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Oldest most distant Galaxy discovered to date

  1. Oct 8, 2012 #1
    MACS 1149-JD is the now the oldest, most distant Galaxy discovered to date. It began forming during the "dark ages" just 300Million years after the BB and was viewed here on earth as it was when the Universe was 500Million years old.

    http://www.nasa.gov/mission_pages/spitzer/news/spitzer20120919.html

    My question is, are these estimated ages still consistent with the age of the Universe, the time required for stars to form, and for the stars to form into a galaxy, albeit 1% the size of our own today?

    It will be very interesting to see whether the JW telescope sheds any new light on this as well as any even older galaxies.
     
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  3. Oct 8, 2012 #2

    marcus

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    Redshift 9.6.
    As the lead author Wei Zheng is quoted as saying, it is the earliest galaxy observed "with high confidence".
    There have been reports of of galaxies discovered with higher than 9.6 redshift but the estimate of redshift has been less certain. I think that's what he means. there are different ways to get a handle on the redshift, some more reliable than others.

    I don't see any inconsistency with present parameter values and the standard cosmic model.

    Try Jorrie's calculator:
    http://www.einsteins-theory-of-relativity-4engineers.com/CosmoLean_A25.html
    9.6 corresponds to a stretch factor of 10.6 so put that into Smax box.

    the expansion age will come out to be 500 million years.
    Seems like plenty of time for stars to get started and protogalaxy blobs to begin to form.

    But other people people may want to comment. I'll hunt for a link to the technical paper preprint (may still be unavailable because Nature likes scoops.)

    It is available after all, here is the link. I see they agree with Jorrie's calculator about the age of 500 My :biggrin:
    http://arxiv.org/abs/1204.2305
    A highly magnified candidate for a young galaxy seen when the Universe was 500 Myrs old
    Wei Zheng, Marc Postman, Adi Zitrin, John Moustakas, Xinwen Shu, Stephanie Jouvel, Ole Host, Alberto Molino, Larry Bradley, Dan Coe, Leonidas A. Moustakas, Mauricio Carrasco, Holland Ford, Narciso Benıtez, Tod R. Lauer, Stella Seitz, Rychard Bouwens, Anton Koekemoer, Elinor Medezinski, Matthias Bartelmann, Tom Broadhurst, Megan Donahue, Claudio Grillo, Leopoldo Infante, Saurabh Jha, Daniel D. Kelson, Ofer Lahav, Doron Lemze, Peter Melchior, Massimo Meneghetti, Julian Merten, Mario Nonino, Sara Ogaz, Piero Rosati, Keiichi Umetsu, Arjen van der Wel
    (Submitted on 10 Apr 2012)
    The early Universe at redshift z ~ 6-11 marks the reionization of the intergalactic medium, following the formation of the first generation of stars. However, those young galaxies at a cosmic age of ≤ 500 million years (Myr, at z ≥ 10) remain largely unexplored as they are at or beyond the sensitivity limits of current large telescopes. Gravitational lensing by galaxy clusters enables the detection of high-redshift galaxies that are fainter than what otherwise could be found in the deepest images of the sky. We report the discovery of an object found in the multi-band observations of the cluster MACS1149+22 that has a high probability of being a gravitationally magnified object from the early universe. The object is firmly detected (12 sigma) in the two reddest bands of HST/WFC3, and not detected below 1.2 μm, matching the characteristics of z ~ 9 objects. We derive a robust photometric redshift of z = 9.6 ± 0.2, corresponding to a cosmic age of 490 ± 15Myr (i.e., 3.6% of the age of the Universe). The large number of bands used to derive the redshift estimate make it one of the most accurate estimates ever obtained for such a distant object. The significant magnification by cluster lensing (a factor of ~15) allows us to analyze the object's ultra-violet and optical luminosity in its rest-frame, thus enabling us to constrain on its stellar mass, star-formation rate and age. If the galaxy is indeed at such a large redshift, then its age is less than 200 Myr (at the 95% confidence level), implying a formation redshift of zf ≤ 14. The object is the first z > 9 candidate that is bright enough for detailed spectroscopic studies with JWST, demonstrating the unique potential of galaxy cluster fields for finding highly magnified, intrinsically faint galaxies at the highest redshifts.
    39 Pages, 13 figures. Submitted to the Nature Journal.
     
