How many times have we heard the question “are we alone in the Universe” ? Does life exist somewhere else ? Does intelligent life exist ? There’s no need to introduce the topic, as countless discussions have been made through the centuries . Still this question remains one of the most (if not the most) fascinating ones about the Universe and astronomers have spent some efforts in the past decades trying to at least narrow down the possibilities. Continue reading →
Turbulence is a common chaotic phenomenon that everyone has certainly experienced: you witness the development of turbulence when you stir a coffee too vigorously or watch the smoke of a cigarette or feel the aeroplane going up and down. What makes turbulence often spectacular is the presence of several vortices which are indeed seen in many atmospheric phenomena from the magnificent tornadoes and hurricanes to the tiny dust devils. Such vortices have a certain life-time that is set by the amount of energy that sustains them and that works against viscosity, which tries to re-establish the calm and quietness of the flow.
I am mostly an observer working in the field of high energy astrophysics, doing experiments and performing observations with space and ground based telescopes. However, once in a while I also like very much to use numerical codes to solve complex physical problems that require large computational resources. So I would like to share the numerical codes that I’ve used throughout my career and that I found exceptionally useful and easy to use.
We know that black holes exist in Nature with at least two different sizes: super-massive black holes, that live in the centre of galaxies and stellar-mass black holes. The origin and evolution of these two types of black holes are very different. The millions of stellar mass black holes that populate our galaxy are mostly formed during the gravitational collapse of a massive star. The formation of super-massive black holes is much less well understood. Continue reading →
Neutron stars are few kilometres sized objects that come to life when a massive star dies in a devastating supernova explosion. A few months ago a very peculiar neutron star has been discovered in an even more peculiar location of our Galaxy. A magnetar is neutron star surrounded by a magnetic field so intense that it is billion of times stronger than the strongest magnetic field ever produced in a physics lab on Earth. Place yourself in such a strong magnetic field and you won’t survive a whole second.One such magnetar has been discovered in the Galactic Center, very close to the supermassive black hole that exists there. Continue reading →
Scientific discoveries can be divided, very broadly speaking, into four categories: major serendipitous discoveries, major discoveries that happen within a well known theoretical framework, major discoveries achieved by following unconventional ideas and minor incremental discoveries that most commonly are made when following an established agenda. The latter kind of discoveries certainly embrace the largest number of scientific papers published every day. Obviously, they should not be considered unimportant works as they constitute the building blocks that allow new ideas to sprout and grow. Serendipitous discoveries instead are perhaps what makes science a funny and challenging intellectual activity; quoting Heraclitus: “If you do not expect the unexpected, you will not find it; for it is hard to be sought out, and difficult”.
Astronomy is a very fast evolving science and astronomers have always been at the forefront when using the latest web technologies. We astronomers use the SAO/NASA Astrophysics Data System (ADS), a great bibliographic database that contains an enormous amount of papers published in astronomy, astrophysics and physics in the last century or so. We also use the Astronomer’s Telegram, a free online service used for rapid communication of astronomical news (e.g., the explosion of a new supernova) which have completely replaced the outdated IAU circulars (which were also quite expensive). Another fantastic web service is arXiv a wonderful open access pre-print service where we post our papers before or right after they are published on peer-reviewed journals.