X-rays from Warped Black Hole Accretion Disks

In this thesis, I present the results from my research to better understand accretion onto black holes and neutron stars based on spectropolarimetric X-ray observations. I have developed a general relativistic ray-tracing code which simulates X-rays from warped accretion disks around black holes. I used this to predict the polarization of the thermal X-ray emission and the energy spectrum the reflected power law emission. Both of these can be used to measure properties of black hole systems, such as the spin parameter and the inclination of the observer to its spin axis. My results enable the measurement of these parameters with improved accuracies and with a different set of systematic errors. The methods discussed can be applied to the data of existing X-ray satellites, such as Chandra and XMM-Newton, and upcoming spaceborne missions, such as the Imaging X-ray Polarimetry Explorer (IXPE) and the X-ray Imaging and Spectroscopy Mission (XRISM). My work also included optimization and deployment of the balloon-borne X-Calibur experiment for its 2018/2019 long duration balloon flight from McMurdo, Antarctica. Results from this flight allowed me to study the light curve and polarization of the hard X-ray emission from the accreting pulsar GX 301-2. I have also contributed to the research and development for its successor, called XL-Calibur, which will observe pulsars and black holes during a northern hemisphere flight in the next few years

Thermodynamic analysis of high-temperature pumped thermal energy storage systems: Refrigerant selection, performance and limitations

[EN] One of the bottlenecks for a wider implementation of renewable energies is the development of efficient energy storage systems which can compensate for the intermittency of renewable energy sources. Pumped thermal energy storage (PTES) is a very recent technology that can be a promising site-independent alternative to pumped hydro energy storage or compressed air energy storage, without the corresponding geological and environmental restrictions. Accordingly, this paper presents a full thermodynamic analysis of a PTES system consisting of a high-temperature heat pump (HTHP), which drives an organic Rankine cycle (ORC) by means of an intermediate high-temperature thermal energy storage system (HT-TES). The latter combines both latent and sensible heat thermal energy storage sub-systems to maximize the advantage of the refrigerant subcooling. After validating the proposed model, several parametric studies have been carried out to assess the system performance using different refrigerants and configurations, under a wide range of source and sink temperatures. The results show that for a system that employs the same refrigerant in both the HTHP and ORC, and for a latent heat thermal energy storage system at 133 degrees C, R-1233zd(E) and R-1234ze(Z) present the best performance. Among all the cases studied with a latent heat thermal energy storage system at 133 degrees C, the best system performance, also considering the impact on the environment, has been achieved employing R-1233zd(E) in the HTHP and Butene in the ORC. Such a system can theoretically reach a power ratio of 1.34 under HTHP source and ORC sink temperatures of 100 and 25 degrees C, respectively. (C) 2020 Published by Elsevier Ltd.This work has been partially funded by the grant agreement No. 764042 (CHESTER project) of the European Union's Horizon 2020 research and innovation program.Hassan, A.; O'donoghue, L.; Sánchez Canales, V.; Corberán, JM.; Payá-Herrero, J.; Jockenhoefer, H. (2020). Thermodynamic analysis of high-temperature pumped thermal energy storage systems: Refrigerant selection, performance and limitations. Energy Reports. 