Abstracts of Interest
Selected by:
Imogen
Abstract: 2307.09170
Full Text: [ PostScript, PDF]
Full Text: [ PostScript, PDF]
Title:Hunting for bumps in the diffuse high-energy neutrino flux
Download PDFAbstract: The origin of the TeV--PeV astrophysical neutrinos seen by the IceCube telescope is unknown. If they are made in proton-photon interactions in astrophysical sources, their spectrum may show bump-like features. We search for such features in the 7.5-years High-Energy Starting Events (HESE), and forecast the power of such searches using larger data samples expected from upcoming telescopes. Present-day data reveals no evidence of bump-like features, which allows us to constrain candidate populations of photohadronic neutrino sources. Near-future forecasts show promising potential for stringent constraints or decisive discovery of bump-like features. Our results provide new insight into the origins of high-energy astrophysical neutrinos, complementing those from point-source searches.
Abstract: 2307.08967
Full Text: [ PostScript, PDF]
Full Text: [ PostScript, PDF]
Title:New estimation of the nuclear de-excitation line emission from the supernova remnant Cassiopeia A
Download PDFAbstract: MeV nuclear de-excitation lines serve as a unique tool to study low-energy cosmic rays (CRs), containing both spectral and elemental information of the interacting material. In this paper, we estimated the possible nuclear de-excitation lines from the young supernova remnant Cassiopeia A. Given different CR spectral shapes and interacting materials, we found the predicted fluxes of strong narrow line emissions from the remnant are highly model-dependent, ranging from about $1\times10^{-10}\,{\rm \,cm^{-2}\,s^{-1}}$ to $1\times10^{-6}\, {\rm \,cm^{-2}\,s^{-1}}$ for the 4.44 MeV narrow line and from about $4\times10^{-11}\,{\rm \,cm^{-2}\,s^{-1}}$ to $2\times10^{-7}{\rm \,cm^{-2}\,s^{-1}}$ for the 6.13 MeV narrow line, respectively. Based on the new estimation, we also discussed the detection probability of these line emissions against the MeV diffuse Galactic background under different assumptions of instrument response functions.
Abstract: 2307.08820
Full Text: [ PostScript, PDF]
Full Text: [ PostScript, PDF]
Title:The Luminous, Hard State Can't Be MAD
Download PDFAbstract: We present a straightforward argument for why the luminous, hard state of black hole X-ray binaries (BHXRBs) cannot always be associated with a magnetically arrested accretion disc (MAD). It relies on three core premises: 1) that the type-C quasi-periodic oscillation (QPO) is best explained by Lense-Thirring (LT) precession of a tilted, inner, hot flow; 2) that observed optical and infrared (IR) QPOs with the same or lower frequency as the type-C QPO suggest the jet, too, must precess in these systems; and 3) that numerical simulations of MADs show that their strong magnetic fields promote alignment of the disc with the black hole and, thereby, suppress LT precession. If all three premises hold true, then, at least whenever the optical and IR QPOs are observed alongside the type-C QPO, these systems cannot be in the MAD state. Extending the argument further, if the type-C QPO is always associated with LT precession, then it would rule out MADs anytime this timing feature is seen, which covers nearly all BHXRBs when they are in the luminous, hard and hard-intermediate states.
