scholarly journals Investigation of the origin of the anomalous microwave emission in Lambda Orionis

2019 ◽  
Author(s):  
Aaron C Bell ◽  
Takashi Onaka ◽  
Frédéric Galliano ◽  
Ronin Wu ◽  
Yasuo Doi ◽  
...  
Keyword(s):  
Interstellar Dust ◽  
Spectral Energy Distribution ◽  
Dust Emission ◽  
Infrared Camera ◽  
Detailed Comparison ◽  
Peak Frequency ◽  
Microwave Emission ◽  
Observational Cosmology ◽  
Spectral Energy ◽  
Dust Mass

AbstractThe anomalous microwave emission (AME) still lacks a conclusive explanation. This excess of emission, roughly between 10 and 50 GHz, tends to defy attempts to explain it as synchrotron or free–free emission. The overlap with frequencies important for cosmic microwave background explorations, combined with a strong correlation with interstellar dust, drive cross-disciplinary collaboration between interstellar medium and observational cosmology. The apparent relationship with dust has prompted a “spinning dust” hypothesis. The typical peak frequency range of the AME profile implicates spinning grains on the order of 1 nm. This points to polycyclic aromatic hydrocarbons (PAHs). We use data from the AKARI/Infrared Camera (IRC), due to its thorough PAH-band coverage, to compare AME from the Planck Collaboration astrophysical component separation product with infrared dust emission in the λ Orionis AME-prominent region. We look also at infrared dust emission from other mid-infrared and far-infrared bands. The results and discussion contained here apply to an angular scale of approximately 1°. We find that dust mass certainly correlates with AME, and that PAH-related emission in the AKARI/IRC 9 μm band correlates slightly more strongly. Using hierarchical Bayesian inference and full-dust spectral energy distribution (SED) modeling we argue that AME in λ Orionis correlates more strongly with PAH mass than with total dust mass, lending support for a spinning PAH hypothesis within this region. We emphasize that future efforts to understand AME should focus on individual regions, and a detailed comparison of the PAH features with the variation of the AME SED.

scholarly journals Dust properties and star formation of approximately a thousand local galaxies

2019 ◽  
Vol 631 ◽  
pp. A38 ◽  
Author(s):  
S. Lianou ◽  
P. Barmby ◽  
A. A. Mosenkov ◽  
M. Lehnert ◽  
O. Karczewski
Keyword(s):  
Star Formation ◽  
Spectral Energy Distribution ◽  
Dust Emission ◽  
Distribution Functions ◽  
Spectral Energy ◽  
Emission Properties ◽  
Galaxy Type ◽  
Dust Mass ◽  
The Galaxy ◽  
Stellar Masses

Aims. We derived the dust properties for 753 local galaxies and examine how these relate to some of their physical properties. We present the derived dust emission properties, including model spectral energy distribution (SEDs), star formation rates (SFRs) and stellar masses, as well as their relations. Methods. We modelled the global dust-SEDs for 753 galaxies, treated statistically as an ensemble within a hierarchical Bayesian dust-SED modelling approach, so as to derive their infrared (IR) emission properties. To create the observed dust-SEDs, we used a multi-wavelength set of observations, ranging from near-IR to far-IR-to-submillimeter wavelengths. The model-derived properties are the dust masses (Mdust), the average interstellar radiation field intensities (Uav), the mass fraction of very small dust grains (“QPAH” fraction), as well as their standard deviations. In addition, we used mid-IR observations to derive SFR and stellar masses, quantities independent of the dust-SED modelling. Results. We derive distribution functions of the properties for the galaxy ensemble and as a function of galaxy type. The mean value of Mdust for the early-type galaxies (ETGs) is lower than that for the late-type and irregular galaxies (LTGs and Irs, respectively), despite ETGs and LTGs having stellar masses spanning across the whole range observed. The Uav and “QPAH” fraction show no difference among different galaxy types. When fixing Uav to the Galactic value, the derived “QPAH” fraction varies across the Galactic value (0.071). The specific SFR increases with galaxy type, while this is not the case for the dust-specific SFR (SFR/Mdust), showing an almost constant star formation efficiency per galaxy type. The galaxy sample is characterised by a tight relationship between the dust mass and the stellar mass for the LTGs and Irs, while ETGs scatter around this relation and tend towards smaller dust masses. While the relation indicates that Mdust may fundamentally be linked to M⋆, metallicity and Uav are the second parameter driving the scatter, which we investigate in a forthcoming work. We used the extended Kennicutt–Schmidt (KS) law to estimate the gas mass and the gas-to-dust mass ratio (GDR). The gas mass derived from the extended KS law is on average ∼20% higher than that derived from the KS law, and a large standard deviation indicates the importance of the average star formation present to regulate star formation and gas supply. The average GDR for the LTGs and Irs is 370, and including the ETGs gives an average of 550.

