As we improve our ability to look back to the early universe, the changes we see in galaxies at this period compared to later eras are striking. A new study, using data from the Hubble Space Telescope’s Wide Field Planetary Camera 3 has been gathering infrared imagery back to a period as early as 480 million years after the Big Bang. What stands out in this work is the rate of star formation. In the period between 480 million to 650 million years after the Big Bang, the rate of star birth increased ten times. Garth Illingworth (UC-Santa Cruz) calls the result “…an astonishing increase in such a short period, just 1 percent of the current age of the universe.”
Moreover, the number of galaxies themselves showed a marked change. Says Illingworth:
“We’re getting back very close to the first galaxies, which we think formed around 200 to 300 million years after the Big Bang… Our previous searches had found 47 galaxies at somewhat later times when the universe was about 650 million years old. However, we could only find one galaxy candidate just 170 million years earlier. The universe was changing very quickly in a short amount of time.”
Among the galaxies studied is a candidate that appears to be the most distant galaxy ever observed, some 13.2 billion light years from Earth. The newly found galaxy has a redshift value (z) of 10.3, which places it just 480 million years after the birth of the universe. Remember that these redshifts are not Doppler shifts, which would be caused by the physical motion of the galaxies as they moved away from us in space. Rather, they are ‘cosmological’ redshifts. The photons being emitted from the galaxies are stretched as they travel through an expanding spacetime.
Image: The farthest and one of the very earliest galaxies ever seen in the universe appears as a faint red blob in this ultra-deep-field exposure taken with NASA’s Hubble Space Telescope. This is the deepest infrared image taken of the universe. Based on the object’s color, astronomers believe it is 13.2 billion light-years away. (Credit: NASA, ESA, G. Illingworth (University of California, Santa Cruz), R. Bouwens (University of California, Santa Cruz, and Leiden University), and the HUDF09 Team).
The concept goes back to the Dutch astronomer Willem de Sitter, who went to work on Einstein’s general theory of relativity not long after it was published and discovered that a stretching of space itself would cause light from more distant objects to appear redder than light from nearby objects. Hubble’s later observations could then be explained using de Sitter’s concept as indications that space and the photons in it are being stretched as the universe expands. David Weintraub tackles the subject in depth in his new book How Old Is the Universe (Princeton University Press, 2011:
Space that is empty of matter does not and never did exist. The distances between galaxies, galaxies being dense pockets of matter in an otherwise rarefied universe, are increasing with time but the galaxies themselves are not speeding through space. On the grandest scale (that is, ignoring small local motions that all galaxies have as they interact with nearby galaxies), galaxies are fixed in their locations in space. They do not move through space. Yet the distances between galaxies grow rapidly because the fabric of space in between the galaxies is continually being stretched, taffy-like, with the galaxies patiently riding along at fixed locations in the taffy.
Sorry for the digression, but I finished Weintraub’s book a few weeks back and have been paging back through it now and then with these concepts in mind. I’ll review the book soon. In any case, I hope the digression helps to put the new work in context, and points out how significant finding a galaxy with a z value of 10.3 is. The finding and the analysis of galaxies at slightly lower redshifts allows us to start building up a population of very early galaxies, and that should offer useful information re how galaxies form, particularly because the number of galaxies in this period increases so rapidly.
All of this work involves data originally collected from the Hubble Ultra Deep Field (a small region in the constellation Fornax) which were gathered during two four-day stretches in 2009 and 2010, focusing Hubble’s WFC3 infrared camera on a tiny part of the HUDF for a total exposure time of 87 hours. What also emerges from this work is that galaxies this faint and small (the Milky Way is 100 times larger) will need the resources of the James Webb Space Telescope for follow-up study beyond redshift 10.
Paul! How could you! You confused the Light Travel Time with the actual distance to the putative Galaxy! Light from it has travelled to us for 13.2 billion years, but the Cosmos expanded in the intervening time, so the distance at a redshift of 10.3 is more like 30 billion light-years. Here’s Ned Wright’s Cosmology Calculator for Light Travel Time…
http://www.astro.ucla.edu/~wright/DlttCalc.html
…which gives the following result for 13.2 billion years…
For Ho = 71, OmegaM = 0.270, Omegavac = 0.730, z = 10.259
* It is now 13.665 Gyr since the Big Bang.
* The age at redshift z was 0.465 Gyr.
* The light travel time was 13.200 Gyr.
