The Cosmic MeV Neutrino Background as a Laboratory for Black Hole Formation

Calculations of the cosmic rate of core collapses, and the associated neutrino flux, commonly assume that a fixed fraction of massive stars collapse to black holes. We argue that recent results suggest that this fraction instead increases with redshift. With relatively more stars vanishing as "unnovae" in the distant universe, the detectability of the cosmic MeV neutrino background is improved due to their hotter neutrino spectrum, and expectations for supernova surveys are reduced. We conclude that neutrino detectors, after the flux from normal SNe is isolated via either improved modeling or the next Galactic SN, can probe the conditions and history of black hole formation.Comment: 5 pages, 4 figures; Matches version published in Physics Letters

Intergenerational persistence of health: Do immigrants get healthier as they remain in the U.S. for more generations?

AbstractIt is well known that a substantial part of income and education is passed on from parents to children, generating substantial persistence in socioeconomic status across generations. In this paper, we examine whether another form of human capital, health, is also largely transmitted from generation to generation. Using data from the NLSY, we first present new evidence on intergenerational transmission of health outcomes in the U.S., including weight, height, the body mass index (BMI), asthma and depression for both natives and immigrants. We show that between 50% and 70% of the mothers’ health status persists in both native and immigrant children, and that, on average, immigrants experience higher persistence than natives in BMI. We also find that the longer immigrants remain in the U.S., the less intergenerational persistence there is and the more immigrants look like native children. Unfortunately, the more generations immigrant families remain in the U.S., the more children of immigrants resemble natives’ higher BMI

Pseudo-Familon Dark Matter

Motivated by a model of pseudo-Majoron dark matter, we show how the breaking of a global symmetry that acts nontrivially in lepton generation space can lead to a viable pseudo-familon dark matter candidate. Unlike the pseudo-Majoron, the pseudo-familon in our model decays primarily to charged leptons and can account for the excess observed in the cosmic ray electron and positron spectra.Comment: 12 pages LaTeX, 1 figur