Enhanced Doppler Beaming for Dust-enshrouded Objects and Pulsars in the Galactic Center
| Authors | |
|---|---|
| Year of publication | 2021 |
| Type | Article in Periodical |
| Magazine / Source | The Astrophysical Journal |
| MU Faculty or unit | |
| Citation | |
| Web | https://doi.org/10.3847/1538-4357/ac043a |
| Doi | http://dx.doi.org/10.3847/1538-4357/ac043a |
| Keywords | Galactic center; Stellar photometry; Relativistic binary stars |
| Description | 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%. |
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