    Last edited: Oct 8, 2012
  4. Oct 8, 2012 #3

    Chronos

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    The milky way is estimated to be 13.2 billion years old, meaning it formed about 500 million years after the big bang. The galaxy that Zheng reported would qualify as the youngest galaxy yet observed.
     
  5. Oct 8, 2012 #4

    marcus

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    Do you have a source for that estimate? I have to go out and just saw your post, curious about the MW age estimate and no time to google.
     
  6. Oct 9, 2012 #5

    RUTA

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    They use OmegaL = 0.7 and OmegaM = 0.3. Plugging these into LCDM I get time-of-emission = 3.66% time-of-reception for z = 9.6. Conversely, Einstein-deSitter gives 2.90%. To get their 3.6%, I need OmegaL = 0.67. Thanks for posting this, Tanelorn. We just finished EdS in my Modern Physics course and I was set to lecture on LCDM tomorrow, so I'll give this as a homework problem :smile:
     
  7. Oct 9, 2012 #6

    marcus

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    This brings up the question of when did our Milky Way galaxy form? How old is the disk?

    There would have been stars forming, and small clusters of stars, much earlier. It's assumed that our actual galaxy, the thin disk, assembled itself out of a kind of gathering "halo" of gas, stars, and small protogalaxy clusters of stars, that kind of fell together.

    This happens in computer simulations. A cloud of stuff condenses and if there is an overall average rotation then it can eventually form a diskshaped galaxy like our.
    Surrounded by whatever halo and satellite clusters didn't fall in and get trapped yet by the disk.

    This is the third of a series of 3 papers published in 2005 attempting to date the formation of Milkyway galaxy disk:
    http://arxiv.org/abs/astro-ph/0506458

    The oldest STARS in the surrounding halo are much older than the galaxy itself.
    It's reasonable to assume they go back to around year 500 million when the first stars were forming in lots of places. that is about 13.2 billion years ago.

    At that time the galaxy disk would probably not have formed. That would take a lot more of the slow gathering assembly process. This paper estimates that the disk formed around 8.8 billion years ago.

    They arrive at that by measuring isotope concentrations in disk stars. there is uncertainty in the estimate, they give it as 8.8±1.7 billion years. If we go with their 8.8 figure then the disk formed around year 4.9 billion.

    So roughly speaking the disk formed around 4.4 billion years AFTER the first stars lit up. That's assuming this paper is right.
     
    Last edited: Oct 9, 2012
  8. Oct 9, 2012 #7

    Chronos

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    Last edited: Oct 9, 2012
  9. Oct 9, 2012 #8

    marcus

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    I think I already indicated that there are halo stars in globular clusters way outside what we think of as the Milkyway and these globular clusters are older than the MW disk. Some halo stars go back 13.2 billion years. I said or suggested that earlier.

    A popular journalistic account was cited of an age estimate of a GLOBULAR CLUSTER called NGC 6397. Let's not confuse that with the galaxy itself.
    It's worth realizing that outlying globular clusters (of a few hundred thousand stars) are different from the galaxy (with its hundreds of BILLIONS of stars. They are very different objects and the globular clusters formed much much earlier.

    I think it's good to know that and get a more concrete visual picture of how a large galaxy like Milkyway formed. So I would like to make that point.

    I'd like to see some peer-review journal source dating the formation of the MW galaxy. So far I just found the article I linked to (which says 8.8 billion years old) and links to some previous journal articles. It would be interesting to know if any scholarly article disagrees. Pop journalism language can be imprecise and give a misleading impression.
     
