Discovery of a Periodic Pulsating Binary X-Ray Source in Hercules from UHURU

Tananbaum, H.; Gursky, H.; Kellogg, E.; Levinson, R.; Schreier, E.; Giacconi, R.

doi:10.1086/180968

Cited by 400 publications

(240 citation statements)

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“…In the scenario we have focused on here, the low energy emission (48% of the phase averaged total flux in the 1-100 keV energy band) is modeled as a thermal Comptonization of 0.51 keV seed photons (Titarchuk 1994), while the high energy continuum (51% of the total flux) is modeled using the BW formalism (Becker & Wolff 2007). We also add a Gaussian emission line which gives a minor contribution to the total flux (∼1%).…”

Section: Comparison To the Standard Spectral Phenomenological Modelmentioning

confidence: 99%

Study of the accreting pulsar 4U 0115+63 using a bulk and thermal Comptonization model

Ferrigno

Becker

Segreto

et al. 2009

A&A

121

148

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Context. Highly magnetized pulsars accreting matter in a binary system are bright sources in the X-ray band (0.1-100 keV). Despite the early comprehension of the basic emission mechanism, their spectral energy distribution is generally described by phenomenological or simplified models. Aims. We propose a study of the spectral emission from the high mass X-ray binary pulsar 4U 0115+63 by means of thermal and bulk Comptonization models based on the physical properties of such objects. Methods.For this purpose, we analyze the BeppoSAX data in the energy range 0.7-100 keV of the 1999 giant outburst, 12 days after the maximum. We focus first on the phase averaged emission, and then on the phase resolved spectra, by modeling the system using a two-component continuum. Results. At higher energy, above ∼7 keV, the emission is due to thermal and bulk Comptonization of the seed photons produced by cyclotron cooling of the accretion column, and at lower energy, the emission is due to thermal Comptonization of a blackbody source in a diffuse halo close to the stellar surface. Phase resolved analysis establishes that most of the emission in the main peak comes from the column, while the low energy component gives a nearly constant contribution throughout the phase. Conclusions. From the best fit parameters, we argue that the cyclotron emission is produced ∼1.7 km above the stellar surface, and escapes from the column near its base, where the absorption features are generated by the interaction with the magnetic field in the halo. We find that in 4U 0115+63, the observed spectrum is dominated by reprocessed cyclotron radiation, whereas in other bright sources with stronger magnetic fields such as Her X-1, the spectrum is dominated by reprocessed bremsstrahlung.

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Section: Comparison To the Standard Spectral Phenomenological Modelmentioning

confidence: 99%

Study of the accreting pulsar 4U 0115+63 using a bulk and thermal Comptonization model

Ferrigno

Becker

Segreto

et al. 2009

A&A

121

148

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“…The X-ray pulsar spins with a 1.24 s period and moves in a 1.7 day almost circular orbit around its companion HZ Her (Tananbaum et al 1972). Both effects cause a modulation of the observed flux in optical as well as in the X-rays.…”

Section: Introductionmentioning

confidence: 99%

Probing the outer edge of an accretion disk: a Her X-1 turn-on observed withRXTE

Kuster

Wilms

Staubert

et al. 2005

A&A

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We present the analysis of Rossi X-ray Timing Explorer (RXTE) observations of the turn-on phase of a 35 day cycle of the X-ray binary Her X-1. During the early phases of the turn-on, the energy spectrum is composed of X-rays scattered into the line of sight plus heavily absorbed X-rays. The energy spectra in the 3-17 keV range can be described by a partial covering model, where one of the components is influenced by photoelectric absorption and Thomson scattering in cold material plus an iron emission line at 6.5 keV. In this paper we show the evolution of spectral parameters as well as the evolution of the pulse profile during the turn-on. We describe this evolution using Monte Carlo simulations which self-consistently describe the evolution of the X-ray pulse profile and of the energy spectrum.

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“…If, however, we assume / close (within -10°) to 90°, the duration of X-ray eclipse suggests a radius -0.4 and #-0.5. Using the absolute values of orbital parameters given by Tananbaum et al (1972), we find the cool star could be an early A-type star of 2R Q and 2 A/©, making the X-ray source -1 M Q . From this, we expect a velocity amplitude of the visible star of -85 km s -1 , but calculations of line profiles account ing for the very large heating effect show that this would appear as an observed ampli tude of only -50 km s" 1 .…”

Section: R E Wilsonmentioning

confidence: 99%

“…IP address: 52.183.12.225, on 11 Apr 2019 at 06:11:48, subject to the Cambridge Core terms of use, behaviour); (ii) a 1-7 day cycle showing a complete, sharp X-ray eclipse lasting -0.2 of the period. Several groups of workers have derived optical light curves which indicate a continuous light variation, covering nearly 2 mag., which shows a large U-B change, and have a minimum coincident with the middle of the X-ray eclipse, (iii) a pulsation in the X-rays of period -1?24, which shows (Tananbaum et al, 1972) a time-of-arrival periodicity (1?7) which leads to values for the orbital radius (-4x 10 6 km) and velocity (-170 km s" 1 ) of the X-ray source. Very faint (<0T002) pulses have been claimed by a group at Berkeley (Davidsen et al, 1972).…”

Section: R E Wilsonmentioning

confidence: 99%

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Third Discussion Session

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Discovery of a Periodic Pulsating Binary X-Ray Source in Hercules from UHURU

Cited by 400 publications

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Study of the accreting pulsar 4U 0115+63 using a bulk and thermal Comptonization model

Study of the accreting pulsar 4U 0115+63 using a bulk and thermal Comptonization model

Probing the outer edge of an accretion disk: a Her X-1 turn-on observed withRXTE

Third Discussion Session

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