http://mission.lam.fr/vestige/index.html Samuel Boissier, Laboratoire d'astrophysique de Marseille 1
The Team 2
Galaxies and gas in clusters Cluster environment: - high galaxy density (ρgal~ 100 gal Mpc-3) - high velocity dispersion (v ~ 1000 km s-1) - ICM: hot (T ~ 107-108 K) and dense (ρicm ~ 10-3 cm-3). Perturbing mechanisms: - starvation - galaxy harassment - ram pressure - thermal evaporation Questions: - Fraction of galaxies affected? - Dominant process? - Effect on star formation - Fate of stripped gas VIRGO cluster : UV : GUViCS (UV) Visible : NGVS FIR : HeViCS HI : ALFALFA + VIVA + ASKAP 4
VESTIGE : a CFHT Large Program Virgo Environmental Survey Tracing Ionised Gas Emission LP (2017-2019), MegaCam@CFHT (1ox1o) 50 nights allocated to cover the Virgo cluster within 1 virial radius (~ 104o2) Integration time: 2 h in the new Hα filter (λ = 6563 Å, Δλ = 106 Å; T = 93%), 12 min in r (for the stellar continuum subtraction) Sensitivity: f(hα) ~ 2x10-17 erg sec-1 cm-2 (5σ) for point sources Σ(Hα) ~ 2x10-18 erg sec-1 cm-2 arcsec-2 (1σ) at 3 arcsec resolution Median seeing 0.65 arcsec. (At he Virgo Cluster distance : 1 arcsec=80 pc) Elixir-LSB pointing strategy for sky background. Hα narrow band: Yagi et al 2010 ; Fossati et al 2012 ; Gavazzi et al 2001 ; Boselli & Gavazzi 2014 ; Yoshida et al 2002 ; Kenney et al 2008 ; Sun et al 5 2007 ; Zhang et al 2013
VESTIGE : a CFHT Large Program Virgo Environmental Survey Tracing Ionised Gas Emission VIRGO SCIENCE The effects of the environment on galaxy evolution The fate of the stripped gas in cluster galaxies The star forming process in nearby galaxies The ionised gas emission in early-type galaxies The Hα luminosity function of galaxies The Hα scaling relation in galaxies The nature of dark galaxies The dynamical structure of the Virgo cluster The HII luminosity function of cluster galaxies Planetary nebulae and the origin of the intracluster light FOREGROUND The diffuse ionised emission of the Milky Way SCIENCE High velocity clouds, compact sources and Galactic fountains BACKGROUND SCIENCE High redshift emission line galaxies (Lyα, [OII], [OIII]) 6 QSOs
Status 244 validated frames in the r-band (60 sec exposure) and 268 (600 sec) in the Hα, for a total of 54.42 hours (exp. time). data fully processed with Elixir-LSB. data fully reduced with MegaPipe (astrometric correction, photometric calibration and the stacking of the different frames). on-going optimisation of the pipeline for stellar continuum subtraction for sources of different color. verification of performances (sensitivity / seeing) Description of the survey in A Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE). I. Introduction to the Survey Boselli et al., in preparation 7
Filaments in M87 Gavazzi et al. 2000 1.2 arcsec seeing Wide Field Camera - INT Diffuse emission in early-type galaxies in Virgo, both in massive E and de Shocks in merging/interacting systems Diffuse emission from evolved stellar populations Residual star formation (core of recently formed de) Belfiore et al. 2016 Michielsen et al. 2004 Boselli et al. 2008 8
Star forming regions in NGC4254 UV GALEX ugr NGVS SF regions detected in FUV and NUV ; a few detection in u 9
Star forming regions in NGC4254 UV GALEX VESTIGE Hα Boselli et al 2017 Identification of resolved HII regions of luminosity down to 10^37 erg/s New Hα measurements to constrain star formation properties in outer regions 10 (IMF, stochasticity).
Ram Pressure Stripping In NGC4569 From pilot observations Boselli et al 2016 11
Ram Pressure Stripping In NGC4569 ionised gas mass in the tail = large fraction of stripped HI Ionisation in situ (not star formation) Very limited (if not 0) star formation linked to RPS (see also Boissier et al. 2012) Gas expelled by the nuclear outflow is ~ 1% that removed by ram pressure Boselli et al 2016 12
Ram Pressure Stripping In NGC4330 Chung et al 2007 Fossati et al 2017 13
http://mission.lam.fr/vestige/index.html Boselli et al. 2016 On going Large Program : Hα survey in the Virgo cluster First Results - Filaments and diffuse structures in E and de - Ionised Gaz in ram-pressure stripped systems - HII regions in outer regions of Virgo galaxies Stay tuned for more 14