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Summary of the amplitude of intensity (temperature) foregrounds from the Planck component separation 2015 results; figure taken from Planck Collaboration et al. (2016b). The brightness temperature r.m.s. against frequency, on angular scales of 40 arcmin, is plotted for each component. The width of the curves represents the variation when using 81 % and 93 % of the sky.
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Anomalous Microwave Emission (AME) is a component of diffuse Galactic radiation observed at frequencies in the range $\approx 10$-60 GHz. AME was first detected in 1996 and recognised as an additional component of emission in 1997. Since then, AME has been observed by a range of experiments and in a variety of environments. AME is spatially correla...
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... the frequency range 20-50 GHz where AME con- tributes significantly to the sky maps made by CMB exper- iments, in particular WMAP and Planck, synchrotron and AME spectra are usually indistinguishable, since the low- frequency tail of the AME spectrum is just out of range (see Fig. 6). This difficulty can clearly be seen in Fig. 6, which presents a summary of the separation of diffuse Galac- tic components on 1 • scales covering 81-93 % of the sky (Planck Collaboration et al. 2016b). A contributing factor to the degeneracy is that the synchrotron spectrum is not ex- pected to have spatially-uniform spectral index, ...
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... the frequency range 20-50 GHz where AME con- tributes significantly to the sky maps made by CMB exper- iments, in particular WMAP and Planck, synchrotron and AME spectra are usually indistinguishable, since the low- frequency tail of the AME spectrum is just out of range (see Fig. 6). This difficulty can clearly be seen in Fig. 6, which presents a summary of the separation of diffuse Galac- tic components on 1 • scales covering 81-93 % of the sky (Planck Collaboration et al. 2016b). A contributing factor to the degeneracy is that the synchrotron spectrum is not ex- pected to have spatially-uniform spectral index, nor to be exactly a power-law. These are both ...
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... quencies ≈ 10-60 GHz is now difficult to refute. The re- cent Planck component separation analysis included spin- ning dust, which used a spectral parametric fitting code to fit each pixel seperately (Planck Collaboration et al. 2016c). They found a strong component that was correlated with dust even though this was not assumed in the analysis. Fig. 6 presents a summary of the separation on large angular scales (81-93 % coverage). In this particular model, the AME is represented by a 2-component spinning dust model, which dominates the foreground emission near 20 GHz. Although the details of the separation could be in doubt (e.g., due to the fixed synchrotron spectrum) it appears to ...
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... et al. 2016b). It is therefore clear that AME is a major foreground for studying the CMB. Yet, CMB studies in intensity appear to not be limited by foregrounds (e.g., Dunkley et al. 2009a;Bennett et al. 2013;Planck Collaboration et al. 2016b), even though we know so little about AME. The question is how do we know that AME is not an issue? Fig. 6 but for polarized emission. For this case, the width of the curves represents the spread when using 73 % and 93 % of the sky. The approximate maximum amplitude from AME polarization (assuming 1% upper limit) at 30 GHz is indicated by the downward ...
Citations
... There have also been studies, notably by [14,15] and [16], of magnetic dipole radiation from ferromagnetic spinning dust, while [17] introduced improvements to account for quantum suppression of dissipation and alignment processes. For a comprehensive overview of the current state of AME research, see [18]. ...
This paper presents SpyDust, an improved and extended implementation of the spinning dust emission model based on a Fokker-Planck treatment. SpyDust serves not only as a Python successor to spdust, but also incorporates some corrections and extensions. Unlike spdust, which is focused on specific grain shapes, SpyDust considers a wider range of grain shapes and provides the corresponding grain dynamics, directional radiation field and angular momentum transports. We recognise the unique effects of different grain shapes on emission, in particular the shape-dependent mapping between rotational frequency and spectral frequency. In addition, we update the expressions for effects of electrical dipole radiation back-reaction and plasma drag on angular momentum dissipation. We also discuss the degeneracies in describing the shape of the spectral energy distribution (SED) of spinning dust grains with the interstellar environmental parameters. Using a typical Cold Neutral Medium (CNM) environment as an example, we perform a perturbative analysis of the model parameters, revealing strong positive or negative correlations between them. A principal component analysis (PCA) shows that four dominant modes can linearly capture most of the SED variations, highlighting the degeneracy in the parameter space of the SED shape in the vicinity of the chosen CNM environment. This opens the possibility for future applications of moment expansion methods to reduce the dimensionality of the encountered SED parameter space.
