تقرير
Elevated Hot Gas and High-Mass X-ray Binary Emission in Low Metallicity Galaxies: Implications for Nebular Ionization and Intergalactic Medium Heating in the Early Universe
| العنوان: | Elevated Hot Gas and High-Mass X-ray Binary Emission in Low Metallicity Galaxies: Implications for Nebular Ionization and Intergalactic Medium Heating in the Early Universe |
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| المؤلفون: | Lehmer, Bret D., Eufrasio, Rafael T., Basu-Zych, Antara, Garofali, Kristen, Gilbertson, Woodrow, Mesinger, Andrei, Yukita, Mihoko |
| سنة النشر: | 2022 |
| المجموعة: | Astrophysics |
| مصطلحات موضوعية: | Astrophysics - Astrophysics of Galaxies, Astrophysics - Cosmology and Nongalactic Astrophysics |
| الوصف: | High-energy emission associated with star formation has been proposed as a significant source of interstellar medium (ISM) ionization in low-metallicity starbursts and an important contributor to the heating of the intergalactic medium (IGM) in the high-redshift ($z > 8$) Universe. Using Chandra observations of a sample of 30 galaxies at $D \approx$~200--450 Mpc that have high specific star-formation rates of 3--9 Gyr$^{-1}$ and metallicities near $Z \approx 0.3 Z_\odot$, we provide new measurements of the average 0.5--8 keV spectral shape and normalization per unit star-formation rate (SFR). We model the sample-combined X-ray spectrum as a combination of hot gas and high-mass X-ray binary (HMXB) populations and constrain their relative contributions. We derive scaling relations of $\log L_{\rm 0.5-8 keV}^{\rm HMXB}$/SFR $= 40.19 \pm 0.06$ and $\log L_{\rm 0.5-2 keV}^{\rm gas}$/SFR $= 39.58^{+0.17}_{-0.28}$; significantly elevated compared to local relations. The HMXB scaling is also somewhat higher than $L_{\rm 0.5-8 keV}^{\rm HMXB}$-SFR-$Z$ relations presented in the literature, potentially due to our galaxies having relatively low HMXB obscuration and young and X-ray luminous stellar populations. The elevation of the hot gas scaling relation is at the level expected for diminished attenuation due to a reduction of metals; however, we cannot conclude that an $L_{\rm 0.5-2 keV}^{\rm gas}$-SFR-$Z$ relation is driven solely by changes in ISM metal content. Finally, we present SFR-scaled spectral models (both emergent and intrinsic) that span the X-ray--to--IR band, providing new benchmarks for studies of the impact of ISM ionization and IGM heating in the early Universe. Comment: Accepted for publication in ApJ (25 pages, 9 figures, and 4 tables) |
| نوع الوثيقة: | Working Paper |
| DOI: | 10.3847/1538-4357/ac63a7 |
| URL الوصول: | http://arxiv.org/abs/2203.16566 |
| رقم الأكسشن: | edsarx.2203.16566 |
| قاعدة البيانات: | arXiv |
| DOI: | 10.3847/1538-4357/ac63a7 |
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