Related papers: Balmer-Dominated Shocks Revisited
In this paper we emphasize the non-Lorentzian behavior of the Balmer series in helium-dominated DBA white dwarf stars for which the decades-old problem exists for the determination of the hydrogen abundance. In a very recent work, we have…
We present spectroscopy of 28 SNR candidates as well as one H II region in M81, and two SNR candidates in M82. Twenty six out of the M81 candidates turn out to be genuine SNRs, and two in M82 may be shocked condensations in the galactic…
Emission mechanisms of the shell-type supernova remnant (SNR) RX J1713.7-3946 are studied with multi-wavelength observational data from radio, X-ray, GeV $\gamma$-ray to TeV $\gamma$-ray band. A Markov Chain Monte Carlo method is employed…
Supernova 1987A remains the most well-studied supernova to date. Observations produced excellent broad-band photometric and spectroscopic coverage over a wide wavelength range at all epochs. We model the observed spectra from Day 1 to Day…
One aspect of supernova remnant evolution that is relatively unstudied is the influence of an AGN environment. A high density ambient medium and a nearby powerful continuum source will assist the cooling of shocked ejecta and swept-up gas.…
We present new diagnostic tools for distinguishing supernova remnants (SNRs) from HII regions. Up to now, sources with flux ratio [S II]/H$\rm{\alpha}$ higher than 0.4 have been considered as SNRs. Here, we present the combinations of three…
We present an analysis of the dispersed spectral data from 11 epochs (March 2011 to September 2018) of supernova remnant (SNR) 1987A observations performed with Chandra. These observations were performed with the High Energy Transmission…
Supernova remnant (SNR) RX J1713.7-3946 is well known for its bright TeV gamma-ray emission with shell-like morphology. To constrain the hydrodynamical evolution, we have performed six times observations of the northwestern (NW) shell with…
With Spitzer IRS we have obtained sensitive low-resolution spectroscopy from 5 to 35 microns for six supernova remnants (SNRs) that show evidence of shocked molecular gas: Kes 69, 3C 396, Kes 17, G346.6-0.2, G348.5-0.0 and G349.7+0.2.…
We present results from an optical study of two young Balmer-dominated remnants of SNIa in the Large Magellanic Cloud, 0509$-$67.5 and 0519$-$69.0, in an attempt to search for signatures of efficient cosmic-ray (CR) acceleration. We combine…
The middle-aged supernova remnant (SNR) CTB 37A is known to interact with several dense molecular clouds through the detection of shocked ${\rm H_{2}}$ and OH 1720 MHz maser emission. In the present work, we use eight years of $\textit…
We report the first detection of optical emission from the shell-type Galactic supernova remnant (SNR) G108.2$-$0.6. We obtained H$\alpha$ images and long-slit spectra using the 1.5-m RTT150 telescope to examine the morphological and…
We present a time-dependent cosmic-ray modified shock model for which the calculated H-alpha emissivity profile agrees well with the H-alpha flux increase ahead of the Balmer-dominated shock at knot g in Tycho's supernova remnant, observed…
Estimating the cosmic-ray acceleration efficiency $ \epsilon $ in supernova remnants (SNRs) through observations is a challenging task in general. Based on the Rankine-Hugoniot shock conditions, we find an anticorrelation between $ \epsilon…
The presence of neutral hydrogen in the shock proximity changes the structure of the shock and affects the spectra of particles accelerated through the first-order Fermi mechanism. This phenomenon has profound implications for the…
Recent gamma-ray observations show that middle aged supernova remnants (SNRs) interacting with molecular clouds (MCs) can be sources of both GeV and TeV emission. Based on the MC association, two scenarios have been proposed to explain the…
Precise measurements of galactic cosmic rays revealed a significant difference between the rigidity spectral indices of protons and helium ions. This finding is a notable contrast to the commonly accepted theoretical prediction that…
We present integral-field spectroscopic observations with the VIMOS-IFU at the VLT of fast (2000-3000 km/s) Balmer-dominated shocks surrounding the northwestern rim of the remnant of supernova 1006. The high spatial and spectral resolution…
Supernova remnants (SNRs) are believed to be the major contributors to Galactic cosmic rays. The detection of non-thermal emission from SNRs demonstrates the presence of energetic particles, but direct signatures of protons and other ions…
We investigate the molecular environment of the supernova remnant (SNR) Kesteven 67 (G18.8+0.3) using observations in $^{12}$CO, $^{13}$CO, HCO$^+$,and HCN lines and possible associated $\gamma$-ray emission using 16-yr Fermi-LAT…