'Dropouts' pinpoint earliest galaxies
November 6, 2009
This is a composite of false color images of the galaxies found at the early epoch around 800 million years after the Big Bang. The upper left panel presents the galaxy confirmed in the 787 million year old universe. These galaxies are in the Subaru Deep Field. Credit: These images are created by M. Ouchi et al., which are the reproduction of Figure 3 in the Astrophysical Journal December 2009 issue.
Astronomers, conducting the broadest survey to date of galaxies from about 800 million years after the Big Bang, have found 22 early galaxies and confirmed the age of one by its characteristic hydrogen signature at 787 million years post Big Bang. The finding is the first age-confirmation of a so-called dropout galaxy at that distant time and pinpoints when an era called the reionization epoch likely began. The research will be published in a December issue of the Astrophysical Journal.
With recent technological advancements, such as the Wide-Field Camera 3 on the Hubble Space Telescope, there has been an explosion of research of the reionization period, the farthest back in time that astronomers can observe.
The Big Bang, 13.7 billion years ago, created a hot, murky universe. Some 400,000 years later, temperatures cooled, electrons and protons joined to form neutral hydrogen, and the murk cleared. Some time before 1 billion years after the Big Bang, neutral hydrogen began to form stars in the first galaxies, which radiated energy and changed the hydrogen back to being ionized. Although not the thick plasma soup of the earlier period just after the Big Bang, this star formation started the reionization epoch. Astronomers know that this era ended about 1 billion years after the Big Bang, but when it began has eluded them and intrigued researchers like lead author Masami Ouchi of the Carnegie Observatories.
The U.S. and Japanese team led by Ouchi used a technique for finding these extremely distant galaxies. "We look for 'dropout' galaxies," explained Ouchi. "We use progressively redder filters that reveal increasing wavelengths of light and watch which galaxies disappear from or 'dropout' of images made using those filters. Older, more distant galaxies 'dropout' of progressively redder filters and the specific wavelengths can tell us the galaxies' distance and age. What makes this study different is that we surveyed an area that is over 100 times larger than previous ones and, as a result, had a larger sample of early galaxies (22) than past surveys. Plus, we were able to confirm one galaxy's age," he continued. "Since all the galaxies were found using the same dropout technique, they are likely to be the same age."
Ouchi's team was able to conduct such a large survey because they used a custom-made, super-red filter and other unique technological advancements in red sensitivity on the wide-field camera of the 8.3-meter Subaru Telescope. They made their observations from 2006 to 2009 in the Subaru Deep Field and Great Observatories Origins Deep Survey North field. They then compared their observations with data gathered in other studies.
Astronomers have wondered whether the universe underwent reionization instantaneously or gradually over time, but more importantly, they have tried to isolate when the universe began reionization. Galaxy density and brightness measurements are key to calculating star-formation rates, which tell a lot about what happened when. The astronomers looked at star-formation rates and the rate at which hydrogen was ionized.
Using data from their study and others, they determined that the star-formation rates were dramatically lower from 800 millions years to about one billion years after the Big Bang, then thereafter. Accordingly, they calculated that the rate of ionization would be very slow during this early time, because of this low star-formation rate.
"We were really surprised that the rate of ionization seems so low, which would constitute a contradiction with the claim of NASA's WMAP satellite. It concluded that reionization started no later than 600 million years after the Big Bang," remarked Ouchi. "We think this riddle might be explained by more efficient ionizing photon production rates in early galaxies. The formation of massive stars may have been much more vigorous then than in today's galaxies. Fewer, massive stars produce more ionizing photons than many smaller stars," he explained.
Source: Carnegie Institution
11 hours ago
Agreed, and here is precisely the problem with the gassy Big Bang, a massive galaxy supposedly 800 million years old, HUDF-JD2. It has the appearance of any galaxy that is billions of years older but shows up in a place galaxies that size are not supposed to be. The alternative hypothesis is the "orbiting universe", a universe where the movements of all bodies are in orbit about another larger body (including the galaxies), this would account for all galactic blue shift as well as galactic redshift.
Isn't that the Ptolemaic epicycle model of ancient fame?
You say these far-off well-developed galaxies are on the rim of the observable region of the universe and give us a glimpse into the non-observable part of the infinite universe?
You're completely ignoring spacial energy denisty, in addition to gravitic peturbation.
The big bang theory looks bunk until you understand all the intricate factors of it.
You say these far-off well-developed galaxies are on the rim of the observable region of the universe and give us a glimpse into the non-observable part of the infinite universe?
Yes the limit of what we see, the universe is eternal and infinit I'm shure of that, this part of universe is nothing compare to what is the universe realy is.
There are none.
Of course there are. One example:
http://wwwphy.pri...inh/npr/
It is the law of "Conservation of Energy"
After parsing the press release and re-reading the paper I linked above, it appears this is indeed an extension of the work published in the 2006 paper. The current PI, Masami Ouchi, appears as a coauthor on the 2006 paper, which mentions in its summary that new more sensitive observations of the Subaru Deep Field would be conducted using newer red sensitive CCDs in the SuprimeCam on the 8.2m Subaru (not 8.3m as noted in Carnegie and Eurekalert press releases). In the 2006 paper, only two 'Lyman-alpha Emitters' were positively detected using the 'dropout' technique (IOK-1 & IOK-2), but only the former was detected spectroscopically. Now 22 LAEs have been detected in the Subaru Deep Field.
Here's another http://tinyurl.com/ye337wo
In paragraph 2 the writer said "Astronomers know.."
Sadly neither Astronomers or anyone else "knows".
At best they theorise.
And as so many respondents have said, "the big bang theory is running low on gas"
One thought that intrigues me is that the estimated period of time since the big bang is remarkably close to the limits of the visible universe, our visibility horizon
Perhaps all the missing matter is simply "out of sight".
Whenever we communicate we rely on a lot of conventions. In astrophysical contexts conventionally the standard model is assumed. Only if you want to refer to non-standard theories you'll have to mention them.
There are indeed theories which essentially tell us exactly this kind of thing.