Authors: Gerard van Belle (Lowell Observatory), Michelle Creech-Eakman (NMT)

Abstract: One of the most influential prototype optical interferometers was the Palomar Testbed Interferometer (PTI), which was located on Palomar Mountain next to the historic 5-m Hale telescope in the 1990s and 2000s. PTI was a groundbreaking technology demonstrator, but produced highly regarded science accomplishments in its own regard as well. I will present a brief accounting of the impressive technology of PTI, its past science results, some new results, and prospects for a continuing legacy of science investigations from its data archive.

Authors: David F. Buscher (University of Cambridge), Michelle Creach-Eakman (NMT), Van Romero (NMT), Chris A. Haniff (University of Cambridge), John S. Young (University of Cambridge)

Abstract: We discuss the science remit, design and present status of the Magdalena Ridge Observatory Interferometer (MROI). The MROI is a collaboration between New Mexico Tech and the University of Cambridge to build an optical/infrared aperture synthesis array on a high-altitude site near Socorro, NM. The MROI has been designed to deliver a combination of angular resolution, imaging speed and access to faint sources which is unmatched by any existing interferometer. The second telescope of the array is being installed on the Ridge and we are aiming for first fringes this year.

Talk slides

Authors: Eileen V. Ryan (Director, 2.4m Telescope; NMT) & William H. Ryan (MRO, NMT)

Abstract: The NASA's DART Spacecraft successfully kinetically impacted the small moon of the binary near-Earth asteroid pair Didymos and Dimorphos on September 26, 2022. This was the first test that NASA's Planetary Defense Office has conducted to determine whether we have the technology to deflect dangerous asteroids from hitting the Earth in the future. The Magdalena Ridge Observatory's (MRO) 2.4-meter Telescope is one of only 4 contracted (funded) observatories tasked with helping to determine the DART mission's major deliverable a quantitative measurement via ground-based telescopic observations of how much the moonlet Dimorphos' orbit around its parent body Didymos has changed post-impact. MRO researchers Drs. Bill and Eileen Ryan are Investigative Team members on this mission, and will report on the ongoing data acquisition and the implications for planetary defense.

Talk slides (pdf) Talk slides (ppt)

Authors: Zachariah Goodrich (NMT), Alex Canales (NMT), Daniel Hojnowski (NMT), Susanna Lanucara (NMT), Michael Rodriguez (NMT), Robert Volkmann (NMT), Josiah Smith (NMT)

Abstract: The Wide field Infrared Kuiper belt and Exoplanet Explorer telescope (WIKEE) is a telescope system designed to be run in clusters to cover a greater area of sky in one session than possible with a single telescope. With visible light and infrared capabilities, these 0.7 meter telescopes are designed to be remotely operated and have the capabilities to find comets, asteroids, conduct surveys on red and brown dwarf stars, and assist in the exploration of exoplanets in the night sky.

During the beginning phase of the WIKEE project a small proof of concept telescope was designed and is currently under construction. The goal of this step is to provide insight into the performance of a new style of direct drive stepper motor system and to explore the atmospheric limitations of wavelengths from 0.7-2.1 µm at possible observing sites. Supplying the groundwork for communication between telescopes in a cluster is what the small 90mm prototypes will excel in. Follow up observations in astronomy are as important as the initial discovery. The WIKEE system is designed to be a low cost expendable secondary resource. We believe that having a “hive” telescope could provide a sub 1-meter system with significant relevance in groundbreaking astronomical observations.

Talk slides

Authors: Walter Brisken (NRAO), Patrick Taylor (NRAO), Flora Paganelli (NRAO), Tony Beasley (NRAO), Steven Wilkinson (Raytheon Technologies), Bishara Shamee (Raytheon Technologies), Aaron Wallace (Raytheon Technologies)

Abstract: he National Radio Astronomy Observatory and Green Bank Observatory are partnering with Raytheon Technologies to explore options for a high-power multi-static planetary radar system. During the pandemic, a 700W prototype radar system was constructed and installed on the GBT and used with VLBA antennas as receiving elements, spectacularly proving the concept by imaging the moon and detecting a near-earth asteroid. The parties are currently developing a concept for a 500 kW radar system centered at 13.7 GHz.

