MAXI∕GSC image fitting analysis for transient X-ray sources

Morii, M.; Kawai, N.; Sugimori, K.; Suzuki, Masahiro; Negoro, H.; Sugizaki, M.; Nakajima, M.; Mihara, T.; Matsuoka, M.

doi:10.1063/1.3509322

Cited by 8 publications

(11 citation statements)

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“…Although RX J0440.9+4431 was observed by XMM-Newton at a higher flux level, all these luminosity estimates are in the range 10 34 −10 35 erg s −1 : the variation is smaller than a factor 10, hence the XMM-Newton observation also suggests that RX J0440.9+4431 is a persistent BeXRB. On the other hand, a large flux increase was previously reported in three different events (Morii et al 2010;Krivonos et al 2010b;Tsygankov et al 2011); based on the measured CRs, we estimated that in all cases the source luminosity had risen by up to a few 10 36 erg s −1 . This implies a source variability of at least two order of magnitudes, in contrast to the classification of RX J0440.9+4431 as a persistent source.…”

Section: Discussionsupporting

confidence: 60%

“…However, this source has since experienced three consecutive flux increases, separated by about five months from each other: the first one was detected by MAXI/GSC on 31 March 2010 (Morii et al 2010) and by RossiXTE on 6 April 2010 (Finger & Camero-Arranz 2010); the second one was observed by INTEGRAL on 1 September 2010 (Krivonos et al 2010b); the third one was seen by Swift on 29 January 2011 (Tsygankov et al 2011). The mean time between the starts of these outbursts was ∼155 days, and the peak luminosities of these flares were lower than 10 37 erg s −1 (assuming a source distance of 3.3 kpc).…”

Section: Introductionmentioning

confidence: 99%

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XMM-Newtonobservation of the persistent Be/NS X-ray binary pulsar RX J0440.9+4431

Palombara

Sidoli

Esposito

et al. 2012

A&A

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Many X-ray accreting pulsars have a soft excess below 10 keV. This feature was also detected in faint sources and at low luminosity levels, suggesting that it is an ubiquitous phenomenon. For the high luminosity pulsars (L X > 10 36 erg s −1 ), the fit to this component with thermal emission models usually provides low temperatures (kT < 0.5 keV) and large emission regions (R ≥ a few hundred km), hence it is referred to as a "soft" excess. Nevertheless, we previously found that in persistent, low-luminosity (L X ∼ 10 34 erg s −1 ) and long-period (P > 100 s) Be accreting pulsars the observed excess can be modeled with a rather hot (kT BB > 1 keV) black-body component of small area (R BB < 0.5 km), which can be interpreted as emission from the NS polar caps. In this paper, we present an analysis of an XMM-Newton observation of the Galactic Be pulsar RX J0440.9+4431, which is a poorly studied member of this class of sources. We find a best-fit period of P = 204.96 ± 0.02 s, which implies an average pulsar spin-down over the past 13 years oḟ P 6 × 10 −9 s s −1 . The estimated source luminosity is L X ∼ 8 × 10 34 erg s −1 , which is higher by a factor of less than ten compared to those obtained in the first source observations, but almost two orders of magnitude lower than those measured during the few outbursts that have been detected most recently. The source spectrum can be described with a power-law and black-body model, with kT BB = 1.34 ± 0.04 keV and R BB = 273 ± 16 m, suggesting a polar-cap origin of this component. Our results support the classification of RX J0440.9+4431 as a persistent Be/NS pulsar, and confirm that the hot black-body spectral component is a common property of this class of sources.

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Section: Discussionsupporting

confidence: 60%

Section: Introductionmentioning

confidence: 99%

XMM-Newtonobservation of the persistent Be/NS X-ray binary pulsar RX J0440.9+4431

Palombara

Sidoli

Esposito

et al. 2012

A&A

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“…The first estimate of the source orbital period was reported by Reig (2011) at ∼150 d using the orbit-tospin period relation for Be/X-ray binaries. This period would be compatible with the recurrence time of the source outbursts (150-160 d Morii et al 2010;Krivonos et al 2010a;Tsygankov et al 2012).…”

Section: Introductionmentioning

confidence: 54%

“…The first observed outburst from RX J0440.9+4431, which we are aware of, was detected on 2010 March 26, and lasted until April 15 (Morii et al 2010;Finger & Camero-Arranz 2010). The Swift/BAT light curve ( Fig.…”

Section: Introductionmentioning

confidence: 89%

RX J0440.9 + 4431: a persistent Be/X-ray binary in outburst

Ferrigno

Farinelli

Bozzo

et al. 2013

A&A

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The persistent Be/X-ray binary RX J0440.9+4431 flared in 2010 and 2011 and has been followed by various X-ray facilities (Swift, RXTE, XMM-Newton, and INTEGRAL). We studied the source timing and spectral properties as a function of its X-ray luminosity to investigate the transition from normal to flaring activity and the dynamical properties of the system. We have determined the orbital period from the long-term Swift/BAT light curve, but our determinations of the spin-period are not precise enough to constrain any orbital solution. The source spectrum can always be described by a bulk-motion Comptonization model of black body seed photons attenuated by a moderate photoelectric absorption. At the highest luminosity, we measured a curvature of the spectrum, which we attribute to a significant contribution of the radiation pressure in the accretion process. This allows us to estimate that the transition from a bulk-motion-dominated flow to a radiatively dominated one happens at a luminosity of ∼2 × 10 36 erg s −1 . The luminosity dependency of the size of the black body emission region is found to be r BB ∝ L 0.39±0.02 X . This suggests that either matter accreting onto the neutron star hosted in RX J0440.9+4431 penetrates through closed magnetic field lines at the border of the compact object magnetosphere or that the structure of the neutron star magnetic field is more complicated than a simple dipole close to the surface.

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“…Monitor of All-sky X-ray Image (MAXI) is a 520-kg all-sky X-ray monitor, which were launched on Space Shuttle Endeavour at 7:03am JST on 16 July 2009, and installed on the International Space Station (ISS) at 00:24am JST on July 27 (see figure 1), and successfully activated on August 3. During the commissioning phase from August 2009 through March 2010, we evaluate the MAXI data to understand the instrument characteristics in orbit, the flight operations, and data processing.…”

Section: Introductionmentioning

confidence: 99%