scholarly journals Three-dimensional maps of interstellar dust in the Local Arm: using Gaia, 2MASS, and APOGEE-DR14

2018 ◽  
Vol 616 ◽  
pp. A132 ◽  
Author(s):  
R. Lallement ◽  
L. Capitanio ◽  
L. Ruiz-Dern ◽  
C. Danielski ◽  
C. Babusiaux ◽  
...  
Keyword(s):  
Interstellar Dust ◽  
Large Scale ◽  
Galactic Plane ◽  
Large Fraction ◽  
Complex Structure ◽  
Dust Emission ◽  
Three Dimensional ◽  
Red Giants ◽  
Photometric Calibration ◽  
The One

Context. Gaia data and stellar surveys open the way to the construction of detailed 3D maps of the Galactic interstellar (IS) dust based on the synthesis of star distances and extinctions. Dust maps are tools of broad use, also for Gaia-related Milky Way studies. Aims. Reliable extinction measurements require very accurate photometric calibrations. We show the first step of an iterative process linking 3D dust maps and photometric calibrations, and improving them simultaneously. Methods. Our previous 3D map of nearby IS dust was used to select low-reddening SDSS/APOGEE-DR14 red giants, and this database served for an empirical effective temperature- and metallicity-dependent photometric calibration in the Gaia G and 2MASS Ks bands. This calibration has been combined with Gaia G-band empirical extinction coefficients recently published, G, J, and Ks photometry and APOGEE atmospheric parameters to derive the extinction of a large fraction of the survey targets. Distances were estimated independently using isochrones and the magnitude-independent extinction KJ−Ks. This new dataset has been merged with the one used for the earlier version of dust map. A new Bayesian inversion of distance-extinction pairs has been performed to produce an updated 3D map. Results. We present several properties of the new map. A comparison with 2D dust emission reveals that all large dust shells seen in emission at middle and high latitudes are closer than 300 pc. The updated distribution constrains the well-debated, X-ray bright North Polar Spur to originate beyond 800 pc. We use the Orion region to illustrate additional details and distant clouds. On the large scale the map reveals a complex structure of the Local Arm. Chains of clouds of 2–3 kpc in length appear in planes tilted by ≃15° with respect to the Galactic plane. A series of cavities oriented along a l ≃ 60–240° axis crosses the Arm. Conclusions. The results illustrate the ongoing synergy between 3D mapping of IS dust and stellar calibrations in the context of Gaia. Dust maps provide prior foregrounds for future calibrations appropriate to different target characteristics or ranges of extinction, allowing us in turn to increase extinction data and produce more detailed and extended maps.

scholarly journals The magnetic structure of our Galaxy: a review of observations

2008 ◽  
Vol 4 (S259) ◽  
pp. 455-466 ◽  
Author(s):  
JinLin Han
Keyword(s):  
Magnetic Fields ◽  
Magnetic Structure ◽  
Large Scale ◽  
Galactic Halo ◽  
Galactic Center ◽  
Galactic Plane ◽  
Galactic Disk ◽  
Dust Emission ◽  
Measure Data ◽  
Radio Sources

AbstractThe magnetic structure in the Galactic disk, the Galactic center and the Galactic halo can be delineated more clearly than ever before. In the Galactic disk, the magnetic structure has been revealed by starlight polarization within 2 or 3 kpc of the Solar vicinity, by the distribution of the Zeeman splitting of OH masers in two or three nearby spiral arms, and by pulsar dispersion measures and rotation measures in nearly half of the disk. The polarized thermal dust emission of clouds at infrared, mm and submm wavelengths and the diffuse synchrotron emission are also related to the large-scale magnetic field in the disk. The rotation measures of extragalactic radio sources at low Galactic latitudes can be modeled by electron distributions and large-scale magnetic fields. The statistical properties of the magnetized interstellar medium at various scales have been studied using rotation measure data and polarization data. In the Galactic center, the non-thermal filaments indicate poloidal fields. There is no consensus on the field strength, maybe mG, maybe tens of μG. The polarized dust emission and much enhanced rotation measures of background radio sources are probably related to toroidal fields. In the Galactic halo, the antisymmetric RM sky reveals large-scale toroidal fields with reversed directions above and below the Galactic plane. Magnetic fields from all parts of our Galaxy are connected to form a global field structure. More observations are needed to explore the untouched regions and delineate how fields in different parts are connected.