Talk slides

Authors: The COSMIC Team (SETI Institute)

Abstract: The search for complex life via technosignatures, observational manifestations of technology, aims to detect or constrain the prevalence of technologically advanced life in the Universe (also known as the search for extraterrestrial intelligence or SETI). COSMIC - the Commensal Open-source Multimode Interferometer Cluster - is a new instrument for the VLA under development by the SETI Institute. COSMIC receives a copy of the digitized data stream from each VLA antenna and searches for narrow-band (~Hz-level) frequency-drifting signals from targets of interest, generally nearby stars. This is done in parallel with most standard VLA scientific observations, including the ongoing VLA Sky Survey (VLASS). Via this commensal approach, we expect COSMIC to observe ~millions of stellar systems per year, roughly three orders of magnitude more stars than searched in previous SETI efforts. COSMIC is currently undergoing commissioning tests and beginning early science observations. I will present the motivations, design, and initial results of the project, as well as potential future upgrades over the coming years.

Talk slides

Authors: Bryan Butler (NRAO), Eric Murphy (NRAO), Rob Selina (NRAO), Tony Beasley (NRAO)

Abstract: Building on the remarkable success of the VLA, VLBA, and ALMA, NRAO is planning a large collecting area interferometer which will replace the VLA and VLBA - the next generation Very Large Array (ngVLA). For many of the same reasons that the VLA was constructed where it was (fraction of sky visible, quality of site, accessibility, etc.), the core and bulk of the collecting area of the ngVLA will be on the Plains of San Agustin, near where the center of the current VLA is. The ngVLA will have more than 10 times the sensitivity and spatial resolution of the VLA and ALMA, operating at frequencies from 1.2-116 GHz. The ngVLA will be optimized for observations at wavelengths between those of ALMA at mm-submm wavelengths, and the future SKA-1 at dm-m wavelengths, to be complementary to those instruments. The ngVLA will be transformative, with exquisite sensitivity to thermal line and continuum emission down to milliarcsecond resolution. The science goals are broad (a science book with more than 90 chapters and 285 unique authors has been written), but focus on: formation of planetary systems on terrestrial planet scales, including astrochemistry; characterization of galaxy structure and evolution; using pulsars in the Galactic center to test fundamental theories of gravity; and understanding the formation and evolution of stellar and supermassive black holes in the era of multi-messenger astronomy.

Authors: W. Thomas Vestrand (LANL), Yancey H. Sechrest (LANL), Robert J. Hill Jr. (LANL), Michael J. Giblin (LANL), David M. Palmer (LANL), Lucas P. Parker (LANL), Przemek R. Wozniak (LANL)

Abstract: The recent discovery of sub-second, bright, optical flashes that display a point-like nature in wide- field sky monitoring images has generated questions about their origin. Are they all generated by non-astrophysical sources? Or are some of the sub-second flashes of astrophysical origin? At Los Alamos National Laboratory, we are constructing a stereoscopic ranging system that employs high-speed CMOS cameras on identical, wide-field, telescopes deployed at two different, dark, high-altitude, observatory sites. One telescope is located near the Los Alamos Neutron Science Center (LANSCE) at an elevation of 7,320 ft in Los Alamos, New Mexico. The other telescope is located at the Fenton Hill Observatory site in the Jemez mountains at an elevation of 8,720 ft. The baseline is almost due east-west; with an east-west length of 37.98 km and a north-south length of 1.33 km. This baseline combined with the resolving power of the telescopes will allow us to measure the parallax of ultra-fast optical flashes out to a range of 10x the distance of the moon. This, in turn, we will allow us to identify, on a flash-by-flash basis, foreground noise and conduct a search for ultra-fast, astrophysical, optical flashes.

Authors: Akshatha K Vydula (ASU), Danny Jacobs (ASU), Judd Bowman (ASU)

Abstract: The accuracy of the antenna beam model is a limiting factor to many radio astronomy applications. This is particularly true for the Long Wavelength Array where uncertainty in the wide field impacts searches for exoplanets and high-redshift 21cm spectroscopy. One way to measure the beam of a fixed dipole array is by cross-correlation with a well calibrated dish. At OVRO, the plan is to use the nearby 40m dish with a custom LWA feed cross-correlating with LWA antennas. As a precursor test, we have used the eLWA system in New Mexico (VLA in B-configuration, co-located LWA-1 and LWA-SV stations). We observed pulsars which can help reduce beam errors associated with incomplete source catalogs and uncertainties in source fluxes. The difference between the on-pulse and off-pulse periods corresponds to a stable, reasonably known flux of the pulse, providing an absolute flux reference that is not contaminated by diffuse background sky emission. We were able to verify the system equivalent flux density (SEFD) of LWA-1 to be 4680Jy at 75MHz by detecting the pulsar B1133+16 with an SNR of 9dB using both eLWA binning correlator and PRESTO. This is an on-going project and I will present the latest progress. We aim to use this method to measure the SEFD of VLA, which is poorly known at 4-meter wavelengths. We will then use cross-correlations of the pulsar signal between the two telescopes to measure the LWA-1 average antenna beam response along the path of the pulsar.

