scholarly journals Thermal Pressures in Neutral Clouds inside the Local Bubble, as Determined from CiFine‐Structure Excitations

2002 ◽  
Vol 580 (2) ◽  
pp. 938-949 ◽  
Author(s):  
Edward B. Jenkins
Keyword(s):  
Local Bubble ◽  
Neutral Clouds

scholarly journals Measurements of the Size and Pressure of the Local Bubble Towards Eridanus

1997 ◽  
Vol 166 ◽  
pp. 279-282
Author(s):  
D.N. Burrows ◽  
Z. Guo
Keyword(s):  
Thermal Pressure ◽  
Local Bubble ◽  
X Ray ◽  
Neutral Clouds ◽  
Good Agreement

AbstractWe have measured the size and pressure of the Local Bubble in the direction of the constellation Eridanus using ROSAT PSPC observations of soft X-ray “shadows” cast by neutral clouds against the bright X-ray emission from the Orion-Eridanus superbubble. We discuss the technique and present our results for the size of the Local Bubble in the directions of our shadowing fields. Using these distances and the measured soft X-ray emission measures, we derive the Local Bubble’s thermal pressure. For four lines of sight in Eridanus, we obtain pressures of about 1.2 × 104 K cm−3, in good agreement with measurements in several other directions.

scholarly journals Can the Local Bubble explain the radio background?

2021 ◽  
Vol 502 (2) ◽  
pp. 2807-2814
Author(s):  
Martin G H Krause ◽  
Martin J Hardcastle
Keyword(s):  
Magnetic Field ◽  
Energy Density ◽  
Radio Emission ◽  
Magnetic Energy ◽  
Cosmic Ray ◽  
Observational Constraints ◽  
Local Bubble ◽  
Magnetic Energy Density ◽  
Magnetic Field Model ◽  
Radio Background

ABSTRACT The ARCADE 2 balloon bolometer along with a number of other instruments have detected what appears to be a radio synchrotron background at frequencies below about 3 GHz. Neither extragalactic radio sources nor diffuse Galactic emission can currently account for this finding. We use the locally measured cosmic ray electron population, demodulated for effects of the Solar wind, and other observational constraints combined with a turbulent magnetic field model to predict the radio synchrotron emission for the Local Bubble. We find that the spectral index of the modelled radio emission is roughly consistent with the radio background. Our model can approximately reproduce the observed antenna temperatures for a mean magnetic field strength B between 3 and 5 nT. We argue that this would not violate observational constraints from pulsar measurements. However, the curvature in the predicted spectrum would mean that other, so far unknown sources would have to contribute below 100 MHz. Also, the magnetic energy density would then dominate over thermal and cosmic ray electron energy density, likely causing an inverse magnetic cascade with large variations of the radio emission in different sky directions as well as high polarization. We argue that this disagrees with several observations and thus that the magnetic field is probably much lower, quite possibly limited by equipartition with the energy density in relativistic or thermal particles (B = 0.2−0.6 nT). In the latter case, we predict a contribution of the Local Bubble to the unexplained radio background at most at the per cent level.

scholarly journals β–radioactive cosmic rays in a diffusion model: Test for a local bubble?

2002 ◽  
Vol 381 (2) ◽  
pp. 539-559 ◽  
Author(s):  
F. Donato ◽  
D. Maurin ◽  
R. Taillet
Keyword(s):  
Cosmic Rays ◽  
Diffusion Model ◽  
Model Test ◽  
Local Bubble

scholarly journals Fingerprint of Galactic Loop I on polarized microwave foregrounds

2018 ◽  
Vol 617 ◽  
pp. A90 ◽  
Author(s):  
Hao Liu
Keyword(s):  
Supernova Explosion ◽  
Large Area ◽  
Microwave Background ◽  
Local Bubble ◽  
Galactic Emission ◽  
Primordial Gravitational Waves ◽  
Polarized Emission ◽  
Supernova Explosions ◽  
Foreground Analysis ◽  
The Magnetic Field

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.

FUSE Observations of the Loop I∕Local Bubble Interaction Region

2009 ◽  
Author(s):  
S. M. Sallmen ◽  
E. J. Korpela ◽  
H. Yamashita ◽  
Randall K. Smith ◽  
Steven L. Snowden ◽  
...  
Keyword(s):  
Interaction Region ◽  
Local Bubble ◽  
Bubble Interaction

scholarly journals On the Shape of the Local Bubble

2020 ◽  
Vol 10 (01) ◽  
pp. 11-27
Author(s):  
Lorenzo Zaninetti
Keyword(s):  
Local Bubble

scholarly journals A Supernova at 50 PC: Effects on the Earth’s Atmosphere and Biota

2017 ◽  
Author(s):  
A.L Melott ◽  
B.C. Thomas ◽  
M. Kachelrieß ◽  
D.V. Semikoz ◽  
A.C. Overholt
Keyword(s):  
Magnetic Field ◽  
Transverse Field ◽  
Cosmic Ray ◽  
Magnetic Field Effects ◽  
Field Orientation ◽  
Local Bubble ◽  
Coherent Field ◽  
Computational Procedures ◽  
Cosmic Ray Flux ◽  
Disordered Magnetic

ABSTRACTRecent 60Fe results have suggested that the estimated distances of supernovae in the last few million years should be reduced from ∼100 pc to ∼50 pc. Two events or series of events are suggested, one about 2.7 million years to 1.7 million years ago, and another may at 6.5 to 8.7 million years ago. We ask what effects such supernovae are expected to have on the terrestrial atmosphere and biota. Assuming that the Local Bubble was formed before the event being considered, and that the supernova and the Earth were both inside a weak, disordered magnetic field at that time, TeV-PeV cosmic rays at Earth will increase by a factor of a few hundred. Tropospheric ionization will increase proportionately, and the overall muon radiation load on terrestrial organisms will increase by a factor of ∼150. All return to pre-burst levels within 10kyr. In the case of an ordered magnetic field, effects depend strongly on the field orientation. The upper bound in this case is with a largely coherent field aligned along the line of sight to the supernova, in which case TeV-PeV cosmic ray flux increases are ∼104; in the case of a transverse field they are below current levels. We suggest a substantial increase in the extended effects of supernovae on Earth and in the “lethal distance” estimate; more work is needed. This paper is an explicit followup to Thomas et al. (2016). We also here provide more detail on the computational procedures used in both works.

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