* The comoving radial distance, which goes into Hubble’s law, is 9716.3 Mpc or 31.690 Gly.
* The comoving volume within redshift z is 3842.243 Gpc3.
* The angular size distance DA is 863.0 Mpc or 2.8146 Gly.
* This gives a scale of 4.184 kpc/”.
* The luminosity distance DL is 109397.7 Mpc or 356.811 Gly.
1 Gly = 1,000,000,000 light years or 9.461*1026 cm.
1 Gyr = 1,000,000,000 years.
1 Mpc = 1,000,000 parsecs = 3.08568*1024 cm, or 3,261,566 light years.
…so the distance to that Galaxy is the Co-Moving Radial Distance, currently 31.69 billion light years, based on the parameters for a Flat Universe (which it appears to be very nearly.)
Fun to play with for different parameters.
Adam, you’ve been tweaking me about this for years! But if I lead with a discussion of a galaxy that’s now 31.69 billion light years away, we open up an entirely different discussion. Maybe what I should start doing is throwing in Ned’s calculator with every such reference. Hmmm…
Might have have to send you to remedial school after dropping this clanger too…
…”light years after the birth of the Universe”…
for shame.
Well, I got my wish. Now lets just wait and see what what they have to say when JWST finds galaxies at redshifts corresponding (in the LCDM paradigm) to :-)
… less than 200 million years old. [my message got truncated at the ‘less-than’ symbol, sorry]
So has the luminosity and size of this galaxy been calculated using the correct distance? If the figures given are based on 13.2Gly, but the correct figure should have been over 30Gly, that would make it a lot more luminous and much larger than stated.
I’ve got a problem with the excerpt from the book, the “tacky” of space makes it sound like there is an aether ?!
I also think these galaxies are “really” moving: if we chased after one of them, we would have to accelerate to a velocity exceeding what we perceive it to be from here, before we would catch up. We would not get a free ride from expansion of the universe. That’s my understanding anyway.
Adam writes:
Mea culpa, but hey, I hadn’t had my first cup of coffee yet! Now fixed.
kzb writes:
Yes, the astronomers are using the right numbers. What Adam is talking about is the expansion of spacetime during the time it has taken for the light the astronomers are working with to reach us.
>Yes, the astronomers are using the right numbers. What Adam is talking about is the expansion of spacetime during the time it has taken for the light the astronomers are working with to reach us.
So, what are the observational consequences of this? Surely we can all agree that we can only see what we can see. That is, it makes no sense to talk about the “true” age, etc., of these remote galaxies when in fact we have no hope of observing such. Theory without observational consequences is just metaphysics. Admittedly, I may be completely missing the point of the discussion, but if it is just metaphysics, then it should be passed over in silence.
Hi Guys
Prof. Ned Wright’s Cosmology Tutorial explains the various distances involved in extragalactic astronomy…
Part 2: Homogeneity and Isotropy; Many Distances; Scale Factor
…which, interestingly, means the Luminosity Distance of the new Galaxy spotted at redshift z = 10.3 is a whopping 356.811 Giga-ly – due to the redshift making the light we see so much dimmer as the Universe expanded.
John Q, I agree really, these days it is unfortunately the case that you have to ruthlessly get to the bottom of EXACTLY HOW figures have been calculated -and this goes for all walks of life :)
Observational consequences I guess: at high redshifts, any error in the Hubble constant is going to multiply up like compound interest. Same probably goes for some other parameters in the calculation.
Astronomers can only work with photons they can detect, which makes the issue of the actual distance of this object as of today inconsequential. This is solid work, although subject to refinement and recalculation once we have better instrumentation (JWST) in space.
General relativity screwing with our notions of what we mean by distance and time again. Once we get to cosmological scales, we have to define what we mean by “distance” in the first place (as there are several possible choices), and most of the values you get out depend on what cosmological model you put in. That’s why you typically end up working with red-shift – it is more closely linked to the observable quantities.
At least on the interstellar scale you can mostly get away with special relativity which is far less mind-bending.
I’ve never got my head around why:
Special relativity says we cannot measure the velocity of any object with mass as being equal to or greater than “c”
There is no “ether”
Yet we routinely observe galaxies whose redshift corresponds to velocities greater than “c”.
I’m sure greater minds have reconciled these issues though.
What might not be reconciled properly with this topic is that the different distance measures and the differences between them are model-dependent. Whether the universe is open or closed makes a difference to the distance estimation.
