Most of the baryonic matter in the universe, which exists primarily as intergalactic hydrogen, was ionized by the far-UV radiation of early galaxies during the Epoch of Reionization (EoR). However, many of these faint galaxies remain undetectable by traditional surveys. Line intensity mapping (LIM) addresses this limitation by measuring the integrated emission from entire galaxy populations. By post-processing the IllustrisTNG300 simulation, we produced mock [CII] line observations tailored to the specifications of the upcoming Fred Young Submillimeter Telescope (FYST).

Our forecasts suggest that detecting [CII] line emission up to z ≈ 6.5 is feasible. A significant challenge, however, is the contamination from CO lines emitted by lower-redshift galaxies, which overlap in observational frequency with high-redshift [CII]. To address this challenge, we modeled the CO foreground and applied a masking technique to mitigate its impact. While [CII] line emission likely dominates at redshifts below 5, extensive masking is required to recover the [CII] signal around z ≈ 6, and more advanced foreground separation methods will be needed to probe redshifts beyond 6. This ongoing work will help unlock the full potential of FYST to trace galaxy evolution during and immediately after the EoR using the LIM technique.
(Cologne)

Blazars, among the most powerful radio beacons in the universe, host relativistic jets launched from the vicinity of the black hole–accretion disk system at the cores of active galactic nuclei (AGN). When these jets are closely aligned with the Earth’s line of sight, the AGN are classified as blazars. Due to the relativistic motion of the jet plasma, their radio emission is significantly boosted, making blazars prime targets for high-resolution radio interferometric observations with the Very Long Baseline Array (VLBA), Global Millimeter VLBI Array (GMVA), and Event Horizon Telescope (EHT).  

The MOJAVE program has been monitoring blazars at 15~GHz with the VLBA for over two decades. In this talk, I will present studies of jet structure, dynamics, and polarization properties based on data from the VLBA, GMVA, and EHT. Sub-milliarcsecond-resolution images at 15 GHz of selected blazars allow for the investigation of relativistic transverse waves, as well as the fine structure and kinematics of both quasi-stationary and moving jet components on sub-parsec scales. I will discuss the association of blazars with sources emitting in the X-ray and gamma-ray regimes, as well as very high-energy sources, along with jet models and particle acceleration mechanisms.
(Cologne, Host Volker Ossenkopf-Okada)

The interstellar medium provides an enormous laboratory for the exploration of chemistry of various kinds. Some of the most molecule-rich interstellar objects – known as “hot molecular cores” – are accretions of warm gas and dust that surround young protostars, which ultimately evolve into high-mass stellar systems. Along with their low-mass (solar-type) analogs, “hot corinos”, they are characterized by rich rotational emission spectra that exhibit a wealth of organic molecules of varying degrees of complexity. But the formation of these “hot” (>100 K), gas-phase molecules is closely related to an earlier stage of chemistry that occurs on the surfaces of microscopic dust grains at much lower temperatures. Recent observational, experimental and modeling evidence indicates that some of the most complex molecules that we detect in highly evolved protostellar systems may have a much earlier origin than previously thought.

Here I will present new modeling treatments that allow us to trace the continuum of hot and cold chemistry involving interstellar organics. I will also demonstrate some initial results from new coupled radiation hydrodynamics and gas-grain chemical modeling of hot core/corino systems, and our efforts to simulate observations of their molecular line emission.
(MPIfR Bonn, Host Arnaud Belloche)

Precise measurements taken at radio and infrared wavelengths over the last two decades have led to the conclusion that a 4.2 million solar mass black hole lies at the center of the Galaxy.  These measurements are consistent with the predictions of the Einstein’s general theory of relativity. I will present highlights of recent JWST observations to study the flaring activity of the black hole. The variability of the black hole probes the process of the accretion flow at a distance of few Schwarszchild radius. These observations indicate that the flux of Sgr A* is fluctuating constantly with multiple synchrotron flares per day.  I will argue that two distinct populations of particles produce bright and faint synchrotron variable emission.  As for the origin of the infrared flares, a number of recent simulations suggest that flares are ejected plasmoids from the accretion disk due to reconnection of the magnetic field lines. Time permitting, I will also discuss the connection between near-IR, radio/submm and X-ray flux variability in the context of plasmoid ejection.
(Cologne, Host Florian Peißker)

tbd
(Cologne, Host Stefanie Walch-Gassner)

The intricate dynamics of molecular clouds, pivotal to the formation of stars, have been a subject of our ongoing investigation. In the SILCC-Zoom simulation suite, we investigate the formation and evolution of molecular clouds within their galactic, multi-phase ISM environment. The adaptive mesh refinement (AMR) magneto-hydrodynamics simulations include a chemical network and radiative transfer. 

The clouds are divided into coherent and hierarchical substructures using dendrograms. A detailed virial analysis of the identified substructures unravels their energetics. We can show that substructures that mostly consist of atomic, rather than molecular gas, are always unbound. Only denser, molecular structures become “bound”, but often they seem to be stabilized by ram pressure or thermal pressure rather than truly bound by self-gravity. Only a few structures are clearly gravitationally bound. Our results put the role of gravity to the test and have important implications for the low star formation rate and efficiency in molecular clouds.
(Cologne)

Picture Credit: Fig 3 from Ganguly, SW, + 2024, MNRAS, 528, 3630ff.