The Chandra LETGS high resolution X-ray spectrum of the isolated neutron star RX J1856.5-3754

Burwitz, V.; Zavlin, V. E.; Neuhäuser, R.; Predehl, P.; Trümper, J.; Brinkman, A. C.

doi:10.1051/0004-6361:20011304

Cited by 100 publications

(137 citation statements)

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“…In this model, the X-ray flux comes from thermal emission from much smaller (and presumably polar cap) hot spots (Burwitz et al 2001;Pons et al 2002). For the 60 pc distance to RX J1856, Pons et al (2002) find acceptable two-…”

Section: Discussionmentioning

confidence: 92%

“…Searches for these pulsations were carried out by Burwitz et al (2001) Burwitz et al (2001) found no pulsations and placed an upper limit on the pulsed fraction (for frequencies Շ40 Hz) of ∼8%. Similar searches have been undertaken with archival ROSAT and ASCA data by Pons et al (2002), who placed a 50% confidence limit on the pulsed fraction of ∼6%.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, the inferred area of the Xray-emitting region is strongly dependent on the presence and properties of any atmospheric component. Since there are as yet no atmospheric models consistent with the current data (Burwitz et al 2001), clearly, detailed spectral analysis and modeling of the 2001 epoch Chandra data should be of great use in trying to explain the lack of pulsations from and the overall nature of this enigmatic object. …”

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confidence: 96%

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A Deep Search for Pulsations from the Nearby Isolated Neutron Star RX J1856.5−3754

Ransom

Gaensler

Slane

2002

The Astrophysical Journal

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We present the results of a deep search for pulsations from the nearby isolated neutron star RX J1856.5Ϫ3754 using the 450 ks director's discretionary time Chandra observation completed on 2001 October 15. No pulsations were detected. We find a 99% confidence upper limit on the pulsed fraction of ∼4.5% for worst-case sinusoidal pulsations with frequency Շ50 Hz and frequency derivatives Ϫ Hz s Ϫ1 . The nondetection Ϫ10 Ϫ15

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Section: Discussionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 96%

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A Deep Search for Pulsations from the Nearby Isolated Neutron Star RX J1856.5−3754

Ransom

Gaensler

Slane

2002

The Astrophysical Journal

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“…The ROSAT PSPC spectra with low energy resolution were consistent with Planckian energy distributions with blackbody temperatures kT in the range 40 -100 eV and little attenuation by interstellar absorption. More recent high resolution observations of the two brightest objects RX J1856.4-3754 (Burwitz et al 2001) and RX J0720.4-3125 (Paerels et al 2001;Pavlov et al 2002;Kaplan et al 2003b) were performed using the low energy transmission grating (LETG) aboard Chandra and the reflection grating spectrometers (RGS) of XMMNewton. In particular the high signal to noise LETG spectrum from a 500 ks Chandra observation of RX J1856.4-3754 did not reveal any significant deviation from a blackbody spectrum (Burwitz et al 2001(Burwitz et al , 2003.…”

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confidence: 99%

“…More recent high resolution observations of the two brightest objects RX J1856.4-3754 (Burwitz et al 2001) and RX J0720.4-3125 (Paerels et al 2001;Pavlov et al 2002;Kaplan et al 2003b) were performed using the low energy transmission grating (LETG) aboard Chandra and the reflection grating spectrometers (RGS) of XMMNewton. In particular the high signal to noise LETG spectrum from a 500 ks Chandra observation of RX J1856.4-3754 did not reveal any significant deviation from a blackbody spectrum (Burwitz et al 2001(Burwitz et al , 2003. The statistical quality and energy band coverage of the RGS and LETG spectra of RX J0720.4-3125 are however insufficient to detect subtle narrow features in the spectrum (Paerels et al 2001).…”

