First detection of the 448 GHz H2O transition in space

• Autor(a) principal: Pereira-Santaella, Miguel
• Data de Publicação: 2017
• Outros Autores: González-Alfonso, Eduardo, Usero, Antonio, Garcia-Burillo, Santiago, Martín-Pintado, Jesús M., Colina, Luis, Alonso-Herrero, Almudena, Arribas, Santiago, Cazzoli, Sara, Rico Villas, Fernando, Rigopoulou, Dimitra, Storchi-Bergmann, Thaisa
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UFRGS
• Texto Completo: http://hdl.handle.net/10183/181151
• topic: Infravermelho; Nucleo galatico; Água; Meio interestelar; Galaxies: ISM; Galaxies: nuclei; Infrared: galaxies; ISM: molecules

We present the first detection of the ortho-H2O 423330 transition at 448 GHz in space. We observed this transition in the local (z = 0:010) luminous infrared (IR) galaxy ESO 320-G030 (IRAS F11506-3851) using the Atacama Large Millimeter/submillimeter Array (ALMA). The water 423330 emission, which originates in the highly obscured nucleus of this galaxy, is spatially resolved over a region of 65 pc in diameter and shows a regular rotation pattern compatible with the global molecular and ionized gas kinematics. The line profile is symmetric and well fitted by a Gaussian with an integrated flux of 37.0 0.7 Jy km s1. Models predict this water transition as a potential collisionally excited maser transition. On the contrary, in this galaxy, we find that the 423330 emission is primarily excited by the intense far-IR radiation field present in its nucleus. According to our modeling, this transition is a probe of deeply buried galaxy nuclei thanks to the high dust optical depths ( 100 m > 1, NH > 1024 cm2) required to e ciently excite it.