The Small Magellanic Cloud in the far infrared

Wilke, Karsten; Klaas, U.; Lemke, D.; Mattila, K.; Stickel, M.; Haas, Martín

doi:10.1051/0004-6361:20034113

Cited by 57 publications

(66 citation statements)

References 31 publications

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“…Based on far-infrared dust emission and Hα emission, Wilke et al (2004) deduced a presentday SFR of ∼0.05 M ⊙ yr −1 , in good agreement with the value of Harris & Zaritsky (2004) and with previous estimates. By comparison, a review of the SFR estimates for the Milky Way by Diehl et al (2006) shows that a value of 4 ±2 M ⊙ yr −1 can be adopted.…”

Section: Injection and Transportsupporting

confidence: 88%

“…So instead of trying to compute these volumes, we used the interstellar radiation field density as an indicator of the star formation per unit volume. The average temperature of the dust is observed to be higher in the SMC than in the Milky Way, suggesting a stronger interstellar radiation field (Stanimirovic et al 2000;Wilke et al 2004). This could be due to the lower metallicity of the SMC, but may also be the consequence of a higher SFR per unit volume.…”

Section: Injection and Transportmentioning

confidence: 99%

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Detection of the Small Magellanic Cloud in gamma-rays with Fermi/LAT

Abdo¹,

Ackermann²,

Ajello³

et al. 2010

A&A

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Context. The flux of gamma rays with energies greater than 100 MeV is dominated by diffuse emission coming from cosmic-rays (CRs) illuminating the interstellar medium (ISM) of our Galaxy through the processes of Bremsstrahlung, pion production and decay, and inverse-Compton scattering. The study of this diffuse emission provides insight into the origin and transport of cosmic rays. Aims. We searched for gamma-ray emission from the Small Magellanic Cloud (SMC) in order to derive constraints on the cosmic-ray population and transport in an external system with properties different from the Milky Way. Methods. We analysed the first 17 months of continuous all-sky observations by the Large Area Telescope (LAT) of the Fermi mission to determine the spatial distribution, flux and spectrum of the gamma-ray emission from the SMC. We also used past radio synchrotron observations of the SMC to study the population of CR electrons specifically. Results. We obtained the first detection of the SMC in high-energy gamma rays, with an integrated >100 MeV flux of (3.7 ±0.7) × 10 −8 ph cm −2 s −1 , with additional systematic uncertainty of ≤ 16%. The emission is steady and from an extended source ∼ 3 • in size. It is not clearly correlated with the distribution of massive stars or neutral gas, nor with known pulsars or supernova remnants, but a certain correlation with supergiant shells is observed. Conclusions. The observed flux implies an upper limit on the average CR nuclei density in the SMC of ∼15% of the value measured locally in the Milky Way. The population of high-energy pulsars of the SMC may account for a substantial fraction of the gamma-ray flux, which would make the inferred CR nuclei density even lower. The average density of CR electrons derived from radio synchrotron observations is consistent with the same reduction factor but the uncertainties are large. From our current knowledge of the SMC, such a low CR density does not seem to be due to a lower rate of CR injection and rather indicates a smaller CR confinement volume characteristic size.

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Section: Injection and Transportsupporting

confidence: 88%

Section: Injection and Transportmentioning

confidence: 99%

Detection of the Small Magellanic Cloud in gamma-rays with Fermi/LAT

Abdo¹,

Ackermann²,

Ajello³

et al. 2010

A&A

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“…In Table 2 we have compiled important physical parameters of the emission knots: Size, corresponding to n pix of the HIIphot aperture (Col. 2), far-infrared luminosity, derived from multi-component modified BB fits to the photometry of Table 1 (Col. 3), colour temperature for a modified BB with β = 2 (Col. 4), dust mass, as described in Wilke et al (2004) (Col. 5), molecular gas mass, adding up all GMCs listed by Wilson et al (2003) in the HIIphot aperture and re-scaling the distance (Col. 6), star formation rate and star formation density A&A 518, L44 (2010) according to Kennicutt (1998) (Cols. 7 & 8), star formation efficiency as the ratio of far-infrared luminosity and molecular gas mass (Col. 9), 6 cm radio flux from Hummel & van der Hulst (1986) (Col. 10), and radio to far-infrared flux ratio according to de Jong et al (1985) (Col. 11).…”

