Evidence for the First Extragalactic Hydrogen Recombination Line Maser in NGC 253
| Autor: | Jesús Martín-Pintado, Izaskun Jiménez-Serra, A. Báez-Rubio, Fernando Rico-Villas |
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| Rok vydání: | 2018 |
| Předmět: |
Astrophysics::High Energy Astrophysical Phenomena
FOS: Physical sciences Astrophysics::Cosmology and Extragalactic Astrophysics Astrophysics 01 natural sciences law.invention law Ionization 0103 physical sciences Astrophysics::Solar and Stellar Astrophysics Continuum (set theory) Maser 010303 astronomy & astrophysics Astrophysics::Galaxy Astrophysics Line (formation) Physics Spectral index 010308 nuclear & particles physics Astronomy and Astrophysics Astrophysics - Astrophysics of Galaxies Galaxy Delta-v (physics) Stars Space and Planetary Science Astrophysics of Galaxies (astro-ph.GA) High Energy Physics::Experiment |
| Zdroj: | The Astrophysical Journal. 867:L6 |
| ISSN: | 2041-8213 |
| Popis: | We present the first detection of extragalactic hydrogen recombination line maser emission in the H26alpha transition toward the inner 13.5 pc nuclear region of the starburst galaxy NGC 253 using ALMA data. In regions with complex continuum emission (dust, free-free and synchrotron) we propose to use the recombination line spectral index, $\alpha_\mathrm{L}$ ($S_\mathrm{L}\cdot \Delta v \propto \nu^{\alpha_\mathrm{L}}$), between the H30alpha and the H26alpha lines to study the structure of ultra-compact HII regions and to identify maser emission ($\alpha_\mathrm{L}> 2.1$) from ionized winds. The measured values of $\alpha_\mathrm{L}$ ranged from 1.0 to 2.9. The largest $\alpha_\mathrm{L}$ can only be explained by maser emission. The measured flux density in the H26$\alpha$ maser in NGC 253 suggests that we are observing hundreds of stars like MWC349A, a prototypical stellar wind where maser emission arises from its circumstellar disk. We briefly discuss the implication of the detection of maser emission in starburst galaxies like NGC 253. Comment: 3 figures |
| Databáze: | OpenAIRE |
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