A5059328822- Astrophysical Phenomena and Observations
- Astrophysics and Cosmic Phenomena
- Pulsars and Gravitational Waves Research
- Gamma-ray bursts and supernovae
- Mechanics and Biomechanics Studies
- Astronomical Observations and Instrumentation
- Radio Astronomy Observations and Technology
- Particle Accelerators and Free-Electron Lasers
- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- High-pressure geophysics and materials
- Advanced X-ray Imaging Techniques
- Adaptive optics and wavefront sensing
- Astrophysics and Star Formation Studies
- Galaxies: Formation, Evolution, Phenomena
- Geophysics and Sensor Technology
- Computational Physics and Python Applications
- Ionosphere and magnetosphere dynamics
- Neutrino Physics Research
- Particle Detector Development and Performance
- Particle physics theoretical and experimental studies
- Geophysics and Gravity Measurements
- Structural Health Monitoring Techniques
- GNSS positioning and interference
- Solar and Space Plasma Dynamics
University of Lethbridge
2023-2025
Texas Tech University
2022-2024
East Asian Observatory
2018-2024
Albert Einstein College of Medicine
2022-2023
University of Alberta
2015-2020
A heavy black hole in an x-ray binary If a interacts with companion star, the system emits x-rays and can form radio jet. The masses of holes these binaries are all lower than those detected using gravitational waves, challenging models formation from massive stars. Miller-Jones et al. used astrometry to refine distance Cygnus X-1, well-studied binary. They found larger previous estimates, raising mass 21 solar masses. results challenge wind loss rates implemented stellar evolution models....
The Event Horizon Telescope (EHT) observed the compact radio source, Sagittarius A* (Sgr A*), in Galactic Center on 2017 April 5-11 1.3 millimeter wavelength band. At same time, interferometric array data from Atacama Large Millimeter/submillimeter Array and Submillimeter were collected, providing Sgr light curves simultaneous with EHT observations. These sets, complementing very-long-baseline interferometry, are characterized by a cadence signal-to-noise ratio previously unattainable for at...
Using the Very Long Baseline Array and European Interferometry Network we have made a precise measurement of radio parallax black hole X-ray binary MAXI\,J1820+070, providing model-independent distance to source. Our ($0.348\pm0.033$) mas for MAXI J1820+070 translates ($2.96\pm0.33$) kpc. This implies that source reached ($15\pm3)\%$ Eddington luminosity at peak its outburst. Further, use this refine previous estimates jet inclination angle, velocity mass in be ($63\pm3)^{\circ}$,...
Abstract Quasi-periodic eruptions (QPEs) are luminous X-ray outbursts recurring on hour timescales, observed from the nuclei of a growing handful nearby low-mass galaxies. Their physical origin is still debated, and usually modeled as (a) accretion disk instabilities or (b) interaction supermassive black hole (SMBH) with lower mass companion in an extreme mass-ratio inspiral (EMRI). EMRI models can be tested several predictions related to short- long-term behavior QPEs. In this study, we...
Abstract Black hole (BH) X-ray binaries (XRBs) are ideal targets to study the connection between accretion inflow and jet outflow. Here we present quasi-simultaneous, multiwavelength observations of Galactic BH system MAXI J1820+070, throughout its 2018–2019 outburst. Our data set includes coverage from radio through bands 17 different instruments/telescopes, encompasses 19 epochs over a 7 month period, resulting in one most well-sampled sets XRB outburst date. With our data, compile model...
We present simultaneous radio through sub-mm observations of the black hole X-ray binary (BHXB) V404 Cygni during most active phase its June 2015 outburst. Our $4$ hour long set overlapping with Very Large Array, Sub-millimeter and James Clerk Maxwell Telescope (SCUBA-2), covers 8 different frequency bands (including first detection a BHXB jet at $666 \,{\rm GHz}/450\mu m$), providing an unprecedented multi-frequency view extraordinary flaring activity seen this period In particular, we...
ABSTRACT We present the radio and X-ray monitoring campaign of 2019/2020 outburst MAXI J1348–630, a new black hole binary (BH XRB) discovered in 2019 January. observed J1348–630 for ∼14 months band with MeerKAT Australia Telescope Compact Array, X-rays Swift/XRT. Throughout outburst, we detected tracked evolution compact transient jets. Following main system underwent at least four hard-state-only re-flares, during which jets were again detected. For major rise, quenching reactivation jets,...
Abstract The Submillimetre Common User Bolometer Array 2 (SCUBA-2) is the James Clerk Maxwell Telescope’s continuum imager, operating simultaneously at 450 and 850 μ m. SCUBA-2 was commissioned in 2009–2011, since that time, regular observations of point-like standard sources have been performed whenever instrument use. Expanding calibrator observation sample by an order magnitude compared to previous work, this paper we derive updated opacity relations each wavelength for a new atmospheric...
ABSTRACT We present multiwavelength fast timing observations of the black hole X-ray binary MAXI J1820+070 (ASASSN-18ey), taken with Karl G. Jansky Very Large Array (VLA), Atacama Millimeter/Sub-Millimeter (ALMA), Telescope (VLT), New Technology (NTT), Neutron Star Interior Composition Explorer (NICER), and XMM–Newton. Our data set simultaneously samples 10 different electromagnetic bands (radio – X-ray) over a 7-h period during hard state 2018–2019 outburst. The emission we observe is...
