scholarly journals THE SINO-GERMAN λ6 CM POLARIZATION SURVEY OF THE GALACTIC PLANE: A SUMMARY

2013 ◽  
Vol 23 ◽  
pp. 82-91 ◽  
Author(s):  
J. L. HAN ◽  
W. REICH ◽  
X. H. SUN ◽  
X. Y. GAO ◽  
L. XIAO ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Interstellar Medium ◽  
Radio Telescope ◽  
Supernova Remnants ◽  
Galactic Plane ◽  
High Sensitivity ◽  
Hii Regions ◽  
Galactic Latitude ◽  
Galactic Longitude ◽  
Individual Objects

We have finished the λ6 cm polarization survey of the Galactic plane using the Urumqi 25 m radio telescope. It covers 10° ≤ l ≤ 230° in Galactic longitude and |b| ≤ 5° in Galactic latitude. The new polarization maps not only reveal new properties of the diffuse magnetized interstellar medium, but also are very useful for studying individual objects such as HII regions, which may act as Faraday screens with strong regular magnetic fields inside, and supernova remnants for their polarization properties and spectra. The high sensitivity of the survey enables us to discover two new SNRs G178.2–4.2 and G25.3–2.1 and a number of HII regions.

scholarly journals A Multi-Wavelength View of the XMM-Newton Galactic Plane

2014 ◽  
Vol 1 (1) ◽  
pp. 123-126
Author(s):  
Ada Nebot Gómez-Morán ◽  
Christian Motch
Keyword(s):  
Surface Density ◽  
Binary Systems ◽  
Galactic Plane ◽  
Galactic Centre ◽  
Galactic Latitude ◽  
X Ray ◽  
Model Predictions ◽  
Science Centre ◽  
Multi Wavelength ◽  
Galactic Longitude

We present an X-ray survey of the Galactic Plane conducted by the Survey Science Centre of the XMM-Newton satellite. The survey contains more than 1300 X-ray detections at low and intermediate Galactic latitudes and covering 4 deg<sup>2</sup> well spread in Galactic longitude. From a multi-wavelength analysis, using optical spectra and helped by optical and infrared photometry we identify and classify about a fourth of the sources. The observed surface density of soft X-ray (&lt;2 keV) sources decreases with Galactic latitude and although compatible with model predictions at first glance, presents an excess of stars, likely due to giants in binary systems. In the hard band (&gt;2 keV) the surface density of sources presents an excess with respect to the expected extragalactic contribution. This excess highly concentrates towards the direction of the Galactic Centre and is compatible with previous results from Chandra observations around the Galactic Centre. The nature of these sources is still unknown.

scholarly journals A Study of Low density Ionized Gas in the Galactic Plane

2002 ◽  
Vol 199 ◽  
pp. 335-338
Author(s):  
D. Anish Roshi ◽  
K. R. Anantharamaiah
Keyword(s):  
Radio Telescope ◽  
Radial Distribution ◽  
Angular Resolution ◽  
Galactic Plane ◽  
Hii Regions ◽  
Low Density ◽  
Ionized Gas ◽  
Star Forming ◽  
Star Forming Regions ◽  
Complete Survey

A complete survey of radio recombination lines (RRLs) near 327 MHz from the galactic plane (l = 330° − 0°-89°, b = 0°) was carried out using a section of the Ooty Radio Telescope (ORT) with an angular resolution of 2° × 2°. A subset of regions in the same area was observed using the whole telescope which has a beam of 2° × 6'. Hydrogen RRLs were detected in most of the positions that were observed. The lv diagram and radial distribution computed from the observed spectra and their comparison with other species in the galactic plane indicate that the low density gas detected in the survey is distributed similar to the star forming regions. For an assumed temperature of 7000 K, we estimate that the densities and sizes of the regions are in the range 1 — 10 cm−3 and 20 — 200 pc respectively. Our data suggests that the low density ionized gas is in the form of outer envelopes of normal HII regions.

scholarly journals Probing interstellar magnetic fields with Supernova remnants

2008 ◽  
Vol 4 (S259) ◽  
pp. 75-80 ◽  
Author(s):  
Roland Kothes ◽  
Jo-Anne Brown
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Supernova Remnants ◽  
Large Scale ◽  
Galactic Plane ◽  
Field Configuration ◽  
Large Scale Magnetic Field ◽  
Rotation Measure ◽  
Field Lines ◽  
The Magnetic Field

