Science Meeting: Bridging the environment gap and the spatial scale gap III

28.10.2026, 10am – 5pm
Old Workshop, I. Physics Institute, Cologne

11:45	Prachi Misra	Rotational spectroscopic study of Oxetanones for astronomical search	Old work-shop	Rotational spectroscopy continues to play a central role in laboratory astrophysics, providing the high-precision spectroscopic data required for the identification of complex organic molecules in the interstellar medium. To date, more than 350 molecular species have been detected in space, including oxygen-bearing heterocycles such as oxirane (c-C2H4O) and methyloxirane (C3H6O). Within the C3H4O2 isomeric family, 3-hydroxypropenal has been detected towards the solar-type protostar IRAS 16293–2422 B, highlighting the astrochemical relevance of related cyclic isomers. In this contribution, we present a detailed rotational spectroscopic study of the C3H4O2 isomers, specifically 2-oxetanone and 3-oxetanone. Rotational spectra were recorded up to 500 GHz with home-built spectrometers based on complementary techniques: conventional absorption spectroscopy and chirped-pulse Fourier-transform microwave spectroscopy. Comprehensive spectral assignments enabled the determination of accurate ground-state rotational and centrifugal distortion constants, together with the characterisation of several low-lying vibrationally excited states. The resulting spectroscopic parameters substantially refine previous datasetsets and provide reliable frequency predictions throughout the millimeter and submillimeter ranges. These data established a robust foundation for astronomical searches of the oxetanone isomers.
12:05	Sam Marlton	Searching for new interstellar molecular ions in the infrared and visible range	Old work-shop	Astronomers and spectroscopists have had impressive success in detecting hundreds of gas-phase molecules in the interstellar medium. Many of these molecules have been detected in the infrared,  and a few have been detected in the visible range. Because the vast majority of the detected astro-molecules have come by measuring the rotational transitions of molecules in the laboratory, and detecting these transitions in astronomical spectra, the landscape of detected interstellar molecules  is biased towards light molecules with large dipoles. Therefore, efforts to detect new interstellar molecules using optical and infrared spectra, are valuable for revealing blind spots in the astrochemical inventory. This talk discusses new experimental strategies and recent attempts to detect new molecular ions by their infrared or visible transitions. The novel experimental method employed is leak-out spectroscopy, (LOS) which affords high-resolution measurement of photostable ions that could not be measured by previous techniques. The results from infrared LOS for small cations (such as CH2+ and C2H4+) are compared with astronomical data from the NASA infrared telescope and JWST, and results from visible LOS are compared with databases of diffuse interstellar bands.
12:25	Beth Jones, Tatiana Rodriguez, Peter Schilke	Into the Dusty Protostellar Cores: Recovering properties below 1000au scales	Old work-shop	Determining the properties of deeply embedded, dense cores hosting and feeding individual or multiple systems of high-mass protostars is crucial to understand the conversion of a galaxy’s molecular gas into a stellar population. The strong density gradients combined with the high densities (up to n(H) ~ 10^10 per cm cubed) result in strong opacity effects in even complex molecules, limiting the ability to reliably recover their properties. The ALMA Large Program ALMAGAL has observed over 1000 high-mass star forming clumps and unveiled the many ~1000 au protostellar cores embedded within. However, obtaining reliable core masses from their measured continuum fluxes is limited by the uncertainty on the core temperatures,   and their true luminosities remain inaccessible. To calibrate the relationship between observed CH3CN rotational temperatures and the mass-averaged temperature required to derive reliable protostellar core masses, we have fitted the spectral line temperature in 10,000 synthetic protostellar core observations. Fitting to observed vibrational states of molecules, meanwhile, can be used to determine the true luminosity by tomography. Here, we present the results from this fitting and analysis, and the applicability and similarity to the 1300 cores detected in CH3CN in ALMAGAL and for a select subsample, their measured true luminosities.
12:40	Lunchbreak
13:40	Furkan Dincer, Susanne Pfalzner	The role of massive stars in the cluster expansion phase	Old work-shop	Most stars form in clusters that undergo substantial dynamical evolution during their first few million years. Massive stars play an important role in shaping this evolution through their gravitational interactions and stellar evolution. However, even clusters with similar total stellar masses can contain substantially different massive-star populations as a consequence of stochastic sampling of the initial mass function (IMF). We investigate how these stochastic variations influence the early dynamical evolution of young star clusters. Using ensembles of direct N-body simulations with 500–10,000 stars, we follow cluster evolution over 10 Myr. We model the effects of rapid residual gas removal, and compare models neglecting stellar evolution with those including it. We find that the initial massive-star (M* > M☉) content has a particularly strong influence on the evolution of low-mass clusters (N = 500). Clusters with overabundance of massive stars tend to exhibit smaller half-mass radii, higher expansion velocities, and larger unbound fractions. These trends become substantially weaker in richer clusters and are modified by stellar evolution. Our results demonstrate that stochastic variations in massive-star populations can produce considerable differences in early cluster evolution, even among clusters formed under otherwise similar initial conditions.
