The First Deep Advanced Camera for Surveys Lyα Images of Local Starburst Galaxies

Kunth, D.; Leitherer, Claus; Mas-Hesse, J. M.; Östlin, Göran; Петросян, А. Р.

doi:10.1086/378396

Cited by 101 publications

(133 citation statements)

References 19 publications

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“…While none of the clusters show Lyα emission, SSCs 4 and 5 are considerably brighter than SSCs 1 and 2 in the far-ultraviolet continuum (Kunth et al 2003). This is consistent with SSCs 1 and 2 having younger ages and thus suffering from more extinction in the natal cloud.…”

Section: Age Of the Sscssupporting

confidence: 72%

Probing Star Formation at Low Metallicity: The Radio Emission of Super Star Clusters in SBS 0335–052

Johnson

Hunt²,

Reines

2009

The Astronomical Journal

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We present high-resolution radio-continuum observations of the nascent starburst in the metal-poor galaxy SBS 0335−052. These radio data were taken with the Very Large Array and include observations at 0.7 cm, 1.3 cm, 2 cm, 3.6 cm, and 6 cm. These observations enable us to probe the thermal radio nebulae associated with the extremely young star-forming regions in this galaxy. Two discrete and luminous star-forming regions are detected in the south of the galaxy that appear to be associated with massive star clusters previously identified at optical wavelengths. However, the remaining optically identified massive star clusters are not clearly associated with radio emission (either thermal or nonthermal) down to the sensitivity limits of these radio data. The spectral energy distributions (SEDs) of the two radio-detected clusters are consistent with being purely thermal, and the entire region has an inferred ionizing flux of ∼1.2 × 10 53 s −1 , which is equivalent to ∼12,000 "typical" O-type stars (type O7.5 V). The observations presented here have resolved out a significant contribution from diffuse nonthermal emission detected previously, implying a previous episode of significant star formation. The current star formation rate (SFR) for this southern region alone is ∼1.3 M yr −1 , or ∼23 M yr −1 kpc −2 , which is nearing the maximum starburst intensity limit. This SFR derived from thermal radio emission also suggests that previous optical recombination line studies do not detect a significant fraction of the current star formation in SBS 0335−052. From model fits to the radio SED, we infer a global mean density in the two youngest clusters of n e 10 3 -10 4 cm −3 . In addition, a comparison between the compact and diffuse radio emission indicates that up to ∼50% of the ionizing flux could be leaking out of the compact H ii regions; this in is agreement with previous work, which suggests that the interstellar medium surrounding the natal clusters in SBS 0335−052 is porous and clumpy.

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Section: Age Of the Sscssupporting

confidence: 72%

Probing Star Formation at Low Metallicity: The Radio Emission of Super Star Clusters in SBS 0335–052

Johnson

Hunt²,

Reines

2009

The Astronomical Journal

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“…This galaxy consists of three major star-forming condensations although Lyα is seen directly in emission from only one (the NW knot; C in the nomenclature of Kunth et al 2003). It is this knot that causes the high surface brightness features discussed in Section 4.4.…”

Section: Comments On Individual Targetsmentioning

confidence: 99%

“…The intent was to map Lyα morphology and study the effects of dust, kinematics, and luminosity on the escape of Lyα and the sample was hand-picked to reflect a range of these parameters. First results were presented in Kunth et al (2003).…”

Section: Introductionmentioning

confidence: 99%

The Lyman Alpha Morphology of Local Starburst Galaxies: Release of Calibrated Images

