Papers by Natallia Lundqvist
Astronomy & Astrophysics, 2008
We have performed a deep optical imaging of 3C 58 SNR with the NOT in the B and V bands to detect... more We have performed a deep optical imaging of 3C 58 SNR with the NOT in the B and V bands to detect the optical counterpart of the associated pulsar J0295+6449 and its torus-like wind nebula visible in X-rays. We analyzed our data together with the archival data obtained with the Chandra in X-rays and with the Spitzer in the mid-IR. We detect a faint extended elliptical object with B=24.06 and V=23.11 whose peak brightness and center position are consistent at the sub-arcsecond level with the position of the pulsar. Its morphology and orientation are in excellent agreement with the torus-like pulsar nebula, seen almost edge on in X-rays although its extension is only about a half of that in X-rays. In the optical we likely see only the brightest central part of the torus with the pulsar. The object is identical to the counterpart of the torus recently detected in the mid-IR. The estimated pulsar contribution to the optical flux is less than 10%. Combinig the optical/mid-IR fluxes and X-ray power-law spectrum extracted from the spatial region constrained by the optical/IR source extent we compile a tentative multi-wavelength spectrum of the central part of the nebula. Within uncertainties of the interstellar extinction it is reminiscent of either the Crab or B0540-69 pulsar wind nebula spectra. The properties of the object strongly suggest it to be the optical counterpart of the 3C 58 pulsar + its wind nebula system, making 3C 58 the third member of such a class of the torus-like systems identified in the optical and mid-IR.
We present and discuss new visual wavelength-range observations of the inner regions of the super... more We present and discuss new visual wavelength-range observations of the inner regions of the supernova remnant SNR 0540-69.3 that is located in the Large Magellanic Cloud (LMC). These observations provide us with more spatial and spectral information than were previously available for this object. We use these data to create a detailed three-dimensional model of the remnant, assuming linear expansion of the ejecta. With the observations and the model we study the general three-dimensional structure of the remnant, and the influence of an active region in the remnant -a "blob" -that we address in previous papers. We used the fibrefed integral-field spectrograph VIMOS at the Very Large Telescope of the European Southern Observatory. The observations provide us with three-dimensional data in [O iii] λ5007 and [S ii] λλ6717, 6731 at an 0. ′′ 33×0. ′′ 33 spatial sampling and a velocity resolution of about 35 km s −1 . We decomposed the two, partially overlapping, sulphur lines and used them to calculate electron densities across the remnant at high signal-to-noise ratio. In our study we recover results of previous studies, but we are more importantly able to obtain more detailed information than before. Our analysis reveals a structure that stretches from the position of the "blob", and into the plane of the sky at a position angle of PA ≃ 60 • . Assuming a remnant age of 1000 years and the usual LMC distance, the structure has an inclination angle of about 65 • to the line of sight. The position angle is close to the symmetry axis with present and past activity in the visual and the X-ray wavelength ranges. We speculate that the pulsar is positioned along this activity axis, where it has a velocity along the line of sight of a few hundred km s −1 . The "blob" is most likely a region of shock activity, as it is mainly bright in [S ii]; future observations of [O ii] λλ3726, 3729 would be useful to test whether the S/O abundance ratio is higher than average for that location in the remnant. The striking resemblance in Xrays between the pulsar wind nebula (PWN) of SNR 0540-69.3 and the Crab, in combination with our findings in this paper, suggests that the symmetry axis is part of a torus in the PWN. This is in agreement with the original suggestion by Gotthelf & Wang.
Uploads
Papers by Natallia Lundqvist