solar eclipse over the U.S. on Thursday, Oct. 23

Oct 17, 2014

People in most of the continental United States will be in the shadow of the Moon on Thursday afternoon, Oct. 23, as a partial solar eclipse sweeps across the Earth. For people looking through sun-safe filters, from Los Angeles, ...

User comments : 6

Adjust slider to filter visible comments by rank

Display comments: newest first

visualhawk
2.3 / 5 (3) Jun 10, 2013
"That these distant objects are detected at all is because they are very bright in the infrared, and they are bright because they are making huge numbers of stars whose light warms the dust that in turn radiates at infrared wavelengths"

No really - these galaxies are so far away that they move at a fair percentage of c causing their light to red-shift into the IR frequencies. The reason why they are building the James Webb telescope. Some of it may be due to the heating of dust but that is not the main reason why they are only observable in IR
Fleetfoot
5 / 5 (1) Jun 10, 2013
The results were surprising. The scientists found that the dust in remote luminous galaxies tended to be warmer than it is in local galaxies of the same luminosity.


With a link to:

Explore further: Herschel bows out with study that shows early galaxies 'cooler' than predicted


From the article, this new study seems to be looking at higher red shift galaxies than the previous one implying the evolution is quite complex.
philw1776
1 / 5 (1) Jun 10, 2013
I've not read that the density of galaxy clusters at high redshift is markedly higher than our local few billion LYs. My question is moot if the observed density is high. But if the galactic cluster density is not considerably higher, shouldn't it be as space has been expanding since the BB? If so what does standard BB cosmology have to say about this?
Greenwood
5 / 5 (3) Jun 10, 2013
"these galaxies are so far away that they move at a fair percentage of c causing their light to red-shift into the IR frequencies. The reason why they are building the James Webb telescope. Some of it may be due to the heating of dust but that is not the main reason why they are only observable in IR


No. If you look into this the galaxies are distant but still low redshift, most below z~1. So at most frequencies are halved. Herschel observes from about 40 microns so that light was emitted at 20 microns still well into the infrared, in this case Herschel observed at about 100 microns which was thus emitted at 50 microns. That light will have been emitted by dust. Dust is the reason they are bright. JWST works at shorter wavelengths and with much more distant galaxies, what applies to it does not apply here.
GSwift7
5 / 5 (2) Jun 10, 2013
No. If you look into this the galaxies are distant but still low redshift, most below z~1. So at most frequencies are halved. Herschel observes from about 40 microns so that light was emitted at 20 microns still well into the infrared


That's correct. Also, low frequencies aren't shifted as much as higher frequencies. As you correctly pointed out, it's a percentage thing, so a high frequency wave is shifted much more than a low frequency one.

Also, redshift isn't linear with distance. After the initial rapid inflationary period, expansion slowed down to almost nothing. It's just starting to speed back up again, but expansion is still slow right now. You don't see very much redshift on objects that are less than 10 billion LY away, but the redshift increases exponentially beyond that point.

The relative size of the universe over time looks kinda like a church bell, with the BB at the top and our present uinverse at the bottom, and the circumference representing the size.
Fleetfoot
5 / 5 (1) Jun 11, 2013
No. If you look into this the galaxies are distant but still low redshift, most below z~1.


In this article:

galaxies so remote that their light has been traveling towards us for over ninety percent of the age of the universe


A lookback time of 90% equates to z ~ 4.5.