Neutron Stars 1: Equation of State and Structure

Preface 1. Cosmic rays 2. Particle physics 3. Cascade equations 4. Hadrons and photons 5. Accelerator data 6. Muons 7. Neutrinos 8. Neutrino-induced muons 9. Propagation 10. Gamma rays and antiprotons 11. Acceleration 12. Acceleration to >100 TeV 13. Astrophysical beam dumps 14. Air showers 15. Electromagnetic cascades 16. Cosmic ray showers 17. Simulation techniques References Index.

Cosmic rays and particle physics.

The rotation of more than 700 pulsars has been monitored using the 76-m Lovell Telescope at Jodrell Bank. Here we report on a new search for glitches in the observations, revealing 128 new glitches in the rotation of 63 pulsars. Combining these new data with those already published, we present a data base containing 315 glitches in 102 pulsars. The data base was used to study the glitch activity among the pulsar population, finding that it peaks for pulsars with a characteristic age τ c ∼ 10 kyr and decreases for longer values of τ c, disappearing for objects with τ c > 20 Myr. The glitch activity is also smaller in the very young pulsars (τ c 1 kyr). The cumulative effect of glitches, a collection of instantaneous spin-up events, acts to reduce the regular long-term spin-down rate |u ν| of the star. The percentage of |u ν| reversed by glitch activity was found to vary between 0.5 and 1.6 per cent for pulsars with spin-down rates |u ν| between 10 −14 and 3.2 × 10 −11 Hz s −1 , decreasing to less than 0.01 per cent at both higher and lower spin-down rates. These ratios are interpreted in terms of the amount of superfluid involved in the generation of glitches. In this context, the activity of the youngest pulsar studied, the Crab pulsar, may be explained by quake-like activity within the crust. Pulsars with low spin-down rates seem to exhibit mostly small glitches, matching well the decrease of their crustal superfluid. Through the analysis of glitch sizes, it was found that the particular glitching behaviour of PSR J0537−6910 and the Vela pulsar may be shared by most Vela-like pulsars. These objects present most of their glitches with characteristic frequency and frequency derivative jumps, occurring at regular intervals of time. Their behaviour is different from other glitching pulsars of similar characteristic age.

A study of 315 glitches in the rotation of 102 pulsars

The Crab Nebula, henceforth the Crab, the remnant of the historical super- nova of 1054 AD, has long been of intense interest. The pulsar at the center of the Crab has a spin-down luminosity ∼10 5 times that of the Sun. The outer nebula holds several solar masses of material ejected by the explosion. Between the two lies the trapped pulsar wind, visible as synchrotron radia- tion at radio wavelengths through X-ray wavelengths. Recent observations with the Hubble Space Telescope, the Chandra X-ray Observatory, and a host of other instruments have provided a wealth of information about the ex- traordinary structure and dynamics of the Crab. Understanding those data requires thinking of the Crab not in terms of its individual components, but instead as a single interconnected physical system formed as the axisymmet- rical wind from the pulsar pushes its way outward through a larger freely expanding supernova remnant.

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The Crab Nebula: An Astrophysical Chimera

