Special Colloquium
Prof. Tom Megeath	SCHEDULED

University of Toledo, Ohio

I will present a study of jets and winds from protostars across the mass spectrum with JWST. These data show collimated jets and wide angle winds from five protostars with masses from 0.12 to 12 solar masses. I will describe our efforts to disentangle the jets from the massive protostar I20126 from those of its companions, and the detection of the jet from the massive protostar in ionic species. I will then overview current results from the HEFE, a 190 hour large program on JWST. Here we show star formation in the filamentary OMC2/3 region of Orion, likely the most active region of ongoing star formation in the nearest 500 pc. Using NIRCam multiband imaging of the entire region and IFU imaging of 13 Class 0 protostars, these provide a detailed picture of feedback from outflows in this filamentary environment. I will focus on HOPS 383, a protostar that recently underwent a 15 year outburst, and our efforts to find a counterpart to the outburst in the jet from this protostar.

	Special Colloquium
Dr. Frederic Jaron	SCHEDULED

TU Vienna

The geodetic and astrometric application of VLBI is a powerful technique for the realization of global reference frames and the measurement of Earth orientation parameters. Source structure is one of the remaining unmodeled errors that prevent the technique from reaching its ultimate accuracy goals. We have developed a method to remove the influence of source structure from the output of the DiFX software correlator that fits into the common geodetic processing pipeline. In this talk I will present our approach and its application to observational data of the VLBI Global Observing System (VGOS). Improvement of closure group delays and post-fit residuals is obtained for selected sources when reliable image information is available.

	Special Colloquium
Dr. Christian Fendt	SCHEDULED

MPIA Heidelberg

I will show resent results of connecting relativistic MHD simulations of pc-scale AGN jets to mock emission maps applying a subgrid model of diffusive shock acceleration of highly relativistic particle and subsequent synchrotron cooling. Due to the full 3D data cube and full time resolution we can derive emission maps for different viewing angles, as well as variability studies for the jet spectrum and jet variability. We can further follow the motion of radiation patterns, and find that these follow the shock motion rather than the jet fluid velocity. These jet knots thus identify different shock structures in the jet, also indicating different particle populations, each defined by the age and motion of the respective shocks.

	Special Colloquium
Prof. Shrinivas Kulkarni	SCHEDULED

California Institute of Technology, Pasadena, USA

What unites the following: high velocity clouds crashing into the Galactic disk, wide and/or ultra-deep narrow band imaging by amateur astrographers, state-of-the-art IFUs with considerable grasp (MUSE, Keck Cosmic Imager, the Local Volume Mapper), bow shocks of various types, zombie nebulae and ionized cometary nebulae. The common factor is sizzling discoveries. Attend this seminar to learn more!

	Main Colloquium
Professor Ziggy Pleunis	SCHEDULED

University of Amsterdam

Fast radio bursts (FRBs) are one of the most exciting mysteries in contemporary astrophysics. They last only a fraction of a second but are bright enough to be detectable from halfway across the Universe. FRBs are unique astrophysical tools: they are perfect point sources, impulsive, and being in the radio band they are also distorted in ways that carry valuable information about otherwise invisible matter, which makes them unprecedented probes of the local environments of compact objects and the structure and magnetization of the interstellar and intergalactic media. FRBs will be even more useful when we better understand their sources and emission. A small fraction of FRBs has been observed to repeat, which has ruled out a cataclysmic origin for these sources and allows for detailed multi-wavelength follow-up observations that constrain FRB models. It is as-yet unclear whether all FRBs repeat and if FRB models based on a few well-studied repeaters can be extrapolated to the full population. Canada's CHIME telescope has been instrumental in uncovering the diversity of FRBs: it provided the first large statistical sample of FRBs, and it is continuing to lead the discovery of repeating sources by revisiting the Northern sky every day. At the same time, we have opened a new window into studying these sources by detecting the lowest-frequency FRBs with the LOFAR telescope. I will argue that the next revolution in FRB science is imminent through the collection of the first large sample of FRBs with known redshifts through the CHIME/FRB "Outriggers" upgrade. Complemented by observations from LOFAR 2.0 and other facilities, this promises to solve the mystery of FRBs and will uniquely address a variety of unsolved problems in astrophysics, such as the detection of the "missing" baryons and the impact of feedback on the formation of galaxy haloes.

	Main Colloquium
Prof. John McKean	SCHEDULED

Kapteyn Astronomical Institute, University of Groningen & ASTRON, Dwingeloo, The Netherlands

Gravitational lensing provides a powerful probe of the global mass properties of galaxies, which are best tested using observations at extremely high angular resolution. In addition, through detailed observations of the lensed images, it is possible to place tight constraints on the nature of dark matter through measuring the abundance and properties of low mass haloes via their subtle gravitational lensing signal. Here, we first present new observations with the VLA and HSA to better understand the source of so-called flux-ratio anomalies in four image gravitational lenses, which historically provided the first constraints on CDM using lensing studies. Next, we will present the analysis of the mass properties of ten massive elliptical galaxies at intermediate redshifts, by combining gravitational lensing and the sensitivity and resolving power of the Atacama Large Millimetre Array (ALMA) and global Very Long Baseline Interferometry (radio VLBI). Using imaging at 25 to a few milli-arcsecond resolution, we find that complex mass models with angular structure are strongly favoured by the data. In addition, such observations are sensitive to small-scale structure either in the lens or along the line-of-sight to the background source. From such an analysis of the data from global VLBI observations, we detect of a low mass (million solar mass) dark object, whose properties are inconsistent with a dark matter halo from either cold or warm dark matter models, but may be in agreement with more exotic models, like self-interacting dark matter. Finally, we present a brief overview of future studies using the SKA and a likely African VLBI facility that includes the SKAMPI, MPG-DZA and AMT dishes. Throughout we will also provide some asides on the pc-scale structure of radio jets, constraints on galactic-scale magnetic fields and electron densities, and the super-resolved (about 10 to 20 pc-scale) properties of starburst galaxies at redshifts 1 to 4.

