New distant galaxy detected

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  • #1
Chronos
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A highly magnified candidate for a young galaxy seen when the Universe was 500 Myrs old
http://arxiv.org/abs/1204.2305

"... 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 object is the first z>9 candidate that is bright enough for detailed spectroscopic studies with JWST"

Spectroscopy of such an ancient galaxy would be very interesting.
 

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  • #2
phinds
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Very cool. Thanks for posting.

Do you know what they mean by "If the galaxy is indeed at such a large redshift, then its age is less than 200 Myr" ?

They start off saying it is probably 500 million years old (dating from the singularity) and SEEM to use "Myr" with that, so I'm confused by the later use of "200 Myr"
 
  • #3
Chronos
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Based on existing models, the earliest galaxies should not develop until around 300 million years after the BB.
 
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Very cool. Thanks for posting.

Do you know what they mean by "If the galaxy is indeed at such a large redshift, then its age is less than 200 Myr" ?

They start off saying it is probably 500 million years old (dating from the singularity) and SEEM to use "Myr" with that, so I'm confused by the later use of "200 Myr"
In the paper they say
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-2 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
I think what they're saying is that the image they have is of a galaxy which is 'now' 500 million years old and which first formed at 200 million yrs.
 
  • #5
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In the paper they say

..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
I think what they're saying is that the image they have is of a galaxy which is 'now' 500 million years old and which first formed at 200 million yrs.
If the light was emitted at 490Myr and they have constrained the age to be less than 200Myr from the spectrum, they deduce its formation would have been at a cosmic age of at least 290 Myr. That implies its formation was at z<14 and implies we will be able to observe the period of formation with JWST which is designed to work to z=15 or higher.
 
  • #6
Chronos
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Spectroscopic data will be difficult to acquire at z~14, even with JWST, without gravitational lensing. This little gal offers a unique [so far] opportunity to probe the composition of the universe near z~10.
 

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