If axions exist, they are copiously produced in hot and dense plasmas, carrying away energy direc... more If axions exist, they are copiously produced in hot and dense plasmas, carrying away energy directly from the interior of stars. Various astronomical observables constrain the operation of such anomalous stellar energy-loss channels and thus provide restrictive limits on the axion interactions with photons, nucleons, and electrons. In typical axion models a limit ma < ∼ 10 −2 eV is implied. The main arguments leading to this result are explained, including more recent work on the important supernova 1987A constraint.
Nonstandard neutrino properties (masses, mixing, sterile states, electromagnetic interactions, an... more Nonstandard neutrino properties (masses, mixing, sterile states, electromagnetic interactions, and so forth) can have far-reaching ramifications in astrophysics and cosmology. We look at the most interesting cases in the light of the powerful current indications for neutrino oscillations.
Axion emission by hot and dense plasmas is a new energy-loss channel for stars. Observational con... more Axion emission by hot and dense plasmas is a new energy-loss channel for stars. Observational consequences include a modification of the solar sound-speed profile, an increase of the solar neutrino flux, a reduction of the helium-burning lifetime of globular-cluster stars, accelerated white-dwarf cooling, and a reduction of the supernova SN 1987A neutrino burst duration. We review and update these arguments and summarize the resulting axion constraints.
The case for small neutrino mass differences from atmospheric and solar neutrino oscillation expe... more The case for small neutrino mass differences from atmospheric and solar neutrino oscillation experiments has become compelling, but leaves the overall neutrino mass scale m ν undetermined. The most restrictive limit of m ν < 0.8 eV arises from the 2dF galaxy redshift survey in conjunction with the standard theory of cosmological structure formation. A relation between the hot dark matter fraction and m ν depends on the cosmic number density n ν of neutrinos. If solar neutrino oscillations indeed correspond to the favored large mixing angle MSW solution, then big-bang nucleosynthesis gives us a restrictive limit on all neutrino chemical potentials, removing the previous uncertainty of n ν. Therefore, a possible future measurement of m ν will directly establish the cosmic neutrino mass fraction Ω ν. Cosmological neutrinos with sub-eV masses can play an interesting role for producing the highest-energy cosmic rays (Z-burst scenario). Sub-eV masses also relate naturally to leptogenesis scenarios of the cosmic baryon asymmetry. Unfortunately, the time-of-flight dispersion of a galactic or local-group supernova neutrino burst is not sensitive in the sub-eV range.
Annual Review of Nuclear and Particle Science, 1999
▪ Low-mass particles, such as neutrinos, axions, other Nambu-Goldstone bosons, and gravitons, a... more ▪ Low-mass particles, such as neutrinos, axions, other Nambu-Goldstone bosons, and gravitons, are produced in the hot and dense interior of stars. Therefore, astrophysical arguments constrain the properties of these particles in ways that are often complementary to cosmological arguments and to laboratory experiments. This review provides an update on the most important stellar-evolution limits and discusses them in the context of other information from cosmology and laboratory experiments.
The hot and dense core formed in the collapse of a massive star is a powerful source of hypotheti... more The hot and dense core formed in the collapse of a massive star is a powerful source of hypothetical feebly-interacting particles such as sterile neutrinos, dark photons, axion-like particles (ALPs), and others. Radiative decays such as a → 2γ deposit this energy in the surrounding material if the mean free path is less than the radius of the progenitor star. For the first time, we use a supernova (SN) population with particularly low explosion energies as the most sensitive calorimeters to constrain this possibility. These SNe are observationally identified as low-luminosity events with low ejecta velocities and low masses of ejected 56 Ni. Their low energies limit the energy deposition from particle decays to less than about 0.1 B, where 1 B (bethe) = 10 51 erg. For 1-500 MeV-mass ALPs, this generic argument excludes ALP-photon couplings Gaγγ in the 10 −10-10 −8 GeV −1 range.