Talk slides

Authors: Craig Taylor (UNM), Gregory Taylor (UNM), Jayce Dowell (UNM)

Abstract: Wide-field imaging using the E-Field Parallel Imaging Correlator (EPIC) architecture for interferometric arrays has been shown to be an effective method for high-cadence, all-sky observations (Thyagarajan et al. 2017). This parameter space in high-resolution imaging arrays was previously inaccessible with traditional correlation algorithms due to the high computation load associated with gridding or FFT-based methods (Kent et al. 2019). The EPIC formalism was demonstrated using the Long Wavelength Array (LWA) in Kent (2019) and motivates further testing and comparison of this electric field-based direct imaging method with traditional correlated imaging. We present an observation of Crab Pulsar using standard FX-correlated observations with the LWA Sevilleta Station (LWA-SV) and its commensal EPIC imaging mode. Comparing these results provides essential insight on how the two observing modes function, and how we can exploit the strengths of both instruments in future LWA research of Pulsars, Fast Radio Bursts, and other fast time-domain transient phenomena.

Talk slides

Authors: Brian Kirk (NMT, NRAO)

Abstract: Current calibration and image processing is done with hard coded scripts, called ‘recipes’, for bulk data reduction at the observatory. Data analysts are required to manually fine tune these recipes for quality assurance and to error-check any mistakes. This human-based optimization and error-checking is a bottleneck to automation throughput. Our research involves moving away from hard coded scripts to a system capable of deciding the best action to take based on input data. Our work includes estimating a numerical value for actions in a given context and automating the decision process. We will present results from a prototype that addresses a very controlled situation involving averaging choices prior to calibration.

Authors: Presented on behalf of the VLASS Team and the VLASS Survey Science Group.

Abstract: NRAO has recently begun observing the 3rd Epoch of the VLA Sky Survey (VLASS). VLASS is a synoptic, wide-field radio sky survey with a unique combination of high angular resolution (approx 2.5arcsec), sensitiv ty (a 1-sigma goal of 70 microJy/beam in the co-added data), full linear Stokes polarimetry, time domain coverage, and wide bandwidth (2-4 GHz). By the time of its completion, VLASS will have used approximately 5500 hr of time on the Karl G. Jansky Very Large Array to cover the whole sky visible to the VLA (decl. > -40deg), a total of 33,885 square degrees. Observations are being performed in three epochs over 7 years (from 2017 September to 2024) to support the discovery of variable and transient radio sources. By utilizing the VLA’s "On-The-Fly" interferometry mode, the observing overheads are much reduced compared to a conventional pointed survey. In this presentation, I will give an overview to VLASS including the data products, quality assurance procedures, new science highlights, and an update on the current survey status.

Authors: Eli Pattie (TTU) & Tom Maccarone (TTU)

Abstract: e present the results of a 3 square degree radio survey in the Galactic Bulge at 1-2GHz, with sensitivity of ~0.1mJy and resolution of ~1.1 arcsec. We find 1605 radio sources, and calculate spectral indices within our 1-2GHz observation. We find ~100 steep spectrum point sources that are viable pulsar candidates, suggestive evidence that there are many undiscovered pulsars in this region of the Galaxy. We matched our catalog to the Chandra Galactic Bulge Survey and other public catalogs. Some of the radio matched sources of interest are: an X-ray source that was classified as an accreting white dwarf; a potential transitional millisecond pulsar candidate; a radio counterpart to a YSO-type infrared outburst object; possible new planetary nebulae based on appearance and MIPSGAL counterparts; and interesting AGN, such as X-shaped and steep spectrum. We also find sources that appear to be transient based on comparisons to VLASS and RACS.

