Publications – Page 4

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.

1 April 20163 September 2019

Using deep images and simulations to trace collisional debris around massive galaxies

Duc 2017. The classification scheme used for the MATLAS deep imaging survey

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.

1 July 201531 January 2021

Star formation in the outer regions of the early-type galaxy NGC 4203

Composite g′ + r′ MegaCam image of NGC 4203 with the dust lanes superimposed in red (Yildiz et al.2015)

NGC 4203 is a nearby early-type galaxy surrounded by a very large, low-column-density H I disc. In this paper, we study the star formation efficiency in the gas disc of NGC 4203 by using the UV, deep optical imaging and infrared data.

1 July 201531 January 2021

Applying galactic archeology to massive galaxies using deep imaging surveys

Collection of images from the MATLAS survey for a sample of ETGs (IAUS311)

Various programs aimed at exploring the still largely unknown low surface brightness Universe with deep imaging optical surveys have recently started. They open a new window for studies of galaxy evolution, pushing the technique of galactic archeology outside the Local Group (LG).

1 May 201527 June 2020

The stellar accretion origin of stellar population gradients in massive galaxies at large radii

Colour gradients (g − i, g − r and u − g, from left to right) at z = 2, 1, 0 (from top to bottom) for the 10 galaxies (different colours) in the MNoW and WM models (Hirschmann et al., 2015)

We investigate the evolution of stellar population gradients from z = 2 to 0 in massive galaxies at large radii (r > 2R_eff) using 10 cosmological zoom simulations of haloes with 6 × 10¹² M_⊙ < M_halo < 2 × 10¹³ M_⊙. The simulations follow metal cooling and enrichment from SNII, SNIa and asymptotic giant branch winds. We explore the differential impact of an empirical model for galactic winds that reproduces the mass-metallicity relation and its evolution with redshift.

1 January 20153 September 2019

The new look of early-type galaxies and surrounding fields disclosed by extremely deep optical images

Observing sequence of MATLAS observations (Duc et al., 2015)

Galactic archaeology based on star counts is instrumental to reconstruct the past mass assembly of Local Group galaxies. The development of new observing techniques and data reduction, coupled with the use of sensitive large field of view cameras, now allows us to pursue this technique in more distant galaxies exploiting their diffuse low surface brightness (LSB) light. As part of the ATLAS3D project, we have obtained with the MegaCam camera at the Canada-France-Hawaii Telescope extremely deep, multiband images of nearby early-type galaxies (ETGs).

1 December 201431 January 2019

Accretion-Inhibited Star Formation in the Warm Molecular Disk of the Green-valley Elliptical Galaxy NGC 3226?

HI emission superimposed on a deep optical image of the galaxy from MATLAS (Appleton et al., 2014)

We present archival Spitzer photometry and spectroscopy and Herschel photometry of the peculiar “Green Valley” elliptical galaxy NGC 3226. The galaxy, which contains a low-luminosity active galactic nucleus (AGN), forms a pair with NGC 3227 and is shown to lie in a complex web of stellar and H I filaments.

1 May 201431 January 2019

Identification of old tidal dwarfs near early-type galaxies from deep imaging and H I observations

Composite MegaCam images of the ETGs hosting TDG candidates (Duc et al., 2014)

It has recently been proposed that the dwarf spheroidal galaxies located in the Local Group discs of satellites (DoSs) may be tidal dwarf galaxies (TDGs) born in a major merger at least 5 Gyr ago. Whether TDGs can live that long is still poorly constrained by observations. As part of deep optical and H I surveys with the Canada-France-Hawaii Telescope (CFHT) MegaCam camera and Westerbork Synthesis Radio Telescope made within the ATLAS3D project, and follow-up spectroscopic observations with the Gemini-North telescope, we have discovered old TDG candidates around several early-type galaxies.