Jul 7 – 12, 2024
Aurum, the ‘Gabriele d’Annunzio’ University and ICRANet
Europe/Rome timezone

Confirmed plenary speakers


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.


Cosmology and fundamental physics with next-generation GRB observatories

The huge luminosity, the redshift distribution extending at least up to z~10 and the association with the explosive death of very massive stars make long GRBs extremely powerful probes for investigating the early Universe (pop-III stars, cosmic reionization, SFR and metallicity evolution up to the “cosmic dawn”) and measuring cosmological parameters. At the same time, GRBs are expected to be the most prominent electromagnetic counterpart of gravitational-wave sources like NS-NS and NS-BH merging events, and to be associated with neutrino emission. Moreover, the combination of extreme distances, huge number of photons emitted over wide photon energy range and the variability down to few ms makes these phenomena a promising tool for performing tests of fundamental physics like Lorentz Invariance Violation (LIV). I review the status, concepts and expected performances of space mission projects, as THESEUS, aiming at fully exploiting these unique potentialities of the GRB phenomenon, thus providing an ideal synergy with the large e.m. facilities of the future like LSST, ELT, TMT, SKA, CTA, ATHENA in the e.m. domain, advanced second generation (2G++) and third generation (3G) GW detectors and future large neutrino detectors (e.g., Km3NET). 


Carlos Argüelles

Dark matter in galactic structure

The nature of dark matter (DM) is one of the most relevant questions in modern astrophysics. I will present a brief overview of recent results that inquire into a possible fermionic quantum nature of the DM particles, focusing mainly on the interconnection between the microphysics of the neutral fermions and the macrophysical structure of galactic halos. I will show how such an interconnection when analyzed through a first principle physics model based on statistical mechanics and thermodynamics of self-gravitating fermions, leads to a richer core-halo structure for the DM halos than the one obtained from N-body simulations. I will discuss the many distinct applications of such a fermionic model both on halo scales -including morphology constraints from rotation curves and stellar streams- all the way to galaxy center scales -including the case of SgrA* and supermassive BH formation-. In particular I will highlight the possibility that the Milky Way center harbors a dense DM fermion-core instead of a supermassive black hole (SMBH), as well as the role of baryons and the possibility to cause an induced collapse into a massive BH. Further details of each application will be given in different parallel sessions of this Meeting. 

Abhay Ashtekar

On the Quantum Nature of the Coulombic Interaction

The interface between Quantum Information and Quantum Field Theory --especially Quantum Gravity -- is emerging as a forefront area of fundamental physics. But there is some tension between the way the basic concepts are commonly understood by the two communities. In particular, are the `Coulombic modes' of the gravitational field sourced by quantum matter quantum mechanical? They are not registered in the usual Hilbert spaces Hgrav (and Hph) of gravitons (and photons) that know only about the `radiative modes'. Will the proposed experiments directly test the quantum nature of the `radiative aspects' or `Coulombic aspects'? The talk will examine such elementary yet fundamental issues by drawing on an exactly soluble, non-perturbative quantum gravity model that is especially well-suited for this purpose.


Exploring uncharted horizons of astrophysical binary black holes

In this talk, we will explore the theoretical foundations of binary black holes and the revolutionary simulations in numerical relativity that have deepened our understanding of these objects. We will also showcase the remarkable achievements in observational astronomy made possible by gravitational wave observations, which have not only confirmed the existence of binary black holes but have also provided invaluable information about their characteristics, such as mass, spin, and environment. Additionally, we will discuss the potential for electromagnetic observations of binary black hole mergers and the insights they can offer, especially concerning gravitational wave recoils predicted by numerical relativity simulations.
Looking ahead, we will address the exciting prospects made possible by upcoming astronomical facilities, advanced gravitational wave observatories, and space missions like LISA. These advancements will enable us to penetrate further into the cosmos and uncover even more intriguing binary black hole systems. It cannot be overstated how important theoretical calculations are in bridging observational data with the underlying physics. We will delve into the challenges associated with these calculations, from the intricacies of computational methods to the complexities of understanding the physics underlying these phenomena. Furthermore, we will highlight ongoing efforts to develop modern computational tools that will enhance our understanding and improve the accuracy of binary black hole modeling, with a particular focus on simulating accreting supermassive binary black holes and their behavior and interactions.


