Herschel indentifies Cosmic Infrared Background Sources

Looks like there's much in common between the Cosmic Infrared Background
(CIB) and its more famous counterpart, the Cosmic Microwave Background
(CMB). They both surround the Earth from all directions, and they are
similarly even in all directions too. It's possible that the objects
that produced the CIB are nearer to us than the objects that produced
the CMB, since the light hasn't stretched out as much. So it would be
interesting to see if the variations in the CMB and the CIB are similar
or different? If they're different, then that might have new
implications for Dark Matter and Dark Energy research.

NASA is due to launch an infrared observatory called WISE, which will do
nothing more than map the sky in infrared on a wide-field. Not sure if
it can detect at these CIB infrared frequencies though.

Yousuf Khan

Herschel Identifies Two Thirds of CIB Sources - This could lead to more
knowledge of galaxy formation - Softpedia
"Scientists operating the Herschel Space Telescope have recently
announced that they managed to identify some of the sources associated
with the CIB (Cosmic Infrared Background) that the observatory detected
a while back. The weak field surrounds the Earth from all directions,
and experts believe that it may hold yet-undeciphered clues about the
origins and evolutions of galaxies. According to German astrophysicists,
more than half of the constituting sources for the CIB have now been
individually resolved, and more are currently being analyzed,
ScienceDaily reports. "
http://news.softpedia.com/news/Hersc...s-130315.shtml

Herschel Space Telescope uncovers sources of cosmic infrared background
"Whereas visible light tells us about the stars in galaxies, the
far-infrared is emitted by cold dust that is hiding the newly formed
stars. Identifying these surprisingly numerous dusty galaxies has proven
difficult, though. Space telescopes are needed to detect far-infrared
emission, because it is absorbed by the Earth's atmosphere. Previous
infrared space telescopes have detected far-infrared light from only the
brightest of the galaxies forming this cosmic background. To glean any
information about the fainter objects, astronomers had to rely on
indirect evidence based on shorter wavelength radiation."
http://www.sciencedaily.com/releases...1220175052.htm

In article ,
Yousuf Khan writes:
Looks like there's much in common between the Cosmic Infrared Background
(CIB) and its more famous counterpart, the Cosmic Microwave Background
(CMB). They both surround the Earth from all directions, and they are
similarly even in all directions too.

The CIB is not "even" at anything close to the level of the CMB. As
the press release says, 2/3 of it is resolved into individual
sources.

It's possible that the objects
that produced the CIB are nearer to us than the objects that produced
the CMB, since the light hasn't stretched out as much.

A funny way of looking at it. To oversimplify, the CMB measures
density fluctuations at the time of recombination. The CIB measures
the integral of star formation over the past history of the Universe.
Star formation did indeed occur rather later in time than
recombination, and the redshift is therefore lower and distance
smaller.

If they're different, then that might have new
implications for Dark Matter and Dark Energy research.

The CIB doesn't directly say anything about dark matter or dark
energy, though star formation may have happened earlier in regions of
large dark matter concentration. I would expect any CIB evidence
bearing on dark matter to be rather indirect, but I've certainly been
wrong before.

NASA is due to launch an infrared observatory called WISE, which will do
nothing more than map the sky in infrared on a wide-field.

Launched Dec 12:
http://www.nasa.gov/mission_pages/WI...e20091214.html
The spacecraft is in the right orbit, and the rumor mill says
everything is checking out fine so far, but the cover doesn't come
off the telescope until next week.

Not sure if
it can detect at these CIB infrared frequencies though.

WISE will observe at 3.4 and 4.6 microns, where the CIB might be
detectable, and at 12 and 22 microns, where it won't be. However,
even at the shorter wavelengths, my expectation is that its angular
resolution will be too low to say much about the CIB. As I say,
though, I've been wrong before. The WISE PI is one of the world's
experts on the CIB, so if there's anything WISE can do on the
subject, I'm sure he's thought of it.

--
Help keep our newsgroup healthy; please don't feed the trolls.
Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA

On Dec 21, 5:35*am, Yousuf Khan wrote:
Looks like there's much in common between the Cosmic Infrared Background
* (CIB) and its more famous counterpart, the Cosmic Microwave Background
(CMB). They both surround the Earth from all directions, and they are
similarly even in all directions too. It's possible that the objects
that produced the CIB are nearer to us than the objects that produced
the CMB, since the light hasn't stretched out as much. So it would be
interesting to see if the variations in the CMB and the CIB are similar
or different? If they're different, then that might have new
implications for Dark Matter and Dark Energy research.

NASA is due to launch an infrared observatory called WISE, which will do
nothing more than map the sky in infrared on a wide-field. Not sure if
it can detect at these CIB infrared frequencies though.

