Conveners
Parallel session: Extreme Astrophysics / Compact Objects
- nathalie degenaar (university of amsterdam)
Parallel session: Extreme Astrophysics / Compact Objects
- Archisman Ghosh (Ghent University)
Parallel session: Stars and Planets
- Carsten Dominik
ASTRON and S&T corporation are developing a detector of extreme solar radio bursts (SRBs). The aim is to provide real-time alerts and radio spectra from 3-3000MHz to KNMI and the Dutch military, so they can warn the Dutch vital economic sectors, as well as radio and radar operators of current radio interference due to the Sun. 70% of the first two phases of instrument development has been...
In 2019 the Event Horizon Telescope (EHT) delivered the first image of a black hole shadow in the center of the giant elliptical galaxy M87 and is expected to also produce high-resolution images of the supermassive black hole at the center of our Galaxy, Sgr A*. The latter is more challenging to image, being a short time-scale variable source and affected by the interstellar scattering. An...
The detection of the faint 21-cm signal from the Epoch Reionisation (EoR) has been challenging due to strong foregrounds, ionospheric effects and radio frequency interference (RFI) etc. The precise calibration of data has been a key to the detection. Low frequency array (LOFAR) is a radio interferometer which is designed to detect the EoR. Over the years, the LOFAR-EoR team has been working on...
The Auger Engineering Radio Array (AERA) is an array of 153 radio antennas spanning an area of 17 km^2, currently the largest of its kind, that probes the nature of ultra-high energy cosmic rays at energies around the transition from galactic to extra-galactic origin. It measures the MHz radio emission of extensive air showers produced by cosmic rays hitting our atmosphere. The elemental...
CSS100217 was a nuclear flare in a Seyfert 1 galaxy, whose initial interpretation as a nuclear supernova is now debated between a tidal disruption event (TDE) and a flare from the active galactic nucleus (AGN). We discuss new evidence in favour of a TDE interpretation, mainly the marked difference in the optical quiescent flux before and after the outburst, as the post-outburst flux level is...
Accreting black holes emit highly collimated radio jets expanding at speeds approaching light speed. Some of these jets appear to be expanding at superluminal speeds due to geometric effects. While magnetic fields are thought to be responsible for collimating the ejecta, the mechanism that accelerates the material in these jets remains unexplained. For the galactic black hole GRS 1915+105 with...
The origin of most high-energy neutrinos is unknown. They have thus far been observed in coincidence with time-variable emission from three different types of accreting black holes: a gamma-ray flare from a blazar, an optical transient following a stellar tidal disruption, and an optical outburst from an active galactic nucleus. I propose a unified explanation for the latter two of these...
The isolated formation channel is one of the most studied formation scenarios for stellar mass black hole binary (BBH) mergers detected by LIGO and Virgo. Focusing on the effects of uncertain stellar and binary physics, we investigate this BBH formation channel using the rapid binary population synthesis code SeBa. Regardless of our assumptions, the two must common formation path within the...
In the Unification Theory of AGNs the concept of “the torus” plays a crucial role to discern between Type-1 and Type-2 AGNs. Its emission, coming from hot and warm dust peaks at infrared wavelengths, which makes MATISSE an ideal instrument to observe it. The wide spectral coverage of the L, M and N bands, and the high spatial resolution that MATISSE offers, together with its capability to...
The nature and origin of magnetars is a key question across a range of research areas, from fundamental physics to transient astrophysics, where they have been invoked as the engines of a variety of transients including fast radio bursts. It is currently unclear whether magnetars are a common outcome of core-collapse events - only appearing rare due to their short active lifetimes - or if...
The burst energy distributions of repeating fast radio burst (FRB) sources are an important diagnostic of the emission process. To date, burst energy distributions have only been studied for a few active repeaters, and are limited both by telescope sensitivity (for the weakest and most common bursts) and on-sky time (for the brightest and rarest bursts). Though there is evidence for a...
The cool and dusty circumstellar envelopes of asymptotic giant branch (AGB) have for a long time been modelled assuming a spherical symmetry. High spatial resolution observations of these stars have shown that their surroundings exhibit a variety of complex structures. Most of these structures are believed to originate from the interaction of the AGB wind with an obfuscated, nearby, orbiting...
A common method to determine the physical properties of protoplanetary disks is to analyse their spectral energy distributions (SEDs). However, the results are well-known to be degenerate. Running a full Bayesian analysis that can address this problem is challenging due to the high computational cost of full radiative transfer models. In my talk, I will show how we successfully train Neural...
Prominences are cool, dense plasma clouds found in the optically thin solar corona, which makes them classical examples of condensations due to thermal instability. The levitation-condensation mechanism has been used in simulations to explain prominence formation in a flux rope, which is created through shearing and converging motions of coronal loop footpoints. These simulations employ two...
The extreme contrast ratios between stars and their planets at optical wavelengths make it challenging to isolate light reflected by exoplanet atmospheres. Yet, these reflective properties reveal key processes occurring in the atmospheres, and also span wavelengths that include potential O2 biosignatures. High resolution cross-correlation spectroscopy (HRCCS) offers a robust avenue for...
We present a detailed chemical abundance analysis of the YMC NGC 1569-B. The host galaxy, NGC 1569, is a dwarf irregular starburst galaxy located 3.4 Mpc away. We derive abundances of the α, Fe-peak, and heavy elements. Abundance ratios were determined from the analysis of an optical integrated-light spectrum of NGC 1569-B, obtained with the HIRES echelle spectrograph on the Keck I telescope....
Ultra-hot Jupiters have dayside temperatures at which most molecules are thermally dissociated. The dissociation of water vapour results in the production of the hydroxyl radical (OH). We report on the detection of OH in the atmosphere of the ultra-hot Jupiter WASP-76b using high-resolution transmission spectroscopy with CARMENES. Our detection shows that water is indeed being thermally...
