The optical and X-ray surface brightness of the Crab Nebula. I - A cosmic-ray diffusion model

1976 ◽  
Vol 205 ◽  
pp. 563 ◽  
Author(s):  
S. L. Weinberg ◽  
J. Silk
Keyword(s):  
Diffusion Model ◽  
Surface Brightness ◽  
Crab Nebula ◽  
Cosmic Ray ◽  
X Ray ◽  
Ray Diffusion ◽  
The Crab Nebula

scholarly journals High energy cosmic photons and neutrinos

1965 ◽  
Vol 23 ◽  
pp. 195-225
Author(s):  
R. J. Gould ◽  
G. R. Burbidge
Keyword(s):  
Supernova Remnants ◽  
Crab Nebula ◽  
Meson Production ◽  
Cosmic Ray ◽  
High Energy ◽  
Relativistic Electrons ◽  
X Ray ◽  
Hard Radiation ◽  
The Galaxy ◽  
The Crab Nebula

This review concentrates primarily on the problem of interpreting the recent X-ray and γ-ray observations of celestial sources. The expected fluxes of hard radiation from various processes are estimated (when possible) and are compared with the observations. We compute the synchrotron, bremsstrahlung, and (inverse) Compton spectra originating from relativistic electrons produced (via meson production) in the galaxy and intergalactic medium by cosmic ray nuclear collisions; the spectra from π°-decay are also computed. Neutron stars, stellar coronae, and supernova remnants are reviewed as possible X-ray sources. Special consideration is given to the processes in the Crab Nebula. Extragalactic objects as discrete sources of energetic photons are considered on the basis of energy requirements; special emphasis is given to the strong radio sources and the possibility of the emission of hard radiation during their formation. The problem of the detection of cosmic neutrinos is reviewed.As yet, no definite process can be identified with any of the observed fluxes of hard radiation, although a number of relevant conclusions can be drawn on the basis of the available preliminary observational results. In particular, some cosmogonical theories can be tested.

scholarly journals Modelling the ArH+ emission from the Crab nebula

2017 ◽  
Vol 472 (4) ◽  
pp. 4444-4455 ◽  
Author(s):  
F. D. Priestley ◽  
M. J. Barlow ◽  
S. Viti
Keyword(s):  
Surface Brightness ◽  
Crab Nebula ◽  
Dissociative Recombination ◽  
Cosmic Ray ◽  
Far Infrared ◽  
Ionization Rate ◽  
Infrared Emission ◽  
Upper Limits ◽  
Vibration Rotation ◽  
The Crab Nebula

Abstract We have performed combined photoionization and photodissociation region (PDR) modelling of a Crab nebula filament subjected to the synchrotron radiation from the central pulsar wind nebula, and to a high flux of charged particles; a greatly enhanced cosmic-ray ionization rate over the standard interstellar value, ζ0, is required to account for the lack of detected [C i] emission in published Herschel SPIRE FTS observations of the Crab nebula. The observed line surface brightness ratios of the OH+ and ArH+ transitions seen in the SPIRE FTS frequency range can only be explained with both a high cosmic-ray ionization rate and a reduced ArH+ dissociative recombination rate compared to that used by previous authors, although consistent with experimental upper limits. We find that the ArH+/OH+ line strengths and the observed H2 vibration–rotation emission can be reproduced by model filaments with nH = 2 × 104 cm−3, ζ = 107ζ0 and visual extinctions within the range found for dusty globules in the Crab nebula, although far-infrared emission from [O i] and [C ii] is higher than the observational constraints. Models with nH = 1900 cm−3 underpredict the H2 surface brightness, but agree with the ArH+ and OH+ surface brightnesses and predict [O i] and [C ii] line ratios consistent with observations. These models predict HeH+ rotational emission above detection thresholds, but consideration of the formation time-scale suggests that the abundance of this molecule in the Crab nebula should be lower than the equilibrium values obtained in our analysis.

scholarly journals The Binary X-Ray Stars – the Observational Picture

1975 ◽  
Vol 67 ◽  
pp. 411-464 ◽  
Author(s):  
Herbert Gursky ◽  
Ethan Schreier
Keyword(s):  
Neutron Star ◽  
Thermal Radiation ◽  
Crab Nebula ◽  
Cosmic Ray ◽  
Stellar Systems ◽  
X Ray ◽  
Pathological Conditions ◽  
The Galaxy ◽  
The Crab Nebula

