Millimeter Light Curves of Sagittarius A* Observed during the 2017 Event Horizon Telescope Campaign

Astronomy & Astrophysics

Context 3C 84 is a nearby radio source with a complex total intensity structure, showing linear polarisation and spectral patterns. A detailed investigation of the central engine region necessitates the use of very-long-baseline interferometry (VLBI) above the hitherto available maximum frequency of 86 GHz.Aims Using ultrahigh resolution VLBI observations at the currently highest available frequency of 228 GHz, we aim to perform a direct detection of compact structures and understand the physical conditions in the compact region of 3C 84.Methods We used Event Horizon Telescope (EHT) 228 GHz observations and, given the limited (u, v)-coverage, applied geometric model fitting to the data. Furthermore, we employed quasi-simultaneously observed, ancillary multi-frequency VLBI data for the source in order to carry out a comprehensive analysis of the core structure.Results We report the detection of a highly …

Astronomy & Astrophysics

We present the results of the first X-ray polarimetric observation of the low-mass X-ray binary 4U 1957+115, performed with the Imaging X-ray Polarimetry Explorer in May 2023. The binary system has been in a high-soft spectral state since its discovery and is thought to host a black hole. The ∼571 ks observation reveals a linear polarisation degree of 1.9%±0.6% and a polarisation angle of in the 2–8 keV energy range. Spectral modelling is consistent with the dominant contribution coming from the standard accretion disc, while polarimetric data suggest a significant role of returning radiation: photons that are bent by strong gravity effects and forced to return to the disc surface, where they can be reflected before eventually reaching the observer. In this setting, we find that models with a black hole spin lower than 0.96 and an inclination lower than 50° are disfavoured.

arXiv preprint arXiv:2403.17925

We forecast constraints on cosmological parameters enabled by three surveys conducted with SPT-3G, the third-generation camera on the South Pole Telescope. The surveys cover separate regions of 1500, 2650, and 6000 to different depths, in total observing 25% of the sky. These regions will be measured to white noise levels of roughly 2.5, 9, and 12 , respectively, in CMB temperature units at 150 GHz by the end of 2024. The survey also includes measurements at 95 and 220 GHz, which have noise levels a factor of ~1.2 and 3.5 times higher than 150 GHz, respectively, with each band having a polarization noise level ~ times higher than the temperature noise. We use a novel approach to obtain the covariance matrices for jointly and optimally estimated gravitational lensing potential bandpowers and unlensed CMB temperature and polarization bandpowers. We demonstrate the ability to test the model via the consistency of cosmological parameters constrained independently from SPT-3G and Planck data, and consider the improvement in constraints on extension parameters from a joint analysis of SPT-3G and Planck data. The cosmological parameters are typically constrained with uncertainties up to ~2 times smaller with SPT-3G data, compared to Planck, with the two data sets measuring significantly different angular scales and polarization levels, providing additional tests of the standard cosmological model.

The Astrophysical Journal

We present high-cadence optical and ultraviolet (UV) observations of the Type II supernova (SN), SN 2022jox which exhibits early spectroscopic high-ionization flash features of H i, He ii, C iv, and N iv that disappear within the first few days after explosion. SN 2022jox was discovered by the Distance Less Than 40 Mpc survey∼ 0.75 day after explosion with follow-up spectra and UV photometry obtained within minutes of discovery. The SN reached a peak brightness of M V∼− 17.3 mag, and has an estimated 56 Ni mass of 0.04 M⊙, typical values for normal Type II SNe. The modeling of the early light curve and the strong flash signatures present in the optical spectra indicate interaction with circumstellar material (CSM) created from a progenitor with a mass-loss rate of $\dot {M}\sim {10}^{-3}{\textstyle {\unicode {x02013}}}{10}^{-2}\text {}{M} _ {\odot}\,{{\rm {y}}{\rm {r}}}^{-1} $

