APOD: HUDF Infrared: Dawn of the Galaxies (2009 Dec 09)

[APOD Robot]

HUDF Infrared: Dawn of the Galaxies

Explanation: When did galaxies form? To help find out, the deepest near-infrared image of the sky ever has been taken of the same field as the optical-light Hubble Ultra Deep Field (HUDF) in 2004. The new image was taken this summer by the newly installed Wide Field Camera 3 on the refurbished Hubble Space Telescope. Faint red smudges identified on the above image likely surpass redshift 8 in distance. These galaxies therefore likely existed when the universe was only a few percent of its present age, and may well be members of the first class of galaxies. Some large modern galaxies make a colorful foreground to the distant galaxies. Analyses by the HUDF09 team indicate that at least some of these early galaxies had very little interstellar dust. This early class of low luminosity galaxies likely contained energetic stars emitting light that transformed much of the remaining normal matter in the universe from a cold gas to a hot ionized plasma.

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[neufer]

Just as I'm starting to feel a little proud about my 2059 Asterisk posts I look out there and begin to question the importance of my accomplishment in the grand scheme of the universe.

[John Carswell]

Please forgive my ignorance. I have no education in astronomy. I just look at APOD with my first coffee and pipe every morning to keep a perspective on life. I have always wondered; If the light we see was emitted by these galaxies 15 billion years ago and the universe was smaller fifteen billion years ago, why don't they appear to be much closer?

[Storm_norm]

like that sticker on the passenger side view mirror, "objects are closer than they appear." the sticker on the hubble telescope mirror - "objects are farther than they appear, and may not currently exist."

my question is... if the photons reaching the telescope have a redshift of 8 or greater, what velocity did the object have receding from us?

us - meaning our galaxy.

[casusbelli]

re: today's APD, I understand why (according to Big Bangers) the "faint red smudges" are very distant and so red-shifted. But...what then are the more numerous faint WHITE smudges? Tiny but closer galaxies? Look at the picture... New class of objects? Why aren't they all red-shifted? They sure aren't foreground bodies.

[geckzilla]

re: today's APD, I understand why (according to Big Bangers) the "faint red smudges" are very distant and so red-shifted. But...what then are the more numerous faint WHITE smudges? Tiny but closer galaxies? Look at the picture... New class of objects? Why aren't they all red-shifted? They sure aren't foreground bodies.

Why can't they be in the foreground? Galaxies come in many different shapes and sizes.

[apodman]

Why do think red-shifted objects are red? All wavelengths become longer. Blue becomes green or yellow or red depending on the amount of shift. Green becomes yellow or red, ultraviolet becomes visible, visible becomes infrared, etc. You have to see the wavelength change for known lines in the spectrum to "see" a red shift.

[neufer]

Please forgive my ignorance. I have no education in astronomy. I just look at APOD with my first coffee and pipe every morning to keep a perspective on life. I have always wondered; If the light we see was emitted by these galaxies 15 billion years ago and the universe was smaller fifteen billion years ago, why don't they appear to be much closer?

But they DO appear to be closer than they should... or at least they appear to be bigger than they should considering their distance.

The most distant object we can detect is the cosmic microwave background plasma at a redshift is about z = 1089.

The full diameter of the cosmic microwave background plasma amounts to only 72 million light-years and yet it appears to loom much larger (~27.4 billion light-years in diameter).

[casusbelli]

Art/neufer-
can you give me a link or reference to that last sentence? I'm not in-the-know on that subtopic. thanks, c

[neufer]

Art/neufer-
can you give me a link or reference to that last sentence? I'm not in-the-know on that subtopic. thanks, c

Size of the observable universe

<<The Universe has expanded to 1292 times the size it was when the CMBR photons were released. Hence, the most distant matter that is observable at present, 46 billion light-years away, was only 36 million light-years away from the matter that would eventually become Earth when the microwaves we are currently receiving were emitted.>>

Extragalactic observations

<<The most distant objects exhibit larger redshifts corresponding to the Hubble flow of the universe. The largest observed redshift, corresponding to the greatest distance and furthest back in time, is that of the cosmic microwave background radiation; the numerical value of its redshift is about z = 1089 (z = 0 corresponds to present time), and it shows the state of the Universe about 13.7 billion years ago, and 379,000 years after the initial moments of the Big Bang.>>

[bystander]

re: today's APD, I understand why (according to Big Bangers) the "faint red smudges" are very distant and so red-shifted. But...what then are the more numerous faint WHITE smudges? Tiny but closer galaxies? Look at the picture... New class of objects? Why aren't they all red-shifted? They sure aren't foreground bodies.

They are all red shifted.

... the deepest near-infrared image of the sky ever ...

The photo was taken with the new WFC3/IR camera on Hubble in late August 2009 during a total of four days of pointing for 173,000 seconds of total exposure time. Infrared light is invisible and therefore does not have colors that can be perceived by the human eye. The colors in the image are assigned comparatively short, medium, and long, near-infrared wavelengths (blue, 1.05 microns; green, 1.25 microns; red, 1.6 microns). The representation is "natural" in that blue objects look blue and red objects look red. The faintest objects are about one-billionth as bright as can be seen with the naked eye.

Hubble's deepest view of Universe!