KAGRA, LIGO, VIRGO observations

After the first groundbreaking observation of gravitational waves emitted by the collision of two black holes on 14 September 2015, the LIGO-Virgo-KAGRA network has completed three successful observing runs yielding nearly a hundred events. All detections were compatible with short transients emitted by the coalescence of compact binaries composed of black holes and/or neutron stars. The first half of the fourth observing run, which took place from May 2023 to January 2024, brought 81 new high-confidence gravitational wave candidates. This number has been steadily increasing since the LIGO and Virgo interferometers have resumed observations after a mid-run break of a few months. The ongoing run has already made new and fascinating discoveries. The talk will summarise the main observational results obtained by the current network of gravitational wave detectors until now.


Repeating Transients from Centers of Galaxies as Extreme Mass Ratio Binaries

Extreme Mass Ratio binaries are systems containing a massive black hole (>10,000 Msolar) and a closely orbiting smaller object (0.1-1000 Msolar). If the companion is also a compact object they can produce gravitational waves potentially detectable with the space-based detectors that will start operating in the next decade. The identification of electromagnetic counterparts of such gravitational wave emitters will transform our understanding of supermassive black hole growth, probe dark energy, and put fundamental constraints on gravity. I will present an overview of the various flavors of repeating transients in galactic centers that we have identified using multi-wavelength studies of several classes of astrophysical transients including stellar tidal distribution events, outbursts from active galactic nuclei (AGN), quasi-periodic eruptions, and quasi-periodic outflows, as seen for the first time by our group. I will also present state-of-the-art general relativistic hydrodynamic simulations of objects embedded in accretion disks around supermassive black holes as a potential model to unify various flavors of repeating transients. I will argue that in some cases these repeating transients could be double compact object binaries with direct implications for multi-messenger astronomy. I will end by highlighting the prospects they hold for the coming decade.


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. 


Fresh results (and surprises) from the James Webb Space Telescope

In less than two years since the release of the first data, the James Webb Space Telescope has revolutionised our knowledge and understanding of the Universe. Thanks to its unprecedented collecting area and IR sensitivity, JWST has allowed us to study the atmosphere of exo-planeets, stellar populations in nearby galaxies and galaxies and AGNs up to z~15 . In my talk I will review the status of the field, describe some of the latest results, first touching a couple of high impact results on exoplanets and resovled nearby stellar populations, and then focusing in particular on those related to the evolution of galaxies and AGNs in the first Gyr after the Big Bang. For these, the emerging picture is extremely exciting, as it combines confirmations - with galaxies showing an evolution off their rest frame properties as we approach the Big Bang - and surprises, like the slower-than-expected evolution of galaxies beyond z~10 and the large fraction of AGNs that are being detected. I will conclude with the potential impact of these discoveries on the fundamental physics and cosmology.

Reinhard Genzel

Experimental Studies of Black Holes: Status & Prospects

More than a century ago, Albert Einstein presented his general theory of gravitation. One of the predictions of this theory is that not only particles and objects with mass, but also the quanta of light, photons, are tied to the curvature of space-time, and thus to gravity. There must be a critical mass density, above which photons cannot escape. These are black holes. It took fifty years before possible candidate objects were identified by observational astronomy. Another fifty years have passed, until we finally can present detailed and credible experimental evidence that black holes of 10 to 1010 times the mass of the Sun exist in the Universe. Three very different experimental techniques have enabled these critical experimental breakthroughs. It has become possible to investigate the space-time structure in the vicinity of the event horizons of black holes. I will summarize these interferometric techniques, and discuss the spectacular recent improvements achieved with all three techniques. In conclusion, I will sketch where the path of exploration and inquiry may lead to in the next decades.


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.


General Relativity meets Geodesy

The intersection of General Relativity and geodesy represents a new frontier in Earth sciences. A major task of geodesy is to determine the gravity field of the Earth, e.g. to monitor mass variations. Due to recent advancements in high precision clock comparison, General Relativity introduced an entirely new measurement concept to geodesy based on the gravitational redshift. We present the basics of a genuinely general relativistic framework for geodesy, generalising the traditional (post-)Newtonian geodetic concepts. Moreover, we outline the exciting applications of clocks on ground and in space for gravity field recovery, reference systems, synchronisation, and tests of General Relativity.


Victoria  Kaspi

Fast Radio Bursts and the CHIME/FRB Project

Fast Radio Bursts are millisecond-duration bursts of radio waves arriving generally from cosmological distances.  Their nature remains unknown.  Here I will review the latest on what is known about this mysterious phenomenon, concentrating on what has been learned from the CHIME telescope, a digital radio telescope operating in Canada, that offers an unprecedented view of the FRB population.





