Spectroscopy of the Crab Pulsar

Beskin, G. M.; Neustroev, V.

doi:10.1051/0004-6361:20010781

Cited by 5 publications

(5 citation statements)

References 19 publications

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“…However, subsequent observations did not detect these features (Sollerman et al 2000). Beskin & Neustroev (2001) also reported non-detections of the particular feature, but cautionedgiven similar claims for the Geminga -that the Crab pulsar cyclotron lines could be time-dependent.…”

Section: Cyclotron Lines and Diffuse Interstellar Bandsmentioning

confidence: 89%

“…Following the first optical spectrum of the Crab pulsar by Oke (1969) it took almost 30 years before a modern CCD spectrum was published (Nasuti et al 1996). This was followed by several investigations that provided data with medium-sized (2 − 4 m) telescopes more than 15 years ago (e.g., Sollerman et al 2000;Carramiñana et al 2000;Beskin & Neustroev 2001;Romani et al 2001;Fordham et al 2002). These observations were also followed by a series of theoretical papers aiming to interpret the optical emission (e.g., Björnsson et al 2010;Massaro et al 2006;O'Connor et al 2005;Crusius-Wätzel et al 2001).…”

Section: Introductionmentioning

confidence: 99%

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The optical and NIR spectrum of the Crab pulsar with X-shooter

Sollerman

Selsing²,

Vreeswijk

et al. 2019

A&A

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Context. Pulsars are well studied all over the electromagnetic spectrum, and the Crab pulsar may be the most studied object in the sky. Nevertheless, a high-quality optical to near-infrared spectrum of the Crab or any other pulsar has not been published to date. Aims. Obtaining a properly flux-calibrated spectrum enables us to measure the spectral index of the pulsar emission, without many of the caveats from previous studies. This was the main aim of this project, but we could also detect absorption and emission features from the pulsar and nebula over an unprecedentedly wide wavelength range. Methods. A spectrum was obtained with the X-shooter spectrograph on the Very Large Telescope. Particular care was given to the flux-calibration of these data. Results. A high signal-to-noise spectrum of the Crab pulsar was obtained from 300 nm to 2400 nm. The spectral index fitted to this spectrum is flat with α ν = 0.16 ± 0.07. For the emission lines we measure a maximum velocity of 1600 km s −1 , whereas the absorption lines from the material between us and the pulsar is unresolved at the ∼50 km s −1 resolution. A number of Diffuse Interstellar Bands and a few near-IR emission lines that have previously not been reported from the Crab are highlighted.

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Section: Cyclotron Lines and Diffuse Interstellar Bandsmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

The optical and NIR spectrum of the Crab pulsar with X-shooter

Sollerman

Selsing²,

Vreeswijk

et al. 2019

A&A

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“…For characterizing the SED, we list in Table 1 results from some of the previous observations of the spectral index, α ν , of the Crab pulsar, and indicate for which wavelength ranges these Reference α ν λ-range (Å) Nasuti et al (1996) −0.10 ± 0.01 4900−7000 Carramiñana et al (2000) 0 .2 ± 0.1 5000−7500 Sollerman et al (2000) 0 .11 ± 0.04 1140−9250 Beskin & Neustroev (2001) −0.15 ± 0.15 5000−7050 Fordham et al (2002) −0.034 ± 0.009 4600−6000 Percival et al (1993) 0 .11 ± 0.13 1680−7400 Golden et al (2000) −0.07 ± 0.19 3700−5500 Sollerman (2003) 0 .31 ± 0.02 12 400−21 800 Sandberg & Sollerman (2009) 0.27 ± 0.03 3700−38 000 observations were made (compare Fordham et al 2002, their Table 6). The uppermost part are spectroscopic observations and the lower part are photometric.…”

