X-ray absorption of cold gas: Simulating interstellar molecular clouds in the laboratory
| Autor: | Gissis, Itay, Fisher, Amnon, Behar, Ehud |
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| Rok vydání: | 2021 |
| Předmět: | |
| Zdroj: | Phys. Rev. E 104, 015205 (2021) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevE.104.015205 |
| Popis: | Galactic and extra-galactic sources produce X-rays that are often absorbed by molecules and atoms in giant molecular clouds (GMCs), which provides valuable information about their composition and physical state. We mimic this phenomenon with a laboratory Z-pinch X-ray source, which is impinged on neutral molecular gas. The novel technique produces a soft X-ray pseudo continuum using a pulsed-current generator. The absorbing gas is injected from a 1 cm long planar gas-puff without any window or vessel along the line of sight. An X-ray spectrometer with a resolving power of $\lambda/\Delta\lambda\sim$420, comparable to that of astrophysical space instruments, records the absorbed spectra. This resolution clearly resolves the molecular lines from the atomic lines; therefore, motivating the search of molecular signature in astrophysical X-ray spectra. The experimental setup enables different gas compositions and column densities. K-shell spectra of CO$_2$, N$_2$ and O$_2$ reveal a plethora of absorption lines and photo-electric edges measured at molecular column densities between $\sim$10$^{16}$ cm$^{-2}$ -- 10$^{18}$ cm$^{-2}$ typical of GMCs. We find that the population of excited-states, contributing to the edge, increases with gas density. Comment: Accepted for publication in PRE ref: LC18406E |
| Databáze: | arXiv |
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