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Bridging Local and Global Universe via gravitational astrometry: The Milky Way paradigm

Bridging Local and Global Universe via gravitational astrometry: The Milky Way paradigm 20 MarzoMar 2025 14:30 - 23:55 UTC

SPEAKER: Mariateresa Crosta
Senior Researcher INAF-OATo, Osservatorio Astrofisico di Torino
 
TITLEBridging Local and Global Universe via gravitational astrometry: The Milky Way paradigm
 
ABSTRACTThe ancient branch of Astronomy dedicated to the measurement of the star positions and their movements in the Universe, fundamental even for the measurement of human time, is nowadays dominated by Einstein's theory. Highly accurate astrometric measurements in space, inaugurated by the ESA Gaia satellite a decade ago, force fundamental astronomy to move from the classical paradigm, responding to Newton's gravity, to that of Einstein's General Relativity, the current standard theory of gravity.   The crucial point is to reconstruct the astronomical measurements starting from a relativistic observer inevitably embedded in the local gravitational fields and to define the observables consistently with the theory of measurement in GR, taking into account that the propagation through space-time of the photon emitted by the star contains physical information to decipher, including gravitational waves. Then, with a relativistic-compliant astrometry delivered by Gaia, the question before us is to what extent the reconstruction of our Galaxy, i.e., Gaia's main goal, is dictated by General Relativity or Newton dynamics. The answer would assure a coherent local cosmological laboratory for the predictions of the Lambda-CDM model at the Milky Way scale and it will constitutes the best template for other similar galaxies. Besides that, at the observer's scale, gravitational astrometry offers new tools to observe tiny variations in the fabric of space-time induced by interposed masses or passing gravitational waves, to infer their strength and pinpoint -with unprecedented precision- the direction to the gravitational source for a complete multi-length profile. Furthermore, the large amount of information accumulated over the 10+ years  by  Gaia can be exploited to catch possible weak gravitational signatures in the Gaia raw epoch data and, for example, further boost synergies with other GW detectors, especially with PTA .

In brief, Gravitational Astronomy in this capacity is part of Fundamental Physics and an essential tool for building up a spacetime map of our Universe. 

 
BIOMariateresa Crosta is a Senior Researcher of the National Institute of AstroPhysics (INAF) at the Astrophysical Observatory of Turin. Her main research field is the gravitational metrology applied to astrophysics, to Local Cosmology, kinematics/dynamics/structure of Galaxy, tests on General Relativity and alternative theories of gravity, relativistic effects in the inverse light ray tracing problem, gravitational waves, fundamental physics tests in space and spacetime navigation. Since 2000 she is engaged in the Gaia space astrometric mission of the European Space Agency (ESA, launched in 2013), whose main task is to construct a three-dimensional relativistic map of the Galaxy. The need of a relativistic models suitable for the analysis and interpretation of high precision astrometric data - now in full operation at Italian Data Processing Center (DPCT) - and for new gravitational tests, their validation  has been the main subject of her research activity.  In this respect she is responsible of the "Theoretical comparison between relativistic models" within the context of the Coordinate Unit 3 (CU3) of the Gaia Data Processing and Analysis Consortium (DPAC).

In 2012 she created the interdisciplinary event "The Time Machine Factory [unspeakeable, speakable]" (https://indico.ict.inaf.it/event/751/) over years focused on causality violation, non-locality, black holes, and gravitational/quantum metrology, in collaboration with INRiM, Politecnico of Turin, SIGRAV and University of Turin (Dep. of Mathematics) with the aim to push new frontiers in astronomy, astrophysics, mathematics, space technologies and quantum physics.
She is also very active in cultural astronomy and contributed to several multidisciplinary events within the context of the Gaia mission as its legacy with old astronomy,  and many aspects of modern astrophysics. 

 
DATE/TIME: Thursday 20 March 2025, at 2:30pm CET.
LOCATION: Accademia Pontaniana
 
The colloquium will also be broadcast online, on Zoom.
Meeting ID: 841 4421 2706    |    Passcode: 656302
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