Astrophysics and Astronomy Commons^™

A B-Polynomial Approach To Approximate Solutions Of Pdes With Multiple Initial Conditions, Muhammad I. Bhatti, Md. Habibur Rahman

Physics & Astronomy Faculty Publications

In this article, we present a novel B-Polynomial Approach for approximating solutions to partial differential equations (PDEs), addressing the multiple initial conditions. Our method stands out by utilizing two-dimensional Bernstein polynomials (B-polynomials) in conjunction with their operational matrices to effectively manage the complexity associated with PDEs. This approach not only enhances the accuracy of solutions but also provides a structured framework for tackling various boundary conditions. The PDE is transformed into a system of algebraic equations, which are then solved to approximate the PDE solution. The process is divided into two main steps: First, the PDE is integrated to incorporate …

A Class Of Stable Nonlinear Non-Hermitian Skin Modes, Hamed Ghaemi-Dizicheh

Physics & Astronomy Faculty Publications

The non-Hermitian skin effect (NHSE) is a well-known phenomenon in open topological systems that causes a large number of eigenstates to become localized at the boundary. Although many aspects of its theory have been investigated in linear systems, this phenomenon remains novel in nonlinear models. In the first step of this paper, we look at the conditions for the presence of quasi-skin modes in a semi-infinite, one-dimensional, nonlinear, nonreciprocal lattice. In the following phase, we explore the survival time of the quasi-skin mode in a finite nonlinear lattice with open edges. We study the dependency of the survival time on …

A Class Of Stable Nonlinear Non-Hermitian Skin Modes, Hamed Ghaemi-Dizicheh

Physics & Astronomy Faculty Publications

The non-Hermitian skin effect (NHSE) is a well-known phenomenon in open topological systems that causes a large number of eigenstates to become localized at the boundary. Although many aspects of its theory have been investigated in linear systems, this phenomenon remains novel in nonlinear models. In the first step of this paper, we look at the conditions for the presence of quasi-skin modes in a semi-infinite, one-dimensional, nonlinear, nonreciprocal lattice. In the following phase, we explore the survival time of the quasi-skin mode in a finite nonlinear lattice with open edges. We study the dependency of the survival time on …

Computational And Experimental Data For Undoped And Er-Doped Lithium Tantalate Nanofluorescent Probes, Mkhitar A. Hobosyan, Andrea Pelayo Carvajal, Bhupendra B. Srivastava, Tamanna Zakia, Mohammed Jasim Uddin, Karen S. Martirosyan, Eric Rodriguez, Kofi Nketia Ackaah-Gyasi, Nicholas Dimakis

Physics & Astronomy Faculty Publications

The density functional theory (DFT) and experimental data presented in this paper refer to the research article “Computational and experimental study on undoped and Er-doped lithium tantalate nano fluorescent probes”. The DFT data contain electronic and optical properties for both LiTaO3 and LiTaO3:Er+3, with Er+3 occupying either Li or Ta sites at 4.167 mol. %. All these properties were calculated at the generalized gradient approximation (GGA) limit. Additionally, electronic information was calculated using the hybrid functional by Heyd, Scuseria, and Ernzerho (HSE06), which accurately predicts the location in energy for all Er-4f orbitals. We also include simulated X-ray near edge …

Search For Eccentric Black Hole Coalescences During The Third Observing Run Of Ligo And Virgo, A. G. Abac, R. Abbott, H. Abe, Teviet Creighton, Mario C. Diaz, Francisco Llamas Villarreal, Soma Mukherjee, Gaukhar Nurbek, Volker Quetschke, Wenhui Wang

Physics & Astronomy Faculty Publications

Despite the growing number of binary black hole coalescences confidently observed through gravitational waves so far, the astrophysical origin of these binaries remains uncertain. Orbital eccentricity is one of the clearest tracers of binary formation channels. Identifying binary eccentricity, however, remains challenging due to the limited availability of gravitational waveforms that include the effects of eccentricity. Here, we present observational results for a waveform-independent search sensitive to eccentric black hole coalescences, covering the third observing run (O3) of the LIGO and Virgo detectors. We identified no new high-significance candidates beyond those that have already been identified with searches focusing on …

The First Joint Observation By Kagra With Geo 600, N. Uchikata, R. Abbott, H. Abe, Teviet Creighton, Mario C. Diaz, Francisco Llamas, Soma Mukherjee, Gaukhar Nurbek, Volker Quetschke, Wenhui Wang

Physics & Astronomy Faculty Publications

KAGRA conducted its first joint observation with GEO 600 for two weeks in April, 2020. We performed two types of all-sky searches and two searches dedicated to gravitational wave signals associated with gamma-ray burst events observed during the run. We did not detect any gravitational wave signals, which was expected given the sensitivity of both detectors at that time. However, we did confirm that several search pipelines used in the LIGO-Virgo-KAGRA collaborations worked effectively on the KAGRA data. In this presentation we will report on the data quality of detectors and the search results.

