The Spectrum of Integrated Millimeter Flux of the Magellanic Clouds and 30 Doradus from TopHat and DIRBE Data

Aguirre, James E.; Bezaire, J. J.; Cheng, E. S.; Cottingham, D. A.; Cordone, S.; Crawford, T. M.; Fixsen, D. J.; Knox, L.; Meyer, S. S.; Nørgaard-Nielsen, H. U.; Silverberg, R. F.; Timbie, Peter; Wilson, Grant

doi:10.1086/377601

Cited by 47 publications

(72 citation statements)

References 37 publications

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“…For the LMC, the observed emission is well fitted from infrared to millimeter, as well as in the radio domain. TopHat fluxes at (sub-)millimeter wavelength (475 μm to 1.22 mm Aguirre et al 2003) are well reproduced by the expected dust emission fitted to the infrared emission. We observe a small, but significant excess (6−7σ) emission in the first three WMAP bands at 3.3, 5 and 7.5 mm (90, 60 and 40 GHz), above extrapolated models (dust, freefree and synchrotron).…”

Section: Integrated Spectra Of the Magellanic Cloudsmentioning

confidence: 59%

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Submillimeter to centimeter excess emission from the Magellanic Clouds

Bot

Ysard

Paradis

et al. 2010

A&A

111

140

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Context. Dust emission at sub-millimeter to centimeter wavelengths is often simply the Rayleigh-Jeans tail of dust particles at thermal equilibrium and is used as a cold mass tracer in various environments, including nearby galaxies. However, well-sampled spectral energy distributions of the nearby, star-forming Magellanic Clouds have a pronounced (sub-)millimeter excess. Aims. This study attempts to confirm the existence of this millimeter excess above expected dust, free-free and synchrotron emission and to explore different possibilities for its origin. Methods. We model near-infrared to radio spectral energy distributions of the Magellanic Clouds with dust, free-free, and synchrotron emission. A millimeter excess emission is confirmed above these components and its spectral shape and intensity are analyzed in light of different scenarios: very cold dust, cosmic microwave background (CMB) fluctuations, a change of the dust spectral index and spinning dust emission. Results. We show that very cold dust or CMB fluctuations are very unlikely explanations for the observed excess in these two galaxies. The excess in the Large Magellanic Cloud can be satisfactorily explained either by a change of the spectral index related to intrinsic properties of amorphous grains, or by spinning dust emission. In the Small Magellanic Cloud, however, the excess is larger and the dust grain model including TLS/DCD effects cannot reproduce the observed emission in a simple way. A possible solution was achieved with spinning dust emission, but many assumptions on the physical state of the interstellar medium had to be made. Conclusions. Further studies, with higher resolution data from Planck and Herschel are needed to probe the origin of this observed submillimeter-centimeter excess more definitely. Our study shows that the different possible origins will be best distinguished where the excess is the highest, as is the case in the Small Magellanic Cloud.

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Section: Integrated Spectra Of the Magellanic Cloudsmentioning

confidence: 59%

“…This sub-millimeter excess is then alternatively attributed to variations of optical properties of dust grains. For example, low spectral emissivity index values, β, might apply (Dupac et al 2003b;Aguirre et al 2003). Spectral emissivity index variations with dust temperature have been noted (Dupac et al 2003a;Désert et al 2008).…”

Section: Introductionmentioning

confidence: 99%

Submillimeter to centimeter excess emission from the Magellanic Clouds

Bot

Ysard

Paradis

et al. 2010

A&A

111

140

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“…This model suggests that a sufficient abundance of the CO 2 ice can be produced at relatively high dust temperatures, but this process is quite sensitive to the dust temperature and other assumed conditions. Several studies report that the interstellar dust temperature in the LMC is generally higher than in our Galaxy based on far-infrared to submillimeter observations of diffuse emission (e.g., Aguirre et al 2003;Sakon et al 2006). In addition, van Loon et al (2010a,b) derived the dust temperatures of YSOs in the LMC and Small Magellanic Cloud (SMC) and suggest that the dust temperatures become higher in more metal-poor environments of the SMC.…”

Section: Large Co 2 /H 2 O Ice Ratio In the Lmcmentioning

confidence: 76%

Spectroscopic observations of ices around embedded young stellar objects in the Large Magellanic Cloud with AKARI

Shimonishi

Onaka

Kato

et al. 2010

A&A

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Aims. The aim of this study is to understand the chemical conditions of ices around embedded young stellar objects (YSOs) in the metal-poor Large Magellanic Cloud (LMC). Methods. We performed near-infrared (2.5−5 μm) spectroscopic observations toward 12 massive embedded YSOs and their candidates in the LMC using the infrared camera (IRC) onboard AKARI. We estimated the column densities of the H 2 O, CO 2 , and CO ices based on their 3.05, 4.27, and 4.67 μm absorption features, and we investigated the correlation between ice abundances and physical properties of YSOs. Results. The ice absorption features of H 2 O, CO 2 , 13 CO 2 , CO, CH 3 OH, and possibly XCN are detected in the spectra. In addition, hydrogen recombination lines and PAH emission bands are detected toward the majority of the targets. The derived typical CO 2 /H 2 O ice ratio of our samples (∼0.36 ± 0.09) is greater than that of Galactic massive YSOs (∼0.17 ± 0.03), while the CO/H 2 O ice ratio is comparable. It is shown that the CO 2 ice abundance does not correlate with the observed characteristics of YSOs: the strength of hydrogen recombination line and the total luminosity. Likewise, clear correlation is not seen between the CO ice abundance and YSO characteristics, but it is suggested that the CO ice abundance of luminous samples is significantly lower than in other samples. Conclusions. The systematic difference in the CO2 ice abundance around the LMC's massive YSOs, which was suggested by previous studies, is confirmed with the new near-IR data. We suggest that the strong ultraviolet radiation field and/or the high dust temperature in the LMC are responsible for the observed high abundance of the CO 2 ice. It is suggested that the internal stellar radiation does not play an important role in the evolution of the CO 2 ice around a massive YSO, while more volatile molecules like CO are susceptible to the effect of the stellar radiation.

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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%

“…For the former, we extrapolated the results from the preceding discussion; for the latter we extrapolated the spectral fits to the DIRBE and TopHat data published by Aguirre et al (2003) in their Fig. 4 and Table 9, assuming no additional excess to be present at their lowest frequency of 245 GHz (longest wavelength of 1200 μm).…”

Section: Lmc and Smc Millimeter And Submillimeter Spectramentioning

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 Spectrum of Integrated Millimeter Flux of the Magellanic Clouds and 30 Doradus from TopHat and DIRBE Data

Cited by 47 publications

References 37 publications

Submillimeter to centimeter excess emission from the Magellanic Clouds

Submillimeter to centimeter excess emission from the Magellanic Clouds

Spectroscopic observations of ices around embedded young stellar objects in the Large Magellanic Cloud with AKARI

Submillimeter to centimeter excess emission from the Magellanic Clouds

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