48 research outputs found
Rare and low-frequency coding variants alter human adult height
Height is a highly heritable, classic polygenic trait with ~700 common associated variants identified so far through genome - wide association studies . Here , we report 83 height - associated coding variants with lower minor allele frequenc ies ( range of 0.1 - 4.8% ) and effects of up to 2 16 cm /allele ( e.g. in IHH , STC2 , AR and CRISPLD2 ) , >10 times the average effect of common variants . In functional follow - up studies, rare height - increasing alleles of STC2 (+1 - 2 cm/allele) compromise d proteolytic inhibition of PAPP - A and increased cleavage of IGFBP - 4 in vitro , resulting in higher bioavailability of insulin - like growth factors . The se 83 height - associated variants overlap genes mutated in monogenic growth disorders and highlight new biological candidates ( e.g. ADAMTS3, IL11RA, NOX4 ) and pathways ( e.g . proteoglycan/ glycosaminoglycan synthesis ) involved in growth . Our results demonstrate that sufficiently large sample sizes can uncover rare and low - frequency variants of moderate to large effect associated with polygenic human phenotypes , and that these variants implicate relevant genes and pathways
SARS-CoV-2 susceptibility and COVID-19 disease severity are associated with genetic variants affecting gene expression in a variety of tissues
Variability in SARS-CoV-2 susceptibility and COVID-19 disease severity between individuals is partly due to
genetic factors. Here, we identify 4 genomic loci with suggestive associations for SARS-CoV-2 susceptibility
and 19 for COVID-19 disease severity. Four of these 23 loci likely have an ethnicity-specific component.
Genome-wide association study (GWAS) signals in 11 loci colocalize with expression quantitative trait loci
(eQTLs) associated with the expression of 20 genes in 62 tissues/cell types (range: 1:43 tissues/gene),
including lung, brain, heart, muscle, and skin as well as the digestive system and immune system. We perform
genetic fine mapping to compute 99% credible SNP sets, which identify 10 GWAS loci that have eight or fewer
SNPs in the credible set, including three loci with one single likely causal SNP. Our study suggests that the
diverse symptoms and disease severity of COVID-19 observed between individuals is associated with variants across the genome, affecting gene expression levels in a wide variety of tissue types
First Sagittarius A* Event Horizon Telescope Results. IV. Variability, Morphology, and Black Hole Mass
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. We find that the Sgr A* data exhibit variability that exceeds what can be explained by the uncertainties in the data or by the effects of interstellar scattering. The magnitude of this variability can be a substantial fraction of the correlated flux density, reaching ∼100% on some baselines. Through an exploration of simple geometric source models, we demonstrate that ring-like morphologies provide better fits to the Sgr A* data than do other morphologies with comparable complexity. We develop two strategies for fitting static geometric ring models to the time-variable Sgr A* data; one strategy fits models to short segments of data over which the source is static and averages these independent fits, while the other fits models to the full data set using a parametric model for the structural variability power spectrum around the average source structure. Both geometric modeling and image-domain feature extraction techniques determine the ring diameter to be 51.8 ± 2.3 μas (68% credible intervals), with the ring thickness constrained to have an FWHM between ∼30% and 50% of the ring diameter. To bring the diameter measurements to a common physical scale, we calibrate them using synthetic data generated from GRMHD simulations. This calibration constrains the angular size of the gravitational radius to be 4.8−0.7+1.4 μas, which we combine with an independent distance measurement from maser parallaxes to determine the mass of Sgr A* to be 4.0−0.6+1.1×106 M ⊙
The Event Horizon Telescope Image of the Quasar NRAO 530