Astronomy & Astrophysics

In April 2019, the Event Horizon Telescope (EHT) Collaboration reported the first-ever event-horizon-scale images of a black hole, resolving the central compact radio source in the giant elliptical galaxy M 87. These images reveal a ring with a southerly brightness distribution and a diameter of ∼42 μas, consistent with the predicted size and shape of a shadow produced by the gravitationally lensed emission around a supermassive black hole. These results were obtained as part of the April 2017 EHT observation campaign, using a global very long baseline interferometric radio array operating at a wavelength of 1.3 mm. Here, we present results based on the second EHT observing campaign, taking place in April 2018 with an improved array, wider frequency coverage, and increased bandwidth. In particular, the additional baselines provided by the Greenland telescope improved the coverage of the array. Multiyear …

Transient Name Server Classification Report

Global SN Project Transient Classification Report for 2022-08-24 - NASA/ADS Now on home page ads icon ads Enable full ADS view NASA/ADS Global SN Project Transient Classification Report for 2022-08-24 Shrestha, M. ; Jha, SW ; Hosseinzadeh, G. ; Sand, DJ ; Brown, PJ Abstract Publication: Transient Name Server Classification Report Pub Date: August 2022 Bibcode: 2022TNSCR2449....1S Keywords: Transient; 2022ryi; AT2022ryi; AT 2022ryi full text sources Publisher | data products TNS (1) © The SAO/NASA Astrophysics Data System adshelp[at]cfa.harvard.edu The ADS is operated by the Smithsonian Astrophysical Observatory under NASA Cooperative Agreement NNX16AC86A NASA logo Smithsonian logo Resources About ADS ADS Help What's New Careers@ADS Social @adsabs ADS Blog Project Switch to full ADS Is ADS down? (or is it just me...) Smithsonian Institution Smithsonian Privacy …

ICLR 2024

Deep features are a cornerstone of computer vision research, capturing image semantics and enabling the community to solve downstream tasks even in the zero- or few-shot regime. However, these features often lack the spatial resolution to directly perform dense prediction tasks like segmentation and depth prediction because models aggressively pool information over large areas. In this work, we introduce FeatUp, a task- and model-agnostic framework to restore lost spatial information in deep features. We introduce two variants of FeatUp: one that guides features with high-resolution signal in a single forward pass, and one that fits an implicit model to a single image to reconstruct features at any resolution. Both approaches use a multi-view consistency loss with deep analogies to NeRFs. Our features retain their original semantics and can be swapped into existing applications to yield resolution and performance gains even without re-training. We show that FeatUp significantly outperforms other feature upsampling and image super-resolution approaches in class activation map generation, transfer learning for segmentation and depth prediction, and end-to-end training for semantic segmentation.

Astronomy & Astrophysics

Context 3C 84 is a nearby radio source with a complex total intensity structure, showing linear polarisation and spectral patterns. A detailed investigation of the central engine region necessitates the use of very-long-baseline interferometry (VLBI) above the hitherto available maximum frequency of 86 GHz.Aims Using ultrahigh resolution VLBI observations at the currently highest available frequency of 228 GHz, we aim to perform a direct detection of compact structures and understand the physical conditions in the compact region of 3C 84.Methods We used Event Horizon Telescope (EHT) 228 GHz observations and, given the limited (u, v)-coverage, applied geometric model fitting to the data. Furthermore, we employed quasi-simultaneously observed, ancillary multi-frequency VLBI data for the source in order to carry out a comprehensive analysis of the core structure.Results We report the detection of a highly …

arXiv preprint arXiv:2402.08402

The Blandford-Znajek (BZ) process powers energetic jets by extracting the rotating energy of a Kerr black hole. It is important to understand this process in non-Kerr black hole spacetimes. In this study, we conduct two-dimensional and three-dimensional two-temperature General Relativistic Magnetohydrodynamic (GRMHD) simulations of magnetized accretion flows onto a rotating Loop-Quantum black hole (LQBH). Our investigation focuses on the accretion flow structure and jet launching dynamics from our simulations. We observe that the loop quantum effects increase the black hole angular frequency for spinning black holes.This phenomenon intensifies the frame-dragging effect, leading to an amplification of the toroidal magnetic field within the funnel region and enhancement of the launching jet power. It is possible to fit the jet power following a similar fitting formula of the black hole angular frequency as seen in the Kerr black hole. Based on the General Relativistic Radiation Transfer (GRRT) calculation, we find that the jet image from LQBH has a wider opening angle and an extended structure than the Kerr BH.

