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CR dipole anisotropy
https://galprop.stanford.edu/forum/viewtopic.php?f=3&t=209
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Author:  mkruskal [ Tue Jun 02, 2015 9:54 am ]
Post subject:  CR dipole anisotropy

Hi,

I've come across a large number of papers that show plots of the "dipole anisotropy", delta, predicted by GALPROP and limits set from data. However, not a single one defines a formula for delta, and nowhere can I find a way to generate this myself from a GALPROP model. Admittedly, part of the problem is the number of places "anisotropic" appears in GALPROP documentation, making it very difficult to google. So can anyone tell me how to do this?

thanks,
Mike

Author:  strong [ Tue Jun 02, 2015 11:19 am ]
Post subject:  Re: CR dipole anisotropy

galprop does not explictly compute anisotropy, but it follows from the standard formula e.g. equation (1) in http://arxiv.org/abs/1505.02720
But that paper and others also demonstrates that this a far too simple approach, which requires more physics than is in galprop.

Author:  mkruskal [ Thu Jun 04, 2015 7:51 am ]
Post subject:  Re: CR dipole anisotropy

Thanks for the response, but that formula seems far too simple. I'm trying to estimate the CR anisotropy as a function of energy using the galprop output (e.g. figure 8 of http://arxiv.org/pdf/1108.1023.pdf). I've seen a bunch of plots that show the "galprop" prediction for anisotropy, but I haven't been able to find any detail on the calculation

Author:  strong [ Thu Jun 04, 2015 9:33 am ]
Post subject:  Re: CR dipole anisotropy

That is the standard formula following from the definition of diffusion. But certainly it is too simple, as many papers have pointed out. Probably however it was used in the paper you cite.

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