Sgr A* and Its Environment: Low-mass Star Formation, the Origin of X-Ray Gas and Collimated Outflow
We present high-resolution multiwavelength radio continuum images of the region within 150″ of Sgr A∗, revealing a number of new extended features and stellar sources in this region. First, we detect a continuous 2″ east-west ridge of radio emission, linking Sgr A∗ and a cluster of stars associated...
| Autores: | , , , , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión aceptada para publicación |
| Fecha de publicación: | 2016 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/381478 |
| Acceso en línea: | http://hdl.handle.net/10261/381478 |
| Access Level: | acceso abierto |
| Palabra clave: | Accretion, accretion disks Black hole physics Galaxy: center |
| Sumario: | We present high-resolution multiwavelength radio continuum images of the region within 150″ of Sgr A∗, revealing a number of new extended features and stellar sources in this region. First, we detect a continuous 2″ east-west ridge of radio emission, linking Sgr A∗ and a cluster of stars associated with IRS 13 N and IRS 13E. The ridge suggests that an outflow of east-west blob-like structures is emerging from Sgr A∗. In particular, we find arc-like radio structures within the ridge with morphologies suggestive of photoevaporative protoplanetary disks. We use infrared K and L′ fluxes to show that the emission has similar characteristics to those of a protoplanetary disk irradiated by the intense radiation field at the Galactic center. This suggests that star formation has taken place within the S-cluster 2″ from Sgr A∗. We suggest that the diffuse X-ray emission associated with Sgr A∗ is due to an expanding hot wind produced by the mass loss from B-type main sequence stars, and/or the disks of photoevaporation of low mass young stellar objects (YSOs) at a rate of ∼10 M yr. The proposed model naturally reduces the inferred accretion rate and is an alternative to the inflow-outflow style models to explain the underluminous nature of Sgr A∗. Second, on a scale of 5″ from Sgr A∗, we detect new cometary radio and infrared sources at a position angle PA ∼ 50° which is similar to that of two other cometary sources X3 and X7, all of which face Sgr A∗. In addition, we detect a striking tower of radio emission at a PA ∼ 50°-60° along the major axis of the Sgr A East supernova remnant shell on a scale of 150″ from Sgr A∗. We suggest that the cometary sources and the tower feature are tracing interaction sites of a mildly relativistic jet from Sgr A∗ with the atmosphere of stars and the nonthermal Sgr A East shell at a PA ∼ 50°-60° with , and opening angle 10°. Lastly, we suggest that the east-west ridge of radio emission traces an outflow that is potentially associated with past flaring activity from Sgr A∗. The position angle of the outflow driven by flaring activity is close to -90°. © 2016. The American Astronomical Society. All rights reserved. |
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