Dust polarization modelling at large scale over the northern Galactic cap using EBHIS and Planck data

Context. Currently, detection of the primordial gravitational waves using the B-mode of cosmic microwave background (CMB) is primarily limited by our knowledge of the polarized microwave foreground emissions. Improvements of the foreground analysis are therefore necessary. As we revealed in an earlier paper, the E-mode and B-mode of the polarized foreground have noticeably different properties, both in morphology and frequency spectrum, suggesting that they arise from different physicalprocesses, and need to be studied separately. Aims. I study the polarized emission from Galactic loops, especially Loop I, and mainly focus on the following questions: Does the polarized loop emission contribute predominantly to the E-mode or B-mode? In which frequency bands and in which sky regions can the polarized loop emission be identified? Methods. Based on a well known result concerning the magnetic field alignment in supernova explosions, a theoretical expectation is established that the loop polarizations should be predominantly E-mode. In particular, the expected polarization angles of Loop I are compared with those from the real microwave band data of WMAP and Planck. Results and conclusions. The comparison between model and data shows remarkable consistency between the data and our expectations at all bands and for a large area of the sky. This result suggests that the polarized emission of Galactic Loop I is a major polarized component in all microwave bands from 23 to 353 GHz, and a considerable part of the polarized foreground likely originates from a local bubble associated with Loop I, instead of the far more distant Galactic emission. This result also provides a possible way to explain the E-to-B excess problem by contribution of the loops. Finally, this work may also provide the first geometrical evidence that the Earth was hit by a supernova explosion.

The Microwave Background Radiation

Symposium - International Astronomical Union ◽

10.1017/s0074180900240898 ◽

1990 ◽

Vol 139 ◽

pp. 333-343 ◽

Cited By ~ 1

Author(s):

G. De Zotti ◽

L. Danese ◽

L. Toffolatti ◽

A. Franceschini

Keyword(s):

Large Scale ◽

Background Radiation ◽

High Redshift ◽

Dust Emission ◽

Radio Sources ◽

Microwave Background ◽

Satisfactory Explanation ◽

X Ray ◽

Microwave Background Radiation ◽

X Ray Background

We review the data on the spectrum and isotropy of the microwave background radiation and the astrophysical processes that may produce spectral distortions and anisotropies. As yet no fully satisfactory explanation has been found for the submillimeter excess observed by Matsumoto et al. (1988). The most precise data at λ > 1 mm disagree with nonrelativistic comptonization models which match the excess. Distortions produced by a very hot intergalactic medium yielding the X-ray background do not fit the submillimeter data. Very special requirements must be met for the interpretation in terms of high-redshift dust emission to work.Reported anisotropies on scales of several degrees and of tens of arcsec may be produced, at least in part, by discrete sources. Because the best experiments at cm wavelengths are close to the confusion limit, they provide interesting information on the large-scale distribution of radio sources.

The Explorer of Diffuse Galactic Emission (EDGE)

Highlights of Astronomy ◽

10.1017/s1539299600017871 ◽

2005 ◽

Vol 13 ◽

pp. 971-971

Author(s):

R. F. Silverberg ◽

E. S. Cheng ◽

D. A. Cottingham ◽

D. J. Fixsen ◽

L. Knox ◽

...

Keyword(s):

Galaxy Evolution ◽

Large Scale ◽

Microwave Background ◽

Complementary Information ◽

Subsequent Evolution ◽

Galaxy Surveys ◽

Lyman Alpha ◽

Test Models ◽

Galactic Emission ◽

Infrared Background

The details of the formation of the first objects, stars and galaxies and their subsequent evolution remain a cosmological unknown. Few observational probes of these processes exist. The Cosmic Infrared Background (CIB) originates from this era and measurements of its anisotropy can provide information to test models of both galaxy evolution and the growth of primordial structure. Such measurements should provide a sensitive probe of the large-scale variation in protogalaxy density at redshifts, z ~ 0.5-3, while optical galaxy surveys provide complementary information at z < 0.5 and Lyman alpha absorption forest studies and Cosmic Microwave Background measurements add information at higher redshifts.