... The best current observational evidence for the presence of nanosilicates is from their proposed role as the source of the anomalous microwave emission (AME) (Hensley and Draine, 2017;Hoang et al., 2016). The AME is a broad foreground ISM feature centred at around 30 GHz which is most likely to originate from a population of fast spinning nanosized grains with a sufficiently large dipoles (Ali-Haïmoud et al., 2018). Quantum chemical modelling has shown that nanosilicates (unlike most carbonaceous species) have high inherent dipoles. ...
Silicate dust is found in a wide range of astrophysical environments. Nucleation and growth of silicate dust grains in circumstellar environments likely involves species with diameters ranging from <1 nm (molecular silicates) to a few nanometers (nanosilicates). When fully formed silicate grains with sizes ∼0.1 μm enter the interstellar medium, supernovae shockwaves cause collision-induced shattering which is predicted to redistribute a significant proportion of the silicate dust mass into a huge number of nanosilicates. This presumed population has thus far not been unambiguously confirmed by observation but is one of the main candidates for causing the anomalous microwave emission. By virtue of their extreme small size, nanosilicates and molecular silicates could exhibit significantly different properties to larger silicate grains, which could be of astrochemical and astrophysical importance. Herein, we briefly review the properties of these ultrasmall silicate dust species with a focus on insights arising from bottom-up atomistic computational modelling. Finally, we highlight how such modelling also has the unique potential to predict observationally verifiable spectral features of nanosilicates that may be detectable using the James Webb Space Telescope.
... There have also been studies, notably by [14,15] and [16], of magnetic dipole radiation from ferromagnetic spinning dust, while [17] introduced improvements to account for quantum suppression of dissipation and alignment processes. For a comprehensive overview of the current state of AME research, see [18]. ...
This paper presents 'SpyDust', an improved and extended implementation of the spinning dust emission model based on a Fokker-Planck treatment. 'SpyDust' serves not only as a Python successor to 'spdust', but also incorporates some corrections and extensions. Unlike 'spdust', which is focused on specific grain shapes, 'SpyDust' considers a wider range of grain shapes and provides the corresponding grain dynamics, directional radiation field and angular momentum transports. We recognise the unique effects of different grain shapes on emission, in particular the shape-dependent mapping between rotational frequency and spectral frequency. In addition, we update the expressions for effects of electrical dipole radiation back-reaction and plasma drag on angular momentum dissipation. We also discuss the degeneracies in describing the shape of the spectral energy distribution (SED) of spinning dust grains with the interstellar environmental parameters. Using a typical Cold Neutral Medium (CNM) environment as an example, we perform a perturbative analysis of the model parameters, revealing strong positive or negative correlations between them. A principal component analysis (PCA) shows that four dominant modes can linearly capture most of the SED variations, highlighting the degeneracy in the parameter space of the SED shape in the vicinity of the chosen CNM environment. This opens the possibility for future applications of moment expansion methods to reduce the dimensionality of the encountered SED parameter space.
... The AME SED is predicted to vary with physical conditions and emitting particle type (e.g. Draine & Lazarian 1998;Ali-Haïmoud et al. 2009;Silsbee et al. 2011;Hensley & Draine 2023) , but observations of individual source SEDs in flux density units indicate a spectral shape similar to a log-normal distribution that typically peaks near ∼ 30 GHz (Dickinson et al. 2018). ...
We introduce a method for removing CMB and anomalous microwave emission (AME, or spinning dust) intensity signals at high to intermediate Galactic latitudes in temperature sky maps at frequencies roughly between 5 and 40 GHz. The method relies on the assumption of a spatially uniform combined dust (AME and thermal) rms spectral energy distribution for these regions, but is otherwise model independent. A difference map is produced from input maps at two different frequencies in thermodynamic temperature: the two frequencies are chosen such that the rms AME signal in the lower frequency (~5 - 40 GHz) map is equivalent to the thermal dust emission rms in the higher frequency (~95 - 230 GHz) map. Given the high spatial correlation between AME and thermal dust, the resulting difference map is dominated by synchrotron and free-free foreground components, and can thus provide useful insight into the morphology and possible spectral variations of these components at high latitudes. We show examples of these difference maps obtained with currently available WMAP and Planck data and demonstrate the efficacy of CMB and dust mitigation using this method. We also use these maps, in conjunction with Haslam 408 MHz and WHAM H-alpha observations, to form an estimate of the diffuse synchrotron spectral index in temperature on degree scales. The hybrid analysis approach we describe is advantageous in situations where frequency coverage is insufficient to break spectral degeneracies between AME and synchrotron.
... An alternative model based on thermal emission from amorphous dust grains is also able to reproduce the AME microwave bump in total intensity (Jones 2009;Nashimoto et al. 2020). For a more detailed and complete review on models and observational status of AME, see Dickinson et al. (2018). ...
