Book Non-Fellow In-person or Online SDM Ticket
Book Fellow In-Person or Online SDM Ticket
Recent spectroscopic observations of distant galaxies from the James Webb Space Telescope (JWST) have posed new questions about the nature of stellar populations. The extreme emission line equivalent widths and ratios, anomalous chemical enrichment patterns (e.g. extreme N/O and C/O ratios), unexpected shapes of the UV/optical continuum, the presence of a strong inverse Balmer break (or “Balmer jump”) features, and the presence of “P-Cygni” and other broad-line features tracing massive star winds (or active galactic nuclei) have all pointed towards the outsized impact of massive, metal poor stars. From a theoretical point of view, there are several competing explanations about these features, including extremely high gas densities, hard ionising spectra from hot stars, and the presence of very massive stars (>100 Msun) or even super massive stars (>1000 Msun).
Observations of the chemical and ionisation properties of high redshift galaxies have also been interpreted as evidence for a “top-heavy” IMF in some extreme systems. Although such top heavy IMFs are generally not seen in star formation events at low redshift, studies of early type galaxies have highlighted that many of these systems, predicted to have formed in extreme events at early cosmic times, also show IMF variations. IMF variations such as these have strong implications on the physics of star-formation in early galaxies and the interpretation of early JWST observations, including the presence of extremely bright galaxies formed within the first few 100 million years after the Big Bang.
This RAS Specialist Meeting will bring together theorists and observers working across high and low redshift observations of these extreme systems, providing a platform to address these critical open questions.
Timetable:
10:00 - 10:30: Welcome/Coffee
10:30 - 11:00: Elizabeth Stanway, An overview of stellar population synthesis and initial mass function uncertainties
11:00 - 11:15: Matthew Bate, Variation of the IMF with redshift and metallicity
11:15 - 11:30: Fergus Cullen, Evidence for an unusual stellar population in an extremely metal-poor galaxy at z=8.3
11:30 - 11:45: Guido Roberts-Borsani, The Nature and Role of Luminous Galaxies from independent Sight Lines
11:45 - 12:00: Sophia Flury, Bringing Theory and Observation Together with Modeling Tools
12:00 - 12:05: Ankur Upadhyaya, Effect of stellar IMF variations on nebular emission lines in both normal and compact sources
12:05 - 12:10: Sophie Newman, Cloudy-Maraston: The Impact of Stellar Rotation and Wolf-Rayet Phase Temperatures on High-Redshift Spectra
12:10 - 12:15: Souradeep Bhattacharya, Probing cosmic chemical enrichment using oxygen and argon abundances
12:15 - 12:30: Karla Ziboney Arellano-Cordova, Exploring the N/O-O/H relation across cosmic time with CLASSY
12:30 - 12:45: Anna McLeod, Can we learn something from resolved massive mstars in the nearby Universe?
12:45 - 13:00: Conor Byrne, How do changes in [alpha/Fe] affect the evolution of massive stars?
13:00 - 14:00: Lunch/Discussion
14:00 - 14:30: Paul Crowther, Properties of metal-poor massive and very-massive stars in the local Universe
14:30 - 14:45: Jorick S Vink, Chemical and ionising feedback from very massive stars
14:45 - 15:00: Anastasia Fialkov, Prospects for constraining the mass distribution of the first stars with 21-cm cosmology
15:00 - 15:15: Yuki Isobe, Averaged Nitrogen Enhancement in High-z Broad-Line AGNs: Insights into Massive Black Hole Seeds
15:15 - 15:20: Storm Colloms, Exploring the Evolution of Massive Stars through Gravitational Wave Observations of Binary Black Holes
15:20 - 15:25: Divyajyoti, Exploring extreme stellar populations with future gravitational wave observatories
15:25 - 16:00: Discussion/Tea
16:00 - 18:00: RAS Monthly A&G Highlights meeting