Of Cosmic Background Anisotropies

Symposium - International Astronomical Union ◽

10.1017/s007418090010991x ◽

1996 ◽

Vol 168 ◽

pp. 31-44

Author(s):

G.F. Smoot

Keyword(s):

Large Scale ◽

Thermal Emission ◽

Big Bang ◽

Microwave Background ◽

The Standard Model ◽

The Big Bang ◽

The Universe ◽

Fundamental Physical ◽

Large Scale Structure Formation

Observations of the Cosmic Microwave Background (CMB) Radiation have put the standard model of cosmology, the Big Bang, on firm footing and provide tests of various ideas of large scale structure formation. CMB observations now let us test the role of gravity and General Relativity in cosmology including the geometry, topology, and dynamics of the Universe. Foreground galactic emissions, dust thermal emission and emission from energetic electrons, provide a serious limit to observations. Nevertheless, observations may determine if the evolution of the Universe can be understood from fundamental physical principles.

The Microwave Background Radiation: Recent Advances and New Problems

Highlights of Astronomy ◽

10.1017/s1539299600008650 ◽

1989 ◽

Vol 8 ◽

pp. 681-688 ◽

Cited By ~ 2

Author(s):

G. de Zotti ◽

L. Toffolatti

Keyword(s):

Large Scale ◽

Background Radiation ◽

Dust Emission ◽

Radio Sources ◽

Microwave Background ◽

Precise Data ◽

Intensity Measurements ◽

Planck Spectrum ◽

Microwave Background Radiation ◽

Source Confusion

AbstractThe substantially improved intensity measurements at wavelengths longward of the intensity peak of the microwave background are fully consistent with a Planck spectrum. The most precise data disagree with non-relativistic comptonization models for the large submillimeter excess observed by the Nagoya-Berkeley collaboration. The interpretation of such excess as dust emission at high redshifts also faces severe difficulties. Reported anisotropies on scales of several degrees and of tens of arcsec may be contributed, at least in part, by discrete sources. Just because the best experiments at cm wavelengths nave already got close to the source confusion limit, they also provide interesting information on the large scale distribution of radio sources. Polarimetry may be decisive in clarifying the origin of observed fluctuations.

Polarized thermal dust emission as seen by Planck : A comparison with MHD simulations and lessons from a toy model

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316004452 ◽

2015 ◽

Vol 11 (A29B) ◽

pp. 50-50

Author(s):

F. Levrier ◽

J. Neveu ◽

Keyword(s):

Magnetic Field ◽

Large Scale ◽

Thermal Emission ◽

Dust Emission ◽

Statistical Properties ◽

Random Component ◽

Mhd Turbulence ◽

Local Dispersion ◽

Mhd Simulations ◽

Polarization Fraction

AbstractThe Planck satellite has mapped the polarized microwave sky (from 30 GHz to 353 GHz) with unprecedented sensitivity and angular resolution. This wealth of data yields the first complete map of polarized thermal emission from dust in our own Galaxy, shedding new light on the formation of dense cold structures within which new stars and planetary systems are born, under the combined effects of gravity, turbulence and magnetic fields. We present a statistical analysis of this polarized emission from nearby molecular clouds, with an emphasis on the evolution of the maximum polarization fraction observed as a function of column density, and on the anti-correlation between the polarization fraction and the local dispersion of polarization angles. To interpret this data, numerical simulations of anisotropic MHD turbulence underline the essential role played by the topology of the interstellar magnetic field, in particular its large-scale component. Indeed, the polarization of dust thermal emission at the scales observed by Planck is essentially related to the geometry of the magnetic field. Polarization fractions anti-correlate with column densities, which may be due to a succession of variously polarized structures on the line of sight. They also anti-correlate with the local dispersion of polarization angles. These features are well reproduced by MHD simulations of the diffuse ISM, with comparable correlation coefficients. As an extension to this work published in Planck Intermediate Results XX (A&A, 576, 105, 2015), the statistical properties of the random component of the interstellar magnetic field are explored using a toy model of the turbulent magnetized ISM based on fractional Brownian motion (fBm) fields. A least-squares analysis to retrieve the statistical properties of the interstellar magnetic field from Planck observations is pursued. Application of this method on the toy model shows good promise, and we are currently working towards its application on Planck data.

ALMA resolves the remarkable molecular jet and rotating wind in the extremely radio-quiet galaxy NGC 1377

Astronomy and Astrophysics ◽

10.1051/0004-6361/202038282 ◽

2020 ◽

Vol 640 ◽

pp. A104

Author(s):

S. Aalto ◽

N. Falstad ◽

S. Muller ◽

K. Wada ◽

J. S. Gallagher ◽

...

