Publications – Page 6

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.

1 January 201431 January 2019

NGC 1266 as a Local Candidate for Rapid Cessation of Star Formation

g and r wide-field imaging of NGC 1266 taken as part of the MATLAS survey (Alatelo et al., 2014)

We present new Spectrographic Areal Unit for Research on Optical Nebulae (SAURON) integral-field spectroscopy and Swift Ultraviolet Optical Telescope (UVOT) observations of molecular outflow host galaxy NGC 1266 that indicate NGC 1266 has experienced a rapid cessation of star formation.

1 January 201331 January 2019

Discovery of a giant HI tail in the galaxy group HCG 44

H I contours overlaid on the g-band CFHT/MegaCam image (Serra et al., 2013)

We report the discovery of a giant HI tail in the intragroup medium of HCG 44 as part of the ATLAS^3D survey. The tail is ˜ 300 kpc long in projection and contains ˜ 5 × 10⁸ M_⊙ of HI. We detect no diffuse stellar light at the location of the tail down to ˜ 28.5 mag arcsec^{– 2} in g band.

27 May 201130 November 2021

The merger origin of a fast- and a slow-rotating early-type galaxy revealed with deep optical imaging

CFHT/MegaCam g-band surface brightness map of NGC 5557.

The final stages of mass assembly of present-day massive galaxies are expected to occur through the accretion of multiple satellites. Cosmological simulations thus predict a high frequency of stellar streams resulting from this mass accretion around the massive galaxies in the Local Volume. Such tidal streams are difficult to observe, especially in dense cluster environments, where they are readily destroyed. We present an investigation into the origins of a series of interlaced narrow filamentary stellar structures, loops and plumes in the vicinity of the Virgo Cluster, edge-on spiral galaxy, NGC 4216 that were previously identified by the Blackbird Telescope. Using the deeper, higher-resolution and precisely calibrated optical CFHT/MegaCam images obtained as part of the Next Generation Virgo Cluster Survey (NGVS), we confirm the previously identified features and identify a few additional structures.

1 July 20103 February 2019

A Collisional Origin for the Leo Ring

SImulated velocity map of the Leo Ring (Michel-Dansac et al., 2010)

Extended H I structures around galaxies are of prime importance for probing galaxy formation scenarios. The giant H I ring in the Leo group is one of the largest and most intriguing H I structures in the nearby universe. Whether it consists of primordial gas, as suggested by the apparent absence of any optical counterpart and the absence of an obvious physical connection to nearby galaxies, or of gas expelled from a galaxy in a collision is actively debated. We present deep wide field-of-view optical images of the ring region obtained with MegaCam on the CFHT.