Abstract Multiwavelength polarimetry and radio observations of Swift J1727.8–1613 at the beginning its recent 2023 outburst suggested presence a bright compact jet aligned in north–south direction, which could not be confirmed without high-angular-resolution images. Using Very Long Baseline Array Array, we imaged during hard/hard-intermediate state, revealing core large, two-sided, asymmetrical, resolved jet. The extends position angle −0.60° ± 0.07° east north. At 8.4 GHz, entire structure...
MAXI J1836-194 is a Galactic black hole candidate X-ray binary that was discovered in 2011 when it went into outburst. In this paper, we present the full radio monitoring of system during its `failed' outburst, which source did not complete set state changes, only transitioning as far hard intermediate state. Observations with Karl G. Jansky Very Large Array (VLA) and Australia Telescope Compact (ATCA) show jet properties changed significantly The VLA observations detected linearly polarised...
We present simultaneous multiband radio and X-ray observations of the black hole binary Cygnus X-1, taken with Karl G. Jansky Very Large Array Nuclear Spectroscopic Telescope Array. With these data, we detect clear flux variability consistent emission from a variable compact jet. To probe how signal propagates down jet flow, perform detailed timing analyses our data. find that shows no significant power at Fourier frequencies f ≳ 0.03 Hz (below ∼30 s time-scales), higher frequency bands...
ABSTRACT During a 2018 outburst, the black hole X-ray binary MAXI J1820 + 070 was comprehensively monitored at multiple wavelengths as it underwent hard to soft state transition. this transition, rapid evolution in timing properties and short-lived radio flare were observed, both of which linked launching bi-polar, long-lived relativistic ejecta. We provide detailed analysis two Very Long Baseline Array observations, using time binning new dynamic phase centre tracking technique mitigate...
Abstract We study the jet in hard state of accreting black hole (BH) binary MAXI J1820+070. From available radio-to-optical spectral and variability data, we put strong constraints on parameters. find while it is not possible to uniquely determine Lorentz factor from properties alone, can estimate opening angle (≈1.°5 ± 1°), distance at which starts emitting synchrotron radiation (∼3 × 10 cm), magnetic field strength there (∼10 4 G), with relatively low uncertainty, as they depend weakly...
ABSTRACT We present results from six epochs of quasi-simultaneous radio, (sub-)millimetre, infrared, optical, and X-ray observations the black hole binary MAXI J1535−571. These show that as source transitioned through hard–intermediate state towards soft–intermediate state, jet underwent dramatic rapid changes. observed frequency spectral break, which corresponds to most compact region in where particle acceleration begins (higher frequencies indicate closer hole), evolves infrared band into...
Cygnus X--1 is the first Galactic source confirmed to host an accreting black hole. It has been detected across entire electromagnetic spectrum from radio GeV $\gamma$-rays. The source's through mid-infrared radiation thought originate relativistic jets. observed high degree of linear polarisation in MeV X-rays suggests that jets dominate this regime as well, whereas a hot accretion flow dominates soft X-ray band. origin non-thermal emission still debated, with both leptonic and hadronic...
Black hole low mass X-ray binaries (BH LMXBs) can launch powerful outflows in the form of discrete ejecta. Observing entire trajectory these ejecta allows us to model their motion with great accuracy, and this is essential for measuring physical properties. In particular, observing final deceleration phase, often poorly sampled, fundamental obtain a reliable estimate jet's energy. During its 2019/2020 outburst, BH LMXB MAXI J1348$-$630 launched single-sided radio-emitting jet that was...
We present the results of VLA, ATCA, and Swift XRT observations 2015 outburst transient neutron star X-ray binary (NSXB), EXO 1745$-$248, located in globular cluster Terzan 5. Combining (near-) simultaneous radio measurements we measure a correlation between luminosities $L_R\propto L_X^\beta$ with $\beta=1.68^{+0.10}_{-0.09}$, linking accretion flow (probed by luminosity) compact jet luminosity). While such relationship has been studied multiple black hole binaries (BHXBs), this work marks...
Very faint X-ray transients (VFXTs) are with peak luminosities ($L_X$) of $L_X\lesssim10^{36}$ erg/s, which not well-understood. We carried out a survey 16 square degrees the Galactic Bulge Swift Observatory, using short (60 s) exposures, and returning every 2 weeks for 19 epochs in 2017-18 (with gap from November 2017 to February 2018, when was sun-constraint). Our main goal detect study VFXT behaviour across various classes sources. In this work, we explain observing strategy survey,...
Abstract We present mid-infrared (MIR) spectral-timing measurements of the prototypical Galactic microquasar GRS 1915+105. The source was observed with Mid-Infrared Instrument (MIRI) onboard JWST in June 2023 at a MIR luminosity LMIR ≈ 1036 erg s−1 exceeding past IR levels by about factor 10. In contrast, X-ray flux is much fainter than historical average, source’s now–persistent ‘obscured’ state. MIRI low-resolution spectrum shows plethora emission lines, strongest which are consistent...