Broad-band spectral analysis of Aql X-1

Raichur, Harsha; Misra, Ranjeev; Dewangan, G. C.

doi:10.1111/j.1365-2966.2011.19075.x

Cited by 19 publications

(22 citation statements)

References 32 publications

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“…We can repeat this analysis to estimate the mass of MAXI J1727-203 with the NS Aql X-1. For this, we took the temperature of Aql X-1 in the soft state of its 2007 outburst (∼0.66 keV, Raichur, Misra & Dewangan 2011). Considering a mass of ∼1.4 M for the NS in Aql X-1, we obtained a mass of ∼2 M for the compact object in MAXI J1727-203.…”

Section: Nature Of the Compact Object In Maxi J1727-203mentioning

confidence: 99%

X-ray spectral and timing evolution of MAXI J1727–203 with NICER

Alabarta

Altamirano

Méndez

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We present a detailed X-ray spectral and variability study of the full 2018 outburst of MAXI J1727–203 using NICER observations. The outburst lasted approximately four months. Spectral modelling in the 0.3–10 keV band shows the presence of both a soft thermal and a hard Comptonised component. The analysis of these components shows that MAXI J1727–203 evolved through the soft, intermediate and hard spectral states during the outburst. We find that the soft (disc) component was detected throughout almost the entire outburst, with temperatures ranging from ∼0.4 keV, at the moment of maximum luminosity, to ∼0.1 keV near the end of the outburst. The power spectrum in the hard and intermediate states shows broadband noise up to 20 Hz, with no evidence of quasi-periodic oscillations. We also study the rms spectra of the broadband noise at 0.3 − 10 keV of this source. We find that the fractional rms increases with energy in most of the outburst except during the hard state, where the fractional rms remains approximately constant with energy. We also find that, below 3 keV, the fractional rms follows the same trend generally observed at energies >3 keV, a behaviour known from previous studies of black holes and neutron stars. The spectral and timing evolution of MAXI J1727–203, as parametrised by the hardness-intensity, hardness-rms, and rms-intensity diagrams, suggest that the system hosts a black hole, although we could not rule out a neutron star.

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Section: Nature Of the Compact Object In Maxi J1727-203mentioning

confidence: 99%

X-ray spectral and timing evolution of MAXI J1727–203 with NICER

Alabarta

Altamirano

Méndez

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…There are a handful of candidates that seem to be undetectable even in deep radio pulsation searches, but are by all other accounts strong redback MSP candidates. The 716 Hz MSP in Terzan 5 is actually one of these eclipsing redback binaries, so conceivably 1) The assumed fluxes are as follows: Sco X-1, 0.5-10 keV flux of 1.6 × 10 −7 erg/cm 2 /s (D'Aì et al, 2007); Aql X-1, 0.5-10 keV flux of 3.3 × 10 −9 erg/cm 2 /s (Raichur et al, 2011); XTE J1807-294, 0.5-10 keV flux of 1.7 × 10 −10 erg/cm 2 /s (Campana et al, 2003). Figure 9 Spin limits on the EOS.…”

Section: Spin Measurementmentioning

confidence: 99%

Dense matter with eXTP

Watts

Poutanen

et al. 2018

Sci. China Phys. Mech. Astron.

117

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In this White Paper we present the potential of the Enhanced X-ray Timing and Polarimetry (eXTP) mission for determining the nature of dense matter; neutron star cores host an extreme density regime which cannot be replicated in a terrestrial laboratory. The tightest statistical constraints on the dense matter equation of state will come from pulse profile modelling of accretion-powered pulsars, burst oscillation sources, and rotation-powered pulsars. Additional constraints will derive from spin measurements, burst spectra, and properties of the accretion flows in the vicinity of the neutron star. Under development by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Science, the eXTP mission is expected to be launched in the mid 2020s.

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“…In fact, Aql X-1 shows milli-second X-ray pulsations at frequencies of 550 Hz (Zhang et al 1998;Casella et al 2008), which corresponds to a Keplerian orbit of the inner disk radius at 11.5 R G , where R G = GM/c 2 . An Fe Kα line has been modeled with Gaussian components in previous observations, but then lacked both the sensitivity and resolution to analyze the line in detail (Raichur et al 2011;Güngör et al 2014;Sakurai et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Measuring a Truncated Disk in Aquila X-1

King

Tomsick²,

Miller

et al. 2016

ApJL

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We present NuSTAR and Swift observations of the neutron star Aquila X-1 during the peak of its July 2014 outburst. The spectrum is soft with strong evidence for a broad Fe Kα line. Modeled with a relativistically broadened reflection model, we find that the inner disk is truncated with an inner radius of 15 ± 3R G . The disk is likely truncated by either the boundary layer and/or a magnetic field. Associating the truncated inner disk with pressure from a magnetic field gives an upper limit of B < 5 ± 2 × 10 8 G. Although the radius is truncated far from the stellar surface, material is still reaching the neutron star surface as evidenced by the X-ray burst present in the NuSTAR observation.

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Broad-band spectral analysis of Aql X-1

Cited by 19 publications

References 32 publications

X-ray spectral and timing evolution of MAXI J1727–203 with NICER

X-ray spectral and timing evolution of MAXI J1727–203 with NICER

Dense matter with eXTP

Measuring a Truncated Disk in Aquila X-1

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