High-Frequency and Type-C QPOs from Oscillating, Precessing Hot, Thick Flow

Motivated by recent studies showing an apparent correlation between the high-frequency quasi-periodic oscillations (QPOs) and the low-frequency, type-C QPO in low-mass, black hole X-ray binaries (LMXBs), we explore a model that explains all three QPOs in terms of an oscillating, precessing hot flow in the truncated-disk geometry. Our model favors attributing the two high-frequency QPOs, often occurring in a near 3:2 frequency ratio, to the breathing and vertical epicyclic frequency modes of the hot, thick flow, although we can not rule out the Keplerian and m=-1 radial epicyclic modes. In either case, the type-C QPO is attributed to precession. The correlation of the QPOs comes from the fact that all three frequencies are associated with the same geometrical structure. While the exact QPO frequencies are sensitive to the black hole mass and spin, their evolution over the course of an outburst is mainly tied to the truncation radius between the geometrically thin, optically thick disk and the inner, hot flow. We show that, in the case of the LMXB GRO J1655-40, this model can explain the one simultaneous observation of all three QPOs and that an extrapolation of the model appears to match lower frequency observations where only two of the three components are seen. Thus, this model may be able to unify multiple QPO observations using the properties of a single, simple, geometrical model.Comment: 7 pages, 4 figures, accepted to MNRA

Optical Signal Processing for Manipulating and Characterizing Time-Frequency Entangled Photons.

Time-frequency entangled photons ( biphotons ) exhibit joint spectral and temporal correlations that are unattainable with classical light. Besides being deployed for tests of quantum nonlocality, these photonic states are desirable for a unique range of applications that can significantly impact communications and computation. In this dissertation, we describe novel schemes based on spectral and temporal domain processing for manipulating and characterizing broadband biphotons. Implementing frequency-dependent filters, first, we present and demonstrate a technique for controlling the relative delay between a pair of entangled photons, relying on pump frequency tuning and the quantum concept of nonlocal dispersion cancellation. Next, we demonstrate near-field frequency-to-time mapping, a technique adopted from classical photonics, for arbitrary control of biphoton temporal correlations. Subsequently, we generate temporal correlation trains by creating biphoton frequency combs through programmable spectral amplitude shaping and demonstrate the temporal Talbot effect with entangled photons for the first time. Moreover, in the absence of fast single-photon detectors, we show how electro-optic phase modulation (originally a time-dependent operation) can be used to examine the coherence of biphoton frequency combs. Lastly, we introduce a scheme based on electro-optic intensity modulation, another time-domain operation, for improving the resolution in biphoton temporal correlation measurements. Overall, our body of work could provide additional insight into the manipulation and characterization of biphoton states, as well as contribute towards the improvement of quantum technologies

Investigating the mass of the intermediate mass black hole candidate HLX-1 with the SLIMBH model

In this paper we present a comprehensive study of the mass of the intermediate mass black hole candidate HLX-1 in the galaxy ESO 243-49. We analyse the continuum X-ray spectra collected by Swift, XMM-Newton, and Chandra with the slim disc model, SLIMBH, and estimate the black hole mass for the full range of inclination (inc = 0{\deg} - 85{\deg}) and spin (a* = 0 - 0.998). The relativistic SLIMBH model is particularly suited to study high luminosity disc spectra as it incorporates the effects of advection, such as the shift of the inner disc edge towards smaller radii and the increasing height of the disc photosphere (including relativistic ray-tracing from its proper location rather than the mid-plane of the disc). We find for increasing values of inclination that a zero spin black hole has a mass range of 6,300 - 50,900 M_sun and a maximally spinning black hole has a mass between 16,900 - 191,700 M_sun. This is consistent with previous estimates and reinforces the idea that HLX-1 contains an intermediate mass black hole.Comment: updated version, published in Astronomy and Astrophysic

Testing wind as an explanation for the spin problem in the continuum-fitting method

The continuum-fitting method is one of the two most advanced methods of determining the black hole spin in accreting X-ray binary systems. There are, however, still some unresolved issues with the underlying disk models. One of them manifests as an apparent decrease in spin for increasing source luminosity. Here, we perform a few simple tests to establish whether outflows from the disk close to the inner radius can address this problem. We employ four different parametric models to describe the wind and compare these to the apparent decrease in spin with luminosity measured in the sources LMC~X-3 and GRS~1915+105. Wind models in which parameters do not explicitly depend on the accretion rate cannot reproduce the spin measurements. Models with mass accretion rate dependent outflows, however, have spectra that emulate the observed ones. The assumption of a wind thus effectively removes the artifact of spin decrease. This solution is not unique; the same conclusion can be obtained with a truncated inner disk model. To distinguish among valid models, high resolution X-ray data and a realistic description of the Comptonization in the wind will be needed.Comment: 14 pages, 11 figures, accepted by Ap

