High-energy neutrinos from reverse shocks in choked and successful relativistic jets

Highly relativistic jets are a key element of current gamma-ray burst models, where the jet kinetic energy is converted to radiation energy at optically thin shocks. High-energy neutrinos are also expected, from interactions of protons accelerated in the same shocks. Here we revisit the early evolution of a relativistic jet, while the jet is still inside the star, and investigate its neutrino emission. In particular we study propagation of mildly relativistic and ultrarelativistic jets through a type Ib progenitor, and follow reverse shocks as the jets cross the star. We show that protons can be accelerated to 10^4-10^5 GeV at reverse shocks, and efficiently produce mesons. The mesons experience significant cooling, suppressing subsequent neutrino emission. We show, however, that the neutrino yield from the reverse shock is still reasonably large, especially for low-luminosity and long-duration jets, where meson cooling is less severe. We discuss implications of our results in the context of neutrinos from choked jets, which are completely shock heated and do not break out of the star. From a choked jet with isotropic equivalent energy of 10^{53} erg at 10 Mpc, we expect ~20 neutrino events at IceCube.Comment: 11 pages, 7 figures, 2 tables; accepted for publication in Physical Review

Probing dark gamma-ray bursts with neutrinos

Highly relativistic jets are a key element of current gamma‐ray burst (GRB) models, where the jet kinetic energy is converted to radiation energy at optically thin shocks. Mildly relativistic jets with smaller Lorentz factors are typically optically thick to gamma rays, and do not produce the spectacular GRB phenomenon. Jets which stall inside the progenitor similarly do not produce a GRB. However, various studies suggest that these jets are more common than GRB‐producing jets. Here we report on our study of high‐energy neutrino emission from these hidden jets. We describe the detection prospects with near‐future neutrino detectors, and discuss how the presence of jets can be studied with neutrinos. The neutrino horizon for hidden jets is of order 10 Mpc, a volume which contains at least a few supernova per year

Dark matter annihilation from intermediate-mass black holes: Contribution to the extragalactic gamma-ray background

We investigate contributions to the extragalactic gamma-ray background (EGB) due to neutralino dark matter (DM) pair-annihilation into photons, from DM density enhancements (minispikes) surrounding intermediate-mass black holes (IMBHs). We focus on two IMBH formation scenarios; our conservative scenario where IMBHs are remnants of Population-III stars, and our optimistic scenario here IMBHs are formed in protogalactic disks. In both scenarios, their formation in pregalactic halos at high redshift lead to the formation of minispikes that are bright sources of gamma-ray photons. Taking into account minispike depletion processes, we only sum contributions from a cosmological distribution of IMBHs with maintained minispikes. Our conservative scenario (BH mass 10^2 M_sun with a r^{-3/2} minispike) predicts gamma-ray fluxes that are an order larger than the equivalent flux, using the same DM parameters (mass 100 GeV and annihilation cross-section 3 \times 10^{-26} cm^3 s^{-1}, from the host halo without IMBH minispikes. Our optimistic scenario (BH mass 10^5 M_sun with a r^{-7/3} minispike) predicts fluxes that are three orders larger, that can reach current EGB observations taken by EGRET (DM parameters as above). This fact may serve interesting consequences for constraining DM parameters and elucidating the true nature of IMBHs. Additionally, we determine the spectra of DM annihilation into monochromatic gamma-rays, and show that its flux can be within observational range of GLAST, providing a potential `smoking-gun' signature of DM.Comment: 11 pages, 6 figures, 2 tables, accepted for publication in Phys.Rev.

