by drollere » Wed Dec 09, 2009 9:50 pm
i have two rather technical questions about deep space imagery in general.
* galactic density. as we image galaxies farther back in time, we see the galactic distribution during those eras. presumably, at the distance of the microwave background, we see no galaxies, because they had not formed yet. but if galaxies did not form simultaneously, then we should see either (1) more/fewer galaxies at different time periods, (2) fewer "late evolving" elliptical galaxies earlier in time, up to the point of the first wave of galactic formation, and which point elliptical galaxies should not be visible. do we see any distance related differences in galactic distribution, either as density of galaxies of any kind (averaged over the entire extragalactic sky) or density variation in the type of galaxies?
* optical correction. going further back in time means that the same area of sky images a smaller and smaller volume of space. (if it were possible to see the singularity, then a single point would cover the entire celestial sphere.) therefore the procedure of counting galaxies or estimating the size of microwave anomalies requires a time-variable metric of angular size. is that generally a problem recognized in interpreting these distant images? does it produce an enlargement of the galactic image? how otherwise is it addressed/handled/corrected when interpreting these deep space images?
i have two rather technical questions about deep space imagery in general.
* galactic density. as we image galaxies farther back in time, we see the galactic distribution during those eras. presumably, at the distance of the microwave background, we see no galaxies, because they had not formed yet. but if galaxies did not form simultaneously, then we should see either (1) more/fewer galaxies at different time periods, (2) fewer "late evolving" elliptical galaxies earlier in time, up to the point of the first wave of galactic formation, and which point elliptical galaxies should not be visible. do we see any distance related differences in galactic distribution, either as density of galaxies of any kind (averaged over the entire extragalactic sky) or density variation in the type of galaxies?
* optical correction. going further back in time means that the same area of sky images a smaller and smaller volume of space. (if it were possible to see the singularity, then a single point would cover the entire celestial sphere.) therefore the procedure of counting galaxies or estimating the size of microwave anomalies requires a time-variable metric of angular size. is that generally a problem recognized in interpreting these distant images? does it produce an enlargement of the galactic image? how otherwise is it addressed/handled/corrected when interpreting these deep space images?