Keyword(s):

Column Density ◽

Feedback Loop ◽

Large Scale ◽

Dust Emission ◽

Average Diameter ◽

High Mass ◽

Molecular Gas ◽

Vibrationally Excited ◽

Gas Dispersion ◽

Moderate Growth

Submillimetre and millimetre line and continuum observations are important in probing the morphology, column density, and dynamics of the molecular gas and dust around obscured active galactic nuclei (AGNs) and their mechanical feedback. With very high-resolution (0.″02 × 0.″03 (2 × 3 pc)) ALMA 345 GHz observations of CO 3–2, HCO+ 4–3, vibrationally excited HCN 4–3 ν2 = 1f, and continuum we have studied the remarkable, extremely radio-quiet, molecular jet and wind of the lenticular galaxy NGC 1377. The outflow structure is resolved, revealing a 150 pc long, clumpy, high-velocity (∼600 km s−1), collimated molecular jet where the molecular emission is emerging from the spine of the jet with an average diameter of 3–7 pc. The jet widens to 10–15 pc about 25 pc from the centre, which is possibly due to jet-wind interactions. A narrow-angle (50°–70°), misaligned and rotating molecular wind surrounds the jet, and both are enveloped by a larger-scale CO-emitting structure at near-systemic velocity. The jet and narrow wind have steep radial gas excitation gradients and appear turbulent with high gas dispersion (σ > 40 km s−1). The jet shows velocity reversals that we propose are caused by precession, or more episodic directional changes. We discuss the mechanisms powering the outflow, and we find that an important process for the molecular jet and narrow wind is likely magneto-centrifugal driving. In contrast, the large-scale CO-envelope may be a slow wind, or cocoon that stems from jet-wind interactions. An asymmetric, nuclear r ∼ 2 pc dust structure with a high inferred molecular column density N(H2) ≃1.8 × 1024 cm−2 is detected in continuum and also shows compact emission from vibrationally excited HCN. The nuclear dust emission is hot (Td > 180 K) and its luminosity is likely powered by a buried AGN. The lopsided structure appears to be a warped disk, which is responsible for a significant part of the nuclear obscuration and possibly formed as a result of uneven gas inflows. The dynamical mass inside r = 1.4 pc is estimated to 9−3+2 × 106 M⊙, implying that the supermassive black hole (SMBH) has a high mass with respect to the stellar velocity dispersion of NGC 1377. We suggest that the SMBH of NGC 1377 is currently in a state of moderate growth, at the end of a more intense phase of accretion and also evolving from a state of more extreme nuclear obscuration. The nuclear growth may be fuelled by low-angular momentum gas inflowing from the gas ejected in the molecular jet and wind. Such a feedback-loop of cyclic outflows and central accretion could explain why there is still a significant reservoir of molecular gas in this ageing, lenticular galaxy. A feedback-loop would be an effective process in growing the nuclear SMBH and thus would constitute an important phase in the evolution of NGC 1377. This also invites new questions as to SMBH growth processes in obscured, dusty galaxies.

Polarized thermal dust emission as seen by Planck : A comparison with MHD simulations and lessons from a toy model

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316008115 ◽

2015 ◽

Vol 11 (S315) ◽

Author(s):

F. Levrier ◽

J. Neveu ◽

Keyword(s):

Magnetic Field ◽

Large Scale ◽

Angular Resolution ◽

Thermal Emission ◽

Dust Emission ◽

Random Component ◽

Mhd Turbulence ◽

Local Dispersion ◽

Mhd Simulations ◽

Polarization Fraction

AbstractThe Planck satellite has mapped the polarized microwave sky (from 30 GHz to 353 GHz) with unprecedented sensitivity and angular resolution. This wealth of data yields the first complete map of polarized thermal emission from dust in our own Galaxy, shedding new light on the formation of dense cold structures within which new stars and planetary systems are born, under the combined effects of gravity, turbulence and magnetic fields. We present a statistical analysis of this polarized emission from nearby molecular clouds, with an emphasis on the evolution of the maximum polarization fraction observed as a function of column density, and on the anti-correlation between the polarization fraction and the local dispersion of polarization angles. To interpret this data, numerical simulations of anisotropic MHD turbulence underline the essential role played by the topology of the interstellar magnetic field, in particular its large-scale component. As an extension to this work published in Planck Intermediate Results XX (A&A, 576, 105, 2015), the statistical properties of the random component of the interstellar magnetic field are explored using a toy model based on fractional Brownian motion (fBm) fields.

Modelling and simulation of large-scale polarized dust emission over the southern Galactic cap using the GASS Hi data

Astronomy and Astrophysics ◽

10.1051/0004-6361/201629829 ◽

2017 ◽

Vol 601 ◽

pp. A71 ◽

Cited By ~ 20

Author(s):

T. Ghosh ◽

F. Boulanger ◽

P. G. Martin ◽

A. Bracco ◽

F. Vansyngel ◽

...