Astronomy & Astrophysics

Context 3C 84 is a nearby radio source with a complex total intensity structure, showing linear polarisation and spectral patterns. A detailed investigation of the central engine region necessitates the use of very-long-baseline interferometry (VLBI) above the hitherto available maximum frequency of 86 GHz.Aims Using ultrahigh resolution VLBI observations at the currently highest available frequency of 228 GHz, we aim to perform a direct detection of compact structures and understand the physical conditions in the compact region of 3C 84.Methods We used Event Horizon Telescope (EHT) 228 GHz observations and, given the limited (u, v)-coverage, applied geometric model fitting to the data. Furthermore, we employed quasi-simultaneously observed, ancillary multi-frequency VLBI data for the source in order to carry out a comprehensive analysis of the core structure.Results We report the detection of a highly …

arXiv preprint arXiv:2401.02075

We present cosmological constraints from the abundance of galaxy clusters selected via the thermal Sunyaev-Zel'dovich (SZ) effect in South Pole Telescope (SPT) data with a simultaneous mass calibration using weak gravitational lensing data from the Dark Energy Survey (DES) and the Hubble Space Telescope (HST). The cluster sample is constructed from the combined SPT-SZ, SPTpol ECS, and SPTpol 500d surveys, and comprises 1,005 confirmed clusters in the redshift range over a total sky area of 5,200 deg. We use DES Year 3 weak-lensing data for 688 clusters with redshifts and HST weak-lensing data for 39 clusters with . The weak-lensing measurements enable robust mass measurements of sample clusters and allow us to empirically constrain the SZ observable--mass relation. For a flat CDM cosmology, and marginalizing over the sum of massive neutrinos, we measure , , and the parameter combination . Our measurement of and the constraint from Planck CMB anisotropies (2018 TT,TE,EE+lowE) differ by . In combination with that Planck dataset, we place a 95% upper limit on the sum of neutrino masses eV. When additionally allowing the dark energy equation of state parameter to vary, we obtain from our cluster-based analysis. In combination with Planck data, we measure , or a difference with a cosmological constant. We use the cluster abundance to measure in five redshift bins between 0.25 and 1.8, and we find the results to be consistent with structure growth as …

The Astrophysical Journal

Horizon-scale observations from the Event Horizon Telescope (EHT) have enabled precision study of supermassive black hole accretion. Contemporary accretion modeling often treats the inflowing plasma as a single, thermal fluid, but microphysical kinetic effects can lead to significant deviations from this idealized picture. We investigate how the helicity barrier influences EHT-accessible electromagnetic observables by employing a simple model for electron heating based on kinetic physics and the cascade of energy and helicity in unbalanced turbulence. Although the helicity barrier plays only a minor role in regions with high plasma β, like in standard and normal evolution (SANE) disks, it may substantially impact regions with more ordered magnetic fields, such as the jet and its surrounding wind in SANE flows as well as throughout the entire domain in magnetically arrested disk (MAD) flows. In SANE flows …

VizieR Online Data Catalog

FITS files of the representative image of M 87* from the EHT observations taken on 2018 April 21 at band 3, as found in Figure 1 of the paper. The image is created by averaging together the blurred images from each of the methods described in Sect. 5 of the paper.

The Astrophysical Journal

The Event Horizon Telescope (EHT) Collaboration has recently published the first horizon-scale images of the supermassive black holes M87* and Sgr A* and provided some first information on the physical conditions in their vicinity. The comparison between the observations and the three-dimensional general relativistic magnetohydrodynamic (GRMHD) simulations has enabled the EHT to set initial constraints on the properties of these black hole spacetimes. However, accurately distinguishing the properties of the accretion flow from those of the spacetime, most notably, the black hole mass and spin, remains challenging because of the degeneracies the emitted radiation suffers when varying the properties of the plasma and those of the spacetime. The next-generation EHT (ngEHT) observations are expected to remove some of these degeneracies by exploring the complex interplay between the disk–jet …