Östlin

Hayes

Kunth

et al. 2009

The Astronomical Journal

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132

110

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We present reduced and calibrated high resolution Lyman-alpha (Lyα) images for a sample of six local starforming galaxies. Targets were selected to represent a range in luminosity and metallicity and to include both known Lyα emitters and nonemitters. Far ultraviolet imaging was carried out with the Solar Blind Channel of the Advanced Camera for Surveys on the Hubble Space Telescope (HST) in the F122M (Lyα online) and F140LP (continuum) filters. The resulting Lyα images are the product of careful modeling of both the stellar and nebular continua, facilitated by supporting HST imaging at λ ≈ 2200, 3300, 4400, 5500, Hα, and 8000 Å, combined with Starburst 99 evolutionary synthesis models, and prescriptions for dust extinction on the continuum. In all, the resulting morphologies in Lyα, Hα, and UV continuum are qualitatively very different and we show that the bulk of Lyα emerges in a diffuse component resulting from resonant scattering events. Lyα escape fractions, computed from integrated Hα luminosities and recombination theory, are found never to exceed 14%. Internal dust extinction is estimated in each pixel and used to correct Lyα fluxes. However, the extinction corrections are far too small (by factors from 2.6 to infinity) to reconcile the emerging global Lyα luminosities with standard recombination predictions. Surprisingly, when comparing the global equivalent widths of Lyα and Hα, the two quantities appear to be anticorrelated, which may be due to the evolution of mechanical feedback from the starburst. This calls for caution in the interpretation of Lyα observations in terms of star formation rates. The images presented have a physical resolution 3 orders of magnitude better than attainable at high redshifts from the ground with current instrumentation and our images may therefore serve as useful templates for comparing with observations and modeling of primeval galaxy formation. We therefore provide the reduced Lyα, Hα, and continuum images to the community.

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“…The two local comparison objects are Haro 11 and VV 114, both of which lie at z ¼ 0:02 (for details see Knop et al 1994;Scoville et al 2000;Goldader et al 2002;Bergvall & Ö stlin 2002;Kunth et al 2003;Grimes et al 2006, 2007 andreferences therein). Haro 11 is a BCD galaxy consisting of a number of UV-bright knots believed to be in the process of merging.…”

Section: Archival Imaging Data Of Haro 11 and Vv 114mentioning

confidence: 99%

Hubble Space TelescopeMorphologies of Local Lyman Break Galaxy Analogs. I. Evidence for Starbursts Triggered by Merging

Overzier

Heckman

Kauffmann

et al. 2008

ApJ

127

165

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Heckman and coworkers used the GALEX UV imaging survey to show that there exists a rare population of nearby compact UV-luminous galaxies (UVLGs) that closely resemble high-redshift Lyman break galaxies (LBGs). We present HST images in the UV, optical, and H and resimulate them at the depth and resolution of the GOODS/UDF fields to show that the morphologies of UVLGs are also similar to those of LBGs. Our sample of eight LBG analogs thus provides detailed insight into the connection between star formation and LBG morphology. Faint tidal features or companions can be seen in all of the rest-frame optical images, suggesting that the starbursts are the result of a merger or interaction. The UV/optical light is dominated by unresolved ($100Y300 pc) super starburst regions (SSBs). A detailed comparison with the galaxies Haro 11 and VV 114 at z ¼ 0:02 indicates that the SSBs themselves consist of diffuse stars and (super) star clusters. The structural features revealed by the new HST images occur on very small physical scales and are thus not detectable in images of high-redshift LBGs, except in a few cases where they are magnified by gravitational lensing. We propose, therefore, that LBGs are mergers of gas-rich, relatively low-mass (M Ã $ 10 10 M ) systems, and that the mergers trigger the formation of SSBs. If galaxies at high redshifts are dominated by SSBs, then the faint-end slope of the luminosity function is predicted to have slope $ 2. Our results are the most direct confirmation to date of models that predict that the main mode of star formation in the early universe was highly collisional.

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The First Deep Advanced Camera for Surveys Lyα Images of Local Starburst Galaxies

Cited by 101 publications

References 19 publications

Probing Star Formation at Low Metallicity: The Radio Emission of Super Star Clusters in SBS 0335–052

Probing Star Formation at Low Metallicity: The Radio Emission of Super Star Clusters in SBS 0335–052

The Lyman Alpha Morphology of Local Starburst Galaxies: Release of Calibrated Images

Hubble Space TelescopeMorphologies of Local Lyman Break Galaxy Analogs. I. Evidence for Starbursts Triggered by Merging

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