Determination of plasma parameters from soft X-ray images for coronal holes /open magnetic field configurations/ and coronal large-scale structures /extended closed-field configurations/

1977 ◽  
Vol 215 ◽  
pp. 919 ◽  
Author(s):  
C. W. Maxson ◽  
G. S. Vaiana
Keyword(s):  
Magnetic Field ◽  
Large Scale ◽  
Coronal Holes ◽  
Closed Field ◽  
Plasma Parameters ◽  
X Ray ◽  
Large Scale Structures ◽  
Scale Structures ◽  
Open Magnetic Field

scholarly journals Detecting shocked intergalactic gas with X-ray and radio observations

2019 ◽  
Vol 627 ◽  
pp. A5 ◽  
Author(s):  
F. Vazza ◽  
S. Ettori ◽  
M. Roncarelli ◽  
M. Angelinelli ◽  
M. Brüggen ◽  
...  
Keyword(s):  
Large Scale ◽  
Intergalactic Medium ◽  
Thermal Emission ◽  
Intergalactic Gas ◽  
Radio Observations ◽  
X Ray ◽  
Large Scale Structures ◽  
Hot Gas ◽  
Scale Structures ◽  
Radio Band

Detecting the thermal and non-thermal emission from the shocked cosmic gas surrounding large-scale structures represents a challenge for observations, as well as a unique window into the physics of the warm-hot intergalactic medium. In this work, we present synthetic radio and X-ray surveys of large cosmological simulations in order to assess the chances of jointly detecting the cosmic web in both frequency ranges. We then propose best observing strategies tailored for existing (LOFAR, MWA, and XMM) or future instruments (SKA-LOW and SKA-MID, Athena, and eROSITA). We find that the most promising targets are the extreme peripheries of galaxy clusters in an early merging stage, where the merger causes the fast compression of warm-hot gas onto the virial region. By taking advantage of a detection in the radio band, future deep X-ray observations will probe this gas in emission, and help us to study plasma conditions in the dynamic warm-hot intergalactic medium with unprecedented detail.

scholarly journals Redshifts and Large Scale Structures

1983 ◽  
Vol 104 ◽  
pp. 159-165
Author(s):  
G. Chincarini
Keyword(s):  
Deceleration Parameter ◽  
Large Scale ◽  
Hubble Constant ◽  
Large Scale Structures ◽  
Classical Paper ◽  
Scale Structures

The effort to measure the geometry of space by experiment, that is, the determination of the Hubble Constant, Ho, and of the deceleration parameter, qo, led toward the end of the first half of the century, to the classical paper by Humason, Mayall, and Sandage (1956). Their catalogue contains 920 redshifts collected over a twenty-year period (1935–1955). Further redshifts of galaxies were measured to refine such determinations and to study the dynamics of clusters (Zwicky 1933).

scholarly journals Variations of the Coronal Radiation in X-ray Related to Coronal Holes, Active Region Loop Systems, Bright Points

1994 ◽  
Vol 143 ◽  
pp. 159-171
Author(s):  
Ester Antonucci
Keyword(s):  
Magnetic Field ◽  
Spatial Distribution ◽  
Large Scale ◽  
Coronal Holes ◽  
Active Regions ◽  
Coronal Magnetic Field ◽  
Small Scale ◽  
X Ray ◽  
Coronal Structures

The coronal features observed in X-ray emission, varying from the small-scale, short-lived bright points to the large-scale, long-lived coronal holes, are closely associated with the coronal magnetic field and its topology, and their variability depends strongly on the solar cycle. Here we discuss the spatial distribution of the coronal structures, the frequency distribution of the brightness variations in active regions, and the role of magnetic reconnection in determining the variability of the coronal features, on the basis of the new observations of the soft X-ray emission recently obtained with the Yohkoh satellite and the NIXT experiment.

scholarly journals Solar Mass Ejections and Coronal Holes

1996 ◽  
Vol 154 ◽  
pp. 105-112
Author(s):  
Arvind Bhatnagar
Keyword(s):  
Coronal Hole ◽  
Large Scale ◽  
Neutral Line ◽  
Coronal Holes ◽  
Field Configuration ◽  
Solar Mass ◽  
X Ray ◽  
Filament Eruption ◽  
Open Magnetic Field ◽  
Interplanetary Scintillations

AbstractIn this paper we present observations of two types of solar mass ejections, which seem to be associated with the location of coronal holes. In the first type, a filament eruption was observed near a coronal hole, which gave rise to a strong interplanetary scintillations, as detected by IPS observations. In the second type, several large scale soft X-ray ‘blow-outs’ were observed in the YOHKOH SXT X-ray movies, in all the cases they erupted from or near the boundary of coronal holes and over the magnetic neutral line. It is proposed that the open magnetic field configuration of the coronal hole provides, the necessary field structure for reconnection to take place, which in turn is responsible for filament eruption, from relatively lower heights. While, in the case of X-ray ‘blow-outs’, the reconnection takes place at a greater height, resulting in high temperature soft X-ray emission visible as X-ray ‘blow-outs’.

