A New Spin on Galactic Dust

Oliveira-Costa, A. de; Tegmark, Max; Finkbeiner, Douglas P.; Davies, R. D.; Gutiérrez, Carlos M.; Haffner, L. M.; Jones, Aled; Lasenby, A.; Rebolo, R.; Reynolds, R. J.; Tufte, S. L.; Watson, R. A.

doi:10.1086/338109

Cited by 78 publications

(88 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Observations which show stronger correlations between the excess emis sion and the shorter-wavelength (12 and 25 /xm) IRAS bands, as compared to the longer-wavelength bands (60 and 100 /xm), clearly appear to favor spinning-dust over magnetic-dust (de Oliveira-Costa et al 2002;Casassus et al 2006). Furthermore, correlations of the microwave excess with Ha emis sion peaking at -40 GHz (Dobler & Finkbeiner 2008b;Dobler et al 2008) also favor spinning-dust in the warm ionized medium (WIM), as both Ha and WIM spinning dust are expected to be propor tional to the density squared of ions.…”

Section: Additional Polarized Componentsmentioning

confidence: 99%

Prospects for polarized foreground removal

Amblard¹,

Baccigalupi²,

Betoule³

et al. 2009

AIP Conference Proceedings

View full text Add to dashboard Cite

In this report we discuss the impact of polarized foregrounds on a future CMBPol satellite mission. We review our current knowledge of Galactic polarized emission at microwave frequencies, including synchrotron and thermal dust emission. We use existing data and our understanding of the physical behavior of the sources of foreground emission to generate sky templates, and start to assess how well primordial gravitational wave signals can be separated from foreground contaminants for a CMBPol mission. At the estimated foreground minimum of -100 GHz, the polarized foregrounds are expected to be lower than a primordial polarization signal with tensor-to-scalar ratio r = 0.01, in a small patch (~ 1%) of the sky known to have low Galactic emission. Over 75% of the sky we expect the foreground amplitude to exceed the primordial signal by about a factor of eight at the foreground minimum and on scales of two degrees. Only on the largest scales does the polarized foreground amplitude exceed the primordial signal by a larger factor of about 20. The prospects for detecting an r = 0.01 signal including degree-scale measurements appear promising, with 5cr r -0.003 forecast from multiple methods. A mission that observes a range of scales offers better prospects from the foregrounds perspective than one targeting only the lowest few multipoles. We begin to explore how optimizing the composition of frequency channels in the focal plane can maximize our ability to perform component separation, with a range of typically 40 < v < 300 GHz preferred for ten channels. Foreground cleaning methods are already in place to tackle a CMBPol mission data set, and further investigation of the optimization and detectability of the primordial signal will be useful for mission design.

show abstract

Section: Additional Polarized Componentsmentioning

confidence: 99%

Prospects for polarized foreground removal

Amblard¹,

Baccigalupi²,

Betoule³

et al. 2009

AIP Conference Proceedings

View full text Add to dashboard Cite

show abstract

“…We show this in Fig. 9: here we consider the radio source counts at 33 GHz, from the model of de Zotti et al (2005). Integrating the counts we can estimate the Poisson contribution to the power spectrum.…”

Section: Dependence On the Observing Channelmentioning

confidence: 99%

Carbon monoxide line emission as a CMB foreground: tomography of the star-forming universe with different spectral resolutions

Righi¹,

Hernández-Monteagudo²,

Sunyaev

2008

A&A

138

View full text Add to dashboard Cite

Context. The rotational lines of carbon monoxide and the fine structure lines of CII and of the most abundant metals, emitted during the epoch of enhanced star formation in the universe, are redshifted in the frequency channels where the present-day and future CMB experiments are sensitive. Aims. We estimate the contribution to the CMB angular power spectrum by the emission in such lines in merging star-forming galaxies. Methods. We used the Lacey-Cole approach to characterize the distribution of the merging halos, together with a parametrization for the star formation rate in each of them. Using observational data from a sample of local, low-redshift, and high-redshift objects, we calibrated the luminosity in each line as a function of the star formation rate. Results. We show that the correlation term arising from CO line emission is a significant source of foreground for CMB in a broad range of frequencies (in particular in the 20−60 GHz band) and for 1000 < l < 8000, corresponding to angular scales smaller than 10 arcmin. Moreover, we demonstrate that observing with different spectral resolutions will give the possibility of increasing the amplitude of the signal up to two orders of magnitude in C l and will help separate the line contribution from practically all other foreground sources and from the primary fluctuations themselves, since these show no significant dependence on the spectral resolution. Conclusions. We propose to perform observations with varying spectral bandwidths (10 −3 < Δν/ν obs < 10 −1 ) as a new tool to construct a tomography of the universe, by probing different redshift slices with varying thickness. This should yield new constraints on the regions responsible for the metal enrichment in the universe and on their clustering pattern and will lead to new hints about the reionization epoch and the cosmological parameters, including σ 8 .