Abstract: 2307.08744
Full Text: [ PostScript, PDF]
Full Text: [ PostScript, PDF]
Title:New constraints on the gamma-ray and high energy neutrino fluxes from the circumstellar interaction of SN 2023ixf
Download PDFAbstract: The recent supernova, SN 2023ixf, one of the closest observed type II SNe has revealed the presence of a dense circumstellar material (CSM). Interaction of the SN ejecta with this dense CSM may create high energy protons of PeV energies through shock acceleration. These accelerated protons then colliding with the CSM (inelastic $pp$ collision) can produce secondaries such as high energy gamma-rays and neutrinos. However, no gamma-rays and neutrinos have been detected by Fermi-LAT and IceCube from this event. Indeed, Fermi-LAT has placed an upper limits on the gamma-ray flux above $100$~MeV to be $2.6 \times 10^{-11}~\rm erg~cm^{-2}~s^{-1}$. On the other hand IceCube's upper limit on muon neutrino flux is $7.3\times 10^{-2} ~\rm GeV~cm^{-2}$. Using these experimental constraints and shock-CSM properties derived from observations, we obtain new upper limits on the gamma-ray ($10^{-11}~\rm erg~cm^{-2}~s^{-1}$) and neutrino ($10^{-3}~\rm GeV~cm^{-2}$) fluxes from SN 2023ixf produced via the $pp$ interaction channel. While we found the gamma-ray flux to be consistent with Fermi-LAT's upper limit, the neutrino flux is found to be about $2$ order smaller than the IceCube's upper limit. We further analyse detection prospects of such secondary signals from future SN 2023 like events with upcoming detectors, CTA and IceCube-Gen2 and found to have great discovery potential, if any event occurs within $7$ Mpc.
Abstract: 2307.08735
Full Text: [ PostScript, PDF]
Full Text: [ PostScript, PDF]
Title:Neutrino Signatures of One Hundred 2D Axisymmetric Core-Collapse Supernova Simulations
Download PDFAbstract: We present in this paper a public data release of an unprecedentedly-large set of core-collapse supernova (CCSN) neutrino emission models, comprising one hundred detailed 2D-axisymmetric radiation-hydrodynamic simulations evolved out to as late as ~5 seconds post-bounce and spanning a extensive range of massive-star progenitors. The motivation for this paper is to provide a physically and numerically uniform benchmark dataset to the broader neutrino detection community to help it characterize and optimize subsurface facilities for what is likely to be a once-in-a-lifetime galactic supernova burst event. With this release we hope to 1) help the international experiment and modeling communities more efficiently optimize the retrieval of physical information about the next galactic core-collapse supernova, 2) facilitate the better understanding of core-collapse theory and modeling among interested experimentalists, and 3) help further integrate the broader supernova neutrino community.
Abstract: 2307.08728
Full Text: [ PostScript, PDF]
Full Text: [ PostScript, PDF]
Title:Small-Scale Magnetic Fields are Critical to Shaping Solar Gamma-Ray Emission
Download PDFAbstract: The Sun is a bright gamma-ray source due to hadronic cosmic-ray interactions with solar gas. While it is known that incoming cosmic rays must generally first be reflected by solar magnetic fields to produce outgoing gamma rays, theoretical models have yet to reproduce the observed spectra. We introduce a simplified model of the solar magnetic fields that captures the main elements relevant to gamma-ray production. These are a flux tube, representing the network elements, and a flux sheet, representing the intergranule sheets. Both the tube and sheet have a horizontal size of order $100~{\rm km}$ and serve as sites where cosmic rays are reflected and gamma rays are produced. Despite having no tuning to match gamma-ray data, our model produces a gamma-ray spectrum that reasonably matches both the hard spectrum seen by Fermi-LAT data at $\text{1--200}~{\rm GeV}$ and the considerably softer spectrum seen by HAWC at near $10^3~{\rm GeV}$. We show that lower-energy ($\lesssim 10~{\rm GeV}$) gamma rays are primarily produced in the network elements and higher-energy ($\gtrsim {\rm few} \times 10~{\rm GeV}$) gamma rays in the intergranule sheets. Notably, the spectrum softening observed by HAWC results from the limited effectiveness of capturing and reflecting $\sim 10^4~{\rm GeV}$ cosmic rays by the finite-sized intergranule sheets. Our study is important for understanding cosmic-ray transport in the solar atmosphere and will lead to insights about small-scale magnetic fields in the quiet photosphere.
