Between Ostrogothic and Carolingian Italy : survivals, revivals, ruptures

The victory of Justinian, achieved after a lacerating war, put an end to the ambitious project conceived and implemented by Theoderic after his arrival in Italy: that of a new society in which peoples divided by centuries-old cultural barriers would live together in peace and justice, without renouncing their own traditions but respecting shared principles inspired by the values of civilitas. What did this great experiment leave to Europe and Italy in the centuries to come? What were the survivals and the ruptures, what were the revivals of that world in early medieval society? How did that past continue to be recounted and how did it interact with the present, especially in the decisive moment of the Frankish conquest of Italy? This book aims to confront these questions, and it does so by exploring different themes, concerning politics and ideology, culture and literary tradition, law, epigraphy and archaeology

Ostrogoths vs. Franks: Imagining the Past in the Middle Ages

This introductory essay aims at highlighting some aspects concerning the connections between the Ostrogoths and Franks in the Middle Ages. To this end, cases from different contexts and chronologies have been examined: firstly, Giovanni Villani’s chronicle, which conveys a pola- rized image of the Gothic and Carolingian worlds; and then some testimonies from the ninth century, that use the Ostrogothic model in connection with the present in a more complex and ambivalent manner. The various interpretations of the Gothic world are linked by a tendency to emphasize historical analogies, that leads to an overall and protracted disinterest in the specific forms of Ostrogothic society and in the work that most documents it, i.e. Cassiodorus’ Variae

Teoderico e gli allori dei Magni

This paper deals with some of Cassiodorus’ letters focused on the relations between Theoderic’s kingdom and the Roman nobility of southern Gaul after the victory against the Franks; in particular, it exami-nes the letters on the appointment of Arcadius Placidus Magnus Felix to the consulship (Var. 2, 1-3), and the letter on the restitution to the spec-tabilis Magnus of the properties he had lost during the war (Var. 3, 18). The contents and rhetorical strategies of these texts strengthen the links between the Ostrogothic present and the Roman past, so that Cassiodo-rus, for the first and only time in the Variae, establishes a full identifica-tion between the Gothic kingdom and the imperium Romanum. These messages must be interpreted both in the light of the external relations of the Ostrogothic kingdom and in the light of the new ties between Italy and the Gallic prefecture

Observations of 4U 1626-67 with the Imaging X-ray Polarimetry Explorer

We present measurements of the polarization of X-rays in the 2-8 keV band from the pulsar in the ultracompact low mass X-ray binary 4U1626-67 using data from the Imaging X-ray Polarimetry Explorer (IXPE). The 7.66 s pulsations were clearly detected throughout the IXPE observations as well as in the NICER soft X-ray observations, which we use as the basis for our timing analysis and to constrain the spectral shape over 0.4-10 keV energy band. Chandra HETGS high-resolution X-ray spectra were also obtained near the times of the IXPE observations for firm spectral modeling. We find an upper limit on the pulse-averaged linear polarization of <4% (at 95% confidence). Similarly, there was no significant detection of polarized flux in pulse phase intervals when subdividing the bandpass by energy. However, spectropolarimetric modeling over the full bandpass in pulse phase intervals provide a marginal detection of polarization of the power-law spectral component at the 4.8 +/- 2.3% level (90% confidence). We discuss the implications concerning the accretion geometry onto the pulsar, favoring two-component models of the pulsed emission.Comment: 19 pages, 7 figures, 7 tables; accepted for publication in the Astrophysical Journa

X-ray polarimetry reveals the magnetic field topology on sub-parsec scales in Tycho's supernova remnant