The Astrophysical Journal Letters

First Sagittarius A* Event Horizon Telescope Results. VII. Polarization of the Ring - IOPscience Skip to content IOP Science home Accessibility Help Search Journals Journals list Browse more than 100 science journal titles Subject collections Read the very best research published in IOP journals Publishing partners Partner organisations and publications Open access IOP Publishing open access policy guide IOP Conference Series Read open access proceedings from science conferences worldwide Books Publishing Support Login IOPscience login / Sign Up Click here to close this panel. Search Primary search Search all IOPscience content Article Lookup Select journal (required) Volume number: Issue number (if known): Article or page number: The Astrophysical Journal Letters The American Astronomical Society, find out more. The American Astronomical Society logo. The American Astronomical Society (AAS)…

Information and Learning Sciences

PurposeData storytelling courses position students as agents in creating stories interpreted from data about a social problem or social justice issue. The purpose of this study is to explore two research questions: What themes characterized students’ iterative development of data story topics? Looking back at six years of iterative feedback, what categories of data literacy pedagogy did instructors engage for these themes?.Design/methodology/approachThis project examines six years of data storytelling final projects using thematic analysis and three years of instructor feedback. Ten themes in final projects align with patterns in feedback. Reflections on pedagogical approaches to students’ topic development suggest extending data literacy pedagogy categories – formal, personal and folk (Pangrazio and Sefton-Green, 2020).FindingsData storytelling can develop students’ abilities to move from being consumers to …

Monthly Notices of the Royal Astronomical Society

We present a study of the co-evolution of a population of primordial star-forming minihaloes at Cosmic Dawn. In this study, we highlight the influence of individual Population III stars on the ability of nearby minihaloes to form sufficient molecular hydrogen to undergo star formation. In the absence of radiation, we find the minimum halo mass required to bring about collapse to be ∼105 M⊙, this increases to ∼106 M⊙ after two stars have formed. We find an inverse relationship between halo mass and the time required for it to recover its molecular gas after being disrupted by radiation from a nearby star. We also take advantage of the extremely high resolution to investigate the effects of major and minor mergers on the gas content of star-forming minihaloes. Contrary to previous claims of fallback of supernova ejecta, we find minihaloes evacuated after hosting Pop III stars primarily recover gas through mergers …

Monthly Notices of the Royal Astronomical Society

The development of a neutrino moment-based radiative-transfer code to simulate binary neutron star mergers can easily become an obstacle path because of the numerous ways in which the solution of the equations may fail. We describe the implementation of the grey M1 scheme in our fully general-relativistic magnetohydrodynamics code and detail those choices and strategies that could lead either to a robust scheme or to a series of failures. In addition, we present new tests designed to show the consistency and accuracy of our code in conditions that are similar to realistic merging conditions and introduce a new, publicly available, benchmark based on the head-on collision of two neutron stars. This test, which is computationally less expensive than a complete merging binary but has all the potential pitfalls of the full scenario, can be used to compare future implementations of M1 schemes with the one …

The Astrophysical Journal

The Event Horizon Telescope (EHT) Collaboration has recently published the first horizon-scale images of the supermassive black holes M87* and Sgr A* and provided some first information on the physical conditions in their vicinity. The comparison between the observations and the three-dimensional general relativistic magnetohydrodynamic (GRMHD) simulations has enabled the EHT to set initial constraints on the properties of these black hole spacetimes. However, accurately distinguishing the properties of the accretion flow from those of the spacetime, most notably, the black hole mass and spin, remains challenging because of the degeneracies the emitted radiation suffers when varying the properties of the plasma and those of the spacetime. The next-generation EHT (ngEHT) observations are expected to remove some of these degeneracies by exploring the complex interplay between the disk–jet …

Astronomy & Astrophysics

Context 3C 84 is a nearby radio source with a complex total intensity structure, showing linear polarisation and spectral patterns. A detailed investigation of the central engine region necessitates the use of very-long-baseline interferometry (VLBI) above the hitherto available maximum frequency of 86 GHz.Aims Using ultrahigh resolution VLBI observations at the currently highest available frequency of 228 GHz, we aim to perform a direct detection of compact structures and understand the physical conditions in the compact region of 3C 84.Methods We used Event Horizon Telescope (EHT) 228 GHz observations and, given the limited (u, v)-coverage, applied geometric model fitting to the data. Furthermore, we employed quasi-simultaneously observed, ancillary multi-frequency VLBI data for the source in order to carry out a comprehensive analysis of the core structure.Results We report the detection of a highly …

