1905.03790
Dark matter signatures of supermassive black hole binaries
Naoz, Silk
A natural consequence of the galaxy formation paradigm is the existence of supermassive black hole (SMBH) binaries. Gravitational perturbations from a massive far away SMBH can induce high orbital eccentricities on dark matter particles orbiting the primary SMBH, via the eccentric Kozai-Lidov mechanism. This process yields an influx of dark matter particles into the primary SMBH ergosphere, where test particles linger for long timescales. This influx results in high self-gravitating densities, forming a dark matter clump extremely close to the SMBH. In such a situation, the gravitational wave emission between the dark matter clump and the SMBH is potentially detectable by LISA. If dark matter self-annihilates, the high densities of the clump will result in a unique co-detection of gravitational wave emission and high energy electromagnetic signatures.
Dark matter signatures of supermassive black hole binaries
Naoz, Silk
A natural consequence of the galaxy formation paradigm is the existence of supermassive black hole (SMBH) binaries. Gravitational perturbations from a massive far away SMBH can induce high orbital eccentricities on dark matter particles orbiting the primary SMBH, via the eccentric Kozai-Lidov mechanism. This process yields an influx of dark matter particles into the primary SMBH ergosphere, where test particles linger for long timescales. This influx results in high self-gravitating densities, forming a dark matter clump extremely close to the SMBH. In such a situation, the gravitational wave emission between the dark matter clump and the SMBH is potentially detectable by LISA. If dark matter self-annihilates, the high densities of the clump will result in a unique co-detection of gravitational wave emission and high energy electromagnetic signatures.
1905.03923
Distortions ind the surface of last scattering
Li, Dodelson, Hu
The surface of last scattering of the photons in the cosmic microwave background is not a spherical shell. Apart from its finite width, each photon experiences a different gravitational potential along its journey to us, leading to different travel times in different directions. Since all photons were released at the same cosmic time, the photons with longer travel times started farther away from us than those with shorter times. Thus, the surface of last scattering is corrugated, a deformed spherical shell. We present an estimator quadratic in the temperature and polarization fields that could provide a map of the time delays as a function of position on the sky. The signal to noise of this map could exceed unity for the dipole, thereby providing a rare insight into the universe on the largest observable scales.
1905.04229
Direct measurement of the cosmic-ray proton spectrum from 50 GeV to 10 TeV with the calorimetric electron telescope on the International Space Station
Adriani et al
In this paper, we present the analysis and results of a direct measurement of the cosmic-ray proton spectrum with the CALET instrument onboard the International Space Station, including the detailed assessment of systematic uncertainties. The observation period used in this analysis is from October 13, 2015 to August 31, 2018 (1054 days). We have achieved the very wide energy range necessary to carry out measurements of the spectrum from 50 GeV to 10 TeV covering, for the first time in space, with a single instrument the whole energy interval previously investigated in most cases in separate subranges by magnetic spectrometers (BESS-TeV, PAMELA, and AMS-02) and calorimetric instruments (ATIC, CREAM, and NUCLEON). The observed spectrum is consistent with AMS-02 but extends to nearly an order of magnitude higher energy, showing a very smooth transition of the power-law spectral index from -2.81 +- 0.03 (50--500 GeV) neglecting solar modulation effects (or -2.87 +- 0.06 including solar modulation effects in the lower energy region) to -2.56 +- 0.04 (1--10 TeV), thereby confirming the existence of spectral hardening and providing evidence of a deviation from a single power law by more than 3 sigma.
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