14:00	Agata Karska	[C I] as a tracer of star formation across spatial scales: from clumps in the Milky Way to clouds in the nearby galaxies	Old work-shop	Emission lines of [C II], [C I], and CO in molecular clouds are among the most important diagnostic probes of star formation. In the most shielded, dense clumps, carbon is mostly locked in CO, and [C I] and [C II] emission originates in relatively narrow layers exposed to UV radiation. In low-metallicity environments, however, the dust abundances are lower and the shielding is less efficient. As a result, [C I] is expected to become a more important reservoir of carbon and a possible tracer of molecular gas not seen in CO. In the Milky Way, the amount of such “CO-dark gas” has been shown to increase as a function of Galactocentric distance, providing a path to study the CO/C/C+ transition as a function of metallicity. In this talk, I will summarize recent observational results concerning [C I] emission on scales of individual star-forming clumps in the inner and outer Galaxy as compared to the molecular clouds in the nearby galaxies (LMC, M33). In particular, I will discuss the gradients of [C I] / CO as a function of metallicity and the relative distribution of [C I] and CO emission in spatially-resolved regions. I will wrap up with the on-going preparations for CCAT/CHAI early science focused on [C I] observations in the outer Galaxy and LMC.
14:20	F. Peissker, C. Nagar, E. Bordier, L. Labadie	The multifaceted view of RCW108	Old work-shop	RCW108 is an active star-forming molecular cloud complex and H II region which has been explored in its cold dust and molecular content, as well as in its cluster properties via the stellar mass distribution and the multiplicity status. This multi-wavelength, multi-scale approach reveals an environment possibly prone to feedback-triggered star formation at the sub-parsec scale, characterized by single-peaked stellar density and flatter mass-function, and a higher multiplicity fraction for separation <2000au compared to older clusters. RCW108 is an interesting habitat candidate to attempt bridging different spatial scales from hundreds of AUs to sub-pc scales.
14:40	Han-Tsung Lee, Peter Schilke, Gary Fuller, Alvaro Sanchez-Monge, Beth Jones, Tatiana Rodriguez	Characterizing temperature structures of massive star-forming clumps in ALMAGAL survey	Old work-shop	The presence of massive stars is expected to have a significant impact on the surrounding environment. Feedback from high-mass (proto)stars plays an important role on affecting the subsequent star formation by creating thermal structures in their natal clouds. ALMAGAL, an ALMA large program observing >1000 massive clumps in the Galaxy provides unprecedented opportunities to study this aspect in star formation process. We derive rotational temperature maps for 419 clumps through excitation analysis using H2CO line data around 218 GHz with a resolution of ~1.3” (~4000 au). We found temperatures (25->200 K) from H2CO are generally higher than dust temperatures calculated from FIR observations (~10-30 K), but lower than those derived from CH3CN (~a few 100 K). The measured thermal energies of the clumps range from 10^43 to 10^49 ergs and show a correlation with clump luminosity-to-mass ratios, indicating feedback becomes more significant as clumps evolve. Radiation and outflow feedback appear to be overall equipartitioned based on the comparison between energies produced by radiative and mechanical outflow heating. We also found a tentative increasing trend between the number of cores and the thermal energies of the clumps, which may be the result of mechanical (outflow) feedback promoting fragmentation.
14:55	Akash Gupta	Tracing the Chemical Evolution of High-Mass Star-Forming Regions: From pre-stellar cores to hot cores	Old work-shop	In this talk, I will present time-dependent synthetic spectra tracing the evolution of HMSFRs from their pre-stellar cold core phase to the hot core stage. We achieve this by coupling high-resolution (maximum resolution of 50 au) hydrodynamical simulations with the state-of-the-art astrochemical code Nautilus, utilizing a comprehensive network of approximately 1,000 species and 13,000 reactions. While traditional hot core chemical models are dynamically static—accounting primarily for changing temperatures—our model actively incorporates mass transport. By utilizing Lagrangian tracer particles that follow the gas during cloud collapse, we account for the continuous delivery of material with diverse chemical histories from the outer envelope to the inner hot regions. Furthermore, we evaluate how varying initial molecular cloud conditions impact the chemistry during and after the collapse phase. Our results demonstrate that the “chemical memory” of these initial conditions persists throughout the collapse and strongly influences the hot core phase. To bridge our theoretical framework directly with observations, we process our 3D chemical distributions through the RADMC-3D radiative transfer code to generate synthetic spectra for various gas-phase molecular lines, specifically targeting the frequency ranges of the ALMAGAL Large Program. This end-to-end approach—combining 3D hydrodynamical simulations with complex chemistry and radiative transfer—yields detailed, time-dependent synthetic observations for HMSFRs. By comparing our synthetic spectra directly with ALMA data, we can disentangle diverse physical conditions and provide significantly stronger constraints on the chemical and dynamical history of massive star formation.
15:10	Coffee Break & Poster