Search For Core Collapse Supernovae Signals In Ligo’S Third Observation Run Using A Network Of Gravitational Wave Detectors Integrated With A Multiclass Convolutional Neural Network, Shahrear Khan Faisal, Gaukhar Nurbek, Michael Benjamin, Bhawana Sedhai, Soma Mukherjee

Physics & Astronomy Faculty Publications

In the existing body of literature, numerous waveforms of core collapse supernovae (CCSN) have emerged from extensive simulations conducted in high-performance computing facilities globally. These waveforms exhibit distinct characteristics related to their explosion mechanisms, influenced by parameters such as progenitor mass, angular momentum, gravitational wave energy, peak frequency, duration, and equation of state. Core collapse supernovae stand out as highly anticipated sources in LIGO’s fourth observation (O4) run, prompting dedicated efforts to detect them. The integration of machine learning, specifically convolutional neural networks (CNN), has become a pivotal avenue for analysis. This study addresses a fundamental query: how can a …

Toi–757 B: An Eccentric Transiting Mini–Neptune On A 17.5–D Orbit, A Alqasim, N Grieves, N M. Rosário, D Gandolfi, J H. Livingston, S Sousa, K A. Collins, J K. Teske, M Fridlund, Ryan J. Oelkers

Physics & Astronomy Faculty Publications

We report the spectroscopic confirmation and fundamental properties of TOI 757 b, a mini Neptune on a 17.5 d orbit transiting a bright star (⁠ mag) discovered by the TESS mission. We acquired high precision radial velocity measurements with the HARPS, ESPRESSO, and PFS spectrographs to confirm the planet detection and determine its mass. We also acquired space borne transit photometry with the CHEOPS space telescope to place stronger constraints on the planet radius, supported with ground based LCOGT photometry. WASP and KELT photometry were used to help constrain the stellar rotation period. We also determined the fundamental parameters of …

Value Creation In A Pedagogically-Focused Faculty Online Learning Community, Fred Goldberg, Edward Price, Mo Basir, Lawrence Escalada, Steve Maier, Steven Sahyun, Tamara D. Snyder, Liang Zeng

Physics & Astronomy Faculty Publications

Faculty online learning communities (FOLCs) can help faculty effectively adopt and persist in using research-based curricula. This paper documents faculty perspectives on the value they gained from participating in a multi-year FOLC designed to help them implement an inquiry-based physical science curriculum. Personal value narratives were collected from 11 volunteer FOLC participants. In the narratives, participants responded to prompts regarding their initial reasons for participation, activities they engaged in, and values they gained, as well as how participation impacted their profession, social connections, professional practice, and ability to influence their world as teachers. Qualitative analysis shows that the values faculty …

Optically Targeted Search For Gravitational Waves Emitted By Core-Collapse Supernovae During The Third Observing Run Of Advanced Ligo And Advanced Virgo, Marek J. Szczepańczyk, Yanyan Zheng, Javier M. Antelis, Michael G. Benjamin, Marie-Anne Bizouard, Alejandro Casallas-Lagos, Pablo Cerda-Duran, Derek Davis, Dorota Gondek-Rosinska, Soma Mukherjee

Physics & Astronomy Faculty Publications

We present the results from a search for gravitational-wave transients associated with core-collapse supernovae observed optically within 30 Mpc during the third observing run of Advanced LIGO and Advanced Virgo. No gravitational wave associated with a core-collapse supernova has been identified. We then report the detection efficiency for a variety of possible gravitational-wave emissions. For neutrino-driven explosions, the distance at which we reach 50% detection efficiency is up to 8.9 kpc, while more energetic magnetorotationally driven explosions are detectable at larger distances. The distance reaches for selected models of the black hole formation, and quantum chromodynamics phase transition are also …

