Day 1460

Monday.


1808.10460
What fraction of the density fluctuations in the Perseus cluster core is due to gas sloshing rather than AGN feedback?
Walker, Sanders, Fabian

Deep Chandra observations of the core of the Perseus cluster show a plethora of complex structure.  It has been found that when the observed density fluctuations in the intracluster medium are converted into constraints on AGN induced turbulence, the resulting turbulent heating rates are sufficient to balance cooling locally throughout the central 220 kpc.  However while the signatures of AGN feedback (inflated bubbles) dominate the central 60 kpc in X-ray images, beyond this radius the intracluster medium is increasingly shaped by the effects of gas sloshing, which can also produce subtle variations in X-ray surface brightness.  Use mock Chandra observations of gas sloshing simulations to investigate what fraction of the observed density fluctuations in the core of the Perseus galaxy cluster may originate from sloshing rather than AGN included feedback.  Outside 60 kpc, find that the observed level of the density fluctuations is broadly consistent with being produced by sloshing alone.  If this is the case, AGN-generated turbulence is likely to be insufficient in combating cooling outside 60 kpc.


1808.10493
No guaranteed neutrino astronomy without (enough) taus
Fargion, et al

Since 2013, the highest energy IceCube cascade showers overcame the common muon neutrino trans.  This fast flavor changes, above few tens TeV, has been indebt to the injection of the long searched astrophysical neutrino.  However for what concern the recent published ICECUBE 54 neutrino, high energy staring events (HESE) in 2016, as well as the most recent ones of 82 and 103 IceCube events (2017-2018) and the several dozens of thorough-going muon tracks formed around the IceCube, none of them are pointing or clustering toward any expected x, gamma or radio sources: no one in connection to GRB, no toward active BL Lac, neither to AGN source in Fermi catalog.  No clear correlation with nearby mass distribution (Local Group), nor with galactic plane.  Withal, there have not been any record of the expected double bang due to the tau neutrino birth and decay among several events above 200 TeV energy (disregard for a moment the most celebrated recent first correlated, but unique, muon track and the recent two tau possible identification); no any self-clustering events at tens TeV energy raised in most recent searches.  Furthermore, there is a tension between the internal HESE event spectra power index and the external thorough-going muon tracks one. As shown in the conclusions a more mundane (but a bit more abundant) prompt charmed atmospheric neutrino component may pollute and rule the data, explaining most of the present enlisted IceCube puzzles.  Review the last HESE event data shown in early and in most recent papers (and talks in Neutrino 2018) making the case for the simplest conclusions.  believe that most astrophysical neutrino signals are still hidden below the ashes of these new, anyway discovered, prompt atmospheric noise.