Author(s): Abeysekara, AU; Albert, A; Alfaro, R; Alvarez, C; Alvarez, JD; Arceo, R; Arteaga-Velazquez, JC; Solares, HAA; Barber, AS; Bautista-Elivar, N; Becerril, A; Belmont-Moreno, E; Benzvi, SY; Berley, D; Braun, J; Brisbois, C; Caballero-Mora, KS; Capistran, T; Carraminana, A; Casanova, S; Castillo, M; Cotti, U; Cotzomi, J; Leon, SCD; Fuente, EDL; Leon, CD; Deyoung, T; Dingus, BL; Duvernois, MA; Diaz-Velez, JC; Ellsworth, RW; Fiorino, DW; Fraija, N; Garcia-Gonzalez, JA; Gerhardt, M; Munoz, AG; Gonzalez, MM; Goodman, JA; Hampel-Arias, Z; Harding, JP; Hernandez, S; Hernandez-Almada, A; Hinton, J; Hui, CM; Huntemeyer, P; Iriarte, A; Jardin-Blicq, A; Joshi, V; Kaufmann, S; Kieda, D; Lara, A; Lauer, RJ; Lee, WH; Lennarz, D; Vargas, HL; Linnemann, JT; Longinotti, AL; Raya, GL; Luna-Garcia, R; Lopez-Coto, R; Malone, K; Marinelli, SS; Martinez, O; Martinez-Castellanos, I; Martinez-Castro, J; Martinez-Huerta, H; Matthews, JA; Miranda-Romagnoli, P; Moreno, E; Mostafa, M; Nellen, L; Newbold, M; Nisa, MU; Noriega-Papaqui, R; Pelayo, R; Pretz, J; Perez-Perez, EG; Ren, Z; Rho, CD; Riviere, C; Rosa-Gonzalez, D; Rosenberg, M; Ruiz-Velasco, E; Salazar, H; Greus, FS | Abstract: The Crab Nebula is the brightest TeV gamma-ray source in the sky and has been used for the past 25 years as a reference source in TeV astronomy, for calibration and verification of new TeV instruments. The High Altitude Water Cherenkov Observatory (HAWC), completed in early 2015, has been used to observe the Crab Nebula at high significance across nearly the full spectrum of energies to which HAWC is sensitive. HAWC is unique for its wide field of view, nearly 2 sr at any instant, and its high-energy reach, up to 100 TeV. HAWC's sensitivity improves with the gamma-ray energy. Above ∼1 TeV the sensitivity is driven by the best background rejection and angular resolution ever achieved for a wide-field ground array. We present a time-integrated analysis of the Crab using 507 live days of HAWC data from 2014 November to 2016 June. The spectrum of the Crab is fit to a function of the form φ(E)= φ0(E/E0)-α-β In(E/E0). The data is well fitted with values of α = 2.63 ±0.03, β = 0.15 ±0.03, and log10(φ0cm2s TeV)=-12.60±0.02 when E 0 is fixed at 7 TeV and the fit applies between 1 and 37 TeV. Study of the systematic errors in this HAWC measurement is discussed and estimated to be ±50% in the photon flux between 1 and 37 TeV. Confirmation of the Crab flux serves to establish the HAWC instrument's sensitivity for surveys of the sky. The HAWC all-sky survey will be the deepest survey of the northern sky ever conducted in the multi-TeV band.

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Observation of the Crab Nebula with the HAWC Gamma-Ray Observatory

BECAUSE of the conjecture that pulsars are neutron stars, which are possibly produced in supernova events, the possible association of pulsars with supernova remnants is of great interest. Staelin and Reifenstein recently reported1 the discovery of two pulsed radio sources near the Crab nebula, which is the remnant of the supernova observed by the Chinese in AD 1054. Pulses from both sources were described as very sporadic, and no periodic phenomena were evident.

Crab Nebula Pulsar NP 0532

How to search for weak pulsars in the radio noise picked up by telescopes. Two kinds of analysis are described; both have been used successfully at Arecibo.

Digital Search Methods for Pulsars

A SECOND pulsar in the constellation Vulpecula has been discovered through observations at the Arecibo Ionospheric Observatory. The new pulsar was discovered on August 26, 1968, almost immediately after a new digital reduction program was applied to 111.5 MHz pulsar search data taken some time earlier at this observatory. The new program has the advantage of being extremely sensitive to pulsed signals and of reducing pulsar search data very rapidly. About 4 per cent of the data available at present have now been reduced in this manner with this new pulsar giving the strongest detection. The reduced data also contain several other pulsar suspects which have yet to be checked by further observations. The new reduction program makes feasible a systematic search for pulsars at the Arecibo Ionospheric Observatory, and a paper describing the techniques used in the digital reductions is in preparation (R. V. E. Lovelace, J. M. Sutton, E. E. Salpeter and H. D. Craft, jun.).

J. M. Sutton

Papers

Crab Nebula Pulsar NP 0532

Digital Search Methods for Pulsars

New pulsar in vulpecula.