Neutrinos traveling over cosmic distances are ideal probes of new physics. We leverage on the approaching detection of the diffuse supernova neutrino background (DSNB) to explore whether, if the DSNB showed departures from theoretical predictions, we could attribute such modifications to new physics unequivocally. In order to do so, we focus on visible neutrino decay. Many of the signatures from neutrino decay are degenerate with astrophysical unknowns entering the DSNB modeling. Next generation neutrino observatories, such as Hyper-Kamiokande, JUNO, as well as DUNE, will set stringent limits on a neutrino lifetime over mass ratio $τ/m \sim 10^{9}$-$10^{10}$ s eV$^{-1}$ at $90\%$ C.L., if astrophysical uncertainties and detector backgrounds were to be fully under control. However, if the lightest neutrino is almost massless and the neutrino mass ordering is normal, constraining visible decay will not be realistically possible in the coming few decades. We also assess the challenges of distinguishing among different new physics scenarios (such as visible decay, invisible decay, and quasi-Dirac neutrinos), all leading up to similar signatures in the DSNB. This work shows that the DSNB potential for probing new physics strongly depends on an improved understanding of the experimental backgrounds at next generation neutrino observatories as well as progress in the DSNB modeling.
We propose a new method to search for axion-like particles (ALPs) based on the gamma-rays produced concomitant with high-energy astrophysical neutrinos. The existence of high-energy neutrinos implies production of gamma-rays in the same sources. Photons can convert into ALPs in the sources' magnetic fields, and will travel as ALPs through extragalactic space. Back-conversion in the Milky Way's magnetic field leads to a diffuse anisotropic high-energy photon flux that existing and upcoming gamma-ray detectors, like HAWC, CTA, and LHAASO can detect. This method probes unexplored ALP parameter sp…
The signatures for the existence of dark matter are revealed only through its gravitational interaction. Theoretical arguments support that the Weakly Interacting Massive Particle (WIMP) can be a class of dark matter and it can annihilate and/or decay to Standard Model particles, among which neutrino is a favorable candidate. We show that the proposed 50 kt Magnetized Iron CALorimeter (MagICAL) detector under the India-based Neutrino Observatory (INO) project can play an important role in the indirect searches of Galactic diffuse dark matter in the neutrino and antineutrino mode separately. We…
The Pierre Auger Observatory is the largest astroparticle experiment in operation. Complementary to the measurements of the charged ultra-high energy (UHE) cosmic rays, it provides a very good sensitivity to the detection of UHE photons and neutrinos. Since the photon and neutrino fluxes are correlated to the acceleration mechanisms of charged particles, searches for these neutral particles enhance the multi-messenger understanding of UHE cosmic-ray sources and of transient astrophysical phenomena. In addition, searches for diffuse fluxes may bring information about exotic scenarios such as th…
At the beginning of 2016, LIGO reported the first-ever direct detection of gravitational waves. The measured signal was compatible with the merger of two black holes of about 30 solar masses, releasing about 3 solar masses of energy in gravitational waves. We consider the possible neutrino emission from a binary black hole merger relative to the energy released in gravitational waves and investigate the constraints coming from the non-detection of counterpart neutrinos, focusing on IceCube and its energy range. The information from searches for counterpart neutrinos is combined with the diffus…
The IceCube Neutrino Observatory is a cubic kilometer-sized detector designed to detect neutrinos of astrophysical origin. However, muons created by cosmic rays interacting in the atmosphere pose a significant background for these astrophysical neutrinos particularly in the southern equatorial sky. Identifying neutrino events that start in the detector allows us to reduce the atmospheric muon component while retaining a high rate of starting neutrino events. The method presented today also rejects atmospheric neutrinos if they are accompanied by muons from the same cosmic ray shower, lowering …
The IceCube Neutrino Observatory has discovered a diffuse all-flavor flux of high-energy astrophysical neutrinos. However, the corresponding astrophysical sources have not yet been identified. Neither significant point sources nor significant angular correlations of event directions have been observed by IceCube or other instruments to date. We present a new method to interpret the non-observation of angular correlations in terms of exclusions on the strength and number of point-like sources in generic astrophysical scenarios. Additionally, we constrain the presence of these sources taking int…