The Astrophysical Journal Letters

In this Letter, we report the discovery of the highest redshift, heavily obscured, radio-loud (RL) active galactic nucleus (AGN) candidate selected using JWST NIRCam/MIRI, mid-IR, submillimeter, and radio imaging in the COSMOS-Web field. Using multifrequency radio observations and mid-IR photometry, we identify a powerful, RL, growing supermassive black hole with significant spectral steepening of the radio spectral energy distribution (f 1.28 GHz∼ 2 mJy, q 24 μm=− 1.1, α 1.28− 3 GHz=− 1.2, Δα=− 0.4). In conjunction with ALMA, deep ground-based observations, ancillary space-based data, and the unprecedented resolution and sensitivity of JWST, we find no evidence of AGN contribution to the UV/optical/near-infrared (NIR) data and thus infer heavy amounts of obscuration (N H> 10 23 cm− 2). Using the wealth of deep UV to submillimeter photometric data, we report a singular solution photo-z of z phot=

The Astrophysical Journal Letters

Stars that formed with an initial mass of over 50 M⊙ are very rare today, but they are thought to be more common in the early Universe. The fates of those early, metal-poor, massive stars are highly uncertain. Most are expected to directly collapse to black holes, while some may explode as a result of rotationally powered engines or the pair-creation instability. We present the chemical abundances of J0931+ 0038, a nearby low-mass star identified in early follow-up of the SDSS-V Milky Way Mapper, which preserves the signature of unusual nucleosynthesis from a massive star in the early Universe. J0931+ 0038 has a relatively high metallicity ([Fe/H]=− 1.76±0.13) but an extreme odd–even abundance pattern, with some of the lowest known abundance ratios of [N/Fe],[Na/Fe],[K/Fe],[Sc/Fe], and [Ba/Fe]. The implication is that a majority of its metals originated in a single extremely metal-poor nucleosynthetic source. An …

The Astrophysical Journal Letters

We present the first detection in space of thionylimide (HNSO) toward the Galactic center molecular cloud G+ 0.693-0.027, thanks to the superb sensitivity of an ultradeep molecular line survey carried out with the Yebes 40 m and IRAM 30 m telescopes. This molecule is the first species detected in the interstellar medium containing, simultaneously, N, S, and O. We have identified numerous K a= 0, 1, and 2 transitions belonging to HNSO covering from J up= 2 to J up= 10, including several completely unblended features. We derive a molecular column density of N=(8±1)× 10 13 cm− 2, yielding a fractional abundance relative to H 2 of∼ 6× 10− 10, which is about∼ 37 and∼ 4.8 times less abundant than SO and SO 2, respectively. Although there are still many unknowns in the interstellar chemistry of NSO-bearing molecules, we propose that HNSO is likely formed through the reaction of the NSO radical and atomic H …

The Astrophysical journal letters

The Imaging X-ray Polarimetry Explorer measured with high significance the X-ray polarization of the brightest Z-source, Sco X-1, resulting in the nominal 2–8 keV energy band in a polarization degree of 1.0%±0.2% and a polarization angle of 8±6 at a 90% confidence level. This observation was strictly simultaneous with observations performed by NICER, NuSTAR, and Insight-HXMT, which allowed for a precise characterization of its broadband spectrum from soft to hard X-rays. The source has been observed mainly in its soft state, with short periods of flaring. We also observed low-frequency quasiperiodic oscillations. From a spectropolarimetric analysis, we associate a polarization to the accretion disk at< 3.2% at 90% confidence level, compatible with expectations for an electron scattering dominated optically thick atmosphere at the Sco X-1 inclination of∼ 44; for the higher-energy Comptonized component, we …

The Astrophysical Journal Letters

Recently we found compelling evidence for a gravitational-wave background with Hellings and Downs (HD) correlations in our 15 yr data set. These correlations describe gravitational waves as predicted by general relativity, which has two transverse polarization modes. However, more general metric theories of gravity can have additional polarization modes, which produce different interpulsar correlations. In this work, we search the NANOGrav 15 yr data set for evidence of a gravitational-wave background with quadrupolar HD and scalar-transverse (ST) correlations. We find that HD correlations are the best fit to the data and no significant evidence in favor of ST correlations. While Bayes factors show strong evidence for a correlated signal, the data does not strongly prefer either correlation signature, with Bayes factors∼ 2 when comparing HD to ST correlations, and∼ 1 for HD plus ST correlations to HD …

