Hard X-ray tails and cyclotron features in X-ray pulsars

We review the physical processes occurring in the magnetosphere of accreting X-ray pulsars, with emphasis on those processes that give rise to observable effects in their high (E>10 keV) energy spectra. In the second part we compare the empirical spectral laws used to fit the observed spectra with theoretical models, at the light of the BeppoSAX results on the broad-band characterization of the X-ray pulsar continuum, and the discovery of new (multiple) cyclotron resonance features.Comment: Review talk given at the "X-ray Astronomy '99" Conferenc

Analisi carpologiche per la Vasca dello Specchio (Ferrara, XIV-XV sec. d.C.): metodologie d’indagine e risultati

Lo scavo condotto tra Corso Porta Reno e Via Vaspergolo, nel centro storico di Ferrara, ha portato alla luce un vano sotterraneo rettangolare denominato “Vasca dello Specchio”, utilizzato per lo smaltimento dei rifiuti tra XIV e XV secolo. Il riempimento, in parte già analizzato e pubblicato, è stato oggetto di nuove analisi carpologiche. I semi e i frutti, conservati prevalentemente per sommersione e in ottimo stato, sono complessivamente oltre 400.000 e la lista floristica comprende 168 taxa. La maggior parte dei reperti appartiene a piante coltivate/coltivabili o spontanee correlate all’uomo, che forniscono nuove informazioni sulla dieta vegetale e sull’ambiente urbano della Ferrara basso-medievale/rinascimentale. I reperti evidenziano anche pratiche domestiche e culinarie talora curiose

The broad band spectral properties of galactic X-ray binary pulsars

BeppoSAX observed several galactic binary X-ray pulsars during the Science Verification Phase and in the first year of the regular program. The complex emission spectra of these sources are an ideal target for the BeppoSAX instrumentation, that can measure the emission spectra in an unprecedented broad energy band. Using this capability of BeppoSAX a detailed observational work can be done on the galactic X-ray pulsars. In particular the 0.1-200 keV energy band allows the shape of the continuum emission to be tightly constrained. A better determination of the underlying continuum allows an easier detection of features superimposed onto it, both at low energy (Fe K and L, Ne lines) and at high energies (cyclotron features). We report on the spectral properties of a sample of X-ray pulsars observed with BeppoSAX comparing the obtained results. Some ideas of common properties are also discussed and compared with our present understanding of the emission mechanisms and processes.Comment: 6 pages, 2 figures. Uses espcrc2.sty (included).To appear in Proceedings of "The Active X-ray Sky: Results from BeppoSAX and Rossi-XTE