For 1 brief shining minute later the 2015 detection of gravitational waves from colliding dark holes, astronomers held out promise that the universe's mysterious night affair mightiness consist of a plenitude of dark holes sprinkled throughout the universe. University of California, Berkeley, physicists convey dashed those hopes.
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| A supernova (bright spot at lower left) together with its host galaxy (upper center), equally they would appear if gravitationally lensed by an intervening dark hole (center). The gravitational patch of the dark hole distorts together with magnifies the ikon together with makes both the galaxy together with the supernova smooth brighter. Gravitationally magnified supernovas would occur rather frequently if dark holes were the dominant shape of affair inwards the universe. The lack of such findings tin hold out used to prepare limits on the majority together with abundance of dark holes [Credit: Miguel Zumalacarregui/UC Berkeley] |
The results suggest that none of the universe's night affair consists of heavy dark holes, or whatsoever similar object, including massive compact halo objects, so-called MACHOs.
Dark affair is 1 of astronomy's most embarrassing conundrums: despite comprising 84.5 per centum of the affair inwards the universe, no 1 tin uncovering it. Proposed night affair candidates bridge nearly xc orders of magnitude inwards mass, from ultralight particles similar axions to MACHOs.
Several theorists convey proposed scenarios inwards which at that spot are multiple types of night matter. But if night affair consists of several unrelated components, each would require a dissimilar explanation for its origin, which makes the models real complex.
"I tin imagine it beingness 2 types of dark holes, real heavy together with real lite ones, or dark holes together with novel particles. But inwards that illustration 1 of the components is orders of magnitude heavier than the other, together with they postulate to hold out produced inwards comparable abundance. We would hold out going from something astrophysical to something that is genuinely microscopic, perchance fifty-fifty the lightest thing inwards the universe, together with that would hold out real hard to explain," said Pb writer Miguel Zumalacárregui, a Marie Curie Global Fellow at the Berkeley Center for Cosmological Physics.
An as-yet unpublished reanalysis yesteryear the same squad using an updated listing of 1,048 supernovas cuts the bound inwards half, to a maximum of nigh 23 percent, farther slamming the door on the night matter-black hole proposal.
"We are dorsum to the measure discussions. What is night matter? Indeed, nosotros are running out of skillful options," said Uroš Seljak, a UC Berkeley professor of physics together with astronomy together with BCCP co-director. "This is a challenge for futurity generations."
The analysis is detailed inwards a newspaper published this calendar week inwards the mag Physical Review Letters.
Dark affair lensing
Their conclusions are based on the fact that an unseen population of primordial dark holes, or whatsoever massive compact object, would gravitationally curvature together with magnify lite from distant objects on its means to Earth. Therefore, gravitational lensing should deport upon the lite from distant Type Ia supernovas. These are the exploding stars that scientists convey used equally measure brightness sources to mensurate cosmic distances together with document the expansion of the universe.
Zumalacárregui conducted a complex statistical analysis of information on the brightness together with distance supernovas catalogued inwards 2 compilations -- 580 inwards the Union together with 740 inwards the articulation light-curve analysis (JLA) catalogs -- together with concluded that 8 should hold out brighter yesteryear a few tenths of a per centum than predicted based on observations of how these supernovas brighten together with fade over time. No such brightening has been detected.
Other researchers convey performed similar merely simpler analyses that yielded inconclusive results. But Zumalacárregui incorporated the precise probability of seeing all magnifications, from pocket-size to huge, equally good equally uncertainties inwards brightness together with distance of each supernova. Even for low-mass dark holes -- those 1 per centum the majority of the Sun -- at that spot should hold out roughly highly magnified distant supernovas, he said, merely at that spot are none.
"You cannot encounter this lawsuit on 1 supernova, merely when you lot position them all together together with practise a total Bayesian analysis you lot start putting real potent constraints on the night matter, because each supernova counts together with you lot convey thence many of them," Zumalacárregui said. The to a greater extent than supernovas included inwards the analysis, together with the farther away they are, the tighter the constraints. Data on 1,048 brilliant supernovas from the Pantheon catalog provided an fifty-fifty lower upper bound -- 23 per centum -- than the newly published analysis.
Seljak published a newspaper proposing this type of analysis inwards the belatedly 1990s, merely when involvement shifted from looking for big objects, MACHOs, to looking for cardinal particles, inwards exceptional weakly interacting massive particles, or WIMPs, follow-up plans roughshod yesteryear the wayside. By then, many experiments had excluded most masses together with types of MACHOs, leaving lilliputian promise of discovering such objects.
