Balmer Filaments in Tycho’s Supernova Remnant: An Interplay between Cosmic-ray and Broad-neutral Precursors

Journal Article · Sun Sep 10 04:00:00 EDT 2017 · Astrophysical Journal

DOI:https://doi.org/10.3847/1538-4357/AA8323· OSTI ID:22875665

Knežević, Sladjana ^[1]; Läsker, Ronald ^[2]; Van de Ven, Glenn; Bailer-Jones, Coryn A. L. ^[3]; Font, Joan; Beckman, John ^[4]; Raymond, John C. ^[5]; Morlino, Giovanni ^[6]; Ghavamian, Parviz ^[7]; Hughes, John P. ^[8]; Heng, Kevin ^[9]

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1. Department of Particle Physics and Astrophysics, Faculty of Physics, The Weizmann Institute of Science, P.O. Box 26, Rehovot 76100 (Israel)
2. Finnish Centre for Astronomy with ESO (FINCA), University of Turku, Väisäläntie 20, FI-21500 Kaarina (Finland)
3. Max Planck Institute for Astronomy, Königstuhl 17, D-69117, Heidelberg (Germany)
4. Instituto de Astrofísica de Canarias, Vía Láctea, La Laguna, Tenerife (Spain)
5. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
6. INFN Gran Sasso Science Institute, viale F. Crispi 7, I-67100 L’Aquila (Italy)
7. Department of Physics, Astronomy and Geosciences Towson University, Towson, MD 21252 (United States)
8. Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States)
9. University of Bern, Center for Space and Habitability, Sidlerstrasse 5, CH-3012, Bern (Switzerland)

We present Hα spectroscopic observations and detailed modeling of the Balmer filaments in the supernova remnant (SNR) Tycho (SN 1572). We used GH α FaS (Galaxy Hα Fabry–Pérot Spectrometer) on the William Herschel Telescope with a 3.′4 × 3.′4 field of view, 0.″2 pixel scale, and σ{sub instr}=8.1 km s{sup −1} resolution at 1″ seeing for ∼10 hr, resulting in 82 spatial−spectral bins that resolve the narrow Hα line in the entire SN 1572 northeastern rim. For the first time, we can therefore mitigate artificial line broadening from unresolved differential motion and probe Hα emission parameters in varying shock and ambient medium conditions. Broad Hα line remains unresolved within spectral coverage of 392 km s{sup −1}. We employed Bayesian inference to obtain reliable parameter confidence intervals and to quantify the evidence for models with multiple line components. The median Hα narrow-line (NL) FWHM of all bins and models is W{sub NL}=(54.8±1.8) km s{sup −1} at the 95% confidence level, varying within [35, 72] km s{sup −1} between bins and clearly broadened compared to the intrinsic (thermal) ≈20 km s{sup −1}. Possible line splits are accounted for, significant in ≈18% of the filament, and presumably due to remaining projection effects. We also find widespread evidence for intermediate-line emission of a broad-neutral precursor, with a median W{sub IL}=(180±14) km s{sup −1} (95% confidence). Finally, we present a measurement of the remnant’s systemic velocity, V{sub LSR}=−34 km s{sup −1}, and map differential line-of-sight motions. Our results confirm the existence and interplay of shock precursors in Tycho’s remnant. In particular, we show that suprathermal NL emission is near-universal in SN 1572, and that, in the absence of an alternative explanation, collisionless SNR shocks constitute a viable acceleration source for Galactic TeV cosmic-ray protons.

• OSTI ID: 22875665
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 846; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ACCELERATION
COMPARATIVE EVALUATIONS
COMPUTERIZED SIMULATION
COSMIC RADIATION
EMISSION
GALAXIES
LINE BROADENING
PROTONS
RESOLUTION
SHOCK WAVES
SUPERNOVA REMNANTS
TELESCOPES
TEV RANGE
VELOCITY