On the mass of the neutron star in Cyg X-2

Casares, J.; Hernández, J. I. González; Israelian, G.; Rebolo, R.

doi:10.1111/j.1365-2966.2009.15828.x

Cited by 56 publications

(44 citation statements)

References 34 publications

(52 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For a distance of 8−11 kpc (Cowley et al 1979;Smale 1998) it is thought that there is an evolved companion of 0.4−0.7 M . Recent highresolution optical spectroscopy of Casares et al (2010) provides a refined orbital solution with a period of 9.84450 ± 0.00019 d. Assuming an inclination of 62.5 ± 0.4 • from ellipsoidal fits to UBV lightcurves (Orosz & Kuulkers 1999), Casares et al found a neutron star mass of 1.71 ± 0.21 M , supporting a previous result (Casares et al 1998), while Elebert et al (2009) derived 1.5 ± 0.3 M .…”

Section: Introductionsupporting

confidence: 56%

“…We have derived the orbital phase range of the present observations using the ephemeris of Casares et al (2010) with an orbital period of 9.84450 days to be 0.324 ± 0.007−0.425 ± 0.007. This phase range is well outside the expected phase position of 0.75 where the disk bulge intercepts the line-of-sight between the X-ray emitting regions and the observer.…”

Section: A102 Page 10 Of 12mentioning

confidence: 99%

See 1 more Smart Citation

Dipping in CygnusX-2 in a multi-wavelength campaign due to absorption of extended ADC emission

Bałucińska‐Church

Schulz

Wilms³

et al. 2011

A&A

View full text Add to dashboard Cite

We report results of one-day simultaneous multiwavelength observations of Cygnus X-2 using XMM, Chandra, the European VLBI Network and the XMM Optical Monitor. During the observations, the source did not exhibit Z-track movement, but remained in the vicinity of the soft apex. It was in a radio quiescent/quiet state of <150 μJy. Strong dip events were seen as 25% reductions in X-ray intensity. The use of broadband CCD spectra in combination with narrow-band grating spectra has now demonstrated for the first time that these dipping events in Cygnus X-2 are caused by absorption in cool material in quite a unique way. In the band 0.2−10 keV, dipping appears to be due to progressive covering of the Comptonized emission of an extended accretion disk corona, the covering factor rising to 40% in deep dipping with an associated column density of 3 × 10 23 atom cm −2 . Remarkably, the blackbody emission of the neutron star is not affected by these dips, in strong contrast with observations of typical low mass X-ray binary dipping sources. The Chandra and XMM gratings directly measure the optical depths in absorption edges such as Ne K, Fe L, and O K and a comparison of the optical depths in the edges of non-dip and dip data reveals no increase of optical depth during dipping even though the continuum emission sharply decreases. Based on these findings, at orbital phase 0.35, we propose that dipping in this observation is caused by absorption in the outer disk by structures located opposite to the impact bulge of the accretion stream. With an inclination angle >60 • these structures can still cover large parts of the extended ADC, without absorbing emission from the central neutral star.

show abstract

Section: Introductionsupporting

confidence: 56%

Section: A102 Page 10 Of 12mentioning

confidence: 99%

Dipping in CygnusX-2 in a multi-wavelength campaign due to absorption of extended ADC emission

Bałucińska‐Church

Schulz

Wilms³

et al. 2011

A&A

View full text Add to dashboard Cite

show abstract

“…Casares et al (2010)). The best match is obtained when the F7 IV is broadened broadened by 98±8 km s −1 and the G0 V template to 82±16 km s…”

Section: The Orbital Variabilitymentioning

confidence: 99%

Unveiling the redback nature of the low-mass X-ray binary XSS J1227.0−4859 through optical observations★

Martino

Casares

Mason

et al. 2014

Monthly Notices of the Royal Astronomical Society

Self Cite

View full text Add to dashboard Cite

The peculiar low mass X-ray binary XSS J12270-4859, associated with the Fermi/LAT source 2FGL J1227.7-4853, was in a X-ray, gamma-ray and optical low-luminosity persistent state for about a decade until the end of 2012, when it has entered into the dimmest state ever observed. The nature of the compact object has been controversial until the detection of a 1.69ms radio pulsar early 2014. We present optical spectroscopy and optical/near-IR photometry during the previous brighter and in the recent faint states. We determine the first spectroscopic orbital ephemeris and an accurate orbital period of 6.91246(5) h. We infer a mid G-type donor star and a distance d= 1.8-2.0 kpc. The donor spectral type changes from G5 V to F5 V between inferior and superior conjunction, a signature of strong irradiation effects. We infer a binary inclination 45 o i 65 o and a highly undermassive donor, M 2 ∼ 0.06 − 0.12 M ⊙ for a neutron star mass in the range 1.4-3 M ⊙ . Thus this binary joins as the seventh member the group of "redbacks". In the high state, the emission lines reveal the presence of an accretion disc. They tend to vanish at the donor star superior conjunction, where also flares are preferentially observed together with the occurrence of random dips. This behaviour could be related to the propeller mechanism of the neutron star recently proposed to be acting in this system during the high state. In the low state, the emission lines are absent at all orbital phases indicating that accretion has completely switched-off and that XSS J12270-4859 has transited from an accretion-powered to a rotation-powered phase.

show abstract

“… (1) Smale (1998), (2) Bradshaw, Fomalont & Geldzahler (1999), (3) Kuulkers et al (2010), (4) Casares et al (2010), (5) Steeghs & Casares (2002), (6) Werner et al (2006), (7) Orosz & Kuulkers (1999), (8) inclination is unknown, fixed at given value, (9) McClintock et al (1984), (10) Vrtilek et al (1991), (11) Migliari et al (2010). …”

Section: Lmxb Spectral Energy Distribution In the Optical And Nirmentioning

confidence: 99%

Period-luminosity relation for persistent low-mass X-ray binaries in the near-infrared

Revnivtsev

Zolotukhin

Meshcheryakov

2012

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We study the relations between the X‐ray luminosity, orbital period and absolute near‐infrared magnitude of persistent low‐mass X‐ray binaries (LMXBs). We show that often the optical and near‐infrared spectral energy distributions of LMXBs can be adequately described by a simple model of an accretion disc and a secondary star reprocessing X‐ray emission from a central compact object. This gives us evidence that one can make a reliable estimate of the orbital period of a persistent LMXB using an X‐ray luminosity and an absolute infrared magnitude. Using a sample of well‐known LMXBs, we have constructed a correlation of LX, Porb and MK values that can be approximated by a straight line with root‐mean‐square scatter at the level of ∼0.3 mag. Such a correlation, being to some extent analogous to the correlation found by van Paradijs & McClintock, might be helpful for future population studies, especially in the light of forthcoming surveys of the Galaxy in the X‐ray and infrared spectral domains.

show abstract

On the mass of the neutron star in Cyg X-2

Cited by 56 publications

References 34 publications

Dipping in CygnusX-2 in a multi-wavelength campaign due to absorption of extended ADC emission

Dipping in CygnusX-2 in a multi-wavelength campaign due to absorption of extended ADC emission

Unveiling the redback nature of the low-mass X-ray binary XSS J1227.0−4859 through optical observations★

Period-luminosity relation for persistent low-mass X-ray binaries in the near-infrared

Contact Info

Product

Resources

About