scholarly journals Recent Results from the Antares Neutrino Telescope

2019 ◽  
Vol 207 ◽  
pp. 01001
Author(s):  
Antoine Kouchner
Keyword(s):  
Galactic Plane ◽  
Large Fraction ◽  
Neutrino Flux ◽  
High Energy ◽  
Neutrino Telescope ◽  
Point Sources ◽  
Joint Analysis ◽  
Neutrino Source ◽  
Cosmic Neutrino ◽  
The One

Antares, the first undersea neutrino telescope, has been continuously operating since 2007 in the Mediterranean Sea. The transparency of the water allows for a very good angular resolution in the reconstruction of neutrino events of all flavors. This results in an unmatched sensitivity for neutrino source searches, in a large fraction of the Southern Sky, at TeV energies. As a consequence, Antares provides valuable constraints on the origin of the cosmic neutrino flux discovered by the IceCube Collaboration. Based on an all-flavor dataset spanning nine years of operation of the detector, the latest results of Antares searches for neutrino point sources, and for diffuse neutrino emission from the entire sky as well as from several interesting regions such as the Galactic Plane, are presented. Several results have been obtained through a joint analysis with the IceCube Collaboration. Concerning the multi-messenger program, the focus is made on the follow-up searches of IceCube alerts, in particular the one related to the TXS 0506+056 blazar, thought to be the first extragalactic high-energy neutrino source identified so far.

scholarly journals Observational signatures of eccentric Jupiters inside gas cavities in protoplanetary discs

2021 ◽  
Author(s):  
Clément Baruteau ◽  
Gaylor Wafflard-Fernandez ◽  
Romane Le Gal ◽  
Florian Debras ◽  
Andrés Carmona ◽  
...  
Keyword(s):  
Large Scale ◽  
Near Infrared ◽  
Scattered Light ◽  
Dust Emission ◽  
Three Dimensional ◽  
Continuum Emission ◽  
Integrated Intensity ◽  
Gas Cavity ◽  
Hydrodynamical Simulations ◽  
Small Dust

Abstract Predicting how a young planet shapes the gas and dust emission of its parent disc is key to constraining the presence of unseen planets in protoplanetary disc observations. We investigate the case of a 2 Jupiter mass planet that becomes eccentric after migrating into a low-density gas cavity in its parent disc. Two-dimensional hydrodynamical simulations are performed and post-processed by three-dimensional radiative transfer calculations. In our disc model, the planet eccentricity reaches ∼0.25, which induces strong asymmetries in the gas density inside the cavity. These asymmetries are enhanced by photodissociation and form large-scale asymmetries in 12CO J=3→2 integrated intensity maps. They are shown to be detectable for an angular resolution and a noise level similar to those achieved in ALMA observations. Furthermore, the planet eccentricity renders the gas inside the cavity eccentric, which manifests as a narrowing, stretching and twisting of iso-velocity contours in velocity maps of 12CO J=3→2. The planet eccentricity does not, however, give rise to detectable signatures in 13CO and C18O J=3→2 inside the cavity because of low column densities. Outside the cavity, the gas maintains near-circular orbits, and the vertically extended optically thick CO emission displays a four-lobed pattern in integrated intensity maps for disc inclinations $\gtrsim$ 30○. The lack of large and small dust inside the cavity in our model further implies that synthetic images of the continuum emission in the sub-millimetre, and of polarized scattered light in the near-infrared, do not show significant differences when the planet is eccentric or still circular inside the cavity.

scholarly journals Photometric Calibration and Large-Scale Clustering in the Universe

1994 ◽  
Vol 161 ◽  
pp. 295-300
Author(s):  
R. Fong ◽  
N. Metcalfe ◽  
T. Shanks
Keyword(s):  
Correlation Function ◽  
Large Scale ◽  
Three Dimensional ◽  
High Signal ◽  
Galaxy Surveys ◽  
Photometric Calibration ◽  
Peculiar Velocities ◽  
Redshift Surveys ◽  
Point Correlation ◽  
Point Correlation Function

The machine measurements of UK Schmidt plates have produced two very large galaxy surveys, the APM survey and the Edinburgh-Durham Southern Galaxy Catalogue (or COSMOS survey). These surveys can constrain the power on large scales of ≳ 10h −1 Mpc better than current redshift surveys, simply because such large numbers, ≳ 2 million galaxies to bJ ≤ 20.5, provide very high signal/noise in the estimated two-point correlation function for galaxies. Furthermore, the results for the three-dimensional galaxy two point correlation function, ξ(r), obtained from the measured projected function, ω(θ), should be quite robust for reasonable model number-redshift distributions, N(z), for these magnitude limits (see, e.g., Roche et al. 1993). Another clear advantage of measuring ω(θ) is that it is unaffected by the peculiar velocities of the galaxies, whereas they have an important effect on the corresponding ξ,(s) using galaxy redshift surveys.