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 Sagittarius A*. At z = 0.902, this is the most distant object imaged by the EHT so far. We reconstruct the first images of the source at 230 GHz, at an unprecedented angular resolution of ∼20 μas, both in total intensity and in linear polarization (LP). We do not detect source variability, allowing us to represent the whole data set with static images. The images reveal a bright feature located on the southern end of the jet, which we associate with the core. The feature is linearly polarized, with a fractional polarization of ∼5%–8%, and it has a substructure consisting of two components. Their observed brightness temperature suggests that the energy density of the jet is dominated by the magnetic field. The jet extends over 60 μas along a position angle ∼ −28°. It includes two features with orthogonal directions of polarization (electric vector position angle), parallel and perpendicular to the jet axis, consistent with a helical structure of the magnetic field in the jet. The outermost feature has a particularly high degree of LP, suggestive of a nearly uniform magnetic field. Future EHT observations will probe the variability of the jet structure on microarcsecond scales, while simultaneous multiwavelength monitoring will provide insight into the high-energy emission origin
First Sagittarius A* Event Horizon Telescope Results. VI. Testing the Black Hole Metric
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 Einstein’s equations and does not have pathologies outside of the event horizon. We present new constraints on potential deviations from the Kerr prediction based on 2017 EHT observations of Sagittarius A* (Sgr A*). We calibrate the relationship between the geometrically defined black hole shadow and the observed size of the ring-like images using a library that includes both Kerr and non-Kerr simulations. We use the exquisite prior constraints on the mass-to-distance ratio for Sgr A* to show that the observed image size is within ∼10% of the Kerr predictions. We use these bounds to constrain metrics that are parametrically different from Kerr, as well as the charges of several known spacetimes. To consider alternatives to the presence of an event horizon, we explore the possibility that Sgr A* is a compact object with a surface that either absorbs and thermally reemits incident radiation or partially reflects it. Using the observed image size and the broadband spectrum of Sgr A*, we conclude that a thermal surface can be ruled out and a fully reflective one is unlikely. We compare our results to the broader landscape of gravitational tests. Together with the bounds found for stellar-mass black holes and the M87 black hole, our observations provide further support that the external spacetimes of all black holes are described by the Kerr metric, independent of their mass
The Event Horizon Telescope image of the Quasar NRAO 530
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 Sagittarius A*. At z=0.902, this is the most
distant object imaged by the EHT so far. We reconstruct the first images of the source at 230 GHz, at an unprecedented
angular resolution of ∼20 μas, both in total intensity and in linear polarization (LP).We do not detect source variability,
allowing us to represent the whole data set with static images. The images reveal a bright feature located on the southern
end of the jet, which we associate with the core. The feature is linearly polarized, with a fractional polarization of ∼5%–
8%, and it has a substructure consisting of two components. Their observed brightness temperature suggests that the
energy density of the jet is dominated by the magnetic field. The jet extends over 60 μas along a position angle∼−28°.
It includes two features with orthogonal directions of polarization (electric vector position angle), parallel and
perpendicular to the jet axis, consistent with a helical structure of the magnetic field in the jet. The outermost feature has
a particularly high degree of LP, suggestive of a nearly uniform magnetic field. Future EHT observations will probe the
variability of the jet structure on microarcsecond scales, while simultaneous multiwavelength monitoring will provide
insight into the high-energy emission origin.ACKNOWLEDGEMENTS : The Event Horizon Telescope Collaboration thanks the
following organizations and programs: the Academia Sinica;
the Academy of Finland (projects 274477, 284495, 312496,
315721); the Agencia Nacional de Investigación y Desarrollo
(ANID), Chile via NCN19_058 (TITANs) and Fondecyt
1221421, the Alexander von Humboldt Stiftung; an Alfred P.