Cosmic Variance Of The Hellings And Downs Correlation For Ensembles Of Universes Having Nonzero Angular Power Spectra, Deepali Agarwal, Joseph D. Romano

Physics & Astronomy Faculty Publications

Gravitational waves (GWs) induce correlated perturbations to the arrival times of pulses from an array of galactic millisecond pulsars. The expected correlations, obtained by averaging over many pairs of pulsars having the same angular separation (pulsar averaging) and over an ensemble of model universes (ensemble averaging), are described by the Hellings and Downs curve. As shown by Allen [Phys. Rev. D 107, 043018 (2023)], the pulsar-averaged correlation will not agree exactly with the expected Hellings and Downs prediction if the gravitational-wave sources interfere with one another, differing instead by a “cosmic variance” contribution. The …

Ultralight Vector Dark Matter Search Using Data From The Kagra O3gk Run, A. Abac, R. Abbott, H. Abe, Teviet Creighton, Mario C. Diaz, Francisco Llamas, Soma Mukherjee, Gaukhar Nurbek, Volker Quetschke, Wenhui Wang

Physics & Astronomy Faculty Publications

Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for U(1)B−L gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the …

A Review Of Stable, Traversable Wormholes In F(R) Gravity Theories, Ramesh Radhakrishnan, Patrick Brown, Jacob Matulevich, Eric Davis, Delaram Mirfendereski, Gerald Cleaver

Physics & Astronomy Faculty Publications

It has been proven that in standard Einstein gravity, exotic matter (i.e., matter violating the pointwise and averaged Weak and Null Energy Conditions) is required to stabilize traversable wormholes. Quantum field theory permits these violations due to the quantum coherent effects found in any quantum field. Even reasonable classical scalar fields violate the energy conditions. In the case of the Casimir effect and squeezed vacuum states, these violations have been experimentally proven. It is advantageous to investigate methods to minimize the use of exotic matter. One such area of interest is extended theories of Einstein gravity. It has been claimed …

Temperature-Dependent Optical Constants Of Vanadium Dioxide Thin Films Deposited On Polar Dielectrics, Imtiaz Ahmad, Satya R. Kachiraju, Sundar Kunwar, Zachary M. Brown, Pinku Roy, Matthew Gaddy, Vladimir Kuryatkov, Yejin Kwon, Ayrton A. Bernussi, Myoung-Hwan Kim

Physics & Astronomy Faculty Publications

Coating polar dielectrics with thin film vanadium dioxide (VO2) enables one to exploit the temperature-dependent phase transition within VO2 to actively tune and modulate surface phonon polaritons at mid-infrared. However, controlling the behavior of such systems requires intimate knowledge of the temperature-dependent optical constants of VO2, which depend greatly on the growth conditions and substrate material. Here, we accurately determine the complex optical constants of VO2 on polar dielectrics across the insulator-to-metal phase transition (IMT) using only normal incident reflectance spectra by analyzing the reflectance with Kramers–Kronig relations and thin film Fresnel equations. This non-ellipsometry technique offers an …

Microwave Spectroscopy And Large Amplitude Motion Of Chlorosulfonic Acid (Clso2oh), Aaron J. Reynolds, Diego E. Rodriguez, Wei Lin, Kenneth R. Leopold

Physics & Astronomy Faculty Publications

The high-resolution rotational spectrum of chlorosulfonic acid (ClSO2OH) has been studied using both broadband and cavity-based Fourier transform microwave spectrometers over the frequency range of 5–18 GHz. a-, b-, and c-type transitions have been recorded for both the 35Cl and 37Cl isotopologues. The observation of c-type lines establishes that the molecule lacks a plane of symmetry and suggests that the OH group can undergo large amplitude motion between equivalent structures. Interconversion between these structures can be achieved via internal rotation through two inequivalent barriers occurring at Cl-S-O-H torsional angles of 0 or 180 degrees. As in …

Observation Of Gravitational Waves From The Coalescence Of A 2.5–4.5 M⊙ Compact Object And A Neutron Star, A. Abac, R. Abbott, I. Abouelfettouh, F. Acernese, Teviet Creighton, Mario C. Diaz, Francisco Llamas, Soma Mukherjee, Volker Quetschke, Wenhui Wang