Collection of "Extended Abstracts" of talks presented at the SFB-375 workshop NEUTRINO ... more Collection of "Extended Abstracts" of talks presented at the SFB-375 workshop NEUTRINO ASTROPHYSICS, Ringberg Castle, Tegernsee, Germany, 20-24 Oct. 1997. Topics include Solar Neutrinos, Supernovae, Gamma-Ray Bursts, High-Energy Neutrinos (atmospheric, astrophysical), Cosmology, and Future Prospects. The focus is on astrophysical and experimental/observational aspects of astrophysical neutrinos while particle theory and neutrino laboratory experiments are not covered
Abstract. Recent developments of those areas of astro-particle physics are discussed that were re... more Abstract. Recent developments of those areas of astro-particle physics are discussed that were represented at the HEP97 conference. In particular, the current status of direct and indirect dark-matter searches and of TeV neutrino and γ-ray astronomy will be reviewed. 1
We review some recent determinations of the amount of dark matter on galactic and larger scales, ... more We review some recent determinations of the amount of dark matter on galactic and larger scales, with special attention to the dark matter in the Milky Way. We then briefly review the motivation for and basic physics of several dark matter candidates, and then go into more depth for two candidates, the neutralino from supersymmetry, and the baryonic Macho candidate. We give some motivation for supersymmetry and review neutralino detection strategies. For Machos we give a description of the discovery of Machos via gravitational microlensing and the interpretation of the results with respect to the dark matter problem.
Axion emission by hot and dense plasmas is a new energy-loss channel for stars. Observational con... more Axion emission by hot and dense plasmas is a new energy-loss channel for stars. Observational consequences include a modification of the solar sound-speed profile, an increase of the solar neutrino flux, a reduction of the helium-burning lifetime of globular-cluster stars, accelerated white-dwarf cooling, and a reduction of the supernova SN 1987A neutrino burst duration. We review and update these arguments and summarize the resulting axion constraints.
Collection of "Extended Abstracts" of talks presented at the SFB-375 workshop NEUTRINO ... more Collection of "Extended Abstracts" of talks presented at the SFB-375 workshop NEUTRINO ASTROPHYSICS, Ringberg Castle, Tegernsee, Germany, 20-24 Oct. 1997. Topics include Solar Neutrinos, Supernovae, Gamma-Ray Bursts, High-Energy Neutrinos (atmospheric, astrophysical), Cosmology, and Future Prospects. The focus is on astrophysical and experimental/observational aspects of astrophysical neutrinos while particle theory and neutrino laboratory experiments are not covered.
Journal of Physics G: Nuclear and Particle Physics, 2016
An illustration of the correlation between Σ ν and | m ee | (left panel) and that between Σ ν and... more An illustration of the correlation between Σ ν and | m ee | (left panel) and that between Σ ν and m e (right panel) by using the 3σ inputs as given in Table 1.1. Here the red (blue) region corresponds to the normal (inverted) neutrino mass ordering.. 1-3 Location of the JUNO site. The distances to the nearby Yangjiang NPP and Taishan NPP are both 53 km. Daya Bay NPP is 215 km away. Huizhou and Lufeng NPPs have not been approved yet. Three metropolises,
The role of neutrinos in stars is introduced for students with little prior astrophysical exposur... more The role of neutrinos in stars is introduced for students with little prior astrophysical exposure. We begin with neutrinos as an energy-loss channel in ordinary stars and conversely, how stars provide information on neutrinos and possible other low-mass particles. Next we turn to the Sun as a measurable source of neutrinos and other particles. Finally we discuss supernova (SN) neutrinos, the SN 1987A measurements, and the quest for a high-statistics neutrino measurement from the next nearby SN. We also touch on the subject of neutrino oscillations in the high-density SN context.
The experimental and astrophysical status of neutrino masses is reviewed with an emphasis on the ... more The experimental and astrophysical status of neutrino masses is reviewed with an emphasis on the cosmologically interesting regime.
Journal of Cosmology and Astroparticle Physics, 2015
We study the potential of a future, large-volume photometric survey to constrain the axion mass m... more We study the potential of a future, large-volume photometric survey to constrain the axion mass m a in the hot dark matter limit. Future surveys such as Euclid will have significantly more constraining power than current observations for hot dark matter. Nonetheless, the lowest accessible axion masses are limited by the fact that axions lighter than ∼ 0.15 eV decouple before the QCD epoch, assumed here to occur at a temperature T QCD ∼ 170 MeV; this leaves an axion population of such low density that its late-time cosmological impact is negligible. For larger axion masses, m a 0.15 eV, where axions remain in equilibrium until after the QCD phase transition, we find that a Euclid-like survey combined with Planck CMB data can detect m a at very high significance. Our conclusions are robust against assumptions about prior knowledge of the neutrino mass. Given that the proposed IAXO solar axion search is sensitive to m a 0.2 eV, the axion mass range probed by cosmology is nicely complementary.
