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chris done (university of Durham)07/09/2026, 12:00
I will review observations and theory of winds in accreting binaries.
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Ali Alpar (Sabanci University)07/09/2026, 12:30
The determination of the inner radius of an accretion disk needs to take into account the rotation rates of the disk and the neutron star and the angular momentum exchange between the disk and the star. When angular momentum is taken into account, with conditions to accrete or expel matter, the inner radius is found to lie closer to the corotation radius, rather than the Alfven radius,...
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Mr Andrzej Zdziarski (N. Copernicus Astronomical Center)07/09/2026, 12:45
The structure of X-ray sources in the hard spectral state of accreting black hole binaries has been a subject of intense debate for many years. There are two main scenarios. In one, the accretion disk disappears below a certain radius and is replaced by a hot flow that emits hard X-rays. In the other, the disk continues to the innermost stable circular orbit, and the hard X-ray source is...
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Montserrat Armas Padilla (Instituto de Astrofísica de Canarias (IAC))07/09/2026, 15:00
The geometry and physical conditions of black hole accretion discs are expected to change dramatically as a function of mass accretion rate and the resulting X-ray luminosity. Theoretical models predict that these changes become particularly relevant as the luminosity approaches the Eddington limit (LEdd), a regime where the standard thin-disc solution is thought to break down in favour of...
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Fergus Baker (Durham University)07/09/2026, 15:15
X-ray reverberation lags probe the light travel time due to relativistic curvature effects in the reflected emission close to black holes, and can be used to measure properties of the accreting system, including the mass of the central compact object. Existing models for X-ray reverberation lags and relativistically blurred reflection spectra are, however, limited by their treatment of coronal...
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Nathalie Degenaar (University of Amsterdam)07/09/2026, 16:30
X-ray binaries exhibit a rich phenomenology of accretion states and transitions, linking changes in the accretion flow to the production of jets, winds, and high-energy emission across a wide range of timescales. In this talk, I will review our current understanding of accretion states and state transitions in neutron star and black hole X-ray binaries, highlighting recent observational...
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Amy Knight (Durham University, UK)07/09/2026, 17:00
After sixteen years in quiescence, EXO 0748-676 unexpectedly alerted the world to its return to outburst with a bright X-ray burst in June 2024, having been increasing in brightness since March 2024. However, in stark contrast to its previous outburst (1985 - 2008), EXO 0748-676 returned to quiescence in January 2025, after roughly 10 months in outburst. In this talk, I will present a...
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Jorge Casares (Instituto de Astrofisica de Canarias)07/09/2026, 17:15
The Milky Way is thought to be populated with ~103-104 stellar-mass black holes (BHs) that are fed by gas accreted from companion stars in tight orbits. Most of these BHs are transient and exhibit episodic X-ray outbursts on decadal timescales - the smoking gun that led to their discovery. However, since their duty cycles are very low, the vast majority remain hidden in a dormant state,...
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Marco Maria Messa (Istituto Nazionale di Astrofisica (INAF))07/09/2026, 17:30
Transitional millisecond pulsars (tMSP) represent a dynamic category of celestial sources that establish a crucial connection between low-mass X-ray binaries and millisecond radio pulsars. These systems exhibit transitions from rotation-powered to accretion-powered states and vice versa, highlighting the tight evolutionary link expected by the so-called recycling scenario. In their active...
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Federico Vincentelli (Coventry University)08/09/2026, 09:30
Since the early X-ray timing studies, it has been known that both Black hole and Neutro stars X-ray binaries show narrow quasi-periodic oscillations between 0.01 and 100 Hz. Despite decades of studies, the physical origin of this intriguing phenomenon remains uncertain. In this talk I will review the main observational properties of these oscillation for both classes of systems, and describe...
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Suchismito Chattopadhyay (Inter-University Centre for Astronomy and Astrophysics)08/09/2026, 10:00
Type-I thermonuclear bursts (TNBs) in neutron star low-mass X-ray binaries arise from unstable nuclear burning on the neutron star surface, whereas kHz quasi-periodic oscillations (QPOs) are believed to originate in the innermost regions of the accretion disk. The intense radiation released during a Type-I burst can perturb the inner accretion flow and thereby affect the kHz QPOs. Using 3–20...
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Mr Federico Ferretti (Università degli Studi Roma Tre, Universitat Politecnica de Catalunya)08/09/2026, 10:15
GX 339–4 is a low-mass X-ray binary often used as an archetype, showing typical outburst behaviour. The source undergoes a full outburst every 2–3 years, passing through all known accretion states. We used NICER data to study the spectral-timing properties of the 2024 outburst of GX 339–4 and to compare them with the 2021 outburst. In particular we focused on rapid “flip-flop” transitions,...
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Mrs Kateřina Klimovičová (Silesian university in Opava)08/09/2026, 10:30
Confronting observational measurements with theoretical models of neutron star spacetimes presents several challenges. These are particularly pronounced due to the differences in the definitions of measurable physical quantities and the quantities commonly used to define the spacetime metric, with the dependence of these quantities on the NS equation of state playing a major role. Here, we...
