AUTh Laboratory of Astronomy

Gravitational waves, Visiting institute (TNA)

The Laboratory of Astronomy at the Aristotle University of Thessaloniki (AUTh), a research unit of the Department of Physics, was founded in 1943, and is a leading center for astronomical research and education in Greece. It focuses on areas like general relativity, astrophysics, cosmology, radioastronomy, astrochemistry, exoplanetary atmospheres, and observational astronomy. The facility houses a refracting telescope, and the infrastructure includes several robotic telescopes at nearby locations and in Cyprus (in collaboration with the Laboratory for Astrodynamics and Theoretical Mechanics). The Laboratory plays a key role in education, offering a large number of astronomy courses in both undergraduate and MSc programs. Members of the Laboratory participate in the Virgo Collaboration, the LISA Consortium, the Einstein Telescope, the TVLBAI study, and EHT Next, and are engaged in gravitational-wave observations, the modeling of binary neutron star mergers, data analysis using deep learning methods and simulations of black holes. In addition, there is participation in the Ariel mission and access to space-based telescopes, such as JWST.

Main contact for TNA call: Nikolaos Stergioulas

 

Available expertise

The Laboratory of Astronomy at AUTh is engaged in data analysis for gravitational wave astronomy. Within the ACME project, we provide expertise on:

  • detecting gravitational waves in LIGO and Virgo data using deep learning methods,
  • applying Bayesian parameter estimation methods using hyperbolic likelihoods,
  • constructing global-fit pipelines for space-based detectors,
  • constructing numerical models of neutron stars in general relativity and alternative theories of gravity,
  • simulating and analyzing the post-merger phase of binary-neutron star mergers.

The AUTh group is experienced in providing training on ML methods for gravitational wave astronomy – they were local organizers of the 4th G2Net Traning School.

 

Available tools

AresGW: A gravitational-wave detection code using deep learning methods (1D ResNets). It has been verified against previously published results and has led to several new gravitational-wave candidates found in O3 data. Repository: https://github.com/vivinousi/gw-detection-deep-learning

ERYN:  An advanced MCMC sampler with the capability to run with parallel tempering, multiple model types, and unknown counts within each model type using Reversible Jump MCMC techniques. One of the main applications is parameter estimation for gravitational wave sources. Repository: https://github.com/mikekatz04/Eryn

GWG: A code for estimating the confusion noise signal from gravitational waves emitted by compact Galactic Binaries, as measured by LISA. Repository: https://gitlab.in2p3.fr/Nikos/gwg

RNS:  The most widely used public-domain code for computing the properties of rapidly rotating neutron stars using tabulated equations of state. Advanced versions of the code include differential rotation, multipole moments, and alternative theories of gravity. Repository of public domain version: https://github.com/cgca/rns

UNIVERSAL RELATIONS: Codes that use machine learning to construct universal relations for rotating neutron stars. Repositories:  https://github.com/gregoryPapi/UR-for-rotating-NS-using-ML- and https://github.com/gregoryPapi/Universal-description-of-the-NS-surface-using-ML

Tutorials:

  1. Deep Learning for Gravitational Wave detection
  2. AresGW code tutorials
  3. Eryn code tutorial
  4. RNS code tutorial
  5. Surrogate models for Gravitational Wave Astronomy
  6. Bayesian parameter estimation for Gravitational Wave Astronomy
  7. Numerical models of neutron stars in GR and alternative theories
  8. Emission of gravitational waves in the post-merger phase of binary neutron star mergers

 

Involved scientists

Nikolaos Stergioulas is a Full Professor at AUTh. He is the Director of the Laboratory of Astronomy and the leader of the Virgo and LISA groups at AUTh. He is also a member of the Einstein Telescope Collaboration and the TVLBAI study. His expertise is in machine-learning methods for gravitational-wave astronomy, numerical simulations of neutron stars, and alternative theories of gravity. He is a fellow of the European Coalition for AI in Fundamental Physics (EuCAIF) and an elected board member of the Gravitational Physics Division of EPS.

George Pappas is an Assistant Professor at AUTh. His research focuses on modeling the properties, structure, and astrophysical phenomena around black holes and neutron stars. The aim is to use these objects and their environment as strong gravity laboratories for fundamental physics. He is a member of the Virgo Collaboration and the LISA Consortium, as well as a member of EHT Next.

Nikolaos Karnesis is a senior researcher at ATUh. His expertise is Bayesian methods for gravitational wave astronomy, as well as in the calibration and data analysis for space-borne detectors. He is a member of the LISA Consortium and the Virgo Collaboration. He is a member of the LISA Science Team and of the Astronomy and Fundamental Physics Panel of the European Space Sciences Committee (ESSC).

Alexandra Eleni Koloniari is a PhD student at ATUh. Her expertise is in machine-learning for gravitational-wave astronomy, with emphasis in detecting gravitational-wave events with deep-learning methods. She is developing new methods in the ARESGW code of AUTh and is a member of the Virgo Collaboration.

Grigorios Papigkiotis is a PhD student at ATUh. His expertise is in machine-learning for gravitational-wave astronomy, with emphasis in analyzing neutron star properties with machine-learning methods and in detecting gravitational-wave events using deep-learning. He is a member of the Virgo Collaboration.

Evdokia Koursoumpa is a student at ATUh. Her expertise is in the analysis of glitches in the data of the Virgo detector, applying machine-learning methods. She is a member of the Virgo Collaboration.