Radio Synchrotron Emission from the Bow Shock of G2

Abstract

The radio flux from the synchrotron emission of electrons accelerated in the forward bow shock of G2 is expected to peak when the forward shock passes pericenter, possibly 7 to 9 months before the center of mass of G2 reaches pericenter ~3x10^15 cm from the Galactic Center (Narayan et al. 2012; Sadowski et al. 2013a,b). In this letter, we calculate the radio emission from the forward and reverse shock if G2 is a momentum-supported bow shock of a faint star with a high mass-loss rate as suggested by Scoville & Burkert (2013); Ballone et al. (2013). We show that the radio flux lies well below the quiescent radio flux of Sgr A* and will be difficult to detect. By contrast, in the cloud model of G2, the radio flux of the forward shock is predicted to be much larger than the quiescent radio flux and therefore should have already been detected (Narayan et al. 2012; Sadowski et al. 2013b). Therefore, radio measurements can reveal the nature of G2 well before G2 completes its periapsis passage.

[v2] Fixed citations, updated abstract. 3 figures. Submitted to MNRAS, accepted 2013 September 06. Received 2013 September 06; in original form 2013 August 02

References in corpus (4)

• Dissecting X-ray-emitting Gas around the Center of our Galaxy
• Keck Observations of the Galactic Center Source G2: Gas Cloud or Star?
• Pericenter passage of the gas cloud G2 in the Galactic Center
• Location of the bow shock ahead of cloud G2 at the Galactic Center

Cited by in corpus (15)

• Hot Accretion Flows Around Black Holes
• Radio and Millimeter Monitoring of Sgr A*: Spectrum, Variability, and Constraints on the G2 Encounter
• Monitoring the Dusty S-Cluster Object (DSO/G2) on its Orbit towards the Galactic Center Black Hole
• The Properties and Fate of the Galactic Center G2 Cloud
• Nature of the Galactic centre NIR-excess sources. I. What can we learn from the continuum observations of the DSO/G2 source?
• A Stellar Wind Origin for the G2 Cloud: Three-Dimensional Numerical Simulations
• Effect of an isotropic outflow from the Galactic centre on the bow-shock evolution along the orbit
• Constraining the accretion flow density profile near Sgr A* using the $L^{\prime }$-band emission of the S2 star
• Monitoring the Galactic Centre with Australia Telescope Compact Array
• Detecting Stars at the Galactic Centre via Synchrotron Emission
• 3D AMR hydrosimulations of a compact source scenario for the Galactic Centre cloud G2
• Probing the Gas Density in our Galactic Center: Moving Mesh Simulations of G2
• Simulating the pericentre passage of the Galactic centre star S2
• The Galactic Center Black Hole Laboratory
• The gas streamer G1-2-3 in the Galactic Center