Far-Infrared Spectral Observations of the Galaxy by COBE

Reach, W. T.; Dwek, Eli; Fixsen, D. J.; Hewagama, T.; Mather, John C.; Shafer, R. A.; Banday, A. J.; Bennett, C. L.; Cheng, E. S.; Eplee, Robert E.; Leisawitz, David; Lubin, P. M.; Read, S. M.; Rosen, Lawrence; Shuman, F. G. D.; Smoot, G. F.; Sodroski, T. J.; Wright, E. L.

doi:10.1086/176210

Cited by 227 publications

(251 citation statements)

References 37 publications

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“…Structurally different dust grains, such as fluffy or fractal particles (Ossenkopf & Henning 1994;Paradis et al 2009) could produce the submillimeter excess. In fact, Reach et al (1995) propose this to be the explanation for the widespread cold dust component they found in the Milky Way from COBE/FIRAS measurements, after rejecting either very cold big dust grains or very small grains as a possibility. The dust grain emissivity β is not only a function of dust temperature, but it also depends on the grain composition.…”

Section: Possible Explanations For a Submillimeter Excessmentioning

confidence: 92%

“…Thus, we cannot exclude in low-metallicity star-forming galaxies such as the LMC and the SMC the predominance of a dust grain population with different optical properties causing β to be around unity, or even the inconspicuous presence of such dust in more massive metalrich spiral galaxies (such as the Milky Way, cf. Reach et al 1995). However, it is not clear what this population is (but see Mény et al 2007), or what processes would lie at the root of its dominance in both star-forming dwarf galaxies and more extreme (ultra)luminous infrared galaxies, nor is it obvious that β could be as low as zero, as appears to be the case in the SMC.…”

Section: Possible Explanations For a Submillimeter Excessmentioning

confidence: 99%

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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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Section: Possible Explanations For a Submillimeter Excessmentioning

confidence: 92%

Section: Possible Explanations For a Submillimeter Excessmentioning

confidence: 99%

Submillimeter to centimeter excess emission from the Magellanic Clouds

Israel¹,

Wall

Raban³

et al. 2010

A&A

Self Cite

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“…Although the measured temperature difference between the regions is less strong than the luminosity increase, nevertheless, we see elevated temperatures in IRDC 18454 compared to IRDC 18223. Considering the large apertures used for the SEDs, the derived average temperatures may still be dominated by the average temperature of the general ISM that is in the same range (e.g., Reach et al 1995).…”

Section: Luminous Starless Clumpsmentioning

confidence: 99%

The onset of high-mass star formation in the direct vicinity of the Galactic mini-starburst W43

Beuther

Tackenberg

Linz

et al. 2012

A&A

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Context. The earliest stages of high-mass star formation are still poorly characterized. Densities, temperatures and kinematics are crucial parameters for simulations of high-mass star formation. It is also unknown whether the initial conditions vary with environment. Aims. We want to investigate the youngest massive gas clumps in the environment of extremely active star formation. Methods. We selected the IRDC 18454 complex, directly associated with the W43 Galactic mini-starburst, and observed it in the continuum emission between 70 μm and 1.2 mm with Herschel, APEX and the 30 m telescope, and in spectral line emission of N 2 H + and 13 CO with the Nobeyama 45 m, the IRAM 30 m and the Plateau de Bute Interferometer. Results. The multi-wavelength continuum study allows us to identify clumps that are infrared dark even at 70 μm and hence the best candidates to be genuine high-mass starless gas clumps. The spectral energy distributions reveal elevated temperatures and luminosities compared to more quiescent environments. Furthermore, we identify a temperature gradient from the W43 mini-starburst toward the starless clumps. We discuss whether the radiation impact of the nearby mini-starburst changes the fragmentation properties of the gas clumps and by that maybe favors more high-mass star formation in such an environment. The spectral line data reveal two different velocity components of the gas at 100 and 50 km s −1 . While chance projection is a possibility to explain these components, the projected associations of the emission sources as well as the prominent location at the Galactic bar -spiral arm interface also allow the possibility that these two components may be spatially associated and even interacting. Conclusions. High-mass starless gas clumps can exist in the close environment of very active star formation without being destroyed. The impact of the active star formation sites may even allow for more high-mass stars to form in these 2nd generation gas clumps. This particular region near the Galactic bar -spiral arm interface has a broad distribution of gas velocities, and cloud interactions may be possible.

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“…The presence of this cold dust component is still a contentious issue in the ISM community and will have important consequences on our comprehension of ISM properties of low metallicity environments. Lisenfeld et al (2001), Reach et al (1995), Dumke et al (2004), Bendo et al (2006) or Meny et al (2007) suggested that changes in dust emission properties (changes in dust emissivity or resonances related to dust impurities) should be responsible for boosting submm emission above the 15−20 K thermal emission expected at these wavelengths. However, not all low metallicity galaxies show submm excess, as shown recently by the observations of the nearby Local Group Galaxy IC 10 (Parkin et al 2009, in prep.…”

Section: Introductionmentioning

confidence: 99%

Probing the dust properties of galaxies up to submillimetre wavelengths

Galametz¹,

Madden²,

Galliano³

et al. 2009

A&A

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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Far-Infrared Spectral Observations of the Galaxy by COBE

Cited by 227 publications

References 37 publications

Submillimeter to centimeter excess emission from the Magellanic Clouds

Submillimeter to centimeter excess emission from the Magellanic Clouds

The onset of high-mass star formation in the direct vicinity of the Galactic mini-starburst W43

Probing the dust properties of galaxies up to submillimetre wavelengths

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