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BEGIN:VEVENT
DTSTART;TZID=Atlantic/Canary:20230411T123000
DTEND;TZID=Atlantic/Canary:20230411T133000
UID:iactalks-1673
X-WR-CALNAME: IAC Talks: Open Astronomy Seminars
X-ORIGINAL-URL: /iactalks/Talks/view/1673
CREATED:2023-04-11T12:30:00+01:00
X-WR-CALDESC: IAC Talks upcomming talks
SUMMARY: A new, multi-cloud method to accurately model emission lines in st
 ar-forming galaxies
DESCRIPTION: A new, multi-cloud method to accurately model emission lines i
 n star-forming galaxies\nDr. Amirnezam Amiri\n\n \nThe abundance of c
 hemical elements across cosmic time provide unique information on the phys
 ical processes driving the evolution of galaxies. Current methods for meas
 uring gas-phase metallicities, based on either direct measurements of elec
 tron temperature (Te) or calibrations from strong nebular emission line ra
 tios, are based on simplifying assumptions and do not adequately describe 
 the complexity of the emitting regions. We present a new approach based on
  fitting galaxy spectra with multi-cloud photoionisation models. Unlike cu
 rrent methods, based on comparisons with single-cloud models, our methodol
 ogy is able to reproduce all observed emission lines to a very high accura
 cy, down to a few percent, thus allowing for accurate metallicity measurem
 ents. We further recover the well known trends between ionization paramete
 r and metallicity, and between the Nitrogen and Oxygen abundances. Our mod
 els accurately reproduce the auroral-to-nebular line ratios, while the res
 ults of the standard Te method are sometimes very different from the 
 best-fitting model metallity. We finally present newly calibrated metallic
 ity estimators for galaxies based on ratios between strong emission lines.
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