Part I. Astronomical Background: 1. High energy astrophysics - an introduction 2. The stars and stellar evolution 3. The galaxies 4. Clusters of galaxies Part II. Physical Processes: 5. Ionisation losses 6. Radiation of accelerated charged particles and bremsstrahlung of electrons 7. The dynamics of charged particles in magnetic fields 8. Synchrotron radiation 9. Interactions of high energy photons 10. Nuclear interactions 11. Aspects of plasma physics and magnetohydrodynamics Part III. High Energy Astrophysics in our Galaxy: 12. Interstellar gas and magnetic fields 13. Dead stars 14. Accretion power in astrophysics 15. Cosmic rays 16. The origin of cosmic rays in our galaxy 17. The acceleration of high energy particles Part IV. Extragalactic High Energy Astrophysics: 18. Active galaxies 19. Black holes in the nuclei of galaxies 20. The vicinity of the black hole 21. Extragalactic radio sources 22. Compact extragalactic sources and superluminal motions 23. Cosmological aspects of high energy astrophysics Appendix References Index.

High Energy Astrophysics

The observational methods for detecting and measuring extragalactic magnetic fields are discussed, along with some new indirect methods which could be used for inferring field strengths at large redshifts which are otherwise beyond the reach of direct measurement. Various cosmological seed field generation mechanisms are reviewed, which could generate seed fields for the subsequently formed galaxies. The question of whether the original seed fields were produced in galaxies, or the pre-recombination early Universe must await a clearer picture of how the first stars and galaxies formed.

https://iopscience.iop.org/article/10.1088/0034-4885/57/4/001/pdf

Extragalactic magnetic fields

The properties of the host galaxies of a well-defined sample of 2215 radio-loud active galactic nuclei (AGN) with redshifts 0.03 10 23 W Hz -1 is a strong function of stellar mass, rising from nearly zero below a stellar mass of 10 10 M○. to more than 30 per cent at stellar masses of 5 x 10 11 M○.. In contrast to the integrated [O III] luminosity density from emission-line AGN, which is mainly produced by black holes with masses below 10 8 M○., the integrated radio luminosity density comes from the most massive black holes in the Universe. The integral radio luminosity function is derived in six ranges of stellar and black hole masses. Its shape is very similar in all of these ranges and can be well fitted by a broken power law. Its normalization varies strongly with mass, as M* 2.5 or M1.6 BH; this scaling only begins to break down when the predicted radio-loud fraction exceeds 20-30 per cent. There is no correlation between radio and emission-line luminosities for the radio-loud AGN in the sample and the probability that a galaxy of given mass is radio loud is independent of whether it is optically classified as an AGN. The host galaxies of the radio-loud AGN have properties similar to those of ordinary galaxies of the same mass, with a tendency for radio-loud AGN to be found in larger galaxies and in richer environments. The host galaxies of radio-loud AGN with emission lines match those of their radio-quiet counterparts. All of these findings support the conclusion that the optical AGN and low radio-luminosity AGN phenomena are independent and are triggered by different physical mechanisms. Intriguingly, the dependence on black hole mass of the radio-loud AGN fraction mirrors that of the rate at which gas cools from the hot atmospheres of elliptical galaxies. It is speculated that gas cooling provides a natural explanation for the origin of the radio-loud AGN activity, and it is argued that AGN heating could plausibly balance the cooling of the gas over time.

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The host galaxies of radio-loud active galactic nuclei: mass dependences, gas cooling and active galactic nuclei feedback

ABSTRA C T We have used narrow emission-line data from the new 7C Redshift Survey to investigate correlations between the narrow-line luminosities and the radio properties of radio galaxies and steep-spectrum quasars. The 7C Redshift Survey is a low-frequency (151 MHz) selected sample with a flux density limit about 25 times fainter than the 3CRR sample. By combining these samples, we can for the first time distinguish whether the correlations present are controlled by 151-MHz radio luminosity L151 or redshift z. We find unequivocal evidence that the dominant effect is a strong positive correlation between narrow-line luminosity LNLR and L151, of the form LNLR/ L 0:79^0:04 151 . Correlations of LNLR with redshift or radio properties, such as linear size or 151-MHz (rest frame) spectral index, are either much weaker or absent. We use simple assumptions to estimate the total bulk kinetic power Q of the jets in FR II radio sources, and confirm the underlying proportionality between jet power and narrow-line luminosity first discussed by Rawlings & Saunders. We make the assumption that the main energy input to the narrow-line region is photoionization by the quasar accretion disc, and relate Q to the disc luminosity, Qphot. We find that 0:05 & Q=Q phot & 1; so that the jet power is within about an order of magnitude of the accretion disc luminosity. Values of Q=Qphot , 1 require the volume filling factor h of the synchrotron-emitting material to be of the order of unity, and in addition require one or more of the following: (i) an important contribution to the energy budget from protons; (ii) a large reservoir of mildly relativistic electrons; and (iii) a substantial departure from the minimumenergy condition in the lobe material. The most powerful radio sources are accreting at rates close to the Eddington limit of supermassive black holes OMBH * 10 9 M(U, whilst lower power sources are accreting at sub-Eddington rates.

The emission line—radio correlation for radio sources using the 7C Redshift Survey

The future of cm and m-wave astronomy lies with the Square Kilometre Array (SKA), a telescope under development by a consortium of 17 countries. The SKA will be 50 times more sensitive than any existing radio facility. A majority of the key science for the SKA will be addressed through large-area imaging of the Universe at frequencies from 300 MHz to a few GHz. The Australian SKA Pathfinder (ASKAP) is aimed squarely in this frequency range, and achieves instantaneous wide-area imaging through the development and deployment of phase-array feed systems on parabolic reflectors. This large field-of-view makes ASKAP an unprecedented synoptic telescope poised to achieve substantial advances in SKA key science. The central core of ASKAP will be located at the Murchison Radio Observatory in inland Western Australia, one of the most radio-quiet locations on the Earth and one of the sites selected by the international community as a potential location for the SKA. Following an introductory description of ASKAP, this document contains 7 chapters describing specific science programmes for ASKAP. In summary, the goals of these programmes are as follows: The combination of location, technological innovation and scientific program will ensure that ASKAP will be a world-leading radio astronomy facility, closely aligned with the scientific and technical direction of the SKA. A brief summary chapter emphasizes the point, and considers discovery space.

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Science with ASKAP: The Australian square-kilometre-array pathfinder

/pdf/simultaneous-observations-of-pulsar-intensity-variations-at-1ue1cjyp92.pdf

O. B. Slee

Papers

Simultaneous observations of pulsar intensity variations at Parkes and Ootacamund.