Modelling the correlated keV/TeV light curves of Be/gamma-ray binaries

Chen, A. M.; Takata, Jumpei

doi:10.1051/0004-6361/202142258

Cited by 7 publications

(15 citation statements)

References 128 publications

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“…It is worth noting, that the derived position of the periastron of LS I +61303 is from the orbital solutions of Casares et al (2005) and Aragona et al (2009), based on the radial velocities. Some recent models by Kravtsov et al (2020) and Chen & Takata (2022) cast doubts on the position of the periastron. However, the radial velocity measurements are model independent and more reliable.…”

Section: Discussionmentioning

confidence: 99%

Optical spectroscopy of the Be/black hole binary MWC 656 ‐ interaction of a black hole with a circumstellar disc

et al. 2022

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We present new spectroscopic observations of the Be/black hole binary MWC 656 obtained during the period 2015–2021. We measure the equivalent width of Hα (EWα), Hβ (EWβ$$ {EW}_{\beta } $$), and the distance between the peaks of Hα (normalΔVα$$ \Delta {V}_{\alpha } $$), Hβ (normalΔVβ$$ \Delta {V}_{\beta } $$), and FeII (normalΔVFeII$$ \Delta {V}_{\mathrm{FeII}} $$) lines. Combining new and old data, we find that: (1) the density of the circumstellar disc of MWC 656 (normalΔVα$$ \Delta {V}_{\alpha } $$ versus EWα$$ {EW}_{\alpha } $$ diagram) is similar to the Be stars. For the Be stars, we find the relation normalΔVβ=0.999normalΔVα+62.4$$ \Delta {V}_{\beta }=0.999\Delta {V}_{\alpha }+62.4 $$ km s−1, and the position of MWC 656 corresponds to the average behavior of the Be stars. This means that the presence of the black hole does not change the overall structure of the circumstellar disc; (2) the periodogram analysis indicates modulation of EWα$$ {EW}_{\alpha } $$ with a period 60.4±0.4$$ 60.4\pm 0.4 $$ days, which is identical to the binary orbital period. The maxima of EWα$$ {EW}_{\alpha } $$ and EWβ$$ {EW}_{\beta } $$ are around periastron (phase zero); (3) around orbital phase zero, normalΔVβ$$ \Delta {V}_{\beta } $$ and normalΔVFeII$$ \Delta {V}_{FeII} $$ decrease by about 30$$ 30 $$ km s−1. This suggests that we observe an increase of the circumstellar disc size induced by the periastron passage of the black hole and that the entire circumstellar disc pulsates with the orbital period with relative amplitude of 10–20%. The observations also indicate, that the reason for the black hole in MWC 656 to be in deep quiescence is a very low efficiency of accretion (∼2×10−6$$ \sim 2\times {10}^{-6} $$).

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Section: Discussionmentioning

confidence: 99%

Optical spectroscopy of the Be/black hole binary MWC 656 ‐ interaction of a black hole with a circumstellar disc

et al. 2022

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“…The optical orbits of Casares et al (2012) and Moritani et al (2015) are incompatible with a shockemission scenario as noted by Chen & Takata (2022). Thus they are inadequate for an IBS study of J0632.…”

Section: Orbital Solutions For J0632mentioning

confidence: 95%

“…X-ray LC data provide alternate orbital solutions to those obtained with optical data. Two such solutions are obtained by attributing the bumps in the X-ray LC to disk interactions (Malyshev et al 2019;Chen & Takata 2022). Most recently, Tokayer et al (2021) derived an orbit of J0632 by modeling the most extensive X-ray LC data with an IBS model (Fig.…”

Section: Orbital Solutions For J0632mentioning

confidence: 99%

“…Thus they are inadequate for an IBS study of J0632. The X-ray orbits of Chen & Takata (2022) and Malyshev et al (2019) were constructed using an inclined disk model which employs a termination shock and its interaction with an inclined disk. This is essentially a one-zone model with a disk as the shock region is assumed to be a point source (Chen & Takata 2022), whereas the IBS model of Tokayer et al (2021, TAH21 hereafter) took into account the multi-zone emission from a cone-shape IBS region.…”

