The H<i>α</i> Galaxy Survey

James, P. A.; Shane, N.; Knapen, Johan H.; Etherton, J.; Percival, S. M.

doi:10.1051/0004-6361:20035892

Cited by 47 publications

(45 citation statements)

References 56 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The [NII] flux could originate from stellar photoionisation powered by young high-mass OB stars, or from other physical processes, such as shock heating or photoionisation with a power-law spectrum (see e.g. discussion in James et al 2005). The central supermassive black hole in NGC 4371 -with a mass determined via dynamical modelling (P. Erwin et al, in prep.)…”

Section: Environmental Effects: the Lack Of Gas And Recent Star Formamentioning

confidence: 99%

MUSE tells the story of NGC 4371: The dawning of secular evolution

Gadotti¹,

Seidel²,

Sánchez‐Blázquez³

et al. 2015

A&A

134

View full text Add to dashboard Cite

We use data from the Multi-Unit Spectroscopic Explorer (MUSE), recently commissioned at the Very Large Telescope (VLT), to study the kinematics and stellar population content of NGC 4371, an early-type massive barred galaxy in the core of the Virgo cluster. We integrate this study with a detailed structural analysis using imaging data from the Hubble and Spitzer Space Telescopes, which allows us to perform a thorough investigation of the physical properties of the galaxy. We show that the rotationally supported inner components in NGC 4371, i.e. an inner disc and a nuclear ring -which, according to the predominant scenario, are built with stars formed from gas brought to the inner region by the bar -are vastly dominated by stars older than 10 Gyr. Our results thus indicate that the formation of the bar occurred at a redshift of about z = 1.8 +0.5 −0.4 (error bars are derived from 100 Monte Carlo realisations). NGC 4371 thus testifies to the robustness of bars. In addition, the mean stellar age of the portion of the major disc of the galaxy that is covered by our MUSE data is above 7 Gyr with a small contribution from younger stars. This suggests that the quenching of star formation in NGC 4371, which is very likely an environmental effect, was already occurring at a redshift of about z = 0.8 +0.2 −0.1 . Our results suggest that bar-driven secular evolution processes may have an extended impact on the evolution of galaxies, and thus on the properties of galaxies as observed today, and not necessarily be restricted to more recent cosmic epochs.

show abstract

Section: Environmental Effects: the Lack Of Gas And Recent Star Formamentioning

confidence: 99%

MUSE tells the story of NGC 4371: The dawning of secular evolution

Gadotti¹,

Seidel²,

Sánchez‐Blázquez³

et al. 2015

A&A

134

View full text Add to dashboard Cite

show abstract

“…James et al 2005). Most frequently used narrow-band filters have a width of ∼50−80 Å, and in most of the cases the emission from the [N ii] λλ6548, 6583 contaminate the derived Hα emission map, and therefore, the derived Hα luminosity and SFR.…”