scholarly journals Modelling the spinning dust emission from LDN 1780

2020 ◽  
Vol 495 (1) ◽  
pp. 1122-1135 ◽  
Author(s):  
Matias Vidal ◽  
Clive Dickinson ◽  
S E Harper ◽  
Simon Casassus ◽  
A N Witt
Keyword(s):  
Angular Resolution ◽  
Spectral Energy Distribution ◽  
Dust Emission ◽  
Microwave Emission ◽  
Spectral Energy ◽  
Frequency Range ◽  
Polycyclic Aromatic ◽  
The Difference ◽  
Dust Grain ◽  
Sd Model

ABSTRACT We study the anomalous microwave emission (AME) in the Lynds Dark Nebula (LDN) 1780 on two angular scales. With publicly available data at an angular resolution of 1°, we studied the spectral energy distribution of the cloud in the 0.408–2997 GHz frequency range. The cloud presents a significant (>20σ) amount of AME, making it one of the clearest examples of AME on 1 ° scales, and its spectrum can be well fitted with a spinning dust (SD) model. We also find at these angular scales that the location of the peak of the emission at lower frequencies (23–70 GHz) differs from the location at the higher frequencies (90–3000 GHz) maps. In addition to the analysis on 1° angular scales, we present data from the Combined Array for Research in Millimeter-wave Astronomy (CARMA) at 31 GHz with an angular resolution of 2 arcmin, in order to study the origin of the AME in LDN 1780. We studied morphological correlations between the CARMA map and different infrared tracers of dust emission. We found that the best correlation is with the 70- μm template, which traces warm dust (T ∼ 50 K). Finally, we study the difference in radio emissivity between two locations within the cloud. We measured a factor of ≈6 difference in 31-GHz emissivity. We show that this variation can be explained, using the SD model, by a variation on the dust grain size distribution across the cloud, particularly changing the fraction of polycyclic aromatic hydrocarbon for a fixed total amount of carbon.

Detections of far-infrared [OIII] and dust emission in a galaxy at z = 8.312: Early metal enrichment in the heart of the reionization era

2019 ◽  
Vol 15 (S341) ◽  
pp. 211-215
Author(s):  
Y. Tamura ◽  
K. Mawatari ◽  
T. Hashimoto ◽  
A. K. Inoue ◽  
E. Zackrissonm ◽  
...  
Keyword(s):  
Spectral Energy Distribution ◽  
Dust Emission ◽  
Far Infrared ◽  
Continuum Emission ◽  
Spectral Energy ◽  
Star Forming ◽  
Stellar Component ◽  
Dust Mass ◽  
Infrared Spectral ◽  
Emissivity Model

AbstractWe present ALMA detection of the [O iii] 88 μm line and 850 μm dust continuum emission in a Y-dropout Lyman break galaxy, MACS0416_Y1. The [O iii] detection confirms the object with a spectroscopic redshift to be z = 8.3118±0.0003. The 850 μm continuum intensity (0.14 mJy) implies a large dust mass on the order of 4×106M⊙. The ultraviolet-to-far infrared spectral energy distribution modeling, where the [O iii] emissivity model is incorporated, suggests the presence of a young (τage ≍ 4 Myr), star-forming (SFR ≍ 60M⊙yr−1), and moderately metal-polluted (Z ≍ 0.2Z⊙) stellar component with a stellar mass of 3 × 108M⊙. An analytic dust mass evolution model with a single episode of star formation does not reproduce the metallicity and dust mass in ≍ 4 Myr, suggesting an underlying evolved stellar component as the origin of the dust mass.

