Pure Thermal Spectrum Research Articles

MASSIVE PARTICLE TUNNELING RATE OF KERR-NEWMAN-ANTI-DE SITTER BLACK HOLE BY HAMILTON-JACOBI METHOD

Using Parikh and Wilczek’s opinion tunneling rate of Hawking radiations of Kerr-Newman-anti-de Sitter (KNAdS) black hole has been investigated by Hamilton-Jacobi method. Involving the self-gravitation effect of the emitted particles, energy and angular momentum has been taken as conserved and considered the space time background as dynamical. The explored results shown that the massive particle tunneling rate is related to the change of Bekenstein-Hawking entropy and the derived emission spectrum deviates from the pure thermal spectrum.

Hawking radiation from a Reissner-Nordstrom-AdS black hole with integral monopoles in extended phase space

In recent years, thermodynamics and phase transitions of black holes in extended phase space have been extensively studied. The results show that the original first law of thermodynamics needs revising and new phase transitions will appear. However, so far, Hawking tunneling radiation has not been widely studied in the extended phase space. In particular, whether the tunneling radiation probability changes at this time is still uncertain. This work focuses on this topic, that is, to calculate the specific value of the tunneling probability in the extended phase space and ascertains whether the results obtained in the normal phase space are consistent with those in the extended phase space. The methods used herein are described below. Taking Reissner-Nordstrom-AdS black holes with global monopole for example, the cosmological parameters are regarded as dynamic variables, which is different from previous treatment methods that regard them as constants and ignore their contributions to the tunneling probability. In particular, cosmological parameters are introduced and regarded as thermodynamic pressure when the tunneling probability is calculated, and their contribution to the tunneling probability is considered. In the work the tunneling process of mass particles is mainly studied. The outgoing particles are viewed as spherical de Broglie waves, and then the relative phase velocity and group velocity are calculated. The geodesic equation is obtained according to the relationship between the two velocities, and the tunneling probability is calculated from the geodesic equation. It is concluded that the results show that the tunneling probability of the ingoing particles is proportional to the difference in the Bekenstein-Hawking entropy of the black hole before and after the particles tunnel, and the radiation spectrum deviates from the pure thermal spectrum, which is exactly the same as the case that the cosmological parameters are treated as constants. This means that the tunneling probability of particles can be obtained in the extended phase space, and the tunneling process does not depend on thermodynamic parameters. In addition, it is found that although the global monopole affects the dynamical behavior and thermodynamic quantity of the particle, it does not affect the entropy change or tunneling rate. In other words, the conclusion that the tunneling probability in extended phase space is exactly the same as that in normal phase space does not depend on the space-time topology.

Tunneling effect of <inline-formula><tex-math id="M2">\begin{document}$ \mathbf{S}\mathbf{L}\left(\mathit{n}, \mathit{R}\right) $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="1-20221415_M2.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="1-20221415_M2.png"/></alternatives></inline-formula> Toda black hole

The SL(<i>n</i>,<i>R</i>) Toda black hole is an ideal field for us to study black hole physics because of its excellent mathematical structure and high symmetry. This work is mainly to study the Hawking radiation of SL(<i>n</i>,<i>R</i>) Toda black hole and and the problem about its related black hole information loss . For simplicity, we only consider the Hawking radiation by calculating the tunneling effect of particles with zero rest mass near the event horizon under the four-dimensional static spherical symmetric SL(<i>n</i>,<i>R</i>) Toda black hole. In the process of particle tunneling through the event horizon of the black hole, due to the conservation of energy, the mass of black hole will be changed, which will cause the event horizon to shrink. Therefore, the reaction of tunneling particles to the background space-time leads to the dynamic change of spacetime metric, that is, the self-gravitational action of the particles generates the tunneling barrier. The tunneling probability of the particle passing through the event horizon depends on the change of the black hole entropy before and after the particle exits. Under certain conditions, our results are consistent with those of RN black holes and Schwartz black holes, and the calculation results once again support the tunneling model proposed by Parikh and Wilczek. This semi-classical image shows that the new black hole radiation spectrum is not a pure heat spectrum, but there is a small deviation from the pure thermal spectrum. From the knowledge of probability theory, it can be proved that there is a correlation process between non-thermal spectra. According to the Shannon entropy definition, the black hole entropy is analogous to Shannon information entropy. We calculate the SL(<i>n</i>,<i>R</i>) Toda black hole information paradox, and find that the correlation between the particles emitted from black hole can carry information and keep the information of black hole unchanged. The specific source of this correlation, as well as the generation mechanism, remains to be further studied. The research on the problem about black hole information loss reveals that information conservation remains true when gravitational correlations among Hawking radiations are properly taken into account. Information conservation principle thus states that the Hawking radiation is unitary, which shows that the dynamics of a black hole obeys the laws of quantum mechanics. Since a black hole is a result of general relativity, the unitarity of a black hole definitely indicates the possibility of a unified gravity and quantum mechanics.

