Line feature around 73 keV from the Crab Nebula

Manchanda, R. K.; Bazzano, A.; Padula, C. La; Polcaro, V. F.; Ubertini, P.

doi:10.1086/159543

Cited by 24 publications

(6 citation statements)

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“…Our upper limits between 50 and 550 keV apply even at energies besides those at which previous detections have been reported. Our results and the comparison with earlier work, presented in Table 7, also include two cases which w ere not obviously pulsed Manchanda et al 1982;Gilfanov et al 1994. Except for the relatively low ux level reported by Massaro et al 1991 we are in apparent disagreement with these detections.…”

Section: Linescontrasting

confidence: 47%

“…For example, Mahoney, Ling, & Jacobson 1984 found that the spectrum of the pulsed emission in the region between the two peaks has the same spectral shape in the 0.05 to 10 MeV range as do the pulse peaks, while others e.g., Knight 1982 andHasinger et al 1984 suggest that the spectrum of the interpulse region is di erent. Numerous studies report the detection of lines or spectral features from the Crab nebula and pulsar Leventhal, MacCallum, & Watts 1977;Ling et al 1979;Strickman, Johnson, & Kurfess 1979;Ayre et al 1983;Agrinier et al 1990;Massaro et al 1991Massaro et al , 1992Manchanda et al 1982;Gilfanov et al 1994. In contrast, many other observations have failed to detect these lines Mahoney et al 1984;Ling et al 1977;Schwartz et al 1980;Hameury et al 1983;Knight 1982;Hasinger et al 1982. There have also been reports that the ratio of counts in the two pulse peaks, at energies 50 MeV, varies with time Clear et al 1987;Nolan et al 1993;Kanbach 1990. Previous tests for time variability in the 100 keV range, based on comparisons of light curves, have spanned time scales of less than 10 years Toor & Seward 1977;Mahoney et al 1984;Hasinger et al 1984.…”

Section: Introductionmentioning

confidence: 99%

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OSSE observations of the Crab pulsar

Ulmer

Lomatch²,

Matz³

et al. 1994

ApJ

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We present preliminary results of the Compton Gamma Ray Observatory OSSE observations of the Crab pulsar. The pulsar energy spectra and light curves are in general agreement with previous observations, validating the OSSE pulsar data acquisition modes and data analysis algorithms. The data suggest that the spectrum of the pulsar varies throughout the light curve. The interpulse" region has a slightly atter spectrum in the 600250 keV region and a slightly steeper spectrum at higher energies than the two main pulses. We nd no evidence for any lines in the spectra with a typical sensitivity of about 10 ,4 photons cm ,2 s ,1 .

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Section: Linescontrasting

confidence: 47%

Section: Introductionmentioning

confidence: 99%

OSSE observations of the Crab pulsar

Ulmer

Lomatch²,

Matz³

et al. 1994

ApJ

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“…Manchester 1981). This range of neutron star surface field strengths has been corroborated by the direct observation of cyclotron lines in Her X-1 (Trumper et al 1978), 4U 0115 + 63 (Wheaton et al 1979), GXl + 4 (Maurer et al 1982), 4U 1626 -67 (Pravdo et al 1979) and the Crab Pulsar (Manchanda et al 1982). Analyses of period changes in pulsating X-ray sources ( e.g.…”