Talk slides

Authors: Asif Abbas (NMSU), Christopher W. Churchill (NMSU), Glenn G. Kacprzak (Swinburne University), Susanna Guatelli (University of Wollongong), Christopher Lidman (ANU, Australia), Sabine Bellstedt (ICRAR, Australia)

Abstract: We present the first Southern Hemisphere survey of Mg II QSO absorption line systems in 951 QSO spectra from the Australian Dark Energy Survey (OzDES-DR2). We detected 337 systems spanning the redshift range 0.33 < z < 2.19. The spectra are 50% complete to W_r(2796) = 0.31 Angstrom. We find that the Mg II equivalent width distribution is consistent with Northern Hemisphere results from the Sloan Digitial Sky Survey (SDSS, e.g., Nestor+, 2005; Zhu & Menard 2013), and is well fit by an exponential, n(W_r) = (N*/W*)exp(−W_r/W*), with W* = 0.60 +/- 0.06 Angstrom and N* = 1.82 +/- 0.28. Though it is well established that the evolution in the cosmic number density of Mg II systems traces the global star formation history of the universe, historically, evolution in the mass density of Mg II systems, Ω_MgII, has eluded a robust quantification. Here, we present a novel approach to computing the Ω_MgII, from low resolution spectra. The method holds promise for precision measurements of the cosmic mass density of metal-line QSO absorbers, such those tracing silicon, carbon, and oxygen, observed in ~106 QSO spectra from SDSS.

Talk slides

Authors: Rajorshi Bhattacharya (UNM) & Ylva Pihlstrom (UNM)

Abstract: The BAaDE project has delivered line-of-sight velocities to more than 10,000 AGB stars in the Milky Way. To incorporate these velocities into dynamical models, and to distinguish different AGB populations, distance estimates are crucial to determine 3D positions as well as mass loss rates and luminosities. For AGB stars in particular, Gaia parallaxes have been shown to be prone to large error. Therefore, we investigate an alternative method to estimate the distances for the AGB stars, utilizing the rich auxiliary infrared data sets available for these infrared-bright targets. The method is based on the assumption that stars with intrinsically similar properties (metallicity, initial mass, etc) produce similar spectral energy distributions (SEDs) with similar luminosity. Through distance-calibrated template SEDs distances are estimated. We here discuss the results for AGB stars belonging to the BAaDE survey sample using templates with distances calibrated with VLBI parallaxes. As VLBI parallaxes are only known for a handful of sources, the resulting templates only cover a small subset of the BAaDE sample. Additional methods to derive suitable templates will therefore also be required.

Talk slides

Authors: Ryan Boyden (University of Arizona) & Josh Eisner (University of Arizona)

Abstract: Protoplanetary disks are the birthplaces of planetary systems, and obtaining a complete picture of how planets form hinges on an understanding of how disks evolve throughout the Galaxy. The Atacama Large Millimeter Array (ALMA) and Karl G. Jansky Very Large Array (VLA) provide the sensitivity and resolution needed to detect large samples of protoplanetary disks in rich clusters, the most common sites of star formation in our Galaxy. In this talk, I will present the analysis of deep, high-resolution ALMA CO(3-2) and HCO+(4-3) observations covering a large sample of disks in the Orion Nebula Cluster (ONC). I first introduce the sample of disks that are detected in the observations, and outline a novel procedure that utilizes thermochemical modeling to constrain the disk masses, gas-to-dust ratios, and central stellar masses of the detected sources. I find that the ONC disks are massive and compact, with typical radii <100 AU, gas masses >1 Jupiter mass, and gas-to-dust ratios >=100. The ISM-like gas-to-dust ratios derived from thermochemical modeling suggest that compact disks in the ONC are less prone to gas-phase CO depletion than the massive, extended disks that are commonly found in lower-mass star-forming regions. The presence of massive gas disks indicates that a subset of disks in the ONC still have plenty of material to form giant planets. Finally, I will discuss my recent work with the VLA to measure the free-free emission spectra and complete the census of "proplyds" towards young stellar objects in the NGC 1977 and NGC 2024 clusters.