Hawking Radiations of Kerr-Newman Black Hole in de Sitter Spacetime by Hamilton-Jacobi Method

Incorporating Parikh and Wilczek’s opinion Hawking radiations of Kerr-Newman-de Sitter (KNdS) black hole has been investigated by Hamilton-Jacobi method. We have assumed the space time background as dynamical, energy and angular momentum as conserved incorporating the self-gravitation effect of the emitted particles. We have shown that the massive particle tunneling rate is related to the change of Bekenstein-Hawking entropy and the derived emission spectrum deviates from the pure thermal spectrum.

Correlation and the black hole information loss problem

Information is physical, it cannot simply disappear in any physical process. This basic principle of information science constitutes one of the most important elements for the very foundation to our daily life and to our understanding of the universe. However, this fundamental principle is challenged by the physics of black holes. Classic black holes was viewed as only capable of absorbing but not emitting particles, so black holes look completely black. All matter that falls into the black hole will be stored in the black hole forever, and the information carry by these matter will always be stored in the black hole. Although the information in the black hole cannot be seen, we know that the information has not been lost. After considering the quantum effect, the black hole is no longer completely black. By considering quantum effect of black hole, Hawking shows that black holes emit thermal radiation like ordinary hot bodies. It is well known that there is no correlation between thermal radiation, therefore no information can be carried out by Hawking radiation. With the black hole evaporating, the information inside the black hole will gradually be lost. However, the unitary property of quantum mechanics indicates that information is conserved, therefore, the loss of black hole information conflicts with the unitary of quantum mechanics, this is the so-called mystery of black hole information loss. This problem reflects the conflict between gravitational theory and quantum theory, and attracts wide attention of scientists. Whether there is a correlation between Hawking radiation is the key to solving the problem of black hole information loss. Without considering the self-gravitating of the radiating particles in Hawkings initial calculations, he obtained the results of the pure thermal spectrum, so his result is inconsistent with energy conservation. Kraus and Wilczek show that the thermal spectrum may be corrected if the self-gravitating of the radiant particles is taken into account, thus Hawking radiations must be correlated, and their correlations can carry away information encoded within. This paper firstly introduced the black hole radiation non-thermal spectrum obtained by Parikh and Wilczek, who use the method of quantum tunneling after counting the self-gravitating of radiation particles; then it also introduced the research of Zhang et al., which proves that the entropy is conservation during black hole radiation process based on the non-thermal spectrum obtained by Parikh and Wilczek; and finally we proposed a possible physical mechanism for the correlation between black hole radiation, which shows that the gravitational correlation between the black hole radiation particles can carry information, so that the information is conserved during the black hole radiation process. The series of research on black hole information loss problem reveals that information conservation remains true when gravitational correlations among Hawking radiations are properly taken into account. Information conservation principle thus states Hawking radiation is unitary, which shows that the dynamics of a black hole obey the laws of quantum mechanics. Since a black hole is a result of general relativity, the unitarity of a black hole definitely indicates the possibility of a unified gravity and quantum mechanics.

Hawking Non-thermal and Purely Thermal Radiations of Rotating Black Hole in Anti-de Sitter Space Time by Hamilton-Jacobi Method

We have explored Hawking non-thermal and purely thermal radiations of Kerr-anti-de Sitter (KAdS) black hole using massive particles tunneling method by taking into account the space time background as dynamical, energy and angular momentum as conserved incorporating the selfgravitation effect of the emitted particles. The results we have obtained for KAdS black hole have shown that the tunneling rates are related to the change of Bekenstein-Hawking entropy and the derived emission spectrum deviates from the pure thermal spectrum and also the obtaining results for KAdS black hole are accordant with Parikh and Wilczek’s opinion and gives a correction to the Hawking radiation of KAdS black hole.GANIT J. Bangladesh Math. Soc.Vol. 37 (2017) 99-109

