The Intrinsic Two-dimensional Size of Sagittarius A*
Abstract
We report the detection of the two-dimensional structure of the radio source associated with the Galactic Center black hole, Sagittarius A*, obtained from Very Long Baseline Array observations at a wavelength of 7 mm. The intrinsic source is modeled as an elliptical Gaussian with major-axis size 35.4 × 12.6 RS in position angle 95° east of north. This morphology can be interpreted in the context of both jet and accretion disk models for the radio emission. There is supporting evidence in large angular-scale multi-wavelength observations for both source models for a preferred axis near 95°. We also place a maximum peak-to-peak change of 15% in the intrinsic major-axis size over five different epochs. Three observations were triggered by detection of near infrared (NIR) flares and one was simultaneous with a large X-ray flare detected by NuSTAR. The absence of simultaneous and quasi-simultaneous flares indicates that not all high energy events produce variability at radio wavelengths. This supports the conclusion that NIR and X-ray flares are primarily due to electron excitation and not to an enhanced accretion rate onto the black hole.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 2014
- DOI:
- 10.1088/0004-637X/790/1/1
- arXiv:
- arXiv:1405.1456
- Bibcode:
- 2014ApJ...790....1B
- Keywords:
-
- accretion;
- accretion disks;
- galaxies: active;
- galaxies: jets;
- Galaxy: center;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- accepted for publication in ApJ