scholarly journals Galactic Far-Infrared Diffuse Emission

2001 ◽  
Vol 204 ◽  
pp. 47-55
Author(s):  
François Boulanger ◽  
Jean-Philippe Bernard ◽  
Guilaine Lagache ◽  
Bertrand Stepnik
Keyword(s):  
Interstellar Dust ◽  
Spectral Energy Distribution ◽  
Dust Emission ◽  
Far Infrared ◽  
Spectral Energy ◽  
Molecular Gas ◽  
Diffuse Emission ◽  
Gas Emission ◽  
Present Understanding ◽  
Small Dust

We review the present understanding of the interstellar dust contribution to the far-IR (λ > 100 μm) sky emission. We show how the contribution from the distinct ISM components (HI, H2, HII gas) are identified and characterized through spatial correlation with gas emission lines. We discuss the spectral energy distribution of the emission from cirrus dust associated with diffuse HI gas and from colder dust associated with molecular gas. We relate the drop in dust emission temperature from the diffuse interstellar medium to molecular gas to an evolution of dust affecting both the abundance of small dust grains and the far-IR emissivity of large grains.

scholarly journals X-ray - Infrared relation of AGNs and search for highly obscured accretion in the AKARI NEP Field

2019 ◽  
Vol 15 (S341) ◽  
pp. 172-176
Author(s):  
Takamitsu Miyaji ◽  
Keyword(s):  
Spectral Energy Distribution ◽  
Dust Emission ◽  
Infrared Camera ◽  
Infrared Emission ◽  
Spectral Energy ◽  
Wide Field ◽  
X Rays ◽  
The North ◽  
Infrared Astronomical Satellite ◽  
Astronomical Satellite

AbstractThe infrared Astronomical Satellite AKARI conducted deep (∼0.4 deg2) and wide (∼ 5.4 deg2) surveys around the North Ecliptic Pole (NEP) with its InfraRed Camera (IRC) with nine filters continuously covering the 2–25 μm range. These photometric bands include three filters that fill the “ Spitzer gap” between the wavelength coverages of IRAC and MIPS. This unique feature has enabled us to make sensitive mid-infrared detection of AGN candidates at z∼1-2, based on the Spectral Energy Distribution (SED) fitting including hot dust emission in the AGN torus. This enables us to compare X-rays and the AGN torus component of the infrared emission to help us identify highly absorbed AGNs, including Compton-thick ones. We report our results of the Chandra observation of the AKARI NEP Deep Field and discuss the prospects for upcoming Spectrum-RG (eROSITA+ART-XC) on the AKARI Wide field.

scholarly journals Probing changes of dust properties along a chain of solar-type prestellar and protostellar cores in Taurus with NIKA

2017 ◽  
Vol 604 ◽  
pp. A52 ◽  
Author(s):  
A. Bracco ◽  
P. Palmeirim ◽  
Ph. André ◽  
R. Adam ◽  
P. Ade ◽  
...  
Keyword(s):  
Star Formation ◽  
Spectral Energy Distribution ◽  
Dust Emission ◽  
Class Ii ◽  
Spectral Energy ◽  
Relevant Parameter ◽  
Mass Star ◽  
Radial Temperature ◽  
Dust Temperature ◽  
Prestellar Cores

