Low-metallicity massive single stars with rotation III. Source of ionization and C IV emission in I Zw 18

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A_____%2F25%3A00643351" target="_blank" >RIV/67985815:_____/25:00643351 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/00216224:14310/25:00144630

Výsledek na webu

<a href="https://hdl.handle.net/11104/0373288" target="_blank" >https://hdl.handle.net/11104/0373288</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1051/0004-6361/202452483" target="_blank" >10.1051/0004-6361/202452483</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Low-metallicity massive single stars with rotation III. Source of ionization and C IV emission in I Zw 18

Popis výsledku v původním jazyce

Context. Chemically homogeneously evolving stars have been proposed to account for several exotic phenomena, including gravitational-wave emissions, gamma-ray bursts and certain types of supernovae. Aims. Here we study whether these stars can explain the observations of the metal-poor star-forming dwarf galaxy, I Zwicky 18. Methods. We apply our synthetic spectral models from Paper II to (i) establish a classification sequence for these hot stars, (ii) predict the photonionizing flux and the strength of observable emission lines from a I Zw 18-like stellar population, and (iii) compare our predictions to all available observations of this galaxy. Results. Adding two new models computed with PoWR, we report that (i) these stars follow a unique sequence of classes: O> WN> WO (i.e. without ever being WC). From our population synthesis with standard assumptions, we predict that (ii) the source of the UV C IV lambda 1550 Å and other emission bumps is a couple of dozen WO-type Wolf-Rayet stars (not WC as previously assumed) which are the result of chemically homogeneous evolution, while these, combined with the rest of the O-star population, account for the high He II ionizing flux and the spectral hardness. Contrasting our results against published optical and UV data from the literature and accounting for different aperture sizes and spatial regions probed by the observations, we find that (iii) our models are highly consistent with existing measurements. Conclusions. Since our massive Pop II stars might just as well exist in early star-forming regions, our findings have implications for upcoming James Webb Space Telescope (JWST) surveys: the first galaxies in the high-redshift Universe may also experience the extra contribution of UV photons and the kinds of exotic explosions that chemically homogeneous stellar evolution predicts. Given that our results apply for binary populations too as long as the same fraction (10%) of the systems evolves chemically homogeneously, we conclude that the stellar progenitors of gravitational waves may very well exist today in I Zw 18.

Název v anglickém jazyce

Low-metallicity massive single stars with rotation III. Source of ionization and C IV emission in I Zw 18

Popis výsledku anglicky

Context. Chemically homogeneously evolving stars have been proposed to account for several exotic phenomena, including gravitational-wave emissions, gamma-ray bursts and certain types of supernovae. Aims. Here we study whether these stars can explain the observations of the metal-poor star-forming dwarf galaxy, I Zwicky 18. Methods. We apply our synthetic spectral models from Paper II to (i) establish a classification sequence for these hot stars, (ii) predict the photonionizing flux and the strength of observable emission lines from a I Zw 18-like stellar population, and (iii) compare our predictions to all available observations of this galaxy. Results. Adding two new models computed with PoWR, we report that (i) these stars follow a unique sequence of classes: O> WN> WO (i.e. without ever being WC). From our population synthesis with standard assumptions, we predict that (ii) the source of the UV C IV lambda 1550 Å and other emission bumps is a couple of dozen WO-type Wolf-Rayet stars (not WC as previously assumed) which are the result of chemically homogeneous evolution, while these, combined with the rest of the O-star population, account for the high He II ionizing flux and the spectral hardness. Contrasting our results against published optical and UV data from the literature and accounting for different aperture sizes and spatial regions probed by the observations, we find that (iii) our models are highly consistent with existing measurements. Conclusions. Since our massive Pop II stars might just as well exist in early star-forming regions, our findings have implications for upcoming James Webb Space Telescope (JWST) surveys: the first galaxies in the high-redshift Universe may also experience the extra contribution of UV photons and the kinds of exotic explosions that chemically homogeneous stellar evolution predicts. Given that our results apply for binary populations too as long as the same fraction (10%) of the systems evolves chemically homogeneously, we conclude that the stellar progenitors of gravitational waves may very well exist today in I Zw 18.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10308 - Astronomy (including astrophysics,space science)

Projekt

<a href="/cs/project/GA25-15910S" target="_blank" >GA25-15910S: Větry horkých hvězd: řešení nejistot ztráty hmoty v blízkosti Eddingtonovy limity</a><br>

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2025

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Astronomy & Astrophysics

ISSN

0004-6361

e-ISSN

1432-0746

Svazek periodika

703

Číslo periodika v rámci svazku

Nov.

Stát vydavatele periodika

FR - Francouzská republika

Počet stran výsledku

18

Strana od-do

A131

Kód UT WoS článku

001616252400004

EID výsledku v databázi Scopus

2-s2.0-105021945501