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Kewal Anand (Indian Institute of Technology Kanpur, India)08/09/2026, 10:45
We report simultaneous detection of twin kHz and $\sim 40$ Hz quasi-periodic oscillations (QPOs) in the time-resolved analysis of the AstroSat/LAXPC observation of the neutron star low mass X-ray binary, 4U 1728-34. We present the first robust detection of multiple sets of QPO triplets from a single observation whose frequencies are mutually correlated and consistent with their identification...
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Pei Jin (Kapteyn Astronomical Institute)08/09/2026, 11:30
Black hole X-ray binaries are key laboratories for studying the behavior of matter in strong gravitational fields. During outbursts, these systems evolve through different spectral-timing states, whose distinct properties suggest changes in the geometry of the accretion flow. Previous studies have shown that the transition from the hard-intermediate state to the soft-intermediate state is...
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Prof. Luigi Stella (INAF Rome Astronomical Observatory)08/09/2026, 11:45
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Andrea Comastri (Istituto Nazionale di Astrofisica (INAF))08/09/2026, 12:00Talk
In the early 90s, right after the ROSAT launch, MPE was a busy place visited by many scientists, young postdocs, and students. Too many to be accommodated in the offices of the X-ray group in the main building. Temporary containers with small offices were installed, and the fraction of Italians was particularly high in one of them.
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We will make an effort to remember a few significant... -
Barbara De Marco (Universitat Politècnica de Catalunya)08/09/2026, 12:15
Black hole X-ray binaries (BHXRBs) provide an exceptional laboratory for studying the physics of accretion under strong gravity. In particular, energy-dependent variability and X-ray time lags carry key information about the geometry, dynamics, and evolution of the accretion flow. In this talk, I will review the current state-of-the-art in spectral-timing studies of BHXRBs, focusing on how...
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Nick Kylafis (Institute of Astrophysics, FORTH, Crete)08/09/2026, 12:45
It is well accepted by our community that the hard X-ray spectra in black-hole X-ray binaries (BHXRBs) are produced by Comptonization of soft photons. It is also well known that Comptonization produces timelags. This is because the more the soft photons are scattered, the more their energy is increased, the larger the random walk that they do in the scattering medium, and the larger their...
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Andrea Sanna (Istituto Nazionale di Astrofisica (INAF))08/09/2026, 15:00
Low-mass X-ray binaries are interacting systems in which a compact object accretes matter from a low-mass companion star, releasing most of its energy in the X-ray band. When the compact object is a neutron star, these systems provide unique laboratories to investigate accretion physics under extreme conditions of gravity, density, and magnetic field strength.
Among them, accreting...
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Seth Larner (Washington University, St. Louis MO, USA)08/09/2026, 15:15
The black hole X-ray binary Cygnus X-1 exhibits high levels of variability spanning many decades in frequency across all of its spectral states. This broad band variability power is comprised of several distinct components evolving in concert as the source changes states. The amplitudes, frequencies, and energy dependent lags of these components reveal information about the physical accretion...
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Gabriel Török (Silesian University in Opava)08/09/2026, 15:30
Quasi-periodic oscillations (QPOs) in the X-ray variability of accreting neutron stars provide key insights into accretion in strong gravity and the equation of state of dense matter (EoS). We discuss the possible precession origin of twin-peak QPOs, focusing particularly on two specific models. The first is the relativistic precession model, which links QPO frequencies to the frequencies of...
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Federico Garcia (Instituto Argentino de Radioastronomia (IAR-CONICET))08/09/2026, 15:45
The study of X-ray binaries has been fundamentally transformed by spectral-timing techniques, which bridge the gap between energy spectra and fast variability to map the innermost regions of accreting compact objects. By exploring the complex interplay between photons of different energies and their arrival times, these methods provide unique constraints on the geometry, dynamics, and physical...
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Dr Eleonora Veronica Lai (INAF - OAC)08/09/2026, 16:45
X-ray binaries are unique laboratories for studying the physics of accretion processes. They exhibit variability over a wide range of timescales, providing key information on the physics of compact objects and their surroundings.
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Stingray is an open-source Python library designed to perform time series analyses and related tasks on astronomical light curves with a focus on X-ray astronomy.... -
Erik Kuulkers (ESA/ESTEC)08/09/2026, 17:15Talk
Tomaso and I were the first post-doc and PhD student, respectively, of Michiel van der Klis when he became professor at the API in Amsterdam. Afterwards, in time at various meetings we interacted and even combined our research interests, especially related to (absorption) dips in the light curves of black-hole X-ray binaries.
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In a paper in 1996, Tomaso with colleagues reported on an... -
Guglielmo Mastroserio (IUSS Pavia)09/09/2026, 09:30
The rich phenomenology displayed by transient black hole X-ray binaries during outbursts offers a powerful probe of accretion physics. I will summarize our current understanding of the evolution of the X-ray spectrum across accretion states, with particular emphasis on the changing geometry of the inner accretion flow as traced by the thermal, Comptonized, and reflection components. The...