Although IceCube has discovered a diffuse astrophysical neutrino flux, the underlying sources of these neutrinos remain unknown. Transient astrophysical objects, such as fast radio bursts (FRBs), could explain a large percentage of the measured flux. We present the analysis techniques of IceCube searches for MeV to TeV neutrinos from FRBs. As no significant correlation between IceCube neutrinos and FRBs has been found, we present the first limit on MeV neutrino emission from FRBs and the most constraining limits for neutrinos with GeV to TeV energies. We also describe the prospects for future …
The advent of gadolinium-loaded Super-Kamiokande (SK-Gd) and of the soon-to-start JUNO liquid scintillator detector marks a substantial improvement in the global sensitivity for the Diffuse Supernova Neutrino Background (DSNB). The present article reviews the detector properties most relevant for the DSNB searches in both experiments and estimates the expected signal and background levels. Based on these inputs, we evaluate the sensitivity of both experiments individually and combined. Using a simplified statistical approach, we find that both SK-Gd and JUNO have the potential to reach $>$3$σ$…
The potential of diffuse Galactic Ridge neutrino measurements to constrain dark matter
Instituto de Fisica Teorica UAM-CSIC, Universidad Autonoma de Madrid（马德里自治大学理论物理研究所）；Departamento de Fisica Teorica, M-15, Universidad Autonoma de Madrid（马德里自治大学理论物理系）；Department of Information Technology, Escuela Politécnica Superior, Universidad San Pablo-CEU（圣巴勃罗ceu大学高等理工学院信息技术系）
A Search for a keV Signature of Radiatively Decaying Dark Matter with Suzaku XIS Observations of the X-ray Diffuse Background
我们用朱雀XIS对来自非重子暗物质的0.5至7 keV之间的X射线发射线进行了最深的搜索。选择与银河系有关的暗物质作为目标，以获得最佳的信噪比。我们从朱雀天文台的资料库中选取了187组以X射线散射背景为主的空白天空区域的数据。数据集是从2005年到2013年。仪器的响应是由蟹状星云的多个校准数据集调整的。我们还改进了减去仪器源谱线的技术。这些能谱可以用太阳系周围电荷交换产生的X射线辐射、银河系内部和周围的热等离子体以及河外点源的叠加来描述。搜索窄发射谱线的信号，并且考虑盲搜索方法（别处寻找效应）来评价检测的显著性。我们的研究结果显示，没有显着的检测到发射线功能的暗物质。3 $σ$的上限为1至7 keV之间的发射线强度的$\sim10^{-2}$光子cm $^{-2}$ s $^{-1}$ sr $^{-1}$，或$\sim 5\times10^{-4}$光子cm $^{-2}$ s $^{-1}$ sr $^{-1}$ per $M_\odot$ pc $^{-2}$，假设暗物质分布与银河系旋转曲线。作为暗物质候选者的无菌中微子的参数也受到限制。
The ANtarctic Impulsive Transient Antenna (ANITA) long-duration balloon experiment flies an interferometric radio array over Antarctica with a primary goal of detecting impulsive Askaryan radio emission from ultra-high-energy neutrinos interacting in the ice sheet. The third and fourth ANITA flights were completed in January 2015 and December 2016, respectively, obtaining the most stringent limits on the diffuse ultra-high-energy neutrino flux above 10$^{19.5}$ eV to date. We also discuss ongoing analyses and the proposed Payload for Ultrahigh Energy Observations (PUEO), the successor to the A…
The excess of neutrino candidate events detected by IceCube from the direction of TXS 0506+056 has generated a great deal of interest in blazars as sources of high-energy neutrinos. In this study, we analyze the publicly available portion of the IceCube dataset, performing searches for neutrino point sources in spatial coincidence with the blazars and other active galactic nuclei contained in the Fermi 3LAC and the Roma BZCAT catalogs, as well as in spatial and temporal coincidence with flaring sources identified in the Fermi Collaboration's All-Sky Variability Analysis (FAVA). We find no evid…
Gamma-ray bursts (GRBs) are among the most powerful events observed in our universe and have long been considered as possible sources of ultra-high-energy cosmic rays, which makes them promising neutrino source candidates. Previous IceCube searches for neutrino correlations with GRBs focused on the prompt (main emission) phase of the GRB and found no significant correlation between neutrino events and the observed GRBs. This motivates us to extend our search beyond the prompt phase. We perform analyses looking for evidence of neutrino emission up to 14 days before and after the prompt phase of…
In the absence of high-statistics supernova neutrino measurements, estimates of the diffuse supernova neutrino background (DSNB) hinge on the precision of simulations of core-collapse supernovae. Understanding the cooling phase of protoneutron star (PNS) evolution ($\gtrsim1\,{\rm s}$ after core bounce) is crucial, since approximately 50% of the energy liberated by neutrinos is emitted during the cooling phase. We model the cooling phase with a hybrid method by combining the neutrino emission predicted by 3D hydrodynamic simulations with several cooling-phase estimates, including a novel two-p…