Science Meeting: Bridging the environment gap and the spatial scale gap II

28.01.2026, 9am – 4pm
Old Workshop, I. Physics Institute, Cologne

9:00 – 9:10	Welcome & Introduction	Stefanie Walch-Gassner
9:15 – 9:30	A cloud-scale and multi-phase and view of the star formation quenching process	Dario Colombo
9:30 – 9:45	Non-equilibrium-ionisation models for nebulae around massive stars, and predicted line emission	Jonathan Mackey
9:45 – 10:00	The lifetime of 100,000 molecular clouds in the nearby Universe.	Zein Bazzi
10:00 – 10:15	Spiral Arm-Driven Velocity Dispersion in the Warm Neutral Medium	Wajdee Chayeb
10:15 – 10:30	BREAK
10:30 – 10:45	CO-HCN-SFR variations across spiral arms in NGC 4321 and M51	Minou Greve
10:45 – 11:00	A second hot core in the outer Galaxy: impact of metallicity on the formation of complex organic molecules	Youxin Wang
11:00 – 11:15	The Extent of AGN Feedback on the ISM	Mallory Thorp
11:00 – 12:00	Discussion Round
12:00 – 13:00	BREAK
13:00 – 14:30	Postersession & Discussion
14:30 – 15:30	SFB1601/II Proposal Discussion Round	Arshia Jacob
Posters
1		Teo Topkaras
2	High-Resolution Molecular Line Mapping in M51 and Milky Way	Ina Galic, Mallory Thorp
3	Modeling OH masers in G034.256+0.145	Ying-Chi Hu
4	WCCC vs. HC Chemistry: Spatial Distribution of Deuterated Species in Protostars	Morgan Owen

Registration is mandatory!

