Examinando por Autor "Ducci, L."

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Acceso Abierto
Advances in Understanding High-Mass X-ray Binaries with INTEGRALand Future Directions
(Elsevier BV, 2019-12-13) Kretschmar, P.; Fürst, F.; Sidoli, L.; Bozzo, E.; Alfonso Garzón, J.; Bodaghee, A.; Chaty, S.; Chernyakova, M.; Ferrigno, C.; Manousakis, A.; Negueruela, I.; Postnov, K.; Paizis, A.; Reig, P.; Rodes Roca, J. J.; Coe, M. J.; Domingo, A.; Doroshenko, V.; Ducci, L.; Falanga, M.; Grebenev, S. A.; Grinberg, V.; Hemphill, P.; Kreykenbohm, I.; Fritz, S. K.; Li, J.; Lutovinov, A. A.; Martínez Nuñez, S.; Mas Hesse, J. M.; Masetti, N.; McBride, V. A.; Neronov, A.; Pottschmidt, K.; Rodríguez, J.; Romano, P.; Rothschild, R. E.; Santangelo, A.; Sguera, V.; Staubert, R.; Tomsick, J. A.; Torrejón, José Miguel; Torres, D. F.; Walter, R.; Wilms, J.; Wilson Hodge, C. A.; Zhang, S.; Agenzia Spaziale Italiana (ASI); Istituto Nazionale Astrofisica (INAF); Russian Foundation for Basic Research (RFBR); Agencia Estatal de Investigación (AEI); Wilms, J. [0000-0003-2065-5410]; Santangelo, A. [0000-0003-4187-9560]; Grinberg, V. [0000-0003-2538-0188]; Sguera, V. [0000-0001-8202-9381]; Martínez Núñez, S. [0000-0002-5134-4191]; Rodes Roca, J. J. [0000-0003-4363-8138]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
High mass X-ray binaries are among the brightest X-ray sources in the Milky Way, as well as in nearby Galaxies. Thanks to their highly variable emissions and complex phenomenology, they have attracted the interest of the high energy astrophysical community since the dawn of X-ray Astronomy. In more recent years, they have challenged our comprehension of physical processes in many more energy bands, ranging from the infrared to very high energies. In this review, we provide a broad but concise summary of the physical processes dominating the emission from high mass X-ray binaries across virtually the whole electromagnetic spectrum. These comprise the interaction of stellar winds with the high gravitational and magnetic fields of compact objects, the behaviour of matter under extreme magnetic and gravity conditions, and the perturbation of the massive star evolutionary processes by presence in a binary system. We highlight the role of the INTEGRAL mission in the discovery of many of the most interesting objects in the high mass X-ray binary class and its contribution in reviving the interest for these sources over the past two decades. We show how the INTEGRAL discoveries have not only contributed to significantly increase the number of high mass X-ray binaries known, thus advancing our understanding of the population as a whole, but also have opened new windows of investigation that stimulated the multi-wavelength approach nowadays common in most astrophysical research fields. We conclude the review by providing an overview of future facilities being planned from the X-ray to the very high energy domain that will hopefully help us in finding an answer to the many questions left open after more than 18 years of INTEGRAL scientific observations.
Acceso Abierto
An X-ray activity cycle on the young solar-like star ɛ Eridani
(EDP Sciences, 2020-04-15) Coffaro, M.; Stelzer, B.; Orlando, S.; Hall., J.; Metcalfe, T. S.; Wolter, U.; Mittag, M.; Sanz Forcada, J.; Schneider, P. C.; Ducci, L.; Deutsches Zentrum für Luft- und Raumfahrt (DLR); European Research Council (ERC); National Science Foundation (NSF); Agencia Estatal de Investigación (AEI); Metcalfe, T. S. https://orcid.org/0000-0003-4034-0416; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Chromospheric Ca II activity cycles are frequently found in late-type stars, but no systematic programs have been created to search for their coronal X-ray counterparts. The typical time scale of Ca II activity cycles ranges from years to decades. Therefore, long-lasting missions are needed to detect the coronal counterparts. The XMM-Newton satellite has so far detected X-ray cycles in five stars. A particularly intriguing question is at what age (and at what activity level) X-ray cycles set in. To this end, in 2015 we started the X-ray monitoring of the young solar-like star ɛ Eridani, previously observed on two occasions: in 2003 and in early 2015, both by XMM-Newton. With an age of 440 Myr, it is one of the youngest solar-like stars with a known chromospheric Ca II cycle. We collected the most recent Mount Wilson S-index data available for ɛ Eridani, starting from 2002, including previously unpublished data. We found that the Ca II cycle lasts 2.92 ± 0.02 yr, in agreement with past results. From the long-term XMM-Newton lightcurve, we find clear and systematic X-ray variability of our target, consistent with the chromospheric Ca II cycle. The average X-ray luminosity is 2 × 1028erg s−1, with an amplitude that is only a factor of 2 throughout the cycle. We apply a new method to describe the evolution of the coronal emission measure distribution of ɛ Eridani in terms of solar magnetic structures: active regions, cores of active regions, and flares covering the stellar surface at varying filling fractions. Combinations of these three types of magnetic structures can only describe the observed X-ray emission measure of ɛ Eridani if the solar flare emission measure distribution is restricted to events in the decay phase. The interpretation is that flares in the corona of ɛ Eridani last longer than their solar counterparts. We ascribe this to the lower metallicity of ɛ Eridani. Our analysis also revealed that the X-ray cycle of ɛ Eridani is strongly dominated by cores of active regions. The coverage fraction of cores throughout the cycle changes by the same factor as the X-ray luminosity. The maxima of the cycle are characterized by a high percentage of covering fraction of the flares, consistent with the fact that flaring events are seen in the corresponding short-term X-ray lightcurves predominately at the cycle maxima. The high X-ray emission throughout the cycle of ɛ Eridani is thus explained by the high percentage of magnetic structures on its surface.