Balloon observations of galactic high-energy X-ray sources

Maurer, G.; Johnson, W. N.; Kurfess, J. D.; Strickman, M. S.

doi:10.1086/159730

Cited by 32 publications

(10 citation statements)

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“…A good fit to the data is formally obtained by the superposition of a bremsstrahlung at 4.4 keV and a black body at 1.2 keV. We consider also the high energy observations of Maurer et al (1982), obtained during a balloon flight in May 1976, which detected the source in the 18-60 keV range, with the low energy point at a level comparable to that of the EXOSAT observations. The high energy count rate is well fitted by a power law of spectral index 2.8 ± 0.7.…”

Section: Discussionmentioning

confidence: 90%

Dynamically Comptonized Spectra from Near-critical Accretion onto Neutron Stars

Zampieri¹,

Turolla²,

Treves³

1993

ApJ

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We investigate the effects of dynamical Comptonization on the emergent radiation spectrum produced by near critical accretion onto a neutron star.The flow dynamics and the transfer of radiation are self-consistently solved in the case of a spherically symmetric, "cold", pure scattering flow, including general relativity. A sequence of models, each characterized by the value of the total observed luminosity, was obtained assuming that the spectrum at the star surface is black body in shape. It is found that when the luminosity approaches the Eddington limit dynamical effects become important shifting the spectrum to the blue and producing a power-law, high-energy tail. The relevance of these results in connection with the observed spectral properties of LMXBs, and of Cyg X-2 in particular, are discussed.

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Section: Discussionmentioning

confidence: 90%

Dynamically Comptonized Spectra from Near-critical Accretion onto Neutron Stars

Zampieri¹,

Turolla²,

Treves³

1993

ApJ

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“…This causes considerable uncertainty in the time of phase 0, but is justified by the close agreement with the time of the low energy 'dip' in the data sets where this was known. Kendziorra et al (1982), (e) Laurent et al (1993), (f) Maurer et al (1982) and (g) Mony et al (1991).…”

Section: General Features Of Gx 1+4 Pulse Profilesmentioning

confidence: 97%

Luminosity Dependent Changes of Pulse Profiles in the X-ray Binary GX 1+4

Greenhill

Storey

1998

Publ. – Astron. Soc. Aust

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Abstract:We have reviewed the X-ray pulse profiles from a large number of observations of the accreting binary pulsar GX 1+4 obtained during the last 25 years. The profiles cover various energy ranges between 1 and 100 keV. Using these data we present a coherent picture of present and past pulse profiles and the variations of these pulse profiles with time. The pulse shape is dependent on both the X-ray luminosity and whether the pulsar is spinning up or down. Profiles measured during the GX 1+4 high state in the 1970s are all trailing edge bright. Subsequently the profiles have generally been symmetric or leading edge bright. Rossi X-ray Timing Explorer (RXTE) satellite data taken in July 1996 show that similar pulse shape variations can occur on a timescale of hours. The implications of this new information for accretion models is discussed.

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“…GX 304-1; Maurer et al 1982), high energy cutoff power-law (e.g. 4U 0115+63, 4U 1145-61, GX 304-1; White et al 1983), Fermi Dirac cutoff powerlaw (e.g.…”

Section: Pulse-phase-averaged Spectroscopymentioning

confidence: 99%

Suzakuview of the Be/X-ray binary pulsar GX 304-1 during Type I X-ray outbursts

Jaisawal

Naik

Epili

2016

Mon. Not. R. Astron. Soc.

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We report the timing and spectral properties of Be/X-ray binary pulsar GX 304-1 by using two Suzaku observations during its 2010 August and 2012 January X-ray outbursts. Pulsations at ∼275 s were clearly detected in the light curves from both the observations. Pulse profiles were found to be strongly energy-dependent. During 2010 observation, prominent dips seen in soft X-ray ( 10 keV) pulse profiles were found to be absent at higher energies. However, during 2012 observation, the pulse profiles were complex due to the presence of several dips. Significant changes in the shape of the pulse profiles were detected at high energies (>35 keV). A phase shift of ∼0.3 was detected while comparing the phase of main dip in pulse profiles below and above ∼35 keV. Broad-band energy spectrum of pulsar was well described by a partially absorbed Negative and Positive power-law with Exponential cutoff (NPEX) model with 6.4 keV iron line and a cyclotron absorption feature. Energy of cyclotron absorption line was found to be ∼53 and 50 keV for 2010 and 2012 observations, respectively, indicating a marginal positive dependence on source luminosity. Based on the results obtained from phase-resolved spectroscopy, the absorption dips in the pulse profiles can be interpreted as due to the presence of additional matter at same phases. Observed positive correlation between cyclotron line energy and luminosity, and significant pulse-phase variation of cyclotron parameters are discussed in the perspective of theoretical models on cyclotron absorption line in X-ray pulsars.

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Balloon observations of galactic high-energy X-ray sources

Cited by 32 publications

References 0 publications

Dynamically Comptonized Spectra from Near-critical Accretion onto Neutron Stars

Dynamically Comptonized Spectra from Near-critical Accretion onto Neutron Stars

Luminosity Dependent Changes of Pulse Profiles in the X-ray Binary GX 1+4

Suzakuview of the Be/X-ray binary pulsar GX 304-1 during Type I X-ray outbursts

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