The Low-Spin Black Hole in LMC X-3

Building upon a new dynamical model for the X-ray binary LMC X-3, we measure the spin of its black hole primary via the continuum-fitting method. We consider over one thousand thermal-state RXTE X-ray spectra of LMC X-3. Using a large subset of these spectra, we constrain the spin parameter of the black hole to be spin = 0.21(+0.18,-0.22), 90% confidence. Our estimate of the uncertainty in spin takes into account a wide range of systematic errors. We discuss evidence for a correlation between a black hole's spin and the complexity of its X-ray spectrum.Comment: Submitted to ApJL, 5 pages emulateapj, 2 figures and 1 tabl

Seasonal pattern of resource conflict between farmers and herdsmen in benue state, nigeria

There is sparse literature on seasonal pattern of farmers and herdsmen conflict in Benue State, Nigeria despite numerous links between climate change and resource conflict. Thus, this study was designed to assess the seasonal occurrence of armed conflict in Benue State and analyze the monthly death casualties of armed conflict in Benue state from 2010-2019. Data were collected from secondary sources such as report of Nigeria Police Force, Nigeria watch data base and Newspapers. Data were presented in tables and analyzed using descriptive statistic such as range, mean, standard deviation and coefficient of variation. Result shows that monthly occurrence of armed conflict ranged from 0-20 times with mean value of 4.92 and 98% coefficient of variation. March has the highest number (20) of armed conflict occurrence followed by April and, then July. October had zero (0) record of armed conflict from 2010-2019. Similarly, the monthly conflict death was higher in dry than rainy season. Monthly death ranged from 0-590 with mean value of 106 deaths and 95 % coefficient of variation. It was concluded that both the frequency and death casualties of resource conflict in Benue State have seasonal pattern and were more in dry than rainy season. Intensification of resolution mechanisms and ranching were recommended

Seasonal pattern of resource conflict between farmers and herdsmen in Benue State, Nigeria

There is sparse literature on seasonal pattern of farmers and herdsmen conflict in Benue State, Nigeria despite numerous links between climate change and resource conflict. Thus, this study was designed to assess the seasonal occurrence of armed conflict in Benue State and analyze the monthly death casualties of armed conflict in Benue state from 2010-2019. Data were collected from secondary sources such as report of Nigeria Police Force, Nigeria watch data base and Newspapers. Data were presented in tables and analyzed using descriptive statistic such as range, mean, standard deviation and coefficient of variation. Result shows that monthly occurrence of armed conflict ranged from 0-20 times with mean value of 4.92 and 98% coefficient of variation. March has the highest number (20) of armed conflict occurrence followed by April and, then July. October had zero (0) record of armed conflict from 2010-2019. Similarly, the monthly conflict death was higher in dry than rainy season. Monthly death ranged from 0-590 with mean value of 106 deaths and 95 % coefficient of variation. It was concluded that both the frequency and death casualties of resource conflict in Benue State have seasonal pattern and were more in dry than rainy season. Intensification of resolution mechanisms and ranching were recommended

Spectra of Puffy Accretion Discs: the kynbb Fit

Puffy disc is a numerical model, expected to capture the properties of the accretion flow in X-ray black hole binaries in the luminous, mildly sub-Eddington state. We fit the kerrbb and kynbb spectral models in XSPEC to synthetic spectra of puffy accretion discs, obtained in general relativistic radiative magnetohydrodynamic simulations, to see if they correctly recover the black hole spin and mass accretion rate assumed in the numerical simulation. We conclude that neither of the two models is capable of correctly interpreting the puffy disc parameters, which highlights a necessity to develop new, more accurate, spectral models for the luminous regime of accretion in X-ray black hole binaries. We propose that such spectral models should be based on the results of numerical simulations of accretion.Comment: 6 pages, 4 figures, submitted to the AN as proceedings of XMM-Newton 2022 Science Worksho

Determinant factors of resource conflict between farmers and herdsmen in Benue State, Nigeria

The determinant factors of resource conflict between farmers and herdsmen in Benue State were analysed. Objectives were to assess the prevalence of resource conflict factors in Benue state and determine factors most responsible for the resource conflict in Benue state. Field survey of three hundred and eighty-two (382) residents was conducted using questionnaire, interview and focus group discussion. Data collected were analyzed using percentage and Factor Analysis. Results showed that factors such as drought, flood, erosion, pollution, politics, greed, proliferation of arms, religion, tribalism, expansion of farmland, increases in herds, poverty, unemployment, cattle rustling, destruction of crops by herds, population growth and urbanization are responsible for the conflict. However, further, analysis of result shows that only 1.38% of respondents posited that environmental/climatic factors, 30% economic factors, 32.78% greed/insecurity, 13.75% and 22.08% posited cultural and population factors respectively. It was concluded that human factors such as economic, greed/insecurity, cultural and population are the major drivers of the resource conflict between farmers and herdsmen than environmental factors like erosion, flood and draught. promote skill acquisition and create jobs to engage youths to boast the economy and reduce conflict