Keyword(s):

Magnetic Field ◽

Column Density ◽

Large Scale ◽

Dust Emission ◽

Neutral Medium ◽

Limiting Factor ◽

Galactic Latitude ◽

Galactic Magnetic Field ◽

Emission Data ◽

Field Orientation

The Planck survey has quantified polarized Galactic foregrounds and established that they are a main limiting factor in the quest for the cosmic microwave background B-mode signal induced by primordial gravitational waves during cosmic inflation. Accurate separation of the Galactic foregrounds therefore binds this quest to our understanding of the magnetized interstellar medium. The two most relevant empirical results from analysis of Planck data are line of sight depolarization arising from fluctuations of the Galactic magnetic field orientation and alignment of filamentary dust structures with the magnetic field at high Galactic latitude. Furthermore, Planck and H I emission data in combination indicate that most of the filamentary dust structures are in the cold neutral medium. The goal of this paper is to test whether these salient observational results, taken together, can account fully for the statistical properties of the dust polarization over a selected low column density region comprising 34% of the southern Galactic cap (b ≤ −30°). To do this, we construct a dust model that incorporates H I column density maps as tracers of the dust intensity structures and a phenomenological description of the Galactic magnetic field. By adjusting the parameters of the dust model, we were able to reproduce the Planck dust observations at 353GHz in the selected region. Realistic simulations of the polarized dust emission enabled by such a dust model are useful for testing the accuracy of component separation methods, studying non-Gaussianity, and constraining the amount of decorrelation with frequency.

Occurrence and Molecular Variability of Kiwifruit Viruses in Actinidia deliciosa ‘Xuxiang’ in the Shaanxi Province of China

Plant Disease ◽

10.1094/pdis-09-18-1570-re ◽

2019 ◽

Vol 103 (6) ◽

pp. 1309-1318 ◽

Cited By ~ 4

Author(s):

Lei Zhao ◽

Wen Yang ◽

Yuanle Zhang ◽

Zhanmin Wu ◽

Qiao-Chun Wang ◽

...

Keyword(s):

Large Scale ◽

Primary Source ◽

Potato Virus X ◽

Shaanxi Province ◽

Multiple Infection ◽

First Report ◽

Molecular Variability ◽

Large Scale Survey ◽

Actinidia Spp ◽

Main Producer

Kiwifruit (Actinidia spp.) is an economically substantial fruit crop with China the main producer. China is the primary source of wild kiwifruit and the largest producer of kiwifruit in terms of both production and planting area, and Shaanxi province is the largest kiwifruit producer in China. Previous studies reported presence of kiwifruit viruses in Actinidia chinensis. In this study, six viruses were identified in kiwifruit ‘Xuxiang’ (A. deliciosa) in Shaanxi, China. The incidence, distribution, and genetic diversity of these viruses were studied. The results showed that Actinidia virus A (AcVA), Actinidia virus B (AcVB), Actinidia chlorotic ringspot-associated virus (AcCRaV), cucumber mosaic virus (CMV), apple stem grooving virus (ASGV), and potato virus X (PVX) were the main viruses infecting Xuxiang kiwifruit in Shaanxi, China. Incidence of the various viruses with both single and multiple infection varied with different kiwifruit-growing counties. For single virus infection, the highest and the lowest numbers of samples infected were about 22 for AcCRaV and 0 for AcVB in Meixian out of 170 samples, 12 for AcVA and 0 for CMV in Zhouzhi out of 120 samples, 10 for AcVA and 0 for AcVB, AcCRaV, ASGV, PVX, and CMV in Yangling out of 70 samples, and 8 for AcCRaV and CMV and 0 for AcVA, AcVB, ASGV, and PVX in Hanzhong out of 80 samples, respectively. Samples which were multiply infected with two or more viruses were also detected. Analysis of the phylogenetic tree of these viruses showed some genetic variability in the AcVA, AcVB, and AcCRaV isolates of Shaanxi kiwifruit. There was no obvious molecular variation in the coat protein genes of ASGV, CMV, and PVX virus isolates from Shaanxi kiwifruit. The present study is the first large-scale survey of kiwifruit viruses in Shaanxi, China. To our knowledge, this is the first report of PVX infecting kiwifruit and the first report of molecular variability of AcVA, AcVB, and AcCRaV. These results provide important data for studying the genetic evolution of AcVA, AcVB, AcCRaV, ASGV, CMV, and PVX.