scholarly journals Radio and X-ray connection in radio mini-halos: Implications for hadronic models

2020 ◽  
Vol 640 ◽  
pp. A37 ◽  
Author(s):  
A. Ignesti ◽  
G. Brunetti ◽  
M. Gitti ◽  
S. Giacintucci
Keyword(s):  
Magnetic Field ◽  
Large Fraction ◽  
Cosmic Ray ◽  
Physical Parameters ◽  
Model Parameters ◽  
Relativistic Electrons ◽  
X Rays ◽  
X Ray ◽  
Hadronic Model ◽  
Radio Halos

Context. A large fraction of cool-core clusters are known to host diffuse, steep-spectrum radio sources, called radio mini-halos, in their cores. Mini-halos reveal the presence of relativistic particles on scales of hundreds of kiloparsecs, beyond the scales directly influenced by the central active galactic nucleus (AGN), but the nature of the mechanism that produces such a population of radio-emitting, relativistic electrons is still debated. It is also unclear to what extent the AGN plays a role in the formation of mini-halos by providing the seeds of the relativistic population. Aims. In this work we explore the connection between thermal and non-thermal components of the intra-cluster medium in a sample of radio mini-halos and we study the implications within the framework of a hadronic model for the origin of the emitting electrons. Methods. For the first time, we studied the thermal and non-thermal connection by carrying out a point-to-point comparison of the radio and the X-ray surface brightness in a sample of radio mini-halos. We extended the method generally applied to giant radio halos by considering the effects of a grid randomly generated through a Monte Carlo chain. Then we used the radio and X-ray correlation to constrain the physical parameters of a hadronic model and we compared the model predictions with current observations. Results. Contrary to what is generally reported in the literature for giant radio halos, we find that the mini-halos in our sample have super-linear scaling between radio and X-rays, which suggests a peaked distribution of relativistic electrons and magnetic field. We explore the consequences of our findings on models of mini-halos. We use the four mini-halos in the sample that have a roundish brightness distribution to constrain model parameters in the case of a hadronic origin of the mini-halos. Specifically, we focus on a model where cosmic rays are injected by the central AGN and they generate secondaries in the intra-cluster medium, and we assume that the role of turbulent re-acceleration is negligible. This simple model allows us to constrain the AGN cosmic ray luminosity in the range ∼1044−46 erg s−1 and the central magnetic field in the range 10–40 μG. The resulting γ-ray fluxes calculated assuming these model parameters do not violate the upper limits on γ-ray diffuse emission set by the Fermi-LAT telescope. Further studies are now required to explore the consistency of these large magnetic fields with Faraday rotation studies and to study the interplay between the secondary electrons and the intra-cluster medium turbulence.

Inverse Compton X-Rays from Giant Radio Galaxies

1996 ◽  
Vol 175 ◽  
pp. 256-258
Author(s):  
D. Tsakiris ◽  
J.P. Leahy ◽  
R.G. Strom ◽  
C.R. Barber
Keyword(s):  
Magnetic Field ◽  
Minimum Energy ◽  
Radio Galaxies ◽  
Relativistic Electrons ◽  
X Rays ◽  
X Ray ◽  
Inverse Compton Scattering ◽  
Inverse Compton ◽  
Image Position ◽  
Low Magnetic Field

The X-ray radiation from inverse Compton scattering of CMB photons by the relativistic electrons in ‘radio’ lobes provides a direct measure of their column density at a known energy, unlike synchrotron radiation which also depends on the unknown magnetic field. Thus by combining inverse Compton and radio data we can separately determine the particle energies and field strengths, rather than having to rely on uncertain estimates like minimum energy. The predicted flux is and strong IC signal requires high radio flux and low magnetic field, properties of giant radio galaxies. On the other hand the minimum detectable count rate, Imin, increases with the target size due to the larger background contribution. As a result the detectability of IC X-rays for ROSAT PSPC B measurements is roughly, assuming a spectral index of 0.75. After making detailed prediction of SIC for a number of objects of the 3CR sample, the best candidates were 3C 236, 3C 326, and 4C 73.08.

scholarly journals Multiwavelength Modeling the SED of Strongly Interacting Binaries

2011 ◽  
Vol 7 (S282) ◽  
pp. 65-66
Author(s):  
Augustin Skopal
Keyword(s):  
Physical Parameters ◽  
X Rays ◽  
Physical Processes ◽  
Short Contribution ◽  
Composite Spectrum ◽  
X Ray ◽  
Strongly Interacting ◽  
Low Mass ◽  
X Ray Binaries