Talk slides (pdf) Talk slides (key)

Authors: Kedron Silsbee (University of Texas at El Paso), Vitaly Akimkin (Institute of Astronomy, Russian Academy of Sciences), Alexei V. Ivlev (Max Planck Institute for Extraterrestrial Physics), Leonardo Testi (ESO), Munan Gong (Max Planck Institute for Extraterrestrial Physics), Paola Caselli (Max Planck Institute for Extraterrestrial Physics)

Abstract: Recent observations of millimeter emission have been interpreted as indicating the presence of mm-sized dust grains at scales of 500 AU in the envelopes of class 0 and 1 protostars. This has been a puzzle, as numerical simulations of the growth of dust grains have not been able to reach even close to this size in similar environments. However, it is has been difficult to make a decisive statement from these simulations due to the large parameter space. I present an analytic model for the growth of dust grains, including the effect of grain porosity. This model is tested against numerical simulations and shown to be accurate. From this model, we place a robust limit on the maximum grain size that is sensitive only to the product of envelope lifetime, density, and the threshold velocity for collisional fragmentation. This limit cannot be overcome by changing the properties of the turbulence, or the fractal dimension of the growing grains. I will also briefly discuss a few other possibilities to explain the low observed spectral indices of millimeter emission without invoking large dust grains.

Talk slides (key)

Authors: Dylan Gayer (UNM) & Pedro P.B. Beaklini (NRAO)

Abstract: Since the beginning of ALMA’s operation, our understanding of the birth of massive stars has broadened. Many new projects and surveys have been performed that focus on the study of infrared dark clouds, identified as IRDC. These sources are composed of many cores of dust condensations and low-temperature, dense gas. We have explored the ALMA and VLA data archives to search for molecular line emission and protostellar clumps in the continuum maps. We have found two sources, IRDC-B2 and IRDC-C9, that show molecular line emissions identified as sulfur-bearing molecules OCS and 13CS, and other complex organic molecules like methanol. Both sources show evidence of hosting a protostar, but there is still missing information to characterize the sources. Further research has been proposed to the SMA to investigate other transitions of methanol, which could show outflow features and confirm the identity of these sources as massive protostars.

Talk slides

Authors: Samantha Scibelli (University of Arizona), Yancy Shirley (University of Arizona), Anika Schmiedeke (GBO), Brian Svoboda (NRAO), Ayushi Singh (University of Toronto), James Lilly (University of Wyoming), Paola Caselli (Max Plack Inst. for Extraterrestrial Physics)

Abstract: Detailed studies of starless cores allow us to investigate the initial physical and chemical conditions prior to stellar birth. The best way to probe the physical structure of starless cores is through thermal emission of dust grains, while molecular line emission is best suited to probe the cold (10 K) core’s chemistry. 3D radiative transfer modeling results will be presented for the 14 starless cores that reside in the B10 region of Taurus Molecular Cloud - a young and less evolved region with prevalent complex organic molecule (COM) chemistry whose evolution has not been significantly disturbed by feedback from star formation. High resolution 1.2 mm and 2.0 mm dust continuum maps (at 12 arcsec and 18 arcsec, respectively) of B10 were taken with the NIKA2 instrument on the IRAM 30m telescope. A grid of over one million models constrained each cores’ central density, density slope, aspect ratio, opacity, and interstellar radiation field strength. From the modeled 3D density structures, a self-consistent virial analysis was done to assess each core’s stability and evolutionary state. Ignoring contributions from magnetic fields, we find most (64%) of the cores are either in virial equilibrium or are bound by gravity and external pressure. Additional constraints on the dynamical evolution of these starless cores are set through a CO-depletion analysis, made possible by complementary high resolution (7 arcsec) Green Bank 100m Telescope (GBT) ARGUS observations of C18O (1-0). For the first time, we have evaluated the physical properties and evolutionary states of B10’s 14 COM-rich starless cores.

Talk slides

Authors: Tatiana M. Rodriguez (NMT), Emmanuel Momjian (NRAO), Peter Hofner (NMT, NRAO), Anuj P. Sarma (DePaul University), Esteban D. Araya (Western Illinois University, NMT), Viviana Rosero (NRAO)

Abstract: A key aspect in the earliest evolutionary phase of high-mass (M > 8 Msun) star formation is the presence of a jet/outflow system. To study its role, we have carried out high resolution (0.1”) VLA K-band (18-26.5 GHz) observations toward IRAS 19035+0641 A, identified as a high-mass protostellar jet based on previous cm continuum data. Our observations resolve the continuum emission into two peaks aligned in a NE-SW direction, and our results confirm the jet nature of the emission. Furthermore, we detected several 22.2 GHz H2O maser spots aligned in a direction consistent with the jet axis. Zeeman splitting was detected in the strongest maser spot and the derived line of sight magnetic field (B_los) was used to further characterize the young stellar object. In this talk, I will present our results and discuss the implications of our findings.

