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SUMMARY:CORN - Chronometers Of Relic Nature: Estimate of the expansion rat
 e of the Universe using compact relic galaxies
DTSTART;VALUE=DATE-TIME:20260915T081500Z
DTEND;VALUE=DATE-TIME:20260915T084000Z
DTSTAMP;VALUE=DATE-TIME:20261026T145938Z
UID:indico-contribution-31272@indico.ific.uv.es
DESCRIPTION:Speakers: Krzysztof Lisiecki (National Centre for Nuclear Rese
 rach\, Poland)\nThe persistent discrepancy between the locally measured Hu
 bble constant\, derived from Cepheids and Type Ia supernovae\, and the val
 ue inferred from the cosmic microwave background underscores the need for 
 independent cosmological probes. Cosmic chronometers provide a direct\, mo
 del-independent measurement of the expansion history\, but their accuracy 
 is currently limited by systematic uncertainties in stellar population mod
 elling\, particularly when the full red and quiescent population is used. 
 \nI propose an alternative chronometer strategy based on relic galaxies: t
 he oldest\, most compact\, and most dynamically evolved systems at a given
  epoch. These galaxies are expected to host uniformly old\, rapidly formed
  stellar populations with minimal subsequent mass growth\, making them clo
 ser to ideal single-burst populations. By focusing on this population\, we
  can reduce uncertainties associated with composite star formation histori
 es and mitigate biases arising from late-time rejuvenation.\nIn this work 
 I use the largest catalogue of relics\, to construct a cleaner differentia
 l age–redshift relation. Particular emphasis will be placed on assessing
  the limitations of current single stellar population models\, including m
 etallicity\, initial mass function\, and alpha-enrichment. By quantifying 
 how these ingredients affect absolute and differential age estimates\, we 
 aim to establish a more robust systematic floor for the chronometer method
 . A relic-based approach has the potential to tighten stellar age constrai
 nts at fixed redshift\, refine the expansion history measurement\, and pro
 vide an independent perspective on the Hubble tension.\n\nhttps://indico.i
 fic.uv.es/event/8160/contributions/31272/
LOCATION:
URL:https://indico.ific.uv.es/event/8160/contributions/31272/
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