Group will teach analysis of Fermi LAT data in dark matter school

On the final week of July, members of our research group (Fabio, Raniere & Rodrigo) will be teaching a lesson on the analysis of Fermi LAT gamma-ray observations in the School and Workshop on Dark Matter and Neutrino Detection at ICTP-SAIFR. In this hands-on activity, we will teach how to analyze gamma-ray data for a dwarf galaxy, do a simple estimate of the dark matter cross section and reproduce the analysis described in Ackermann et al. (2015).

It will be fun!

New grad student in the group obtains FAPESP scholarship

Let’s congratulate Artur Vemado─the newest graduate student in the group─who got a prestigious FAPESP scholarship. Artur just graduated with an astronomy degree at USP. His project will consist of incorporating radiative cooling in the energy equation of hot accretion flows, in order to investigate state transitions in black hole binaries.

New paper: The Multiwavelength Spectrum of NGC 3115

Last week, in collaboration with astrophysicists from USA and China, our group’s paper was accepted for publication in Monthly Notices of the Royal Astronomical Society (MNRAS). The paper is about the properties of the spectral energy density (SED) of the nearby galaxy NGC 3115, that hosts a billion solar mass black hole in a low-luminosity  active galactic nucleus (LLAGN). Behind the spectrum of this galaxy there is a lot of information about the state of the gas flow around the supermassive black hole.

This work is a compilation of observational data of NGC 3115 nucleus followed by modeling of the spectrum considering the electromagnetic processes for the case of a radiatively inefficient accretion flow (RIAF), as the observation suggests. The main part of the work is the analysis of the radio emission that can be well-explained only considering the synchrotron emission from the RIAF, without the need of relativistic jet arising from the LLAGN,

The main result of the paper is a tight constraint on the density profile (ρ) of the accretion flow ρ(r) ∝ r -0.73 +0.01-0.02 which implies an important mass-loss via subrelativistic outflows (i.e. winds) in the RIAF. Our modeling suggests a nonthermal population of electrons in the flow too, similarly to SgrA*—the supermassive black hole in the center of our Galaxy—models.

sed3115
The main plot of the paper. In the left the thermal SED. In the right is a zoom in radio region of spectrum: the red dash-dotted line is the thermal component of electron population and the blue dashed line is due to the nonthermal electron population, the black solid line is the resulting spectrum.