The Astrophysical Journal Letters

Recently we found compelling evidence for a gravitational-wave background with Hellings and Downs (HD) correlations in our 15 yr data set. These correlations describe gravitational waves as predicted by general relativity, which has two transverse polarization modes. However, more general metric theories of gravity can have additional polarization modes, which produce different interpulsar correlations. In this work, we search the NANOGrav 15 yr data set for evidence of a gravitational-wave background with quadrupolar HD and scalar-transverse (ST) correlations. We find that HD correlations are the best fit to the data and no significant evidence in favor of ST correlations. While Bayes factors show strong evidence for a correlated signal, the data does not strongly prefer either correlation signature, with Bayes factors∼ 2 when comparing HD to ST correlations, and∼ 1 for HD plus ST correlations to HD …

The Astrophysical Journal Letters

The discovery of extreme strontium isotope anomalies (μ 84 Sr) in refractory leachates from Allende fine-grained calcium-aluminum-rich inclusions (CAIs) is at odds with long-standing predictions regarding the homogenization of presolar components in the CAI-forming region. Elucidating the stellar source (s) of these phases and the mechanisms for their preservation holds potential significance in understanding the dynamics and evolution of the protoplanetary disk. Here we present barium isotope data for the same set of leachates previously analyzed for μ 84 Sr. Our results show fairly homogeneous Ba isotope anomalies across leachates (∼ 100–200 ppm variability), in contrast to the observed μ 84 Sr variations (up to∼ 8%). Secondary phases extracted in earlier leaching steps (L1 and L3) reveal trends in μ 137 Ba and μ 138 Ba akin to that of mainstream SiC and a second nucleosynthetic component. We show …

The Astrophysical Journal Letters

Optical surveys have become increasingly adept at identifying candidate tidal disruption events (TDEs) in large numbers, but classifying these generally requires extensive spectroscopic resources. Here we present tdescore, a simple binary photometric classifier that is trained using a systematic census of∼ 3000 nuclear transients from the Zwicky Transient Facility (ZTF). The sample is highly imbalanced, with TDEs representing∼ 2% of the total. tdescore is nonetheless able to reject non-TDEs with 99.6% accuracy, yielding a sample of probable TDEs with recall of 77.5% for a precision of 80.2%. tdescore is thus substantially better than any available TDE photometric classifier scheme in the literature, with performance not far from spectroscopy as a method for classifying ZTF nuclear transients, despite relying solely on ZTF data and multiwavelength catalog cross matching. In a novel extension, we use" Shapley …

The Astrophysical journal letters

Cir X-1 is a neutron star X-ray binary characterized by strong variations in flux during its eccentric∼ 16.6 day orbit. There are also strong variations in the spectral state, and it has historically shown both atoll and Z state properties. We observed the source with the Imaging X-ray Polarimetry Explorer during two orbital segments, 6 days apart, for a total of 263 ks. We find an X-ray polarization degree in these segments of 1.6%±0.3% and 1.4%±0.3% at polarization angles of 37±5 and− 12±7, respectively. Thus, we observed a rotation of the polarization angle by 49±8 along the orbit. Because variations of accretion flow, and then of the hardness ratio, are expected during the orbit, we also studied the polarization binned in hardness ratio and found the polarization angle differing by 67±11 between the lowest and highest values of the hardness ratio. We discuss possible interpretations of this result that could indicate a …

The Astrophysical Journal Letters

In situ observations of turbulence spectra in space plasmas are usually interpreted as wavenumber spectra, assuming that the fluctuation frequency is negligible in the plasma flow frame. We explore the effects of nonzero frequency in the plasma flow frame on turbulence spectral observations. The finite frequency can be caused by either propagating waves or nonlinear broadening of nonpropagating structures. We show that the observed frequency spectrum can be modified by the nonzero frequency of turbulent fluctuations in several ways. Specifically,(i) frequency broadening results in a minor modification to the observed spectrum, primarily acting as a smoothing kernel of the spectrum near the spectral break, while the asymptotic spectral index remains unchanged;(ii) wave propagation can affect the observed spectral index for anisotropic turbulence. The effect is significant at low frequencies and weaker at high …