What we have to be careful of here is circular logic. If these observations are used to illustrate the accelerating expansion of the universe, just be careful that very assumption is not “built in” to the distance calculation.
@kzb
You are considering a situation outside the domain where special relativity is valid. On the cosmological scale you need to be using general relativity.
Andy, yes that is the reason that is given, that is special relativity is not valid for cosmological scales. However it has always seemed deeply unsatisfactory to me that there is not one joined-up theory. To me, it makes it look that cosmology has not got it quite right yet.
Those galaxies are receding from us as a result of an explosion. There is explicitly NO “fabric of spacetime” in relativity to pull them along. That was one of the cornerstones of relativity.
kzb, SR is valid everywhere and GR is valid everywhere. You seem to be operating under a number of misconceptions. I strongly recommend cracking open a book on spacetime physics and learning some of the basics since this topic seems to interest you. Although none of us can know everything, ignorance of a topic does not make it untrue.
You’re probably right Ron S, I am no doubt labouring under some misconceptions, but that is AFTER I have tried to read some things on spacetime physics :)
kzb: well special relativity is a limiting case of general relativity, so fitting the two together is not a problem: special relativity applies when you do not have gravity to deal with. This is like the case of Newtonian physics versus special relativity: as velocities tend to zero the equations of special relativity become those of Newtonian mechanics.
The real problem is general relativity versus quantum theory (note that special relativity and quantum theory go together perfectly fine!)…
kzb,
Ah, you’ve tried. It is mind bending stuff. Unfortunately giving a good explanation takes time, and a good understanding of what exactly you know and are having difficulty with, and time to give explanations. Since there’s so much good material out there and you know your needs better than me, it seemed better to refer to outside material rather than spending time of my own, perhaps to uncertain success.
But perhaps a couple of points that might help you along. andy makes a good point re SR vs GR. Well, actually it’s a bit more complicated than that since SR is not entirely = to Newtonian dynamics at low velocities since in SR light has momentum. This gets into the energy-mass duality that SR unveiled.
SR = GR where the spacetime curvature is negligible. That is, there can be a strong gravitational field in which SR is a sufficient description, but only if the curvature is low: small gradient or, if you prefer, negligible tidal effects.
One thing that lots of people forget is that velocity is never the property of an object; it’s a quantity you *must* measure, and therefore depends on the relative motion between the observer and the observed. Relative motion is nothing new (the ancients understood it very well indeed, though they typically interpreted it differently). But in SR, relative motion takes on additional importance since it impacts dynamics (energy, momentum, etc.) in different ways.
Another important aspect to keep in mind is that these physics are primarily local in nature. The smaller the observer’s frame, the better. For example, c (photon velocity in a vacuum) is only valid when measured in an inertial frame. That means that the measuring equipment must be local, such as two close-spaced photo cells close together pointed towards a source but at slightly different distances from the source. And the frame cannot be accelerating or within a high curvature region. You then detect a light pulse and measure the time difference in the two detections to calculate c.
When you throw cosmology into the picture you have to deal with non-local physics that take into account the large-scale curvature of the universe, which depends on the model of the universe being employed, and the quality of the inference about distance, etc. Yet even so, a locally measured photon stream from the most-distant observed objects in the universe is always c.
The curvature does change the photon’s energy and path length. From here you get into weird discussions about how far away those sources “really” are, and just what those high red shifts “really” mean. But that’s another story entirely.
If that helps a little bit, great. If not, I’ll have to leave you to the literature on the subject.
Thanks Ron S and andy. I guess I need to go on a course. But I still think I have a valid point, and that is all the different distance measures are model-dependent. That is, the curvature of the universe depends on the mass density, which in turn affects how the distances are calculated.
kzb: “…all the different distance measures are model-dependent.”
Well, yes, to a degree. However these are not arbitrary. Experimental data and well-understood physics tightly constrain the allowable models. Feeling uncomfortable with the current state of the science is not an argument.
Well electromagnetic radiation certainly does not have low velocity, so maybe I can get out of this one… :)
andy, I wasn’t criticizing. It’s difficult to boil down a complex subject into just a few lines or paragraphs!
It seems that almost twice a month now there is a new claim for the most distant galaxy/ cluster which I love to read about, especially Paul’s enthusiasm : ) . What sometimes bothers me, however, are the interpretations of what is being seen. We are at the limits of the Hubble Deep Field now and I believe great latitude is involved concerning the interpretations of the data at such limits. The same is true of cosmic lensing. In this case it is this quote “in the period between 480 million to 650 million years after the Big Bang, the rate of star birth increased ten times.
