Jafar
Aim of this website
The aim of this server is to enable people from the scientific community to easily identify and classify LSB
structures around galaxies in CFIS,MATLAS and NGVS images.
In particular, this website enables users to draw with precision the shapes of LSB
structures , overplotted on the images. This precise delimitation
of the structures will enable scientists to retrieve quantitative measurements about them,
which is a feature that is not possible on MATLAS website.
As explained in more details in the tutorial, for each galaxy, the user will
delimitate the boundary of each LSB structure as well as the galaxy,
the shape of its halo and its potential companion galaxy. Each shape drawn is then properly labeled.
Additional information such as the presence
of galactic cirrus or contaminants (like ghosted halos, satellite trails, high background) can be added.
Low Surface Brightness structures
The study of the morphology of galaxies is essential to constrain models of galaxy
evolution.
Indeed, in the standard model, galaxies are formed through successive mergers with galaxies and other
phenomena such as dark matter accretion or continuous process of cold gas.
Vestiges of these past interactions between galaxies remain today, and they are very important as their
shape and number informs us about the past merging history of a galaxy,
and may change its apparent morphology.
However, these structures, these collisional debris, are very faint so their detection is complicated.
They are called Low Surface Brightness (LSB) structures, as their flux per unit area is
low.
That is the reason why they have not been studied much outside the Local Group, until the use of powerful
enough telescopes made their studies possible.
In particular, the Canada-France-Hawaii Telescope (CFHT) provided deep enough images of
some galaxies
that were studied with the MATLAS survey: many LSB structures around elliptical galaxies
were discovered and classified. More recently, CFIS (Canada-France Imaging Suvey)
is a large CFHT program aiming at mapping a large part of the Northern hemisphere (5,000 square degrees)
with deep images, where MATLAS only performed pointed observations of galaxies.
CFIS images are interesting by their extended spatial coverage on the sky and their depth, making possible
the detection and classification of LSB structures
around a large number of galaxies.
