Roberto Galván-Madrid, Daniel J. Díaz-González, Frédérique Motte, Adam Ginsburg, Nichol Cunningham, Karl M. Menten, Mélanie Armante, Mélisse Bonfand, Jonathan Braine, Timea Csengeri, Pierre Dell’Ova, Fabien Louvet, Thomas Nony, Rudy Rivera-Soto, Patricio Sanhueza, Amelia M. Stutz, Friedrich Wyrowski, Rodrigo H. Álvarez-Gutiérrez, Tapas Baug, Sylvain Bontemps, Leonardo Bronfman, Manuel Fernández-López, Antoine Gusdorf, Atanu Koley, Hong-Li Liu, Javiera Salinas, Allison P. M. Towner, Anthony P. Whitworth
{"title":"ALMA-IMF. XIV. Free–Free Templates Derived from H41α and Ionized Gas Content in 15 Massive Protoclusters","authors":"Roberto Galván-Madrid, Daniel J. Díaz-González, Frédérique Motte, Adam Ginsburg, Nichol Cunningham, Karl M. Menten, Mélanie Armante, Mélisse Bonfand, Jonathan Braine, Timea Csengeri, Pierre Dell’Ova, Fabien Louvet, Thomas Nony, Rudy Rivera-Soto, Patricio Sanhueza, Amelia M. Stutz, Friedrich Wyrowski, Rodrigo H. Álvarez-Gutiérrez, Tapas Baug, Sylvain Bontemps, Leonardo Bronfman, Manuel Fernández-López, Antoine Gusdorf, Atanu Koley, Hong-Li Liu, Javiera Salinas, Allison P. M. Towner, Anthony P. Whitworth","doi":"10.3847/1538-4365/ad61e6","DOIUrl":null,"url":null,"abstract":"We use the H41<italic toggle=\"yes\">α</italic> recombination line to create templates of the millimeter free–free emission in the ALMA-IMF continuum maps, which allows us to separate it from dust emission. This method complements spectral-index information and extrapolation from centimeter-wavelength maps. We use the derived maps to estimate the properties of up to 34 H <sc>ii</sc> regions across the ALMA-IMF protoclusters. The hydrogen ionizing photon rate <italic toggle=\"yes\">Q</italic>\n<sub>0</sub> and spectral types follow the evolutionary trend proposed by Motte et al. The youngest protoclusters lack detectable ionized gas, followed by protoclusters with increasing numbers of OB stars. The total <italic toggle=\"yes\">Q</italic>\n<sub>0</sub> increases from ∼10<sup>45</sup> s<sup>−1</sup> to >10<sup>49</sup> s<sup>−1</sup>. We used the adjacent He41<italic toggle=\"yes\">α</italic> line to measure the relative number abundances of helium, finding values consistent with the Galactic interstellar medium, although a few outliers are discussed. A search for sites of maser amplification of the H41<italic toggle=\"yes\">α</italic> line returned negative results. We looked for possible correlations between the electron densities, emission measures, and <italic toggle=\"yes\">Q</italic>\n<sub>0</sub> with H <sc>ii</sc> region size <italic toggle=\"yes\">D</italic>. The latter is the best correlated, with <italic toggle=\"yes\">Q</italic>\n<sub>0</sub> ∝ <italic toggle=\"yes\">D</italic>\n<sup>2.49 ± 0.18</sup>. This favors interpretations in which smaller ultracompact H <sc>ii</sc> regions are not necessarily the less dynamically evolved versions of larger ones but rather are ionized by less massive stars. Moderate correlations were found between the dynamical width Δ<italic toggle=\"yes\">V</italic>\n<sub>dyn</sub> with <italic toggle=\"yes\">D</italic> and <italic toggle=\"yes\">Q</italic>\n<sub>0</sub>. Δ<italic toggle=\"yes\">V</italic>\n<sub>dyn</sub> increases from about 1 to 2 times the ionized-gas sound speed. Finally, an outlier H <sc>ii</sc> region south of W43-MM2 is discussed. We suggest that this source could harbor an embedded stellar or disk wind.","PeriodicalId":22368,"journal":{"name":"The Astrophysical Journal Supplement Series","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"The Astrophysical Journal Supplement Series","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.3847/1538-4365/ad61e6","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
We use the H41α recombination line to create templates of the millimeter free–free emission in the ALMA-IMF continuum maps, which allows us to separate it from dust emission. This method complements spectral-index information and extrapolation from centimeter-wavelength maps. We use the derived maps to estimate the properties of up to 34 H ii regions across the ALMA-IMF protoclusters. The hydrogen ionizing photon rate Q0 and spectral types follow the evolutionary trend proposed by Motte et al. The youngest protoclusters lack detectable ionized gas, followed by protoclusters with increasing numbers of OB stars. The total Q0 increases from ∼1045 s−1 to >1049 s−1. We used the adjacent He41α line to measure the relative number abundances of helium, finding values consistent with the Galactic interstellar medium, although a few outliers are discussed. A search for sites of maser amplification of the H41α line returned negative results. We looked for possible correlations between the electron densities, emission measures, and Q0 with H ii region size D. The latter is the best correlated, with Q0 ∝ D2.49 ± 0.18. This favors interpretations in which smaller ultracompact H ii regions are not necessarily the less dynamically evolved versions of larger ones but rather are ionized by less massive stars. Moderate correlations were found between the dynamical width ΔVdyn with D and Q0. ΔVdyn increases from about 1 to 2 times the ionized-gas sound speed. Finally, an outlier H ii region south of W43-MM2 is discussed. We suggest that this source could harbor an embedded stellar or disk wind.
我们利用 H41α 重组线为 ALMA-IMF 连续波图中的毫米自由发射创建模板,从而将其与尘埃发射区分开来。这种方法是对光谱指数信息和厘米波地图推断的补充。我们利用得出的地图估算了 ALMA-IMF 原型星团中多达 34 个 H ii 区域的性质。最年轻的原星团缺乏可探测到的电离气体,随后是OB星数量不断增加的原星团。总 Q0 从 ∼1045 s-1 增加到 >1049 s-1。我们利用邻近的 He41α 线测量了氦的相对数量丰度,发现其值与银河系星际介质一致,但也讨论了一些异常值。对 H41α 线的 maser 放大点的搜索结果是否定的。我们寻找了电子密度、发射测量值和 Q0 与 H ii 区域大小 D 之间可能存在的相关性。这有利于这样一种解释,即较小的超紧密 H ii 区域并不一定是较大区域的低动力学演化版本,而是由质量较小的恒星电离而成的。在动力学宽度 ΔVdyn 与 D 和 Q0 之间发现了适度的相关性。ΔVdyn从电离气体声速的约1倍增加到2倍。最后,讨论了 W43-MM2 南部的一个离群 H ii 区域。我们认为这个星源可能蕴藏着一个嵌入式恒星风或盘风。