The Diffuse Gamma-Ray Background (DGB) above 100 GeV at high-latitudes is expected to be produced by unresolved extragalactic objects such as active galactic nuclei, isotropic Galactic gamma-rays, and possible emission from dark matter annihilations or decays in the Galactic dark matter halo. The DGB has been observed up to nearly 1 TeV, but has yet to be detected at higher energies. Detections or stringent limits on the DGB above this energy would have strong multimessenger consequences, such as constraining the origin of astrophysical neutrinos observed in IceCube. The High Altitude Water Ch…
Future large liquid-scintillator (LS) detectors are competitive with and complementary to the water-Cherenkov detectors on the searches for diffuse supernova neutrino background and nucleon decay. In a companion paper, we have performed a systematic calculation of the neutral-current (NC) background induced by atmospheric neutrino interactions on $^{12}{\rm C}$ nuclei in LS detectors, which are expected to be crucially important for the experimental searches for the diffuse supernova neutrino background and nucleon decay. In this paper, we perform a systematic study on the measurement of the N…
Search for Point-Like Sources of Ultra-High Energy Neutrinos at the Pierre Auger Observatory and Improved Limit on the Diffuse Flux of Tau Neutrinos
皮埃尔·俄歇天文台的表面探测器阵列可以探测到能量在10^17 eV到10^20 eV之间的中微子，这些中微子来自于+55度以南和-65度以北的天空中的点状源。人们已经对大气中各种中微子相互作用（下行中微子）和地壳中τ中微子相互作用产生的τ轻子衰变（掠地中微子）产生的高度倾斜的大范围空气簇射进行了研究。截至2010年5月31日，在数据中没有发现候选中微子。这相当于全表面探测器阵列在掠地通道中的等效曝光时间约为3.5年，在下行通道中的等效曝光时间约为2年。导出了τ中微子扩散通量的一个改进的上限。从点源的中微子通量的上限已被推导出作为源decompensate的函数。假设来自点状源的中微子通量k_PS E ^-2为微分，则90% C. L。通过对掠地中微子和下行中微子的研究，在很宽的磁偏角范围内分别得到了k_PS的上限值约为5 x 10 ^-7和2.5 x 10 ^-6 GeV cm ^-2 s ^-1。
The surface detector array (SD) of the Pierre Auger Observatory is sensitive to neutrinos at energies in the 100 PeV to 100 EeV range. This sensitivity, together with its large acceptance, makes it a complementary detector to other neutrino telescopes, which have their peak sensitivities at lower energies. The neutrino-induced air showers that the SD of the Pierre Auger Observatory is sensitive to can be divided into those induced by interactions of neutrinos of any flavor deep in the atmosphere, and those induced by charged-current interactions of tau neutrinos in the Earth's crust. Both of t…
The ANtarctic Impulsive Transient Antenna (ANITA) long-duration balloon payload searches for Askaryan radio emission from ultra-high-energy ($>10^{18}$ eV) neutrinos interacting in Antarctic ice. ANITA is also sensitive to geomagnetic radio emission from extensive air showers (EAS). This talk summarizes recently released results from the third flight of ANITA, which flew during the 2014-2015 Austral summer. The most sensitive search from ANITA-III identified one neutrino candidate with an a priori background estimate of 0.7$^{+0.5}_{-0.3}$. When combined with previous flights, ANITA sets the b…
The ANTARES deep sea neutrino telescope has been taking data continuously since its completion in 2008. With its excellent view of the Galactic plane and good angular resolution the telescope can constrain the origin of the diffuse astrophysical neutrino flux reported by IceCube. Assuming various spectral indices for the energy spectrum of neutrino emitters, the Southern sky and in particular central regions of our Galaxy have been studied searching for point-like objects, for extended regions of emission, and for signal from transient objects selected through multi-messenger observations. For…
Located at the South Pole, the IceCube Neutrino Observatory is the world largest neutrino telescope, instrumenting one cubic kilometre of Antarctic ice at a depth between 1450m to 2450m. In 2013 IceCube reported the first observations of a diffuse astrophysical high-energy neutrino flux. Although the IceCube Collaboration has identified more than 100 high-energy neutrino events, the origin of this neutrino flux is still not known. Blazars, a subclass of Active Galactic Nuclei and one of the most powerful classes of objects in the Universe, have long been considered promising sources of high en…
Identification of ultra-high-energy neutrinos in vertical air showers with surface detectors
Instituto Galego de Física de Altas Enerxías (IGFAE), Universidade de Santiago de Compostela（加利西亚高能物理研究所，圣地亚哥-德孔波斯特拉大学）；Departamento de Física, Instituto Superior Técnico (IST), Universidade de Lisboa（里斯本大学高等理工学院物理系）；Laboratório de Instrumentação e Física Experimental de Partículas (LIP)（粒子物理与实验仪器实验室）
