scholarly journals A new method to probe the thermal electron content of the Galaxy through spectral analysis of background sources

2016 ◽  
Vol 460 (3) ◽  
pp. 3298-3304
Author(s):  
D. I. Jones ◽  
A. P. Igoshev ◽  
M. Haverkorn
Keyword(s):  
Spectral Analysis ◽  
New Method ◽  
Electron Content ◽  
Thermal Electron ◽  
The Galaxy

A new method for determining the total electron content in Mars’ ionosphere based on Mars Express MARSIS data

2020 ◽  
Vol 182 ◽  
pp. 104812
Author(s):  
Philip Conroy ◽  
Gary Quinsac ◽  
Nicolas Floury ◽  
Olivier Witasse ◽  
Marco Cartacci ◽  
...  
Keyword(s):  
Total Electron Content ◽  
New Method ◽  
Electron Content ◽  
Total Electron ◽  
Mars Express

scholarly journals Spectral analysis of flow velocity in the contralateral artery during coronary angioplasty: A new method for assessing collateral flow

1993 ◽  
Vol 21 (7) ◽  
pp. 1574-1582 ◽  
Author(s):  
Jan J. Piek ◽  
Jacques J. Koolen ◽  
Alexander C.Metting van Rijn ◽  
Hans Bot ◽  
Gerard Hoedemaker ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Flow Velocity ◽  
Coronary Angioplasty ◽  
New Method ◽  
Collateral Flow

scholarly journals Understanding the radio relic emission in the galaxy cluster MACS J0717.5+3745: Spectral analysis

2020 ◽  
Author(s):  
K. Rajpurohit ◽  
D. Wittor ◽  
R. J. van Weeren ◽  
F. Vazza ◽  
M. Hoeft ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Galaxy Cluster ◽  
The Galaxy

scholarly journals Subhalo destruction in the Apostle and Auriga simulations

2019 ◽  
Vol 492 (4) ◽  
pp. 5780-5793 ◽  
Author(s):  
Jack Richings ◽  
Carlos Frenk ◽  
Adrian Jenkins ◽  
Andrew Robertson ◽  
Azadeh Fattahi ◽  
...  
Keyword(s):  
Dark Matter ◽  
Velocity Distribution ◽  
Galaxy Formation ◽  
Milky Way ◽  
State Of The Art ◽  
Systematic Errors ◽  
Mass Function ◽  
New Method ◽  
The Galaxy

ABSTRACT N-body simulations make unambiguous predictions for the abundance of substructures within dark matter haloes. However, the inclusion of baryons in the simulations changes the picture because processes associated with the presence of a large galaxy in the halo can destroy subhaloes and substantially alter the mass function and velocity distribution of subhaloes. We compare the effect of galaxy formation on subhalo populations in two state-of-the-art sets of hydrodynamical Λcold dark matter (ΛCDM) simulations of Milky Way mass haloes, Apostle and Auriga. We introduce a new method for tracking the orbits of subhaloes between simulation snapshots that gives accurate results down to a few kiloparsecs from the centre of the halo. Relative to a dark matter-only simulation, the abundance of subhaloes in Apostle is reduced by 50 per cent near the centre and by 10 per cent within r200. In Auriga, the corresponding numbers are 80 per cent and 40 per cent. The velocity distributions of subhaloes are also affected by the presence of the galaxy, much more so in Auriga than in Apostle. The differences on subhalo properties in the two simulations can be traced back to the mass of the central galaxies, which in Auriga are typically twice as massive as those in Apostle. We show that some of the results from previous studies are inaccurate due to systematic errors in the modelling of subhalo orbits near the centre of haloes.

Seismic ionospheric disturbances related to Chile-Illapel 2015 earthquake and tsunami observed by Swarm and ground GNSS stations

2021 ◽  
Author(s):  
Wojciech Jarmolowski ◽  
Pawel Wielgosz ◽  
Anna Krypiak-Gregorczyk ◽  
Beata Milanowska ◽  
Roger Haagmans
Keyword(s):  
Spectral Analysis ◽  
Seismic Activity ◽  
Spectral Characteristics ◽  
Precise Orbit Determination ◽  
Spatial Relations ◽  
Electron Content ◽  
Ionospheric Disturbances ◽  
Total Electron ◽  
Gnss Data ◽  
Along Track

<p>The study investigates Swarm data including in-situ electron density (ED) measured by Langmuir Probes (LP) and total electron content (TEC) from precise orbit determination (POD) GNSS receivers in time of Chile-Illapel earthquake (EQ) and tsunami in 2015. The research is based on the symbiosis of Swarm data, ground GNSS data and seismic records combined with the information on EQs and tsunamis. The FFT-based filtering and short-term Fourier transform (STFT) analysis are used in detection of seismic ionospheric disturbances (SID) in ED from LP and POD TEC data. The classification of the spectral characteristics of disturbing along-track signals is supported by their simultaneous search in ground GNSS observations, which gives an opportunity for the validation of the spectral recognition. Ground GNSS data, due to several tens of satellites and thousands of stations, provide the only full spatiotemporal view on SIDs and enable the inspection of their spatial shapes, spatial relations and speeds. The location of dense ground GNSS networks is however limited to selected places. Swarm and other LEO satellite data, in turn, are globally distributed, but they are dense only along the orbital tracks. Therefore, 1D nature of Swarm along-track observations, fast satellite movement and limited chance for spatiotemporal correlation due to the non-repeating orbits, strongly require spectral analysis for better recognition of the signals. The detection of SIDs from along-track Swarm data is also complicated due to the variety of disturbing signals occurring in the ionosphere, and the spectral analysis is also crucial there. STFT spectral approach to along-track Swarm data gives an opportunity for distinguishing the signals of different origin. The analyses of Swarm data provide interesting observations of ionospheric disturbances not only directly related with the largest EQ events and tsunami, but also occurring during entire periods of enhanced seismic activity and at larger distances from EQ epicenter. The disturbing signals triggered by the largest EQs and tsunami were also observed. However their amplitude in the ionosphere is not always such dominating as the amplitude of some other, associated disturbances on the neighboring days. This difference in scale can suggest that the electron disturbances in the ionosphere are rather more generally related to the crustal motion and seismic activity, than solely correlated with large EQs.</p>

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