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Milan, Italy

The Istituto Nazionale di Astrofisica , or INAF for short, is the most important Italian institution conducting scientific research in astronomy and astrophysics. Researches performed by the scientific staff of the Institute go from the study of the planets and minor bodies of the solar system up to researches of cosmological interest . Wikipedia.

Maccone C.,Istituto di Astrofisica Spaziale e Fisica Cosmica
Acta Astronautica | Year: 2014

In a recent paper (Maccone, 2011 [15]) and in a recent book (Maccone, 2012 [17]), this author proposed a new mathematical model capable of merging SETI and Darwinian Evolution into a single mathematical scheme. This model is based on exponentials and lognormal probability distributions, called "b-lognormals" if they start at any positive time b ("birth") larger than zero. Indeed: Darwinian evolution theory may be regarded as a part of SETI theory in that the factor fl in the Drake equation represents the fraction of planets suitable for life on which life actually arose, as it happened on Earth.In 2008 (Maccone, 2008 [9]) this author firstly provided a statistical generalization of the Drake equation where the number N of communicating ET civilizations in the Galaxy was shown to follow the lognormal probability distribution. This fact is a consequence of the Central Limit Theorem (CLT) of Statistics, stating that the product of a number of independent random variables whose probability densities are unknown and independent of each other approached the lognormal distribution if the number of factors is increased at will, i.e. it approaches infinity.Also, in Maccone (2011 [15]), it was shown that the exponential growth of the number of species typical of Darwinian Evolution may be regarded as the geometric locus of the peaks of a one-parameter family of b-lognormal distributions constrained between the time axis and the exponential growth curve. This was a brand-new result. And one more new and far-reaching idea was to define Darwinian Evolution as a particular realization of a stochastic process called Geometric Brownian Motion (GBM) having the above exponential as its own mean value curve.The b-lognormals may be also be interpreted as the lifespan of any living being, let it be a cell, or an animal, a plant, a human, or even the historic lifetime of any civilization. In Maccone, (2012 [17, Chapters 6, 7, 8 and 11]), as well as in the present paper, we give important exact equations yielding the b-lognormal when its birth time, senility-time (descending inflexion point) and death time (where the tangent at senility intercepts the time axis) are known. These also are brand-new results. In particular, the σ=1 b-lognormals are shown to be related to the golden ratio, so famous in the arts and in architecture, and these special b-lognormals we call "golden b-lognormals".Applying this new mathematical apparatus to Human History leads to the discovery of the exponential trend of progress between Ancient Greece and the current USA Empire as the envelope of the b-lognormals of all Western Civilizations over a period of 2500 years.We then invoke Shannon's Information Theory. The entropy of the obtained b-lognormals turns out to be the index of "development level" reached by each historic civilization. As a consequence, we get a numerical estimate of the entropy difference (i.e. the difference in the evolution levels) between any two civilizations. In particular, this was the case when Spaniards first met with Aztecs in 1519, and we find the relevant entropy difference between Spaniards an Aztecs to be 3.84 bits/individual over a period of about 50 centuries of technological difference. In a similar calculation, the entropy difference between the first living organism on Earth (RNA?) and Humans turns out to equal 25.57 bits/individual over a period of 3.5 billion years of Darwinian Evolution.Finally, we extrapolate our exponentials into the future, which is of course arbitrary, but is the best Humans can do before they get in touch with any alien civilization. The results are appalling: the entropy difference between aliens 1 million years more advanced than Humans is of the order of 1000 bits/individual, while 10,000 bits/individual would be requested to any Civilization wishing to colonize the whole Galaxy (Fermi Paradox).In conclusion, we have derived a mathematical model capable of estimating how much more advanced than humans an alien civilization will be when SETI succeeds. © 2013 IAA. Source

Caraveo P.A.,Istituto di Astrofisica Spaziale e Fisica Cosmica
Annual Review of Astronomy and Astrophysics | Year: 2014

