[{"id":291,"title":"Pre-registration of a test for statistical significance of a GALFA-HI -- WMAP ILC correlation ","sha":"464af33898155d92f8c2857e13e9512e","user_id":null,"state":"published","body":"In 2007 Gerrit Verschuur [proposed](http://dx.doi.org/10.1086/522685) that HI structures as seen in the Leiden-Argentina-Bonn 36' HI survey of the sky are correlated with structures in the WMAP sky, which are typically ascribed to the CMB. \r\n\r\nHe has recently proposed to see WMAP correlations in the higher-resolution GALFA-HI DR1 data. As the referee of this manuscript, I,([Joshua Peek](/users/5b0d532a4c510f697a292dec92d6c683)) required a test of statistical significance to publish.\r\n\r\nI proposed a test: I have fully reduced, but publicly unreleased GALFA-HI data that Verschuur has no access to. In the test, I select 34 WMAP peaks, to have [WMAP 7 year ILC brightness](http://lambda.gsfc.nasa.gov/product/map/dr4/ilc_map_get.cfm) greater than 0.1 mK, Galactic latitude \u003e 20 degrees, and extract ~2x2 degree regions in the unreleased area. I extract the same regions from GALFA-HI, and give both to Dr. Verschuur, without coordinates. If he can match many of these pairs, one can easily calculate the p-value -- 6 matches would be convincing. While it might be possible to leverage the dust-gas correlation using the Planck 353 maps to 'cheat', I believe this would be very difficult. \r\n\r\nDr. Verschuur, the editor, Dieter Hartmann, and I have agreed to this test. The test expires in Jan 1 2017, or when GALFA-HI DR2 become public, whichever comes first.","created_at":"2016-03-16T14:34:52.853Z","updated_at":"2016-04-14T20:42:29.676Z","zenodo_id":102226,"doi":"http://dx.doi.org/10.5281/zenodo.47726","subject":null,"tags":["pre-registration","test","interstellar medium"],"vote_count":1,"view_count":1,"score":1.1,"deleted":false,"muted":false,"tweeted":true,"attachment_file_name":null,"attachment_content_type":null,"attachment_file_size":null,"attachment_updated_at":null},{"id":385,"title":"On the Impossibility of Aggregating Individual Cloud Accretion Rates","sha":"83dcae03f859ebcb8e2e710af0ad1b47","user_id":null,"state":"published","body":"The rate of accretion onto the Milky Way (MW) by an individual cloud (or satellite) can be written as dM/dt = M v / R, where M is the cloud mass, v the cloud velocity toward the MW, and R is the distance from the cloud to the MW. Over the time t = R / v a mass M will accrete. This rate can be evaluated for many accreting objects; in the MW about a dozen high-velocity clouds (HVCs) are currently accreting onto the Galactic disk. This said, one cannot sum these accretion rates to determine the MW total rate of growth. For instance, in a scenario with all clouds having mass M, fixed accretion velocity v, and linearly increasing distances R, 2R, 3R, 4R... we would expect a mass M to accrete every R / v, providing a fixed accretion rate of M v / R. Yet by summing the accretion rates of each cloud we find M v / R times the harmonic series 1 + 1/2 + 1/3 + 1/4... This results in an infinite accretion rate. In practice, for currently known HVC distances, the summed accretion rate overestimates by 50% to 100%. ","created_at":"2017-05-24T01:40:31.529Z","updated_at":"2017-06-04T16:21:08.958Z","zenodo_id":582696,"doi":"https://doi.org/10.5281/zenodo.582696","subject":null,"tags":["astronomy","mathematics"],"vote_count":1,"view_count":1,"score":1.1,"deleted":false,"muted":false,"tweeted":true,"attachment_file_name":null,"attachment_content_type":null,"attachment_file_size":null,"attachment_updated_at":null}]