AbstractAs Supernova remnants expand, their shock waves are freezing in and compressing the magnetic field lines they encounter; consequently we can use Supernova remnants as magnifying glasses for their ambient magnetic fields. We will describe a simple model to determine emission, polarization, and rotation measure characteristics of adiabatically expanding Supernova remnants and how we can exploit this model to gain information about the large scale magnetic field in our Galaxy. We will give two examples: The SNR DA530, which is located high above the Galactic plane, reveals information about the magnetic field in the halo of our Galaxy. The SNR G182.4+4.3 is located close to the anti-centre of our Galaxy and reveals the most probable direction where the large-scale magnetic field is perpendicular to the line of sight. This may help to decide on the large-scale magnetic field configuration of our Galaxy. But more observations of SNRs are needed.

scholarly journals Extended Polarized Emission Structures in the Galactic Plane at 11 cm Wavelength

1990 ◽  
Vol 140 ◽  
pp. 63-64
Author(s):  
N. Junkes ◽  
E. Fürst ◽  
W. Reich
Keyword(s):  
Supernova Remnants ◽  
Spiral Structure ◽  
Galactic Plane ◽  
Radio Sources ◽  
Galactic Magnetic Field ◽  
Background Component ◽  
Polarized Emission ◽  
The Galaxy ◽  
Galactic Longitude ◽  
Thermal Background

Data from the Effelsberg Galactic plane survey at 11 cm wavelength have been used to produce a survey of polarized intensity in the first Galactic quadrant. Besides polarized sources (Supernova remnants and extragalactic objects) extended polarized emission features are visible, which are not connected to distinct radio sources. To decide whether these features reflect characteristics of the local field or the distant spiral structure of the Galaxy we performed an integration of polarized intensities as a function of Galactic longitude. An anticorrelation with the thermal background component suggests a distance of more than 6 kpc for some components of the polarized emission. This enables us to derive an upper limit for the uniform component of the Galactic magnetic field.

scholarly journals Atlas of Main-line OH Masers in the Galactic Longitude Range 3° to 60°

1983 ◽  
Vol 36 (3) ◽  
pp. 417 ◽  
Author(s):  
JL Caswell ◽  
RF Haynes
Keyword(s):  
Star Formation ◽  
Circular Polarization ◽  
Galactic Plane ◽  
Hii Regions ◽  
Main Line ◽  
Late Type ◽  
Circumstellar Shells ◽  
Many Sources ◽  
First Time ◽  
Galactic Longitude

We tabulate all 55 OH main-line masers discovered to date in the galactic plane between longitude 3� and 60�. For most of these we show current spectra, which have been taken with the Parkes 64 m radio telescope, in both senses of circular polarization on the 1665 MHz and/or 1667 MHz transitions; for some sources we give new position estimates, and several sources are reported for the first time. We discuss many sources individually and note that while most of the main-line OH masers probably pinpoint compact HII regions and sites of current star formation, a few appear to be unusual varieties occurring in circumstellar shells, possibly associated with late-type stars.

scholarly journals Search for and study of pulsars with the Nançay Radio Telescope

2017 ◽  
Vol 13 (S337) ◽  
pp. 386-387
Author(s):  
Franck Octau ◽  
Grégory Desvignes ◽  
Ismaël Cognard ◽  
David Champion ◽  
Patrick Lazarus ◽  
...  
Keyword(s):  
Interstellar Medium ◽  
Radio Telescope ◽  
Galactic Plane ◽  
Strong Field ◽  
Sampling Time ◽  
Current Status ◽  
Black Widow ◽  
Gravitation Wave ◽  
Tests Of Gravity

AbstractSince the discovery of the first pulsar in 1967, over 2500 pulsars have been discovered. Pulsars enable a broad range of studies: from the study of the properties of the interstellar medium and of pulsar magnetospheres to tests of gravity in the strong-field regime and the characterisation of the cosmological gravitation wave background. These reasons are the main drive for searching for more pulsars. A blind pulsar survey, named SPAN512, was initiated with the Nançay Radio Telescope in 2012. Conducted at 1.4 GHz with a sampling time of 64μs and 500-kHz frequency channels, SPAN512 was designed to search for fast and distant pulsars in the Galactic plane. Here we describe the current status of the survey and present the latest discovery, PSR J2055+3829, a 2.08-ms pulsar in a black widow system.

scholarly journals Models for Compact X-Ray Sources

1973 ◽  
Vol 55 ◽  
pp. 135-142 ◽  
Author(s):  
E. E. Salpeter
Keyword(s):  
Stellar Population ◽  
Galactic Plane ◽  
Theoretical Models ◽  
Black Body ◽  
Small Mass ◽  
Galactic Latitude ◽  
Strong Concentration ◽  
X Ray ◽  
Stellar Masses ◽  
Galactic Longitude

