Research Activities

Here is a (non ordered) list of my main research interests. Scrolling down you will also find more information on selected topics.

  • Multimessenger astrophysics, including gravitational waves and high-energy astroparticle physics;
  • Experimental methods for the detection of gravitational waves, with particular attention to future generation of gravitational wave detectors, including the third-generation Einstein Telescope project;
  • Multiwavelength investigation of high-energy astrophysical sources,  mainly pulsars and compact binary systems;
  • Development of advanced data analysis tools, including machine learning and deep learning, for physics and astronomy;
  • Study and characterization of gravitational wave detectors, with particular attention to noise hunting and mitigation in the Advanced Virgo interferometer;

Machine learning, open data and advanced computing for Physics

Science is also entering in the era of Big Data, and it is therefore extremely interesting to develop and apply new analysis techniques to the huge amount of data that we are collecting in our experiments. As a member of the Virgo collaboration, I have started working on applying machine learning advanced data analysis techniques to gravitational waves, focusing mainly on the characterization of the detector and on the detection of sources.  We published a first set of studies for a neural network pipeline that is able to detect and distinguish transient noise sources known as glitches in the gravitational wave detectors (Razzano & Cuoco, 2016). As a part of the REINFORCE project, I also coordinated the development of GWitchHunters, a project involving citizen science and gravitational waves.

I am also involved in the development of the Gravitational Wave Open Science Center (GWOSC), a joint LIGO-Virgo project to deliver open gravitational wave data to the worldwide community.

Multimessenger studies of transient high-energy sources

With the discovery of gravitational waves in 2015, we now have a new, powerful tool to study the cosmos. One of the most promising ways of studying the Universe is through the combined data from different “messengers”, i.e. photons, neutrinos, cosmic rays, and gravitational waves. In particular, I am focusing on the joint studies of sources using gravitational waves and high-energy photons, like x rays and gamma rays. Coalescences of binary systems formed by a neutron star and/or black hole are the most promising multimessenger sources, since they are believed to be connected with the bright short Gamma Ray Bursts. We can use the joint observations to constrain emission models for these source, and we can study the performance and scenarios in this direction using ad-hoc simulations, as we did recently with binary neutron star systems (Patricelli et al., 2016)

Lightcurve of Geminga obtained from Fermi-LAT (from Abdo et al. 2010)  

Multiwavelength and multimessenger emission from pulsars

Pulsars constitute the dominant population of gamma-ray sources in our Galaxy. They are natural laboratories for the study of Physics in extreme conditions of gravity and electromagnetic fields and key probes to study fundamental physics. I am working on data analysis of gamma-ray pulsars, starting from photons provided by Fermi-LAT. I have worked on some prominent pulsars like the Vela (PSR J0835-4510) and Geminga (PSR J0633+1746) pulsars, providing results of unprecendented detail, useful to provide new insights in the magnetosphere of these objects.

More recently, I also started working on the precise timing based on gamma rays only, and I am particularly interested to variability phenomena in pulsars. In this field, I contributed to the discovery of PSR J2021+4026, the first variabile gamma-ray pulsar ever found (Allafort et al., 2013).

Multiwavelength observations are also a key ingredient for understanding pulsar emission, from radio to gamma rays. Collaborating with various teams in the Fermi collaboration, I participate in themultiwavelength campaigns aimed at finding counterparts of Fermi-LAT pulsars, using the major observatories at optical and X-rays wavelenghts (Weisskopf et al. 2011, Mignani et al., 2016, Razzano et al., 2013).

Pulsars are also expected to emit gravitational waves. I am therefore also interested in studying their gravitational wave emission and its properties.

The pulsar in CTA supernova remnant, the first new pulsar discovered with blind searches (Credits: NASA/Fermi-LAT Collaboration)

Novel search techniques for gamma-ray pulsars

The large amount of gamma-ray data provided by Fermi-LAT has allowed the discovery of many new gamma-ray pulsars. Working in collaboration with other groups in the Fermi-LAT Collaboration, such as that at the University of California in Santa Cruz, I participated in the development and improvement of search algorithms, in particular for blind searches of pulsars. The sparseness of gamma-ray data makes blind searches very challenging and CPU intensive: developing new blind search techniques is therefore an exciting and challenging tasks, both from theoretical and observational point of view (See, e.g. Abdo et al. 2009b, Saz Parkinson et al. 2010, Pletsch et al. 2011).

Model describing the magnetosphere and gamma-ray emission from a pulsar. Credits: NASA

Gamma-ray Pulsar Simulations  (2004-2008)

The study of high-energy emission from pulsars was the main focus of my Ph.D project. This project mainly took place before the launch of Fermi and so was mainly based on simulations, aimed at evaluating the LAT capabilities for detecting gamma-ray pulsars at testing the official Fermi analysis tools for pulsars. To this scope, I developed PulsarSpectuma software package that can create realistic energy and time distributions of gamma rays from pulsars (Razzano et al. 2009). PulsarSpectrum accounts for all the phenomena that affect the photon arrival times from a pulsar (frequency spin-down, timing noise, Roemer, Einstein and Shapiro delays), including also pulsars in binary systems. This simulator was used for various papers, e.g. Razzano & Harding 2007, Dormody et al. 2011.

Fireball model for GRBs. Credits: NASA

GRB Simulations and LAT GRB fast trigger (2003)

This project was part of my master thesis in 2003 and was based on a simulator of Gamma Ray Bursts (GRBs) developed by N. Omodei within the LAT collaboration. Starting from a population of simulated GRBs developed before the launch of Fermi, I studied the LAT performances in detecting these sources, and developed a simple (and quite preliminary)  algorithm for providing a fast system of GRB alert and localization that relied on raw measurements in the LAT tracker and calorimeter and on a quick reconstruction of tracks.

Diagram of the Large Area Telescope (LAT). Credits: NASA/Fermi-LAT Collaboration

Construction and Development of the Fermi Large Area Telescope (2003-2008)

I started my research career in 2003 as an undergraduate in the LAT Collaboration before the launch of Fermi, participating in the hardware characterization and testing of the LAT silicon-strip tracker (Atwood et al. 2007). Its detector technology and its vastly improved performance relative to previous generations of space-based gamma-ray missions, have been crucial in the great success of the LAT. As a part of my Master thesis project, I participated in the testing and assembly of various tracker subsystems, from the silicon strip wafers to the full tracker towers. Furthermore, I studied the performance of the tracker using detailed Montecarlo simulations provided by the package Gleam.