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rosario iaria (DiFC - UNIPA)09/09/2026, 10:00
We report the detection of a mysterious absorption feature at approximately 3.8 keV in the Neutron star Interior Composition Explorer (NICER) spectrum of the ultracompact low-mass X-ray binary 4U 1820–30. We interpret this feature as a gravitationally redshifted iron absorption line produced in the vicinity of the neutron-star surface. This scenario is supported by the temporal proximity of...
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Rob Fender (University of Oxford)09/09/2026, 10:15
I will review the current state of our understanding of accretion and ejection in black hole X-ray binaries. While I will keep the talk current and topical I will also reflect on how working with Tomaso Belloni brought a much fuller understanding of accretion to someone trained in radio astronomy, and how looking beyond one's silo is almost always worth it.
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Julien Malzac (IRAP (CNRS / Universite de Toulouse))09/09/2026, 10:45
We investigate the radio to MeV spectral energy distribution (SED) of the proto typical stellar-mass black hole, Cygnus X-1.
We model the SED by combining the jet Internal Shocks Emission Model (ISHEM) with the JED-SAD model (Jet Emitting Disk – Standard Accretion Disk) which links accretion and ejection.During the fitting procedure the jet kinetic power and average Lorentz factor of the...
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Francesco Carotenuto (Istituto Nazionale di Astrofisica (INAF))09/09/2026, 11:30
Black hole X-ray binaries (BH XRBs) launch powerful outflows in the form of radio-emitting discrete jet ejecta, which are observed to be produced during outburst phases, at the transition between different accretion states. Once spatially resolved, these components are observed to propagate up to parsec scales far from the BH, often displaying apparent superluminal motion. However, little is...
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Katherine Savard (University of Oxford)09/09/2026, 11:45
Discrete ejecta from X-ray binaries are crucial for understanding jet physics from event horizon to parsec scales: launched during accretion state transitions, they probe the link between the accretion flow and jet launching, and then propagate up to $10^11$ gravitational radii, efficiently distributing mass and energy through their interaction with the ISM. Understanding how massive these...
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Isabella Mariani (Istituto Nazionale di Astrofisica (INAF))09/09/2026, 12:00
X-ray binaries (XRBs) hosting a stellar-mass black hole (BH) or neutron star produce strong emission through accretion of matter from a companion star onto the compact object. This process can also lead to the formation of fast, collimated outflows, called jets. Most BH-XRBs are transient systems, producing steady compact jets during quiescence and hard X-ray states, and discrete ejecta...
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Pau Bosch Cabot (University of Lethbridge)09/09/2026, 12:15
Outflows from compact objects and massive stars play a key role in shaping the interstellar medium through injecting significant amounts of energy and momentum. The visible imprints that outflows produce on sites where they impact the interstellar medium allow them to act as natural calorimeters, providing a way to quantify the energy required to form and maintain them. High-mass X-ray binary...
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Dr Rosaria Bonito (INAF)09/09/2026, 12:30
Women are still underrepresented in senior positions in astronomy, even though their academic performance is comparable to, and sometimes better than, that of their male colleagues. This is the well-known pattern of vertical segregation that INAF’s Gender Equality Plans aim to address.
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In this contribution, we place INAF’s response within the broader international context.
Studies of... -
Dr Teo Muñoz-Darias (Instituto de Astrofisica de Canarias)09/09/2026, 15:00
X-ray binaries offer a unique opportunity to study accretion in relatively clean environments and on human-accessible timescales, much shorter than those typical of AGN and quasars. Over the past few decades, the coupling between accretion and ejection processes in these systems has been extensively investigated, primarily through X-ray and radio continuum observations. More recently,...
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Daniel Mata Sanchez (IAC)09/09/2026, 15:30
Optical spectroscopy has become a powerful probe of accretion and ejection in outbursting low-mass X-ray binaries. Over the past decade, outflow signatures once confined to X-rays have been routinely identified at optical, near-infrared, and ultraviolet wavelengths, establishing a new framework for investigating accretion-disc winds and their connection to the accretion flow. Canonical optical...
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Sara Peluso (ESO)09/09/2026, 15:45
Ultra-Compact X-ray Binaries (UCXBs) are a subclass of neutron star low-mass X-ray binaries (NS-LMXBs) characterized by very short orbital periods ($P<80$ min) and compact system sizes, making them ideal systems for probing the properties of accretion disks, in particular the structure and kinematics of winds and outflows. The detection of wind features in X-ray spectra is not always...
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Dave Russell (New York University Abu Dhabi)09/09/2026, 16:30
X-ray binaries radiate brightly from radio to X-ray due to the accretion and ejection of matter in the system. Complex, correlated flux variations probe links between emitting components, on short as well as long timescales. Here I review the progression of multi-wavelength studies of X-ray binaries, focusing on long-term (day+ timescales) correlated behaviour between radio, optical/infrared...
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Justine Crook-Mansour (University of OXford)09/09/2026, 17:00
During the hard and quiescent spectral states in X-ray binaries, a non-linear correlation is observed between radio and X-ray luminosities, providing a valuable tool to probe the connection between accretion and jet production. This relation was originally thought to define a single ‘standard’ correlation spanning several orders of magnitude in X-ray luminosity, and was extended to active...
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Piergiorgio Casella (Istituto Nazionale di Astrofisica (INAF))09/09/2026, 17:15
Fast multiwavelength variability is a key tool for studying the coupling between accretion flows and relativistic jets in X-ray binaries, providing unique insights into the physical processes governing jet launching and energy dissipation in the innermost regions around compact objects. In this talk, I will review the current observational and interpretative landscape, highlighting recent...
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Dr Sandro Mereghetti (Istituto Nazionale di Astrofisica (INAF))09/09/2026, 17:45
The source 1A 0538-66, located in the Large Magellanic Cloud, contains the fastest-spinning neutron star in an accreting X-ray binary and shows a combination of extreme properties unmatched in other NS/Be systems.
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It is characterized by extraordinary multiwavelength variability, including sporadic episodes of seconds-long X-ray flares with a dynamic range >1000 and peak luminosities... -
Dr Alex Tetarenko (University of Lethbridge)09/09/2026, 18:00
Black hole X-ray binaries are accreting objects that launch powerful relativistic jets. These systems evolve through bright outburst phases on timescales of days to months, allowing us to probe jet and accretion phenomena in real-time. As X-ray binaries produce highly variable emission, time-series observations can be a powerful tool to study these systems. However, as these systems emit...
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Caterina Ballocco (Istituto Nazionale di Astrofisica (INAF))09/09/2026, 18:15
SAX J1808.4-3658 is the prototype of accreting millisecond X-ray pulsars and the first of this class to show optical and UV pulsations during an accretion outburst. These pulsations challenge standard rotation- or accretion-powered scenarios and provide a unique window into the emission mechanisms of pulsating neutron stars.
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I will present a multi-band timing study based on XMM-Newton,... -
Andrea Comastri (Istituto Nazionale di Astrofisica (INAF))10/09/2026, 10:00
Deep JWST surveys have revolutionized our knowledge of the formation and early evolution of Active Galactic Nuclei at the cosmic dawn.
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Webb uncovered a large population of compact Broad Lined AGN with moderate luminosities, log LBOL ~ 42-45, high redshifts, z > 4, and black holes’ inferred masses 106-8 MSUN. A subclass exhibits red, V-shaped UV-optical continua and is commonly classified as... -
Edwin Santiago (Instituto Nacional de Astrofísica, Óptica y Electrónica)10/09/2026, 10:30
Since the Laser Interferometer Space Antenna (LISA) project was announced, interest in binary systems of supermassive black holes (SMBHBs) has grown, as it is expected that these systems will be observable with this instrument. In particular, efforts have been made to produce realistic simulations of SMBHBs surrounded by a circumbinary disk (CD), since this specific scenario could be the...
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Dr Ciro Pinto (Istituto Nazionale di Astrofisica (INAF))10/09/2026, 11:45
Most stars in galaxies reside in binary systems, many of which are interacting and powered by matter transfer onto a compact object. The brightest and most extreme among these systems are ultraluminous X-ray sources (ULXs). Reaching luminosities well above $10^{41}$ erg/s, ULXs routinely breach the classical Eddington limit of stellar-mass objects, making them the "enchanted kingdom" of...
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Chiara Salvaggio (Istituto Nazionale di Astrofisica (INAF))10/09/2026, 12:15
Ultraluminous X-ray sources (ULXs) are a class of extreme X-ray binaries, most of them powered by super-Eddington accretion onto stellar mass black holes and neutron stars. Extended optical or radio emission (and a single case in X-rays) has been observed around some ULXs, with a bubble-like shape. These huge bubbles have diameters > 100 pc and contain an energy 10-100 times larger than the...
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Dr Matteo Bachetti (Istituto Nazionale di Astrofisica (INAF))10/09/2026, 12:30
The M82 galaxy harbors two of the most interesting ultraluminous X-ray sources (ULXs) -- off nuclear point sources radiating above the Eddington limit for a typical stellar remnant black hole.
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Some ULXs might be sub-Eddington intermediate-mass black holes, but the bulk of this class is now widely believed to be powered by super-Eddington accretion onto compact objects.
In a handful of cases,... -
Anna Wolter (Istituto Nazionale di Astrofisica (INAF))10/09/2026, 12:45
Ring galaxies (RiGs) represent a particularly favorable environment for the formation of Ultra Luminous X-ray sources (ULXs). These systems are produced by a cosmic crash between a disk galaxy and a smaller companion, generating an expanding density wave that compresses the interstellar medium and triggers intense star formation along a ring. The archetypal Cartwheel galaxy and several other...
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Dr Rosaria Bonito (INAF)10/09/2026, 15:00
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Alexandra Veledina (University of Turku)10/09/2026, 15:30
I will review the first results of X-ray polarimetry in accreting X-ray binary systems, focusing on the puzzles and challenges to the models of accretion they posed, along with potential ways towards the solutions.
