Seminare und Vorlesungen

Gastgeber: MPA

The Hunt for Lensed Quasars and Weak-Line Active Galaxies at Cosmic Dawn

MPA Institute Seminar - Hybrid

Sensitivity of Euclid strong lens observations to dark matter substructure

Munich/Garching Dark Matter Meeting - Hybrid
Abstract: Euclid will image 10^5 new strong lenses at ~100mas resolution, providing a dataset of unprecedented size with which to search for dark matter subhaloes and test CDM. However, traditional methods for subhalo detection cannot scale to a dataset of this size. We introduce a machine learning method for estimating the sensitivity of strong lens images to dark matter subhaloes in the lens. We then estimate the sensitivity in 16,000 simulated Euclid strong lens observations, to determine how useful Euclid is for constraining DM models in this way. We find that, assuming a 3 sigma detection threshold, 2.35 per cent of the area inside twice the Einstein radius is sensitive enough to detect a subhalo with M_max = 10^10 M_sun. The best pixel in the dataset is sensitive at M_max = 10^(8.8±0.2) M_sun. We find that, assuming CDM, the average Euclid lens should have 0.0143 detectable subhaloes, or one detection in every ~70 lenses. However, in the most sensitive lenses, this increases dramatically to 0.356 detectable subhaloes, or one for every ~3 lenses. Assuming Euclid discovers 170,000 strong lenses as predicted, we expcet ~2500 new subhalo detections. However, the sensitivity limit that we find means these detections cannot differentiate between CDM and WDM models, although they can place strong constraints on the normalisation of the subhalo mass function. [mehr]

Star cluster formation, feedback and evolution across cosmic times

MPA Special Seminar on Galaxy Formation
In the era of multi wavelength surveys of unprecedented sensitivity and spatial resolution, we are now able to map star cluster formation from the very early phases (deeply embedded in their natal giant molecular clouds) as well as study their feedback on the interstellar medium not only in the local universe but across cosmic times. I will present some key results obtained from our initial JWST observations of the nearby galaxy NGC628. Combinations of NIR and MIR colors as well as MIR emission lines like Br_alpha and the 3.35 micron PAH band help us, for the first time, to fully map the star clusters from deeply embedded phases to late stages, when AGB stars dominate their colors. Comparisons between observed IR colors and stellar evolutionary tracks show how current stellar evolutionary models fail to reproduce all the cluster’s phases. I will show results that link cluster feedback to different ISM phases from 10s to 100 s of parsec scales. I will discuss how studying star clusters in the local universe remains a fundamental laboratory for understanding cluster formation and evolution in rapidly evolving galaxies across cosmic time. Gravitational telescopes and JWST capabilities have opened a new era for cluster studies in young galaxies. I will present our initial study of star clusters and stellar clumps in galaxies between redshift 1 and 6 that help us to reconstruct the conditions where proto-globular clusters formed. [mehr]

How well-intentioned white male physicists maintain ignorance of inequality and justify inaction

MPA Gender/Diversity Forum - virtual
  • Datum: 07.12.2022
  • Uhrzeit: 16:00 - 17:00
  • Vortragende(r): Melissa Dancy (Western Michigan Univ.)
  • About the speaker: Dr. Dancy is a principal research associate in the evaluation center at Western Michigan University. She holds a Ph.D. in physics and has been an active member of the physics education research community for more than 25 years. Throughout her career, she has always been drawn to research projects that focus on improving higher education STEM classrooms and working environments by improving teaching and/or addressing inequity. Dr. Dancy has over 70 peer-reviewed or invited publications related to educational transformation, faculty development, and equity. Dr. Dancy also frequently serves as an external evaluator on NSF-funded education-related projects.
  • Raum: online only
  • Gastgeber: MPA
Abstract: Inequity in physics remains a problem despite significant effort, care, and material resources dedicated to addressing it. The tendency to focus change efforts on the oppressed while leaving people and structures of power unexamined is likely related to the slow progress. In this talk, I present data from multiple studies considering how those who hold intersecting identities of privilege engage with equity efforts. Findings highlight how well-meaning people of privilege frequently undermine equity by failing to acknowledge even obvious inequity, distancing themselves from both the causes and solutions of inequity, minimizing it when they can not deny or distance, and justifying their own inaction. I end by offering recommendations for both individuals of privilege as well as recommendations for policymakers. [mehr]

Star cluster formation, feedback and evolution across cosmic times

Special MPA Seminar - Hybrid
Abstract: In the era of multi wavelength surveys of unprecedented sensitivity and spatial resolution, we are now able to map star cluster formation from the very early phases (deeply embedded in their natal giant molecular clouds) as well as study their feedback on the interstellar medium not only in the local universe but across cosmic times. I will present some key results obtained from our initial JWST observations of the nearby galaxy NGC628. Combinations of NIR and MIR colors as well as MIR emission lines like Br_alpha and the 3.35 micron PAH band help us, for the first time, to fully map the star clusters from deeply embedded phases to late stages, when AGB stars dominate their colors. Comparisons between observed IR colors and stellar evolutionary tracks show how current stellar evolutionary models fail to reproduce all the cluster’s phases. I will show results that link cluster feedback to different ISM phases from 10s to 100 s of parsec scales. I will discuss how studying star clusters in the local universe remains a fundamental laboratory for understanding cluster formation and evolution in rapidly evolving galaxies across cosmic time. Gravitational telescopes and JWST capabilities have opened a new era for cluster studies in young galaxies. I will present our initial study of star clusters and stelar clumps in galaxies between redshift 1 and 6 that help us to reconstruct the conditions where proto-globular clusters formed. [mehr]
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