	Special Colloquium
Niloofar Pourjafari	SCHEDULED

University of Calgary

Magnetic fields are an important component of the interstellar medium, influencing the transport of cosmic rays and the interaction between galactic disks and halos. NGC 891, one of the closest Milky Way analogues, provides an excellent opportunity to study these processes in an edge-on system. In this talk, I will present new VLA S-band polarization observations of NGC 891 combined with existing C-band data from the CHANG-ES survey. We detect a large-scale polarized halo and find evidence for an ordered magnetic field extending across the galaxy. The observations suggest that much of the observed polarized emission originates on the near side of the galaxy, providing a new perspective on the magnetized halo of this highly inclined system. We also identify localized polarized structures on kiloparsec scales in the north-eastern halo that coincide with diffuse X-ray and Hα emission. These features likely trace magnetic fields associated with recent star formation activity and feedback, possibly including a superbubble powered by clustered supernovae. Together, these observations reveal both the global magnetic field structure of NGC 891 and the influence of local star formation activity on its halo.

	Main Colloquium
Dr. T. Joseph W. Lazio	SCHEDULED

University of Michigan

SunRISE is a constellation of six identical small spacecraft (6U CubeSats) that will form a space-based VLBI array. Each spacecraft carries a decametric-hectometric (DH, 0.1 MHz to 25 MHz) receiving system paired with global navigation satellite system (GNSS) receivers. The Solar DH receivers will be used to record signals from Type II and Type III solar radio bursts while the GNSS receivers will time stamp the data and enable the determination of the spacecraft locations for subsequent ground-based cross-correlation. SunRISE will reveal aspects of how solar energetic particles (SEPs) are accelerated at coronal mass ejections (CMEs) by tracking Type II bursts and how SEPs are released into interplanetary space from the Type III bursts. The six spacecraft that form the SunRISE interferometer will fly in a passive formation in a supersynchronous geosynchronous Earth orbit (super-GEO). The nominal baseline will be 10 km, obtaining an angular resolution of approximately 10' at 10 MHz. I describe the implementation of SunRISE, illustrating how the combination of on-board and ground operations and processing are required to achieve a fully space-based VLBI array. While SunRISE is a NASA Mission of Opportunity that will conduct science in its own right, it also is intended to be a pathfinder for future space-based radio astronomy missions. I provide an initial assessment of the "experience gained" for future missions, from the perspective of both the SunRISE science and technical implementation.

	Main Colloquium
Dr. Casey Law	SCHEDULED

Caltech, USA

TBD

	Main Colloquium
Professor Ilse de Looze	SCHEDULED

Ghent University

TBD

	Main Colloquium
Prof. Sirio Belli	SCHEDULED

University of Bologna

TBD

	Main Colloquium
Prof. Dr. Felix Aharonian	SCHEDULED

DIAS/Dublin and MPIK/Heidelberg

PeVatrons - cosmic-ray factories capable of accelerating particles to petaelectronvolt (PeV) energies - are widely believed to play a key role in resolving the century-old mystery of the origin of Galactic cosmic rays. For decades, the nature of these objects has been the subject of extensive theoretical and observational studies, with supernova remnants long regarded as the prime candidates. In recent years, major observational advances, primarily the detection of gamma rays with energies exceeding 100 TeV from dozens of Galactic sources, have led to a breakthrough with far-reaching implications. Taken together, these developments suggest that the Milky Way hosts a diverse population of extreme particle accelerators capable of producing cosmic rays at PeV energies. At the same time, increasingly precise measurements of cosmic-ray spectra and composition have significantly improved our understanding of Galactic cosmic rays from GeV to PeV energies. These observations reveal that a diversity of cosmic-ray accelerators associated with several Galactic source populations, including supernova remnants, star-forming regions, pulsar wind nebulae, and microquasars, may create, despite their fundamentally different physical environments, near-ideal conditions for particle acceleration operating close to the theoretical limits. This review summarizes the theoretical predictions, observational discoveries, and current interpretations of PeVatrons, discusses their implications for high-energy astrophysics, particularly for the origin of Galactic cosmic rays, and outlines future directions for multiwavelength observations.

	Main Colloquium
Dr. Joop Schaye	SCHEDULED

Leiden University, The Netherlands

TBD

	Special Colloquium
Dr Minghui Xu	SCHEDULED

GFZ Potsdam

TBD

	Main Colloquium
Dr. Silvia Spezzano	SCHEDULED

MPE

TBD

	Main Colloquium
Dr. Kathryn Kreckel	SCHEDULED

Astronomisches Rechen-Institut, Universität Heidelberg, Germany

TBD