* * * * Yousuf Khan

Herschel Identifies Two Thirds of CIB Sources - This could lead to more
knowledge of galaxy formation - Softpedia
"Scientists operating the Herschel Space Telescope have recently
announced that they managed to identify some of the sources associated
with the CIB (Cosmic Infrared Background) that the observatory detected
a while back. The weak field surrounds the Earth from all directions,
and experts believe that it may hold yet-undeciphered clues about the
origins and evolutions of galaxies. According to German astrophysicists,
more than half of the constituting sources for the CIB have now been
individually resolved, and more are currently being analyzed,
ScienceDaily reports. "http://news.softpedia.com/news/Herschel-Identifies-Two-Thirds-of-CIB-...

Herschel Space Telescope uncovers sources of cosmic infrared background
"Whereas visible light tells us about the stars in galaxies, the
far-infrared is emitted by cold dust that is hiding the newly formed
stars. Identifying these surprisingly numerous dusty galaxies has proven
difficult, though. Space telescopes are needed to detect far-infrared
emission, because it is absorbed by the Earth's atmosphere. Previous
infrared space telescopes have detected far-infrared light from only the
brightest of the galaxies forming this cosmic background. To glean any
information about the fainter objects, astronomers had to rely on
indirect evidence based on shorter wavelength radiation."http://www.sciencedaily.com/releases/2009/12/091220175052.htm

Dark molecular H2 and He is just about everywhere, in photon absorbing
spots 1e15/m3 (1e9/cm3). This should account for most of the missing
mass of our universe, especially if this density increases with
distance and/or age (thus far there's no reason to think it doesn't).

~ BG

Steve Willner wrote:
In article ,
Yousuf Khan writes:
Looks like there's much in common between the Cosmic Infrared Background
(CIB) and its more famous counterpart, the Cosmic Microwave Background
(CMB). They both surround the Earth from all directions, and they are
similarly even in all directions too.

The CIB is not "even" at anything close to the level of the CMB. As
the press release says, 2/3 of it is resolved into individual
sources.

It does seem to me that it's coming from a more evolved version of the
universe. So things must have been coalescing.

It's possible that the objects
that produced the CIB are nearer to us than the objects that produced
the CMB, since the light hasn't stretched out as much.

A funny way of looking at it. To oversimplify, the CMB measures
density fluctuations at the time of recombination. The CIB measures
the integral of star formation over the past history of the Universe.
Star formation did indeed occur rather later in time than
recombination, and the redshift is therefore lower and distance
smaller.

Has anyone detected a Cosmic Radio Background, which would be even
earlier than the CMB?

If they're different, then that might have new
implications for Dark Matter and Dark Energy research.

The CIB doesn't directly say anything about dark matter or dark
energy, though star formation may have happened earlier in regions of
large dark matter concentration. I would expect any CIB evidence
bearing on dark matter to be rather indirect, but I've certainly been
wrong before.

Well, the CMB bearing on Dark Matter & Energy is pretty indirect too, so
I would expect the CIB would be just as indirectly useful.

Not sure if
it can detect at these CIB infrared frequencies though.

WISE will observe at 3.4 and 4.6 microns, where the CIB might be
detectable, and at 12 and 22 microns, where it won't be. However,
even at the shorter wavelengths, my expectation is that its angular
resolution will be too low to say much about the CIB. As I say,
though, I've been wrong before. The WISE PI is one of the world's
experts on the CIB, so if there's anything WISE can do on the
subject, I'm sure he's thought of it.


It was my understanding that the CIB consists mainly of the longer
wavelength IR rather than the shorter IR? I would've assumed that it was
closer to the microwave spectrum than towards the visible spectrum.

Yousuf Khan

SW The CIB is not "even" at anything close to the level of the CMB.

In article ,
Yousuf Khan writes:
It does seem to me that it's coming from a more evolved version of the
universe. So things must have been coalescing.

The Universe has grown clumpier with time, and indeed the CIB comes
from lower redshifts than the CMB.

Has anyone detected a Cosmic Radio Background, which would be even
earlier than the CMB?

The radio background is part of the CMB. The opacity of a hot plasma
increases as the square of wavelength, so at lower frequencies the
CMB is even more opaque than at the higher frequencies where it is
best observed.

It was my understanding that the CIB consists mainly of the longer
wavelength IR rather than the shorter IR? I would've assumed that it was
closer to the microwave spectrum than towards the visible spectrum.

There's a good, though somewhat out of date, discussion at
http://www.astro.ucla.edu/~wright/CIBR/
and a 2001 review article at
http://nedwww.ipac.caltech.edu/level...k2/frames.html

The CIB is hard to observe because of all the various "foregrounds:"
nearby sources of infrared radiation. Those foregrounds are minimal
at wavelengths of a few microns and also at a few hundred microns,
which is where the CIB was first detected (by COBE).

--
Help keep our newsgroup healthy; please don't feed the trolls.
Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA