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#1
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'Dragons' of the Gamms-Ray Sky
Be sure to check this out!
http://www.sciencedaily.com/releases...0302162505.htm It has long been assumed that the diffuse Gamma-Ray background was dominated by active galaxies like blazars, quasars, Seyferts, etc. Now comes a dramatic result from the Fermi team that appears to reject that assumption, and leaves a very important question in its place. The Fermi team reports ( http://arxiv.org/PS_cache/arxiv/pdf/...002.4415v1.pdf ) that only about 1/3 of the diffuse Gamma-ray background comes from active galaxies. That leaves 2/3 of the background being produced by unknown entities. Two possible explanations for the unknown source population are as follows. [Mod. note: to save time and electrons, let me be the first to point out that there are probably more than two in total -- mjh] (1) The radiation could be generated by hypothetical annihilations of hypothetical WIMPS (good luck with that one). (2) Alternatively, contrary to current assumptions, there could be a roughly isotropic distribution of stellar-mass black holes in the MWG halo that emit very high energy jets of particles which, in turn, generate Gamma-rays. In this scenario, all galactic haloes would contribute to the Gamma-ray background too. Note that a large populaton of stellar-mass black holes in more quiescent states would be a nice candidate for the Long Duration Radio Transients and the anomalous radio background discovered in the ARCADE observations. Perhaps nature is sending us many hints: X-ray Ridge discrete sources, LDRTs, RRATs, Gamma-ray background, microlensing-detected MACHOs, Gamma-ray burst sources, pulsars, quiescent neutron stars, compact central objects in SN remnants? One general class of stellar-mass ultracompact objects with masses primarily in the 10^-4 to 2.0 solar mass range would explain quite a number of enigmatic results. RLO www.amherst.edu/~rloldershaw |
#2
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'Dragons' of the Gamms-Ray Sky
In article , "Robert L.
Oldershaw" writes: (2) Alternatively, contrary to current assumptions, there could be a roughly isotropic distribution of stellar-mass black holes in the MWG halo that emit very high energy jets of particles which, in turn, generate Gamma-rays. In this scenario, all galactic haloes would contribute to the Gamma-ray background too. Why should anyone believe this if no TESTABLE PREDICTION indicating such radiation was made BEFORE the observation? One can always take any observation and say that, maybe, contrary to current assumptions, some object is responsible for it. But that's not science. Maybe there are angels whose moving wings radiate gamma rays. That's an explanation in the same league. One general class of stellar-mass ultracompact objects with masses primarily in the 10^-4 to 2.0 solar mass range would explain quite a number of enigmatic results. Perhaps, but it has been RULED OUT due to the lack of a PREDICTED signature in QSO light curves. |
#3
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'Dragons' of the Gamma-Ray Sky
Robert L. Oldershaw wrote:
So why do so many astrophysicists assume the dark matter is composed of WIMPs, or even more exotic particles, while very few astrophysicists entertain the possibility that the observed stellar- mass ultracompacts might be the proverbial tip of the dark matter iceberg? Which part of Phillip's "ruled out by evidence" do you have trouble understanding? He's told you that at least twice. You keep trying to sneak your "dark stars as the dark matter" in one way or another, but the evidence has already eliminated them. This gets tedious. Could you find another hobby? xanthian. |
#4
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'Dragons' of the Gamma-Ray Sky
"Kent Paul Dolan" wrote in message
... Robert L. Oldershaw wrote: So why do so many astrophysicists assume the dark matter is composed of WIMPs, or even more exotic particles, while very few astrophysicists entertain the possibility that the observed stellar- mass ultracompacts might be the proverbial tip of the dark matter iceberg? Which part of Phillip's "ruled out by evidence" do you have trouble understanding? He's told you that at least twice. You keep trying to sneak your "dark stars as the dark matter" in one way or another, but the evidence has already eliminated them. This gets tedious. Could you find another hobby? xanthian. can you provide links to this evidence? a curious amateur |
#5
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'Dragons' of the Gamms-Ray Sky
On 3/8/10 3:13 PM, Robert L. Oldershaw wrote:
The Fermi team reports ( http://arxiv.org/PS_cache/arxiv/pdf/...002.4415v1.pdf ) that only about 1/3 of the diffuse Gamma-ray background comes from active galaxies. That leaves 2/3 of the background being produced by unknown entities. A large question is whether the peak at 56 Mev (figure 4) EGRET (Sreekumar et al. 1997) EGRET (Strong et al. 2004) is confirmed by further data analysis extending Fermi (Abdo et al. 2009) (figure 4) to that 56 Mev peak range. Why the peak? and why the near constant log slope with increased energy? This is a 'noisy' area of the FERMI platform and will take more data analysis time. I think the answer is extremely fundamental. Richard D. Saam |
#6
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'Dragons' of the Gamma-Ray Sky
In article , "Robert L.
Oldershaw" writes: So why do so many astrophysicists assume the dark matter is composed of WIMPs, or even more exotic particles, while very few astrophysicists entertain the possibility that the observed stellar- mass ultracompacts might be the proverbial tip of the dark matter iceberg? Because compact stellar-mass objects, regardless of what they are composed of (we know they can't be baryonic because of constraints from primordial nucleosynthesis), make a definite prediction. They will cause microlensing of QSOs with a clear observational signature. There are a lot of observations of QSO variability, and microlensing theory is well understood, and the predictions do not correspond to the observations. End of story. That (some) QSO variability is due to microlensing and that this could be a sign of dark matter was a good theory in that it made testable predictions. But if those predictions were falsified, i.e. ruled out by observations, then the theory needs to go. The steady-state theory was in this sense a good theory. It was ruled out. Fred Hoyle, Geoff Burbidge and others tried to save it with ever more epicycles. Other people, such as Philip Morrison, moved on. |
#7
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'Dragons' of the Gamma-Ray Sky
In article , "David Staup"
writes: "Kent Paul Dolan" wrote in message ... Robert L. Oldershaw wrote: So why do so many astrophysicists assume the dark matter is composed of WIMPs, or even more exotic particles, while very few astrophysicists entertain the possibility that the observed stellar- mass ultracompacts might be the proverbial tip of the dark matter iceberg? Which part of Phillip's "ruled out by evidence" do you have trouble understanding? He's told you that at least twice. You keep trying to sneak your "dark stars as the dark matter" in one way or another, but the evidence has already eliminated them. can you provide links to this evidence? Back in 1996, the jury was still out (even then, Oldershaw was getting plenty of responses to his ideas): http://groups.google.de/group/sci.as...0a0b24fbc36b55 More evidence was in by the end of 2006, and your idea was looking worse: http://groups.google.de/group/sci.as...51f8625c33577f Just a couple of months ago, the nail in the coffin with a link to a paper which appeared in A&A: http://groups.google.de/group/sci.as...d81f9277023f52 I haven't seen you react to this paper at all. To my knowledge, no-one has published a paper demonstrating it is wrong, whereas many papers were published demonstrating why compact stellar-mass objects cannot be the lion's share of dark matter. Ignoring the evidence and touting the same hypothesis for decades despite the evidence is not good science. |
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