Neutron imaging with fission and thermal neutrons at NECTAR at MLZ

The instrument NECTAR is located at beam port SR10 of the neutron source FRM II at the Heinz Maier-Leibnitz Zentrum (MLZ). With a pair of moveable uranium plates placed in front of the entrance window of the beam tube, a fission neutron spectrum with a mean energy of 1.9 MeV can be used for neutron imaging applications. Via remote control these plates can be removed and a thermal neutron spectrum (mean energy at 28 meV) gets available for experiments. While the fission neutron spectrum is regularly used, some upgrades of the instrument are necessary to make the thermal neutron spectrum routinely available for user experiments. This includes additional equipment like a new sample stage and a second detector system foreseen to extend the capabilities of NECTAR. The current state of the instrumentation and necessary changes for the future thermal beam option and its usage for standard user experiments will be presented. First measurements were carried out with a temporary flight tube installed and a compact detector (510 mm × 180 mm x 180 mm) for thermal neutrons with a spatial resolution in the range of 100 μm. The feasibility of the thermal beam option could already be verified at an L/D ratio of 240 and a thermal neutron flux of 7.92·106 cm−2 s−1. The thermal neutron beam option adds a pure thermal neutron spectrum – Maxwell spectrum originating from the moderator without alteration by a secondary source or converter – to the energy ranges available for neutron imaging at MLZ instruments. It also offers a unique possibility to combine two quite different neutron energy ranges at a single instrument including their respective advantages. The thermal neutron beam option is funded by BMBF in the frame of research project 05K16VK3.

Quantum Gravity Effects on Hawking Radiation of Schwarzschild-de Sitter Black Holes

The correction of Hawking temperature of Schwarzschild-de Sitter (SdS) black hole is investigated using the generalized Klein-Gordon equation and the generalized Dirac equation by taking the quantum gravity effects into account. We derive the corrected Hawking temperatures for scalar particles and fermions crossing the event horizon. The quantum gravity effects prevent the rise of temperature in the SdS black hole. Besides correction of Hawking temperature, the Hawking radiation of SdS black hole is also investigated using massive particles tunneling method. By considering self gravitation effect of the emitted particles and the space time background to be dynamical, it is also shown that the tunneling rate is related to the change of Bekenstein-Hawking entropy and small correction term (1 + 2β m 2). If the energy and the angular momentum are taken to be conserved, the derived emission spectrum deviates from the pure thermal spectrum. This result gives a correction to the Hawking radiation and is also in agreement with the result of Parikh and Wilczek.

Statistical Entropy of Black Hole without Truncation Factor

The scatting probability of scalar particles near the event horizon is obtained by solving Klein-Gordon equation in curved space-time. By considering the reaction of a black hole radiation in space-time background, we find that Hawking radiation is not a strictly pure thermal-spectrum and scatting probability is related to the B-H entropy change of black hole. The statistical entropy of black hole is calculated based on the relations between entropy and thermodynamic probability of a macroscopic state in statistical equilibrium. The results show that the statistical entropy of black hole without using any truncation factor is proportional to the area of event horizon.

Hawking radiation via tunneling from a d-dimensional black hole in Gauss–Bonnet gravity

We extend the Parikh–Wilczek method from Einstein gravity spacetime to Gauss–Bonnet modified gravity and study the tunneling radiation of particles across the event horizon of a d-dimensional Gauss–Bonnet Anti de-Sitter black hole. The emission rate of a particle is calculated. It is shown that the emission rate of massive particles takes the same functional form as that of massless particles although that their motion equations tunneling across the horizon are different. It is also shown that the emission spectrum deviates from the pure thermal spectrum but is consistent with an underlying unitary theory. In addition, significant but interesting phenomenon is demonstrated when Gauss–Bonnet term is present. The expression of the emission rate for a black hole in Gauss–Bonnet gravity differs from that for a black hole in Einstein gravity. After adopting the conventional tunneling rate, we obtain the expression of the entropy of the Gauss–Bonnet black hole, which is in accordance with the early results but does not obey the area law. So the research of tunneling radiation in this paper may serve as a new perspective of understanding the thermodynamics of black holes in Gauss–Bonnet gravity.