At the time, too, solely a pocket-size number of distant Type Ia supernovas had been discovered together with their distances measured.
Only later the LIGO observations brought upward the number 1 time to a greater extent than did Seljak together with Zumalacárregui embark on the complicated analysis to create upward one's heed the limits on night matter.
"What was intriguing is that the masses of the dark holes inwards the LIGO lawsuit were correct where dark holes had non even thence been excluded equally night matter," Seljak said. "That was an interesting coincidence that got everyone excited. But it was a coincidence."
Author: Robert Sanders | Source: University of California - Berkeley [October 03, 2018]
Sumber http://archaeologynewsnetwork.blogspot.com
Several theorists convey proposed scenarios inwards which at that spot are multiple types of night matter. But if night affair consists of several unrelated components, each would require a dissimilar explanation for its origin, which makes the models real complex.
"I tin imagine it beingness 2 types of dark holes, real heavy together with real lite ones, or dark holes together with novel particles. But inwards that illustration 1 of the components is orders of magnitude heavier than the other, together with they postulate to hold out produced inwards comparable abundance. We would hold out going from something astrophysical to something that is genuinely microscopic, perchance fifty-fifty the lightest thing inwards the universe, together with that would hold out real hard to explain," said Pb writer Miguel Zumalacárregui, a Marie Curie Global Fellow at the Berkeley Center for Cosmological Physics.
An as-yet unpublished reanalysis yesteryear the same squad using an updated listing of 1,048 supernovas cuts the bound inwards half, to a maximum of nigh 23 percent, farther slamming the door on the night matter-black hole proposal.
"We are dorsum to the measure discussions. What is night matter? Indeed, nosotros are running out of skillful options," said Uroš Seljak, a UC Berkeley professor of physics together with astronomy together with BCCP co-director. "This is a challenge for futurity generations."
The analysis is detailed inwards a newspaper published this calendar week inwards the mag Physical Review Letters.
Dark affair lensing
Their conclusions are based on the fact that an unseen population of primordial dark holes, or whatsoever massive compact object, would gravitationally curvature together with magnify lite from distant objects on its means to Earth. Therefore, gravitational lensing should deport upon the lite from distant Type Ia supernovas. These are the exploding stars that scientists convey used equally measure brightness sources to mensurate cosmic distances together with document the expansion of the universe.
Zumalacárregui conducted a complex statistical analysis of information on the brightness together with distance supernovas catalogued inwards 2 compilations -- 580 inwards the Union together with 740 inwards the articulation light-curve analysis (JLA) catalogs -- together with concluded that 8 should hold out brighter yesteryear a few tenths of a per centum than predicted based on observations of how these supernovas brighten together with fade over time. No such brightening has been detected.
Other researchers convey performed similar merely simpler analyses that yielded inconclusive results. But Zumalacárregui incorporated the precise probability of seeing all magnifications, from pocket-size to huge, equally good equally uncertainties inwards brightness together with distance of each supernova. Even for low-mass dark holes -- those 1 per centum the majority of the Sun -- at that spot should hold out roughly highly magnified distant supernovas, he said, merely at that spot are none.
"You cannot encounter this lawsuit on 1 supernova, merely when you lot position them all together together with practise a total Bayesian analysis you lot start putting real potent constraints on the night matter, because each supernova counts together with you lot convey thence many of them," Zumalacárregui said. The to a greater extent than supernovas included inwards the analysis, together with the farther away they are, the tighter the constraints. Data on 1,048 brilliant supernovas from the Pantheon catalog provided an fifty-fifty lower upper bound -- 23 per centum -- than the newly published analysis.
Seljak published a newspaper proposing this type of analysis inwards the belatedly 1990s, merely when involvement shifted from looking for big objects, MACHOs, to looking for cardinal particles, inwards exceptional weakly interacting massive particles, or WIMPs, follow-up plans roughshod yesteryear the wayside. By then, many experiments had excluded most masses together with types of MACHOs, leaving lilliputian promise of discovering such objects.
At the time, too, solely a pocket-size number of distant Type Ia supernovas had been discovered together with their distances measured.
Only later the LIGO observations brought upward the number 1 time to a greater extent than did Seljak together with Zumalacárregui embark on the complicated analysis to create upward one's heed the limits on night matter.
"What was intriguing is that the masses of the dark holes inwards the LIGO lawsuit were correct where dark holes had non even thence been excluded equally night matter," Seljak said. "That was an interesting coincidence that got everyone excited. But it was a coincidence."
Author: Robert Sanders | Source: University of California - Berkeley [October 03, 2018]
Sumber http://archaeologynewsnetwork.blogspot.com
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