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.


Current status of DECIGO and B-DECIGO

DECIGO (DECi-Hertz Gravitational-wave Observatory) and B-DECIGO are interferometric satellites expected to be launched in Japan around the 2030s targeting the observation of gravitational waves (GWs) from 0.1 Hz to 10 Hz. These missions will unveil populations of intermediate-mass black hole mergers, provide frequent opportunities to localize the host galaxy of a binary neutron star before its merger, and ultimately, directly observe stochastic GWs originating from cosmic inflation. In this talk, the current status of DECIGO and B-DECIGO is presented along with their basic configurations. Additionally, key components that have been studied so far are reported, such as sensitivity trade-offs and theoretical and experimental demonstrations of intersatellite formation flying.



Black holes in alternative gravity theories

In our quest towards a theory of gravity beyond General Relativity black holes with their strong gravitational fields represent an important testing ground. Among the numerous alternative theories of gravity much work in recent years has focused on a set of scalar-tensor theories, where the scalar field couples to higher curvature terms. The properties of the resulting black holes in such theories may differ distictly from those of the Schwarzschild and Kerr black holes as, for instance, revealed by their shadows or their gravitational wave spectra.


Testing Gravity and quantum mechanics

General Relativity and quantum mechanics are both universally applicable theories and are most important for our present understanding of matter, space and time. Clearly, both theories have to be tested as good as possible. In this talk an overview is given of recent tests of both theories like the Equivalence Principle, equivalence of active and passive gravitational mass, the redshift, the linearity of quantum mechanics, Bell inequality. Due to a lack of the combined understanding of General Relativity and quantum mechanics we lay emphasis on quantum tests exploring the structure of space-time and of the gravitational interaction. This concerns tests using clocks, atoms and photons and also includes many particle systems and entanglement.


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".


Establishing an Evolutionary Picture of Fast Radio Bursts (FRBs)

Human's perception and philosophy of the cosmos depend on our collective sensors. Modern optical sky surveys in the 20th century gave rise to the concept of dynamic Universe, one mysterious manifestation of which is fast radio bursts (FRBs). Look like a radio pulse from a neutron star, the FRBs can be 20 orders of magnitude brighter and, if exist, can be seen as far as redshift of z=10, together with the presumed first generation of galaxies and supermassive blackholes. Showing potential for breakthroughs in astrophysics, the discovery of FRBs was awarded the 2023 Shaw's prize in astronomy. We built the largest radio telescope, namely, the Five-hundred-meter Aperture Spherical radio Telescope (FAST), which has been leading the field of characterizing repeating FRBs ever since the inception of FAST's operation in 2020. With close to 100 FAST-based FRB papers, including 5 on Naturand 2 on Science, we started to reveal the evolution of repeating FRBs. We manage to characterize the environment and potentially the age of an active FRB with a single physical parameter, namely, sigma_RM, which can be derived from observation and reflects the complexity of the plasma enshrouding the FRBs. We are also working on a next generation FRB machine, namely Cosmic Antennae (CA), the aim of which is to increase the discovery rate by orders of magnitude over all current radio telescopes.


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.


Yu-Qing Lou

Magnetized Supermassive Stars and Hypermassive Black Holes 

Using general relativity, we study the equilibirum and stability of stars with quasi-spherical symmetry involving random transverse magnetic fields (RTMF) within an extremely wide mass range including magnetized supermassive stars of millions or ten millions of solar masses. Among others, such magnetized massive stars in proper mass ranges would most likely be the progenitors of black holes within the forbidden mass zone as reported by several LIGO/Virgo observations due to the suppression of electron-positron pair instabilities and would also be  the progenitors of magnetars by empirical reasoning. Separately, we present the study on self-similar dynamic formation of hypermassive black holes (HMBHs -- 10 to 1000 billion solar masses or even higher) and supermassive black holes (SMBHs --  millions to billions of solar masses) within giant mass reservoirs in the Universe including the early universe. Pertinent observations and analyses are discussed.


BIack Holes and Massive Galaxies in the Early Universe

Recent observations with the JWST and ALMA have identified at z > 10 massive star forming galaxies of up to 1011 solar masses that are already quench at z > 3. The very early formation and rapid evolution of massive galaxies produced great surprise, because it is difficult to reconcile with standard ΛCDM predictions. I will show that BH-jet feedback accelerated the formation and evolution of massive galaxies. Since the diameter of the Universe decreases with redshift z as 1/(1+z), the global gas density of the Universe increases with redshift, positive BH-feedback becoming a relevant mechanism in the early Universe. In this context, the existence of massive star formation galaxies at z > 10 that are already quench at z > 3 is not surprising. If the SMBHs of more than 107 solar masses found in quasars up to z = 7 result from rapidly growing BH seeds, I will conclude that BH-jet feedback enhanced the formation and growth of the first stars and galaxies at cosmic dawn.