Physics & Astronomy Faculty Publications

We report the observation of a coalescing compact binary with component masses 2.5–4.5 M⊙ and 1.2–2.0 M⊙ (all measurements quoted at the 90% credible level). The gravitational-wave signal GW230529_181500 was observed during the fourth observing run of the LIGO–Virgo–KAGRA detector network on 2023 May 29 by the LIGO Livingston observatory. The primary component of the source has a mass less than 5 M⊙ at 99% credibility. We cannot definitively determine from gravitational-wave data alone whether either component of the source is a neutron star or a black hole. However, given existing estimates of the maximum neutron star mass, we find …

Answers To Frequently Asked Questions About The Pulsar Timing Array Hellings And Downs Curve, Joseph D. Romano, Bruce Allen

Physics & Astronomy Faculty Publications

We answer frequently asked questions (FAQs) about the Hellings and Downs correlation curve—the ‘smoking-gun’ signature that pulsar timing arrays (PTAs) have detected gravitational waves (GWs). Many of these questions arise from inadvertently applying intuition about the effects of GWs on LIGO-like detectors to the case of pulsar timing, where not all of it applies. This is because Earth-based detectors, like LIGO and Virgo, have arms that are short (km scale) compared to the wavelengths of the GWs that they detect (≈102–104 km). In contrast, PTAs respond to GWs whose wavelengths (tens of light-years) are much shorter than their arms (a …

Glitch Veto Based On Unphysical Gravitational Wave Binary Inspiral Templates, Raghav Girgaonkar, Soumya D. Mohanty

Physics & Astronomy Faculty Publications

Transient signals arising from instrumental or environmental factors, commonly referred to as glitches, constitute the predominant background of false alarms in gravitational wave searches with ground-based detectors. Therefore, effective data analysis methods for vetoing glitch-induced false alarms are crucial to enhancing the sensitivity of a search. We present a veto method for glitches that impact matched filtering-based searches for binary inspiral signals. The veto uses unphysical sectors in the space of chirp time parameters as well as an unphysical extension including negative chirp times to efficiently segregate glitches from gravitational wave signals in data from a single detector. Inhabited predominantly …

Variable Radio Emission Of Neutron Star X-Ray Binary Ser X–1 During Its Persistent Soft State, Eli C. Pattie, Thomas J. Maccarone, Alexandra J. Tetarenko, James C. A. Miller-Jones, Manuel Pichardo Marcano, Liliana E. Rivera Sandoval

Physics & Astronomy Faculty Publications

Ser X–1 is a low-mass neutron star X-ray binary and has been persistently accreting since its discovery in the 1960s. It has always been observed to be in a soft spectral state and has never showed substantial long-term X-ray variability. Ser X–1 has one previous radio observation in the literature in which radio emission was detected during this soft state, which is contrary to the behavior of black hole X-ray binaries. We have recently obtained 10 randomly sampled radio epochs of Ser X–1 in order to further investigate its anomalous soft-state radio emission. Out of 10 epochs, we find 8 …

Calibrating The Global Network Of Gravitational Wave Observatories Via Laser Power Calibration At Nist And Ptb, Dripta Bhattacharjee, Richard Lenox Savage, Rishabh Bajpai, Joseph Betzwieser, Vladimir Bossilkov, Dan Chen, Cervane Grimaud, Shingo Hido, Sudarshan Karki, Francisco Llamas

Physics & Astronomy Faculty Publications

Current gravitational wave (GW) observatories rely on photon calibrators that use laser radiation pressure to generate displacement fiducials used to calibrate detector output signals. Reducing calibration uncertainty enables optimal extraction of astrophysical information such as source distance and sky position from detected signals. For the ongoing O4 observing run that started on 24 May 2023, the global GW detector network is employing a new calibration scheme with transfer standards calibrated at both the National Institute of Standards and Technology (NIST) and the Physikalisch-Technische Bundesanstalt (PTB). These transfer standards will circulate between the observatories and the metrology institutes to provide laser …

Search For Gravitational-Lensing Signatures In The Full Third Observing Run Of The Ligo–Virgo Network, R. Abbott, H. Abe, F. Acernese, Teviet Creighton, Mario C. Diaz, Francisco Llamas, Soma Mukherjee, Gaukhar Nurbek, Volker Quetschke, Wenhui Wang