The characterization of dust properties in the interstellar medium is key for understanding the physics and chemistry of star formation. Mass estimates are crucial to determine gravitational collapse conditions for the birth of new stellar objects in molecular clouds. However, most of these estimates rely on dust models that need further observational constraints to capture the relevant parameter variations depending on the local environment: from clouds to prestellar and protostellar cores. We present results of a new study of dust emissivity changes based on millimeter continuum data obtained with the NIKA camera at the IRAM-30 m telescope. Observing dust emission at 1.15 mm and 2 mm allows us to constrain the dust emissivity index, β, in the Rayleigh-Jeans tail of the dust spectral energy distribution far from its peak emission, where the contribution of other parameters (i.e. dust temperature) is more important. Focusing on the Taurus molecular cloud, one of the most famous low-mass star-forming regions in the Gould Belt, we analyze the emission properties of several distinct objects in the B213 filament. This subparsec-sized region is of particular interest since it is characterized by a collection ofevolutionary stages of early star formation: three prestellar cores, two Class 0/I protostellar cores and one Class II object. We are therefore able to compare dust properties among a sequence of sources that likely derive from the same parent filament. By means of the ratio of the two NIKA channel maps, we show that in the Rayleigh-Jeans approximation, βRJ varies among the objects: it decreases from prestellar cores (βRJ ~ 2) to protostellar cores (βRJ ~ 1) and the Class II object (βRJ ~ 0). For one prestellar and two protostellar cores, we produce a robust study using available Herschel data to constrain the dust temperature of the sources. By using the Abel transform inversion technique we derive accurate radial temperature profiles that allow us to obtain radial β profiles. We find systematic spatial variations of β in the protostellar cores that are not observed in the prestellar core. While in the former case β decreases toward the center (with β varying between 1 and 2), in the latter it remains constant (β = 2.4 ± 0.3). Moreover, the dust emissivity index appears anticorrelated with the dust temperature. We discuss the implication of these results in terms of dust grain evolution between pre- and protostellar cores.

scholarly journals Thermal emission from the amorphous dust: An alternative possibility of the origin of the anomalous microwave emission

2019 ◽  
Vol 72 (1) ◽  
Author(s):  
Masashi Nashimoto ◽  
Makoto Hattori ◽  
Ricardo Génova-Santos ◽  
Frédérick Poidevin
Keyword(s):  
Interstellar Dust ◽  
Amorphous Materials ◽  
Thermal Emission ◽  
Far Infrared ◽  
Alternative Interpretation ◽  
Microwave Emission ◽  
Spectral Energy ◽  
Radiative Processes ◽  
Resonance Emission ◽  
Amorphous Silicate

Abstract Complete studies of the radiative processes of thermal emission from the amorphous dust from microwave through far-infrared wavebands are presented by taking into account, self-consistently for the first time, the standard two-level systems (TLS) model of amorphous materials. The observed spectral energy distributions (SEDs) for the Perseus molecular cloud (MC) and W 43 from microwave through far-infrared are fitted with the SEDs calculated with the TLS model of amorphous silicate. We have found that the model SEDs reproduce the observed properties of the anomalous microwave emission (AME) well. The present result suggests an alternative interpretation for the AME being carried by the resonance emission of the TLS of amorphous materials without introducing new species. Simultaneous fitting of the intensity and polarization SEDs for the Perseus MC and W 43 are also performed. The amorphous model reproduces the overall observed feature of the intensity and polarization SEDs of the Perseus MC and W 43. However, the model’s predicted polarization fraction of the AME is slightly higher than the QUIJOTE upper limits in several frequency bands. A possible improvement of our model to resolve this problem is proposed. Our model predicts that interstellar dust is amorphous materials with very different physical characteristics compared with terrestrial amorphous materials.

scholarly journals A NuSTAR view of powerful γ-ray loud blazars

2019 ◽  
Vol 627 ◽  
pp. A72 ◽  
Author(s):  
G. Ghisellini ◽  
M. Perri ◽  
L. Costamante ◽  
G. Tagliaferri ◽  
T. Sbarrato ◽  
...  
Keyword(s):  
Energy Distribution ◽  
Spectral Energy Distribution ◽  
Peak Frequency ◽  
High Energy ◽  
Spectral Energy ◽  
X Rays ◽  
X Ray ◽  
Γ Ray ◽  
The Universe ◽  
Jet Power

We observed three blazars at z >  2 with the NuSTAR satellite. These were detected in the γ-rays by Fermi/LAT and in the soft X-rays, but have not yet been observed above 10 keV. The flux and slope of their X-ray continuum, together with Fermi/LAT data allows us to estimate their total electromagnetic output and peak frequency. For some of them we were able to study the source in different states, and investigate the main cause of the different observed spectral energy distribution. We then collected all blazars at redshifts greater than 2 observed by NuSTAR, and confirm that these hard and luminous X-ray blazars are among the most powerful persistent sources in the Universe. We confirm the relation between the jet power and the disk luminosity, extending it at the high-energy end.

