matlas – Page 7

5 January 201931 January 2019

Une vision fine des cirrus galactiques

En combinant des observations multi-longueur d’ondes obtenues depuis l’espace avec les satellites Planck et WISE et au sol avec le CFHT, une équipe de chercheurs notamment du CNRS et du CEA est parvenu à sonder la structure de la matière interstellaire avec une finesse inégalée. L’étude a en particulier permis de déterminer les propriétés de la turbulence interstellaire sur une gamme d’échelles spatiales encore jamais atteinte: de 10 pc à 0.01 pc. L’innovation principale de ces travaux est l’utilisation d’un télescope optique (le CFHT) pour étudier la structure de la matière à très grande résolution spatiale, ce que ne permettent pas les observations classiques du milieu interstellaire effectuées dans l’infrarouge. Ces travaux sont publiés dans la revue Astronomy and Astrophysics.

27 September 201810 February 2019

Protected: Ultra Diffuse Galaxies with an Excess of Globular Clusters

1 March 201810 February 2019

Protected: Exploring the low surface brightness universe

1 March 20183 February 2019

Revisiting Stephan’s Quintet with deep optical images (associated paper)

MegaCam true color image image of the Stephan’s Quintet (Duc et al., 2018)

Stephan’s Quintet, a compact group of galaxies, is often used as a laboratory to study a number of phenomena, including physical processes in the interstellar medium, star formation, galaxy evolution, and the formation of fossil groups. As such, it has been subject to intensive multiwavelength observation campaigns. Yet, models lack constrains to pin down the role of each galaxy in the assembly of the group. We revisit here this system with multiband deep optical images obtained with MegaCam on the Canada-France-Hawaii Telescope (CFHT), focusing on the detection of low surface brightness (LSB) structures.

1 January 20184 September 2019

Image release: Stephan’s Quintet

The field around NGC 7331 and the Stephan’s Quintet, as seen by MegaCam. The true color composite image reveals multiple foreground and background structures, such as Milky-Way cirrus emission, extended stellar halos around the galaxies and tidal debris of past collisions.
The image was obtained with the same procedure as for the MATALS survey; it was originally aimed at being published in the CFHT yearly calendar.
Published in Duc et al 2018

1 May 201731 January 2019

A deconvolution technique to correct deep images of galaxies from instrumental scattered light

Deep imaging of the diffuse light that is emitted by stellar fine structures and outer halos around galaxies is often now used to probe their past mass assembly. Because the extended halos survive longer than the relatively fragile tidal features, they trace more ancient mergers. We use images that reach surface brightness limits as low as 28.5-29 mag arcsec^-2 (g-band) to obtain light and color profiles up to 5-10 effective radii of a sample of nearby early-type galaxies.

1 February 201731 January 2019

Globular Clusters as Tracers of Fine Structure in the Dramatic Shell Galaxy NGC 474

Globular clusters (GCs) are some of the most visible tracers of the merging and accretion histories of galaxy halos. Metal-poor GCs, in particular, are thought to arrive in massive galaxies largely through dry, minor merging events, but it is rare to see a direct connection between GCs and visible stellar streams. NGC 474 is a post-merger early-type galaxy with dramatic fine structures made of concentric shells and radial streams that have been more clearly revealed by deep imaging. We present a study of GCs in NGC 474 to better establish the relationship between merger-induced fine structure and the GC system.

20 July 201631 January 2019

Probing interstellar turbulence in cirrus with deep optical imaging: no sign of energy dissipation at 0.01 pc scale

Diffuse Galactic light has been observed in the optical since the 1930s. We propose that, when observed in the optical with deep imaging surveys, it can be used as a tracer of the turbulent cascade in the diffuse interstellar medium (ISM), down to scales of about 1 arcsec. Here we present a power spectrum analysis of the dust column density of a diffuse cirrus at high Galactic latitude (l ~ 198 deg, b ~ 32 deg) as derived from the combination of a MegaCam g-band image, obtained as part of the MATLAS large programme at the CFHT, with Planck radiance and Wise 12 micron data.