Section: Spectral Energy Distributionmentioning

confidence: 99%

“…Some of the measurements have used timeresolved data to estimate the phase-averaged spectral index, while most observations have been time-integrated and therefore more susceptible to bad seeing. In e.g., Beskin & Neustroev (2001), the spectrum display clear residuals from nebular subtraction. Since the surrounding nebula appears redder than the pulsar at these wavelengths (e.g.…”

Section: Spectral Energy Distributionmentioning

confidence: 99%

The location of the Crab pulsar emission region: restrictions on synchrotron emission models

Björnsson

Sandberg

Sollerman

2010

A&A

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Recent observations of the Crab pulsar show no evidence of a spectral break in the infrared regime. It is argued that the observations are consistent with a power-law spectrum in the whole observable infrared-optical range. This is taken as the starting point for evaluating of how self-consistent incoherent synchrotron models fare in a comparison with observations. Inclusion of synchrotron self-absorption proves important as does the restriction on the observed size of the emission region imposed by the relativistic beaming thought to define the pulse profile. It is shown that the observations can be used to derive two independent constraints on the distance from the neutron star to the emission region; in addition to a direct lower limit, an indirect measure is obtained from an upper limit to the magnetic field strength. Both of these limits indicate that the emission region is located at a distance considerably greater than the light cylinder radius. The implications of this result are discussed, and it is emphasized that, for standard incoherent synchrotron models to fit inside the light cylinder, rather special physical conditions need to be invoked.

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“…Most of the identified NS optical counterparts are very faint (V ≥ 25) and can be detected only via broad-band photometric observations. Optical spectroscopy has been obtained only for the youngest and brightest Crab pulsar (∼1000 yr., V = 16.6) (Nasuti et al 1996, Sollerman et al 2000, Beskin & Neustroev 2001, PSR B0540−69 (∼2000 yr., V = 22.4) (Hill et al 1997, Serafimovich et al 2004) and the third optically brightest Vela pulsar (∼10000 yr., V = 23.6) (Mignani et al 2007). The spectroscopic observations of older and fainter pulsars were first obtained by Martin et al (1998).…”

Section: Introductionmentioning

confidence: 99%

PSR B0656+14: the unified outlook from the infrared to X-rays

Zharikov,

Zyuzin,

Shibanov

et al. 2021

Preprint

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We report detection of PSR B0656+14 with the Gran Telescopio Canarias in narrow optical F657, F754, F802, and F902 and near-infrared JHK s bands. The pulsar detection in the K s band extends its spectrum to 2.2 µm and confirms its flux increase towards the infrared. We also present a thorough analysis of the optical spectrum obtained by us with the VLT. For a consistency check, we revised the pulsar near-infrared and narrow-band photometry obtained with the HST. We find no narrow spectral lines in the optical spectrum. We compile available near-infrared-optical-UV and archival 0.3-20 keV X-ray data and perform a self-consistent analysis of the rotation phase-integrated spectrum of the pulsar using unified spectral models. The spectrum is best fitted by the four-component model including two blackbodies, describing the thermal emission from the neutron star surface and its hot polar cap, the broken power-law, originating from the pulsar magnetosphere, and an absorption line near ∼0.5 keV detected previously. The fit provides better constraints on the model parameters than using only a single spectral domain. The derived surface temperature is T ∞ NS = 7.9(3) × 10 5 K. The intrinsic radius (7.8-9.9 km) of the emitting region is smaller than a typical neutron star radius (13 km) and suggests a nonuniform temperature distribution over the star surface. In contrast, the derived radius of the hot polar cap is about twice as large as the 'canonical' one. The spectrum of the nonthermal emission steepens from the optical to X-rays and has a break near 0.1 keV. The X-ray data suggest the presence of another absorption line near 0.3 keV.

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Spectroscopy of the Crab Pulsar

Cited by 5 publications

References 19 publications

The optical and NIR spectrum of the Crab pulsar with X-shooter

The optical and NIR spectrum of the Crab pulsar with X-shooter

The location of the Crab pulsar emission region: restrictions on synchrotron emission models

PSR B0656+14: the unified outlook from the infrared to X-rays

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