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• 27.11.2026 - Ivelin Georgiev (MPA)
• 20.11.2026 - Louis Mueller (University of Vienna)
• 13.11.2026 - Ryan Leaman (University of Vienna)
• 06.11.2026 - Shaunak Padhyegurjar (University of Vienna)
• 30.10.2026 - Leon Noble (Indian Institute of Technology Indore)
• 23.10.2026 - Institute Assembly
• 16.10.2026 - Luca Fossati (University of Graz) & Benjamin Collins (Universidad de Chile)

  WALTzER and POLLUX: Two Approaches to Exploring the Universe from the UV to the IR

  Luca Fossati (University of Graz)

  I will present the science cases and payload concepts of two conceptually related, though fundamentally different, space instruments with major Austrian contributions: WALTzER and Pollux.

  WALTzER (Wide-band Atmospheric Laboratory for Transiting Exoplanet Research) is a recently submitted ESA F3 mission concept dedicated primarily to the characterisation of exoplanet atmospheres, while also opening new opportunities for Solar System and Galactic astrophysics. The payload uses a single 35-cm telescope feeding a near-ultraviolet spectrograph, a visible spectrograph, and a near-infrared photometer, providing simultaneous near-ultraviolet to near-infrared coverage.

  Pollux is a high-resolution spectrograph, with optional spectropolarimetric capability, working simultaneously from 100 nm to 1.75 microns proposed for the Habitable Worlds Observatory by a European consortium. Pollux will provide an exceptionally broad and detailed view of stars, planets, and their environments. Pollux will also probe the cosmic ecosystem and the baryon cycle across time: from the formation of stars and planets out of gas and dust, through the evolution of galaxies, to the feedback processes that return matter and energy to the interstellar and intergalactic media, including those driven by active galactic nuclei.
  Together, WALTzER and Pollux illustrate how complementary approaches to broad spectroscopic coverage can address science ranging from the atmospheres of nearby planets to the evolution of matter and energy across the Universe.

   

  Tipping the scales in Blue Jay: Dust energy balance overpredicts IR luminosity in galaxies at z ~ 2.

  Benjamin Collins (Universidad de Chile)

  The spectral energy distribution (SED) of a galaxy encodes vital information about its chemical composition, stellar populations, and dust content. To model the infrared emission, many modern SED-fitting codes rely on dust energy balance, which assumes that all energy absorbed by dust in the UV-optical is equal to the energy emitted in the infrared regime. However, few studies have been carried out to test the validity of this assumption at high redshift, where direct infrared observations are sparse. In this work, we perform aperture photometry in 111 galaxies from the Blue Jay survey (1.7 < z < 3.5) using public JWST/MIRI observations from the PRIMER, COSMOS-Web and COSMOS-3D surveys. By comparing measurements from MIRI to Prospector SED models derived using HST and NIRCam photometry, we find that mid-infrared fluxes are systematically overpredicted by about 10% at 7.7µm up to a factor of ~3 at 21µm. The discrepancy increases with inferred dust attenuation, indicating that dust energy balance suffers from line-of-sight effects in systems with complex dust geometries.

  Adding NIRSpec spectroscopy to the fits breaks parameter degeneracies and reduces the overpredictions by a factor of ~2. When fitting the measured MIRI photometry with the HST and NIRCam data, the resulting best-fit model spectra of dusty galaxies (Av  >1) show significantly lower infrared luminosities (-30%) compared to spectra obtained without MIRI, strongly suggesting that the total energy budget drives the overpredictions. Our study highlights the limitations of dust energy balance at high redshift and underlines the importance of direct observations for accurately recovering the ISM and dust properties of Cosmic Noon galaxies.
• 09.10.2026 - Ronan Kerr (University of Toronto)
• 02.10.2026 -

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