This work focuses on the study of the AME, an important emission mechanism between 10 and 60 GHz whose polarization properties are not yet fully understood, and is therefore a potential contaminant for future CMB polarization observations. We use new QUIJOTE-MFI maps 11, 13, 17 and 19 GHz, together with other public ancillary data including WMAP and Planck, to study the polarization properties of the AME in three Galactic regions: rho-Ophiuchi, Perseus and W43. We have obtained the SEDs for those three regions over the frequency range 0.4-3000 GHz, both in intensity and polarization. The intensity SEDs are well described by a combination of free-free emission, thermal dust, AME and CMB anisotropies. In polarization, we extracted the flux densities using all available data between 11 and 353 GHz. We implemented an improved intensity-to-polarization leakage correction that has allowed for the first time to derive reliable polarization constraints well below the 1% level from Planck-LFI data. A frequency stacking of maps in the range 10-60 GHz has allowed us to reduce the statistical noise and to push the upper limits on the AME polarization level. We have obtained upper limits on the AME polarization fraction of order <1% (95% confidence level) for the three regions. In particular we get Pi_AME < 1.1% (at 28.4 GHz), Pi_AME < 1.1% (at 22.8 GHz) and Pi_AME < 0.28% (at 33 GHz) in rho-Ophiuchi, Perseus and W43 respectively. At the QUIJOTE 17 GHz frequency band, we get Pi_AME< 5.1% for rho-Ophiuchi, Pi_AME< 3.5% for Perseus and Pi_AME< 0.85% for W43. Our final upper limits derived using the stacking procedure are Pi_AME < 0.58% for rho-Ophiuchi, Pi_AME < 1.64% for Perseus and Pi_AME < 0.31% for W43. Altogether, these are the most stringent constraints to date on the AME polarization fraction of these three star-forming regions.
... The 22-44 GHz spectral profile in Figure 3 appears similar to a combination of the Rayleigh-Jeans tail of the standard thermal emission of grown dust (see Hildebrand 1983) and the anomalous microwave emission (AME; for a review, see Dickinson et al. 2018). In the following discussion, we consider the possibility of attributing the origin of AME to spinning nano-meter-sized dust (Draine & Hensley 2012;Hoang et al. 2018). ...
PDS 70 is a protoplanetary system that hosts two actively accreting gas giants, namely, PDS 70b and PDS 70 c. The system has a ∼60–100 au dusty ring that has been resolved by the Atacama Large Millimeter/Submillimeter Array (ALMA), along with circumplanetary disks around the two gas giants. Here, we report the first Karl G. Jansky Very Large Array (JVLA) Q - (40–48 GHz), Ka - (29–37 GHz), K - (18–26 GHz), and X - (8–12 GHz) bands' continuum observations, and the complementary ALMA Bands 3 (∼98 GHz) and 4 (∼145 GHz) observations towards PDS 70. The dusty ring appears azimuthally asymmetric in our ALMA images. We obtained firm detections at Ka and K bands without spatially resolving the source; we obtained a marginal detection at Q band, and no detection at X band. The spectral indices ( α ) are 5 ± 1 at 33–44 GHz and 0.6 ± 0.2 at 22–33 GHz. At 10–22 GHz, the conservative lower limit of α is 1.7. The 33–44 GHz flux density is likely dominated by the optically thin thermal emission of grown dust with ≳1 mm maximum grain sizes, which may be associated with the azimuthally asymmetric substructure induced by planet–disk interaction. Since PDS 70 was not detected at X band, we found it hard to explain the low spectral index at 22–33 GHz only with free–free emission. Hence, we attribute the dominant emission at 22–33 GHz to the emission of spinning nano-meter-sized dust particles, while free–free emission may partly contribute to emission at this frequency range. In some protoplanetary disks, the emission of spinning nano-meter-sized dust particles may resemble the 20–50 GHz excess in the spectra of millimeter-sized dust. The finding of strong continuum emission of spinning nano-meter-sized particles can complicate the procedure of constraining the properties of grown dust. Future high resolution, multifrequency JVLA/Next Generation Very Large Array and Square Kilometer Array observations may shed light on this issue.
... The 22-44 GHz spectral profile in Figure 3 appears similar to a combination of the Rayleigh-Jeans tail of the standard thermal emission of grown dust (c.f. Hildebrand 1983) and the anomalous microwave emission (AME; for a review see Dickinson et al. 2018). In the following discussion, we consider the possibility of attributing the origin of AME to spinning nanometer-sized dust (Draine & Hensley 2012;Hoang et al. 2018). ...
