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ToSeek
2003-Mar-26, 08:29 PM
Most distant galaxy ever observed (http://www.subaru.naoj.org/Latestnews/200303/SDF/index_e.html) (and they're still looking)

I found the approach is interesting: they've figured out the wavelength of light distant galaxies would be emitting and are filtering and searching on that basis. Looks as if there will be more news to come along these lines.

Hale_Bopp
2003-Mar-26, 11:41 PM
This is similar to how the Sloan Digital Sky Survey finds its distant quasars. The SDSS images through five filters. The i filter is centered around 7700 Angstroms and the z filter is around 9200 Angstroms if memory serves. Very high redshift quasars show up in the z filter but not the i filter due to the redshift of the Hydrogen alpha line. These are called i drop outs. Some of them turn out to be cool methane dwarfs, but they have found several quasars above z = 6.

I like the fact that they have spectra. That previous galaxy record holder was criticized when it was published since they based the redshift on a single spectral line.

Note how far into the infrared the Halpha line is already moving. To get more distant quasars and galaxies, infrared instruments will be needed. 2MASS didn't really go deep enough...does anyone know how deep SOFIA will be able to get? I know the Webb Space Telescope will be optimized for this, but it won't launch until late this decade at the earliest.

Rob

The Bad Astronomer
2003-Mar-27, 12:32 AM
I think you mean Lyman alpha (1216 Angstroms), not H-alpha (6563). A z=6 means 1216 * 7 =~ 8500 Angstroms.

Hale_Bopp
2003-Mar-27, 12:40 AM
My bad...I know the transition, but forget the names sometimes! Of course, that is the Lyman alpha line...Halpha is the Balmer line in the visible portion of the spectrum.


Rob

Charlie in Dayton
2003-Mar-27, 03:35 AM
Hmmm...lotza flyin' saucers and space angels in them large/larger photos...any idea why
EVERY FREAKIN' ONE OF 'EM

is dead center in the image of something bright?