Zhang, Shuo10; Hailey, Charles J.10; Baganoff, Frederick K.11; Bauer, Franz E.5; Boggs, Steven E.6; Craig, William W.6; Christensen, Finn Erland1; Gotthelf, Eric V.10; Harrison, Fiona A.12; Mori, Kaya10; Nynka, Melania10; Stern, Daniel8; Tomsick, John A.6; Zhang, William W.13
1 National Space Institute, Technical University of Denmark2 Astrophysics, National Space Institute, Technical University of Denmark3 Columbia University4 Massachusetts Institute of Technology5 Pontifícia Universidade Católica6 University of California7 California Institute of Technology8 NASA Jet Propulsion Laboratory9 NASA Goddard Space Flight Center10 Columbia University11 Massachusetts Institute of Technology12 California Institute of Technology13 NASA Goddard Space Flight Center
We report the first detection of high-energy X-ray (E > 10 keV) emission from the Galactic center non-thermal filament G359.89–0.08 (Sgr A–E) using data acquired with the Nuclear Spectroscopic Telescope Array (NuSTAR). The bright filament was detected up to ∼50 keV during a NuSTAR Galactic center monitoring campaign. The featureless power-law spectrum with a photon index Γ ≈ 2.3 confirms a non-thermal emission mechanism. The observed flux in the 3-79 keV band is FX = (2.0 ± 0.1) × 10–12 erg cm–2 s–1, corresponding to an unabsorbed X-ray luminosity LX = (2.6 ± 0.8) × 1034 erg s–1 assuming a distance of 8.0 kpc. Based on theoretical predictions and observations, we conclude that Sgr A–E is unlikely to be a pulsar wind nebula (PWN) or supernova remnant-molecular cloud (SNR-MC) interaction, as previously hypothesized. Instead, the emission could be due to a magnetic flux tube which traps TeV electrons. We propose two possible TeV electron sources: old PWNe (up to ∼100 kyr) with low surface brightness and radii up to ∼30 pc or MCs illuminated by cosmic rays (CRs) from CR accelerators such as SNRs or Sgr A*.