Section: Appendix A: Catalogues Of the H II Regionsmentioning

confidence: 99%

Integral field spectroscopy of a sample of nearby galaxies

Sánchez

Rosales-Ortega

Marino

et al. 2012

A&A

188

189

View full text Add to dashboard Cite

We analyse the spectroscopic properties of thousands of H ii regions identified in 38 face-on spiral galaxies. All galaxies were observed out to 2.4 effective radii using integral field spectroscopy (IFS) over the wavelength range ∼3700 to ∼6900 Å. The near uniform sample has been assembled from the PPAK IFS Nearby Galaxy (PINGS) survey and a sample described in Paper I. We develop a new automatic procedure to detect H ii regions, based on the contrast of the Hα intensity maps extracted from the datacubes. Once detected, the algorithm provides us with the integrated spectra of each individual segmented region. In total, we derive good quality spectroscopic information for ∼2600 independent H ii regions/complexes. This is by far the largest H ii region survey of its kind. Our selection criteria and the use of 3D spectroscopy guarantee that we cover the regions in an unbiased way. A welltested automatic decoupling procedure has been applied to remove the underlying stellar population, deriving the main properties (intensity, dispersion and velocity) of the strongest emission lines in the considered wavelength range (covering from [O ii] λ3727 to [S ii] λ6731). A final catalogue of the spectroscopic properties of H ii regions has been created for each galaxy, which includes information on morphology, spiral structure, gas kinematics, and surface brightness of the underlying stellar population. In the current study, we focus on the understanding of the average properties of the H ii regions and their radial distributions. We find a significant change in the ionisation characteristics of H ii regions within r < 0.25 r e due to contamination from sources with different ionising characteristics, as we discuss. We find that the gas-phase oxygen abundance and the Hα equivalent width present a negative and positive gradient, respectively. The distribution of slopes is statistically compatible with a random Gaussian distribution around the mean value, if the radial distances are measured in units of the respective effective radius. No difference in the slope is found for galaxies of different morphologies, e.g. barred/non-barred, grand-design/flocculent. Therefore, the effective radius is a universal scale length for gradients in the evolution of galaxies. Some properties have a large variance across each object and between galaxies (e.g. electron density) without a clear characteristic value. But other properties are well described by an average value either galaxy by galaxy or among the different galaxies (e.g. dust attenuation).

show abstract

“…As previous authors have pointed out (i.e. Dopita et al 2002;James et al 2005), the correction of the Hα fluxes for both extinction and [N ii] emission is vital to a reliable estimation of the SFR using Hα-images.…”

Section: Analysis Of the Star-formation Ratesmentioning

confidence: 99%

Massive star formation in Wolf-Rayet galaxies

López-Sánchez

2010

A&A

View full text Add to dashboard Cite

Aims. We performed a comprehensive analysis of a sample of 20 starburst galaxies that show a substantial population of very young massive stars, most of them classified as Wolf-Rayet galaxies. Methods. In this paper, the last in the series, we analyze the global properties of our galaxy sample using multiwavelength data extracted from our own observations (Hα fluxes, B and H-band magnitudes) and from the literature, which include X-ray, FUV, FIR, and radio (both H i spectral line and 1.4 GHz radio-continuum) measurements.Results. The agreement between our Hα-based star-formation rates (Sfr) and those provided by indicators at other wavelengths is remarkable, but we consider that the new Hα-based calibration provided by Calzetti et al. (2007, ApJ, 666, 870) should be preferred to older calibrations. The FUV-based Sfr provides a powerful tool for analyzing the star-formation activity on both global and local scales independently to the Hα emission. We provide empirical relationships between the ionized gas mass, neutral gas mass, dust mass, stellar mass, and dynamical mass with the B-luminosity. Although all mass estimations increase with increasing luminosity, we find important deviations to the general trend in some objects, which seem to be the consequence of their particular evolutionary histories. The analysis of the mass-to-light ratios give similar results. We investigate the mass-metallicity relations and conclude that both the nature and the star-formation history are needed to understand the relationships between both properties. The majority of the galaxies follow a Schmidt-Kennicutt scaling law of star-formation that agrees with that reported in individual star-forming regions within M 51 but not with that found in normal spiral galaxies. Dwarf galaxies seem to be forming stars more efficiently than the outskirts of spiral galaxies. We find a relation between the reddening coefficient and the warm dust mass indicating that the extinction is mainly internal to the galaxies. The comparison with the closed-box model also indicates that the environment has strongly affected their evolution. Conclusions. Considering all multiwavelength data, we found that 17 up to 20 galaxies are clearly interacting or merging with lowluminosity dwarf objects or H i clouds. The remaining three galaxies (Mkn 5, SBS 1054+364, and SBS 1415+437) show considerable divergences of some properties when comparing with similar objects. Many of the interacting/merging features are only detected when deep optical spectroscopy and a detailed multiwavelength analysis, including H i observations, are obtained. We conclude that interactions do play a fundamental role in the triggering mechanism of the strong star-formation activity observed in dwarf starburst galaxies.

show abstract

The Hα Galaxy Survey

Cited by 47 publications

References 56 publications

MUSE tells the story of NGC 4371: The dawning of secular evolution

MUSE tells the story of NGC 4371: The dawning of secular evolution

Integral field spectroscopy of a sample of nearby galaxies

Massive star formation in Wolf-Rayet galaxies

Contact Info

Product

Resources

About