Rest easy Harry
The article itself is confused. Whoever wrote the article had its premise backward. On Sat, Jul 12, 2014 at 10:27 PM, H Veeder <[email protected]> wrote: > > > > On Sat, Jul 12, 2014 at 7:21 PM, Axil Axil <[email protected]> wrote: > >> Regarding the title: 400 percent less light in universe than predicted >> >> This article and the title are not well written. >> >> The title should read that there are missing light *sources* not XUV >> light. That is, the is more light produced than there are light sources. >> >> [Snip] >> >> “It’s as if you’re in a big, brightly lit room, but you look around and >> see only a few 40-watt lightbulbs,” >> >> [EndSnip] >> >> There are less 40-watt light bulbs than would be expected for the amount >> of XUV light produced. These bulbs are light sources. There is too much >> light than the light sources can produce. >> >> >> > > Oh, my mistake, so the subject header should say "400 percent more light > in universe than predicted" > > Harry > > > >> On Sat, Jul 12, 2014 at 7:03 PM, H Veeder <[email protected]> wrote: >> >>> CU-Boulder instrument onboard Hubble reveals the universe is ‘missing’ >>> light >>> >>> http://tinyurl.com/qzs4rjo >>> >>> July 9, 2014 • >>> >>> Something is amiss in the universe. There appears to be an enormous >>> deficit of ultraviolet light in the cosmic budget. >>> >>> Observations made by the Cosmic Origins Spectrograph, a $70 million >>> instrument designed by the University of Colorado Boulder and installed on >>> the Hubble Space Telescope, have revealed that the universe is “missing” a >>> large amount of light. >>> >>> “It’s as if you’re in a big, brightly lit room, but you look around and >>> see only a few 40-watt lightbulbs,” said the Carnegie Institution for >>> Science’s Juna Kollmeier, lead author of a new study on the missing light >>> published in The Astrophysical Journal Letters. “Where is all that light >>> coming from? It’s missing from our census.” >>> >>> The research team—which includes Benjamin Oppenheimer and Charles >>> Danforth of CU-Boulder’s Center for Astrophysics and Space >>> Astronomy—analyzed the tendrils of hydrogen that bridge the vast reaches of >>> empty space between galaxies. When hydrogen atoms are struck by highly >>> energetic ultraviolet light, they are transformed from electrically neutral >>> atoms to charged ions. >>> >>> The astronomers were surprised when they found far more hydrogen ions >>> than could be explained with the known ultraviolet light in the universe, >>> which comes primarily from quasars. The difference is a stunning 400 >>> percent. >>> >>> Strangely, this mismatch only appears in the nearby, relatively >>> well-studied cosmos. When telescopes focus on galaxies billions of light >>> years away—which shows astronomers what was happening when the universe was >>> young—everything seems to add up. The fact that the accounting of light >>> needed to ionize hydrogen works in the early universe but falls apart >>> locally has scientists puzzled. >>> >>> The mismatch emerged from comparing supercomputer simulations of >>> intergalactic gas to the most recent analysis of observations from the >>> Cosmic Origins Spectrograph. >>> >>> “The simulations fit the data beautifully in the early universe, and >>> they fit the local data beautifully if we’re allowed to assume that this >>> extra light is really there,” said CU-Boulder’s Oppenheimer. “It’s possible >>> the simulations do not reflect reality, which by itself would be a >>> surprise, because intergalactic hydrogen is the component of the universe >>> that we think we understand the best.” >>> >>> The type of light that is energetic enough to turn neutral hydrogen into >>> hydrogen ions is called “ionizing photons” and is known to come from only >>> two sources in the universe: quasars, which are powered by hot gas falling >>> onto supermassive black holes over a million times the mass of the sun, and >>> the hottest young stars. Observations indicate that the ionizing photons >>> from young stars are almost always absorbed by gas in their host galaxy, so >>> they never escape to affect intergalactic hydrogen. But the number of known >>> quasars is far lower than needed to produce the amount of light necessary >>> to create the quantity of hydrogen ions measured by the research team. >>> >>> >>> “If we count up the known sources of ultraviolet ionizing photons, we >>> come up five times too short,” Oppenheimer said. “We are missing 80 percent >>> of the ionizing photons, and the question is where are they coming from? >>> The most fascinating possibility is that an exotic new source, not quasars >>> or galaxies, is responsible for the missing photons.” >>> >>> For example, the mysterious dark matter, which holds galaxies together >>> but has never been seen directly, could itself decay and ultimately be >>> responsible for this extra light. >>> >>> “The great thing about a 400 percent discrepancy is that you know >>> something is really wrong,” said co-author David Weinberg of Ohio State >>> University. “We still don't know for sure what it is, but at least one >>> thing we thought we knew about the present day universe isn’t true.” >>> >>> Other co-authors on the study are Francesco Haardt of the Università >>> dell’Insubria, Romeel Davé of the University of the Western Cape, Mark >>> Fardal of University of Massachusetts Amherst, Piero Madau of the >>> University of California, Santa Cruz, Amanda Ford of the University of >>> Arizona, Molly Peeples of the Space Telescope Science Institute, and Joseph >>> McEwen of Ohio State University. >>> >>> The study was funded in part by NASA, the National Science Foundation >>> and the Ahmanson Foundation. >>> >> >> >