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Maria Cristina Baglio (Istituto Nazionale di Astrofisica (INAF))10/09/2026, 16:30
Low-mass X-ray binaries are perfect laboratories for studying accretion physics and its coupling with jets and outflows. The advent of X-ray polarimetry with IXPE has opened a new window onto the geometry of the innermost accretion regions, yet a complete physical picture demands a broader, multi-wavelength perspective.
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I will show how optical polarimetry provides an important complementary... -
Juri Poutanen (University of Turku)10/09/2026, 16:45
The launch of the Imaging X-ray Polarimetry Explorer (IXPE) marked a major advance in X-ray astronomy by enabling measurements of X-ray polarization from compact astrophysical objects. In accreting black holes, polarization provides a powerful tool for probing the geometry of the emitting region and constraining the black hole spin.
IXPE measured a polarization degree of about 2% in Cygnus...
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Romana Mikusincova (Istituto Nazionale di Astrofisica (INAF))10/09/2026, 17:00
We present the first X-ray polarimetric measurement of the eclipsing neutron star low-mass X-ray binary system AX J1745.6-2901 obtained with the Imaging X-ray Polarimetry Explorer (IXPE). This transient source lies within ∼1.5′ of the Galactic center and was observed serendipitously during a 150 ks IXPE pointing at MAXI J1744-294. The crowded and highly absorbed Galactic center environment...
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Alessio Anitra (Istituto Nazionale di Astrofisica (INAF))10/09/2026, 17:15
4U 1822-371 is the prototype accretion-disc corona neutron-star LMXB. In this geometry, the direct emission from the innermost regions is obscured by the outer disc rim, and the observed X-ray radiation is dominated by scattering and reprocessing. We present the first X-ray polarimetric detection of 4U 1822--371 and the first simultaneous broadband spectro-polarimetric analysis of the source,...
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Dr Simone Scaringi (Durham University)10/09/2026, 17:30
Accreting white dwarfs (AWDs) are exceptionally bright and relatively abundant in our Galaxy, making them invaluable laboratories for studying both accretion physics and binary evolution. In this talk, I will focus on cataclysmic variables (a subset of AWDs) and discuss how ground- and space-based observations have provided unprecedented detail on their broad-band and quasi-periodic...
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Dr Gianpiero Tagliaferri (INAF Brera Astronomical Observatory)10/09/2026, 18:00
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Prof. Tiziana Di Salvo (University of Palermo)10/09/2026, 18:15
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Joern Wilms (Remeis-Observatory & ECAP, FAU Erlangen-Nuernberg)11/09/2026, 09:30
The past decades have yielded a huge amount of information on the physics of X-ray binaries. The combination of X-ray variability measurements and spectroscopy, which has recently been supplemented with exciting X-ray polarization data, and multi-wavelength observations has allowed us to constrain the accretion flow physics and the phenomenological behavior of these sources. We have also been...
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Prof. Marco Feroci (INAF Brera Astronomical Observatory)11/09/2026, 10:00
The current and planned scenario of the observational capabilities available to the X-ray scientific
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community in the foreeseable future is far from ideal, with ambitious candidate X-ray missions recently not
selected for further developments both in Europe and the US. Yet, new ideas and developments are in place
from Europe to China to India and beyond, trying to design a better... -
Dr Boris Sbarufatti (INAF Brera Astronomical Observatory)11/09/2026, 10:30
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Debora Lančová (Nicolas Copernicus Astronomical Centre, Warsaw, Poland, Institute of Physics, Silesian University in Opava, Czech Republic)Poster
Changing-Look Active Galactic Nuclei (CLAGN) undergo dramatic spectral and luminosity transitions on timescales of months to a few years— orders of magnitude shorter than the viscous timescale of a standard α-disk at the radii where the optical/UV continuum is generated, for typical supermassive black hole masses. We show that a magnetically supported disk-corona model reproduces both the...
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Amy Knight (Durham University, UK)Poster
The discoveries of coherent X-ray pulsations from several known ultraluminous X-ray sources (ULXs) have provided conclusive proof that some ULXs host neutron stars (NSs) accreting at rates far exceeding their nominal Eddington limits, and raised questions concerning the overall contribution of NS accretors to the broader population of ULXs and the physics of super-Eddington accretion that...
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Sara Elisa Motta (Istituto Nazionale di Astrofisica (INAF))Talk
LOC info and a short tribute to Tomaso Belloni
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Enzo Agustin Saavedra (Instituto de Astrofísica de Canarias)Poster
Low-mass X-ray binaries spend most of their lifetimes in quiescence, where accretion occurs at extremely low luminosities and the optical emission is often interpreted as a combination of the donor-star contribution and non-stellar light. A0620–00, the archetypal quiescent black-hole transient, is the best-studied system in this regime. Since its 1975 outburst, the source has remained in X-ray...
