scholarly journals The environment of FRB 121102 and possible relation to SGR/PSR J1745−2900

2020 ◽  
Vol 501 (1) ◽  
pp. L76-L79
Author(s):  
J I Katz
Keyword(s):  
Electron Density ◽  
Formation Process ◽  
Spherical Symmetry ◽  
Supernova Remnant ◽  
Line Of Sight ◽  
Plasma Cloud ◽  
Radio Bursts ◽  
Moving Plasma ◽  
Dispersion Measures ◽  
Copernican Principle

ABSTRACT Variations of the dispersion measures (DM) and rotation measures (RM) of fast radio bursts (FRBs) 121102 indicate magnetic fields ∼3–17 mG in the dispersing plasma. The electron density may be ${\sim}10^4\,$ cm−3. The observed time scales ∼1 yr constrain the size of the plasma cloud. Increasing DM excludes simple models involving an expanding supernova remnant, and the non-zero RM excludes spherical symmetry. The varying DM and RM may be attributable to the motion of plasma into or out of the line of sight to or changing electron density within slower moving plasma. The extraordinarily large RM of FRB 121102 implies an environment, and possibly also a formation process and source, qualitatively different from those of other FRB. The comparable and comparably varying RM of SGR/PSR J1745−2900 suggests it as a FRB candidate. Appendix A discusses the age of FRB 121102 in the context of a ‘Copernican Principle’.

scholarly journals Coronal electron density distributions estimated from CMEs, DH type II radio bursts, and polarized brightness measurements

2016 ◽  
Vol 121 (4) ◽  
pp. 2853-2865 ◽  
Author(s):  
Jae‐Ok Lee ◽  
Y.‐J. Moon ◽  
Jin‐Yi Lee ◽  
Kyoung‐Sun Lee ◽  
R.‐S. Kim
Keyword(s):  
Electron Density ◽  
Radio Bursts ◽  
Type Ii ◽  
Density Distributions ◽  
Type Ii Radio Bursts ◽  
Coronal Electron

scholarly journals AGILE Observations of Two Repeating Fast Radio Bursts with Low Intrinsic Dispersion Measures

2020 ◽  
Vol 890 (2) ◽  
pp. L32 ◽  
Author(s):  
C. Casentini ◽  
F. Verrecchia ◽  
M. Tavani ◽  
A. Ursi ◽  
L. A. Antonelli ◽  
...  
Keyword(s):  
Radio Bursts ◽  
Dispersion Measures

scholarly journals Some Observations of Shell-type Galactic Radio Sources

1967 ◽  
Vol 20 (3) ◽  
pp. 297 ◽  
Author(s):  
ER Hill
Keyword(s):  
Radio Emission ◽  
Spherical Symmetry ◽  
Supernova Remnants ◽  
Supernova Remnant ◽  
Milky Way ◽  
Radio Sources ◽  
Radio Observations ◽  
Shell Type ◽  
Rosette Nebula ◽  
Galactic Radio

Radio evidence for two new supernova remnants in the Southern Milky Way is presented. Some new observations of the known supernova remnant, source 1439-62, and of the Rosette nebula, a shell source but not a supernova remnant, are also presented. The problem of finding model shells to fit the radio observations is considered and it is shown that the radio emission from 1439-62 is unlikely to originate in a shell with spherical symmetry.

scholarly journals Statistical Measurements of Dispersion Measure Fluctuations of FRBs

2021 ◽  
Vol 922 (2) ◽  
pp. L31
Author(s):  
Siyao Xu ◽  
David H. Weinberg ◽  
Bing Zhang
Keyword(s):  
Electron Density ◽  
Large Scale ◽  
Density Fluctuations ◽  
Clear Correlation ◽  
Dispersion Measure ◽  
Large Dispersion ◽  
Dispersion Measures ◽  
The Difference ◽  
Electron Density Fluctuations ◽  
Scale Turbulence

Abstract Extragalactic fast radio bursts (FRBs) have large dispersion measures (DMs) and are unique probes of intergalactic electron density fluctuations. By using the recently released First CHIME/FRB Catalog, we reexamined the structure function (SF) of DM fluctuations. It shows a large DM fluctuation similar to that previously reported in Xu & Zhang, but no clear correlation hinting toward large-scale turbulence is reproduced with this larger sample. To suppress the distortion effect from FRB distances and their host DMs, we focus on a subset of CHIME catalog with DM < 500 pc cm−3. A trend of nonconstant SF and nonzero correlation function (CF) at angular separations θ less than 10° is seen, but with large statistical uncertainties. The difference found between SF and that derived from CF at θ ≲ 10° can be ascribed to the large statistical uncertainties or the density inhomogeneities on scales on the order of 100 Mpc. The possible correlation of electron density fluctuations and inhomogeneities of density distribution should be tested when several thousands of FRBs are available.

scholarly journals The Galactic Distribution of Electron Density Microstructure Inferred from Radio Scattering Observations

