A5041315736- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Pulsars and Gravitational Waves Research
- Astrophysics and Cosmic Phenomena
- Astro and Planetary Science
- Solar and Space Plasma Dynamics
- Geophysics and Gravity Measurements
- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- High-pressure geophysics and materials
- Geomagnetism and Paleomagnetism Studies
- Astronomical Observations and Instrumentation
- Calibration and Measurement Techniques
- Atmospheric Ozone and Climate
- Advanced Frequency and Time Standards
- Solid State Laser Technologies
- Statistical and numerical algorithms
- Scientific Research and Discoveries
- Meteorological Phenomena and Simulations
- Radio Astronomy Observations and Technology
- Atomic and Subatomic Physics Research
- Ionosphere and magnetosphere dynamics
- Molecular Spectroscopy and Structure
Northwestern University
2020-2024
Villanova University
2018-2021
Abstract We present the first results of JWST Cycle 1 and 2 observations Sgr A* using NIRCam taken simultaneously at 2.1 4.8 μ m for a total ~48 hr over seven different epochs in 2023 2024. find correlated variability all epochs, continual short-timescale (a few seconds) variability, epoch-to-epoch variable emission implying long-term (~days to months) A*. A highlight this analysis is evidence subminute, horizon-scale time A*, probing inner accretion disk size scales. The power spectra light...
High-resolution Airborne Wide-band Camera (HAWC[Formula: see text]) is the facility far-infrared imager and polarimeter for SOFIA, NASA’s Stratospheric Observatory Infrared Astronomy. It designed to cover portion of infrared spectrum that completely inaccessible ground-based observatories which essential studies astronomical sources with temperatures between tens hundreds degrees Kelvin. Its ability make polarimetric measurements aligned dust grains provides a unique new capability studying...
Abstract We report new polarimetric and photometric maps of the massive star-forming region OMC-1 using HAWC+ instrument on Stratospheric Observatory for Infrared Astronomy. present continuum measurements this at 53, 89, 154, 214 μ m angular resolutions 5″, 8″, 14″, 19″ four bands, respectively. The enable computation improved spectral energy distributions region. find that longer wavelengths, inferred magnetic field configuration matches “hourglass” seen in previous studies, indicating...
Context. The nearby elliptical galaxy M87 contains one of only two supermassive black holes whose emission surrounding the event horizon has been imaged by Event Horizon Telescope (EHT). In 2018, more than dozen multi-wavelength (MWL) facilities (from radio to γ -ray energies) took part in second EHT campaign. Aims. goal this extensive MWL campaign was better understand physics accreting hole M87*, relationship between inflow and inner jets, high-energy particle acceleration. Understanding...
Abstract We present far-infrared polarimetry observations of M82 at 53 and 154 μ m NGC 253 89 m, which were taken with High-resolution Airborne Wideband Camera-plus (HAWC+) in mode on the Stratospheric Observatory for Infrared Astronomy. The polarization clearly shows a magnetic field geometry perpendicular to disk hot dust emission. For combination nuclear region, but closer parallel away from nucleus. fractional (154 m) ranges 7% (3%) off nucleus 0.5% (0.3%) near A simple interpretation...
Far-infrared (FIR) dust polarimetry enables the study of interstellar magnetic fields via tracing polarized emission from grains that are partially aligned with direction field. The advent high quality polarimetric data has permitted use statistical methods to extract both and magnitude In this work, Davis-Chandrasekhar-Fermi technique is used make maps plane-of-sky (POS) component field in Orion Molecular Cloud (OMC-1) by combining polarization at 53, 89, 154 214 \micron\ HAWC+/SOFIA...
We present first results of JWST Cycle 1 and 2 observations Sgr A* using NIRCam taken simultaneously at 2.1 4.8 micron for a total ~48 hours over seven different epochs in 2023 2024. find correlated variability all epochs, continual short-time scale (a few seconds) epoch-to-epoch variable emission implying long-term ( ~days to months) A*. A highlight this analysis is the evidence sub-minute, horizon-scale time A*, probing inner accretion disk size scales. The power spectra light curves each...