Stars are powerful sources for weakly interacting particles that are produced by nuclear or plasm... more Stars are powerful sources for weakly interacting particles that are produced by nuclear or plasma processes in their hot interior. These fluxes can be used for direct measurements (e.g. solar or supernova neutrinos) or the back-reaction on the star can be used to derive limits on new particles. We discuss two examples of current interest, the search for solar axions by the CAST experiment at CERN and stellar-evolution limits on the size of putative large extra dimensions.
Low-mass particles such as neutrinos, axions, other Nambu-Goldstone bosons, gravitons, and so for... more Low-mass particles such as neutrinos, axions, other Nambu-Goldstone bosons, gravitons, and so forth are produced in the hot and dense interior of stars. Therefore, astrophysical arguments constrain the properties of these particles in ways which are often complementary to cosmological arguments and to laboratory experiments. The most important stellar-evolution arguments are explained and the resulting particle-physics limits are reviewed in the context of other information from cosmology and laboratory experiments. Other cases may be different in detail, but it appears safe to assume that any new energy-loss channel must not exceed something like 10% of L ⊙ .
The neutrino emission characteristics of the first full-scale three-dimensional supernova simulat... more The neutrino emission characteristics of the first full-scale three-dimensional supernova simulations with sophisticated three-flavor neutrino transport for three models with masses 11.2, 20 and 27 M are evaluated in detail. All the studied progenitors show the expected hydrodynamical instabilities in the form of large-scale convective overturn. In addition, the recently identified LESA phenomenon (lepton-number emission self-sustained asymmetry) is generic for all our cases. Pronounced SASI (standing accretion-shock instability) activity appears in the 20 and 27 M cases, partly in the form of a spiral mode, inducing large but direction and flavor-dependent modulations of neutrino emission. These modulations can be clearly identified in the existing IceCube and future Hyper-Kamiokande detectors, depending on distance and detector location relative to the main SASI sloshing direction.
If axions exist, they are copiously produced in hot and dense plasmas, carrying away energy direc... more If axions exist, they are copiously produced in hot and dense plasmas, carrying away energy directly from the interior of stars. Various astronomical observables constrain the operation of such anomalous stellar energy-loss channels and thus provide restrictive limits on the axion interactions with photons, nucleons, and electrons. In typical axion models a limit ma < ∼ 10 −2 eV is implied. The main arguments leading to this result are explained, including more recent work on the important supernova 1987A constraint.
Nonstandard neutrino properties (masses, mixing, sterile states, electromagnetic interactions, an... more Nonstandard neutrino properties (masses, mixing, sterile states, electromagnetic interactions, and so forth) can have far-reaching ramifications in astrophysics and cosmology. We look at the most interesting cases in the light of the powerful current indications for neutrino oscillations.
Axion emission by hot and dense plasmas is a new energy-loss channel for stars. Observational con... more Axion emission by hot and dense plasmas is a new energy-loss channel for stars. Observational consequences include a modification of the solar sound-speed profile, an increase of the solar neutrino flux, a reduction of the helium-burning lifetime of globular-cluster stars, accelerated white-dwarf cooling, and a reduction of the supernova SN 1987A neutrino burst duration. We review and update these arguments and summarize the resulting axion constraints.
The case for small neutrino mass differences from atmospheric and solar neutrino oscillation expe... more The case for small neutrino mass differences from atmospheric and solar neutrino oscillation experiments has become compelling, but leaves the overall neutrino mass scale m ν undetermined. The most restrictive limit of m ν < 0.8 eV arises from the 2dF galaxy redshift survey in conjunction with the standard theory of cosmological structure formation. A relation between the hot dark matter fraction and m ν depends on the cosmic number density n ν of neutrinos. If solar neutrino oscillations indeed correspond to the favored large mixing angle MSW solution, then big-bang nucleosynthesis gives us a restrictive limit on all neutrino chemical potentials, removing the previous uncertainty of n ν. Therefore, a possible future measurement of m ν will directly establish the cosmic neutrino mass fraction Ω ν. Cosmological neutrinos with sub-eV masses can play an interesting role for producing the highest-energy cosmic rays (Z-burst scenario). Sub-eV masses also relate naturally to leptogenesis scenarios of the cosmic baryon asymmetry. Unfortunately, the time-of-flight dispersion of a galactic or local-group supernova neutrino burst is not sensitive in the sub-eV range.