2001 ◽  
Vol 182 ◽  
pp. 11-16
Author(s):  
James Cordes
Keyword(s):  
Interstellar Medium ◽  
Radio Wave ◽  
Electron Density ◽  
Wave Scattering ◽  
Galactic Model ◽  
Dispersion Measures ◽  
Pulse Broadening ◽  
Galactic Distribution

AbstractI first review the observables and optics of interstellar seeing associated with radio wave scattering in the interstellar medium. I then describe the Galactic distribution of electron density and its fluctuations, as inferred from a number of observables, including angular and pulse broadening, diffractive scintillations, and dispersion measures. Propects for improving the Galactic model are outlined.

scholarly journals High-velocity interstellar absorption associated with the supernova remnant W28

2020 ◽  
Vol 495 (3) ◽  
pp. 2909-2920 ◽  
Author(s):  
Adam M Ritchey
Keyword(s):  
High Velocity ◽  
Molecular Cloud ◽  
Supernova Remnant ◽  
Line Emission ◽  
Line Of Sight ◽  
Interstellar Gas ◽  
Lower Velocity ◽  
North East ◽  
The North ◽  
Visible Wavelengths

ABSTRACT We present an analysis of moderately high-resolution optical spectra obtained for the sightline to CD−23 13777, an O9 supergiant that probes high-velocity interstellar gas associated with the supernova remnant W28. Absorption components at both high positive and high negative velocity are seen in the interstellar Na i D and Ca ii H and K lines towards CD−23 13777. The high-velocity components exhibit low Na i/Ca ii ratios, suggesting efficient grain destruction by shock sputtering. High column densities of CH+, and high CH+/CH ratios, for the components seen at lower velocity may be indicative of enhanced turbulence in the clouds interacting with W28. The highest positive and negative velocities of the components seen in Na i and Ca ii absorption towards CD−23 13777 imply that the velocity of the blast wave associated with W28 is at least 150 km s−1, a value that is significantly higher than most previous estimates. The line of sight to CD−23 13777 passes very close to a well-known site of interaction between the supernova remnant and a molecular cloud to the north-east. The north-east molecular cloud exhibits broad molecular line emission, OH maser emission from numerous locations, and bright extended GeV and TeV γ-ray emission. The sightline to CD−23 13777 is thus a unique and valuable probe of the interaction between W28 and dense molecular gas in its environs. Future observations at ultraviolet and visible wavelengths will help to better constrain the abundances, kinematics, and physical conditions in the shocked and quiescent gas along this line of sight.

scholarly journals Galactic structure and turbulence, pulsar distances, and the intergalactic medium

2012 ◽  
Vol 8 (S291) ◽  
pp. 211-216 ◽  
Author(s):  
J. M. Cordes
Keyword(s):  
Electron Density ◽  
Intergalactic Medium ◽  
Galactic Structure ◽  
Density Model ◽  
Radio Bursts ◽  
Radio Waves ◽  
Next Generation ◽  
Scattering Measurements ◽  
Galactic Model ◽  
Multi Wavelength

AbstractThis paper summarizes how multi-wavelength measurements will be aggregated to determine Galactic structure in the interstellar medium (ISM) and produce the next-generation electron density model. Fluctuations in density and magnetic field from parsec scales down to about 1000 km cause a number of propagation effects in both radio waves and cosmic rays. Density microstructure appears to include Kolmogorov-like turbulence. The next generation electron-density model, NE2012, will include about double the number of lines of sight with dispersion and scattering measurements and it will be anchored with a much larger number of pulsar parallax distances. The foreground Galactic model is crucial for inferring similar ionized structures in the intergalactic medium (IGM) from scattering measurements on high-z objects. Intergalactic scattering is discussed with reference to distant sources of radio bursts. In particular, the cosmological radio scattering horizon is defined along with its analog for the ISM.

scholarly journals On the influence of CMEs on the global 3-D coronal electron density

2011 ◽  
Vol 29 (6) ◽  
pp. 1019-1028 ◽  
Author(s):  
M. Kramar ◽  
J. Davila ◽  
H. Xie ◽  
S. Antiochos
Keyword(s):  
Electron Density ◽  
Field Configuration ◽  
Line Of Sight ◽  
Streamer Belt ◽  
Coronal Streamer ◽  
First Case ◽  
Before And After ◽  
Coronal Density ◽  
Mass Ejection ◽  
Coronal Electron

Abstract. In order to analize the influence of a Coronal Mass Ejection (CME) on the coronal streamer belt, we made 3-D reconstructions of the electron density in the corona at heliospheric distances from 1.5 to 4 R&amp;odot; for periods before and after a CME occured. The reconstructions were performed using a tomography technique. We studied two CME cases: (i) a slow CME on 1 June 2008; (ii) two fast CMEs on 31 December 2007 and 2 January 2008. For the first case of slow CME, it was found: (i) the potential magnetic field configuration in the CME initiation region before the CME does not agree with the coronal density structure while after the CME the agreement between the field and density is much better. This could be manifistation of that that the field was non-potential before the CME and after the CME the field relaxes towards a more potential state. (ii) It was shown that the dimming caused by the slow CME is not due to rotation of the corona and a line-of-sight (LOS) effect but a streamer blow out effect took place.

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