A statistical analysis of the UHURU catalogue of X-ray sources leads to the following conclusions. If the weak sources are omitted, there is a strong concentration to low galactic latitude but the absence of a strong background and the presence of some strong sources at low galactic longitude indicate an appreciable number of sources of luminosity L ∼ 104L⊙ in the vicinity of the ‘nuclear bulge’. This region generally suggests ‘stellar population II’ and therefore stars of small mass. However, there is some suggestion of a second class of sources, distributed in the galactic plane like ‘stellar population I’ and suggesting large stellar masses.There are three possible types of simple X-ray spectra, (a) optically thin bremsstrahlung, (b) black-body spectrum, and (c) power-law spectra. In this talk only theoretical models for type (a) are reviewed, including accretion, rotation and vibration for a white dwarf star and cocoons around a neutron star.

scholarly journals Magnetic Fields and the Interstellar Medium in Spiral Arms

1996 ◽  
Vol 171 ◽  
pp. 456-456
Author(s):  
M. Urbanik ◽  
M. Soida ◽  
R. Beck
Keyword(s):  
Magnetic Fields ◽  
Interstellar Medium ◽  
Radio Telescope ◽  
High Frequency ◽  
Spiral Galaxies ◽  
Total Power ◽  
Spiral Arms ◽  
Dust Lane ◽  
Radio Studies ◽  
Spiral Structures

We performed the high frequency radio studies of spiral galaxies using the 100 m MPIfR radio telescope at 10.55 GHz. Two objects: NGC 4254 and NGC 3627 possess perturbed spiral structures while two others, NGC 3521 and NGC 5055 are flocculent objects, lacking organized spiral patterns. NGC 3521 possesses also a peculiar dust lane. For NGC 4254, NGC 3627 and NGC 5055 deep polarization maps were made, for NGC 3521 the total power data only were analyzed (see Urbanik et al. 1989).

scholarly journals The High Time Resolution Universe surveys for pulsars and fast transients

2012 ◽  
Vol 8 (S291) ◽  
pp. 29-34 ◽  
Author(s):  
Michael J. Keith
Keyword(s):  
Radio Telescope ◽  
Time Resolution ◽  
Gamma Ray ◽  
Galactic Plane ◽  
High Time ◽  
Frequency Resolution ◽  
High Time Resolution ◽  
Galactic Latitude ◽  
Millisecond Pulsars ◽  
Bank System

AbstractThe High Time Resolution Universe survey for pulsars and transients is the first truly all-sky pulsar survey, taking place at the Parkes Radio Telescope in Australia and the Effelsberg Radio Telescope in Germany. Utilising multibeam receivers with custom built all-digital recorders the survey targets the fastest millisecond pulsars and radio transients on timescales of 64 μs to a few seconds. The new multibeam digital filter-bank system at has a factor of eight improvement in frequency resolution over previous Parkes multibeam surveys, allowing us to probe further into the Galactic plane for short duration signals. The survey is split into low, mid and high Galactic latitude regions. The mid-latitude portion of the southern hemisphere survey is now completed, discovering 107 previously unknown pulsars, including 26 millisecond pulsars. To date, the total number of discoveries in the combined survey is 135 and 29 MSPs These discoveries include the first magnetar to be discovered by it's radio emission, unusual low-mass binaries, gamma-ray pulsars and pulsars suitable for pulsar timing array experiments.

scholarly journals Radio Stars of the SKA

Universe ◽  
2021 ◽  
Vol 7 (5) ◽  
pp. 119
Author(s):  
Bin Yu ◽  
Albert Zijlstra ◽  
Biwei Jiang
Keyword(s):  
Radio Emission ◽  
Milky Way ◽  
Galactic Plane ◽  
High Sensitivity ◽  
Hii Regions ◽  
Be Stars ◽  
M Dwarfs ◽  
Ob Stars ◽  
5 Ghz ◽  
Radio Stars

Radio emission from stars can be used, for example, to study ionized winds or stellar flares. The radio emission is faint and studies have been limited to few objects. The Square Kilometer Array (SKA) brings a survey ability to the topic of radio stars. In this paper we investigate what the SKA can detect, and what sensitivity will be required for deep surveys of the stellar Milky Way. We focus on the radio emission from OB stars, Be stars, flares from M dwarfs, and Ultra Compact HII regions. The stellar distribution in the Milky Way is simulated using the Besançon model, and various relations are used to predict their radio flux. We find that the full SKA will easily detect all UltraCompact HII regions. At the limit of 10 nJy at 5 GHz, the SKA can detect 1500 Be stars and 50 OB stars per square degree, out to several kpc. It can also detect flares from 4500 M dwarfs per square degree. At 100 nJy, the numbers become about 8 times smaller. SKA surveys of the Galactic plane should be designed for high sensitivity. Deep imaging should consider the significant number of faint flares in the field, even outside the plane of the Milky Way.

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