The Astrophysical journal letters

Cir X-1 is a neutron star X-ray binary characterized by strong variations in flux during its eccentric∼ 16.6 day orbit. There are also strong variations in the spectral state, and it has historically shown both atoll and Z state properties. We observed the source with the Imaging X-ray Polarimetry Explorer during two orbital segments, 6 days apart, for a total of 263 ks. We find an X-ray polarization degree in these segments of 1.6%±0.3% and 1.4%±0.3% at polarization angles of 37±5 and− 12±7, respectively. Thus, we observed a rotation of the polarization angle by 49±8 along the orbit. Because variations of accretion flow, and then of the hardness ratio, are expected during the orbit, we also studied the polarization binned in hardness ratio and found the polarization angle differing by 67±11 between the lowest and highest values of the hardness ratio. We discuss possible interpretations of this result that could indicate a …

The Astrophysical Journal Letters

James Webb Space Telescope NIRCam images have revealed 154 reliable globular cluster (GC) candidates around the z= 0.0513 elliptical galaxy VV 191a after subtracting 34 likely interlopers from background galaxies inside our search area. NIRCam broadband observations are made at 0.9–4.5 μm using the F090W, F150W, F356W, and F444W filters. Using point-spread-function-matched photometry, the data are analyzed to present color–magnitude diagrams and color distributions that suggest a relatively uniform population of GCs, except for small fractions of reddest (5%–8%) and bluest (2%–4%) outliers. GC models in the F090W versus (F090W–F150W) diagram fit the NIRCam data well and show that the majority of GCs detected have a mass of∼ 10 6.5 M⊙, with metallicities [Fe/H] spanning the typical range expected for GCs (− 2.5≲[Fe/H]≲ 0.5). However, the models predict∼ 0.3–0.4 mag bluer …

The Astrophysical Journal Letters

Using the MIRI medium-resolution spectrometer on JWST, we have detected pure rotational, suprathermal OH emissions from the vicinity of the intermediate-mass protostar HOPS 370 (OMC2/FIR3). These emissions are observed from shocked knots in a jet/outflow and originate in states of rotational quantum number as high as 46 that possess excitation energies as large as E U/k= 4.65× 10 4 K. The relative strengths of the observed OH lines provide a powerful diagnostic of the ultraviolet radiation field in a heavily extinguished region (A V∼ 10–20) where direct UV observations are impossible. To high precision, the OH line strengths are consistent with a picture in which the suprathermal OH states are populated following the photodissociation of water in its

The Astrophysical Journal Letters

The evolved stages of massive stars are poorly understood, but invaluable constraints can be derived from spatially resolved observations of nearby red supergiants, such as Betelgeuse. Atacama Large Millimeter/submillimeter Array (ALMA) observations of Betelgeuse showing a dipolar velocity field have been interpreted as evidence for a projected rotation rate of about 5 km s− 1. This is 2 orders of magnitude larger than predicted by single-star evolution, which led to suggestions that Betelgeuse is a binary merger. We propose instead that large-scale convective motions can mimic rotation, especially if they are only partially resolved. We support this claim with 3D CO5BOLD simulations of nonrotating red supergiants that we postprocessed to predict ALMA images and SiO spectra. We show that our synthetic radial velocity maps have a 90% chance of being falsely interpreted as evidence for a projected rotation …

The Astrophysical Journal Letters

Investigating Protostellar Accretion (IPA) is a JWST Cycle 1 GO program that uses NIRSpec integral field units and MIRI Medium Resolution Spectrograph to obtain 2.9–28 μm spectral cubes of young, deeply embedded protostars with luminosities of 0.2–10,000 L⊙ and central masses of 0.15–12 M⊙. In this Letter, we report the discovery of a highly collimated atomic jet from the Class 0 protostar IRAS 16253− 2429, the lowest-luminosity source (L bol= 0.2 L⊙) in the IPA program. The collimated jet is detected in multiple [Fe ii] lines and [Ne ii],[Ni ii], and H i lines but not in molecular emission. The atomic jet has a velocity of about 169±15 km s− 1, after correcting for inclination. The width of the jet increases with distance from the central protostar from 23 to 60 au, corresponding to an opening angle of 2 fdg 6±0 fdg 5. By comparing the measured flux ratios of various fine-structure lines to those predicted by simple …