Talk slides

Authors: Chenoa Tremblay (SETI) & Lorant Sjouwerman (NRAO)

Abstract: The study of the transverse motion of M31 (the Andromeda Galaxy) with respect to the Milky Way is important in understanding the history and future of the Local Group of galaxies but also to challenge the fundamental assumption that luminosity traces the mass of the galaxies. Though many have proposed that the next generation telescopes capable of measuring 10^20 μas angular displacements in a year for faint continuum sources would be necessary, Brunthaler et al. (2005), Sjouwerman et al. (2010), and Darling (2011) showed that using point-like water or methanol masers are an alternative when using current instruments, providing continuous astrometric beacons which could be tracked over time. We will present results of new extragalactic methanol masers discovered with the VLA and future goals of this project.

Talk slides

Authors: Montana N. Williams (NMT), J. D. Linford (NRAO), K.V. Sokolovsky (University of Illinois at Urbana-Champaign), S. Lawrence (Hofstra University), L. Chomiuk (Michigan State University), J. L. Sokoloski (Columbia University), K. Mukai (NASA/GSFC), J. Bright (University of Oxford), R. Fender (University of Oxford), E. Aydi (Michigan State University), A. Kawash (Michigan State University), A. Mioduszewski (NRAO)

Abstract: V392Per is an unusual nova that erupted on April 29, 2018. It is a Neon nova detected by the Fermi Gamma-ray Telescope. The stellar system has a relatively long orbital period of 3.4 days. The white dwarf is ~1.2 solar masses, with a early red giant companion. We created a radio light curve of the nova using the Karl G. Jansky Very Large Arrayand Arcminute Microkelvin Imager Large Array. Observations from the Very Long Baseline Array (VLBA), starting at 18 days post nova, allow us to follow the morphology of the non-thermal components and measure the expansion rate to be ~1350 km/s. Additionally, we looked for morphological changes over the course of a single VLBA observations. The VLBA images show changes in morphology over the course of the observation. Furthermore, we have narrow band optical imaging from the Hubble Space Telescope (HST) Wide Field Camera 3, where the nova seems to be spatially unresolved and dominated by continuum emission. However, we also obtained spatially resolved optical spectra from HST’s Space Telescope Imaging Spectrograph, which show faint low-velocity emission in the Balmer and Helium lines, but high-velocity double-lobed structure in [OIII].

Authors: Avery Eddins (TTU), Kyung-Hwan Lee (Pohang University of Science and Technology), Alessandra Corsi (TTU), Imre Bartos (University of Florida), Zsuzsanna Marka (Columbia University), Szabolcs Marka (Columbia University)

Abstract: Following the discovery of the remarkable binary neutron star merger GW170817 by the LIGO and Virgo collaborations, much research has been conducted to uncover the nature of its post-merger remnant. GW170817 was accompanied by a gamma-ray burst (GRB), an optical kilonova, and a radio-to-X-ray-emitting structured jet. Several theoretical scenarios predict that, once the jet emission fades sufficiently, the kilonova ejecta itself may power a late-time radio flare associated with the fastest ejecta tail. This late-time radio emission can reveal important information on the nature of the post-merger remnant (neutron star versus black hole) and can be used as a tool to find nearby, GW170817-like neutron star mergers years after they have occurred. There is a possibility that such mergers went unrecognized when they occurred, as afterglows of nearby, off-axis mergers seem to arise, as shown by GW170817, after typical multi-wavelength monitoring of the GRB has ceased. In this context, I will present the results of an observing campaign carried out with the Jansky VLA aimed at determining whether short GRBs in the Swift/BAT sample lacking accurate localization, ones with no detected afterglow, could have originated from events like GW170817.

Talk slides

Authors: Frank Schinzel (NRAO/UNM), Greg Taylor (UNM), Matthew Kerr (NRL), Daniel Castro (CfA/Harvard), Urvashi Rau (NRAO), Sanjay Bhatnagar (NRAO)

Abstract: We have made X-ray and radio observations of a newly discovered supersonic pulsar PSR J0002+6216, using Chandra and the Very Large Array (VLA), which presents a simple geometry to study the morphology of the bow shock region, and to look for evidence of in-situ particle acceleration and synchrotron cooling along the tail of the bow shock. The X-ray data provide marginal evidence for the evolution of the Pulsar Wind Nebula (PWN) emission along the tail, with spectral slope changes consistent with synchrotron cooling. Radio observations show the presence of an extended bow shock and tail region in radio continuum images, imaged using combined broad-band radio data, taken in B, C and D configurations of the VLA.The high-resolution, long-baseline data reveal asymmetric, resolved structure around the pulsar, in the bow shock region. The radio images also shows disruption of the extended tail produced by the supersonic motion of the pulsar, which points towards anomalous feature of the ISM. Based on our spectral index maps obtained within the 4-12 GHz band, the PWN shows some unusual features including an unresolved flat spectrum component.