Examining the optical intensity and magnetic field expansion factor in the open magnetic field regions associated with coronal holes

2019 ◽  
Vol 15 (S354) ◽  
pp. 228-231
Author(s):  
Chia-Hsien Lin ◽  
Guan-Han Huang ◽  
Lou-Chuang Lee
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Coronal Holes ◽  
Closed Field ◽  
Logarithmic Scale ◽  
Expansion Factor ◽  
Astrophysical Journal ◽  
Field Lines ◽  
The Relationship ◽  
Open Magnetic Field

AbstractCoronal holes can be identified as the darkest regions in EUV or soft X-ray images with predominantly unipolar magnetic fields (LIRs) or as the regions with open magnetic fields (OMF). Our study reveals that only 12% of OMF regions are coincident with LIRs. The aim of this study is to investigate the conditions that affect the EUV intensity of OMF regions. Our results indicate that the EUV intensity and the magnetic field expansion factor of the OMF regions are weakly positively correlated when plotted in logarithmic scale, and that the bright OMF regions are likely to locate inside or next to the regions with closed field lines. We empirically determined a linear relationship between the expansion factor and the EUV intensity. The relationship is demonstrated to improve the consistency from 12% to 23%. The results have been published in Astrophysical Journal (Huang et al. 2019).

scholarly journals FM6: Summary of Session #5 on Accretion and Feedback in Active Galactic Nuclei

2015 ◽  
Vol 11 (A29B) ◽  
pp. 101-112
Author(s):  
Laura Brenneman
Keyword(s):  
Active Galactic Nuclei ◽  
Large Scale ◽  
Galaxy Cluster ◽  
Galactic Nuclei ◽  
Starburst Galaxies ◽  
X Ray ◽  
Large Scale Structures ◽  
Scale Structures

AbstractFocus Meeting 6 of the IAU 2015 Symposium centered around the topic of “X-ray Surveys of the Hot and Energetic Universe.” Within this two-day meeting seven sessions (31 total talks) were presented, whose topics included galaxy cluster physics and evolution, cluster cosmological studies, AGN demographics and X-ray binary populations, first quasars, accretion and feedback, large-scale structures, and normal and starburst galaxies. Herein, I summarize the results presented during session #5, which focused on AGN accretion and feedback. Six authors contributed their work to our session: Laura Brenneman, Kazushi Iwasawa, Massimo Gaspari, Michaela Hirschmann, Franz Bauer and Yuan Liu. I provide a brief introduction below, followed by the details of the presentations of each author in the order in which the presentations were given.

scholarly journals THE EVOLUTION AND ENVIRONMENTS OF X-RAY EMITTING ACTIVE GALACTIC NUCLEI IN HIGH-REDSHIFT LARGE-SCALE STRUCTURES

2012 ◽  
Vol 746 (2) ◽  
pp. 155 ◽  
Author(s):  
N. Rumbaugh ◽  
D. D. Kocevski ◽  
R. R. Gal ◽  
B. C. Lemaux ◽  
L. M. Lubin ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Large Scale ◽  
High Redshift ◽  
Galactic Nuclei ◽  
X Ray ◽  
Large Scale Structures ◽  
Scale Structures

Examination of the EUV Intensity in the Open Magnetic Field Regions Associated with Coronal Holes

2020 ◽  
Author(s):  
Guan-Han Huang ◽  
Chia-Hsien Lin ◽  
Lou Chuang Lee
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Order Approximation ◽  
Coronal Holes ◽  
Closed Field ◽  
Spatial And Temporal Distributions ◽  
Field Lines ◽  
First Order Approximation ◽  
Log Normal ◽  
Open Magnetic Field

<p>Coronal holes can be identified as the regions with magnetic field lines extending far away from the Sun, or the darkest regions in EUV/X-ray images with predominantly unipolar magnetic fields. A comparison between the locations of our determined regions with open magnetic field lines (OMF) and regions with low EUV intensity (LIR) reveals that only 12% of the OMF regions coincide with the LIRs. The aim of this study is to investigate the conditions leading to the different brightnesses of OMF regions, and to provide a means to predict whether an OMF region would be bright or dark. Examining the statistical distribution profiles of the magnetic field expansion factor (f<sub>s</sub>) and Atmospheric Imaging Assembly 193 Å intensity (I<sub>193</sub>) reveals that both profiles are approximately log-normal. The analysis of the spatial and temporal distributions of f<sub>s</sub> and I<sub>193</sub> indicates that the bright OMF regions often are inside or next to regions with closed field lines, including quiet-Sun regions and regions with strong magnetic fields. Examining the relationship between I<sub>193</sub> and f<sub>s</sub> reveals a weak positive correlation between log I<sub>193</sub> and log f<sub>s</sub> , with a correlation coefficient ≈ 0.39. As a first-order approximation, the positive relationship is determined to be log I<sub>193</sub> = 0.62 log f<sub>s</sub> + 1.51 based on the principle of the whitening/dewhitening transformation. This linear relationship is demonstrated to increase the consistency between the OMF regions and LIRs from 12% to 23%.</p>

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