The Astrophysical Journal Letters

We present analysis of 17,043 proton kinetic-scale current sheets (CSs) collected over 124 days of Wind spacecraft measurements in the solar wind at 11 samples s− 1 magnetic field resolution. The CSs have thickness, λ, from a few tens to one thousand kilometers with typical values around 100 km, or within about 0.1–10λ p in terms of local proton inertial length, λ p. We found that the current density is larger for smaller-scale CSs, J 0≈ 6 nAm− 2·(λ/100 km)− 0.56, but does not statistically exceed a critical value, J A, corresponding to the drift between ions and electrons of local Alvén speed. The observed trend holds in normalized units:

The Astrophysical Journal Letters

We confirm TOI-4201 b as a transiting Jovian-mass planet orbiting an early M dwarf discovered by the Transiting Exoplanet Survey Satellite. Using ground-based photometry and precise radial velocities from NEID and the Planet Finder Spectrograph, we measure a planet mass of

The Astrophysical Journal Letters

Emission lines from Rydberg transitions are detected for the first time from a region close to the surface of Betelgeuse. The H30α line is observed at 231.905 GHz, with an FWHM∼ 42 km s− 1 and extended wings. A second line at 232.025 GHz (FWHM∼ 21 km s− 1), is modeled as a combination of Rydberg transitions of abundant low first ionization potential metals. Both H30α and the Rydberg combined line X30α are fitted by Voigt profiles, and collisional broadening with electrons may be partly responsible for the Lorentzian contribution, indicating electron densities of a few 10 8 cm− 3. X30α is located in a relatively smooth ring at a projected radius of 0.9× the optical photospheric radius R⋆, whereas H30α is more clumpy, reaching a peak at∼ 1.4 R⋆. We use a semiempirical thermodynamic atmospheric model of Betelgeuse to compute the 232 GHz (1.29 mm) continuum and line profiles making simple …

The Astrophysical Journal Letters

A wealth of observations have long suggested that the vast majority of isolated classical dwarf galaxies (M*= 10 7–10 9 M⊙) are currently star forming. However, recent observations of the large abundance of" ultra-diffuse galaxies" beyond the reach of previous large spectroscopic surveys suggest that our understanding of the dwarf galaxy population may be incomplete. Here we report the serendipitous discovery of an isolated quiescent dwarf galaxy in the nearby Universe, which was imaged as part of the JWST PEARLS Guaranteed Time Observation program. Remarkably, individual red-giant branch stars are visible in this near-IR imaging, suggesting a distance of 30±4 Mpc, and a wealth of archival photometry point to an sSFR of 2× 10− 11 yr− 1 and star formation rate of 4× 10− 4 M⊙ yr− 1. Spectra obtained with the Lowell Discovery Telescope find a recessional velocity consistent with the Hubble Flow and> …

The Astrophysical Journal Letters

In this Letter, we report the discovery of the highest redshift, heavily obscured, radio-loud (RL) active galactic nucleus (AGN) candidate selected using JWST NIRCam/MIRI, mid-IR, submillimeter, and radio imaging in the COSMOS-Web field. Using multifrequency radio observations and mid-IR photometry, we identify a powerful, RL, growing supermassive black hole with significant spectral steepening of the radio spectral energy distribution (f 1.28 GHz∼ 2 mJy, q 24 μm=− 1.1, α 1.28− 3 GHz=− 1.2, Δα=− 0.4). In conjunction with ALMA, deep ground-based observations, ancillary space-based data, and the unprecedented resolution and sensitivity of JWST, we find no evidence of AGN contribution to the UV/optical/near-infrared (NIR) data and thus infer heavy amounts of obscuration (N H> 10 23 cm− 2). Using the wealth of deep UV to submillimeter photometric data, we report a singular solution photo-z of z phot=