Tian-Yu Tu, 天宇 涂, Prathap Rayalacheruvu, Liton Majumdar, Yang Chen, 阳 陈, Ping Zhou, 平 周 and Miguel Santander-García
{"title":"对超新星残留物 3C 391 的非震荡分子云的叶贝斯 W 波段线测量:宇宙射线诱导化学的证据","authors":"Tian-Yu Tu, 天宇 涂, Prathap Rayalacheruvu, Liton Majumdar, Yang Chen, 阳 陈, Ping Zhou, 平 周 and Miguel Santander-García","doi":"10.3847/1538-4357/ad74fb","DOIUrl":null,"url":null,"abstract":"Cosmic rays (CRs) have strong influences on the chemistry of dense molecular clouds (MCs). To study the detailed chemistry induced by CRs, we conducted a Yebes W-band line survey towards an unshocked MC (which we named 3C391:NML) associated with supernova remnant 3C 391. We detected emission lines of 18 molecular species in total and estimated their column densities with local thermodynamic equilibrium (LTE) and non-LTE analysis. Using the abundance ratio N(HCO+)/N(CO) and an upper limit of N(DCO+)/N(HCO+), we estimated that the CR ionization rate of 3C391:NML is ζ ≳ 2.7 × 10−14 s−1 with an analytic method. However, we caution against adopting this value because chemical equilibrium, which is a prerequisite of using the equations, is not necessarily reached in 3C391:NML. We observed lower N(HCO+)/N(HOC+), higher N(HCS+)/N(CS), and higher X(l-C3H+) by an order of magnitude in 3C391:NML than the typical values in quiescent dense MCs. We found that an enhanced CR ionization rate (of order ∼10−15 or ∼10−14 s−1) is needed to reproduce the observation with a chemical model. This is higher than the values found in typical MCs by 2–3 orders of magnitude.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"2024-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"A Yebes W-band Line Survey towards an Unshocked Molecular Cloud of Supernova Remnant 3C 391: Evidence of Cosmic-Ray-Induced Chemistry\",\"authors\":\"Tian-Yu Tu, 天宇 涂, Prathap Rayalacheruvu, Liton Majumdar, Yang Chen, 阳 陈, Ping Zhou, 平 周 and Miguel Santander-García\",\"doi\":\"10.3847/1538-4357/ad74fb\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"Cosmic rays (CRs) have strong influences on the chemistry of dense molecular clouds (MCs). To study the detailed chemistry induced by CRs, we conducted a Yebes W-band line survey towards an unshocked MC (which we named 3C391:NML) associated with supernova remnant 3C 391. We detected emission lines of 18 molecular species in total and estimated their column densities with local thermodynamic equilibrium (LTE) and non-LTE analysis. Using the abundance ratio N(HCO+)/N(CO) and an upper limit of N(DCO+)/N(HCO+), we estimated that the CR ionization rate of 3C391:NML is ζ ≳ 2.7 × 10−14 s−1 with an analytic method. However, we caution against adopting this value because chemical equilibrium, which is a prerequisite of using the equations, is not necessarily reached in 3C391:NML. We observed lower N(HCO+)/N(HOC+), higher N(HCS+)/N(CS), and higher X(l-C3H+) by an order of magnitude in 3C391:NML than the typical values in quiescent dense MCs. We found that an enhanced CR ionization rate (of order ∼10−15 or ∼10−14 s−1) is needed to reproduce the observation with a chemical model. This is higher than the values found in typical MCs by 2–3 orders of magnitude.\",\"PeriodicalId\":501813,\"journal\":{\"name\":\"The Astrophysical Journal\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":0.0000,\"publicationDate\":\"2024-10-15\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"The Astrophysical Journal\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/10.3847/1538-4357/ad74fb\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"The Astrophysical Journal","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.3847/1538-4357/ad74fb","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
A Yebes W-band Line Survey towards an Unshocked Molecular Cloud of Supernova Remnant 3C 391: Evidence of Cosmic-Ray-Induced Chemistry
Cosmic rays (CRs) have strong influences on the chemistry of dense molecular clouds (MCs). To study the detailed chemistry induced by CRs, we conducted a Yebes W-band line survey towards an unshocked MC (which we named 3C391:NML) associated with supernova remnant 3C 391. We detected emission lines of 18 molecular species in total and estimated their column densities with local thermodynamic equilibrium (LTE) and non-LTE analysis. Using the abundance ratio N(HCO+)/N(CO) and an upper limit of N(DCO+)/N(HCO+), we estimated that the CR ionization rate of 3C391:NML is ζ ≳ 2.7 × 10−14 s−1 with an analytic method. However, we caution against adopting this value because chemical equilibrium, which is a prerequisite of using the equations, is not necessarily reached in 3C391:NML. We observed lower N(HCO+)/N(HOC+), higher N(HCS+)/N(CS), and higher X(l-C3H+) by an order of magnitude in 3C391:NML than the typical values in quiescent dense MCs. We found that an enhanced CR ionization rate (of order ∼10−15 or ∼10−14 s−1) is needed to reproduce the observation with a chemical model. This is higher than the values found in typical MCs by 2–3 orders of magnitude.