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confidence: 99%

The magnificent seven: magnetic fields and surface temperature distributions

Haberl

2007

Isolated Neutron Stars: From the Surface to the Interior

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Presently seven nearby radio-quiet isolated neutron stars discovered in ROSAT data and characterized by thermal X-ray spectra are known. They exhibit very similar properties and despite intensive searches their number remained constant since 2001 which led to their name "The Magnificent Seven". Five of the stars exhibit pulsations in their X-ray flux with periods in the range of 3.4 s to 11.4 s. XMM-Newton observations revealed broad absorption lines in the X-ray spectra which are interpreted as cyclotron resonance absorption lines by protons or heavy ions and / or atomic transitions shifted to X-ray energies by strong magnetic fields of the order of 10 13 G. New XMM-Newton observations indicate more complex X-ray spectra with multiple absorption lines. Pulse-phase spectroscopy of the best studied pulsars RX J0720.4-3125 and RBS 1223 reveals variations in derived emission temperature and absorption line depth with pulse phase. Moreover, RX J0720.4-3125 shows long-term spectral changes which are interpreted as due to free precession of the neutron star. Modeling of the pulse profiles of RX J0720.4-3125 and RBS 1223 provides information about the surface temperature distribution of the neutron stars indicating hot polar caps which have different temperatures, different sizes and are probably not located in antipodal positions.

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A solar super‐flare as cause for the ¹⁴C variation in AD 774/5?

Neuhäuser

Hambaryan

2014

Astron Nachr

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We present further considerations regarding the strong 14C variation in AD 774/5. For its cause, either a solar super‐flare or a short gamma‐ray burst were suggested. We show that all kinds of stellar or neutron star flares would be too weak for the observed energy input at Earth in AD 774/5. Even though Maehara et al. (2012) present two super‐flares with ∼1035 erg of presumably solar‐type stars, we would like to caution: These two stars are poorly studied and may well be close binaries, and/or having a M‐type dwarf companion, and/or may be much younger and/or much more magnetic than the Sun – in any such case, they might not be true solar analog stars. From the frequency of large stellar flares averaged over all stellar activity phases (maybe obtained only during grand activity maxima), one can derive (a limit of) the probability for a large solar flare at a random time of normal activity: We find the probability for one flare within 3000 years to be possibly as low as 0.3 to 0.008 considering the full 1σ error range. Given the energy estimate in Miyake et al. (2012) for the AD 774/5 event, it would need to be ∼2000 stronger than the Carrington event as solar super‐flare. If the AD 774/5 event as solar flare would be beamed (to an angle of only ∼24°), 100 times lower energy would be needed. A new AD 774/5 energy estimate by Usoskin et al. (2013) with a different carbon cycle model, yielding 4 ot 6 time lower 14C production, predicts 4–6 times less energy. If both reductions are applied, the AD 774/5 event would need to be only ∼4 times stronger than the Carrington event in 1859 (if both had similar spectra). However, neither 14C nor 10Be peaks were found around AD 1859. Hence, the AD 774/5 event (as solar flare) either was not beamed that strongly, and/or it would have been much more than 4‐6 times stronger than Carrington, and/or the lower energy estimate (Usoskin et al. 2013) is not correct, and/or such solar flares cannot form (enough) 14C and 10Be. The 1956 solar energetic particle event was followed by a small decrease in directly observed cosmic rays. We conclude that large solar super‐flares remain very unlikely as the cause for the 14C increase in AD 774/5. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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The Chandra LETGS high resolution X-ray spectrum of the isolated neutron star RX J1856.5-3754

Cited by 100 publications

References 20 publications

A Deep Search for Pulsations from the Nearby Isolated Neutron Star RX J1856.5−3754

A Deep Search for Pulsations from the Nearby Isolated Neutron Star RX J1856.5−3754

The magnificent seven: magnetic fields and surface temperature distributions

A solar super‐flare as cause for the ¹⁴C variation in AD 774/5?

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The Chandra LETGS high resolution X-ray spectrum of the isolated neutron star RX J1856.5-3754

Cited by 100 publications

References 20 publications

A Deep Search for Pulsations from the Nearby Isolated Neutron Star RX J1856.5−3754

A Deep Search for Pulsations from the Nearby Isolated Neutron Star RX J1856.5−3754

The magnificent seven: magnetic fields and surface temperature distributions

A solar super‐flare as cause for the 14C variation in AD 774/5?

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A solar super‐flare as cause for the ¹⁴C variation in AD 774/5?