When X-ray sources in the galaxy were discovered in 1962 (Giacconi et al., 1962) it was only possible to speculate on their nature, which centered on supernova and cosmic-ray phenomena since these were the only very energetic events known. In particular, the discovery of an X-ray source associated with the Crab Nebula led to the idea that the emission might be the thermal radiation from the surface of a hot, neutron star. However, it was soon demonstrated (Bowyer et al., 1964) that a neutron star could not be responsible for the bulk of the X-radiation from the Crab, and it was not possible to exclude highly pathological conditions in otherwise ordinary stellar systems as being responsible for the X-ray sources (cf. Hayakawa and Matsuoka, 1964).

scholarly journals New Measurement of the Vertical Atmospheric Density Profile from Occultations of the Crab Nebula with X-Ray Astronomy Satellites Suzaku and Hitomi

2020 ◽  
Author(s):  
Satoru Katsuda ◽  
Hitoshi Fujiwara ◽  
Yoshitaka Ishisaki ◽  
Yoshitomo Maeda ◽  
Koji Mori ◽  
...  
Keyword(s):  
Density Profile ◽  
Crab Nebula ◽  
Atmospheric Density ◽  
X Ray ◽  
The Crab Nebula

scholarly journals Spectral Variation of Hard X-Ray Emission from the Crab Nebula with the Suzaku Hard X-Ray Detector

2013 ◽  
Vol 65 (4) ◽  
pp. 74 ◽  
Author(s):  
Tomomi Kouzu ◽  
Makoto S. Tashiro ◽  
Yukikatsu Terada ◽  
Shin’ya Yamada ◽  
Aya Bamba ◽  
...  
Keyword(s):  
Crab Nebula ◽  
Spectral Variation ◽  
X Ray ◽  
The Crab Nebula

scholarly journals X-ray Dips in AGN and Microquasars – Collapse Timescales of Inner Accretion Disc

2020 ◽  
Author(s):  
Mayur B Shende ◽  
Prashali Chauhan ◽  
Prasad Subramanian
Keyword(s):  
Collisionless Plasma ◽  
Cosmic Ray ◽  
Outer Radius ◽  
Accretion Disc ◽  
Accretion Discs ◽  
X Rays ◽  
Temporal Behaviour ◽  
X Ray ◽  
Ray Diffusion ◽  
3C 120

Abstract The temporal behaviour of X-rays from some AGN and microquasars is thought to arise from the rapid collapse of the hot, inner parts of their accretion discs. The collapse can occur over the radial infall timescale of the inner accretion disc. However, estimates of this timescale are hindered by a lack of knowledge of the operative viscosity in the collisionless plasma comprising the inner disc. We use published simulation results for cosmic ray diffusion through turbulent magnetic fields to arrive at a viscosity prescription appropriate to hot accretion discs. We construct simplified disc models using this viscosity prescription and estimate disc collapse timescales for 3C 120, 3C 111, and GRS 1915+105. The Shakura-Sunyaev α parameter resulting from our model ranges from 0.02 to 0.08. Our inner disc collapse timescale estimates agree well with those of the observed X-ray dips. We find that the collapse timescale is most sensitive to the outer radius of the hot accretion disc.

scholarly journals The X-Ray Spectra of Cygnus XR-1 and the Crab Nebula

1968 ◽  
Vol 1 ◽  
pp. 202-205
Author(s):  
Laurence E. Peterson
Keyword(s):  
Power Law ◽  
Crab Nebula ◽  
Atmospheric Depth ◽  
Significance Level ◽  
X Ray ◽  
One Year ◽  
The Crab Nebula

In this paper we wish to present briefly the latest results which have been obtained on the hard X-ray spectra of two strong sources in the Northern skies. These observations, which have been discussed in detail previously (Peterson et al., 1967), were made from balloons launched at Palestine, Texas, to 3 gm/cm2 atmospheric depth during September 1966. The Crab Nebula and the Cygnus XR-1 were observed to have a differential number power law spectra with an index of about –2 over the 20–200 keV range. Both sources have the same intensity within about 10%. The Crab Nebula has been observed on two occasions, one year apart, and showed no change in intensity over this range at about a 5% significance level.

Sign in / Sign up

Export Citation Format

Share Document