Bi-twistors: an extension of twistor theory for general space-times

Twistor theory was initially developed to describe the geometry of Minkowski space-time in terms of its null geodesics.  The natural generalization to curved space-times requires the ubiquitous existence of α-surfaces, this requiring the Weyl curvature to be anti-self-dual, which for a real space-time implies conformal flatness.   A bi-twistor, however, incorporates both a twistor and a dual-twistor, together with their canonical commutation relations, and the role of the α-surfaces is simply replaced by that of null geodesics, which are ubiquitous in any space-time. Accordingly, bi-twistor theory can be developed so as to apply to space-times generally.


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.


Recent results from IceCube

IceCube is a cubic kilometer neutrino observatory at the geographic South Pole whose sensitivity from PeV down to GeV, or MeV using a special DAQ, has spawned a diverse scientific program. It discovered and continues to characterize the astrophysical neutrino flux, recently identifying a galactic component. To resolve it further, IceCube has found a 4.2σ excess from the direction of NGC 1068 and continues to target a variety of source candidates, both above and below 1 TeV. IceCube maintains several programs for real-time alerts and follow-ups. The background of events caused by particles from cosmic ray air showers in itself enables the study of cosmic ray and neutrino physics, in particular neutrino oscillations. IceCube further makes significant efforts towards physics beyond the Standard Model such as searching for quantum gravity. This talk highlights results since the previous Marcel Grossmann meeting in 2021 and provides an outlook on prospects for the planned high-energy extension IceCube-Gen2.


Lesson about gravity from black-hole imaging

I will briefly discuss how the first images of the supermassive black holes M87* and Sgr A* were obtained by the EHT collaboration. In particular, I will describe the theoretical aspects that have allowed us to model the dynamics of the plasma accreting onto the black hole and how the comparison between the theoretical images and the observations on a broad range of frequencies has allowed us to deduce the presence of supermassive black holes and to extract information about the accretion process. In addition, I will describe the lessons we have learned from these imaging process about strong-field gravity and alternatives to black holes.


The Einstein Telescope project: a third generation of Gravitational Wave detector on the Earth.

In the field of gravitational wave (GW) detection, groundbreaking discoveries like those made by the LIGO, Virgo, and KAGRA collaborations signify the culmination of extensive interdisciplinary efforts spanning various research fields. These detectors grapple with numerous noise sources that undermine their sensitivity. To surmount these challenges, we are exploring strategies that harness novel technologies and innovative approaches. The development of third-generation GW interferometers, epitomised by the Einstein Telescope (ET) project, underscores a monumental experimental endeavour.      
In this talk, we will offer an overview of the new experimental challenges facing ET and the strategies proposed to achieve the ambitious advancements in sensitivity. By overcoming these challenges, we aim to unlock unparalleled opportunities to explore the Universe through gravitational waves.



AI in the Cosmos: Application of neural networks for modeling multiwavelength and multimessenger data from blazar observations

The integration of Artificial Intelligence (AI) into astronomy and astrophysics marks a transformative era in the exploration of the Universe, enhancing the analysis of vast data sets with unparalleled efficiency and precision. AI is revolutionizing the usability of observational data, expanding our understanding of various cosmic phenomena. Blazar research particularly benefits from the application of AI. In this talk, I will present a pioneering effort in employing a Convolutional Neural Network (CNN) for the efficient modeling of blazar emissions. Blazars are among the most powerful extragalactic sources, emitting across the entire electromagnetic spectrum, from radio to very high-energy gamma-ray bands. As significant sources of non-thermal radiation, blazars are frequently monitored by various telescopes, leading to the accumulation of substantial multi-wavelength data over different time periods. Also, over the years, the complexity of models of blazar emission has dramatically increased which hinders parameter exploration and makes data interpretation through model fitting challenging. By training the CNN on lepton-hadronic emission models generated for a set of models computed with the kinetic code SOPRANO, which considers the interaction of initial and all secondary particles, the resultant CNN can accurately model the radiative signatures of electron/proton interactions in relativistic jets. This CNN-based approach significantly reduces computational time, thereby enabling fitting to multi-wavelength (photons) and multi-messenger (neutrinos) datasets. The adoption of this AI-driven methodology enables self-consistent modeling of blazar emissions, offering profound insights into their underlying physics and potentially uncovering new astrophysical phenomena. I will present and discuss several results where these networks have been used to model multi-wavelength, multi-temporal data from blazar observations.