6(7):147-159. https://doi.org/10.1016/j.egyr.2020.05.010S14715967Abarr, M., Geels, B., Hertzberg, J., & Montoya, L. D. (2017). Pumped thermal energy storage and bottoming system part A: Concept and model. Energy, 120, 320-331. doi:10.1016/j.energy.2016.11.089Abarr, M., Hertzberg, J., & Montoya, L. D. (2017). Pumped Thermal Energy Storage and Bottoming System Part B: Sensitivity analysis and baseline performance. Energy, 119, 601-611. doi:10.1016/j.energy.2016.11.028Aneke, M., & Wang, M. (2016). Energy storage technologies and real life applications – A state of the art review. Applied Energy, 179, 350-377. doi:10.1016/j.apenergy.2016.06.097Arpagaus, C., Bless, F., Uhlmann, M., Schiffmann, J., & Bertsch, S. S. (2018). High temperature heat pumps: Market overview, state of the art, research status, refrigerants, and application potentials. Energy, 152, 985-1010. doi:10.1016/j.energy.2018.03.166BP plc, 2018. BP Statistical Review of World Energy. London.Budt, M., Wolf, D., Span, R., & Yan, J. (2016). A review on compressed air energy storage: Basic principles, past milestones and recent developments. Applied Energy, 170, 250-268. doi:10.1016/j.apenergy.2016.02.108Cheayb, M., Marin Gallego, M., Tazerout, M., & Poncet, S. (2019). Modelling and experimental validation of a small-scale trigenerative compressed air energy storage system. Applied Energy, 239, 1371-1384. doi:10.1016/j.apenergy.2019.01.222Pereira da Cunha, J., & Eames, P. (2016). Thermal energy storage for low and medium temperature applications using phase change materials – A review. Applied Energy, 177, 227-238. doi:10.1016/j.apenergy.2016.05.097European Comission, 2018. A Clean Planet for all. A European strategic long-term vision for a prosperous, modern, competitive and climate neutral economy. Brussels.European Council, 2014. European Council 23/24 2014 - Conclusions. Brussels.Fan, J., Xie, H., Chen, J., Jiang, D., Li, C., Ngaha Tiedeu, W., & Ambre, J. (2020). Preliminary feasibility analysis of a hybrid pumped-hydro energy storage system using abandoned coal mine goafs. Applied Energy, 258, 114007. doi:10.1016/j.apenergy.2019.114007Frate, G. F., Antonelli, M., & Desideri, U. (2017). A novel Pumped Thermal Electricity Storage (PTES) system with thermal integration. Applied Thermal Engineering, 121, 1051-1058. doi:10.1016/j.applthermaleng.2017.04.127Guo, J., Cai, L., Chen, J., & Zhou, Y. (2016). Performance optimization and comparison of pumped thermal and pumped cryogenic electricity storage systems. Energy, 106, 260-269. doi:10.1016/j.energy.2016.03.053Jockenhöfer, H., Steinmann, W.-D., & Bauer, D. (2018). Detailed numerical investigation of a pumped thermal energy storage with low temperature heat integration. Energy, 145, 665-676. doi:10.1016/j.energy.2017.12.087Kusakana, K. (2019). Hydro aeropower for sustainable electricity cost reduction in South African farming applications. Energy Reports, 5, 1645-1650. doi:10.1016/j.egyr.2019.11.023Laughlin, R. B. (2017). Pumped thermal grid storage with heat exchange. Journal of Renewable and Sustainable Energy, 9(4), 044103. doi:10.1063/1.4994054Lecompte, S., Huisseune, H., van den Broek, M., Vanslambrouck, B., & De Paepe, M. (2015). Review of organic Rankine cycle (ORC) architectures for waste heat recovery. Renewable and Sustainable Energy Reviews, 47, 448-461. doi:10.1016/j.rser.2015.03.089Liu, J.-L., & Wang, J.-H. (2016). A comparative research of two adiabatic compressed air energy storage systems. Energy Conversion and Management, 108, 566-578. doi:10.1016/j.enconman.2015.11.049Ma, T., Yang, H., & Lu, L. (2014). Feasibility study and economic analysis of pumped hydro storage and battery storage for a renewable energy powered island. Energy Conversion and Management, 79, 387-397. doi:10.1016/j.enconman.2013.12.047McTigue, J. D., White, A. J., & Markides, C. N. (2015). Parametric studies and optimisation of pumped thermal electricity storage. Applied Energy, 137, 800-811. doi:10.1016/j.apenergy.2014.08.039Navarro-Peris, E., Corberán, J. M., Falco, L., & Martínez-Galván, I. O. (2013). New non-dimensional performance parameters for the characterization of refrigeration compressors. International Journal of Refrigeration, 36(7), 1951-1964. doi:10.1016/j.ijrefrig.2013.07.007Steinmann, W. D. (2014). The CHEST (Compressed Heat Energy STorage) concept for facility scale thermo mechanical energy storage. 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Observations of a GX 301-2 Apastron Flare with the X-Calibur Hard X-Ray Polarimeter Supported by NICER, the Swift XRT and BAT, and Fermi GBM