Section: Introductionmentioning

confidence: 80%

Thermal origin of neutron star magnetic fields

Blandford

Applegate

Hernquist

1983

Monthly Notices of the Royal Astronomical Society

215

123

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It is proposed that magnetic field arises naturally in neutron stars as a consequence of thermal effects occurring in their outer crusts. The heat flux through the crust, which is carried mainly by degenerate electrons, can give rise to a possible thermoelectric instability in the solid crust which causes horizontal magnetic field components to grow exponentially with time. However, in order for the thermally driven growth to exceed ohmic decay, either the electron collision time must exceed existing estimates by a factor ~ 3 or the surface layers comprise helium. A second instability is possible if the liquid phase that lies above the solid crust also contains a horizontal magnetic field. The heat flux will drive circulation which should amplify the field strength provided that there is a seed field in excess of ~ 10 8 G.If either of these two instabilities develops the field will quickly grow to a strength of ~ 10 12 G, where the instabilities become non-linear. Further growth will saturate when either the magnetic stress exceeds the lattice yield stress or the temperature perturbations become non-linear, both of which occur at a subsurface field strength of ~ 10 14 G; the corresponding surface field strength is ~ 10 12 G. Further evolution of the magnetic field should lead to long-range order and yield neutron star magnetic dipole moments ~ 10 30 G cm3, comparable with those observed.Newly-formed neutron stars should be able to develop their dipole moments in a hundred thousand years and maintain them for as long as heat flows through the crust. Thereafter, the dipole moment should decay in several million years, as observed in the case of most radio pulsars. Neutron stars that are formed spinning rapidly, like that in the Crab Nebula, should b~ able to grow magnetic fields far more rapidly since their rotational energy can also be tapped to drive thermoelectric currents. The interiors of neutron stars in binary systems may be heated by the energy released by accreting matter. The resulting heat flux may cause the production of magnetic fields in these objects. Binary pulsars, with their unusually low and persistent fields, have probably passed through this phase.

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“…The Crab spectrum of the total emission (nebula and pulsar) in the 30 keV to 2 MeV range has been measured over the last three decades by a series of balloon (Kurfess 1971;Laros, Matteson, & Pelling 1973;Walraven et al 1975;Gruber & Ling 1977;Leventhal, MacCallum, & Watts 1977;Ling et al 1977Ling et al , 1979Strickman, Johnson, Kurfess et al 1979;Manchanda et al 1982;Graser & Schoenfelder 1982;Pelling et al 1987;McConnell et al 1987;Ubertini et al 1994) and satellite experiments (Ariel 5: Carpenter, Coe, & Engel 1976;OSO 8: Dolan et al 1977;HEAO 1: Knight 1982;Jung 1989;HEAO 3: Mahoney, Ling, & Jacobson 1984; Compton Gamma Ray Observatory [CGRO]: Ulmer et al 1995;Much et al 1996;van der Meulen et al 1998;Kuiper et al 2001). Below 300 keV, the spectrum was initially thought to be a single power law on the basis of earlier measurements by Walraven et al (1975), Carpenter et al (1976), Dolan et al (1977), and Ling et al (1979), with an index of $2.1.…”

Section: Introductionmentioning

confidence: 99%

Gamma‐Ray Spectra and Variability of the Crab Nebula Emission Observed by BATSE

Ling¹,

Wheaton²

2003

ApJ

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We report $600 days of BATSE earth occultation observations of the total gamma-ray (30 keV to 1.7 MeV) emission from the Crab Nebula between 1991 May 24 (TJD 8400) and 1994 October 3 (TJD 9628). Light curves from 35-100, 100-200, 200-300, 300-400, 400-700, and 700-1000 keV show that positive fluxes were detected by BATSE in each of these six energy bands at significances of approximately 31, 20, 9.2, 4.5, 2.6, and 1.3 , respectively, per day. We also observed significant flux and spectral variations in the 35-300 keV energy region, with timescales of days to weeks. The spectra below 300 keV, averaged over typical Compton Gamma Ray Observatory viewing periods of 6-13 days, can be well described by a broken power law with average indices of $2.1 and $2.4, varying around a spectral break at $100 keV. Above 300 keV, the long-term averaged spectra, averaged over three 400 day periods (TJD 8400-8800, 8800-9200, and 9200-9628, respectively), are well represented by the same power law with index of $2.34 up to $670 keV, plus a hard spectral component extending from $670 keV to $1.7 MeV, with a spectral index of $1.75. The latter component could be related to a complex structure observed by COMPTEL in the 0.7-3 MeV range. Above 3 MeV, the extrapolation of the power-law continuum determined by the low-energy BATSE spectrum is consistent with fluxes measured by COMPTEL in the 3-25 MeV range and by EGRET from 30-50 MeV. We interpret these results as synchrotron emission produced by the interaction of particles ejected from the pulsar with the field in different dynamical regions of the nebula system, as observed recently by the Hubble Space Telescope, XMM-Newton, and Chandra.

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Line feature around 73 keV from the Crab Nebula

Cited by 24 publications

References 0 publications

OSSE observations of the Crab pulsar

OSSE observations of the Crab pulsar

Thermal origin of neutron star magnetic fields

Gamma‐Ray Spectra and Variability of the Crab Nebula Emission Observed by BATSE

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