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Dr Wasutep Luangtip (Srinakharinwirot University)Poster
Ultraluminous X-ray sources (ULXs) are highly energetic extragalactic objects driven by super-Eddington accretion onto stellar-mass compact objects. While the number of ULXs in normal galaxies scales predictably with the star formation rate (SFR), extreme star-forming environments exhibit a significant deficit of ULXs, with populations falling up to a factor of 10 below expected values. To...
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Dr David Buckley (UCT)Poster
Following on two ISSI-BJ workshops organized by Tomaso Belloni and Dipankar Bhattacharya in 2017 & 2018, with the title “Understanding multi-wavelength rapid variability: accretion and jet ejection in compact objects”, we developed AstroSat anticipated ToO proposals to observe a state transition in a known black hole X-ray binary (BHXB) transient. Three separate, but identical, proposals were...
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Pengcheng Yang (Kapteyn Astronomical Institute, University of Groningen)Poster
Recent studies have revealed a notable timing feature in several black hole X-ray binaries (BHXBs) during the soft-to-hard transition at the outburst decay. Within a narrow frequency range, the phase lags between high- and low-energy X-ray light curves exhibit a sudden increase, accompanied by a drop in the coherence function. These narrow features have been associated with a quasi-periodic...
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Jing XuePoster
The black hole candidate LMC X-1 is a persistently soft-state high-mass X-ray binary with an unusual luminosity--temperature relationship, and its inferred spin depends strongly on assumptions about disk structure and the treatment of the seed-photon spectrum. To investigate the role of Comptonization in shaping its thermal continuum, we analyze 10 Chandra High Energy Transmission Grating...
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Emrah Kalemci (Sabanci University)Poster
We present a framework that combines state-of-the-art three-dimensional general relativistic magnetohydrodynamic (3D GRMHD) simulations with radiative transfer calculations to directly compare theoretical predictions with multiwavelength observations of Galactic black hole transients (GBHT). Using the H-AMR code, we simulate black hole accretion flows in both SANE and MAD magnetic...
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Kaya Mori (Columbia University)Poster
The variability observed in stellar-mass black hole and neutron star binaries is highly complex and non-linear, exhibiting QPOs, stochastic and aperiodic components. Short-term variability, such as rapid flares, is commonly attributed to magnetic reconnection, plasmoid ejection and MHD turbulence, while long-term variability reflects changes in accretion states, jets, coronae, and their...
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Vladislav Revnivtsev (SAI MSU, IKI RAS)Poster
The X-ray pulsar Her X-1 has a number of well-known periodicities, including a $\sim 35$-day superorbital cycle due to precession of a tilted twisted accretion disk around a magnetized neutron star. In addition to precession, the tilted accretion disk should experience tidal nutation (wobbling). We present results of analysis of dedicated SRG/ART-XC observations confirming the accrtetion disk...
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Srimanta Banerjee (Istituto Nazionale di Astrofisica (INAF))Poster
The origin of hard X-ray emission in black hole X-ray binaries during the hard spectral state is commonly attributed to thermal Comptonization in a hot inner flow, yet the possible contribution of jet synchrotron emission remains uncertain. We present a multi-wavelength study of the 2021 outburst of GX 339-4, focusing on five hard-state observations covering luminosities of ~1-10% of the...
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Siham Kalli (M'sila University)Poster
We present a spectral analysis of the Seyfert 1 galaxy Mrk 841, utilizing the longest and most recent XMM-Newton observations with exposures exceeding 100 ks. This highly variable source features a complex iron line profile and a strong soft excess. By fitting a comprehensive model that integrates disk ionization, relativistic effects, and absorption components, we investigate the structure...
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Carlotta Miceli (Universitat Politècnica de Catalunya (UPC))Poster
GRS 1915+105 is one of the most extreme Galactic black hole X-ray binaries, characterized by a quasi-persistent high accretion rates and complex X-ray variability. We present a broadband spectral study of its recent obscured state using a quasi-simultaneous XMM-Newton and NuSTAR observation obtained in July 2021.
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A key result of this analysis is the measurement of a relatively low... -
Mr Kyle Solomons (INAF Brera Astronomical Observatory)Poster
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Wladimiro Leone (Istituto Nazionale di Astrofisica (INAF))Poster
We present a combined spectral and timing analysis of NGC 7456 ULX-1 based on the two deepest available XMM-Newton observations, obtained in 2018 and 2023. Using adaptive-binning cross-correlation techniques optimized for the low-count regime, we detect significant hard X-ray lags of order $\sim10^{3}$ s, with the 1--10 keV emission delayed with respect to the 0.3--1 keV band in both...
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Marcio Guilherme Bronzato de Avellar (Instituto Nacional de Pesquisas Espaciais)Poster
Fast Radio Bursts are usually discussed in terms of magnetospheric emission, relativistic outflows, or compact-object interactions, but their possible connection with accretion-driven variability remains comparatively underexplored. In this contribution, we examine a dynamical channel in which Kozai–Lidov cycles in hierarchical compact triples periodically drive the inner binary to high...