Machine Learning & Astrophysics — 21 November 2025

Contributed Talks

Speaker	Title
Andreas Lintermann	Integration of AI in Physics Simulations
Aleksander Bojchevsky	Trusting the Untrustworthy: Toward Reliable AI for Science
Stefan Kesselheim	Simulations, surrogates, statistics: Machine Learning in Astrophysics and beyond

Poster Contributions

Contributors (Pitch, Poster)	Collaborators	Pitch Title
Devika Bhatnagar	V. Balakrishnan, V. Venkatraman Krishnan, P. Freire, M. Kramer	The Pulsar Sorting Hat: AI to Accelerate Discoveries of Relativistic Binaries
André Bresges		Functional Magnetic Resonance Imaging of Human Brain Functions during simulated car driving: Possible applications for a Shared Universe Engine
Tobias Solymosi	T. Danowski, B. Jones, S. Kesselheim, P. Schilke	Prostellar structure recovery using deep learning
Jakob Dietl	J. Dietl, F. Pacaud, T. H. Reiprich, A. Rüttgers, Z. Lähner, A. Veronica	Uncovering the Giants in the Sky – Semantic Segmentation of Galaxy Clusters in Astrophysical Surveys
Lucie Flek	C. D. Le, D. Kaczér, K. Schmieden, M. Schott	Analyzing Gravitational Waves with Transformers
Aleyna Nuray Ortakoese	M. Weis, S. Walch-Gassner	Following Tracer Particles to Identify Filaments in Star-Forming Cores with HDBSCAN
Daniel Seifried	R. Patel, S. Walch	The filamentary ISM: Structure Identification and characterization

Science Meeting: Bridging the environment gap and the spatial scale gap I

09.10.2025, 9am – 5pm
seminar room 0.03, ETP, Physics Institutes, Cologne

Registration is closed (mandatory!)

9:00 – 9:10	Welcome & Introduction	Stefanie Walch-Gassner
9:10 – 9:35	What We Talk About When We Talk About Environments	Dario Colombo
9:35 – 9:50	Mapping the cold ISM with JWST: Molecular clouds across galactic environments in 66 nearby galaxies.	Zein Bazzi
9:50 – 10:05	Scale and environment gaps in galaxy formation models	Cristiano Porciani
10:05 – 10:20	Clocking the feedback time: Cross-correlation between star cluster and molecular gas distribution	Hao He
10:20 – 10:30	BREAK
10:30 – 10:45	High-Resolution Molecular Line Mapping in M51 Using NOEMA SWAN	Ina Galic
10:45 – 11:00	Probing Multiplicity in Young and Embedded Massive Galactic Star Clusters with NACO/VLT	Chinmaya Nagar
11:00 – 11:15	Signatures of a hub-filament system located in the Ara constellation – triggered star formation in RCW108	Lucas Labadie / Florian Peißker
11:15 – 11:30	A galaxy protocluster* in our cosmic neighborhood	Nikolaus Sulzenauer
11:30 – 11:45	Tracing Turbulent Gas Excitation in Dust-obscured Galaxies Across Cosmic Time	Prachi Prajapati
11:45 – 12:30	Discussion Round
12:30 – 13:30	BREAK
13:30 – 15:00	Postersession & Discussion	old workshop

Daniel Seifried	TBD
Anaïs Pauchet	Incorporation of proto-stellar disk model in 3D MHD simulations of dense core collapse: emphasis on binary formation and its effects
Leonard Kaiser, Daniel Seifried, Tim-Eric Rathjen, Vittoria Brugaletta, Stefanie Walch	Faraday rotation and magnetic field coherence: The impact of ISM properties
Aaron Beyer, Nikolaus Sulzenauer	Star-formation at the Eddington limit in HerS-1
Aditi Sinha	3D modelling of Clumpy ensembles in Photon-dominated regions(PDRs)
Clarissa Immisch, Lennart Buhlmann, Stefanie Walch-Gassner, Nikolaus Sulzenauer	[CII] Subgrid Model for High-Redshift Galaxies Based on Local ISM Simulations
Jonathan Mackey	Radio observations of stellar bow-shocks with the VLA and Effelsberg Telescopes

Science Meeting: comparison of observations and simulations

08.07.2025, 10am – 3.30pm

To get to the old workshop, enter the Physics Institutes of the UoC, then turn into the staircase in front of the PH1. Go one floor down and go through the glass door, the old workshop is straight ahead.

Preliminary Program

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