scholarly journals Three-dimensional interstellar dust reddening maps of the Galactic plane

2018 ◽  
Vol 483 (4) ◽  
pp. 4277-4289 ◽  
Author(s):  
B-Q Chen ◽  
Y Huang ◽  
H-B Yuan ◽  
C Wang ◽  
D-W Fan ◽  
...  
Keyword(s):  
Interstellar Dust ◽  
Galactic Plane ◽  
Three Dimensional

scholarly journals Mapping the three-dimensional multi-band extinction and diffuse interstellar bands in the Milky Way with LAMOST

2013 ◽  
Vol 9 (S298) ◽  
pp. 240-245 ◽  
Author(s):  
H.-B. Yuan ◽  
X.-W. Liu ◽  
M.-S Xiang ◽  
Z.-Y. Huo ◽  
H.-H. Zhang ◽  
...  
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Wide Field ◽  
Stellar Spectra ◽  
Photometric Calibration ◽  
Diffuse Interstellar Bands ◽  
The Galaxy ◽  
Spectroscopic Database ◽  
Galactic Astronomy ◽  
Multi Band

AbstractWith modern large scale spectroscopic surveys, such as the SDSS and LSS-GAC, Galactic astronomy has entered the era of millions of stellar spectra. Taking advantage of the huge spectroscopic database, we propose to use a “standard pair" technique to a) Estimate multi-band extinction towards sightlines of millions of stars; b) Detect and measure the diffuse interstellar bands in hundreds of thousands SDSS and LAMOST low-resolution spectra; c) Search for extremely faint emission line nebulae in the Galaxy; and d) Perform photometric calibration for wide field imaging surveys. In this contribution, we present some results of applying this technique to the SDSS data, and report preliminary results from the LAMOST data.

scholarly journals What can large-scale magnetohydrodynamic numerical experiments tell us about coronal heating?

2015 ◽  
Vol 373 (2042) ◽  
pp. 20150055 ◽  
Author(s):  
H. Peter
Keyword(s):  
Magnetic Field ◽  
Numerical Experiments ◽  
Large Scale ◽  
Extreme Ultraviolet ◽  
Complex Structure ◽  
Three Dimensional ◽  
Upper Atmosphere ◽  
Good Representation ◽  
The Sun ◽  
Coronal Emission

The upper atmosphere of the Sun is governed by the complex structure of the magnetic field. This controls the heating of the coronal plasma to over a million kelvin. Numerical experiments in the form of three-dimensional magnetohydrodynamic simulations are used to investigate the intimate interaction between magnetic field and plasma. These models allow one to synthesize the coronal emission just as it would be observed by real solar instrumentation. Large-scale models encompassing a whole active region form evolving coronal loops with properties similar to those seen in extreme ultraviolet light from the Sun, and reproduce a number of average observed quantities. This suggests that the spatial and temporal distributions of the heating as well as the energy distribution of individual heat deposition events in the model are a good representation of the real Sun. This provides evidence that the braiding of fieldlines through magneto-convective motions in the photosphere is a good concept to heat the upper atmosphere of the Sun.

scholarly journals Infrared Background Starlight: Observations and Galaxy Models

1990 ◽  
Vol 139 ◽  
pp. 35-47
Author(s):  
G. G. Fazio ◽  
T. M. Dame ◽  
S. Kent
Keyword(s):  
Large Scale ◽  
Near Infrared ◽  
Galactic Disk ◽  
Dust Emission ◽  
Three Dimensional ◽  
Infrared Region ◽  
Global Scale ◽  
Three Dimensional Model ◽  
Infrared Telescope ◽  
The Galaxy

The near-infrared region of the spectrum is a particularly advantageous window for observing the distribution of old, evolved stars in the galactic disk and bulge. These stars are important because they provide an excellent tracer of the overall stellar mass distribution. At shorter wavelengths extinction is a serious problem, and at longer wavelengths the flux is dominated by dust emission. A summary of the large-scale diffuse near-infrared observations of the Galaxy is presented, as is a summary of the results obtained from these data on the structure of the galactic disk and bulge. The importance of combining CO and near-infrared maps of similar resolution to determine a three-dimensional model of galactic extinction is demonstrated. The Spacelab-2 Infrared Telescope (IRT) data are used in conjunction with a proposed galactic model to make preliminary measurements of the global scale parameters of the Galaxy.

scholarly journals INTERPRETATION OF THE LARGE-SCALE EMISSION FROM THE GALACTIC PLANE