scholarly journals A thin shell of ionized gas as the explanation for infrared excess among classical Cepheids

2020 ◽  
Vol 633 ◽  
pp. A47 ◽  
Author(s):  
V. Hocdé ◽  
N. Nardetto ◽  
E. Lagadec ◽  
G. Niccolini ◽  
A. Domiciano de Souza ◽  
...  
Keyword(s):  
Thin Shell ◽  
Spectral Energy Distribution ◽  
Dust Emission ◽  
Spectral Energy ◽  
Ionized Gas ◽  
Infrared Excess ◽  
Interstellar Clouds ◽  
Classical Cepheids ◽  
Extragalactic Distance Scale ◽  
The Impact

Context. The infrared (IR) excess of classical Cepheids is seldom studied and poorly understood despite observational evidence and the potential for its contribution to induce systematics on the period-luminosity (PL) relation used in the calibration of the extragalactic distance scale. Aims. This study aims to understand the physical origin of the IR excess found in the spectral energy distribution (SED) of 5 Cepheids: RS Pup (P = 41.46d), ζ Gem (P = 10.15d), η Aql (P = 7.18d), V Cen (P = 5.49d) and SU Cyg (P = 3.85d). Methods. A time series of atmospheric models along the pulsation cycle were fitted to a compilation of data, including optical and near-IR photometry, Spitzer spectra (secured at a specific phase), interferometric angular diameters, effective temperature estimates, and radial velocity measurements. Herschel images in two bands were also analyzed qualitatively. In this fitting process, based on the SPIPS algorithm, a residual was found in the SED, whatever the pulsation phase, and for wavelengths larger than about 1.2 μm, which corresponds to the so-determined infrared excess of Cepheids. This IR excess was then corrected from interstellar medium absorption in order to infer the presence (or absence) of dust shells and was, ultimately, used in order to fit a model for a shell of ionized gas. Results. For all Cepheids, we find a continuum IR excess increasing up to approximately −0.1 magnitudes at 30 μm, which cannot be explained by a hot or cold dust model of CircumStellar Environment (CSE). However, a weak but significant dust emission at 9.7 μm is found for ζ Gem, η Aql and RS Pup, while clear interstellar clouds are seen in the Herschel images for V Cen and RS Pup. We show, for the first time, that the IR excess of Cepheids can be explained by free–free emission from a thin shell of ionized gas, with a thickness of ≃15% of the star radius, a mass of 10−9−10−7M⊙ and a temperature ranging between 3500 and 4500 K. Conclusions. The presence of a thin shell of ionized gas around Cepheids must be tested with interferometers operating in the visible or mid-IR, or using radio telescopes. The impact of such CSEs of ionized gas on the PL relation of Cepheids also calls for further investigation.

scholarly journals ISM Diagnostics: Dust

2012 ◽  
Vol 8 (S292) ◽  
pp. 259-266 ◽  
Author(s):  
Takashi Onaka
Keyword(s):  
Vibration Mode ◽  
Spectral Energy Distribution ◽  
Dust Emission ◽  
Diagnostic Methods ◽  
Spectral Energy ◽  
Significant Information ◽  
Physical Conditions ◽  
Band Emission ◽  
Small Grains ◽  
The Universe

AbstractInfrared (IR) observations provide significant information on the lifecycle of dust grains in the interstellar medium (ISM), which is crucial for the understanding of the evolution of matter in the universe. The IR spectral energy distribution (SED) of the dust emission tells us the relative abundance of sub-micron grains, very small grains, and carriers of the unidentified infrared (UIR) emission bands, since they emit the far-IR, the mid-IR, and the UIR bands from the near- to mid-IR, respectively. On the other hand, the UIR emission bands themselves offer a useful means to probe the physical conditions from which the band emission arises because each band is assigned to a specific C-H or C-C vibration mode and because its relative intensity should reflect the properties of the band carriers and the physical conditions of the environment. Here the two diagnostic methods using IR observations are briefly described together with examples of the observational results. Implications for the dust lifecycle are also discussed.

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