a deep imaging survey of massive galaxies and their surroundings
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
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.
Continue reading “A deconvolution technique to correct deep images of galaxies from instrumental scattered light”
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.
Continue reading “Globular Clusters as Tracers of Fine Structure in the Dramatic Shell Galaxy NGC 474”
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.
Continue reading “Probing interstellar turbulence in cirrus with deep optical imaging: no sign of energy dissipation at 0.01 pc scale”
Deep imaging programs, such as MATLAS which has just been completed at the CFHT, allows us to study with their diffuse light the outer stellar populations around large number of galaxies. We have carried out a systematic census of their fine structures, i.e. the collisional debris from past mergers.
Continue reading “Using deep images and simulations to trace collisional debris around massive galaxies”