H<i>α</i>3: an H<i>α</i>imaging survey of HI selected galaxies from ALFALFA

Gavazzi, G.; Savorgnan, Giulia; Fossati, M.; Dotti, Massimo; Fumagalli, Michele; Boselli, A.; Gutiérrez, L.; Toledo, Hector Hernández; Giovanelli, Riccardo; Haynes, Martha P.

doi:10.1051/0004-6361/201220916

Cited by 54 publications

(66 citation statements)

References 79 publications

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“…As a test we independently derive the rotational velocity from the baryonic TullyFisher relation presented by Lelli et al (2016). Using a stellar mass of 10 9.8 M and the HI mass-to-stellar mass scaling relation from Gavazzi et al (2013), we estimate a total baryonic mass M b = 10 10.02 M , which in turn implies a maximum rotational velocity of 123 km s −1 , in good agreement with the measured value from HI data.…”

Section: Unperturbed and Quenched Star Formation Historiessupporting

confidence: 61%

A Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE)

Fossati

Mendel

Boselli

et al. 2018

A&A

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151

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The Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE) is a blind narrow-band Hα+ [NII] imaging survey carried out with MegaCam at the Canada-France-Hawaii Telescope. During pilot observations taken in the spring of 2016 we observed NGC 4330, an intermediate mass (M * 10 9.8 M ) edge-on star forming spiral currently falling into the core of the Virgo cluster. While previous Hα observations showed a clumpy complex of ionised gas knots outside the galaxy disc, new deep observations revealed a low surface brightness ∼ 10 kpc tail exhibiting a peculiar filamentary structure. The filaments are remarkably parallel to one another and clearly indicate the direction of motion of the galaxy in the Virgo potential. Motivated by the detection of these features which indicate ongoing gas stripping, we collected literature photometry in 15 bands from the far-UV to the far-IR and deep optical long-slit spectroscopy using the FORS2 instrument at the ESO Very Large Telescope. Using a newly developed Monte Carlo code that jointly fits spectroscopy and photometry, we reconstructed the star formation histories in apertures along the major axis of the galaxy. Our results have been validated against the output of CIGALE, a fitting code which has been previously used for similar studies. We found a clear outside-in gradient with radius of the time when the quenching event started: the outermost radii were stripped ∼ 500 Myr ago, while the stripping reached the inner 5 kpc from the centre in the last 100 Myr. Regions at even smaller radii are currently still forming stars fueled by the presence of HI and H 2 gas. When compared to statistical studies of the quenching timescales in the local Universe we find that ram pressure stripping of the cold gas is an effective mechanism to reduce the transformation times for galaxies falling into massive clusters. Future systematic studies of all the active galaxies observed by VESTIGE in the Virgo cluster will extend these results to a robust statistical framework.

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Section: Unperturbed and Quenched Star Formation Historiessupporting

confidence: 61%

A Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE)

Fossati

Mendel

Boselli

et al. 2018

A&A

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151

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“…The galaxies mostly devoid of gas are the red early-type systems forming the red sequence. Gavazzi et al (2003aGavazzi et al ( , 2013b have also shown that this sequence in colors or gas fraction is also related to the mean density of the environment where galaxies reside, with redder colors and gas-poor systems dominating high-density regions (see Fig. 9).…”

