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| Paper: |
Stars and Stellar Black Holes in the Low-metallicity Galaxy I Zw 18 |
| Volume: |
519, Radiative Signatures from the Cosmos |
| Page: |
267 |
| Authors: |
Heap, S. R.; Hubeny, I.; Lanz, T. M. |
| Abstract: |
I Zw 18 is a star-forming dwarf galaxy having a very low metal
content, O/H ∼ 1/50 solar (Skillman & Kennicutt 1993). While galaxies
with such low metallicity are rare in the low-redshift universe, they
are likely to be common in galaxies at cosmic dawn. Thus, I Zw 18 is a
“living” template for z > 6 galaxies. We have obtained HST/COS far-UV
spectra of the northwest star cluster in I Zw 18 and have compared
them to SYNSPEC model spectra by Lanz & Hubeny (2003, 2007) in order
to determine the properties of the stellar population. We have also
compared the observed spectra of I Zw 18-NW to the CLOUDSPEC models (Hubeny et al. 2000) of the stellar cluster with an embedded
ultra-luminous X-ray source (ULX). This comparison reveals feedback of
the stellar black hole in the form of photoionization and
heating. Such models can be used as starting points to explore the
physical conditions in which stars and black holes form and evolve in
an extremely low-metallicity environment at high redshift. |
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