The Thermal Neutron Beam Option for NECTAR at MLZ

The beam port SR10 at the neutron source FRM II of Heinz Maier-Leibnitz Zentrum (MLZ) is equipped with a moveable assembly of two uranium plates, which can be placed in front of the entrance window of the beam tube via remote control. With these plates placed in their operating position the thermal neutron spectrum produced by the neutron source FRM II is converted to fission neutrons with 1.9 MeV of mean energy. This fission neutron spectrum is routinely used for medical applications at the irradiation facility MEDAPP, for neutron radiography and tomography experiments at the facility NECTAR and for materials testing. If, however, the uranium plates are in their stand-by position far off the tip of the beam tube and the so-called permanent filter for thermal neutrons is removed, thermal neutrons originating from the moderator tank enter the beam tube and a thermal spectrum becomes available for irradiation or activation of samples. By installing a temporary flight tube the beam may be used for thermal neutron radiography and tomography experiments at NECTAR. The thermal neutron beam option not only adds a pure thermal neutron spectrum to the energy ranges available for neutron imaging at MLZ instruments but it also is an unique possibility to combine two quite different neutron energy ranges at a single instrument including their respective advantages.The thermal neutron beam option for NECTAR is funded by BMBF in frame of research project 05K16VK3.

X-ray Analysis of the Pulsar Wind Nebula DA 495 and its Central Object

We report the results of a simultaneous analysis of the Chandra and XMM- Newton data on the pulsar wind nebula DA 495 and its central object, J1952.2+2925, which is presumably a pulsar. The J1952.2+2925 pure thermal spectrum can be equally well described either by the blackbody model with a temperature of 215 eV and an emitting area radius of 0.6 km or magnetized neutron star atmosphere models with temperatures of 80-90 eV. We also used the high temporal resolution XMM-Newton/EPIC-pn data to search for pulsations from J1952.2+2925. No pulsations were found so we set an upper limit for the pulsed fraction which is 40%. Using of the interstellar absorption-distance relation allowed us to estimate the distance to DA 495, which lies between 1 and 5 kpc.

DEEP OPTICAL OBSERVATIONS OF UNUSUAL NEUTRON STAR CALVERA WITH THE GTC∗

ABSTRACT Calvera is an unusual, isolated neutron star with a pure thermal X-ray spectrum typical of central compact objects in supernova remnants. On the other hand, its rotation period and spin-down rate are typical of ordinary rotation-powered pulsars. It was discovered and studied through X-rays, and has not yet been detected in other spectral domains. We present deep optical imaging of the Calvera field, obtained with the Gran Telescopio Canarias, in the and bands. Within the vicinity of of Calvera, we detected two point-like objects that were invisible at previous shallow observations. However, accurate astrometry showed that neither of them can be identified with the pulsar. We put new upper limits of and on its optical brightness. We also reanalyzed all available archival X-ray data on Calvera. Comparison of the Calvera thermal emission parameters and upper limits on optical and non-thermal X-ray emission with respective data on rotation-powered pulsars shows that Calvera might belong to the class of ordinary middle-aged pulsars, if we assume that its distance is in the range of 1.5–5 kpc.

Tunneling radiation as new perspective of understanding the thermodynamics in f ( R ) $f(R)$ gravity

We use the Parikh-Wilczek method to study the tunneling radiation from the event horizon of a charged AdS black hole in \(f(R)\) gravity. The emission rate of a particle is calculated. The emission spectrum deviates from the pure thermal spectrum but consists with an underlying unitary theory. The emission rate of massive particles takes the same functional form as that of massless particles. Contradictory but interesting phenomenon is discovered. The expression of the emission rate for a black hole in \(f(R)\) gravity differs from that for a black hole in Einstein gravity, if the area-law of the black hole entropy is insisted on. Conversely, based on abandoning the area-law and admitting the conventional tunneling rate, we obtain the expressions of the entropy and the first law of thermodynamics for the \(f(R)\) gravity black hole, which is in accordance with the early results. So the research of tunneling radiation in this paper may serve as a new perspective of understanding the thermodynamics of black holes in \(f(R)\) gravity.

The third order correction on Hawking radiation and entropy conservation during black hole evaporation process

Abstract Using Parikh–Wilczek tunneling framework, we calculate the tunneling rate from a Schwarzschild black hole under the third order WKB approximation, and then obtain the expressions for emission spectrum and black hole entropy to the third order correction. The entropy contains four terms including the Bekenstein–Hawking entropy, the logarithmic term, the inverse area term, and the square of inverse area term. In addition, we analyse the correlation between sequential emissions under this approximation. It is shown that the entropy is conserved during the process of black hole evaporation, which consists with the request of quantum mechanics and implies the information is conserved during this process. We also compare the above result with that of pure thermal spectrum case, and find that the non-thermal correction played an important role.

