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Register a new userFingerprinting the effects of hyperfine structure on CH and OH far infrared spectra using Wiener filter deconvolution
تطبيق تشفير البصمات على تأثيرات الهيبرفاين ستروكتور على طيف الأبعاد البعيدة ل CH و OH باستخدام تصفية وينر التحليل المحلل
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في هذه الورقة، نحاول دراسة تأثير التفرع الهايبرفاين على الخطوط الطيفية المعقدة، مع الغرض من تقدير التراكيز الكانونية من خلال فصل تبعيتها على البنيويات الهايبرفاين. ويتم الحصول على هذا من المبادئ الأولية من خلال فصل التحليل. نقدم الملاحظات بدقة عالية للحالات الأساسية لتحرك CH بالقرب من 2 THz التي تم الإبحار بها نحو مصادر الاستمرارية الشديدة في الأشعة فوق البنفسجية، AGAL010.62$-$00.384، AGAL034.258+00.154، AGAL327.293$-$00.579، AGAL330.954$-$00.182، AGAL332.826$-$00.549، AGAL351.581$-$00.352 و SgrB2 (M). وقد تم الملاحظة لهذه الخطوط مع جهاز GREAT على متن طائرة SOFIA. وقد تم فصل الملاحظات المحلية لCH من بصمة الهايبرفاين باستخدام فلتر وينر، نواة محسنة تعمل على فصل التحليل المباشر. وتتطلب التحليل الكمي للطيفات المفصلة أولاً حساب تراكيز N (CH). وتشكل القيم الموثوقة لـ N (CH) من الأهمية بسبب حالة CH كمشيط بارز لـ H_2 في المناطق المتجانسة من الفضاء الخارجي. وتظهر نسبة N (OH) / N (CH) تختلف بمقدار يصل إلى أضعاف واحدة، للمصادر الفردية التي تقع خارج مركز المجرة. وباستخدام CH كمشيط لـ H_2، تم تحديد التركيز النسبي لجزيئات OH بقيمة X (OH) = 1.09 × 10 ^ {-7} مع الحساب لـ H_2. وتظهر توزيع التراكيز النسبية لـ CH على الخطوط المشاهدة في هذه الدراسة، باستثناء SgrB2 (M)، توزيعاً مثلثاً مع ذروة بين 5 و 7 كيلومتر. ويؤكد التشابه بين ملف التراكيز النسبية لـ H_2 الذي تم تحديده بالتالي وملف الغاز H_2 الخافي للـ CO الذي يتم تتبعه بواسطة الجزئية الباردة الطبيعية من إشعاع [CII] 158 ميكرون في المحور المجري، أكثر تأكيداً على استخدام CH كمشيط لـ H_2.
In this paper, we investigate the influence of hyperfine splitting on complex spectral lines, with the aim of evaluating canonical abundances by decomposing their dependence on hyperfine structures. This is achieved from first principles through deconvolution. We present high spectral resolution observations of the rotational ground state transitions of CH near 2 THz seen in absorption toward the strong FIR-continuum sources AGAL010.62$-$00.384, AGAL034.258+00.154, AGAL327.293$-$00.579, AGAL330.954$-$00.182, AGAL332.826$-$00.549, AGAL351.581$-$00.352 and SgrB2(M). These were observed with the GREAT instrument on board SOFIA. The observed line profiles of CH were deconvolved from the imprint left by the lines hyperfine structures using the Wiener filter deconvolution, an optimised kernel acting on direct deconvolution. The quantitative analysis of the deconvolved spectra first entails the computation of CH column densities. Reliable N(CH) values are of importance owing to the status of CH as a powerful tracer for H$_2$ in the diffuse regions of the interstellar medium. The N(OH)/N(CH) column density ratio is found to vary within an order of magnitude with values ranging from one to 10, for the individual sources that are located outside the Galactic centre. Using CH as a surrogate for H$_2$, we determined the abundance of the OH molecule to be X(OH)=1.09$times$10$^{-7}$ with respect to H$_2$. The radial distribution of CH column densities along the sightlines probed in this study, excluding SgrB2(M), showcase a dual peaked distribution peaking between 5 and 7 kpc. The similarity between the correspondingly derived column density profile of H$_2$ with that of the CO-dark H$_2$ gas traced by the cold neutral medium component of [CII] 158$~mu$m emission across the Galactic plane, further emphasises the use of CH as a tracer for H$_2$.
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