tag:blogger.com,1999:blog-22973357.post8938567670196761696..comments2023-09-27T07:44:19.769-04:00Comments on Sabine Hossenfelder: Backreaction: News from AUGERSabine Hossenfelderhttp://www.blogger.com/profile/06151209308084588985noreply@blogger.comBlogger14125tag:blogger.com,1999:blog-22973357.post-27705253235133459282007-11-10T12:55:00.000-05:002007-11-10T12:55:00.000-05:00Hi Eric,Regarding statistics, I can really recomme...Hi Eric,<BR/><BR/>Regarding statistics, I can really recommend the talk by Aaron. He has very carefully explained the data analysis they have made. If I look at the image, it doesn't seem to convincing to me, but one gets easily fooled by points on maps. The chances that the observed UHECRs coincidentally fall into the regions around AGNs if they were isotropically distributed is extremely small.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-84717278871868264722007-11-09T19:10:00.000-05:002007-11-09T19:10:00.000-05:00The thing I missed earlier is that the AGN sources...The thing I missed earlier is that the AGN sources that they match up with the UHECRs are within 75 MPc, so that there is no GZK suppression. So, if the correlation holds up then this solves the mystery. However, I personally would like to see more statistics before I'm convinced that a correlation exists.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-73330337641846739582007-11-09T18:41:00.000-05:002007-11-09T18:41:00.000-05:00Thanks very much for the news. Great post, as alwa...Thanks very much for the news. Great post, as always!<BR/><BR/>Best,<BR/><BR/>SiddharthAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-46078703013163809082007-11-09T15:10:00.000-05:002007-11-09T15:10:00.000-05:00UHECRs being protons eliminates one of the better ...UHECRs being protons eliminates one of the better standard physics explanations for the unusual paths seen in nuclear emulsions taken up in baloons.<BR/><BR/>Probably the best paper for a review of weird stuff in cosmic ray emulsion film is <A HREF="http://arxiv.org/abs/hep-ph/0111163" REL="nofollow">this one</A> which postulated that they might be signs of the quark gluon plasma, but CarlBrannenhttps://www.blogger.com/profile/17180079098492232258noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-73502384328033203352007-11-09T09:06:00.000-05:002007-11-09T09:06:00.000-05:00If the sources of the UHECRs are AGN, then there m...If the sources of the UHECRs are AGN, then there must be something happening that we don't understand. I don't see how they they wouldn't interact with the CMB to fall below the GZK limit or why they wouldn't be deflected by the galactic magnetic field if cosmic ray primary is charged. The primary would have to be either neutral or very heavy. <BR/><BR/>EricAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-28585133195691303012007-11-08T20:23:00.000-05:002007-11-08T20:23:00.000-05:00Cosmic rays are caused by protons from outer space...<A HREF="http://bp0.blogger.com/_cldxKGOzgeM/RbBTZya_AiI/AAAAAAAAABg/2oqAg6_U7N0/s1600-h/cosmic+ray.gif" REL="nofollow">Cosmic rays are caused by protons from outer space. When a proton (shown in yellow) hits the air in the earth's upper atmosphere it produces many particles. Most of these decay or are absorbed in the atmosphere. One type of particle, called muons (shown in red), lives long PlatoHagelhttps://www.blogger.com/profile/00849253658526056393noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-41548976575447696722007-11-08T18:30:00.000-05:002007-11-08T18:30:00.000-05:00Hi Kris,I think their present statistic is too low...Hi Kris,<BR/><BR/>I think their present statistic is too low to say anything about the type of AGN. <BR/><BR/>Best,<BR/><BR/>B.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-72509974529483880032007-11-08T18:28:00.000-05:002007-11-08T18:28:00.000-05:00Hi Bee,You're right to leave open the possibility ...Hi Bee,<BR/><BR/>You're right to leave open the possibility that the UHECR are not coming from jets. Is there observational evidence of UHECR from AGN where jets are absent?<BR/><BR/>Briefly, in an environment with excess negative charge, accretion to an AGN could lead to charge concentration there. As described in the <A HREF="http://www.arxiv.org/abs/astro-ph/0606489" REL="nofollow">paper</A>Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-80233719945936383222007-11-08T18:09:00.000-05:002007-11-08T18:09:00.000-05:00I've just seen, there is an "Authors' Summary: Cor...I've just seen, there is an "<A HREF="http://www.sciencemag.org/cgi/content/full/318/5852/938/DC1" REL="nofollow"><I>Authors' Summary:</I> Correlation of the Highest-Energy Cosmic Rays with Nearby Extragalactic Objects</A>" to the Science paper, which is available without subscription. It has also a <A HREF="http://www.sciencemag.org/content/vol318/issue5852/images/data/938/DC1/318_938_Fa.jpg" stefanhttps://www.blogger.com/profile/09495628046446378453noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-19993202715594775092007-11-08T17:13:00.000-05:002007-11-08T17:13:00.000-05:00So is it safe to say the OhmyGod particles can be ...So is it safe to say the OhmyGod particles can be chalked up to experimental error?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-5956098130274646232007-11-08T16:59:00.000-05:002007-11-08T16:59:00.000-05:00KEWLActive galactic nuclei continue to be interest...KEWL<BR/><BR/>Active galactic nuclei continue to be interesting.eric gissehttps://www.blogger.com/profile/10598878490537720448noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-14547390737914011262007-11-08T16:54:00.000-05:002007-11-08T16:54:00.000-05:00Hi Kris,There's a difference between 'are of cours...Hi Kris,<BR/><BR/>There's a difference between 'are of course thought to be' and experimental confirmation. This difference is the reason why it's called science.<BR/><BR/>Sure if the source is neutral and emits positive charges only, there should be negative charge left behind. Just why would that be a significant effect? Best,<BR/><BR/>B.Sabine Hossenfelderhttps://www.blogger.com/profile/06151209308084588985noreply@blogger.comtag:blogger.com,1999:blog-22973357.post-85682351562407741232007-11-08T16:47:00.000-05:002007-11-08T16:47:00.000-05:00Hi Bee,Thanks for the update!Of course the UHECR a...Hi Bee,<BR/><BR/>Thanks for the update!<BR/><BR/>Of course the UHECR are thought to be produced by plasma jets from the AGN. Some jets are huge, radiating orders of magnitude more energy than the AGN host galaxy. It's also clear they have huge magnetic fields.<BR/><BR/>If protons or heavier nuclei are leaving the AGN region as UHECR, wouldn't that leave behind a surplus negative charge? As Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-22973357.post-36020332303705476082007-11-08T14:30:00.000-05:002007-11-08T14:30:00.000-05:00Dear Bee,ah, that's very interesting news! And tha...Dear Bee,<BR/><BR/><BR/>ah, that's very interesting news! And thanks for the pointer to the talk - I will have a look as soon as it will appear online there! <BR/><BR/>BTW, did they say anything about magnetic fields? I mean, cosmic rays with "lower" energies would be deflected more than higher-energetic rays by the intergalactic magnetic fields, which may destroy correlations for these stefanhttps://www.blogger.com/profile/09495628046446378453noreply@blogger.com