Annual Review of Nuclear and Particle Science, 1999
▪ Low-mass particles, such as neutrinos, axions, other Nambu-Goldstone bosons, and gravitons, a... more ▪ Low-mass particles, such as neutrinos, axions, other Nambu-Goldstone bosons, and gravitons, are produced in the hot and dense interior of stars. Therefore, astrophysical arguments constrain the properties of these particles in ways that are often complementary to cosmological arguments and to laboratory experiments. This review provides an update on the most important stellar-evolution limits and discusses them in the context of other information from cosmology and laboratory experiments.
The hot and dense core formed in the collapse of a massive star is a powerful source of hypotheti... more The hot and dense core formed in the collapse of a massive star is a powerful source of hypothetical feebly-interacting particles such as sterile neutrinos, dark photons, axion-like particles (ALPs), and others. Radiative decays such as a → 2γ deposit this energy in the surrounding material if the mean free path is less than the radius of the progenitor star. For the first time, we use a supernova (SN) population with particularly low explosion energies as the most sensitive calorimeters to constrain this possibility. These SNe are observationally identified as low-luminosity events with low ejecta velocities and low masses of ejected 56 Ni. Their low energies limit the energy deposition from particle decays to less than about 0.1 B, where 1 B (bethe) = 10 51 erg. For 1-500 MeV-mass ALPs, this generic argument excludes ALP-photon couplings Gaγγ in the 10 −10-10 −8 GeV −1 range.
Collection of "Extended Abstracts" of talks presented at the SFB-375 workshop NEUTRINO ... more Collection of "Extended Abstracts" of talks presented at the SFB-375 workshop NEUTRINO ASTROPHYSICS, Ringberg Castle, Tegernsee, Germany, 20-24 Oct. 1997. Topics include Solar Neutrinos, Supernovae, Gamma-Ray Bursts, High-Energy Neutrinos (atmospheric, astrophysical), Cosmology, and Future Prospects. The focus is on astrophysical and experimental/observational aspects of astrophysical neutrinos while particle theory and neutrino laboratory experiments are not covered
Abstract. Recent developments of those areas of astro-particle physics are discussed that were re... more Abstract. Recent developments of those areas of astro-particle physics are discussed that were represented at the HEP97 conference. In particular, the current status of direct and indirect dark-matter searches and of TeV neutrino and γ-ray astronomy will be reviewed. 1
We review some recent determinations of the amount of dark matter on galactic and larger scales, ... more We review some recent determinations of the amount of dark matter on galactic and larger scales, with special attention to the dark matter in the Milky Way. We then briefly review the motivation for and basic physics of several dark matter candidates, and then go into more depth for two candidates, the neutralino from supersymmetry, and the baryonic Macho candidate. We give some motivation for supersymmetry and review neutralino detection strategies. For Machos we give a description of the discovery of Machos via gravitational microlensing and the interpretation of the results with respect to the dark matter problem.
Axion emission by hot and dense plasmas is a new energy-loss channel for stars. Observational con... more Axion emission by hot and dense plasmas is a new energy-loss channel for stars. Observational consequences include a modification of the solar sound-speed profile, an increase of the solar neutrino flux, a reduction of the helium-burning lifetime of globular-cluster stars, accelerated white-dwarf cooling, and a reduction of the supernova SN 1987A neutrino burst duration. We review and update these arguments and summarize the resulting axion constraints.
Collection of "Extended Abstracts" of talks presented at the SFB-375 workshop NEUTRINO ... more Collection of "Extended Abstracts" of talks presented at the SFB-375 workshop NEUTRINO ASTROPHYSICS, Ringberg Castle, Tegernsee, Germany, 20-24 Oct. 1997. Topics include Solar Neutrinos, Supernovae, Gamma-Ray Bursts, High-Energy Neutrinos (atmospheric, astrophysical), Cosmology, and Future Prospects. The focus is on astrophysical and experimental/observational aspects of astrophysical neutrinos while particle theory and neutrino laboratory experiments are not covered.