When radio astronomy VLBI first started making important observations, early 70’s, there were a great number of claims concerning how the universe was different in the past which could not be explained by a steady-state model. In time these claims have changed, such as quasars “were only objects that were involved with the beginning of the universe, radio galaxies were evidence of galaxies being quite different in the early universe,” etc. etc.
When the Hubble first started making observations many of these old interpretations, originally used as arguments against a steady-state model, were reinterpreted, such as quasars are now the centers of active galaxies, radio galaxies often involve old elliptical galaxies, etc. etc. There were also a rash of papers at that time, maybe a hundred or so, claiming very old appearing galaxies at 8 to 10 billion light years. The interpretations of these galaxies has not changed since. It is clear to me that when the James Webb telescope goes up, maybe 2015 which is not too long from now, the same exact interpretations, concerning very old appearing galaxies, will be mad. I think those galaxies that we are now calling proto-galaxies and proto-clusters will be reinterpreted or mixed with very old appearing galaxies at the edge of what we presently believe to be the edge of the observable universe. Some of those astronomy groups making the last round of observations in the mid to late 90’s concerning “very old appearing galaxies” at the edge of the universe, will be in the best interpretive position to see the exact same types and ratios of “old appearing galaxies,” again. At that time I believe it will unfold within the following 5 years that at least the observable universe is in a steady-state condition and that a new cosmological model is needed.
Of course I made this same prediction in the early 90’s before the Hubble went up : )
My primary point is that at the edge of possible observations, which the Hubble Deep Field presently involves, science often “finds” samplings of whatever they are looking for — because too much interpretation of the data is needed to find anything else.
Forrest noble, I agree very much with your outlook. I’m not joining your campaign about the steady-state universe, but I am defending our right to skeptism about the present model.
Ron S If you were able to jump through a time warp say 1000 years into the future, how much of the current model would still survive?
I don’t think we know it all. If anyone thinks that cosmology is pretty-well settled, please have a read of the paper I link below. It is not written by a “woo-woo”, it is a professional in the field. I only started reading it the other day and it has blown me away already. For example, did you know that Hubble himself shied away from universal expansion later in life ? Also there looks to be some VERY big problems with the distances of QSO’s.
http://arxiv.org/PS_cache/astro-ph/pdf/0310/0310214v2.pdf
kzb, please don’t descend into setting up strawmen or putting words in my mouth. Of course it isn’t settled. However that is no justification for sneering at the good and exacting work that has been done.
I also suggest that you avoid your most recent attempt to use an ‘argument by authority’; there are ample examples of productive scientists, even Nobel laureates, that have subsequently turned towards outright nonsense. The speaker does not make the truth.
Are there fundamental uncertainties? Yes there are. There is much left to discover and I for one look forward to it all. Don’t look to me to defend the status quo, just the need for good scientific inquiry in preference to the promotion of deeply-held beliefs about what anyone feels *ought* to be true.
kzb,
I think your skepticism is well justified based upon my previous posting. I agree your link is a good example. You mentioned the Hubble Constant but in present cosmology there is no Hubble Constant. Using the dark energy idea, the present interpretation, the rate of the universe’s expansion has changed/ is changing over time. Now instead of the Hubble Constant they refer to it as the “average expansion rate” when doing calculations using the Hubble formula to calculate distances.
Of course I think all of this is probably wrong anyway. Instead my calculations and model assert that there is no expansion of the universe at all, also that the Hubble formula needs adjustment which accordingly would explain away dark energy. I also believe that correcting GR would explain away dark matter.
I think we are seeing the beginning of a new interpretation by astronomers, but not for the better. They are now beginning to claim that some of the distant universe/ galaxies have been naturally lensed by closer galaxies. I think the word “some,” which they are now using , will in time be changed to the word “most” after awhile concerning what will be observed at these distances in the future. This accordingly will be the wrong interpretation but I believe until they understand the details of a correct cosmological model, they will continue to search for explanations of old appearing galaxies at the greatest observable distances.
Of course there are other models that also might better explain the appearance of distant galaxies than a stead state model. But steady state models could seemingly have countless variations, at least one of which proposes a universe finite in both age and size with a singularity beginning which is my own model :) .