Section: Resultsmentioning

confidence: 99%

Tracing the sites of obscured star formation in the Antennae galaxies withHerschel-PACS

Klaas

Nielbock

Haas

et al. 2010

A&A

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Aims. FIR imaging of interacting galaxies allows locating even hidden sites of star formation and measuring of the relative strength of nuclear and extra-nuclear star formation. We want to resolve the star-forming sites in the nearby system of the Antennae. Methods. Thanks to the unprecedented sharpness and depth of the PACS camera onboard ESA's Herschel Space Observatory, it is possible for the first time to achieve a complete assessment of individual star-forming knots in the FIR with scan maps at 70, 100, and 160 μm. We used clump extraction photometry and SED diagnostics to derive the properties related to star-forming activity. Results. The PACS 70, 100, and 160 μm maps trace the knotty structure of the most recent star formation along an arc between the two nuclei in the overlap area. The resolution of the starburst knots and additional multi-wavelength data allow their individual star formation history and state to be analysed. In particular, the brightest knot in the mid-infrared (K1), east of the southern nucleus, exhibits the highest activity by far in terms of dust heating and star formation rate, efficiency, and density. With only 2 kpc in diameter, this area has a 10-1000 μm luminosity, which is as high as that of our Milky Way. It shows the highest deficiency in radio emission in the radio-to-FIR luminosity ratio and a lack of X-ray emission, classifying it as a very young complex. The brightest 100 and 160 μm emission region (K2), which is close to the collision front and consists of 3 knots, also shows a high star formation density and efficiency and lack of X-ray emission in its most obscured part, but an excess in the radio-to-FIR luminosity ratio. This suggests a young stage, too, but different conditions in its interstellar medium. Our results provide important checkpoints for numerical simulations of interacting galaxies when modelling the star formation and stellar feedback.

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“…not corrected for extinction) from the Third Reference Catalog of Bright Galaxies, (RC 3 -de Vaucouleurs et al 1991), we have used radio data obtained or collected by Loiseau et al (1987), Mountfort et al (1987), Alvarez et al (1987Alvarez et al ( , 1989, Klein et al (1989), Ye & Turtle (1991), and Haynes et al (1991). Infrared and submillimeter continuum data were taken from Schwering (1988), Rice et al (1988), Stanimirovic et al (2000), Aguirre et al (2003), Wilke et al (2004), Hughes et al (2006), Bolatto et al (2007), and Leroy et al (2007). The ultraviolet data of the LMC are those of Page & Carruthers (1981).…”

Section: Literature Datamentioning

confidence: 99%

Submillimeter to centimeter excess emission from the Magellanic Clouds

Israel¹,

Wall

Raban³

et al. 2010

A&A

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Aims. Our goal is to determine and study the global emission from the Magellanic Clouds over the full radio to ultraviolet spectral range. Methods. We have selected from the literature those flux densities that include the entire LMC and SMC respectively, and we have complemented these with maps extracted from the WMAP and COBE databases covering the missing 23−90 GHz (13-3.2 mm) and the poorly sampled 1.25-250 THz (240-1.25 μm) spectral ranges in order to reconstruct the global SEDs of the Magellanic Clouds over eight decades in frequency or wavelength. Results. A major result is the discovery of a pronounced excess of emission from the Magellanic Clouds at millimeter and submillimeter wavelengths. We also confirm global mid-infrared (12 μm) emission suppression, and determine accurate thermal radio fluxes and very low global extinctions for both LMC and SMC, the latter being the most extreme in all these respects. Conclusions. These and other dust properties such as the far-UV extinction curve appear to be correlated with (low) metallicity. Possible explanations are briefly considered. As long as the nature of the excess emission is unknown, the total dust masses and gas-to-dust ratios of the Magellanic Clouds cannot reliably be determined

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The Small Magellanic Cloud in the far infrared

Cited by 57 publications

References 31 publications

Detection of the Small Magellanic Cloud in gamma-rays with Fermi/LAT

Detection of the Small Magellanic Cloud in gamma-rays with Fermi/LAT

Tracing the sites of obscured star formation in the Antennae galaxies withHerschel-PACS

Submillimeter to centimeter excess emission from the Magellanic Clouds

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