arXiv subjects

L. Koch Miramond

Publications and source records attributed to L. Koch Miramond.

3 recordsLinked to original sources

arXiv2012

Infrared imaging and polarimetric observations of the pulsar wind nebula in SNR G21.5-0.9

We present infrared observations of the supernova remnant G21.5-0.9 with the Very Large Telescope, the Canada-France-Hawaii Telescope and the Spitzer Space Telescope. Using the VLT/ISAAC camera equipped with a narrow-band [FeII] 1.64um filter the entire pulsar wind nebula in SNR G21.5-0.9 was imaged. This led to detection of iron line-emitting material in the shape of a broken ring-like structure following the nebula's edge. The detected emission is limb-brightened. We also detect the compact nebula surrounding PSR J1833-1034, both through imaging with the CFHT/AOB-KIR instrument (K' band) and the IRAC camera (all bands) and also through polarimetric observations performed with VLT/ISAAC (Ks band). The emission from the compact nebula is highly polarised with an average value of the linear polarisation fraction $P_{L}^{avg} \simeq 0.47$, and the swing of the electric vector across the nebula can be observed. The infrared spectrum of the compact nebula can be described as a power law of index $α_{IR} = 0.7 \pm 0.3$, and suggests that the spectrum flattens between the infrared and X-ray bands.

astro-ph.GA↗

arXiv2005

SS 433 : a phenomenon imitating a Wolf-Rayet star

We present mid-infrared (2-12 micron) spectra of the microquasar SS 433 obtained with the Infrared Space Observatory (spectroscopic mode of ISOPHOT and ISOCAM). We compare them to the spectra of four Wolf-Rayet stars: WR78, WR134, WR136, and WR147 in the same wavelength range. The mid-infrared spectrum of SS 433 mainly shows HI and HeI emission lines and is very similar to the spectrum of WR147, a WN8(h)+B0.5V binary. The 2-12 micron continuum emission of SS 433 corresponds to optically thin and partially optically thick free-free emission, from which we calculate a mass loss rate of 2-3 x 10^{-4} Msun/yr if the wind is homogeneous and a third of these values if it is clumped. This is consistent with a strong stellar wind from a WN star. However, following recent studies concluding that the mass donor star of SS 433 is not a Wolf-Rayet star, we propose that this strong wind out flows from a geometrically thick envelope of material that surrounds the compact object like a stellar atmosphere, imitating the Wolf-Rayet phenomenon. This wind could also wrap the mass donor star, and at larger distances (~ 40 AU), it might form a dust envelope from which the thermal emission, detected with ISOPHOT at 25 micron and 60 micron, would originate. This wind also probably feeds the material that is ejected in the orbital plane of the binary system and that forms the equatorial outflow detected in radio at distances > 100 AU.

astro-ph↗

arXiv2004

SS 433: a WR X-ray binary or a WR-type phenomenon ?

We present mid-infrared spectra of the microquasar SS 433 obtained with the Infrared Space Observatory (spectroscopic mode of ISOPHOT) and compare them to the spectra of four Wolf-Rayet stars. The mid-infrared spectrum of SS 433 shows mainly HI and HeI emission lines and is very similar to the spectrum of WR 147, a WN8(h)+B0.5V binary with a colliding wind. The 2-12 micron continuum emission corresponds to optically thin and partially optically thick free-free emission from which we calculate a mass loss rate of 1.4-2.2x10^{-4} M_sun/yr if the wind is homogeneous and a third of these values if it is clumped, which is consistent with a strong WN stellar wind. We propose that this strong wind outflows from a geometrically thick envelope of material surrounding the compact object like a stellar atmosphere, imitating the Wolf-Rayet phenomenon.

astro-ph↗