Physics & Astronomy Faculty Publications

Gravitational lensing by massive objects along the line of sight to the source causes distortions to gravitational wave (GW) signals; such distortions may reveal information about fundamental physics, cosmology, and astrophysics. In this work, we have extended the search for lensing signatures to all binary black hole events from the third observing run of the LIGO-Virgo network. We search for repeated signals from strong lensing by (1) performing targeted searches for subthreshold signals, (2) calculating the degree of overlap among the intrinsic parameters and sky location of pairs of signals, (3) comparing the similarities of the spectrograms among pairs of …

Strong Edge Burst With Bipolar Non-Hermitian Skin Effect, Cem Yuce, Hamidreza Ramezani

Physics & Astronomy Faculty Publications

We consider a system exhibiting the bipolar non-Hermitian skin effect (NHSE), where bipolar skin states are localized at both edges, and discuss how the topological funneling effect can occur with a single focal point in this system. We explore a topological phase transition from bipolar NHSE to NHSE, which alters the localization characteristics of the eigenstates. After the transition, both the delocalized and bipolar skin states transform into skin states. The non-Hermitian edge burst is a novel and unexpected feature of non-Hermitian quantum dynamics, characterized by substantial particle loss at the boundary of a system. Using the model displaying bipolar …

Simultaneous Chandra And Hst Observations Of The Quiescent Neutron Star Low-Mass X-Ray Binaries In 47 Tucanae, M. Van Den Berg, Liliana E. Rivera Sandoval, C O. Heinke, H. N. Cohn, P. M. Lugger, J. E. Grindlay, P. D. Edmonds, J. Anderson, A. Catuneanu

Physics & Astronomy Faculty Publications

We present simultaneous Chandra X-ray Observatory and Hubble Space Telescope observations of three certain (X5, X7, W37) and two likely (X4, W17) quiescent neutron star low-mass X-ray binaries (qLMXBs) in the globular cluster 47 Tuc. We study these systems in the X-ray, optical, and near-ultraviolet (NUV) using the simultaneous data and additional non-contemporaneous HST data. We have discovered a blue and variable NUV counterpart to W17. We have not securely identified the eclipsing qLMXB W37 in the optical or NUV. Deeper high-resolution imaging is needed to further investigate the faint NUV excess near the centre of the W37 error circle. …

Unbiased Estimation Of Gravitational-Wave Anisotropies From Noisy Data, Nikolaos Kouvatsos, Alexander C. Jenkins, Arianna I. Renzini, Joseph D. Romano, Mairi Sakellariadou

Physics & Astronomy Faculty Publications

One of the most exciting targets of current and future gravitational-wave observations is the angular power spectrum of the astrophysical GW background. This cumulative signal encodes information about the large-scale structure of the Universe, as well as the formation and evolution of compact binaries throughout cosmic time. However, the finite rate of compact binary mergers gives rise to temporal shot noise, which introduces a significant bias in measurements of the angular power spectrum if not explicitly accounted for. Previous work showed that this bias can be removed by cross-correlating GW sky maps constructed from different observing times. However, this …

A Novel Positive-Contrast Magnetic Resonance Imaging Line Marker For High-Dose-Rate (Hdr) Mri-Assisted Radiosurgery (Mars), Li Wang, Yao Ding, Teresa L. Bruno, R. Jason Stafford, Eric Lin, Tharakeswara K. Bathala, Jeremiah W. Sanders, Matthew S. Ning, Jingfei Ma, Karen S. Martirosyan

Physics & Astronomy Faculty Publications

Magnetic resonance imaging (MRI) can facilitate accurate organ delineation and optimal dose distributions in high-dose-rate (HDR) MRI-Assisted Radiosurgery (MARS). Its use for this purpose has been limited by the lack of positive-contrast MRI markers that can clearly delineate the lumen of the HDR applicator and precisely show the path of the HDR source on T1- and T2-weighted MRI sequences. We investigated a novel MRI positive-contrast HDR brachytherapy or interventional radiotherapy line marker, C4:S, consisting of C4 (visible on T1-weighted images) complexed with saline. Longitudinal relaxation time (T1) and transverse relaxation time (T2) for C4:S were measured on a 1.5 T …

Avoiding Pitfalls In Molecular Simulation Of Vapor Sorption: Example Of Propane And Isobutane In Metal–Organic Frameworks For Adsorption Cooling Applications, Filip Formalik, Haoyuan Chen, Randall Q. Snurr

