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Z=10 galaxy

  1. Apr 9, 2004 #1

    wolram

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    thanks to MARCUS.
    this discussion started in S B and LQG, i thought i had better move to
    a more appropriate place.
    the recent discovery of a Z=10 galaxy, if confirmed means it was
    was formed when our universe was only 500MYs old.
    this paper discuses the discovery.

    http://xxx.arxiv.cornell.edu/PS_cache/astro-ph/pdf/0403/0403327.pdf
     
    Last edited: Apr 9, 2004
  2. jcsd
  3. Apr 9, 2004 #2

    wolram

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    http://obswww.unige.ch/sfr/z10/text/Ga201.pdf
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    press release page.

    Using the ISAAC near-infrared instrument on ESO's Very Large Telescope, and the magnification effect of a gravitational lens, a team of French and Swiss astronomers [2] has found several faint galaxies believed to be the most remote known.

    Further spectroscopic studies of one of these candidates has provided a strong case for what is now the new record holder - and by far - of the most distant galaxy known in the Universe.

    Named Abell 1835 IR1916, the newly discovered galaxy has a redshift of 10 [3] and is located about 13,230 million light-years away. It is therefore seen at a time when the Universe was merely 470 million years young, that is, barely 3 percent of its current age.

    This primeval galaxy appears to be ten thousand times less massive than our Galaxy, the Milky Way. It might well be among the first class of objects which put an end to the Dark Ages of the Universe.

    This remarkable discovery illustrates the potential of large ground-based telescopes in the near-infrared domain for the exploration of the very early Universe.
     
    Last edited: Apr 9, 2004
  4. Apr 9, 2004 #3

    marcus

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    Dearly Missed

     
  5. Apr 9, 2004 #4

    wolram

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    MARCUS.
    the only articles i can find refer back to this one, but i get the
    impression that a Z=10 galaxy was predicted or at least hinted
    at sometime ago.
     
  6. Apr 9, 2004 #5

    wolram

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  7. Apr 9, 2004 #6

    wolram

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    http://origins.jpl.nasa.gov/library/roadmap97/science07.html


    The creation and dispersal of these heavy elements can be measured by observing the rates of supernovae (which should be observable to redshifts of z > 10, well within a billion years of the Big Bang), the strengths of spectral features around ancient star-forming regions, and in the integrated galactic light of established stars at redshifts z > 2. By comparing these data with the expected elemental yields from the stars producing the ultraviolet and far-infrared emission, also potentially observable to epochs beyond z > 10, we can reconstruct a coherent and consistent chronology of the formation and release of heavy elements in the universe.
     
    Last edited: Apr 9, 2004
  8. Apr 9, 2004 #7

    wolram

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    WMAP data shows first "objects" formed 200MYRs after the BB so we have
    a window of 300MYRs, for a lot happen?


    http://map.gsfc.nasa.gov/m_mm/sg_firstobj.html

    electrons in the early universe. WMAP is designed to detect polarized photons. In principal, their properties reveal the number of free electrons in the early universe and the ionization history of the universe. This enables astronomers to infer when the first objects in the universe formed that were capable of ionizing the gas in the universe. WMAP has detected this ionization signal at 200 million years after the Big Bang. We hope that the time history of the ionization will also help determine the nature of these first objects.
     
  9. Apr 10, 2004 #8

    wolram

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  10. Apr 11, 2004 #9
    Incidentally, the distance to the galaxy given in your second post is erroneous, the proper distance to the galaxy is 31.5 billions of ly.
    if the first stars formed 200 millions of years after big bang, I bet that the first galaxies formed 250 million of years after big bang.
     
  11. Apr 11, 2004 #10

    wolram

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    --------------------------------------------------------------------------
    well spoted, 100, 200, 300MYs sounds a long time, but then i
    think how old the earth is, and seems very short.
     
  12. Apr 13, 2004 #11

    Nereid

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    There's some healthy competition among observational astronomers, with the big facilities (HSTI, VLT, Keck, Gemini, ...) ever keen to proclaim new results. Even more breathless are the PR and marketing folk.