Supernova remnants are commonly considered to produce most of the Galactic cosmic rays via diffusive shock acceleration. However, many questions about the physical conditions at shock fronts, such as the magnetic-field morphology close to the particle acceleration sites, remain open. Here we report the detection of a localized polarization signal from some synchrotron X-ray emitting regions of Tycho's supernova remnant made by the Imaging X-ray Polarimetry Explorer. The derived polarization degree of the X-ray synchrotron emission is 9+/-2% averaged over the whole remnant, and 12+/-2% at the rim, higher than the 7-8% polarization value observed in the radio band. In the west region the polarization degree is 23+/-4%. The X-ray polarization degree in Tycho is higher than for Cassiopeia A, suggesting a more ordered magnetic-field or a larger maximum turbulence scale. The measured tangential polarization direction corresponds to a radial magnetic field, and is consistent with that observed in the radio band. These results are compatible with the expectation of turbulence produced by an anisotropic cascade of a radial magnetic-field near the shock, where we derive a magnetic-field amplification factor of 3.4+/-0.3. The fact that this value is significantly smaller than those expected from acceleration models is indicative of highly anisotropic magnetic-field turbulence, or that the emitting electrons either favor regions of lower turbulence, or accumulate close to where the magnetic-field orientation is preferentially radially oriented due to hydrodynamical instabilities.Comment: 31 pages, 7 figures, 3 tables. Accepted for publication in ApJ. Revised versio

IXPE and XMM-Newton observations of the Soft Gamma Repeater SGR 1806-20

Recent observations with the Imaging X-ray Polarimetry Explorer (IXPE) of two anomalous X-ray pulsars provided evidence that X-ray emission from magnetar sources is strongly polarized. Here we report on the joint IXPE and XMM-Newton observations of the soft {\gamma}-repeater SGR 1806-20. The spectral and timing properties of SGR 1806-20 derived from XMM-Newton data are in broad agreement with previous measurements; however, we found the source at an all-time-low persistent flux level. No significant polarization was measured apart from the 4-5 keV energy range, where a probable detection with PD=31.6\pm 10.5% and PA=-17.6\pm 15 deg was obtained. The resulting polarization signal, together with the upper limits we derive at lower and higher energies 2-4 and 5-8 keV, respectively) is compatible with a picture in which thermal radiation from the condensed star surface is reprocessed by resonant Compton scattering in the magnetosphere, similar to what proposed for the bright magnetar 4U 0142+61.Comment: 11 pages, 3 figures, accepted for publication in Ap

Magnetic structures and turbulence in SN 1006 revealed with imaging X-ray polarimetry

Young supernova remnants (SNRs) strongly modify surrounding magnetic fields, which in turn play an essential role in accelerating cosmic rays (CRs). X-ray polarization measurements probe magnetic field morphology and turbulence at the immediate acceleration site. We report the X-ray polarization distribution in the northeastern shell of SN1006 from a 1 Ms observation with the Imaging X-ray Polarimetry Explorer (IXPE). We found an average polarization degree of $22.4\pm 3.5\%$ and an average polarization angle of $-45.4\pm 4.5^\circ$ (measured on the plane of the sky from north to east). The X-ray polarization angle distribution reveals that the magnetic fields immediately behind the shock in the northeastern shell of SN 1006 are nearly parallel to the shock normal or radially distributed, similar to that in the radio observations, and consistent with the quasi-parallel CR acceleration scenario. The X-ray emission is marginally more polarized than that in the radio band. The X-ray polarization degree of SN 1006 is much larger than that in Cas A and Tycho, together with the relatively tenuous and smooth ambient medium of the remnant, favoring that CR-induced instabilities set the turbulence in SN 1006 and CR acceleration is environment-dependent.Comment: 15 pages, 4 Figures, 2 Tables; accepted for publication in The Astrophysical Journa

X-ray pulsar GRO J1008−-57 as an orthogonal rotator

X-ray polarimetry is a unique way to probe geometrical configuration of highly-magnetized accreting neutron stars (X-ray pulsars). GRO J1008$-$57 is the first transient X-ray pulsar observed at two different flux levels by the Imaging X-ray Polarimetry Explorer (IXPE) during its outburst in November 2022. The polarization properties were found to be independent of the source luminosity, with the polarization degree varying between non-detection to about 15% over the pulse phase. Fitting the phase-resolved spectro-polarimetric data with the rotating vector model allowed us to estimate the pulsar inclination (130 deg, which is in good agreement with the orbital inclination), the position angle (75 deg) of the pulsar spin axis, and the magnetic obliquity (74 deg). This makes GRO J1008$-$57 the first confidently identified X-ray pulsar as a nearly orthogonal rotator. The results are discussed in the context of the neutron star atmosphere models and theories of pulsars' axis alignment.Comment: 11 pages, 7 figures, submitted to A&A. arXiv admin note: text overlap with arXiv:2209.0244