Physics & Astronomy Faculty Publications

This study introduces recommendations for conducting molecular simulations of vapor adsorption, with an emphasis on enhancing the accuracy, reproducibility, and comparability of results. The first aspect we address is consistency in the implementation of some details of typical molecular models, including tail corrections and cutoff distances, due to their significant influence on generated data. We highlight the importance of explicitly calculating the saturation pressures at relevant temperatures using methods such as Gibbs ensemble Monte Carlo simulations and illustrate some pitfalls in extrapolating saturation pressures using this method. For grand canonical Monte Carlo (GCMC) simulations, the input fugacity is usually calculated …

Nanograv 15-Year Gravitational-Wave Background Methods, Aaron D. Johnson, Patrick M. Meyers, Paul T. Baker, Neil J. Cornish, ‪Jeffrey S. Hazboun, Tyson B. Littenberg, Joseph D. Romano, Stephen R. Taylor, Michele Vallisneri

Physics & Astronomy Faculty Publications

Pulsar timing arrays (PTAs) use an array of millisecond pulsars to search for gravitational waves in the nanohertz regime in pulse time of arrival data. This paper presents rigorous tests of PTA methods, examining their consistency across the relevant parameter space. We discuss updates to the 15-year isotropic gravitational-wave background analyses and their corresponding code representations. Descriptions of the internal structure of the flagship algorithms enterprise and ptmcmcsampler are given to facilitate understanding of the PTA likelihood structure, how models are built, and what methods are currently used in sampling the high-dimensional PTA parameter space. We introduce a novel version …

Remnant Polarization And Structural Arrangement In P(Vdf-Trfe) Electrospun Fiber Meshes Affect Osteogenic Differentiation Of Human Mesenchymal Stromal Cells, Bahareh Azimi, Massimiliano Labardi, Mohammad Sajad Sorayani Bafqi, Teresa Macchi, Claudio Ricci, Veronica Carnicelli, Lorenzo Scarpelli, Istiak Hussain, Francesca Matino, Mohammed Uddin

Physics & Astronomy Faculty Publications

Highlights

• The type of solvent had noticeable effects on morphology and piezoelectric properties of P(VDF-TrFE) electrospun fibers.

• Using MEK as a solvent and specific environmental conditions led to the obtainment of surface nanopores.

• Uniaxially aligned fibers exhibited higher β phase and mechanical properties than random ones.

• Randomly oriented fibers had higher remnant piezoelectric properties (Vout, d31 piezoelectric coefficient) than aligned ones.

• Human mesenchymal stem cells cultured on randomly oriented fibers showed an accelerated osteogenic differentiation.

Abstract

Many tissues and cells are influenced by mechano-electric stimulation, thus the application of piezoelectric materials has recently received considerable attention in tissue engineering. …

Search For Gravitational-Wave Transients Associated With Magnetar Bursts In Advanced Ligo And Advanced Virgo Data From The Third Observing Run, R. Abbott, Michael G. Benjamin, Teviet Creighton, Mario C. Diaz, Francisco Llamas, Soma Mukherjee, Gaukhar Nurbek, Volker Quetschke, Wenhui Wang

Physics & Astronomy Faculty Publications

Gravitational waves are expected to be produced from neutron star oscillations associated with magnetar giant flares and short bursts. We present the results of a search for short-duration (milliseconds to seconds) and long-duration (∼100 s) transient gravitational waves from 13 magnetar short bursts observed during Advanced LIGO, Advanced Virgo, and KAGRA's third observation run. These 13 bursts come from two magnetars, SGR 1935+2154 and Swift J1818.0−1607. We also include three other electromagnetic burst events detected by Fermi-GBM which were identified as likely coming from one or more magnetars, but they have no association with a known magnetar. No magnetar giant …

A Search For Intermediate-Mass Black Holes In Compact Stellar Systems Through Optical Emissions From Tidal Disruption Events, Richard T. Pomeroy, Mark A. Norris

Physics & Astronomy Faculty Publications

Intermediate-mass black holes (IMBH) are expected to exist in globular clusters (GCs) and compact stellar systems (CSS) in general, but none have been conclusively detected. Tidal disruption events (TDEs), where a star is tidally disrupted by the gravitational field of a black hole, have been observed to occur around the supermassive black holes (SMBH) found at the centres of galaxies, and should also arise around IMBHs, especially in the dense stellar cores of CSS's. However, to date none have been observed in such environments. Using data from the Zwicky Transient Facility (ZTF) we search for TDEs associated with CSS, but …