show abstract

“…Interstellar PAHs may thus contribute significantly to the emission at long wavelength (λ > 1 mm). In this context, an unexpected emission excess called anomalous foreground, correlated to dust emission, has been discovered between 10 and 90 GHz (Leitch et al 1997;de Oliveira-Costa et al 2002). In this spectral range, several galactic emission components (synchrotron, freefree, and thermal dust) contribute with a comparable magnitude, and only recently has the anomalous foreground been separated in WMAP data (Miville-Deschênes et al 2008).…”

Section: Introductionmentioning

confidence: 96%

The long-wavelength emission of interstellar PAHs: characterizing the spinning dust contribution

Ysard¹,

Verstraete²

2010

A&A

View full text Add to dashboard Cite

Context. The emission of cold dust grains at long wavelengths will soon be observed by the Planck and Herschel satellites and will provide new constraints on the nature of interstellar dust. In particular, the microwave galactic anomalous foreground detected between 10 to 90 GHz, proposed as coming from small spinning grains (PAHs), should help to define these species better. Moreover, understanding the fluctuations of the anomalous foreground quantitatively over the sky is crucial for CMB studies. Aims. We focus on the long-wavelength emission of interstellar PAHs in their vibrational and rotational transitions. We present here the first model that coherently describes the PAH emission from the near-IR to microwave range. Methods. We take quantum effects into account to describe the rotation of PAHs and compare our results to current models of spinning dust to assess the validity of the classical treatment used. Between absorptions of stellar photons, we followed the rovibrational radiative cascade of PAHs. We used the exact-statistical method of Draine & Li to derive the distribution of PAH internal energy and followed a quantum approach for the rotational excitation induced by vibrational (IR) transitions. We also examined the influence of the vibrational relaxation scheme and of the low-energy cross-section on the PAH emission. We study the emissivity of spinning PAHs in a variety of physical conditions (radiation field intensity and gas density), search for specific signatures in this emission that can be looked for observationally, and discuss how the anomalous foreground may constrain the PAH size distribution. Results. Simultaneously predicting the vibrational and rotational emission of PAHs, our model can explain the observed emission of the Perseus molecular cloud from the IR to the microwave range with plausible PAH properties. We show that for λ ≥ 3 mm the PAH vibrational emission no longer scales with the radiation field intensity (G 0 ), unlike the mid-IR part of the spectrum (which scales with G 0 ). This emission represents less than 10% of the total dust emission at 100 GHz. Similarly, we find the broadband emissivity of spinning PAHs per carbon atom to be rather constant for G 0 ≤ 100 and for proton densities n H < 100 cm −3 . In the diffuse ISM, photon exchange and gas-grain interactions play comparable roles in exciting the rotation of PAHs, and the emissivity of spinning PAHs is dominated by the contribution of small species (bearing less than 100 C atoms). We show that the classical description of rotation used in previous works is a good approximation and that unknowns in the vibrational relaxation scheme and low-energy cross-section affect the PAH rotational emissivity around 30 GHz by less than 15%. Conclusions. The contrasted behaviour of the PAH vibrational and rotational emissivities with G 0 provides a clear prediction that can be tested against observations of anomalous and dust mid-IR emissions: this is the subject of a companion paper. Comparison of these emissions complem...

show abstract

A New Spin on Galactic Dust

Cited by 78 publications

References 29 publications

Prospects for polarized foreground removal

Prospects for polarized foreground removal

Carbon monoxide line emission as a CMB foreground: tomography of the star-forming universe with different spectral resolutions

The long-wavelength emission of interstellar PAHs: characterizing the spinning dust contribution

Contact Info

Product

Resources

About