Constraining the parameters of the pulsar wind nebula DA 495 and its pulsar withChandraandXMM–Newton

We present spectral and timing analyses of the X-ray emission from the pulsar wind nebula DA 495 and its central object, J1952.2+2925, suggested to be the pulsar, using archival Chandra and XMM-Newton data. J1952.2+2925 has a pure thermal spectrum which is equally well fitted either by the blackbody model with a temperature of $\approx 215$ eV and an emitting area radius of $\approx 0.6$ km or by magnetized neutron star atmosphere models with temperatures of 80-90 eV. In the latter case the thermal emission can come from the entire neutron star surface which temperature is consistent with standard neutron star cooling scenarios. We place also an upper limit on the J1952.2+2925 nonthermal flux. The derived spectral parameters are generally compatible with published ones based only on the Chandra data, but they are much more accurate due to the inclusion of XMM-Newton data. No pulsations were found and we placed an upper limit for the J1952.2+2925 pulsed emission fraction of 40 per cent. Utilizing the interstellar absorption-distance relation, we estimated the distance to DA 495, which can be as large as 5 kpc if J1952.2+2925 emission is described by the atmosphere models. We compiled possible multi-wavelength spectra of the nebula including radio data; they depend on the spectral model of the central object. Comparing the results with other pulsar plus wind nebula systems we set reasonable constraints on the J1952.2+2925 spin-down luminosity and age. We suggest that the Fermi source 3FGL J1951.6+2926 is the likely $\gamma$-ray counterpart of J1952.2+2925.

On Hawking Radiation from a Charged Black Hole of Heterotic String Theory

We investigate the Hawking radiation of a GMGHS charged black hole from the heterotic string scenario by the massive particles tunneling method. We consider the spacetime background to be dynamical, incorporate the self-gravitation effect of the emitted particles and show that the tunneling rate is related to the change of Bekenstein–Hawking entropy and the derived emission spectrum does not deviate from the pure thermal spectrum of Schwrzschild's black hole.

Hawking non-thermal and thermal radiations of Reissner Nordström anti-de Sitter black hole by Hamilton-Jacobi method

In Refs. (M. Atiqur Rahman, M. Ilias Hossain (2012) Phys. Lett. B {\bf 712} 1), we have developed Hamilton-Jacobi method for dynamical spacetime and discussed Hawking radiation of Schwarzschild-de Sitter black hole by massive particle tunneling method. In this letter, we have investigated the hawking purely thermal and nonthermal radiations of Reissner-Nordstr\"{o}m-de Sitter (RNdS) black hole. We have considered energy and angular momentum as conserved and shown that the tunneling rate is related to the change of Bekenstein-Hawking entropy and the derived emission spectrum deviates from the pure thermal spectrum. The results we have obtained for RNdS black hole is also in accordance with Parikh and Wilczek\rq s opinion and recovered the new result for Hawking radiation of RNdS black hole.

Hawking non-thermal and thermal radiations of Schwarzschild anti-de Sitter black hole by Hamilton-Jacobi method

The massive particles tunneling method has been used to investigate the Hawking non-thermal and purely thermal radiations of Schwarzschild Anti-de Sitter (SAdS) black hole. Considering the spacetime background to be dynamical, incorporate the self-gravitation effect of the emitted particles the imaginary part of the action has been derived from Hamilton-Jacobi equation. Using the conservation laws of energy and angular momentum we have showed that the non-thermal and purely thermal tunneling rates are related to the change of Bekenstein-Hawking entropy and the derived emission spectrum deviates from the pure thermal spectrum. The result obtained for SAdS black hole is also in accordance with Parikh and Wilczek\rq s opinion and gives a correction to the Hawking radiation of SAdS black hole.

Suzaku Observations of Abell 1555 and Abell 1558: Searching for Non-Thermal Emission from Large-Scale Structure Formation

We report on X-ray observations of two galaxy clusters, Abell 1555 and Abell 1558, with Suzaku, which are included in a large-scale filamentary structure and a supercluster, to search for non-thermal emission driven by shocks produced during structure formation. These two clusters were detected by Suzaku/XIS for the first time in the X-ray band of 0.5–7 keV. No significant flux has been detected by HXD in the energy band of 13–40 keV, and upper limits are reported. From an analysis of the XIS data, we found that the spectrum of A 1555 could be fit by a thermal plus power-law model, significantly better than a single-temperature pure thermal spectrum. If this power-law component is due to inverse-Compton scattering, the fraction of the total baryon energy imparted to non-thermal electrons is consistent with the typical value inferred from observations of other clusters. However, other scenarios (e.g., underlying AGNs, multi-temperature thermal models) cannot be excluded, and further investigation of this system is desired. Basic physical properties of A 1555 (e.g., total mass) are also reported.