Thomas B. Martin | Searcharxiv

arXiv2017

A SITELLE view of M31's central region - I: Calibrations and radial velocity catalogue of nearly 800 emission-line point-like sources

We present a detailed description of the wavelength, astrometric and photometric calibration plan for SITELLE, the imaging Fourier transform spectrometer attached to the Canada-France-Hawaii telescope, based on observations of a red (647 - 685 nm) data cube of the central region (11$' \times 11'$) of the Andromeda galaxy. The first application, presented in this paper, is a radial-velocity catalogue (with uncertainties of $\sim 2 - 6$ km/s) of nearly 800 emission-line point-like sources, including $\sim$ 450 new discoveries. Most of the sources are likely planetary nebulae, although we also detect five novae (having erupted in the first 8 months of 2016) and one new supernova remnant candidate.

astro-ph.GA↗

arXiv2016

Optimal fitting of gaussian-apodized or under-resolved emission lines in Fourier Transform spectra providing new insights on the velocity structure of NGC 6720

An analysis of the kinematics of NGC 6720 is performed on the commissioning data obtained with SITELLE, the Canada-France-Hawaii Telescope's new imaging Fourier transform spectrometer. In order to measure carefully the small broadening effect of a shell expansion on an unresolved emission line, we have determined a computationally robust implementation of the convolution of a Gaussian with a sinc instrumental line shape which avoids arithmetic overflows. This model can be used to measure line broadening of typically a few km/s even at low spectral resolution (R less than 5000). We have also designed the corresponding set of Gaussian apodizing functions that are now used by ORBS, the SITELLE's reduction pipeline. We have implemented this model in ORCS, a fitting engine for SITELLE's data, and used it to derive the [SII] density map of the central part of the nebula. The study of the broadening of the [NII] lines shows that the Main Ring and the Central Lobe are two different shells with different expansion velocities. We have also derived deep and spatially resolved velocity maps of the Halo in [NII] and Halpha and found that the brightest bubbles are originating from two bipolar structures with a velocity difference of more than 35 km/s lying at the poles of a possibly unique Halo shell expanding at a velocity of more than 15 km/s.

astro-ph.GA↗