The ORBITS OF THE Γ-Ray BINARIES LS I +61 303 AND LS 5039

Aragona, Christina; McSwain, M. Virginia; Grundstrom, Erika D.; Marsh, Amber N.; Roettenbacher, Rachael M.; Hessler, Katelyn M.; Boyajian, Tabetha S.; Ray, Paul S.

doi:10.1088/0004-637x/698/1/514

Cited by 140 publications

(209 citation statements)

References 33 publications

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“…The best estimation of the periastron passage phase in this ephemeris is 0.275 (Aragona et al 2009), hence there is an offset of 0.275 between the radio ephemeris used by observers and the one used here. As outlined in Sect.…”

Section: Ls I +61 • 303mentioning

confidence: 85%

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Relativistic Doppler-boosted emission in gamma-ray binaries

Dubus¹,

Cerutti²,

Henri³

2010

A&A

104

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Context. Gamma-ray binaries could be compact pulsar wind nebulae formed when a young pulsar orbits a massive star. The pulsar wind is contained by the stellar wind of the O or Be companion, creating a relativistic comet-like structure accompanying the pulsar along its orbit. Aims. The X-ray and the very high energy (>100 GeV, VHE) gamma-ray emission from the binary LS 5039 are modulated on the orbital period of the system. Maximum and minimum flux occur at the conjunctions of the orbit, suggesting that the explanation is linked to the orbital geometry. The VHE modulation has been proposed to be due to the combined effect of Compton scattering and pair production on stellar photons, both of which depend on orbital phase. The X-ray modulation could be due to relativistic Doppler boosting in the comet tail where both the X-ray and VHE photons would be emitted. Methods. Relativistic aberrations change the seed stellar photon flux in the comoving frame so Doppler boosting affects synchrotron and inverse Compton emission differently. The dependence with orbital phase of relativistic Doppler-boosted (isotropic) synchrotron and (anisotropic) inverse Compton emission is calculated, assuming that the flow is oriented radially away from the star (LS 5039) or tangentially to the orbit (LS I +61 • 303, PSR B1259-63).Results. Doppler boosting of the synchrotron emission in LS 5039 produces a lightcurve whose shape corresponds to the X-ray modulation. The observations imply an outflow velocity of 0.15-0.33c consistent with the expected flow speed at the pulsar wind termination shock. In LS I +61 • 303, the calculated Doppler boosted emission peaks in phase with the observed VHE and X-ray maximum. Conclusions. Doppler boosting is not negligible in gamma-ray binaries, even for mildly relativistic speeds. The boosted modulation reproduces the X-ray modulation in LS 5039 and could also provide an explanation for the puzzling phasing of the VHE peak in LS I +61 • 303.

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Section: Ls I +61 • 303mentioning

confidence: 85%

“…Full calculations were also carried out for LS 5039 and LS I +61 • 303. The orbital parameters are taken from Manchester et al (1995) for PSR B1259-63 and from Aragona et al (2009) …”

Section: Discussionmentioning

confidence: 99%

Relativistic Doppler-boosted emission in gamma-ray binaries

Dubus¹,

Cerutti²,

Henri³

2010

A&A

104

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“…The orbital parameters of LS 5039 such as the eccentricity, masses, and orbit inclination are not well constrained or are still under discussion (Casares et al 2005;Aragona et al 2009;Sarty et al 2011). The proper motion and the space velocity of the source were first determined in Ribó et al (2002).…”

Section: The Gamma-ray Binary Ls 5039mentioning

confidence: 99%

On the origin of LS 5039 and PSR J1825−1446

Moldón

Ribó

Paredes

et al. 2012

A&A

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Context. The gamma-ray binary LS 5039 and the isolated pulsar PSR J1825−1446 were proposed to have been formed in the supernova remnant (SNR) G016.8−01.1. Aims. We aim to obtain the Galactic trajectory of LS 5039 and PSR J1825−1446 to find their origin in the Galaxy, and in particular to check their association with SNR G016.8−01.1 to restrict their age. Methods. By means of radio and optical observations we obtained the proper motion and the space velocity of the sources. Results. The proper motion of PSR J1825−1446 corresponds to a transverse space velocity of 690 km s −1 at a distance of 5 kpc. Its Galactic velocity at different distances is not compatible with the expected Galactic rotation. The velocity and characteristic age of PSR J1825−1446 make it incompatible with SNR G016.8−01.1. There are no clear OB associations or SNRs crossing the past trajectory of PSR J1825−1446. We estimate the age of the pulsar to be 80-245 kyr, which is compatible with its characteristic age. The proper motion of LS 5039 is μ α cos δ = 7.09 and μ δ = −8.82 mas yr −1 . The association of LS 5039 with SNR G016.8−01.1 is unlikely, although we cannot discard it. The system would have had to be formed in the association Ser OB2 (at 2.0 kpc) if the age of the system is 1.0-1.2 Myr, or in the association Sct OB3 (distance 1.5-2 kpc) for an age of 0.1-0.2 Myr. If the system were not formed close to Ser OB2, the pseudo-synchronization of the orbit would be unlikely. Conclusions. PSR J1825−1446 is a high-velocity isolated pulsar ejected from the Galaxy. The distance to LS 5039, which needs to be constrained by future astrometric missions such as Gaia, is a key parameter for restricting its origin and age.

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“…The Be star with a fast polar wind has an equatorial dense, low velocity wind with a power law density distribution of the form ρ w (R) = ρ 0 (R/R * ) −3 , where R * is the radius of the primary Be star (Waters et al 1988;Martí & Paredes 1995). The real nature of the compact object travelling in this stratified wind on an eccentric orbit with e = 0.54-0.7 is still unknown (Aragona et al 2009;Casares et al 2005). In fact, because of the uncertainty in the inclination of the orbit i = 30 • ± 20 • , the compact object could be either a neutron star or a black hole of 3-4 M .…”

Section: Ls I +61mentioning

confidence: 99%

Feasibility study of Lense-Thirring precession in LS I +61°303

Massi

Zimmermann

2010

A&A

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Context. Very recent analysis of the radio spectral index and high energy observations have shown that the two-peak accretion/ejection microquasar model applies for LS I +61 • 303. Aims. The fast variations of the position angle observed with MERLIN and confirmed by consecutive VLBA images must therefore be explained in the context of the microquasar scenario. Methods.We calculate what could be the precessional period for the accretion disk in LS I +61 • 303 under tidal forces of the Be star (P tidal−forces ) or under the effect of frame dragging produced by the rotation of the compact object (P Lense−Thirring ). Results. P tidal−forces is more than one year. P Lense−Thirring depends on the truncated radius of the accretion disk, R tr . We determined R tr = 300r g for observed QPO at 2 Hz. This value is much above the few r g , where the Bardeen-Petterson effect should align the midplane of the disk. For this truncated radius of the accretion disk P Lense−Thirring for a slow rotator results in a few days. Conclusions. Lense-Thirring precession induced by a slowly rotating compact object could be compatible with the daily variations of the ejecta angle observed in LS I +61 • 303.

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The ORBITS OF THE Γ-Ray BINARIES LS I +61 303 AND LS 5039

Cited by 140 publications

References 33 publications

Relativistic Doppler-boosted emission in gamma-ray binaries

Relativistic Doppler-boosted emission in gamma-ray binaries

On the origin of LS 5039 and PSR J1825−1446

Feasibility study of Lense-Thirring precession in LS I +61°303

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