Abstract: 2307.09460
Full Text: [ PostScript, PDF]
Full Text: [ PostScript, PDF]
Title:Probing Light Dark Matter through Cosmic-Ray Cooling in Active Galactic Nuclei
Download PDFAbstract: Recent observations of high-energy neutrinos from active galactic nuclei (AGN), NGC 1068 and TXS 0506+056, suggest that cosmic rays (CRs) are accelerated in the vicinity of the central supermassive black hole and high-energy protons and electrons can cool efficiently via interactions with ambient photons and gas. The dark matter density may be significantly enhanced near the central black hole, and CRs could lose energies predominantly due to scatterings with the ambient dark matter particles. We propose CR cooling in AGN as a new probe of dark matter-proton and dark matter-electron scatterings. Under plausible astrophysical assumptions, our constraints on sub-GeV dark matter can be the strongest derived to date. Some of the parameter space favored by thermal light dark matter models might already be probed with current multimessenger observations of AGN.
Abstract: 2307.07576
Full Text: [ PostScript, PDF]
Full Text: [ PostScript, PDF]
Title:Search for Extended Sources of Neutrino Emission in the Galactic Plane with IceCube
Download PDFAbstract: The Galactic plane, harboring a diffuse neutrino flux, is a particularly interesting target to study potential cosmic-ray acceleration sites. Recent gamma-ray observations by HAWC and LHAASO have presented evidence for multiple Galactic sources that exhibit a spatially extended morphology and have energy spectra continuing beyond 100 TeV. A fraction of such emission could be produced by interactions of accelerated hadronic cosmic rays, resulting in an excess of high-energy neutrinos clustered near these regions. Using 10 years of IceCube data comprising track-like events that originate from charged-current muon neutrino interactions, we perform a dedicated search for extended neutrino sources in the Galaxy. We find no evidence for time-integrated neutrino emission from the potential extended sources studied in the Galactic plane. The most significant location, at 2.6$\sigma$ post-trials, is a 1.7$^\circ$ sized region coincident with the unidentified TeV gamma-ray source 3HWC J1951+266. We provide strong constraints on hadronic emission from several regions in the Galaxy.
Abstract: 2307.07978
Full Text: [ PostScript, PDF]
Full Text: [ PostScript, PDF]
Title:Hadronic nature of high-energy emission from the Galactic Ridge
Download PDFAbstract: We show that the IceCube observation of the Galactic neutrino flux component confirms the hint of detection of neutrinos from the Galactic Ridge (the inner part of the Milky Way disk within the Galactic longitude |l|<30 degrees), previously reported by the ANTARES collaboration. This confirmation indicates that the bulk of the high-energy flux from the Galactic Ridge in multi-TeV band is produced by interactions of high-energy protons and atomic nuclei, rather than electrons. We show that both ANTARES and IceCube measurements agree with the Fermi-LAT telescope measurements of the gamma-ray emission from the Ridge. The multi-messenger (neutrino plus gamma-ray) spectrum of the Ridge over a broad energy range from 10 GeV to 10 TeV is consistent with a model of pion decay emission produced by a power-law distribution of protons with a slope Gamma~2.5, harder than that of the locally observed cosmic ray spectrum. This provides for the first time an unambiguous multi-messenger demonstration of the variability of the spectrum of cosmic rays across the Galactic disk.
Abstract: 2307.08313
Full Text: [ PostScript, PDF]
Full Text: [ PostScript, PDF]
Title:Towards a model of photon-axion conversion in the host galaxy of GRB 221009A
Download PDFAbstract: GRB 221009A was the brightest gamma-ray burst ever detected on Earth. In its early afterglow phase, photons with exceptional energies up to ~18 TeV were observed by LHAASO, and a photon-like air shower of ~251 TeV was detected by Carpet-2. Gamma rays at these high energies can hardly reach us from the distant GRB because of pair production on cosmic background radiation. A number of particle-physics solutions to this problem were discussed in recent months, and one of the most popular ones invokes the mixing of photons with axion-like particles (ALPs). Whether this is a viable scenario, depends crucially on the magnetic fields along the line of sight, which are poorly known. Here, we use the results of recent Hubble Space Telescope observations of the host galaxy of GRB 221009A, combined with magnetic-field measurements and simulations for other galaxies, to construct a toy model of the host-galaxy magnetic field and to estimate the rate of the photon-axion conversion there. Thanks, in particular, to the exceptional edge-on orientation of the host galaxy, strong mixing appears to be natural, both for 18-TeV and 251-TeV photons, for a wide range of ALP parameters.