PDS~70 is a protoplanetary system that hosts two actively accreting gas giants, namely PDS~70b and PDS~70c. The system has a 60--100 au dusty ring that has been resolved by ALMA, along with circumplanetary disks around the two gas giants. Here we report the first JVLA Q (40--48 GHz), Ka (29--37 GHz), K (18--26 GHz), and X (8--12 GHz) bands continuum observations, and the complementary ALMA Bands 3 (98 GHz) and 4 (145 GHz) observations towards PDS~70. The dusty ring appears azimuthally asymmetric in our ALMA images. We obtained firm detections at Ka and K bands without spatially resolving the source; we obtained a marginal detection at Q band, and no detection at X band. The spectral indices () are 51 at 33--44 GHz and 0.60.2 at 22--33 GHz. At 10--22 GHz, the conservative lower limit of is 1.7. The 33--44 GHz flux density is likely dominated by the optically thin thermal emission of grown dust with 1 mm maximum grain sizes, which may be associated with the azimuthally asymmetric substructure induced by planet-disk interaction. Since PDS~70 was not detected at X band, we found it hard to explain the low spectral index at 22--33 GHz only with free-free emission. Hence, we attribute the dominant emission at 22--33 GHz to the emission of spinning nanometer-sized dust particles, while free-free emission may partly contribute to emission at this frequency range. In some protoplanetary disks, the emission of spinning nanometer-sized dust particles may resemble the 20--50 GHz excess in the spectra of millimeter-sized dust. The finding of strong continuum emission of spinning nanometer-sized particles can complicate the procedure of constraining the properties of grown dust. Future high-resolution, multi-frequency JVLA/ngVLA and SKA observations may shed light on this issue.
... Simultaneously, we estimated Q(H 0 ) using radio emissions, assuming that they originated solely from H II regions (Murphy et al. 2010(Murphy et al. , 2011(Murphy et al. , 2012. Figure 10 shows one-to-one comparison between radio-based Q(H 0 ) and Q(H 0 ) based on other tracers, including 24 μm, total IR, and IR+FUV. The production rates based on the radio emission were measured at three different frequencies: the peak frequency of AME measured in this study (left panel); 30 GHz, at which several studies found the peak of AME (Dickinson et al. 2018) (middle panel); and 5 GHz, which is unlikely to be associated with AME (right panel). If radio emissions primarily originate from the H II region, radio-based Q(H 0 ) should be more or less consistent with Q(H 0 ) from other tracers. ...
... PAHs and nanodust play a key role in galaxy evolution because they govern gas heating and cooling, and chemical properties. More observations of AME (frequency range 10-100 GHz) toward galaxies are required for understanding the nature of AME and its carrier (Dickinson et al. 2018). Accurate characterization of AME is also vital for the accurate determination of star formation in galaxies using radio observations that are believed to be dominated by free-free and synchrotron emission. ...
We present the results of the single-dish observations using the Korean VLBI Network to search for anomalous microwave emission (AME) in nearby galaxies. The targets were selected from ‘Mapping the dense molecular gas in the strongest star-forming galaxies' (MALATANG), a legacy survey project of the James Clerk Maxwell Telescope. The MALATANG galaxies are good representatives of local galaxies with enhanced nuclear activity associated with star formation and/or active galactic nuclei (AGNs), providing IR-bright galaxy samples; thus, they are good candidates for AME hosts. Combining with ancillary data, we investigated the radio–IR spectral energy distribution (SED), while searching for AME signals in five galaxies. The AME in NGC 2903 was well detected at a significant confidence level, whereas that in NGC 2146 and M82 was marginal. NGC 1068 and Arp 299 indicated no significant hints, and we provide upper limits for the AME. The best-fit SED exhibited local peaks of the AME components at higher frequencies and with stronger peak fluxes than those in previous studies. This suggested that AME originates from denser environments such as molecular clouds or photodissociation regions rather than warm neutral/ionized medium as commonly suggested by previous studies. Further, our AME-detected targets were observed to exhibit higher specific star formation rates than the other extragalactic AME hosts. Furthermore, AME favored starburst galaxies among our sample rather than AGN hosts. Consequently, this might imply that AGNs are excessively harsh environments for tiny dust to survive.
... Neither are its polarization properties well understood yet, although observations both on compact regions at angular scales of 1 • or below (e.g., López-Caraballo et al. 2011;Dickinson et al. 2011;Génova-Santos et al. 2015, 2017 and on large angular scales (Macellari et al. 2011;Herman et al. 2022) indicate that its polarization fraction should be below 5%. See Dickinson et al. (2018) for a detailed review on AME. ...