[geckzilla]

The photo was taken with the new WFC3/IR camera on Hubble in late August 2009 during a total of four days of pointing for 173,000 seconds of total exposure time. Infrared light is invisible and therefore does not have colors that can be perceived by the human eye. The colors in the image are assigned comparatively short, medium, and long, near-infrared wavelengths (blue, 1.05 microns; green, 1.25 microns; red, 1.6 microns). The representation is "natural" in that blue objects look blue and red objects look red. The faintest objects are about one-billionth as bright as can be seen with the naked eye.

I have been wondering since I read this what the colors do mean in the image. I knew already that the colors were assigned. The explanation suggests that all the deep, dim, red objects are the farthest away. This causes one to assume that the less red, orange colored ones aren't as far, and then yellow ones are even less far, and then the white ones are the closest. But the quote above makes me wonder if my assumption is true? Is it only the dark red ones which are known to be far and then the others have an unknown distance? I'm probably lacking some fundamental understanding which is blocking me on this.

[bystander]

I have been wondering since I read this what the colors do mean in the image. I knew already that the colors were assigned. The explanation suggests that all the deep, dim, red objects are the farthest away. This causes one to assume that the less red, orange colored ones aren't as far, and then yellow ones are even less far, and then the white ones are the closest. But the quote above makes me wonder if my assumption is true? Is it only the dark red ones which are known to be far and then the others have an unknown distance? I'm probably lacking some fundamental understanding which is blocking me on this.

I think there may be some RGB spectrum coloring, but I suspect the red objects are the farthest, and blue the closest.

[geckzilla]

Check this out. This is at the top of the deep field image. It's probably just two objects overlapping, but wouldn't it be interesting if there was a spiral galaxy with two distinct cores? Someone will probably come along and tell me it's not possible.

[drollere]

i have two rather technical questions about deep space imagery in general.

* galactic density. as we image galaxies farther back in time, we see the galactic distribution during those eras. presumably, at the distance of the microwave background, we see no galaxies, because they had not formed yet. but if galaxies did not form simultaneously, then we should see either (1) more/fewer galaxies at different time periods, (2) fewer "late evolving" elliptical galaxies earlier in time, up to the point of the first wave of galactic formation, and which point elliptical galaxies should not be visible. do we see any distance related differences in galactic distribution, either as density of galaxies of any kind (averaged over the entire extragalactic sky) or density variation in the type of galaxies?

* optical correction. going further back in time means that the same area of sky images a smaller and smaller volume of space. (if it were possible to see the singularity, then a single point would cover the entire celestial sphere.) therefore the procedure of counting galaxies or estimating the size of microwave anomalies requires a time-variable metric of angular size. is that generally a problem recognized in interpreting these distant images? does it produce an enlargement of the galactic image? how otherwise is it addressed/handled/corrected when interpreting these deep space images?

[drollere]

Check this out. This is at the top of the deep field image. It's probably just two objects overlapping, but wouldn't it be interesting if there was a spiral galaxy with two distinct cores? Someone will probably come along and tell me it's not possible.

colliding galaxies, galaxies fusing through mutual gravitational attraction, are not at all uncommon.

[geckzilla]

Check this out. This is at the top of the deep field image. It's probably just two objects overlapping, but wouldn't it be interesting if there was a spiral galaxy with two distinct cores? Someone will probably come along and tell me it's not possible.

colliding galaxies, galaxies fusing through mutual gravitational attraction, are not at all uncommon.

Of course, but I was thinking more about one that had come to a sort of stable state with the two cores still intact.

[drollere]

Of course, but I was thinking more about one that had come to a sort of stable state with the two cores still intact.

occam recommends that you go with something simple until the data force you to contrive something more complicated. the image is pretty fuzzy, and the galaxies are pretty far away, one galaxy could be superimposed on the other, or those detached spiral arms could show a tidal effect. somewhere in apod is a composite image of many colliding galaxies; good basis for comparison.

[geckzilla]

Of course, but I was thinking more about one that had come to a sort of stable state with the two cores still intact.

occam recommends that you go with something simple until the data force you to contrive something more complicated. the image is pretty fuzzy, and the galaxies are pretty far away, one galaxy could be superimposed on the other, or those detached spiral arms could show a tidal effect. somewhere in apod is a composite image of many colliding galaxies; good basis for comparison.

...Which is why I was skeptical in my original post. You can just say it's extremely unlikely or impossible and I'm good with that.

[bystander]

...Which is why I was skeptical in my original post. You can just say it's extremely unlikely or impossible and I'm good with that.

Actually your idea is not as far fetched as they would have you believe ...

Hubble Space Telescope Finds a Double Nucleus in the Andromeda Galaxy

[The Code]

Its a jungle out there.

18 billion solar mass BH. That,s 1.2 Billion solar masses every billion years. That,s a lot of galaxy merges don,t you think?

MS

[DavidLeodis]

Such images as this one bring out to me both the ultra mind-boggling awesomeness and enormousness of the Universe. The image only covers a tiny area yet there are galaxies galore. Our Universe is beautiful but also a bit scary. It's also .

[drollere]

checked in for an answer to my questions about variations in the galaxy population and optical "magnification" of deep space images. didn't see one ... is that a dead question or should i check back for a response?

[bystander]

Off topic bbt. dm. de. redshift split to here