GeV emission of gamma-ray binary with pulsar scenario

ABSTRACT We study GeV emission from gamma-ray binaries by assuming that the compact object is a young pulsar. We assume that the relativistic unshocked pulsar wind with a Lorentz factor of 104–5 can produce the GeV emission by the inverse-Compton scattering process in the dense soft-photon field of the companion star. The travel distance of the unshocked pulsar wind that moves toward the observer depends on the orbital phase of the pulsar. We discuss that the orbital modulation of the GeV emission is a result of combination of the effects of the travel distance of the unshocked pulsar wind and of the anisotropic soft-photon field of the companion star. In this paper, we study how the effect of the travel distance of the unshocked pulsar wind affects to the orbital modulation of GeV emission. We apply our scenario to two gamma-ray binaries, LMC P3 and 4FGL J1405.1−6119. We find that with the suggested system parameters of LMC P3, the observed amplitude of the orbital modulation and the peak width are more consistent with the model light curve by taking into account the effect of the travel distance. For LMC P3, we analyse the GeV spectrum with 8-yr Fermi-LAT data and discuss the broadband emission process in X-ray to TeV energy bands. We predict a possible system geometry for 4FGL J1405.1−6119 by fitting the GeV light curve.

Download Full-text

Extension of an exponential light-curve gamma-ray burst pulse model across energy bands

Monthly Notices of the Royal Astronomical Society ◽

10.1111/j.1365-2966.2011.19838.x ◽

2011 ◽

Vol 419 (2) ◽

pp. 1650-1659 ◽

Cited By ~ 7

Author(s):

Robert J. Nemiroff

Keyword(s):

Light Curve ◽

Gamma Ray ◽

Energy Bands ◽

Gamma Ray Burst ◽

Burst Pulse

Download Full-text

Mass and Orbit Constraints of the Gamma-ray Binary LS 5039

Proceedings of the International Astronomical Union ◽

10.1017/s1743921311027761 ◽

2011 ◽

Vol 7 (S282) ◽

pp. 331-332

Author(s):

T. Szalai ◽

G. E. Sarty ◽

L. L. Kiss ◽

J. M. Matthews ◽

J. Vinkó ◽

...

Keyword(s):

Light Curve ◽

Orbital Period ◽

Gamma Ray ◽

Broad Band ◽

Compact Object ◽

Physical Parameters ◽

Photometric Variability ◽

Γ Ray

AbstractWe present the results of space-based photometric and ground-based spectroscopic observing campaigns on the γ-ray binary LS 5039. The new orbital and physical parameters of the system are similar to former results, except we found a lower eccentricity. Our MOST-data show that any broad-band optical photometric variability at the orbital period is below the 2 mmag level. Light curve simulations support the lower value of eccentricity and imply that the mass of the compact object is higher than 1.8 M⊙.

Download Full-text

X-ray and UV emission of the ultrashort-period, low-mass eclipsing binary system BX Trianguli

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834116 ◽

2018 ◽

Vol 619 ◽

pp. A138

Author(s):

V. Perdelwitz ◽

S. Czesla ◽

J. Robrade ◽

T. Pribulla ◽

J. H. M. M. Schmitt

Keyword(s):

Binary System ◽

Light Curve ◽

Binary Systems ◽

Uv Light ◽

Close Binary ◽

Eclipsing Binary ◽

X Ray ◽

Uv Emission ◽

Low Mass ◽

Orbital Modulation

Context.Close binary systems provide an excellent tool for determining stellar parameters such as radii and masses with a high degree of precision. Due to the high rotational velocities, most of these systems exhibit strong signs of magnetic activity, postulated to be the underlying reason for radius inflation in many of the components. Aims.We extend the sample of low-mass binary systems with well-known X-ray properties. Methods.We analyze data from a singular XMM-Newton pointing of the close, low-mass eclipsing binary system BX Tri. The UV light curve was modeled with the eclipsing binary modeling tool PHOEBE and data acquired with the EPIC cameras was analyzed to search for hints of orbital modulation. Results.We find clear evidence of orbital modulation in the UV light curve and show that PHOEBE is fully capable of modeling data within this wavelength range. Comparison to a theoretical flux prediction based on PHOENIX models shows that the majority of UV emission is of photospheric origin. While the X-ray light curve does exhibit strong variations, the signal-to-noise ratio of the observation is insufficient for a clear detection of signs of orbital modulation. There is evidence of a Neupert-like correlation between UV and X-ray data.

Download Full-text

Introducing the HD+B model for pulsar wind nebulae: a hybrid hydrodynamics/radiative approach

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa1052 ◽

2020 ◽

Vol 494 (3) ◽

pp. 4357-4370

Author(s):

B Olmi ◽

D F Torres

Keyword(s):

Gamma Ray ◽

High Energy ◽

Theoretical Modelling ◽

X Rays ◽

Pulsar Wind Nebulae ◽

New Approach ◽

Energy Gamma ◽

Radiative Model ◽

Pulsar Wind

ABSTRACT Identification and characterization of a rapidly increasing number of pulsar wind nebulae is, and will continue to be, a challenge of high-energy gamma-ray astrophysics. Given that such systems constitute -by far- the most numerous expected population in the TeV regime, such characterization is important not only to learn about the sources per se from an individual and population perspective, but also to be able to connect them with observations at other frequencies, especially in radio and X-rays. Also, we need to remove the emission from nebulae in highly confused regions of the sky for revealing other underlying emitters. In this paper, we present a new approach for theoretical modelling of pulsar wind nebulae: a hybrid hydrodynamic-radiative model able to reproduce morphological features and spectra of the sources, with relatively limited numerical cost.

Download Full-text

The dynamic ejecta of compact object mergers and eccentric collisions

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2012.0272 ◽

2013 ◽

Vol 371 (1992) ◽

pp. 20120272 ◽

Cited By ~ 58

Author(s):

Stephan Rosswog

Keyword(s):

Globular Clusters ◽

Gamma Ray ◽

Ambient Medium ◽

Compact Object ◽

Solar Mass ◽

Abundance Pattern ◽

Compact Binary ◽

Hydrodynamical Simulations ◽

Rich Material ◽

R Process

Compact object mergers eject neutron-rich matter in a number of ways: by the dynamical ejection mediated by gravitational torques, as neutrino-driven winds, and probably also a good fraction of the resulting accretion disc finally becomes unbound by a combination of viscous and nuclear processes. If compact binary mergers indeed produce gamma-ray bursts, there should also be an interaction region where an ultra-relativistic outflow interacts with the neutrino-driven wind and produces moderately relativistic ejecta. Each type of ejecta has different physical properties, and therefore plays a different role for nucleosynthesis and for the electromagnetic (EM) transients that go along with compact object encounters. Here, we focus on the dynamic ejecta and present results for over 30 hydrodynamical simulations of both gravitational wave-driven mergers and parabolic encounters as they may occur in globular clusters. We find that mergers eject approximately 1 per cent of a Solar mass of extremely neutron-rich material. The exact amount, as well as the ejection velocity, depends on the involved masses with asymmetric systems ejecting more material at higher velocities. This material undergoes a robust r-process and both ejecta amount and abundance pattern are consistent with neutron star mergers being a major source of the ‘heavy’ ( A >130) r-process isotopes. Parabolic collisions, especially those between neutron stars and black holes, eject substantially larger amounts of mass, and therefore cannot occur frequently without overproducing gala- ctic r-process matter. We also discuss the EM transients that are powered by radioactive decays within the ejecta (‘macronovae’), and the radio flares that emerge when the ejecta dissipate their large kinetic energies in the ambient medium.

Download Full-text