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Martin Urbanec (Silesian University in Opava)Poster
In this talk we report on our recent calculation of the measurements of mass and radius of the neutron star in low-mass X-ray binary 4U1608-52. We combine our measurements based on modelling of kHz quasi-periodic oscillations using cusp-torus model and constraints from modelling of X-ray bursts by other authors. We show that kHz QPOs depend strongly on the mass of the source which combines...
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Isabella Mariani (Istituto Nazionale di Astrofisica (INAF))Poster
Jets from accreting black-hole X-ray binary systems (BH-XRBs) are powerful outflows that release a large fraction of the accretion energy and power to the surrounding environment, providing a feedback mechanism that may alter the properties of the interstellar medium (ISM). Studying accretion processes alongside their feedback on the environment is crucial, as it enables the estimate of the...
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Sara Navarro Umpiérrez (Instituto de Astrofísica de Canarias)Poster
One of the main challenges in understanding stellar-mass black holes is the lack of observational data, since most Galactic black holes have been detected through X-ray outbursts and therefore represent a small and biased sample. To overcome this limitation and accelerate the rate of black hole discovery, the HAWKs project was designed, with Mini-HAWKs serving as its pathfinder.
Mini-HAWKs...
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Mr Simo van de Vosse (University of Amsterdam)Poster
Type-I X-ray bursts in neutron star (NS) low mass X-ray binaries are highly energetic events with the power to dynamically change the accretion flow. Studying such dynamical effects is a powerful new method that could shed light on accretion disk physics, coronae and the origin of relativistic jets. Correctly modelling time resolved X-ray spectra during these bursts allows for measurements of...
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Prof. Diego Altamirano (University of Southampton)Poster
Accreting black holes and neutron stars exhibit rapid X-ray variability that provides a unique probe of the innermost regions of the accretion flow. Many of the most interesting phenomena, however, occur unpredictably and on timescales that require long, uninterrupted observations, making them difficult to study with current and planned observatories.
We present NEBULA-Xplorer, a Mini-Fast...
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Mr Chun Hei Chan (Department of Physics, National Cheng Kung University)Poster
Transitional millisecond pulsars (tMSPs) are rare neutron-star binaries that switch between accretion-powered and rotation-powered states, offering a valuable laboratory for studying the coupling between accretion flows, magnetospheres, and pulsar winds. Their simultaneous optical and X-ray variability often shows complex correlated or anti-correlated behavior, but the physical origin and...
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Kevin Alabarta (INAF-OAB)Poster
How stellar-mass black holes distribute accretion power between the disc, corona and jet, and how this balance evolves throughout an outburst, is central to understanding accretion and ejection in X-ray binaries. MAXI J1348$-$630 is a black-hole X-ray transient that underwent a bright 2019 outburst followed by a reflare and several lower-luminosity mini-outbursts. Its dense radio, optical and...
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Mokhine Motsoaledi (New York University Abu Dhabi)Poster
V4641 Sgr is a peculiar black hole X-ray binary with unusual X-ray outburst behaviour, and bright superluminal radio jets which are misaligned with the very high-energy and ultrahigh-energy gamma ray emission. This system may be considered as a low mass X-ray binary due to mass transfer via Roche lobe overflow, despite harbouring a B-type subgiant companion star, which provides a rare...
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Carlo Ferrigno (Istituto Nazionale di Astrofisica (INAF))Poster
Accreting neutron stars in high-mass X-ray binaries are endowed by a strong magnetic field that has a major impact on their electromagnetic signal. Modulated by orbital motion and stellar rotation, the light curve is variable on different time scales from millisecond to years. The signal is also dramatically different as function of the photon energy. While the phenomenology is known in broad...
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Rene Sprna (SLU - Institute of Physics in Opava)Poster
We present Monte Carlo calculations of accretion disk illumination by a neutron star spreading layer and derive the corresponding radial profiles of Fe-K photoionizing flux. In contrast to the phenomenological emissivity prescriptions commonly used when fitting reflection spectra, our model is directly tied to the physical geometry of the illuminating area on the stelar surface. We show that...
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Asaf Pe'er (Bar Ilan University)Poster
Radiative cooling can strongly influence the structure and dynamics of black hole accretion disks. Considering synchrotron and bremsstrahlung emission, we quantify how radiative losses modify the disk structure and the accretion dynamics. We introduce a critical value of the mass accretion rate, ~10^{-5.5} Eddington, above which the cooling by the synchrotron process efficiently radiates the...
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Yijia ZhangPoster
Radio surveys of ultraluminous X-ray sources (ULXs) allow us to find supercritically accreting compact objects (SS 433/W50 like systems) or stripped nuclear black holes in nearby galaxies. We identified 21 such objects by crossmatching a ULX catalog with the Rapid ASKAP Continuum Survey (RACS) and Very Large Array Sky Survey (VLASS). They may have a diverse population.