  10. Oct 10, 2012 #9

    Chronos

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  11. Oct 10, 2012 #10

    Jorrie

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    I think the 500 million years still stands, but we must be careful of quoting lookback times like 13.2 Gyr. With the latest H0 and Omegam values, it may now be only 12.5 Gyr! I suppose one must somehow include H0 or h in the lookback times quoted.
     
  12. Oct 10, 2012 #11

    marcus

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    Good! One of these is peer-review, published in Nature. the other two are popular so let's look at this one: The Age of the Milky Way Inner Halo
    Jason Kalirai (STScI)
    (Submitted on 30 May 2012 (v1), last revised 21 Jun 2012 (this version, v2))
    The Milky Way galaxy is observed to have multiple components with distinct properties, such as the bulge, disk, and halo. Unraveling the assembly history of these populations provides a powerful test to the theory of galaxy formation and evolution, but is often restricted due to difficulties in measuring accurate stellar ages for low mass, hydrogen-burning stars. Unlike these progenitors, the "cinders" of stellar evolution, white dwarf stars, are remarkably simple objects and their fundamental properties can be measured with little ambiguity from spectroscopy. Here I report observations and analysis of newly formed white dwarf stars in the halo of the Milky Way, and a comparison to published analysis of white dwarfs in the well-studied 12.5 billion-year-old globular cluster Messier 4. From this, I measure the mass distribution of the remnants and invert the stellar evolution process to develop a new relation that links this final stellar mass to the mass of their immediate progenitors, and therefore to the age of the parent population. By applying this technique to a small sample of four nearby and kinematically-confirmed halo white dwarfs, I measure the age of local field halo stars to be 11.4 +/- 0.7 billion years. This age is directly tied to the globular cluster age scale, on which the oldest clusters formed 13.5 billion years ago. Future (spectroscopic) observations of newly formed white dwarfs in the Milky Way halo can be used to reduce the present uncertainty, and to probe relative differences between the formation time of the last clusters and the inner halo.

    As was said earlier halo stars are older than disk and outlying *globular clusters* are even older. Wikipedia has a nice article about globular clusters. They are a distinct type of object from spiral galaxies :biggrin: And Milkyway has a swarm of glob clusters around it scores of them as I recall.

    Let's compare this article's figure for inner halo of 11.4 billion years ± 0.7 with the estimate of the age of the disk which I found earlier 8.8 ± 1.7. Inner halo is not as old as the globular clusters (which are often around 13.2 billion years old) But still the inner halo is older than the galaxy proper--the main thing we think of as the galaxy--which the halo surrounds.
     
  13. Oct 10, 2012 #12

    marcus

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    Good point. A lot of the estimates depend on what is assumed for Hubble parameter--from which the overall age is calculated. I've been assuming a 13.7 billion year age. But there is that new estimate, when and if it is generally accepted we'll have to change a lot of these numbers.
    As you suggest, a lot of the journal articles express their results in terms of the dimensionless number "h" which equals 0.71 if the H0 parameter is 71 km/s per Mpc. so then their results don't get out of date so easily. Whatever the reader thinks "h" is he plugs it in and that's the answer.

    But what I'm looking for is a rough idea of the age of what we normally think of as the MW galaxy, the big main disk with its spiral arms and its central bulge. (not the swarm of gnat-size glob clusters in surrounding neighborhood).
    I don't need an estimate that's especially accurate. Let's look at how the 8.8 billion year age was derived.

    The age of the Galactic thin disk from Th/Eu nucleocosmochronology III. Extended sample

