Seventeenth Marcel Grossmann Meeting

Confirmed Plenary Speakers

	Federico   Abbate	Updates on pulsar discoveries and timing with MeerKAT Pulsar observations have been an important target for MeerKAT having two Large Survey Projects (MeerTIME and TRAPUM) dedicated to them. This has led to the discovery of more than 200 new pulsars within globular clusters, unidentified Fermi sources, the Magellanic clouds and the Galactic disk. These discoveries have pushed the boundaries of our knowledge of the pulsar properties. Furthermore, the timing of the known pulsars has led to numerous measurements of neutron star masses, further tests of General Relativity, large population studies of pulsars, important results on the properties of globular clusters and exciting results on the timing of pulsar for the search of low-frequency gravitational waves.
	Lorenzo   Amati
	Manuela   Campanelli
	Marta   Colleoni	The LVK Collaboration
	Pasham   Dheeraj	Repeating Transients fromt Centers of Galaxies as Extreme Mass Ratio Binaries
	Christopher   Fryer	Collapsar/Magnetar Progenitors and their relation to Gamma-ray Bursts and Hypernovae In the late 1998, SN 1998bw, the supernova associated with GRB 980425, catapulted the collapsar engine (caused by the collapse of a massive rotating star to  a black hole) to the top of the list of proposed engines for these cosmic explosions.  Another engine argues that the collapse of a massive star to a magnetar could also produce these GRBS.  The rarity of these events argues that only a small subset of massive stars create collapsars or magnetars with jets sufficiently strong to produce GRBs.   In general, the difficulty lies in making stars with sufficiently high angular momentum to activate the collapsar disk or magnetar engines.   The progenitor scenarios and their engines make different predictions for the properties of the GRB properties (durations, strengths, environments) and their associated hypernovae and broad-lined supernovae.    Here we review the strengths and weaknesses of both engines and progenitor scenarios, comparing their predictions to observables.  These comparisons will constrain the possible engines/progenitors and we will discuss these constraints.
	Adriano   Fontana	News from the James Webb Space Telescope
	Elena   Giorgi	Electromagnetic-gravitational perturbations of Kerr-Newman black holes Black hole solutions in General Relativity are parametrized by their mass, spin and charge. In this talk, I will motivate why the charge of black holes adds interesting dynamics to solutions of the Einstein equation thanks to the interaction between gravitational and electromagnetic radiation. Such radiations are solutions of a system of coupled wave equations with a symmetric structure which allows to define a combined energy-momentum tensor for the system. Finally, I will show how this physical-space approach is resolutive in the most general case of Kerr-Newman black hole, where the interaction between the radiations prevents the separability in modes.
	Eva   Hackmann
	Sergiu   Klainerman	The nonlinear stability of slowly  rotating Kerr black holes The full proof of the nonlinear stability of Kerr consists of  five papers, three written in collaboration with Jeremie Szeftel, one in collaboration  with Elena and Jeremie Szeftel  and another supporting paper authored  by Dawei Shen.   In my lecture I will  describe the main architecture of the proof   as well  as some of the most important  consequences.
	Kentaro   Komori	DECIGO
	Jutta   Kunz	Black holes in alternative gravity theories
	Maura Pilia	Fast Radio Bursts
	Claus   Laemmerzahl
	Vladimir   Lipunov	Extreme Universe We will talk about the emergence of new sciences such as “Gravitational-wave astronomy”, “Neutrino extragalactic astronomy”, “Transient radio astronomy”, "Fast Transient X-ray Astronomy".
	Di   Li
	Manfred   Lindner	Hunting dark matter with the XENON experiments A brief reminder of the case for particle dark matter and general search strategies will be followed by a description of the XENON dark matter program. The main part of the talk will cover details about the currently running XENONnT detector, the latest results and an outlook on future plans.
	Andrea   Possenti	The science of EPTA (European Pulsar Timing Array) A Pulsar Timing Array (PTA) exploits the remarkable rotational stability of a sample of the rapidly spinning “recycled” pulsars in order to provide the possibility to search for gravitational waves (GWs) in the ultra-long period range, between few months to few decades. Therefore, by acting as galactic-scale GW detectors, the PTAs can explore a portion of the GW spectrum which is not charted by other already operating or planned instruments. The most recent results of the efforts of the various PTA teams are very intriguing, showing the first evidence for a detection, still to be corroborated by additional results. The talk will report on the foundations, the status, and the perspectives of these experiments, with particular focus on the case of the European Pulsar Timing Array (EPTA) contributions, resulting from more than two decades of available pulsar observations, as well as parallel theoretical and analysis developments
	Luciano   Rezzolla
	Fulvio   Ricci	Status of Einstein Telescope
	Paolo   Soffitta	IXPE re-shapes astrophysics through the lens of X-ray polarimetry In the early 1960s, as X-ray Astronomy was beginning to take shape, the critical role of X-ray polarimetry became apparent. By 2001, significant progress had been made, demonstrating the effective use of the photoelectric effect in gas as a breakthrough technique in Astrophysics. It wasn't until 2021 that an observatory with the required sensitivity utilizing the photoelectric effect could be launched. The Imaging X-ray Polarimetry Explorer (IXPE), a NASA-ASI SMEX mission, became the first Small Explorer mission equipped with three telescopes. Here, I will explore the earliest efforts in this field, the enabling technologies the IXPE mission's objectives and significant findings in its first two and half years. Highlights include Supernova Remnants, insights into acceleration processes, understanding the inner structures of compact objects like Black Holes and Neutron Stars, and Active Galactic Nuclei. I will look to future opportunities from IXPE's results.