AbstractThe spectrum of strongly interacting binaries, as for example, high and low mass X-ray binaries, symbiotic (X-ray) binaries and/or classical and recurrent novae, consists of more components of radiation contributing from hard X-rays to radio wavelengths. To understand the basic physical processes responsible for the observed spectrum we have to disentangle the composite spectrum into its individual components, i.e. to determine their physical parameters. In this short contribution I demonstrate the method of modeling the multiwavelength SED on the example of the extragalactic super-soft X-ray source RX J0059.1-7505 (LIN 358).

scholarly journals The X-ray/UV ratio in active galactic nuclei: dispersion and variability

2018 ◽  
Vol 619 ◽  
pp. A95 ◽  
Author(s):  
E. Chiaraluce ◽  
F. Vagnetti ◽  
F. Tombesi ◽  
M. Paolillo
Keyword(s):  
Black Hole ◽  
Cosmological Parameters ◽  
Multivariate Regression Analysis ◽  
Physical Parameters ◽  
Distance Modulus ◽  
X Rays ◽  
Viewing Angle ◽  
Black Hole Mass ◽  
Intrinsic Variability ◽  
X Ray

Context. The well established negative correlation between the αOX spectral slope and the optical/ultraviolet (UV) luminosity, a by-product of the relation between X-rays and optical/UV luminosity, is affected by relatively large dispersion. The main contributors to this dispersion can be variability in the X-ray/UV ratio and/or changes in fundamental physical parameters. Aims. We want to quantify the contribution from variability within single sources (intra-source dispersion) and that from variations of other quantities different from source to source (inter-source dispersion). Methods. We use archival data from the XMM-Newton Serendipitous Source Catalog (XMMSSC) and from the XMM-OM Serendipitous Ultraviolet Source Survey (XMMOM-SUSS3). We select a sub-sample in order to decrease the dispersion of the relation due to the presence of radio-loud and broad absorption line objects, and that due to absorptions in both X-ray and optical/UV bands. We use the structure function (SF) to estimate the contribution from variability to the dispersion. We analyse the dependence of the residuals of the relation on various physical parameters in order to characterise the inter-source dispersion. Results. We find a total dispersion of σ ∼ 0.12 and find that intrinsic variability contributes 56% of the variance of the αOX − LUV relation. If we select only sources with a larger number of observational epochs (≥3) the dispersion of the relation decreases by approximately 15%. We find weak but significant dependencies of the residuals of the relation on black-hole mass and on Eddington ratio, which are also confirmed by a multivariate regression analysis of αOX as a function of UV luminosity and black-hole mass and/or Eddington ratio. We find a weak positive correlation of both the αOX index and the residuals of the αOX − LUV relation with inclination indicators, such as the full width at half maximum (Hβ) and the equivalent width (EW)[OIII], suggesting a weak increase of X-ray/UV ratio with the viewing angle. This suggests the development of new viewing angle indicators possibly applicable at higher redshifts. Moreover, our results suggest the possibility of selecting a sample of objects, based on their viewing angle and/or black-hole mass and Eddington ratio, for which the αOX − LUV relation is as tight as possible, in light of the use of the optical/UV – X-ray luminosity relation to build a distance modulus (DM)-z plane and estimate cosmological parameters.

scholarly journals Investigating the Magnetospheres of Rapidly Rotating B-type Stars

2016 ◽  
Vol 12 (S329) ◽  
pp. 369-372
Author(s):  
C. L. Fletcher ◽  
V. Petit ◽  
Y. Nazé ◽  
G. A. Wade ◽  
R. H. Townsend ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Centrifugal Force ◽  
Point Of View ◽  
Closed Field ◽  
Theoretical Point ◽  
X Rays ◽  
Rapid Rotation ◽  
X Ray ◽  
Surface Magnetic Field

AbstractRecent spectropolarimetric surveys of bright, hot stars have found that ~10% of OB-type stars contain strong (mostly dipolar) surface magnetic fields (~kG). The prominent paradigm describing the interaction between the stellar winds and the surface magnetic field is the magnetically confined wind shock (MCWS) model. In this model, the stellar wind plasma is forced to move along the closed field loops of the magnetic field, colliding at the magnetic equator, and creating a shock. As the shocked material cools radiatively it will emit X-rays. Therefore, X-ray spectroscopy is a key tool in detecting and characterizing the hot wind material confined by the magnetic fields of these stars. Some B-type stars are found to have very short rotational periods. The effects of the rapid rotation on the X-ray production within the magnetosphere have yet to be explored in detail. The added centrifugal force due to rapid rotation is predicted to cause faster wind outflows along the field lines, leading to higher shock temperatures and harder X-rays. However, this is not observed in all rapidly rotating magnetic B-type stars. In order to address this from a theoretical point of view, we use the X-ray Analytical Dynamical Magnetosphere (XADM) model, originally developed for slow rotators, with an implementation of new rapid rotational physics. Using X-ray spectroscopy from ESA’s XMM-Newton space telescope, we observed 5 rapidly rotating B-types stars to add to the previous list of observations. Comparing the observed X-ray luminosity and hardness ratio to that predicted by the XADM allows us to determine the role the added centrifugal force plays in the magnetospheric X-ray emission of these stars.