Abstract The time-variable emission from the accretion flow of Sgr A*, supermassive black hole at Galactic center, has long been examined in radio-to-millimeter, near-infrared (NIR), and X-ray regimes electromagnetic spectrum. However, until now, sensitivity angular resolution have insufficient crucial mid-infrared (MIR) regime. MIRI instrument on JWST changed that, we report first MIR detection A*. was during a flare that lasted about 40 minutes, duration similar to NIR flares, source's...
We report the first detection of galactic spiral structure by means thermal emission from magnetically aligned dust grains. Our 89 $\mu$m polarimetric imaging NGC 1068 with High-resolution Airborne Wideband Camera/Polarimeter (HAWC+) on NASA's Stratospheric Observatory for Infrared Astronomy (SOFIA) also sheds light magnetic field in vicinity galaxy's inner-bar and active nucleus (AGN). find correlations between vectors other tracers arms, a symmetric polarization pattern as function...
Abstract The dust emission polarization spectrum—how the percentage changes with wavelength—serves as a probe of grain properties in star-forming regions. In this paper, we present 89–214 μ m spectrum measurements obtained from SOFIA/HAWC+ for three clouds: OMC1, M17, and W3. We find that all clouds have an overall decreasing increasing wavelength (i.e., “falling spectrum”). use SOFIA Herschel data to create column density temperature maps each cloud. fit slope at sky position cloud, using...
We study the environment of Sgr A* using spectral and continuum observations with ALMA VLA. Our analysis sub-arcsecond H30alpha, H39alpha, H52alpha H56alpha line emission towards confirm recently published broad peak ~500 km/s~spectrum toward Sgr~A*. also detect at more extreme radial velocities peaking near -2500 4000 km/s, within 0.2''. then present band radio images multiple frequencies on scales from arcseconds to arcminutes. A number elongated structures lie parallel Galactic plane,...
ABSTRACT We report 235 GHz linear and circular polarization (LP CP) detections of Sgr A* at levels $\sim 10\,{{\rm per\, cent}}$ -1\,{{\rm cent}}$, respectively, using ALMA. describe the first full-Stokes modelling an observed submillimetre flare with adiabatically expanding synchrotron hotspot a polarized radiative transfer prescription. Augmented simple model for quiescent emission, we jointly characterize properties both variable components by simultaneously fitting all four Stokes...
ABSTRACT The Snake is a remarkable Galactic Centre radio filament with morphology characterized by two kinks along its ∼20 arcmin extent. major and minor are located where the most distorted from linear magnetized structure running perpendicular to plane. We present Chandra, VLA, MeerKAT data report detection of an X-ray source at location kink. High-resolution images kink reveal compact steep spectrum spectral index α ∼ −2.7 surrounded extended emission. luminosity consistent pulsar. also...
We present and analyze ALMA submillimeter observations from a multi-wavelength campaign of Sgr A* during 18 July 2019. In addition to the submillimeter, we utilize concurrent mid-IR (Spitzer) X-ray (Chandra) observations. The emission lags less than $\delta t\approx30$ minutes behind data. However, entire flare was not observed, raising possibility that time delay is consequence incomplete sampling light curve. decay consistent with synchrotron cooling. Therefore, these data adopting an...
Abstract The linear polarization of thermal dust emission provides a powerful tool to probe interstellar and circumstellar magnetic fields, because aspherical grains tend align themselves with field lines. While the Radiative Alignment Torque (RAT) mechanism theoretical framework for this phenomenon, some aspects alignment still need be quantitatively tested. One such aspect is possibility that reference direction changes from (“ B -RAT”) radiation k-vector k in areas strong fields. We...