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(i) Three have a... -
Justine Crook-Mansour (University of Oxford)Poster
A0538–66 is a neutron-star (NS) Be/X-ray binary in the Large Magellanic Cloud, and is one of the most unusual accreting compact objects known, exhibiting rare episodes of super-Eddington accretion, rapid optical and X-ray flaring, and an exceptionally short spin period that likely makes it the fastest-spinning accretion-powered NS in a high-mass X-ray binary. The origin of its recently...
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Bei You (Wuhan University)Talk
The X-ray-emitting corona near a black hole (BH) is too small to be directly imaged, but the rapid variability is used to infer the geometry by measuring time lags caused by coronal X-rays reflecting off the disk, known as reverberation lags. Though reverberation lags have previously been detected for some supermassive BHs in active galactic nuclei (AGNs), detecting them from stellar-mass BHs...
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Dr Kelebogile Gasealahwe (UCT, SARAO)Poster
Discovered in 1998, SAX J1808.8-3658 remains the archetypal Accreting millisecond X-ray pulsar (AMXP) (Wijnands & van der Klis 1998). After numerous outbursts since its discovery, recurring every 2 - 4 years, the source entered into a new outburst mid 2025. A day after the outburst was announced by the X-ray Binary New Early Warning System (XB-NEWS), we began observations with the MeerKAT...
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Dr Seshadri Majumder (Graduate School of Science, Kyoto University)Poster
Quasi-periodic oscillations (QPOs) are coherent X-ray timing features frequently observed in black hole X-ray binaries (BH-XRBs), originating from the innermost region of the accretion disc-corona system where general relativistic effects are expected to be in play. Among the proposed QPO models, the Lense-Thirring (LT) precession of the inner hot flow predicts a systematic modulation of the...
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Gastón Escobar (Instituto de Astrofísica de Canarias)Poster
We present a new method to identify candidate quiescent black holes based on optical variability analysis, using data from Mini-HAWKs — a pilot photometric survey currently underway with the JAST80 telescope at the Observatorio de Javalambre.
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The Mini-HAWKs strategy exploits a known correlation between the full width at half maximum (FWHM) of H-alpha emission lines and the semi-amplitude of... -
Tomáš Stanovský (Silesian University in Opava)Poster
We develop an end-to-end simulation pipeline to evaluate the detectability of high-frequency quasiperiodic oscillations (HFQPOs) in signals from black hole X-ray binaries with various space observatories. Light curves (LC) from analytic (Karas, 1996) and ray traced (Bakala et al., 2007, 2015) hotspot models are combined with the global flux of microquasar GRS 1915+105; and photon events with...
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Abhisek Tamang (Indian Institute of Science, Bengaluru & Raman Research Institute, Bengaluru)Poster
Her X-1 is an intermediate (or low) mass X-ray binary pulsar that exhibits a ~35-day super-orbital modulation whose origin-disc precession or neutron-star free precession-remains debated. Earlier work reported stochastic variations without a clear long-term trend. Using $\sim$50 years of data from CGRO/BATSE, RXTE/ASM, Swift/BAT, Fermi/GBM, and MAXI/GSC supplemented with archival measurements,...
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Jiří HorákPoster
Low-frequency quasi-periodic oscillations (LF QPOs) in neutron star (NS) X-ray binaries are commonly interpreted as manifestations of Lense–Thirring (LT) precession of the inner accretion flow. We utilise the Hartle–Thorne spacetimes to test this hypothesis, employing test particle motion as well as models of geometrically thick accretion tori. Our focus is on the atoll source 4U 1608–52, for...
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Khushi TaoriPoster
Simulations of black hole X-ray binary systems (BHXRBs) can help us understand physical changes in these systems as an outburst occurs. Here, we present the first three-dimensional GRMHD simulations of created using the H-AMR code of a low mass X-ray binary undergoing a spectral state transition, both in the MAD (magnetically arrested disk) and SANE (standard and normal evolution) models....
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haifan zhuPoster
We analyzed NICER observations of the 2025 outburst of the black hole X-ray binary 4U~1630$-$47 to investigate the spectral--timing properties of its transient low-frequency quasi-periodic oscillations (QPOs) and mHz quasi-regular modulation (QRM). During the rising phase of the outburst, the QPO centroid frequency increased from $\sim 0.24$ Hz to $\sim 3.43$ Hz. Wavelet-based state separation...
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Abhisek Tamang (Indian Institute of Science, Bengaluru & Raman Research Institute, Bengaluru)Poster
Vela X-1 is an archetypal high-mass X-ray binary pulsar in which strong X-ray irradiation from the neutron star significantly affects the companion’s stellar wind. A smooth, isotropic wind cannot explain the observed variability in the system, especially the orbital variation in the absorption column density along the sight line, suggesting the presence of additional structures such as...
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Barbora Bílá (Silesian University in Opava)Poster
Relativistic accreting stars often exhibit strong quasi-periodic oscillations in their radiation. In our study, we examined the modulation of X-ray radiation from the neutron star boundary layer through the obscuration of an oscillating, thick inner accretion flow (Torok et al., ApJ, 2025). To do this, we adopted the full relativistic ray-tracing code LSD of Bakala et al. (A&A, 2015). We found...
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