Section: Orbital Solutions For J0632mentioning

confidence: 99%

“…The X-ray orbits of Chen & Takata (2022) and Malyshev et al (2019) were constructed using an inclined disk model which employs a termination shock and its interaction with an inclined disk. This is essentially a one-zone model with a disk as the shock region is assumed to be a point source (Chen & Takata 2022), whereas the IBS model of Tokayer et al (2021, TAH21 hereafter) took into account the multi-zone emission from a cone-shape IBS region. Because the IBS, unlike the one-zone termination shock, produces Dopplerboosted emission along the shock tail (e.g., Dubus 2013;An & Romani 2017;van der Merwe et al 2020), the orbit of J0632 inferred by an IBS model (Fig.…”

Section: Orbital Solutions For J0632mentioning

confidence: 99%

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Investigation of the broadband emission of the gamma-ray binary HESS J0632+057 using an intrabinary shock model

Kim¹,

An²,

Mori³

2022

Preprint

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We investigated a wealth of X-ray and gamma-ray spectral energy distribution (SED) and multiband light curve (LC) data of the gamma-ray binary HESS J0632+057 using a phenomenological intrabinary shock (IBS) model. Our baseline model assumes that the IBS is formed by colliding winds from a putative pulsar and its Be companion, and particles accelerated in the IBS emit broadband radiation via synchrotron (SY) and inverse-Compton upscattering (ICS) processes. Adopting the latest orbital solution and system geometry (Tokayer et al. 2021), we reproduced the global X-ray and TeV LC features, two broad bumps at φ ∼ 0.3 and ∼ 0.7, with the SY and ICS model components. We found these TeV LC peaks originate from ICS emission caused by the enhanced seed photon density near periastron and superior conjunction or Doppler-beamed emission of bulk-accelerated particles in the IBS at inferior conjunction. While our IBS model successfully explained most of the observed SED and LC data, we found that phase-resolved SED data in the TeV band require an additional component associated with ICS emission from pre-shock particles (produced by the pulsar wind). This finding indicates a possibility of delineating the IBS emission components and determining the bulk Lorentz factors of the pulsar wind at certain orbital phases.

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New insight into the orbital parameters of the gamma-ray binary HESS J0632 + 057

Matchett,

van Soelen

2024

Monthly Notices of the Royal Astronomical Society

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The gamma-ray binary HESS J0632+057 consists of a Be star and an undetected compact object in a ∼317 day orbit. The interpretation of the emission from this system is complicated by the lack of a clear orbital solution, as two different and incompatible orbital solutions were obtained by previous radial velocity studies of this source. In order to address this, we report on 24 new observations, covering ∼60percnt of the orbit which we have undertaken with the Southern African Large Telescope (SALT). We obtained new radial velocity measurements from cross-correlation of the narrower spectral features, and by fitting Voigt profiles to the wings of the Balmer emission lines. Additionally, we find an indication of orbital variability in the equivalent widths and V/R of the Balmer lines. Using the combined data from this study, as well as archival data from the earlier radial velocity studies, we have derived updated orbital solutions. Using reported H α emission radial velocities - previously not considered for the orbital solution - along with the new SALT data, a solution is obtained where the brighter peak in the X-ray and gamma-ray light curves is closer to periastron. However, continuing sparse coverage in the data around the expected phases of periastron indicates that the orbital solution could be improved with further observation.

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Modelling the correlated keV/TeV light curves of Be/gamma-ray binaries

Cited by 7 publications

References 128 publications

Optical spectroscopy of the Be/black hole binary MWC 656 ‐ interaction of a black hole with a circumstellar disc

Optical spectroscopy of the Be/black hole binary MWC 656 ‐ interaction of a black hole with a circumstellar disc

Investigation of the broadband emission of the gamma-ray binary HESS J0632+057 using an intrabinary shock model

New insight into the orbital parameters of the gamma-ray binary HESS J0632 + 057

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