Isolated neutron stars (INSs) were the first sources identified in the field of high-energy gamma-ray astronomy. In the 1970s, only two sources had been identified, the Crab and Vela pulsars. However, although few in number, these objects were crucial in establishing the very concept of a gamma-ray source. Moreover, they opened up significant discovery space in both the theoretical and phenomenological fronts. The need to explain the copious gamma-ray emission of these pulsars led to breakthrough developments in understanding the structure and physics of neutron star (NS) magnetospheres. In parallel, the 20-year-long chase to understand the nature of Geminga unveiled the existence of a radio-quiet, gamma-ray-emitting INS, adding a new dimension to the INS family. We are living through an extraordinary time of discovery. The current generation of gamma-ray detectors has vastly increased the population of known gamma-ray-emitting NSs. The 100 mark was crossed in 2011, and we are now over 150. The gamma-ray-emitting NS population exhibits roughly equal numbers of radio-loud and radio-quiet young INSs, plus an astonishing, and unexpected, group of isolated and binary millisecond pulsars (MSPs). The number of MSPs is growing so rapidly that they are on their way to becoming the most numerous members of the family of gamma-ray-emitting NSs. Even as these findings have set the stage for a revolution in our understanding of gamma-ray-emitting NSs, long-term monitoring of the gamma-ray sky has revealed evidence of flux variability in the Crab Nebula as well as in the pulsed emission from PSR J2021+4026, challenging a four-decades-old, constant-emission paradigm. Now we know that both pulsars and their nebulae can, indeed, display variable emission. Copyright © 2014 by Annual Reviews. Source

Pallocchia G.,Istituto di Astrofisica Spaziale e Fisica Cosmica
Journal of Geophysical Research: Space Physics | Year: 2013

The interaction of an interplanetary (IP) shock with the terrestrial magnetosphere causes some noticeable effects on the global scale structure of the magnetosphere itself. One of these effects is given by an earthward motion of the bow shock followed, some minutes later, by a sunward displacement. As demonstrated by past observational studies, in agreement with the theory of the shock-shock collision, the earthward motion of the bow shock is due directly to the interplanetary shock impact on it. Differently, the origin of the sunward motion of the bow shock is still not well understood. In this regard, on the basis of some issues of the present observational study, we suggest a possible mechanism to account for the aforementioned outward displacement. Our event, observed by the Cluster SC3 spacecraft on day 7 November 2004, is related to a magnetosheath perturbation triggered by an IP shock impact. The main result of the data analysis is the first identification of a reverse (i.e., sunward directed) fast magnetosonic wave just after the IP shock passage. The identification has been performed via a direct comparison of the observations with the MHD equations of nonlinear magnetosonic waves. The reverse fast wave consists of a smooth compression, approximately 2 min long, which is most of the magnetosheath plasma density increase produced by the entire perturbation. We point out that signatures of this reverse wave are observable in two other events as well as in a three-dimensional MHD simulation reported in the literature on the topic. Moreover, we provide a possible interpretation of this reverse wave in terms of a transient pressure build-up in the magnetosheath due to the post-shock reconfiguration of the plasma flow around the magnetopause obstacle. © 2012. American Geophysical Union. All Rights Reserved. Source

Mereghetti S.,Istituto di Astrofisica Spaziale e Fisica Cosmica
Brazilian Journal of Physics | Year: 2013

The high-energy sources known as anomalous X-ray pulsars (AXPs) and soft γ-ray repeaters (SGRs) are well explained as magnetars: isolated neutron stars powered by their own magnetic energy. After explaining why it is generally believed that the traditional energy sources at work in other neutron stars (accretion, rotation, residual heat) cannot power the emission of AXPs/SGRs, I review the observational properties of the 20 AXPs/SGRs currently known and describe the main features of the magnetar model. In the last part of this review, I discuss the recent discovery of magnetars with low external dipole field and some of the relations between AXPs/SGRs and other classes of isolated neutron stars. © 2013 Sociedade Brasileira de Física. Source

Peron R.,Istituto di Astrofisica Spaziale e Fisica Cosmica
Monthly Notices of the Royal Astronomical Society | Year: 2013

We deal here with the combination of satellites' orbital residuals time series used to estimate relativistic effects and at the same time to overcome some systematics. In a recent paper by Lorenzo Iorio, it is argued about a significant contribution to the error budget of Lense-Thirring effect measurement performed by combining LAGEOS and LAGEOS II data, considering as well as a possible future measurement using also LARES data. We show here, by a proper interpretation of the combination formulas, that this contribution is indeed negligible. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. Source

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