Section: Gas Contentmentioning

confidence: 88%

On the origin of the faint-end of the red sequence in high-density environments

Boselli

Gavazzi

2014

Astron Astrophys Rev

155

125

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With the advent of the next generation wide-field cameras it became possible to survey in an unbiased mode galaxies spanning a variety of local densities, from the core of rich clusters, to compact and loose groups, down to filaments and voids. The sensitivity reached by these instruments allowed to extend the observation to dwarf galaxies, the most "fragile" objects in the universe. At the same time models and simulations have been tailored to quantify the different effects of the environment on the evolution of galaxies. Simulations, models, and observations consistently indicate that star-forming dwarf galaxies entering high-density environments for the first time can be rapidly stripped from their interstellar medium. The lack of gas quenches the activity of star formation, producing on timescales of ∼1 Gyr quiescent galaxies with spectro-photometric, chemical, structural, and kinematical properties similar to those observed in dwarf early-type galaxies inhabiting rich clusters and loose groups. Simulations and observations consistently identify ram pressure stripping as the major effect responsible for the quenching of the star-formation activity in rich clusters. Gravitational interactions (galaxy harassment) can also be important in groups or in clusters whenever galaxies have been members since early epochs. The observation of clusters at different redshifts combined with the present high infalling rate of galaxies onto clusters indicate that the quenching of the star-formation activity in dwarf systems and the formation of the faint end of the red sequence is a very recent phenomenon.

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“…First, Hα λ6563 and the [NII] doublet λλ 6548, 6584 are not spectrally resolved by means of narrow band interferential filters. We do know the line ratios for a large number of objects from integrated drift-scan spectroscopy (Gavazzi et al 2004;Boselli et al 2013), although they A91, page 6 of 15 are of limited use for our purpose, since line ratios almost certainly vary with the position in the galaxy (Genzel et al 2008;Yuan et al 2011). Therefore we did not apply any mean correction.…”

Section: Size Measurementsmentioning

confidence: 99%

Hα3: an Hαimaging survey of HI selected galaxies from ALFALFA

Fossati

Gavazzi

Savorgnan

et al. 2013

A&A

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Context. We present the analysis of the galaxy structural parameters from Hα3, an Hα narrow-band imaging follow-up survey of ∼800 galaxies selected from the HI Arecibo Legacy Fast ALFA Survey (ALFALFA) in the Local supercluster, including the Virgo cluster, and in the Coma supercluster. Aims. Taking advantage of Hα3, which provides the complete census of the recent star-forming, HI-rich galaxies in the local universe, we aim to investigate the structural parameters of the young (<10 Myr) and the old (>1 Gyr) stellar populations. By comparing the sizes of these stellar components, we investigated the spatial scale on which galaxies are growing at the present cosmological epoch and the role of the environment in quenching the star-formation activity. Methods. We computed the concentration, asymmetry, and clumpiness (CAS) structural parameters for recently born and old stars. To quantify the sizes we computed half-light radii and a new parameter dubbed EW/r based on the half-light radius of the Hα equivalent width map. To highlight the environmental perturbation, we adopt an updated calibration of the HI-deficiency parameter (De f HI ) that we use to divide the sample in unperturbed galaxies (De f HI ≤ 0.3) and perturbed galaxies (De f HI > 0.3). Results. The concentration index computed in the r band depends on the stellar mass and on the Hubble type these variables are related because most massive galaxies are bulge dominated therefore highly concentrated. Going toward later spirals and irregulars the concentration index and the mass decrease along with the bulge-to-disk ratio. Blue compact dwarfs (BCDs) are an exception because they have similar mass, but they are more concentrated than dwarf irregulars. The asymmetry and the clumpiness increase along the spiral sequence up to Sc-Sd, but they decrease going in the dwarf regime, where the light distribution is smooth and more symmetric. When measured on Hα images, the CAS parameters show no obvious correlations with Hubble type. Irrespective of whether we used the ratio between effective radii or the EW/r parameter, we found that the concentration index is the main parameter that describes the current growth of isolated galaxies but, for a fixed concentration, the stellar mass plays a second-order role. At the present epoch, massive galaxies are growing inside-out, conversely, the dwarfs are growing on the scale of their already assembled mass.

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Hα3: an Hαimaging survey of HI selected galaxies from ALFALFA

Cited by 54 publications

References 79 publications

A Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE)

A Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE)

On the origin of the faint-end of the red sequence in high-density environments

Hα3: an Hαimaging survey of HI selected galaxies from ALFALFA

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