The “<i>K</i>‐Correction” for Irradiated Emission Lines in LMXBs: Evidence for a Massive Neutron Star in X1822−371 (V691 CrA)

Muñoz-Darias, T.; Casares, J.; Martínez‐País, I. G.

doi:10.1086/497420

Cited by 105 publications

(132 citation statements)

References 30 publications

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“…We can further constrain the mass function by applying the so-called K-correction (Muñoz-Darias et al 2005) and using the fact that K 1 = 16.32 km s −1 (Chakrabarty & Morgan 1998). The largest K-correction possible is when we assume that there is no accretion disc and almost all radiation is produced in the L 1 point.…”

Section: Discussionmentioning

confidence: 99%

Phase-resolved spectroscopy of the accreting millisecond X-ray pulsar SAX J1808.4-3658 during the 2008 outburst

Cornelisse¹,

D’Avanzo

Muñoz‐Darias³

et al. 2009

A&A

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Aims. We obtained phase-resolved spectroscopy of the accreting millisecond X-ray pulsar SAX J1808.4-3658 during its outburst in 2008 to find a signature of the donor star, constrain its radial velocity semi-amplitude (K 2 ), and derive estimates for the pulsar mass. Methods. Using Doppler images of the Bowen region, we find a significant (≥8σ) compact spot at a position where the donor star is expected. If this is a signature of the donor star, we measure K em = 248 ± 20 km s −1 (1σ confidence), which represents a strict lower limit to K 2 . Also, the Doppler map of He II λ4686 shows the characteristic signature of the accretion disc, and there is a hint of enhanced emission that may be a result of tidal distortions in the accretion disc that are expected in very low mass-ratio interacting binaries.Results. The lower limit on K 2 leads to a lower limit on the mass function of f (M 1 ) ≥ 0.10 M . Applying the maximum K-correction gives 228 < K 2 < 322 km s −1 and a mass ratio of 0.051 < q < 0.072. Conclusions. Despite the limited S /N of the data, we were able to detect a signature of the donor star in SAX J1808.4−3658, although future observations during a new outburst are still needed to confirm this. If the derived K em is correct, the largest uncertainty in determining of the mass of the neutron star in SAX J1808.4-3658 using dynamical studies lies with the poorly known inclination.

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Section: Discussionmentioning

confidence: 99%

Phase-resolved spectroscopy of the accreting millisecond X-ray pulsar SAX J1808.4-3658 during the 2008 outburst

Cornelisse¹,

D’Avanzo

Muñoz‐Darias³

et al. 2009

A&A

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“…Correcting from K N III to the true amplitude K 2 of secondary star's radial curve requires a model for the distribution of the N III λ4640 emission across the face of the secondary star. Muñoz-Darias et al (2005 have developed such a model and used it to deduce 1.52 M ⊙ < m N S < 1.85 M ⊙ . In their model the N III λ4640 line is emitted uniformly over the face of the irradiated secondary except where shadowed by a simple thin disk with a raised, optically-thick rim.…”

Section: The Masses and Dimensions Of 4u1822-371mentioning

confidence: 99%

The Structure of the Accretion Disk in the Accretion Disk Corona X-Ray Binary 4u 1822–371 at Optical and Ultraviolet Wavelengths

Bayless¹,

Robinson²,

Hynes³

et al. 2009

ApJ

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The eclipsing low-mass X-ray binary 4U 1822-371 is the prototypical accretion disk corona (ADC) system. We have obtained new time-resolved UV spectroscopy of 4U 1822-371 with the Advanced Camera for Surveys/Solar Blind Channel on the Hubble Space Telescope and new V -and J-band photometry with the 1.3-m SMARTS telescope at Cerro Tololo Inter-American Observatory. We use the new data to construct its UV/optical spectral energy distribution and its orbital light curve in the UV, V , and J bands. We derive an improved ephemeris for the optical eclipses and confirm that the orbital period is changing rapidly, indicating extremely high rates of mass flow in the system; and we show that the accretion disk in the system has a strong wind with projected velocities -2 -up to 4000 km s −1 . We show that the disk has a vertically-extended, opticallythick component at optical wavelengths. This component extends almost to the edge of the disk and has a height equal to ∼0.5 of the disk radius. As it has a low brightness temperature, we identify it as the optically-thick base of a disk wind, not as the optical counterpart of the ADC. Like previous models of 4U 1822-371, ours needs a tall obscuring wall near the edge of the accretion disk, but we interpret the wall as a layer of cooler material at the base of the disk wind, not as a tall, luminous disk rim.

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“…There are other indications in favor of the existence of massive neutron stars: 1.8M ⊙ for Vela X-1 [2] and 2M ⊙ for 4U 1822-371 [3]. In particular, this new limits on maximal mass of neutron star excluded many EOS, including hyperons and/or quarks EOS.…”

Section: Introductionmentioning

confidence: 96%

Maximal neutron star mass and the resolution of the hyperon puzzle in modified gravity

2014

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The so-called "hyperonization puzzle" in the theory of neutron stars is considered in the framework of modified f (R) gravity. We show that for simple hyperon equations of state, it is possible to obtain the maximal neutron star mass which satisfies the recent observational data for PSR J1614-2230, in higher-derivative models with power-law terms as f (R) = R+γR 2 +βR 3 . The soft hyperon equation of state under consideration is usually treated as non-realistic in the standard General Relativity. The numerical analysis of Mass-Radius relation for massive neutron stars with hyperon equation of state in modified gravity turns out to be consistent with observations. Thus, we show that the same modified gravity can solve at once three problems: consistent description of the maximal mass of neutron star, realistic Mass-Radius relation and account for hyperons in equation of state.

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The “K‐Correction” for Irradiated Emission Lines in LMXBs: Evidence for a Massive Neutron Star in X1822−371 (V691 CrA)

Cited by 105 publications

References 30 publications

Phase-resolved spectroscopy of the accreting millisecond X-ray pulsar SAX J1808.4-3658 during the 2008 outburst

Phase-resolved spectroscopy of the accreting millisecond X-ray pulsar SAX J1808.4-3658 during the 2008 outburst

The Structure of the Accretion Disk in the Accretion Disk Corona X-Ray Binary 4u 1822–371 at Optical and Ultraviolet Wavelengths

Maximal neutron star mass and the resolution of the hyperon puzzle in modified gravity

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