... Both values are lower than those previously found in several other works (see e.g. Table 3 of Dickinson et al. 2018), but the AME emissivity can show large variations (Davies et al. 2006 found variations as large as a factor 2, for example). Those variations would probably be embedded within the integrated spectrum of the galaxy, effectively decreasing the AME emissivity value with respect to that found in compact sources. ...
The Andromeda Galaxy (M31) is the Local Group galaxy that is most similar to the Milky Way (MW). The similarities between the two galaxies make M31 useful for studying integrated properties common to spiral galaxies. We use the data from the recent QUIJOTE-MFI Wide Survey, together with new raster observations focused on M31, to study its integrated emission. The addition of raster data improves the sensitivity of QUIJOTE-MFI maps by almost a factor 3. Our main interest is to confirm if anomalous microwave emission (AME) is present in M31, as previous studies have suggested. To do so, we built the integrated spectral energy distribution of M31 between 0.408 and 3000 GHz. We then performed a component separation analysis taking into account synchrotron, free-free, AME and thermal dust components. AME in M31 is modelled as a log-normal distribution with maximum amplitude, AAME, equal to 1.03 ± 0.32 Jy. It peaks at νAME = 17.2 ± 3.2 GHz with a width of WAME = 0.58 ± 0.16. Both the Akaike and Bayesian Information Criteria find the model without AME to be less than 1% as probable as the one taking AME into consideration. We find that the AME emissivity per 100 μm intensity in M31 is ||K/(MJy/sr), similar to that of the MW. We also provide the first upper limits for the AME polarization fraction in an extragalactic object. M31 remains the only galaxy where an AME measurement has been made of its integrated spectrum.
... Whereas the radio emission of SNRs is well explained by synchrotron radiation, the physical mechanism responsible for AME is still under discussion. Electric dipole radiation (ED, Draine & Lazarian 1998) from very small ( ≤ 10 3 atoms) rapidly rotating (∼ 1.5 × 10 10 s −1 ) dust grains in the ISM, known as spinning dust emission (SD), appears to reproduce the observations well (see the review by Dickinson et al. 2018, and references therein). However, other physical mechanisms such as magnetic dipole (MD) emission from thermal fluctuations in magnetic dust grains (Draine & Lazarian 1999;Draine & Hensley 2013) and thermal emission from amorphous dust grains (Nashimoto et al. 2020), have been invoked to explain the intensity of AME behaviour. ...
... However, other physical mechanisms such as magnetic dipole (MD) emission from thermal fluctuations in magnetic dust grains (Draine & Lazarian 1999;Draine & Hensley 2013) and thermal emission from amorphous dust grains (Nashimoto et al. 2020), have been invoked to explain the intensity of AME behaviour. The observational polarization properties of AME, however, are still being debated, the only constraints suggesting weak or negligible polarization (Rubiño- Martín et al. 2012a;Dickinson et al. 2018). Predictions from the SD yield a polarization fraction Π AME ≤ 1% at 20 GHz (for grains aligned via resonance paramagnetic relaxation, Lazarian & Draine 2000), and significantly unpolarized levels where there is quantum alignment suppression (≪1%, Draine & Hensley 2016). ...
We use the new QUIJOTE-MFI wide survey (11, 13, 17 and 19 GHz) to produce spectral energy distributions (SEDs), on an angular scale of 1 deg, of the supernova remnants (SNRs) CTB 80, Cygnus Loop, HB 21, CTA 1, Tycho and HB 9. We provide new measurements of the polarized synchrotron radiation in the microwave range. For each SNR, the intensity and polarization SEDs are obtained and modelled by combining QUIJOTE-MFI maps with ancillary data. In intensity, we confirm the curved power law spectra of CTB 80 and HB 21 with a break frequency at 2.0 GHz and 5.0 GHz respectively; and spectral indices respectively below and above the spectral break of and for CTB 80, and and for HB 21. In addition, we provide upper limits on the Anomalous Microwave Emission (AME), suggesting that the AME contribution is negligible towards these remnants. From a simultaneous intensity and polarization fit, we recover synchrotron spectral indices as flat as , and the whole sample has a mean and scatter of . The polarization fractions have a mean and scatter of \%. When combining our results with the measurements from other QUIJOTE studies of SNRs, we find that radio spectral indices are flatter for mature SNRs, and particularly flatter for CTB 80 () and HB 21 (). In addition, the evolution of the spectral indices against the SNRs age is modelled with a power-law function, providing an exponent and amplitude (normalised at 10 kyr), which are conservative with respect to previous studies of our Galaxy and the Large Magellanic Cloud.