The accretion-powered X-ray pulsar GX 301-2 was observed with the balloon-borne X-Calibur hard X-ray polarimeter during late December 2018, with contiguous observations by the NICER X-ray telescope, the Swift X-ray Telescope and Burst Alert Telescope, and the Fermi Gamma-ray Burst Monitor spanning several months. The observations detected the pulsar in a rare apastron flaring state coinciding with a significant spin-up of the pulsar discovered with the Fermi GBM. The X-Calibur, NICER, and Swift observations reveal a pulse profile strongly dominated by one main peak, and the NICER and Swift data show strong variation of the profile from pulse to pulse. The X-Calibur observations constrain for the first time the linear polarization of the 15-35 keV emission from a highly magnetized accreting neutron star, indicating a polarization degree of (27+38-27)% (90% confidence limit) averaged over all pulse phases. We discuss the spin-up and the X-ray spectral and polarimetric results in the context of theoretical predictions. We conclude with a discussion of the scientific potential of future observations of highly magnetized neutron stars with the more sensitive follow-up mission XL-Calibur

Performance of the X-Calibur Hard X-Ray Polarimetry Mission during its 2018/19 Long-Duration Balloon Flight

X-Calibur is a balloon-borne telescope that measures the polarization of high-energy X-rays in the 15--50keV energy range. The instrument makes use of the fact that X-rays scatter preferentially perpendicular to the polarization direction. A beryllium scattering element surrounded by pixellated CZT detectors is located at the focal point of the InFOC{\mu}S hard X-ray mirror. The instrument was launched for a long-duration balloon (LDB) flight from McMurdo (Antarctica) on December 29, 2018, and obtained the first constraints of the hard X-ray polarization of an accretion-powered pulsar. Here, we describe the characterization and calibration of the instrument on the ground and its performance during the flight, as well as simulations of particle backgrounds and a comparison to measured rates. The pointing system and polarimeter achieved the excellent projected performance. The energy detection threshold for the anticoincidence system was found to be higher than expected and it exhibited unanticipated dead time. Both issues will be remedied for future flights. Overall, the mission performance was nominal, and results will inform the design of the follow-up mission XL-Calibur, which is scheduled to be launched in summer 2022.Comment: 19 pages, 31 figures, submitted to Astropart. Phy

Discovering the highest energy neutrinos with the Payload for Ultrahigh Energy Observations (PUEO)

The Payload for Ultrahigh Energy Observations (PUEO) is a NASA Long-Duration Balloon Mission that has been selected for concept development. PUEO has unprecedented sensitivity to ultra-high energy neutrinos above 1018 eV. PUEO will be sensitive to both Askaryan emission from neutrino-induced cascades in Antarctic ice and geomagnetic emission from upward-going air showers that are a result of tau neutrino interactions. PUEO is also especially well-suited for point source and transient searches. Compared to its predecessor ANITA, PUEO achieves better than an order-of-magnitude improvement in sensitivity and lowers the energy threshold for detection, by implementing a coherent phased array trigger, adding more channels, optimizing the detection bandwidth, and implementing real-time filtering. Here we discuss the science reach and plans for PUEO, leading up to a 2024 launch

The Payload for Ultrahigh Energy Observations (PUEO): a white paper

The Payload for Ultrahigh Energy Observations (PUEO) long-duration balloon experiment is designed to have world-leading sensitivity to ultrahigh-energy neutrinos at energies above 1 EeV. Probing this energy region is essential for understanding the extreme-energy universe at all distance scales. PUEO leverages experience from and supersedes the successful Antarctic Impulsive Transient Antenna (ANITA) program, with an improved design that drastically improves sensitivity by more than an order of magnitude at energies below 30 EeV. PUEO will either make the first significant detection of or set the best limits on ultrahigh-energy neutrino fluxes

The Payload for Ultrahigh Energy Observations (PUEO): A White Paper

The Payload for Ultrahigh Energy Observations (PUEO) long-duration balloon experiment is designed to have world-leading sensitivity to ultrahigh-energy neutrinos at energies above 1 EeV. Probing this energy region is essential for understanding the extreme-energy universe at all distance scales. PUEO leverages experience from and supersedes the successful Antarctic Impulsive Transient Antenna (ANITA) program, with an improved design that drastically improves sensitivity by more than an order of magnitude at energies below 30 EeV. PUEO will either make the first significant detection of or set the best limits on ultrahigh-energy neutrino fluxes.Comment: 37 pages, 17 figures. Minor updates, version submitted to JINS

Using X-Ray Polarimetry to Probe the Physics of Black Holes and Neutron Stars

This white paper highlights compact object and fundamental physics science opportunities afforded by high-throughput broadband (0.1-60 keV) X-ray polarization observations. The polarimetric observations can reveal the inner workings of high-energy sources, and allow us to test physical laws in the extreme conditions close to compact objects

Modeling Pumped Thermal Energy Storage with Waste Heat Harvesting

This work introduces a new concept for a utility scale combined energy storage and generation system. The proposed design utilizes a pumped thermal energy storage (PTES) system, which also utilizes waste heat leaving a natural gas peaker plant. This system creates a low cost utility-scale energy storage system by leveraging this dual-functionality. This dissertation first presents a review of previous work in PTES as well as the details of the proposed integrated bottoming and energy storage system. A time-domain system model was developed in Mathworks R2016a Simscape and Simulink software to analyze this system. Validation of both the fluid state model and the thermal energy storage model are provided. The experimental results showed the average error in cumulative fluid energy between simulation and measurement was +/- 0.3% per hour. Comparison to a Finite Element Analysis (FEA) model showed \u3c1% error for bottoming mode heat transfer. The system model was used to conduct sensitivity analysis, baseline performance, and levelized cost of energy of a recently proposed Pumped Thermal Energy Storage and Bottoming System (Bot-PTES) that uses ammonia as the working fluid. This analysis focused on the effects of hot thermal storage utilization, system pressure, and evaporator/condenser size on the system performance. This work presents the estimated performance for a proposed baseline Bot-PTES. Results of this analysis showed that all selected parameters had significant effects on efficiency, with the evaporator/condenser size having the largest effect over the selected ranges. Results for the baseline case showed stand-alone energy storage efficiencies between 51 and 66% for varying power levels and charge states, and a stand-alone bottoming efficiency of 24%. The resulting efficiencies for this case were low compared to competing technologies; however, the dual-functionality of the Bot-PTES enables it to have higher capacity factor, leading to $91-197/MWh levelized cost of energy compared to$262-284/MWh for batteries and $172-254/MWh for Compressed Air Energy Storage