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Absolute Flux Density Calibration of the Greenland Telescope Data for Event Horizon Telescope Observations
J. Y. Koay, K. Asada, S. Matsushita +35
Starting from the observing campaign in April 2018, the Greenland Telescope (GLT) has been added as a new station of the Event Horizon Telescope (EHT) array. Visibilities on baseli…
First M87 Event Horizon Telescope Results. IX. Detection of Near-horizon Circular Polarization
The Event Horizon Telescope Collaboration
Event Horizon Telescope (EHT) observations have revealed a bright ring of emission around the supermassive black hole at the center of the M87 galaxy. EHT images in linear polariza…
Polarimetric Geometric Modeling for mm-VLBI Observations of Black Holes
Freek Roelofs, Michael D. Johnson, Andrew Chael +4
The Event Horizon Telescope (EHT) is a millimeter very long baseline interferometry (VLBI) array that has imaged the apparent shadows of the supermassive black holes M87* and Sagit…
First Sagittarius A* Event Horizon Telescope Results. VI: Testing the Black Hole Metric
The Event Horizon Telescope Collaboration
Astrophysical black holes are expected to be described by the Kerr metric. This is the only stationary, vacuum, axisymmetric metric, without electromagnetic charge, that satisfies…
First Sagittarius A* Event Horizon Telescope Results. III: Imaging of the Galactic Center Supermassive Black Hole
The Event Horizon Telescope Collaboration
We present the first event-horizon-scale images and spatiotemporal analysis of Sgr A* taken with the Event Horizon Telescope in 2017 April at a wavelength of 1.3 mm. Imaging of Sgr…
First Sagittarius A* Event Horizon Telescope Results. V. Testing Astrophysical Models of the Galactic Center Black Hole
The Event Horizon Telescope Collaboration
In this paper, we provide a first physical interpretation for the Event Horizon Telescope (EHT)'s 2017 observations of Sgr A*. Our main approach is to compare resolved EHT data at…
First Sagittarius A* Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole in the Center of the Milky Way
The Event Horizon Telescope Collaboration
We present the first Event Horizon Telescope (EHT) observations of Sagittarius A* (Sgr A), the Galactic center source associated with a supermassive black hole. These observati…
First Sagittarius A* Event Horizon Telescope Results. IV. Variability, Morphology, and Black Hole Mass
The Event Horizon Telescope Collaboration
In this paper we quantify the temporal variability and image morphology of the horizon-scale emission from Sgr A*, as observed by the EHT in 2017 April at a wavelength of 1.3 mm. W…
Observations of Low and Intermediate Spectral Peak Blazars with the Imaging X-ray Polarimetry Explorer
Herman L. Marshall, Ioannis Liodakis, Alan P. Marscher +145
We present X-ray polarimetry observations from the Imaging X-ray Polarimetry Explorer (IXPE) of three low spectral peak and one intermediate spectral peak blazars, namely 3C 273, 3…
Magnetic Field Properties inside the Jet of Mrk 421: Multiwavelength Polarimetry Including the Imaging X-ray Polarimetry Explorer
Dawoon E. Kim, Laura Di Gesu, Ioannis Liodakis +133
We conducted a polarimetry campaign from radio to X-ray wavelengths of the high-synchrotron-peak (HSP) blazar Mrk 421, including Imaging X-ray Polarimetry Explorer (IXPE) measureme…
X-ray Polarization of the BL Lac Type Blazar 1ES 0229+200
Steven R. Ehlert, Ioannis Liodakis, Riccardo Middei +110
We present polarization measurements in the band from blazar 1ES 0229+200, the first extreme high synchrotron peaked source to be observed by the Imag…
A search for pulsars around Sgr A* in the first Event Horizon Telescope dataset
Pablo Torne, Kuo Liu, Ralph P. Eatough +282
The Event Horizon Telescope (EHT) observed in 2017 the supermassive black hole at the center of the Milky Way, Sagittarius A* (Sgr A*), at a frequency of 228.1 GHz (=1.3 mm). Th…
IXPE and multi-wavelength observations of blazar PG 1553+113 reveal an orphan optical polarization swing
Riccardo Middei, Matteo Perri, Simonetta Puccetti +119
The lower energy peak of the spectral energy distribution of blazars has commonly been ascribed to synchrotron radiation from relativistic particles in the jets. Despite the consen…
The Greenland Telescope: Construction, Commissioning, and Operations in Pituffik
Ming-Tang Chen, Keiichi Asada, Satoki Matsushita +51
In 2018, the Greenland Telescope (GLT) started scientific observation in Greenland. Since then, we have completed several significant improvements and added new capabilities to the…
Millimeter Observations of the Type II SN2023ixf: Constraints on the Proximate Circumstellar Medium
Edo Berger, Garrett K. Keating, Raffaella Margutti +10
We present 1.3 mm (230 GHz) observations of the recent and nearby Type II supernova, SN2023ixf, obtained with the Submillimeter Array (SMA) at 2.6-18.6 days after explosion. The ob…
Discovery of X-ray polarization angle rotation in active galaxy Mrk 421
Laura Di Gesu, Herman L. Marshall, Steven R. Ehlert +140
The magnetic field conditions in astrophysical relativistic jets can be probed by multiwavelength polarimetry, which has been recently extended to X-rays. For example, one can trac…
The JCMT BISTRO Survey: Studying the Complex Magnetic Field of L43
Janik Karoly, Derek Ward-Thompson, Kate Pattle +155
We present observations of polarized dust emission at 850 m from the L43 molecular cloud which sits in the Ophiuchus cloud complex. The data were taken using SCUBA-2/POL-2 on th…
Testing the linear relationship between black hole mass and variability timescale in low-luminosity AGN at submillimeter wavelengths
Bo-Yan Chen, Geoffrey C. Bower, Jason Dexter +5
The variability of submillimeter emission provides a useful tool to probe the accretion physics in low-luminosity active galactic nuclei. We accumulate four years of observations u…
X-ray Polarization of BL Lacertae in Outburst
Abel L. Peirson, Michela Negro, Ioannis Liodakis +128
We report the first confidence detection of X-ray polarization in BL Lacertae. During a recent X-ray/-ray outburst, a 287 ksec observation (2022 November 27-30) was tak…
A ring-like accretion structure in M87 connecting its black hole and jet
Ru-Sen Lu, Keiichi Asada, Thomas P. Krichbaum +118
The nearby radio galaxy M87 is a prime target for studying black hole accretion and jet formation^{1,2}. Event Horizon Telescope observations of M87 in 2017, at a wavelength of 1.3…
Comparison of Polarized Radiative Transfer Codes used by the EHT Collaboration
Cora Prather, Jason Dexter, Monika Moscibrodzka +270
Interpretation of resolved polarized images of black holes by the Event Horizon Telescope (EHT) requires predictions of the polarized emission observable by an Earth-based instrume…
First BISTRO observations of the dark cloud Taurus L1495A-B10: the role of the magnetic field in the earliest stages of low-mass star formation
Derek Ward-Thompson, Janik Karoly, Kate Pattle +155
We present BISTRO Survey 850 μm dust emission polarisation observations of the L1495A-B10 region of the Taurus molecular cloud, taken at the JCMT. We observe a roughly triangular n…
The Event Horizon Telescope Image of the Quasar NRAO 530
Svetlana Jorstad, Maciek Wielgus, Rocco Lico +27
We report on the observations of the quasar NRAO 530 with the Event Horizon Telescope (EHT) on 2017 April 5-7, when NRAO 530 was used as a calibrator for the EHT observations of Sa…