    E.F. del Peloso (1 and 2), L. da Silva (1), G.F. Porto de Mello (2), L.I. Arany-Prado ((1)Observatorio Nacional/MCT, Rio de Janeiro, Brazil, (2) Observatorio do Valongo/UFRJ, Rio de Janeiro, Brazil)
    (Submitted on 20 Jun 2005)
    The first determination of the age of the Galactic thin disk from Th/Eu nucleocosmochronology was accomplished by us in Papers I and II. The present work aimed at reducing the age uncertainty by expanding the stellar sample with the inclusion of seven new objects - an increase by 37%. A set of [Th/Eu] abundance ratios was determined from spectral synthesis and merged with the results from Paper I. Abundances for the new, extended sample were analyzed with the aid of a Galactic disk chemical evolution (GDCE) model developed by us is Paper II. The result was averaged with an estimate obtained in Paper II from a conjunction of literature data and our GDCE model, providing our final, adopted disk age T_G = (8.8 +/- 1.7) Gyr with a reduction of 0.1 Gyr (6%) in the uncertainty. This value is compatible with the most up-to-date white dwarf age determinations (<~ 10 Gyr). Considering that the halo is currently presumed to be (13.5 +/- 0.7) Gyr old, our result prompts groups developing Galactic formation models to include an hiatus of (4.7 +/- 1.8) Gyr between the formation of halo and disk.
    Comments: 7 pages, 5 Postscript figures, accepted for publication in Astronomy & Astrophysics
    More papers about Thorium/Europium dating of Milkyway disk stars.
    http://arxiv.org/abs/astro-ph/0411698
    http://arxiv.org/abs/astro-ph/0411699
     
    Last edited: Oct 10, 2012
  14. Oct 10, 2012 #13

    Chronos

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    It appears we agree to disagree. There is a staggering amount of data that remains to be fleshed out. I really enjoy exchanging views with you, marcus.
     
  15. Oct 11, 2012 #14
    Thanks for replies guys. On a slightly related question, is it actually possible for a new galaxy to begin forming at the presen time, or do the intial conditions required for it to form no longer exist? Or perhaps the presence and gravitational pull of other large mature galaxies prevents this by accumulating stars and stellar matter into themselves?
     
  16. Oct 12, 2012 #15

    Chronos

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    It appears you need a super massive black hole to seed the formation of a large galaxy, like the milky way. The conditions necessary to evolve a super massive black hole are probably a lot less favorable than they were in the early universe - especially if supermassive black holes evolved from primordial black holes orginated during the big bang.
     
  17. Oct 12, 2012 #16
    Chronos, so a super massive black is requried for a galaxy to form, without one, growth is limited to something the size of a globular cluster? These supermassive black holes could have began during the BB or as a result of the collapse of very short lived first generation of stars. If I understand you correctly, it is interesting that the initial parts of all galaxies are almost the exact same age.

    Marcus, this 12.5Gyrs figure would be inconsistant with this 9.6 redshift observation? Seems there is alot resting on the JW telescope. Will it be powerful enough to answer these questions with certainty? Perhaps it will just push the uncertainty back to an earlier age..
     
  18. Oct 12, 2012 #17

    marcus

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    T, there is no "12.5Gyrs figure" coming up that I know of. And no inconsistency I can see surrounding the 9.6 redshift observation.
    Wendy Freedman and Barry Madore et al have some preliminary new Cepheid numbers. Jorrie already gave the link.
    http://arxiv.org/abs/1208.3281
    I reviewed them and they lead to an estimate of the the age that is around 13.0 Gy plus or minus roughly 0.6 Gy. That's the variation I got by varying the Freedman et al estimates according to their own state uncertainty. maybe the margin of uncertainty more than ±0.6 Gy. somebody else might be able to get more slack, but it's something like that.

    WHEN I USE THE CENTRAL VALUES of their numbers NOT INCLUDING THEIR UNCERTAINTIES then I get an expansion age of 12.985 Gy, that is essentially 13.0 Gy. this is not out of line with what Ned Wright got by averaging a lot of estimates people have made over the past 10 years or more. See his FAQ on the age of the universe, estimated various different ways.

    The errorbars on all these numbers are pretty broad. I don't see any chance of actual contradictions. Also Freedman et al stuff has not been confirmed. They still have a ways to go and their final results may differ from the preliminary stuff they just published.

    Suppose you change the Ho according to Freedman et al preliminary findings. Then the age associated with 9.6 redshift changes too, more or less in harmony with the estimated age of expansion.