Journal of Physics G: Nuclear and Particle Physics, 2016
An illustration of the correlation between Σ ν and | m ee | (left panel) and that between Σ ν and... more An illustration of the correlation between Σ ν and | m ee | (left panel) and that between Σ ν and m e (right panel) by using the 3σ inputs as given in Table 1.1. Here the red (blue) region corresponds to the normal (inverted) neutrino mass ordering.. 1-3 Location of the JUNO site. The distances to the nearby Yangjiang NPP and Taishan NPP are both 53 km. Daya Bay NPP is 215 km away. Huizhou and Lufeng NPPs have not been approved yet. Three metropolises,
The role of neutrinos in stars is introduced for students with little prior astrophysical exposur... more The role of neutrinos in stars is introduced for students with little prior astrophysical exposure. We begin with neutrinos as an energy-loss channel in ordinary stars and conversely, how stars provide information on neutrinos and possible other low-mass particles. Next we turn to the Sun as a measurable source of neutrinos and other particles. Finally we discuss supernova (SN) neutrinos, the SN 1987A measurements, and the quest for a high-statistics neutrino measurement from the next nearby SN. We also touch on the subject of neutrino oscillations in the high-density SN context.
The experimental and astrophysical status of neutrino masses is reviewed with an emphasis on the ... more The experimental and astrophysical status of neutrino masses is reviewed with an emphasis on the cosmologically interesting regime.
Journal of Cosmology and Astroparticle Physics, 2015
We study the potential of a future, large-volume photometric survey to constrain the axion mass m... more We study the potential of a future, large-volume photometric survey to constrain the axion mass m a in the hot dark matter limit. Future surveys such as Euclid will have significantly more constraining power than current observations for hot dark matter. Nonetheless, the lowest accessible axion masses are limited by the fact that axions lighter than ∼ 0.15 eV decouple before the QCD epoch, assumed here to occur at a temperature T QCD ∼ 170 MeV; this leaves an axion population of such low density that its late-time cosmological impact is negligible. For larger axion masses, m a 0.15 eV, where axions remain in equilibrium until after the QCD phase transition, we find that a Euclid-like survey combined with Planck CMB data can detect m a at very high significance. Our conclusions are robust against assumptions about prior knowledge of the neutrino mass. Given that the proposed IAXO solar axion search is sensitive to m a 0.2 eV, the axion mass range probed by cosmology is nicely complementary.
Stars are powerful sources for weakly interacting particles that are produced by nuclear or plasm... more Stars are powerful sources for weakly interacting particles that are produced by nuclear or plasma processes in their hot interior. These fluxes can be used for direct measurements (e.g. solar or supernova neutrinos) or the back-reaction on the star can be used to derive limits on new particles. We discuss two examples of current interest, the search for solar axions by the CAST experiment at CERN and stellar-evolution limits on the size of putative large extra dimensions.
Low-mass particles such as neutrinos, axions, other Nambu-Goldstone bosons, gravitons, and so for... more Low-mass particles such as neutrinos, axions, other Nambu-Goldstone bosons, gravitons, and so forth are produced in the hot and dense interior of stars. Therefore, astrophysical arguments constrain the properties of these particles in ways which are often complementary to cosmological arguments and to laboratory experiments. The most important stellar-evolution arguments are explained and the resulting particle-physics limits are reviewed in the context of other information from cosmology and laboratory experiments. Other cases may be different in detail, but it appears safe to assume that any new energy-loss channel must not exceed something like 10% of L ⊙ .
The neutrino emission characteristics of the first full-scale three-dimensional supernova simulat... more The neutrino emission characteristics of the first full-scale three-dimensional supernova simulations with sophisticated three-flavor neutrino transport for three models with masses 11.2, 20 and 27 M are evaluated in detail. All the studied progenitors show the expected hydrodynamical instabilities in the form of large-scale convective overturn. In addition, the recently identified LESA phenomenon (lepton-number emission self-sustained asymmetry) is generic for all our cases. Pronounced SASI (standing accretion-shock instability) activity appears in the 20 and 27 M cases, partly in the form of a spiral mode, inducing large but direction and flavor-dependent modulations of neutrino emission. These modulations can be clearly identified in the existing IceCube and future Hyper-Kamiokande detectors, depending on distance and detector location relative to the main SASI sloshing direction.
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Papers by Georg Raffelt