Sloan Research Fellowship; Allegro, the European ALMA
Regional Centre node in the Netherlands, the NL astronomy
research network NOVA and the astronomy institutes of the
University of Amsterdam, Leiden University and Radboud University; the ALMA North America Development Fund; the
black hole Initiative, which is funded by grants from the John
Templeton Foundation and the Gordon and Betty Moore
Foundation (although the opinions expressed in this work are
those of the author(s) and do not necessarily reflect the views of
these Foundations); Chandra DD7-18089X and TM6-17006X;
the China Scholarship Council; China Postdoctoral Science
Foundation fellowship (2020M671266); Consejo Nacional de
Ciencia y Tecnología (CONACYT, Mexico, projects U0004-
246083, U0004-259839, F0003-272050, M0037-279006,
F0003-281692, 104497, 275201, 263356); the Consejería de
Economía, Conocimiento, Empresas y Universidad of the Junta
de Andalucía (grant P18-FR-1769), the Consejo Superior de
Investigaciones Científicas (grant 2019AEP112); the Delaney
Family via the Delaney Family John A. Wheeler Chair at
Perimeter Institute; Dirección General de Asuntos del Personal
Académico-Universidad Nacional Autónoma de México
(DGAPA-UNAM, projects IN112417 and IN112820); the
Dutch Organization for Scientific Research (NWO) VICI
award (grant 639.043.513) and grant OCENW.KLEIN.113;
the Dutch National Supercomputers, Cartesius and Snellius
(NWO Grant 2021.013); the EACOA Fellowship awarded by
the East Asia Core Observatories Association, which consists
of the Academia Sinica Institute of Astronomy and Astrophysics,
the National Astronomical Observatory of Japan,
Center for Astronomical Mega-Science, Chinese Academy of
Sciences, and the Korea Astronomy and Space Science
Institute; the European Research Council (ERC) Synergy
Grant “BlackHoleCam: Imaging the Event Horizon of Black
Holes” (grant 610058); the European Union Horizon 2020
research and innovation program under grant agreements
RadioNet (No. 730562) and M2FINDERS (No. 101018682);
the Horizon ERC Grants 2021 program under grant agreement
No. 101040021; the Generalitat Valenciana postdoctoral grant
APOSTD/2018/177 and GenT Program (project CIDEGENT/
2018/021); MICINN Research Project PID2019-108995GBC22;
the European Research Council for advanced grant
“JETSET: Launching, propagation and emission of relativistic
jets from binary mergers and across mass scales” (grant No.
884631); the Institute for Advanced Study; the Istituto
Nazionale di Fisica Nucleare (INFN) sezione di Napoli,
iniziative specifiche TEONGRAV; the International Max
Planck Research School for Astronomy and Astrophysics at
the Universities of Bonn and Cologne; DFG research grant “Jet
physics on horizon scales and beyond” (grant No. FR 4069/2-
1); Joint Columbia/Flatiron Postdoctoral Fellowship, research
at the Flatiron Institute is supported by the Simons Foundation;
the Japan Ministry of Education, Culture, Sports, Science and
Technology (MEXT; grant JPMXP1020200109); the Japanese
Government (Monbukagakusho: MEXT) Scholarship; the
Japan Society for the Promotion of Science (JSPS) Grant-in-
Aid for JSPS Research Fellowship (JP17J08829); the Joint
Institute for Computational Fundamental Science, Japan; the
Key Research Program of Frontier Sciences, Chinese Academy
of Sciences (CAS, grants QYZDJ-SSW-SLH057, QYZDJS
SW-SYS008, ZDBS-LY-SLH011); the Leverhulme Trust
Early Career Research Fellowship; the Max-Planck-Gesell
schaft (MPG); the Max Planck Partner Group of the MPG and
the CAS; the MEXT/JSPS KAKENHI (grants 18KK0090,
JP21H01137, JP18H03721, JP18K13594, 18K03709, JP19K1
4761, 18H01245, 25120007); the Malaysian Fundamental
Research Grant Scheme (FRGS) FRGS/1/2019/STG02/
UM/02/6; the MIT International Science and Technology
Initiatives (MISTI) Funds; the Ministry of Science and
Technology (MOST) of Taiwan (103-2119-M-001-010-MY2,
105-2112-M-001-025-MY3, 105-2119-M-001-042, 106-2112-
M-001-011, 106-2119-M-001-013, 106-2119-M-001-027, 106-
2923-M-001-005, 107-2119-M-001-017, 107-2119-M-001-
020, 107-2119-M-001-041, 107-2119-M-110-005, 107-2923-
M-001-009, 108-2112-M-001-048, 108-2112-M-001-051, 108-
2923-M-001-002, 109-2112-M-001-025, 109-2124-M-001-
005, 109-2923-M-001-001, 110-2112-M-003-007-MY2, 110-
2112-M-001-033, 110-2124-M-001-007, and 110-2923-M-
001-001); the Ministry of Education (MoE) of Taiwan Yushan
Young Scholar Program; the Physics Division, National Center