Probing dark gamma-ray bursts with neutrinos

Highly relativistic jets are a key element of current gamma‐ray burst (GRB) models, where the jet kinetic energy is converted to radiation energy at optically thin shocks. Mildly relativistic jets with smaller Lorentz factors are typically optically thick to gamma rays, and do not produce the spectacular GRB phenomenon. Jets which stall inside the progenitor similarly do not produce a GRB. However, various studies suggest that these jets are more common than GRB‐producing jets. Here we report on our study of high‐energy neutrino emission from these hidden jets. We describe the detection prospects with near‐future neutrino detectors, and discuss how the presence of jets can be studied with neutrinos. The neutrino horizon for hidden jets is of order 10 Mpc, a volume which contains at least a few supernova per year

Neutrino Constraints on the Dark Matter Total Annihilation Cross Section

In the indirect detection of dark matter through its annihilation products, the signals depend on the square of the dark matter density, making precise knowledge of the distribution of dark matter in the Universe critical for robust predictions. Many studies have focused on regions where the dark matter density is greatest, e.g., the Galactic Center, as well as on the cosmic signal arising from all halos in the Universe. We focus on the signal arising from the whole Milky Way halo; this is less sensitive to uncertainties in the dark matter distribution, and especially for flatter profiles, this halo signal is larger than the cosmic signal. We illustrate this by considering a dark matter model in which the principal annihilation products are neutrinos. Since neutrinos are the least detectable Standard Model particles, a limit on their flux conservatively bounds the dark matter total self-annihilation cross section from above. By using the Milky Way halo signal, we show that previous constraints using the cosmic signal can be improved on by 1-2 orders of magnitude; dedicated experimental analyses should be able to improve both by an additional 1-2 orders of magnitude.Comment: 8 pages, 4 figures; Matches version published in Phys. Rev.

Diffuse neutrino background from past core-collapse supernovae

Core-collapse supernovae are among the most powerful explosions in the universe, emitting thermal neutrinos that carry away the majority of the gravitational binding energy released. These neutrinos create a diffuse supernova neutrino background (DSNB), one of the largest energy budgets among all radiation backgrounds. Detecting the DSNB is a crucial goal of modern high-energy astrophysics and particle physics, providing valuable insights in both core-collapse modeling, neutrino physics, and cosmic supernova rate history. In this review, we discuss the key ingredients of DSNB calculation and what we can learn from future detections, including black-hole formation and non-standard neutrino interactions. Additionally, we provide an overview of the latest updates in neutrino experiments, which could lead to the detection of the DSNB in the next decade. With the promise of this breakthrough discovery on the horizon, the study of DSNB holds enormous potential for advancing our understanding of the Universe.Comment: 21 pages, 8 figures. Invited review article submitted to Proceedings of the Japan Academy, Series B. Figures are made using the numerical codes that accompany this paper; see https://github.com/shinichiroando/PyDSNB/tree/mai

Non-thermal neutrinos from supernovae leaving a magnetar

Under the fossil field hypothesis of the origin of magnetar magnetic fields, the magnetar inherits its magnetic field from its progenitor. We show that during the supernova of such a progenitor, protons may be accelerated to ∼10^4 GeV as the supernova shock propagates in the stellar envelope. Inelastic nuclear collisions of these protons produce a flash of high-energy neutrinos arriving a few hours after thermal (10 MeV) neutrinos. The neutrino flash is characterized by energies up to O(100) GeV and durations seconds to hours, depending on the progenitor: those from smaller Type Ibc progenitors are typically shorter in duration and reach higher energies compared to those from larger Type II progenitors. A Galactic Type Ib supernova leaving behind a magnetar remnant will yield up to ∼160 neutrino-induced muon events in Super-Kamiokande, and up to ∼7000 in a km^3 class detector such as IceCube, providing a means of probing supernova models and the presence of strong magnetic fields in the stellar envelope

Cross Correlation of the Extragalactic Gamma-ray Background with Thermal Sunyaev-Zel'dovich Effect in the Cosmic Microwave Background