	Annapurni  Subramaniam	The Thirty Meter Telescope
	Rashid   Sunyaev
	Daniele   Vetrugno	Unleashing the scientific potential of LISA LISA is considered by a growing part of the relevant scientific community to be one of the most exciting and impacting observatories from space in the next 30 years. The scientific case it carries with it is enormous, ranging from the supermassive black holes to the Galactic binaries’ astrophysics via cosmology and fundamental physics. Not to mention its invaluable discovery potential. Added to this, is the complexity of the almost unprecedented technological challenge. To fulfill its promises, the observatory will have to measure to picometer level the distance between free-falling test masses (TMs) on a baseline of 2.5 million kilometers, by using laser interferometry. Furthermore, it must be able to maintain TMs as inertial references at the sub-femto-g level in terms of the relative acceleration between them. Those performances will depend on the design of the Optical Metrology System (OMS) and Gravity Reference System (GRS), this last one being for a large part a legacy of LISA Pathfinder (LPF), but also on a complex interaction between the LISA subsystems and the entire satellite surrounding them, and on crucial in-orbit operations, calibrations, and instrument noise characterizations, some of them only possible downstream of the Time Delay Interferometry observable calculations. In this talk, we will describe the LISA mission, its design and performances, and the critical in-orbit operations needed to achieve them. We will also give an update of the project status and what’s ahead of us in the next few years.
	Sarah   Vigeland	Searching for Nanohertz Gravitational Waves with Pulsar Timing Arrays Pulsar timing arrays are sensitive to low-frequency gravitational waves with periods of months to decades. They do so by precisely timing a collection of millisecond pulsars, whose extremely stable rotation makes them ideal for measuring perturbations in spacetime. Gravitational waves induce correlations in the pulse arrival times that follows a characteristic pattern known as the Hellings-Downs curve. Recently, pulsar timing array experiments around the world published the first evidence of nanohertz gravitational waves in the form of a gravitational wave background. In this talk, I will discuss how pulsar timing arrays detect gravitational waves, describe recent results from the NANOGrav collaboration and the International Pulsar Timing Array (IPTA) collaboration, and discuss future prospects for finding nanohertz gravitational waves from a variety of sources.
	Yue-Liang    Wu	The Taiji Chinese Project
	Karen   Yang	Fermi/eRosita Bubbles as relics of the past activity of the Galaxy's central black hole The eROSITA X-ray satellite has revealed two gigantic bubbles extending to ~80° above and below the Galactic center (GC). The morphology of these ‘eROSITA bubbles’ bears a remarkable resemblance to the Fermi bubbles previously discovered by the Fermi Gamma-ray Space Telescope and its counterpart, the microwave haze. The physical origin of these striking structures has been intensely debated; however, because of their symmetry about the GC, they probably originate from some energetic outbursts from the GC in the past. In this talk, I will review important progress made over the years in terms of understanding their physical origin, and show that the Fermi/eROSITA bubbles likely originate from past activity of the GC black hole, Sgr A*. I will discuss the implications of this result, and how it may provide insights into evolution history of Sgr A* and our own Galaxy.
	Weimin   Yuan
	Shuang-nan   Zhang	Highlights of Insight-HXMT Results and the Future eXTP Mission In this talkI will first review some highlights of the scientific results of Insight-HXMT,China’s first X-ray astronomy satellite launched on June 15th, 2017. I will then introduce the future mission eXTP (enhanced X-ray Timing and Polarimetry), planned for launch around 2028, to explore the physics under the extreme conditions of gravity, magnetism and density by making precise observations of black holes and neutron stars with simultaneous X-ray timing, spectroscopy and polarimetry.
	Ning   Zhou	Dark matter direct detection with PandaX experiment Located at the China Jinping Underground Laboratory, the PandaX experiment employs xenon as a target to detect rare physics signals, such as dark matter and neutrinos. The PandaX-4T, the latest generation detector featuring a 4-ton xenon target volume, commenced data collection in 2020. One of our objectives is to unravel the nature of dark matter by investigating various potential signatures. In this talk, I will present the most recent results of the dark matter search using the PandaX-4T physics run data, and also give a brief overview of the future prospects of the PandaX experiment.
	Ze-Bing   Zhou	Inertial sensor for TianQin project TianQin is a Chinese space-borne gravitational wave detector proposed in 2014, and aims to detect gravitational waves in the frequency range of 1mHz ~ 1 Hz, with three earth orbiting satellites with an orbital radius of about 105 km forming an equilateral triangle with side length 1.7×105 km. The free falling test masses are used as inertial references to provide measurement points for intersatellite laser interferometry, and also to guide the micro-thrusters control the spacecrafts to follow up them. The residual acceleration noise in the direction of the sensitive axis (intersatellite link) must be not exceed 10-15 m/s2/Hz1/2 within the detection band for TianQin. In this talk, firstly I will introduce the TianQin mission, and then present the requirement analysis and preliminary design of inertial sensor, finally give current progresses and its verification on the ground and in flight.