for Theoretical Sciences of Taiwan; the National Aeronautics
and Space Administration (NASA, Fermi Guest Investigator
grants 80NSSC20K1567 and 80NSSC22K1571, NASA Astrophysics
Theory Program grant 80NSSC20K0527, NASA
NuSTAR award 80NSSC20K0645); NASA Hubble Fellowship
grants HST-HF2-51431.001-A, HST-HF2-51482.001-A
awarded by the Space Telescope Science Institute, which is
operated by the Association of Universities for Research in
Astronomy, Inc., for NASA, under contract NAS5-26555; the
National Institute of Natural Sciences (NINS) of Japan; the
National Key Research and Development Program of China
(grant 2016YFA0400704, 2017YFA0402703, 2016YFA040
0702); the National Science Foundation (NSF, grants AST-
0096454, AST-0352953, AST-0521233, AST-0705062, AST-
0905844, AST-0922984, AST-1126433, AST-1140030, DGE-
1144085, AST-1207704, AST-1207730, AST-1207752, MRI-
1228509, OPP-1248097, AST-1310896, AST-1440254, AST-
1555365, AST-1614868, AST-1615796, AST-1715061, AST-
1716327, AST-1716536, OISE-1743747, AST-1816420, AST-
1935980, AST-2034306); NSF Astronomy and Astrophysics
Postdoctoral Fellowship (AST-1903847); the Natural Science
Foundation of China (grants 11650110427, 10625314,
11721303, 11725312, 11873028, 11933007, 11991052, 119910
53, 12192220, 12192223); the Natural Sciences and Engineering
Research Council of Canada (NSERC, including a
Discovery grant and the NSERC Alexander Graham Bell
Canada Graduate Scholarships-Doctoral Program); the National
Youth Thousand Talents Program of China; the National
Research Foundation of Korea (the Global PhD Fellowship
grant: grants NRF-2015H1A2A1033752, the Korea Research
Fellowship Program: NRF-2015H1D3A1066561, Brain
Pool Program: 2019H1D3A1A01102564, Basic Research
Support grant 2019R1F1A1059721, 2021R1A6A3A01086420,
2022R1C1C1005255); Netherlands Research School for
Astronomy (NOVA) Virtual Institute of Accretion (VIA)
postdoctoral fellowships; Onsala Space Observatory (OSO)
national infrastructure, for the provisioning of its facilities/
observational support (OSO receives funding through the
Swedish Research Council under grant 2017-00648); the
Perimeter Institute for Theoretical Physics (research at Perimeter
Institute is supported by the Government of Canada through the
Department of Innovation, Science and Economic Development
and by the Province of Ontario through the Ministry of
Research, Innovation and Science); the Princeton Gravity
Initiative; the Spanish Ministerio de Ciencia e Innovación
(grants PGC2018-098915-B-C21, AYA2016-80889-P, PID
2019-108995GB-C21, PID2020-117404GB-C21); the University
of Pretoria for financial aid in the provision of the new
Cluster Server nodes and SuperMicro (USA) for a SEEDING grant approved toward these nodes in 2020; the Shanghai Pilot
Program for Basic Research, Chinese Academy of Science,
Shanghai Branch (JCYJ-SHFY-2021-013); the State Agency for
Research of the Spanish MCIU through the “Center of
Excellence Severo Ochoa” award for the Instituto de Astrofísica
de Andalucía (SEV-2017-0709); the Spinoza Prize SPI 78-409;
the South African Research Chairs Initiative, through the South
African Radio Astronomy Observatory (SARAO, grant ID
77948), which is a facility of the National Research Foundation
(NRF), an agency of the Department of Science and Innovation
(DSI) of South Africa; the Toray Science Foundation; the
Swedish Research Council (VR); the US Department of Energy
(USDOE) through the Los Alamos National Laboratory
(operated by Triad National Security, LLC, for the National
Nuclear Security Administration of the USDOE (Contract
89233218CNA000001); and the YCAA Prize Postdoctoral
Fellowship.
We thank the staff at the participating observatories,
correlation centers, and institutions for their enthusiastic
support. This paper makes use of the following ALMA data:
ADS/JAO.ALMA#2016.1.01154.V. ALMA is a partnership
of the European Southern Observatory (ESO; Europe,
representing its member states), NSF, and National Institutes
of Natural Sciences of Japan, together with National Research
Council (Canada), Ministry of Science and Technology
(MOST; Taiwan), Academia Sinica Institute of Astronomy
and Astrophysics (ASIAA; Taiwan), and Korea Astronomy and
Space Science Institute (KASI; Republic of Korea), in
cooperation with the Republic of Chile. The Joint ALMA
Observatory is operated by ESO, Associated Universities, Inc.