1981 ◽  
Vol 96 ◽  
pp. 261-274
Author(s):  
S. Drapatz
Keyword(s):  
Gamma Radiation ◽  
Interstellar Dust ◽  
Large Scale ◽  
Galactic Plane ◽  
Galactic Disk ◽  
Point Sources ◽  
Infrared Astronomy ◽  
Electromagnetic Spectrum ◽  
Interstellar Gas ◽  
To Come

To obtain information on the large-scale structure of our Galaxy, one has to investigate the radiation in the short-wavelength and long-wavelength portion of the electromagnetic spectrum where attenuation throughout the whole galactic disk is very low: gamma-radiation on the one-hand side and infrared and radio radiation on the other side. But since most of the different modes of radiation are generated by interaction of two or more basic galactic constituents one derives only indirect information on a specific component. To come as close to a unique solution as possible the results of as many different spectral regions as possible should be combined. From this point of view it is very encouraging that infrared astronomy has been entering the field and will continue to contribute in the years to come. While gamma-radiation presents mainly information about the cosmic rays and the interstellar gas and radio astronomy about early-type stars and the interstellar gas, infrared astronomy has opened a new way to investigate a major fraction of the stellar population and the interstellar dust. The information is contained in the diffuse galactic emission, which is observed at low galactic latitudes with a field of view large enough to discriminate against point sources, i.e. the emission is averaged over typical dimensions of some 100 pc.

scholarly journals The dust in M31

2019 ◽  
Vol 489 (4) ◽  
pp. 5436-5452 ◽  
Author(s):  
A P Whitworth ◽  
K A Marsh ◽  
P J Cigan ◽  
J J Dalcanton ◽  
M W L Smith ◽  
...  
Keyword(s):  
Optical Depth ◽  
Interstellar Dust ◽  
Large Fraction ◽  
Dust Emission ◽  
Giant Molecular Clouds ◽  
Mean Values ◽  
Red Giant ◽  
Pm 10 ◽  
Ir Emission ◽  
Compact Sources

Abstract We have analysed Herschel observations of M31, using the ppmap procedure. The resolution of ppmap images is sufficient ($\sim 31\, {\rm pc}$ on M31) that we can analyse far-IR dust emission on the scale of giant molecular clouds. By comparing ppmap estimates of the far-IR emission optical depth at $300\, \mu {\rm m}\, (\tau _{{300}})$, and the near-IR extinction optical depth at $1.1\, \mu {\rm m}\, (\tau _{{1.1}})$ obtained from the reddening of Red Giant Branch (RGB) stars, we show that the ratio ${\cal R}^{\mathrm{ obs.}}_\tau \equiv \tau _{{1.1}}/\tau _{{300}}$ falls in the range $500\lesssim {\cal R}^{\mathrm{ obs.}}_\tau \lesssim 1500$. Such low values are incompatible with many commonly used theoretical dust models, which predict values of ${\cal R}^{\mathrm{ model}}_\kappa \equiv \kappa _{{1.1}}/\kappa _{{300}}$ (where κ is the dust opacity coefficient) in the range $2500\lesssim {\cal R}^{\mathrm{ model}}_\kappa \lesssim 4000$. That is, unless a large fraction, $\gtrsim 60{{\ \rm per\ cent}}$, of the dust emitting at $300\, \mu {\rm m}$ is in such compact sources that they are unlikely to intercept the lines of sight to a distributed population like RGB stars. This is not a new result: variants obtained using different observations and/or different wavelengths have already been reported by other studies. We present two analytic arguments for why it is unlikely that $\gtrsim 60{{\ \rm per\ cent}}$ of the emitting dust is in sufficiently compact sources. Therefore it may be necessary to explore the possibility that the discrepancy between observed values of ${\cal R}^{\mathrm{ obs.}}_\tau$ and theoretical values of ${\cal R}^{\mathrm{ model}}_\kappa$ is due to limitations in existing dust models. ppmap also allows us to derive optical-depth weighted mean values for the emissivity index, β ≡ −dln (κλ)/dln (λ), and the dust temperature, T, denoted ${\bar{\beta }}$ and ${\bar{T}}$. We show that, in M31, ${\cal R}^{\mathrm{ obs.}}_\tau$ is anticorrelated with ${\bar{\beta }}$ according to ${\cal R}^{\mathrm{ obs.}}_\tau \simeq 2042(\pm 24)-557(\pm 10){\bar{\beta }}$. If confirmed, this provides a challenging constraint on the nature of interstellar dust in M31.

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