Neutrinos from Microquasars (original) (raw)

Neutrino flux predictions for known galactic microquasars

Nuclear Physics B - Proceedings Supplements, 2003

It has been proposed recently that Galactic microquasars may be prodigious emitters of TeV neutrinos that can be detected by upcoming km 2 neutrino telescopes. In this paper we consider a sample of identified microquasars and microquasar candidates, for which available data enables rough determination of the jet parameters. By employing the parameters inferred from radio observations of various jet ejection events, we determine the neutrino fluxes that should have been produced during these events by photopion production in the jet. Despite the large uncertainties in our analysis, we demonstrate that in several of the sources considered, the neutrino flux at Earth, produced in events similar to those observed, would exceed the detection threshold of a km 2 neutrino detector. The class of microquasars may contain also sources with bulk Lorentz factors larger than those characteristic of the sample considered here, directed along our line of sight. Such sources, which may be very difficult to resolve at radio wavelengths and hence may be difficult to identify as microquasar candidates, may emit neutrinos with fluxes significantly larger than typically obtained in the present analysis. These sources may eventually be identified through their neutrino and gamma-ray emission.

High energy neutrinos from the microquasar SS433

2006

We present a study on the possible emission of high energy neutrinos from the microquasar SS433. These neutrinos are produced by the decay of pions originated via proton-proton interactions in the jets. Neutrino signals observable in neutrino telescopes such as IceCube and NEMO can be obtained with our model, as well as an accompanying gamma-ray signal to be registered by the MAGIC Cherenkov telescope.

Production of gamma rays and neutrinos in the dark jets of the microquasar SS433

Monthly Notices of the Royal Astronomical Society, 2008

We study the spectral energy distribution of gamma rays and neutrinos in the precessing microquasar SS433 as a result of pp interactions within its dark jets. Gamma-ray absorption due to interactions with matter of the extended disk and of the star is found to be important, as well as absorption caused by the UV and mid-IR radiation from the equatorial envelopment. We analyze the range of precessional phases for which this attenuation is at a minimum and the chances for detection of a gamma-ray signal are enhanced. The power of relativistic protons in the jets, a free parameter of the model, is constrained by HEGRA data. This imposes limits on the gamma-ray fluxes to be detected with instruments such as GLAST, VERITAS and MAGIC II. A future detection of high energy neutrinos with cubic kilometer telescopes such as IceCube would also yield important information about acceleration mechanisms that may take place in the dark jets. Overall, the determination of the ratio of gamma-ray to neutrino flux will result in a key observational tool to clarify the physics of heavy jets.

TeV neutrinos from galactic microquasar jets

We discuss the possibility that microquasar jets may be powerful emitters of TeV neutrinos. We estimate the neutrino fluxes produced by photopion production in the jets of a sample of identified microquasars and microquasar candidates, for which available data enables rough determination of the jet parameters. We demonstrate that in several of the sources considered, the neutrino flux at Earth, produced in events similar to those observed, can exceed the detection threshold of a km 2 neutrino detector. Sources with bulk Lorentz factors larger than those characteristic of the sample considered here, directed along our line of sight may be very difficult to resolve at radio wavelengths and hence may be difficult to identify as microqusar candidates. However these sources can be identified through their neutrino and gamma-ray emission.

Probing Microquasars with TeV Neutrinos

Physical Review Letters, 2001

The jets associated with Galactic micro-quasars are believed to be ejected by accreting stellar mass black-holes or neutron stars. We show that if the energy content of the jets in the transient sources is dominated by electron-proton plasma, then a several hour outburst of 1-100 TeV neutrinos produced by photo-meson interactions should precede the radio flares associated with major ejection events. Several neutrinos may be detected during a single outburst by a 1 km 2 detector, thereby providing a powerful probe of micro-quasars jet physics.

Gamma-ray and neutrino emission from misaligned microquasars

Astronomy and Astrophysics, 2005

Microquasars are accreting X-ray binary systems with non-thermal radio jets. In some of these systems the jet is expected to be strongly misaligned with the perpendicular to the orbital plane. If the donor star is an early-type star, the jet could collide with the stellar wind producing a standing shock between the compact object and the stellar surface. Relativistic particles injected by the jet can be re-accelerated and isotropized at the colliding region. If the jet has hadronic content, TeV protons will diffuse into the inner, dense wind leading to gamma-ray and neutrino production from interactions with the matter of the wind. In the case of very powerful jets, the wind pressure can be overbalanced and the jet might impact directly onto the stellar surface. We present estimates of the gamma-ray and neutrino luminosities for different sets of parameters in these scenarios and we briefly discuss the effects of this radiation on the donor star and its detectability with current instruments.

Magnetic field effects on neutrino production in microquasars

Astronomy and Astrophysics, 2009

Aims. We investigate the effects of magnetic fields on neutrino production in microquasars. Methods. We calculate the steady particle distributions for the pions and muons generated in pγ and pp interactions in the jet taking the effects of all energy losses into account. Results. The obtained neutrino emission is significantly modified due to the synchrotron losses suffered by secondary pions and muons. Conclusions. The estimates made for neutrino fluxes arriving on the Earth imply that detection of high-energy neutrinos from the vicinity of the compact object can be difficult. However, in the case of windy microquasars, the interaction of energetic protons in the jet with matter of dense clumps of the wind could produce detectable neutrinos. This is because the pions and muons at larger distances from the compact object will not be affected by synchrotron losses.

Models for Gamma-Ray Production in Low-Mass Microquasars

International Journal of Modern Physics D, 2008

Unlike high-mass gamma-ray binaries, low-mass microquasars lack external sources of radiation and matter that could produce high-energy emission through interactions with relativistic particles. In this work, we consider the synchrotron emission of protons and leptons that populate the jet of a low-mass microquasar. In our model photohadronic and inverse Compton (IC) interactions with synchrotron photons produced by both protons and leptons result in a high-energy tail of the spectrum. We also estimate the contribution from secondary pairs injected through photopair production. The high-energy emission is dominated by radiation of hadronic origin, so we can call these objects "proton microquasars".

The proton low-mass microquasar: high-energy emission

Astronomy & Astrophysics, 2008

Context. A population of unidentified gamma-ray sources is forming a structure resembling a halo around the Galactic center. These sources are highly variable, and hence they should be associated with compact objects. Microquasars are objects undergoing accretion with relativistic jets; if such an object has a low-mass, evolved, donor star, it might be found in the Galactic halo. If these low-mass microquasars can generate detectable gamma-ray emission, then they are natural candidates to account for the halo high-energy sources. Aims. We aim to construct models for high-energy emission of low-mass microquasars, which could produce a significant luminosity in the gamma-ray domain. Methods. We consider that a significant fraction of the relativistic particles in the jets of low-mass microquasars are protons and then we study the production of high-energy emission through proton synchrotron radiation and photopion production. Photopair production and leptonic processes are considered as well. We compute a number of specific models with different parameters to explore the possibilities of this scenario. Results. We find that important luminosities, in the range of 10 34-10 37 erg s −1 , can be achieved by proton synchrotron radiation in the Gamma-Ray Large Area Space Telescope (GLAST) energy range, and lower, but still significant luminosities at higher energies for some models. Conclusions. We conclude that the proton microquasar model offers a very interesting alternative to account for the halo gamma-ray sources and presents a variety of predictions that might be tested in the near future by instruments like GLAST, the High-Energy Stereoscopic System II (HESS II), the Major Atmospheric Gamma-ray Imaging Cherenkov telescope II (MAGIC II), and neutrino telescopes like IceCube.