Do we understand cosmic structure growth? Insights from new CMB lensing measurements with the Atacama Cosmology Telescope

One of the most powerful tests of our cosmological model is to verify the predicted growth of large-scale structure with time. Intriguingly, many recent measurements have reported small discrepancies in such tests of structure growth ("the S8 tension"), which could hint at systematic errors or even new physics. Motivated by this puzzling situation, I will present new determinations of cosmic structure growth using CMB gravitational lensing measurements from the Atacama Cosmology Telescope (ACT). These ACT DR6 CMB lensing measurements allow us to directly map the dark matter distribution in projection out to high redshifts; new cross-correlations of CMB lensing with unWISE galaxies also allow us to probe the matter tomographically. I will discuss the implications of our lensing results for the validity of our standard cosmological model as well as for key cosmological parameters such as the neutrino mass and Hubble constant.


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.


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.


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.

Yu Wang

Can AI Understand Our Universe? 

ChatGPT has been a highly discussed topic recently, capturing the attention of both professionals and the general public. It has sparked conversations about the impact of artificial intelligence (AI) on the world. As physicists and astrophysicists, we are interested in whether large language models (LLMs) can accurately analyze scientific data and produce valid physics results. In this article, we fine-tune the generative pre-trained transformer (GPT) model using astronomical data. We demonstrate a single model’s ability to understand multiple astronomical data sets, exemplified by its classification of astrophysical phenomena, distinction between types of gamma-ray bursts (GRBs), deduction of the redshift of quasars, and estimation of black hole (BH) parameters. We consider this a successful test, proving the LLM’s efficacy in scientific research. This shift moves us from specialized knowledge in various areas to an integrated understanding, offering deeper and more connected insights into how the natural world works. It signals the start of a new phase in scientific research.


Progress of Taiji Program and Nature of Gravity & Spacetime

Taiji is a Chinese space mission to detect gravitational waves with frequencies covering the range of 0.1mHz to 1.0Hz by utilizing a triangle of three spacecrafts in orbit around the Sun, which aims to probe the super (intermediate) mass black hole merges and extreme (intermediate) mass ratio in-spirals, to study the most challenging issues concerning the origin and evolution of massive black holes and universe, and to explore the nature of gravity and spacetime as well as dark side of the universe. In this talk, I am going to introduce briefly Taiji’s mission, scientific objectives and payload design, and present a brief report on Taiji’s roadmap with the testing result of Taiji-1, the current status of Taiji-2 and the prospection of Taiji-3. I will also bring a discussion on the nature of gravity and spacetime beyond the general relativity and Riemannian geometry, which enables to establish gravitational quantum field theory (GQFT) to combine consistently the general relativity and quantum field theory, and to unify all basic forces within the framework of GQFT.


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.


The Einstein Probe mission

Launched on January 9th, 2024, the Einstein Probe (EP) is a space X-ray observatory designed to detect mainly high-energy transient and variable sources in the universe. It aims at detecting such sources at unprecedented sensitivity and spatial resolution in the soft X-ray band and performing quick onboard follow-up observations in X-rays. EP carries two instruments, a wide-field X-ray telescope (WXT) to monitor the soft X-ray sky in 0.5-4keV with a 3600 square-degree field-of-view, and a narrow-field follow-up X-ray telescope (FXT) in 0.3-10keV. The WXT is an imaging telescope making use of novel X-ray focusing technology of lobster-eye micro-pore optics. Transient alerts can be downlinked quickly to ground to trigger follow-up observations at multi-wavelengths. The Einstein Probe is a project led by the Chinese Academy of Sciences in collaboration with ESA, MPE and CNES. Since its launch, the satellite has been in the commissioning phase, during which a series tests on the spacecraft and the instruments, and in-orbit calibration are carried out. During this phase a number of X-ray transients have been detected by EP and extensively followed up and studied by the EP science team and by the wider community. This talk will introduce the mission, its status, the instrument performance and preliminary results of the transient sources detected. 


Highlights of Insight-HXMT Results and the Future eXTP Mission

In this talk 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.


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.




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.