    Ahead of the spending of large sums of $, € (and some other currencies) on designing and building the forefront facilities, clear sets of scientific objectives are sought, and widely published; one of wolfram's links is to just such a list. Once the facilities pass their commissioning tests, scientific observations get under way. With the exception of 'director's discretionary allocation' and some time for TOO (targets of opportunity), time is allocated by a committee, which choses from (a usually large) set of proposals (I'm summarising; many details omitted, caveats apply). Time on telescopes, and with instruments (cameras, spectrometers, etc), is usually vastly oversubscribed - astronomers making proposals want far more time on the big beasties than is available. Proposals are usually called for in phases - committing the facility for ~12-18 months; in many cases the proposals (or at least summaries) are publicly available, as are the allocations (in general, not by a specific night).

    So, high-z objects have been the object ( :frown: ) of many, many proposals for time on the HST, VLT, Gemini, ... As the proposals are often justified (scientifically) in terms of testing current theory, it's no surprise that the HST, VLT, etc have been used to search for high-z (proto-)galaxies, nor is it any surprise how the astronomers would test whether an object found in a set of CCD images has a z of (x).

    Surveys etc. Crudely, astronomers do surveys or study specific objects. The former is some kind of general look at a lot of sky (or a selection of bits of sky), more or less to 'see what's there'. In the early days of a new window - e.g. the near and far IR, >100 MeV gamma - most work goes into surveys of one kind or the other (e.g. IRAS, Compton). Sometimes new technology permits a new survey of an otherwise well-studied window (e.g. SDSS).

    From what's found in a survey, detailed work can be done on specific objects, or classes of objects. For this work, the big beasties - HST, VLT, Keck, Gemini, etc - are used.

    Confirmation of just what the object Pelló et al. studied is may come from a dedicated HST observation (maybe), ditto for Keck (maybe), or the JWST (certainly). However, in terms of bang for the precious time on a telescope euro/buck, I'd guess finding and studying more objects, behind other Abell clusters, would be a better way to go. If for no other reason than to get some handle on how (a)typical this object actually is :smile:
     
  13. Apr 13, 2004 #12

    wolram

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    . With the exception of 'director's discretionary allocation' and some time for TOO (targets of opportunity), time is allocated by a committee, which choses from (a usually large) set of proposals
    --------------------------------------------------------------------------
    NEREID,
    can you say what has priority, does the commitee have a list of
    targets, observations ,that are fundamentaly more important than
    others?
     
  14. Apr 13, 2004 #13

    Nereid

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    GAIA, an ESA space-based project in an advanced stage of development, was designed to specifically address several fundamental questions in physics, including many further tests of General Relativity (not new effects really, rather significant improvements in accuracy and domain scope), and time-variation in G.

    While GAIA is principally a survey project, the successor to Hipparcos, its scientific objectives illustrate well how much effort goes into squeezing lots of science out of a new, expensive project.

    Time spent looking round the GAIA website (click on the links down the left-hand side) should be quite enjoyable, and give you a snapshot of how much further astronomy will go in the next decade or three ... transverse proper motion of Local Group galaxies! Who'd a thunk it :biggrin: :cool:
     
  15. Apr 17, 2004 #14
    I went to N.Wright calculator and discovered that an age of 250 millions of years correspond to a redshift of z=16. So I forecast that the maximum redshift that we will ever observe for a galaxy is z=16
     
  16. Apr 17, 2004 #15

    wolram

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    its a shame that astronomers have to compete with one another
    for scope time ,if i were GB TB or whatever president i would put
    at least as much time effort money in to it as war mongering.
     
  17. Apr 19, 2004 #16

    wolram

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    http://www.newscientist.com/news/news.jsp?id=ns99994729

    A small, faint galaxy may claim the title of the most distant object known - breaking a record that was set just two weeks ago.

    The new find appears to lie 13.2 billion light-years away from Earth and reveals what the earliest galaxies looked like.

    Light from this galaxy may have formed a mere 460 million years after the Big Bang, which formed the Universe 13.7 billion years ago, say its discoverers.
     
  18. Nov 11, 2004 #17
    Although a galaxy a z=10 has important implications, this 'detection' is near-IR spectroscopy, which is very difficult to reduce correctly due noise issues etc. You might be interested in these two papers (now both peer-reviewed and published/in press) which both fail to confirm any detection of the z=10 galaxy.
    A reanalysis of Pello's data: http://arxiv.org/abs/astro-ph/0407150
    Indepedent observations: http://arxiv.org/abs/astro-ph/0409485
     
  19. Nov 23, 2004 #18

    Nereid

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