Talk slides

Authors: Alex Tetarenko (TTU), Andrew Hughes (University of Alberta), Greg Sivakoff (University of Alberta), James Miller-Jones (ICRAR, Australia), Mike McCollough (CfA)

Abstract: Black hole X-ray binaries are accreting objects that launch powerful relativistic jets. These binary systems evolve through bright outburst phases on rapid timescales of days to months, allowing us to probe jet/accretion phenomena in real time. While emission from the accretion flow dominates at shorter wavelengths (X-ray), synchrotron jet emission, which can be strongly polarized, dominates at longer wavelengths (radio, submm, infrared/optical). As such, polarization measurements can allow us to extract much more information about these jets than we can infer from just the total intensity of the emission (e.g., orientation of the jet, magnetic field strength and structure of both the jet and the surrounding medium, shock and plasma conditions in the jet flow). However, to date, such jet polarization studies are still quite limited, and are often hampered by complicating external effects (Faraday rotation, time variability). In this talk, I will discuss some of the latest exciting results working to overcome the above mentioned issues, and how current and next generation instrumentation can open up a new polarimetric viewpoint on X-ray binary jets that has yet to be thoroughly explored.

Authors: Evan Sheldahl (UNM), Gregory Taylor (UNM), Sebastian Kiehlmann (Foundation for Research and Technology-Hellas, Greece; University of Crete), Yannis Liodakis (University of Turku, Finland), Matt Lister (Purdue University), Sandra O’Neill (OVRO, Caltech), Tim Pearson (OVRO, Caltech), Anthony Readhead (OVRO, Caltech), Aneta Siemiginowska (CfA), Peter Wilkinson (Jodrell Bank, University of Manchester)

Abstract: Compact symmetric objects (CSOs) are a specific type of radio-loud active galactic nuclei (AGN) that are less than 1 kiloparsec in size and have their radio jets aligned close to the plane of the sky as to appear symmetrical about their center of emission. This is in contrast to the vast majority of known radio AGN, whose jets are pointed closer to our line of sight, introducing temporal variability and resulting in a ’core-jet’ morphology where only one jet is visible. Due to kinematic studies, we also know radio jets from CSOs are short-lived, with a majority of them being only a few thousand years old at most. Because of the small size of CSOs, the fact that their sizes can be verified more easily since they are edge-on, and their short-lived radio emission, they are ideal for studying how galaxies and jets evolve and affect their immediate surroundings. In order to contribute to the list of known CSOs, we searched through the literature for mentions of CSOs and other compact radio sources and observed about 170 different CSO candidate sources using the Very Long Baseline Array (VLBA). By creating high-resolution images and spectral index maps of these sources, we can distinguish their various morphological components with the hope of determining which of the candidates are bona fide CSOs.

Talk slides

Authors: Chris Nolting (LANL), Jay Ball (College of Charleston), Tri Nguyen (College of Charleston)

Abstract: et precession is sometimes invoked to explain asymmetries in radio galaxy jets and ’X/S/Z-shape’ radio galaxies, caused by the presence of a binary black hole companion to the source active galactic nucleus or by accretion instabilities. I will present a series of simulations of radio galaxy jet precession to examine how these sources would evolve over time, including a passive distribution of cosmic ray electrons so we can model radio synchrotron emissions and create synthetic radio maps of the sources. A single radio source viewed from different angles can result in differing radio galaxy morphological classifications, confusing physical implications of these classifications. Additionally, the jet trajectories can become unstable due to their own self-interactions and lead to ’reorientation events’ that may look like the effects of external dynamics such as shocks, winds, or cold fronts in the medium. Finally, something akin to an ’Odd Radio Circle’ may be observed in the case of viewing the radio remnant of such a precessing source from a line of sight near the precession axis.
See also arXiv:2301.04343

Talk slides (pptx)