Abstract: 2307.08464
Full Text: [ PostScript, PDF]
Full Text: [ PostScript, PDF]
Title:Atomic Hydrogen in the Milky Way: A Stepping Stone in the Evolution of Galaxies
Download PDFAbstract: Atomic hydrogen (HI) is a critical stepping stone in the gas evolution cycle of the interstellar medium (ISM) of the Milky Way. Hi traces both the cold, premolecular state before star formation and the warm, diffuse ISM before and after star formation. This review describes new, sensitive HI absorption and emission surveys, which, together with high angular and spectral resolution Hi emission data, have revealed the physical properties of HI, its structure, and its association with magnetic fields. We give an overview of the HI phases and discuss how Hi properties depend on the environment and what its structure can tell us about feedback in the ISM. Key findings include the following: - The mass fraction of the cold neutral medium is $\lesssim 40$\% on average, increasing with $A_V$ due to the increase of mean gas density. - The cold disk extends to at least $R\sim 25$ kpc. - Approximately 40% of the HI is warm, with structural characteristics that derive from feedback events. - Cold HI is highly filamentary, whereas warm HI is more smoothly distributed. We summarize future observational and simulation opportunities that can be used to unravel the 3D structure of the atomic ISM and the effects of heating and cooling on HI properties.
Abstract: 2307.08656
Full Text: [ PostScript, PDF]
Full Text: [ PostScript, PDF]
Title:XMM-Newton observations of the TeV-discovered supernova remnant HESS J1534-571
Download PDFAbstract: We report the results obtained from XMM-Newton observations of the TeV-detected supernova remnant (SNR) HESS J1534-571. We focus on the nature of the cosmic-ray particle content in the SNR, which is revealed by its $\gamma$-ray emission. No signatures of X-ray synchrotron emission were detected from the SNR. This is consistent with earlier results obtained with Suzaku from other regions of the object. A joint modeling of the XMM-Newton and Suzaku spectra yields an upper limit for the total X-ray flux from the SNR area of $\sim$ 5.62$ \times 10^{-13} \ \mathrm{erg\ cm^{-2}\ s^{-1}}$ (95% c.l.) in the energy band of 2-10 keV, for an assumed photon index of 2.0. On the other hand, we do find evidence in the XMM-Newton data for a line-like emission feature at 6.4 keV from localized regions, again confirming earlier Suzaku measurements. We discuss the findings in the context of the origin of the observed $\gamma$-ray emission. Although neither hadronic nor leptonic scenarios can be fully ruled out, the observed line emission can be interpreted as the result of interactions between lower energy ($\sim$ MeV) cosmic-ray protons with high gas density regions in and around HESS J1534-571, and thus potentially be associated with particles accelerated in the SNR.
Abstract: 2307.06896
Full Text: [ PostScript, PDF]
Full Text: [ PostScript, PDF]
Title:Citizen Science in the European Open Science Cloud
Download PDFAbstract: The European Open Science Cloud aims to make all data Findable, Accessible, Interoperable and Reusable. By far the largest community of users of the European Open Science Cloud is the science-inclined public. These users need a more curated experience of open science than subject specialists, but nevertheless make very substantial research contributions in open science, especially in crowdsourced data mining, i.e. citizen science. This short, non-technical invited review presents applications of citizen science in the European Open Science Cloud, with a particular focus on astrophysics and astroparticle physics.
This page created: Thu Jul 20 11:03:05 ACST 2023 by Imogen
For a printable title listing click here
For details on generating this page see the instructions. If there are problems with this page (and I expect there will be from time to time) contact Jose.
For previous lists of abstracts of interest click Previous abstracts of interest