scholarly journals 1/4 Ke V Diffuse Background and the Local Interstellar Medium

1989 ◽  
Vol 120 ◽  
pp. 536-536
Author(s):  
S.L. Snowden
Keyword(s):  
Interstellar Medium ◽  
Filling Factor ◽  
Thermal Emission ◽  
Mean Free Path ◽  
Physical Parameters ◽  
X Rays ◽  
Local Interstellar Medium ◽  
X Ray ◽  
Diffuse Background ◽  
X Ray Background

The 1/4 keV diffuse X-ray background (SXRB) is discussed in relation to the local interstellar medium (LISM). The most likely source for these soft X-rays is thermal emission from a hot diffuse plasma. The existence of a non-zero flux from all directions and the short ISM mean free path of these X-rays (1020HI cm-2), coupled with ISM pressure constraints, imply that the plasma has a local component and that it must, at least locally (nearest hundred parsecs), have a large filling factor. Our understanding of the geometry and physical parameters of the LISM is therefore directly tied to our understanding of the SXRB.

scholarly journals X-ray Dips in AGN and Microquasars – Collapse Timescales of Inner Accretion Disc

2020 ◽  
Author(s):  
Mayur B Shende ◽  
Prashali Chauhan ◽  
Prasad Subramanian
Keyword(s):  
Collisionless Plasma ◽  
Cosmic Ray ◽  
Outer Radius ◽  
Accretion Disc ◽  
Accretion Discs ◽  
X Rays ◽  
Temporal Behaviour ◽  
X Ray ◽  
Ray Diffusion ◽  
3C 120

Abstract The temporal behaviour of X-rays from some AGN and microquasars is thought to arise from the rapid collapse of the hot, inner parts of their accretion discs. The collapse can occur over the radial infall timescale of the inner accretion disc. However, estimates of this timescale are hindered by a lack of knowledge of the operative viscosity in the collisionless plasma comprising the inner disc. We use published simulation results for cosmic ray diffusion through turbulent magnetic fields to arrive at a viscosity prescription appropriate to hot accretion discs. We construct simplified disc models using this viscosity prescription and estimate disc collapse timescales for 3C 120, 3C 111, and GRS 1915+105. The Shakura-Sunyaev α parameter resulting from our model ranges from 0.02 to 0.08. Our inner disc collapse timescale estimates agree well with those of the observed X-ray dips. We find that the collapse timescale is most sensitive to the outer radius of the hot accretion disc.

scholarly journals DSC reveals variation in enthalpy associated with free water molecules in water-ethanol solution exposed to x-rays and magnetic field

2021 ◽  
Vol 17 (1) ◽  
pp. 07-07
Author(s):  
Nirmal Chandra Sukul ◽  
Tandra Sarkar ◽  
Atheni Konar ◽  
Md. Amir Sohel ◽  
Asmita Sengupta ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Aqueous Ethanol ◽  
Free Water ◽  
Ethanol Solution ◽  
Water Molecules ◽  
X Rays ◽  
Standard Medium ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Homeopathic Drugs

Aqueous ethanol is the standard medium for all drugs used in homeopathy. X-ray and Magnetispoli ambo are 2 homeopathic drugs prepared by exposure of aqueous ethanol to x-rays and static magnetic field, respectively.Mother tinctures (MT)weresuccessively diluted with solvent 1:100 and succussed in several steps to prepare centesimal potencies 8 cH, 14 cH and 32 cH. The solvent was processed in the same way. Although identical in chemical composition (0.03 molar ethanol) and water content (96%) these preparations like the Mother tinctures and three potencies of X-ray and Magnetispoli amboexhibit different therapeutic pathological effects. Potency 8cH of each preparation was diluted with water to reach concentrations 4%, 20%, 40% and 80% ethanol. The aim of the study was to establish whether these potencies exhibited variation in free water molecules. Differential Scanning Calorimetry (DSC) of MT and potencies exhibited almost similar freezing and melting points, but they remarkably differed in freezing and melting enthalpy and free water molecules. The various dilutions of potency 8cH exhibited variation in enthalpies and free water molecules, being this variation independent of the amount of water added. We conclude that exposure of aqueous ethanol to x-rays and magnetic field, with subsequent dilution and agitation induces changes in the solvent involving free water molecules. All X-ray and Magnetispoli ambo potencies were analyzed by means of Raman spectroscopy for free water molecules. The results were compared to the ones of DSC, being more or less similar.