(AUI)/NRAO, and the National Astronomical Observatory of
Japan (NAOJ). The NRAO is a facility of the NSF operated
under cooperative agreement by AUI. This research used
resources of the Oak Ridge Leadership Computing Facility at
the Oak Ridge National Laboratory, which is supported by the
Office of Science of the U.S. Department of Energy under
contract No. DE-AC05-00OR22725. We also thank the Center
for Computational Astrophysics, National Astronomical Observatory
of Japan. The computing cluster of Shanghai VLBI
correlator supported by the Special Fund for Astronomy from
the Ministry of Finance in China is acknowledged. This work
was supported by FAPESP (Fundacao de Amparo a Pesquisa
do Estado de Sao Paulo) under grant 2021/01183-8.
APEX is a collaboration between the Max-Planck-Institut für
Radioastronomie (Germany), ESO, and the Onsala Space
Observatory (Sweden). The SMA is a joint project between the
SAO and ASIAA and is funded by the Smithsonian Institution
and the Academia Sinica. The JCMT is operated by the East
Asian Observatory on behalf of the NAOJ, ASIAA, and KASI,
as well as the Ministry of Finance of China, Chinese Academy
of Sciences, and the National Key Research and Development
Program (No. 2017YFA0402700) of China and Natural
Science Foundation of China grant 11873028. Additional
funding support for the JCMT is provided by the Science and
Technologies Facility Council (UK) and participating universities
in the UK and Canada. The LMT is a project operated
by the Instituto Nacional de Astrófisica, Óptica, y Electrónica
(Mexico) and the University of Massachusetts at Amherst
(USA). The IRAM 30 m telescope on Pico Veleta, Spain is
operated by IRAM and supported by CNRS (Centre National
de la Recherche Scientifique, France), MPG (Max-Planck-
Gesellschaft, Germany) and IGN (Instituto Geográfico
Nacional, Spain). The SMT is operated by the Arizona Radio
Observatory, a part of the Steward Observatory of the
University of Arizona, with financial support of operations
from the State of Arizona and financial support for instrumentation
development from the NSF. Support for SPT participation
in the EHT is provided by the National Science Foundation
through award OPP-1852617 to the University of Chicago.
Partial support is also provided by the Kavli Institute of
Cosmological Physics at the University of Chicago. The SPT
hydrogen maser was provided on loan from the GLT, courtesy
of ASIAA.
This work used the Extreme Science and Engineering
Discovery Environment (XSEDE), supported by NSF grant
ACI-1548562, and CyVerse, supported by NSF grants DBI-
0735191, DBI-1265383, and DBI-1743442. XSEDE Stampede2
resource at TACC was allocated through TGAST170024
and TG-AST080026N. XSEDE JetStream
resource at PTI and TACC was allocated through
AST170028. This research is part of the Frontera computing
project at the Texas Advanced Computing Center through the
Frontera Large-Scale Community Partnerships allocation
AST20023. Frontera is made possible by National Science
Foundation award OAC-1818253. This research was carried
out using resources provided by the Open Science Grid, which
is supported by the National Science Foundation and the U.S.
Department of Energy Office of Science. Additional work used
ABACUS2.0, which is part of the eScience center at Southern
Denmark University. Simulations were also performed on the
SuperMUC cluster at the LRZ in Garching, on the LOEWE
cluster in CSC in Frankfurt, on the HazelHen cluster at the
HLRS in Stuttgart, and on the Pi2.0 and Siyuan Mark-I at
Shanghai Jiao Tong University. The computer resources of the
Finnish IT Center for Science (CSC) and the Finnish
Computing Competence Infrastructure (FCCI) project are
acknowledged. This research was enabled in part by support
provided by Compute Ontario (http://computeontario.ca),
Calcul Quebec (http://www.calculquebec.ca), and Compute
Canada (http://www.computecanada.ca).