Abstract We report on the final two days of a multiwavelength campaign Sgr A* observing in radio, submillimeter, infrared (IR), and X-ray bands 2019 July. was remarkably active, showing multiple flaring events across electromagnetic spectrum. detect transient ∼35 minute periodicity feature Spitzer light curves July 21. Time-delayed emission detected Atacama Large Millimeter/submillimeter Array curves, suggesting hotspot within accretion flow stable orbit. On same night, we observe decreased...
We report on polarimetric maps made with HAWC+/SOFIA toward ρ Oph A, the densest portion of Ophiuchi molecular complex. employed HAWC+ bands C (89 μm) and D (154 μm). The slope polarization spectrum was investigated by defining quantity , where pC pD represent degrees in D, respectively. find a clear correlation between hydrogen column density across cloud. A positive ( > 1) dominates lower-density well-illuminated portions cloud, which are heated high-mass star S1, whereas transition to...
Abstract Complex organic molecules (COMs) are believed to form in the ice mantle of dust grains and released gas by thermal sublimation when grain mantles heated temperatures <?CDATA ${T}_{{\rm{d}}}\gtrsim 100\,{\rm{K}}$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>T</mml:mi> </mml:mrow> <mml:mi mathvariant="normal">d</mml:mi> </mml:msub> <mml:mo>≳</mml:mo> <mml:mn>100</mml:mn> <mml:mspace width="0.25em" />...
ABSTRACT We investigate the nature of a Galactic Centre source, G0.17+0.15, lying along northern extension radio arc near l ∼ 0.2°. G0.17+0.15 is an H ii region located towards eastern edge bubble, embedded within highly polarized lobe where number filaments appear to cross through region. report detection hydrogen and helium recombination lines with radial velocity exceeding 140 km s−1 based on Green Bank Telescope Very Large Array observations. The morphology aided by kinematics, spectral...
ABSTRACT The detection of an X-ray filament associated with the radio G0.173–0.42 adds to four other non-thermal filaments counterparts, amongst more than 100 elongated structures that have been identified as synchrotron-emitting in inner couple degrees Galactic centre. synchrotron mechanism has also proposed explain emission from filaments. However, origin and acceleration sites energetic particles produce X-rays remain mysterious. Using MeerKAT, VLA, Chandra, WISE, Spitzer, we present...
We report the detection and analysis of a radio flare observed on 17 April 2014 from Sgr A* at $9$ GHz using VLA in its A-array configuration. This is first reported simultaneous observation across $16$ frequency windows between $8$ $10$ GHz. cross correlate lowest highest spectral centered $8.0$ $9.9$ GHz, respectively, find light curve lagging $18.37^{+2.17}_{-2.18}$ minutes behind curve. time lag found A*'s narrow bandwidth. separate quiescent flaring components via flux offsets each...
SOFIA HAWC+ polarimetry at $154~\micron$ is reported for the face-on galaxy M51 and edge-on NGC 891. For M51, polarization vectors generally follow spiral pattern defined by molecular gas distribution, far-infrared (FIR) intensity contours, other tracers of star formation. The fractional much lower in FIR-bright central regions than outer regions, we rule out loss grain alignment variations magnetic field strength as causes. When compared with existing synchrotron observations, which sample...
The Snake is a remarkable Galactic center radio filament with morphology characterized by two kinks along its $\sim 20'$ extent. major and minor are located where the most distorted from linear magnetized structure running perpendicular to plane. We present {\em Chandra}, VLA, MeerKAT data report detection of an X-ray source at location kink. High-resolution images kink reveal compact steep spectrum spectral index alpha ~ -2.7 surrounded extended emission. luminosity consistent pulsar. also...
We investigate the nature of a Galactic center source, G0.17+0.15, lying along northern extension Radio Arc near l~0.2deg. G0.17+0.15 is an HII region located toward eastern edge radio bubble, embedded within highly polarized Lobe where number filaments appear to cross through region. report detection hydrogen and helium recombination lines with radial velocity exceeding 140 km/s based on GBT VLA observations. The morphology aided by kinematics, spectral index characteristics, suggests...