scholarly journals X-Ray Evidence for the Acceleration, Containment, and Emission of High Energy Flare Particles

1974 ◽  
Vol 57 ◽  
pp. 421-422 ◽  
Author(s):  
Kenneth J. Frost
Keyword(s):  
Cosmic Ray ◽  
High Energy ◽  
Solar Observatory ◽  
Time Structure ◽  
Radio Bursts ◽  
X Rays ◽  
Thermal Component ◽  
X Ray ◽  
Type Iii ◽  
Explosive Phase

An instrument aboard the Fifth Orbiting Solar Observatory has observed hard solar X-rays from January 1969 to May 1972. A large number of X-ray bursts generated by solar cosmic ray flares have been observed. The X-ray bursts consist, in general, of two non-thermal components. The earliest occurring non-thermal component, coincident with the explosive phase, consists of a group of one to about ten X-ray bursts that are, for each burst, approximately 10 s duration and symmetrical in rise and decay. The time structure and multiplicity of these bursts is remarkably similar to that found in type III radio bursts in the meterwave band. The spectra of these bursts steepens sharply at energies greater than 100 keV indicating a limit at this energy for electron acceleration during the explosive or flash phase of the flare. For several flares these multiple X-ray bursts have occurred in coincidence with a group of type III bursts.

scholarly journals Pair Production in AGN

1989 ◽  
Vol 134 ◽  
pp. 194-196
Author(s):  
C. Done ◽  
A. C. Fabian
Keyword(s):  
Pair Production ◽  
Compton Scattering ◽  
Energy Flux ◽  
Large Fraction ◽  
Small Region ◽  
X Rays ◽  
X Ray ◽  
Electron Positron ◽  
Γ Rays ◽  
Radiant Power

The X-ray luminosity and variability of many AGN are sufficiently extreme that any hard γ-rays produced in the source will collide with the X-rays and create electron-positron pairs, rather than escape. A small region where vast amounts of energy are produced, such as an AGN, is an ideal place to accelerate particles to relativistic energies and so produce γ-rays by Compton scattering. The observed X-ray spectra of AGN are hard and indicate that most of the luminosity is at the highest energies so that absorption of the γ-rays represents a large fraction of the energy flux, which can then be re-radiated at lower energies. Pairs can thus effectively reprocess much of the radiant power in an AGN.

scholarly journals Thermal and non-thermal connection in radio mini-halos

2018 ◽  
Vol 14 (S342) ◽  
pp. 137-140
Author(s):  
A. Ignesti ◽  
G. Brunetti ◽  
M. Gitti ◽  
S. Giacintucci
Keyword(s):  
Magnetic Field ◽  
Surface Brightness ◽  
X Rays ◽  
X Ray ◽  
Point Analysis ◽  
Spectrum Radio ◽  
Point To Point ◽  
The Magnetic Field ◽  
Relativistic Particles ◽  
Open Issues

AbstractSeveral cool-core clusters are known to host a radio mini-halo, a diffuse, steep-spectrum radio source located in their cores, thus probing the presence of non-thermal components as magnetic field and relativistic particles on scales not directly influenced by the central AGN. The nature of the mechanism that produces a population of radio-emitting relativistic particles on the scale of hundreds of kiloparsecs is still unclear. At the same time, it is still debated if the central AGN may play a role in the formation of mini-halos by providing the seed of the relativistic particles. We aim to investigate these open issues by studying the connection between thermal and non-thermal components of the intra-cluster medium. We performed a point-to-point analysis of the radio and the X-ray surface brightness of a compilation of mini-halos. We find that mini-halos have super-linear scalings between radio and X-rays, with radio brightness declining more steeply than the X-ray brightness. This trend is opposite to that generally observed in giant radio halos, thus marking a possible difference in the physics of the two radio sources. Finally, using the scalings between radio and X-rays and assuming a hadronic origin of mini-halos we derive constraints on the magnetic field in the core of the hosting clusters.

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