Observando los efectos de la Relatividad General alrededor de los agujeros negros

Blog divulgativo.Observaciones astronómicas de la materia que rodea los agujeros negros ponen en evidencia algunas predicciones de la Relatividad General en condiciones de campo gravitatorio fuerte. Una de ellas, el redshift gravitatorio, no solo se observa de forma rutinaria sino que se usa para medir la rotación del agujero negro. El spin de los agujeros negros gigantes encierra la clave de su crecimiento, e indirectamente de la evolución de las galaxias.Peer Reviewe

Soft versus Hard X-ray emission in AGN: partial covering and warm plus cold absorber models

We analyse the ROSAT PSPC hardness ratio and the 0.5-2 keV to 2-10 keV flux ratio of 65 Active Galactic Nuclei (AGN) for which there are both ROSAT archival observations available and 2-10 keV fluxes, mostly from the HEAO-1 MC-LASS survey. We conclude that the simplest spectral model for the AGN that can accommodate the variety of X-ray colours obtained is a standard power law (with energy spectral index $\alpha\sim 0.9$) plus a $\sim 0.1$ keV black body both partially absorbed. In our sample, type 1 AGN require an absorbing column around $10^{22}\, {\rm cm}^{-2}$ with covering fractions between 20 and 100\%, while type 2 AGN display larger columns and $\sim 100\%$ coverage. This simple model also provides a good link between soft and hard AGN X-ray luminosity functions and source counts. We also consider a warm absorber as an alternative model to partial covering and find that the the presence of gas in two phases (ionized and neutral) is required.Comment: 10 pages, Latex (mn.sty), 1 table, 5 figures included (epsf), postscript version also available via anonymous ftp at ftp://astsun1.unican.es/pub/ceballos/ . Accepted for publication in MNRA

Las ventanas abiertas por el Hubble

Blog divulgativo.El telescopio espacial Hubble ha hecho realidad el sueño del astrónomo: observar el universo sin atmósfera. El Hubble descubrió las galaxias más lejanas y localizó átomos de hidrógeno en el universo más cercano. Y continúa acercando, a través de sus imágenes, la belleza y los misterios del cosmos a la sociedad.Peer Reviewe

I+D: por qué y para qué

Blog divulgativo.La I+D es una actividad esencial en una sociedad avanzada, cuyos beneficios permean en la ciencia, la tecnología, la metodología, la economía y la cultura.Peer Reviewe

Athena science requirements

Trabajo presentado al Athena Topical Panel Chairs Meeting, celebrado en Bolonia (Italia) del 2 al 3 de febrero de 2015.-- ESA Athena Science Study Team.Peer Reviewe

Twisted electrons as an imaging tool for probing chiral molecules in strong field ionization

Orbital angular momentum (OAM) carried by vortex beams has seen an explosion of interest across fields and this is particularly true in attosecond physics. Given that twisted electrons have been shown to be sensitive to the chirality of molecules, exploring this sensitivity on the attosecond scale is a particularly exciting prospect. The OAM of photoelectrons has been theoretically studied discussing ways to measure and understand the ionization via an analytic formalism. This opens up the possibility of using the photoelectron OAM as an imaging tool. However, in most of the earlier studies the effects of the initial state on the photoelectron OAM have been neglected. In this project, using an analytic formalism to produce chiral hydrogen states, we have investigated how the photoelectron OAM in strong field ionization can be used to image molecular chirality

Astronomia per al segle XXI

En aquest article recullo una descripció d'on és l'Astronomía actual a Espanya i a Europa en termes de producció científica, installacions i problemes. També dono prospectiva de cap on anirà l'Astronomia durant les properes dècades, tan dels problemes científics més importants que abordarà com de les infrastructures que caldran.In this paper I present a description on where today's Spanish and European Astronomy stands in terms of scientific production, resources and problems. I present a prospect on where Astronomy is heading to for the next decades, both from the point of view of science goals and on the infrastructures neede

Exploring the hot and energetic universe with ESA's Athena mission

Trabajo presentado al 3rd Joint CNRS-CSIC Workshop: "New frontiers in Astrophysics: from the laboratory to space", celebrado en Madrid (España) del 14 al 15 de septiembre de 2015.Peer Reviewe