Star Formation Rates of Local Blue Compact Dwarf Galaxies. I. 1.4 GH[CLC]z[/CLC] and 60 Micron Luminosities

Hopkins, A. M.; Schulte-Ladbeck, R. E.; Drozdovsky, I.

doi:10.1086/341584

Cited by 82 publications

(121 citation statements)

References 56 publications

(78 reference statements)

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“…A search for extended emission using IRAS maps, from which the foreground Galactic dust emission had been subtracted using H i data from GASS (N. McClure-Griffiths et al 2009, in preparation), also reveal no excess emission above a 3σ limit of around 0.24 MJy sr −1 . Translated to a limit on the star formation rate (using the 0.1-100 M formula of Hopkins et al 2002), the latter suggests an upper limit of ∼1.5 × 10 −5 M yr −1 over a region of size 220 pc (the GASS resolution at a distance of 50 kpc). No doubt these heuristic estimators of star formation break down at small spatial scales and at such small star formation rates, but it remains likely that star formation in this part of the Stream is exceedingly low and probably non-existent.…”

Section: Spectral Analysismentioning

confidence: 99%

Cool Gas in the Magellanic Stream

Matthews¹,

Dyson²,

Müller³

2009

ApJ

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We present the first direct detection of cold atomic gas in the Magellanic Stream, through 21 cm line absorption toward a background radio source, J0119−6809, using the Australia Telescope Compact Array. Two absorption components were identified at heliocentric velocities 218.6 km s −1 and 227.0 km s −1 , with optical depths of τ ≈ 0.02. The corresponding H i emission region has a column density in excess of 2 × 10 20 cm −2 . The inferred spin temperature of the emitting gas is ∼ 70 K. We failed to find cool gas in observations of three other radio continuum sources. Although we have definitively detected cool gas in the Stream, its spin temperature is higher than similar components in the LMC, SMC, and Bridge, and its contribution to the total H i density is probably lower. No corresponding 12 CO(J = 1→ 0) or dust appears to be associated with the cool gas, suggesting that the cloud is not forming stars.

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Section: Spectral Analysismentioning

confidence: 99%

Cool Gas in the Magellanic Stream

Matthews¹,

Dyson²,

Müller³

2009

ApJ

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“…Many processes linked to star formation such as stellar winds (Hoefner 2009), supernovae shocks, photodestruction by high-mass stars etc. can Article published by EDP Sciences Meurer et al (1992), Haro 11: Bergvall & Östlin (2002), Mrk 1089 and UM 311: Hopkins et al (2002). b References for distances: NGC 1705: Meurer et al (1992), Haro 11: Bergvall et al (2000), Mrk 1089 and UM 311: Hopkins et al (2002).…”

Section: Introductionmentioning

confidence: 99%

“…can Article published by EDP Sciences Meurer et al (1992), Haro 11: Bergvall & Östlin (2002), Mrk 1089 and UM 311: Hopkins et al (2002). b References for distances: NGC 1705: Meurer et al (1992), Haro 11: Bergvall et al (2000), Mrk 1089 and UM 311: Hopkins et al (2002). c References for the HI mass: NGC 1705: 8.9 × 10 7 M for D = 6.2 Mpc (Meurer et al 1998), Haro 11: upper limit derived from the HI detection (Bergvall & Östlin 2002), Mrk 1089: 2.1 × 10 10 M for D = 53 Mpc (Williams et al 1991), UM 311: 3.1 × 10 9 M for D = 24.7 Mpc (Smoker et al 2000).…”

Section: Introductionmentioning

confidence: 99%

Probing the dust properties of galaxies up to submillimetre wavelengths

Galametz¹,

Madden²,

Galliano³

et al. 2009

A&A

100

200

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Aims. We study the dust properties of four low metallicity galaxies by modelling their spectral energy distributions. This modelling enables us to constrain the dust properties such as the mass, the temperature or the composition to characterise the global ISM properties in dwarf galaxies. Methods. We present 870 μm images of four low metallicity galaxies (NGC 1705, Haro 11, Mrk 1089 and UM 311) observed with the Large APEX BOlometer CAmera (LABOCA) on the Atacama Pathfinder EXperiment (APEX) telescope. We modeled their spectral energy distributions combining the submm observations of LABOCA, 2MASS, IRAS, Spitzer photometric data, and the IRS data for Haro 11. Results. We found that the PAH mass abundance is very low in these galaxies, 5 to 50 times lower than the PAH mass fraction of our Galaxy. We also found that a significant mass of dust is revealed when using submm constraints compared to that measured with only mid-IR to far-IR observations extending only to 160 μm. For NGC 1705 and Haro 11, an excess in submillimeter wavelengths was detected when we used our standard dust SED model. We rerun our SED procedure adding a cold dust component (10 K) to better describe the high 870 μm flux derived from LABOCA observations, which significantly improves the fit. We found that at least 70% of the dust mass of these two galaxies can reside in a cold dust component. We also showed that the subsequent dust-to-gas mass ratios, considering HI and CO observations, can be strikingly high for Haro 11 in comparison with what is usually expected for these low-metallicity environments. Furthermore, we derived the star formation rate of our galaxies and compared them to the Schmidt law. Haro 11 falls anomalously far from the Schmidt relation. These results may suggest that a reservoir of hidden gas could be present in molecular form not traced by the current CO observations. While there can be a significant cold dust mass found in Haro 11, the SED peaks at exceptionally short wavelengths (36 μm), also highlighting the importance of the much warmer dust component heated by the massive star clusters in Haro 11. We also derived the total IR luminosities derived from our models and compared them with relations that derive this luminosity from Spitzer bands. We found that the Draine & Li (2007) formula compares well to our direct IR determinations.

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“…Observations of local and distant luminous blue galaxies (LBG) and Lyman break galaxies seem to confirm that galaxy interactions are more common at high redshifts (e.g., Guzman et al 1997;Hopkins et al 2002;Erb et al 2003;Werk et al 2004;Colina et al 2005;Overzier et al 2009;Cardamone et al 2009), but many details are still A&A 521, A63 (2010) unclear (i.e., Basu-Zych et al 2009). Indeed, detailed studies of local interacting/merging galaxies provide vital clues to galaxy formation and evolution, as they constrain the properties of the hierarchical formation models.…”

Section: Introductionmentioning

confidence: 99%

Massive star formation in Wolf-Rayet galaxies

López-Sánchez

2010

A&A

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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.

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Star Formation Rates of Local Blue Compact Dwarf Galaxies. I. 1.4 GH[CLC]z[/CLC] and 60 Micron Luminosities

Cited by 82 publications

References 56 publications

Cool Gas in the Magellanic Stream

Cool Gas in the Magellanic Stream

Probing the dust properties of galaxies up to submillimetre wavelengths

Massive star formation in Wolf-Rayet galaxies

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