Cosmic rays in galaxy clusters are unique probes of energetic processes operating with large-scale structures in the Universe. Precise measurements of cosmic rays in galaxy clusters are essential for improving our understanding of non-thermal components in the intracluster-medium (ICM) as well as the accuracy of cluster mass estimates in cosmological analyses. In this paper, we perform a cross-correlation analysis with the extragalactic gamma-ray background and the thermal Sunyaev-Zel'dovich (tSZ) effect in the cosmic microwave background. The expected cross-correlation signal would contain rich information about the cosmic-ray-induced gamma-ray emission in the most massive galaxy clusters at $z\sim0.1-0.2$. We analyze the gamma-ray background map with 8 years of data taken by the Large Area Telescope onboard Fermi satellite and the publicly available tSZ map by Planck. We confirm that the measured cross-correlation is consistent with a null detection, and thus it enables us to put the tightest constraint on the acceleration efficiency of cosmic ray protons at shocks in and around galaxy clusters. We find the acceleration efficiency must be below 5\% with a $2\sigma$ confidence level when the hydrostatic mass bias of clusters is assumed to be 30\%, and our result is not significantly affected by the assumed value of the hydrostatic mass bias. Our constraint implies that the non-thermal cosmic-ray pressure in the ICM can introduce only a $\le 3\%$ level of the hydrostatic mass bias, highlighting that cosmic rays alone do not account for the mass bias inferred by the Planck analyses. Finally, we discuss future detectability prospects of cosmic-ray-induced gamma rays from the Perseus cluster for the Cherenkov Telescope Array.Comment: 19 pages, 15 figures, 1 table. Accepted for publication in Phys. Rev.

Synergism between human tumor necrosis factor and human interferon-alpha: effects on cells in culture.

The cytostatic and cytotoxic effects of highly purified natural human tumor necrosis factor (HuTNF-alpha) and natural human interferon-alpha (HuIFN-alpha) on 23 cell lines were studied in vitro. Natural HuTNF-alpha showed cytostatic and cytotoxic effects on PC-9, KHG-2, HT-1197, KG-1 and L-929 cells, and HuIFN-alpha showed both effects on KHG-2 and Daudi cells. A mixture of HuTNF-alpha and HuIFN-alpha (1:1, by unit) showed cytostatic and cytotoxic effects on HuTNF-alpha- or HuIFN-alpha-resistant cell lines such as KB, KATO-III, HEp-2, P-4788, as well as on HuTNF-alpha- or HuIFN-alpha-susceptible cells. Thus, the combined preparation of HuTNF-alpha and HuIFN-alpha expanded the spectrum of sensitive cells. The dosage of the mixed preparation required to produce 50% inhibition of cell growth was less than 20% of that of HuTNF-alpha or HuIFN-alpha alone. These results indicate that the cytostatic and cytotoxic effects of HuTNF-alpha and HuIFN-alpha are synergistically enhanced when they are administered together.</p

The Andromeda Gamma-Ray Excess: Background Systematics of the Millisecond Pulsars and Dark Matter Interpretations

Since the discovery of an excess in gamma rays in the direction of M31, its cause has been unclear. Published interpretations focus on a dark matter or stellar related origin. Studies of a similar excess in the Milky Way center motivate a correlation of the spatial morphology of the signal with the distribution of stellar mass in M31. However, a robust determination of the best theory for the observed excess emission is very challenging due to large uncertainties in the astrophysical gamma-ray foreground model. Here we perform a spectro-morphological analysis of the M31 gamma-ray excess using state-of-the-art templates for the distribution of stellar mass in M31 and novel astrophysical foreground models for its sky region. We construct maps for the old stellar populations of M31 based on observational data from the PAndAS survey and carefully remove the foreground stars. We also produce improved astrophysical foreground models by using novel image inpainting techniques based on machine learning methods. We find that our stellar maps, taken as a proxy for the location of a putative population of millisecond pulsars in the bulge of M31, reach a statistical significance of $5.4\sigma$, making them as strongly favoured as the simple phenomenological models usually considered in the literature, e.g., a disk-like template with uniform brightness. Our detection of the stellar templates is robust to generous variations of the astrophysical foreground model. Once the stellar templates are included in the astrophysical model, we show that the dark matter annihilation interpretation of the signal is unwarranted. Using the results of a binary population synthesis model we demonstrate that a population of about one million unresolved MSPs could naturally explain the observed gamma-ray luminosity per stellar mass, energy spectrum, and stellar bulge-to-disk flux ratio.Comment: 15 pages, 11 figures, comments are welcom