    Great progress is being made observationally, but I sometimes sense a tendency for people to overdramatize and make it sound more melodramatic. Yes of course we need to build and use the JW telescope, our astronomers do that is. We should support this passionately, for a lot of reasons. But for a lot of reasons not just to reduce imprecision about the age of expansion and the timetable of structure formation.

    If anyone wants to play around with the central values of the parameters taken from the new Freedman et al. Here they are:
    Ho = 74.3
    Omega_matter = 0.278
    Omega_Lambda = 0.729

    That is what leads to an age = 12.985

    they actually got a central value of Omega_total = 1.007 which of course leads to a finite volume universe. Very big, essentially like flat infinite for all practicals, but nevertheless spatially finite volume hypersphere. (not to take too seriously :biggrin: but that's what they got FWIW.)
     
    Last edited: Oct 13, 2012
  19. Oct 12, 2012 #18

    Jorrie

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    I originally mentioned the 12.5 as a lower limit, but as Marcus said, the median age is around 13 Gyr. The lookback time to the z=9.6 galaxy will be about 12.5 Gyr with the "new" values.
     
  20. Oct 13, 2012 #19

    NWH

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    I can't wait for fifty or so years time to see our advancements in optical and digital photographic technology. Perhaps one day we might see this galaxy in some detail.
     
  21. Oct 13, 2012 #20

    marcus

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    Yes! That is about what I get too! about, as their lower limit on the present age. Sort of 13.0 Gy plus/minus 0.5 or 0.6. Just back of envelope. I am getting to like that Freedman et al paper quite a lot. It is exciting that they can use Cepheids farther out than before.

    Why don't I just copy the abstract of that Freedman et al paper? this is what Jorrie was linking to in a couple of posts in this thread.
    http://arxiv.org/abs/1208.3281
    Carnegie Hubble Program: A Mid-Infrared Calibration of the Hubble Constant
    Wendy L. Freedman, Barry F. Madore, Victoria Scowcroft, Chris Burns, Andy Monson, S. Eric Persson, Mark Seibert, Jane Rigby
    (Submitted on 16 Aug 2012)
    Using a mid-infrared calibration of the Cepheid distance scale based on recent observations at 3.6 um with the Spitzer Space Telescope, we have obtained a new, high-accuracy calibration of the Hubble constant. We have established the mid-IR zero point of the Leavitt Law (the Cepheid Period-Luminosity relation) using time-averaged 3.6 um data for ten high-metallicity, Milky Way Cepheids having independently-measured trigonometric parallaxes. We have adopted the slope of the PL relation using time-averaged 3.6 um data for 80 long-period Large Magellanic Cloud (LMC) Cepheids falling in the period range 0.8 < log(P) < 1.8. We find a new reddening-corrected distance to the LMC of 18.477 +/- 0.033 (systematic) mag. We re-examine the systematic uncertainties in H0, also taking into account new data over the past decade. In combination with the new Spitzer calibration, the systematic uncertainty in H0 over that obtained by the Hubble Space Telescope (HST) Key Project has decreased by over a factor of three. Applying the Spitzer calibration to the Key Project sample, we find a value of H0 = 74.3 with a systematic uncertainty of +/-2.1 (systematic) km/s/Mpc, corresponding to a 2.8% systematic uncertainty in the Hubble constant. This result, in combination with WMAP7 measurements of the cosmic microwave background anisotropies and assuming a flat universe, yields a value of the equation of state for dark energy, w0 = -1.09 +/- 0.10. Alternatively, relaxing the constraints on flatness and the numbers of relativistic species, and combining our results with those of WMAP7, Type Ia supernovae and baryon acoustic oscillations yields w0 = -1.08 +/- 0.10 and a value of N_eff = 4.13 +/- 0.67, mildly consistent with the existence of a fourth neutrino species.
    Comments: 27 pages, 8 figures, Accepted for publication in Ap J
     
    Last edited: Oct 13, 2012
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