Shunya Takekawa, Tomoharu Oka, Shiho Tsujimoto, Hiroki Yokozuka, Nanase Harada, Miyuki Kaneko, Rei Enokiya and Yuhei Iwata
{"title":"整个中央分子区氧化硅比率的抛物线趋势:银河中心过去核活动的可能特征","authors":"Shunya Takekawa, Tomoharu Oka, Shiho Tsujimoto, Hiroki Yokozuka, Nanase Harada, Miyuki Kaneko, Rei Enokiya and Yuhei Iwata","doi":"10.3847/2041-8213/ad6c51","DOIUrl":null,"url":null,"abstract":"We report the discovery of a characteristic trend in the intensity ratios of SiO emissions across the Central Molecular Zone (CMZ) of our Galaxy. Using the Nobeyama Radio Observatory 45 m telescope, we conducted large-scale, high-sensitivity imaging observations in molecular lines including SiO J = 2–1 and CS J = 2–1. By identifying SiO-emitting clouds and examining their intensity ratios relative to the other molecular lines, we unveiled a parabolic-like trend showing lower ratios near the Galactic nucleus, Sgr A*, with gradual increases toward the edges of the CMZ. This pattern suggests a possible outburst of the nucleus within the last ∼105 yr, which may have propagated through the entire CMZ with strong shocks. Alternatively, the observed trend may also be attributed to the destruction of small dust grains by high-energy photons. Our results can potentially lead to a new perspective on the history of nuclear activity and its impact on the surrounding molecular environment.","PeriodicalId":501814,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"2024-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Parabolic-like Trend in SiO Ratios throughout the Central Molecular Zone: Possible Signature of a Past Nuclear Activity in the Galactic Center\",\"authors\":\"Shunya Takekawa, Tomoharu Oka, Shiho Tsujimoto, Hiroki Yokozuka, Nanase Harada, Miyuki Kaneko, Rei Enokiya and Yuhei Iwata\",\"doi\":\"10.3847/2041-8213/ad6c51\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"We report the discovery of a characteristic trend in the intensity ratios of SiO emissions across the Central Molecular Zone (CMZ) of our Galaxy. Using the Nobeyama Radio Observatory 45 m telescope, we conducted large-scale, high-sensitivity imaging observations in molecular lines including SiO J = 2–1 and CS J = 2–1. By identifying SiO-emitting clouds and examining their intensity ratios relative to the other molecular lines, we unveiled a parabolic-like trend showing lower ratios near the Galactic nucleus, Sgr A*, with gradual increases toward the edges of the CMZ. This pattern suggests a possible outburst of the nucleus within the last ∼105 yr, which may have propagated through the entire CMZ with strong shocks. Alternatively, the observed trend may also be attributed to the destruction of small dust grains by high-energy photons. Our results can potentially lead to a new perspective on the history of nuclear activity and its impact on the surrounding molecular environment.\",\"PeriodicalId\":501814,\"journal\":{\"name\":\"The Astrophysical Journal Letters\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":0.0000,\"publicationDate\":\"2024-08-20\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"The Astrophysical Journal Letters\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/10.3847/2041-8213/ad6c51\",\"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 Letters","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.3847/2041-8213/ad6c51","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
Parabolic-like Trend in SiO Ratios throughout the Central Molecular Zone: Possible Signature of a Past Nuclear Activity in the Galactic Center
We report the discovery of a characteristic trend in the intensity ratios of SiO emissions across the Central Molecular Zone (CMZ) of our Galaxy. Using the Nobeyama Radio Observatory 45 m telescope, we conducted large-scale, high-sensitivity imaging observations in molecular lines including SiO J = 2–1 and CS J = 2–1. By identifying SiO-emitting clouds and examining their intensity ratios relative to the other molecular lines, we unveiled a parabolic-like trend showing lower ratios near the Galactic nucleus, Sgr A*, with gradual increases toward the edges of the CMZ. This pattern suggests a possible outburst of the nucleus within the last ∼105 yr, which may have propagated through the entire CMZ with strong shocks. Alternatively, the observed trend may also be attributed to the destruction of small dust grains by high-energy photons. Our results can potentially lead to a new perspective on the history of nuclear activity and its impact on the surrounding molecular environment.