Enhanced Doppler Beaming for Dust-enshrouded Objects and Pulsars in the Galactic Center
Abstract
Stars within the innermost part of the nuclear star cluster can reach orbital velocities up to a few percent of the light speed. As analyzed by Rafikov, Doppler boosting of stellar light may be of relevance at the pericenter of stellar orbits, especially with the upcoming high-precision photometry in the near- and mid-infrared bands. Here we analyze the previously neglected effect of the infrared spectral index of monitored objects on the Doppler-boosted continuum emission in a narrow photometric band. In contrast to main-sequence stars, the detected compact infrared-excess dust-enshrouded objects have an enhanced Doppler-boosting effect by as much as an order of magnitude, with the variability amplitude of the order of 10% for the most eccentric orbits. In a similar way, pulsars dominated by nonthermal synchrotron emission are also expected to exhibit a stronger Doppler-boosted signal by a factor of at least 4 in comparison with canonical S stars. In case the stellar orbit is robustly determined, the relative flux variation can thus provide hints about the nature of the objects. For extended dust-enshrouded objects, such as G1, that are variable due to tidal, ellipsoidal, bow-shock, and irradiation effects, the subtraction of the expected Doppler-boosting variations will help to better comprehend their internal physics. In addition, the relative flux variability due to higher-order relativistic effects is also modified for different negative spectral indices in a way that it can obtain both positive and negative values with the relative variability of the order of 1%.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 2021
- DOI:
- 10.3847/1538-4357/ac043a
- arXiv:
- arXiv:2105.11036
- Bibcode:
- 2021ApJ...915..111Z
- Keywords:
-
- Galactic center;
- Stellar photometry;
- Relativistic binary stars;
- 565;
- 1620;
- 1386;
- Astrophysics - High Energy Astrophysical Phenomena;
- Astrophysics - Instrumentation and Methods for Astrophysics;
- General Relativity and Quantum Cosmology
- E-Print:
- 9 pages, 5 figures, 1 table