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No WIMP Annihilation Observed In SMC
http://arxiv.org/abs/1603.00965
Caputo et al SMC is identified as a "natural" place to search for indirect WIMP DM annihilation. Six years of Fermi-LAT data used. "no signal" Agrees no signal and with stronger limits for LMC (and MWG center?) RLO http://www3.amherst.edu/~rloldershaw |
#2
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No WIMP Annihilation Observed In SMC
On Saturday, March 5, 2016 at 4:33:57 AM UTC-5, Robert L. Oldershaw wrote:
http://arxiv.org/abs/1603.00965 ..... Six years of Fermi-LAT data used. "no signal" Agrees no signal and with stronger limits for LMC (and MWG center?) Thanks for quoting out of context. More context from the abstract reveals, "we found that the SMC was well described by standard astrophysical sources, and no signal from dark matter annihilation was detected." I.e. the Fermi analysis was not sensitive enough to detect to detect a signal, which is different than claiming that Fermi detected a lack of signal (which was not claimed). And to be clear, there *IS* a claimed dark matter signal by Fermi from the Milky Way galactic center. CM |
#3
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No WIMP Annihilation Observed In SMC
On Tuesday, March 8, 2016 at 3:15:49 AM UTC-5, Craig Markwardt wrote:
And to be clear, there *IS* a claimed dark matter signal by Fermi from the Milky Way galactic center. Well, with all due respect, the FERMI group disagrees with you, if you believe that the "claim" has any solid *empirical* basis. See for example: http://arxiv.org/abs/1501.05464 . Also did you see the thread I started entitled "WIMPs AWOL Again", wherein I offered some additional evidence published in PRL. You might be interested in the following important contribution of the authors to this area of research: http://arxiv.org/abs/1506.05104 . [Mod. note: reformatted, comment addressed to moderators removed -- please do not put comments addressed to moderators in your posts -- mjh] RLO http://www3.amherst.edu/~rloldershaw |
#4
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No WIMP Annihilation Observed In SMC
On Wednesday, March 9, 2016 at 3:17:32 AM UTC-5, Robert L. Oldershaw wrote:
On Tuesday, March 8, 2016 at 3:15:49 AM UTC-5, Craig Markwardt wrote: And to be clear, there *IS* a claimed dark matter signal by Fermi from the Milky Way galactic center. Well, with all due respect, the FERMI group disagrees with you, ... Fair enough. So you now understand the original paper's lack of detection (i.e. an upper limit), is different than your claim of "no signal?" The difference is in the statistics and in the expectations of the relevant scientific models. CM |
#5
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No WIMP Annihilation Observed In SMC
On Friday, March 11, 2016 at 3:11:18 AM UTC-5, Craig Markwardt wrote:
Fair enough. So you now understand the original paper's lack of detection (i.e. an upper limit), is different than your claim of "no signal?" The difference is in the statistics and in the expectations of the relevant scientific models. Well Craig, in scientific discussions would it not be rigorously obvious that the curt phrase "no signal" comes with the inherent implication that the any conclusion applies to this experiment, and at this level of sensitivity? It is extremely rare in science when some phenomena can be ruled out absolutely and for all time. This is especially true when the result is a NEGATIVE result. Please correct me if I am wrong. RLO ? http://www3.amherst.edu/~rloldershaw |
#6
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No WIMP Annihilation Observed In SMC
On Sunday, March 13, 2016 at 5:17:49 AM UTC-4, Robert L. Oldershaw wrote:
On Friday, March 11, 2016 at 3:11:18 AM UTC-5, Craig Markwardt wrote: Fair enough. So you now understand the original paper's lack of detection (i.e. an upper limit), is different than your claim of "no signal?" The difference is in the statistics and in the expectations of the relevant scientific models. Well Craig, in scientific discussions would it not be rigorously obvious that the curt phrase "no signal" comes with the inherent implication that the any conclusion applies to this experiment, and at this level of sensitivity? It's best not to assume the obvious in conversations with you. So if you had read the paper, it should be obvious that the detection limit established by the observations... wouldn't have been expected to detect relevant dark matter signals. So why raise this paper as interesting? CM |
#7
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No WIMP Annihilation Observed In SMC
On Thursday, March 17, 2016 at 12:22:00 PM UTC-4, Craig Markwardt wrote:
It's best not to assume the obvious in conversations with you. So if you had read the paper, it should be obvious that the detection limit established by the observations... wouldn't have been expected to detect relevant dark matter signals. So why raise this paper as interesting? I will let your false assumption that I had not read the paper pass, and just point out that the authors of that paper unequivocally stated that they thought it was important to look for a DM annihilation signal from the SMC for good astrophysical reasons. They expected that they might find one, but they did not. Are you claiming that the authors, reviewers and the editor of the journal that accepted it were all engaging in promoting unnecessary and misleading research? Please explain yourself. RLO http://www3.amherst.edu/~rloldershaw |
#8
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No WIMP Annihilation Observed In SMC
Science magazine today:
http://science.sciencemag.org/conten.../1376.full.pdf "It's crunch time", says Rocky Kolb, a theorist at the University of Chicago (UC) in Illinois, comparing the WIMP quest to a football game. "We're in the second half, maybe the fourth quarter. We haven't scored." Elena Aprile, an experimentalist at Columbia University and leader of the XENON team, says the new detector has a real shot at discovering WIMPs: "They could be right around the corner." But, she adds, "We're perhaps losing faith in the sense that we're not sure whether 1 ton or even 10 tons will be enough to see anything." Other dark matter researchers share her concerns. A few years ago, when the biggest WIMP detector weighed a few kilograms, most thought that a 1-ton experiment would either find WIMPs or stick a dagger in the idea. But generations of ever bigger detectors have come up empty, and physicists are rethinking the argument for WIMPs and what it might take to find them. They have bigger detectors in the works and are laying plans for the ultimate WIMP detector. But even avid dark matter hunters aren't sure that the giant detector is worth pursuing. [snip] ..... physicists are anxious about its prospects. Their main concern is that in 6 years of running, the LHC has found no evidence of supersymmetry - the foundation of the WIMP model. It's not too late, as until last year the LHC ran at only half energy. Still, "the 800-pound gorilla in the room is the lack of any sign of supersymmetry coming from the LHC," says Juan Collar, an experimentalist at UC. To hedge their bets, dark matter researchers are working on even bigger detectors. XENON1T is designed so that in 2 years it can be expanded to create XENONnT, which would hold 7.5 metric tons of xenon. And researchers with LUX are building a detector called LZ that should hold 10 metric tons of xenon and would come on line in 2019. |
#9
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No WIMP Annihilation Observed In SMC
On 3/30/2016 9:22 AM, jacobnavia wrote:
... .... physicists are anxious about its prospects. Their main concern is that in 6 years of running, the LHC has found no evidence of supersymmetry - the foundation of the WIMP model. If dark matter is not super-symmetric particles, can it still be one of the following, or are those also ruled out already? 1) Axions (say with 100ueV mass?) 2) Heavy Sterile neutrinos? 3) Primordial black holes? -- Jos |
#10
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No WIMP Annihilation Observed In SMC
On Wednesday, March 30, 2016 at 3:23:29 AM UTC-4, jacobnavia wrote:
Science magazine today: http://science.sciencemag.org/conten.../1376.full.pdf "It's crunch time", says Rocky Kolb, a theorist at the University of Chicago (UC) in Illinois, comparing the WIMP quest to a football game. "We're in the second half, maybe the fourth quarter. We haven't scored." Elena Aprile, an experimentalist at Columbia University and leader of the XENON team, says the new detector has a real shot at discovering WIMPs: "They could be right around the corner." But, she adds, "We're perhaps losing faith in the sense that we're not sure whether 1 ton or even 10 tons will be enough to see anything." Note that Dr. Aprile's real and clearly stated concern is whether the detectors, existing and planned, "will be big enough". There is a giant difference between losing confidence in the general WIMP hypothesis, and losing confidence in our ability and/or willingness to build something big/expensive enough to detect what "must" exist. Really, it is the same with the "sparticles" of SUSY, or WIMPs or "strings". The proponents of these hypotheses firmly believe in their existence and will assure us that they are to be found just over then next energy/ detector size hill, or the next, or the next. There is only one way the WIMP game can end, and that is if the dark matter turns out to be something else entirely and the evidence is undeniable. If a genie offered me three wishes, I would say tell me what the dark matter is and I'll forgo the other two wishes. RLO ttp://www3.amherst.edu/~rloldershaw |
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