The EHTC has received generous donations of FPGA chips
from Xilinx Inc., under the Xilinx University Program. The
EHTC has benefited from technology shared under open-source
license by the Collaboration for Astronomy Signal Processing
and Electronics Research (CASPER). The EHT project is
grateful to T4Science and Microsemi for their assistance with
Hydrogen Masers. This research has made use of NASA’s
Astrophysics Data System. We gratefully acknowledge the
support provided by the extended staff of the ALMA, both from
the inception of the ALMA Phasing Project through the
observational campaigns of 2017 and 2018. We would like to
thank A. Deller and W. Brisken for EHT-specific support with
the use of DiFX. We thank Martin Shepherd for the addition of
extra features in the Difmap software that were used for the
CLEAN imaging results presented in this paper. We acknowledge
the significance and cultural reverance that Maunakea,
where the SMA and JCMT EHT stations are located, has always
held within the indigenous Hawaiian people.
SOFTWARE : DIFMAP (Shepherd 1997), Matplotlib
(Hunter 2007), DiFX (Deller et al. 2011), NumPy (van der
Walt et al. 2011), eht-imaging (Chael et al. 2016),
PolConvert (Martí-Vidal et al. 2016), SMILI (Akiyama
et al. 2017), EHT-HOPS (Blackburn et al. 2019), Themis
(Broderick et al. 2020a), DMC (Pesce 2021).https://iopscience.iop.org/journal/0004-637Xam2024PhysicsNon
First M87 Event Horizon Telescope Results. IX. Detection of Near-horizon Circular Polarization
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 polarization have further identified a coherent spiral pattern around the black hole, produced from ordered magnetic fields threading the emitting plasma. Here we present the first analysis of circular polarization using EHT data, acquired in 2017, which can potentially provide additional insights into the magnetic fields and plasma composition near the black hole. Interferometric closure quantities provide convincing evidence for the presence of circularly polarized emission on event-horizon scales. We produce images of the circular polarization using both traditional and newly developed methods. All methods find a moderate level of resolved circular polarization across the image (〈∣v∣〉 < 3.7%), consistent with the low image-integrated circular polarization fraction measured by the Atacama Large Millimeter/submillimeter Array (∣v int∣ < 1%). Despite this broad agreement, the methods show substantial variation in the morphology of the circularly polarized emission, indicating that our conclusions are strongly dependent on the imaging assumptions because of the limited baseline coverage, uncertain telescope gain calibration, and weakly polarized signal. We include this upper limit in an updated comparison to general relativistic magnetohydrodynamic simulation models. This analysis reinforces the previously reported preference for magnetically arrested accretion flow models. We find that most simulations naturally produce a low level of circular polarization consistent with our upper limit and that Faraday conversion is likely the dominant production mechanism for circular polarization at 230 GHz in M87*
Ordered magnetic fields around the 3C 84 central black hole
Please read abstract in article.http://www.hanspub.org/Journal/AAS.htmlPhysicsNon
First Sagittarius A* Event Horizon Telescope Results. VII. Polarization of the Ring
The Event Horizon Telescope observed the horizon-scale synchrotron emission region around the Galactic center supermassive black hole, Sagittarius A* (Sgr A*), in 2017. These observations revealed a bright, thick ring morphology with a diameter of 51.8 ± 2.3 μas and modest azimuthal brightness asymmetry, consistent with the expected appearance of a black hole with mass M ≈ 4 × 106 M ⊙. From these observations, we present the first resolved linear and circular polarimetric images of Sgr A*. The linear polarization images demonstrate that the emission ring is highly polarized, exhibiting a prominent spiral electric vector polarization angle pattern with a peak fractional polarization of ∼40% in the western portion of the ring. The circular polarization images feature a modestly (∼5%–10%) polarized dipole structure along the emission ring, with negative circular polarization in the western region and positive circular polarization in the eastern region, although our methods exhibit stronger disagreement than for linear polarization. We analyze the data using multiple independent imaging and modeling methods, each of which is validated using a standardized suite of synthetic data sets. While the detailed spatial distribution of the linear polarization along the ring remains uncertain owing to the intrinsic variability of the source, the spiraling polarization structure is robust to methodological choices. The degree and orientation of the linear polarization provide stringent constraints for the black hole and its surrounding magnetic fields, which we discuss in an accompanying publication
A search for pulsars around Sgr A* in the first Event Horizon Telescope data set
In 2017 the Event Horizon Telescope (EHT) observed the supermassive black hole at the center of the Milky Way,
Sagittarius A* (Sgr A*), at a frequency of 228.1 GHz (λ = 1.3 mm). The fundamental physics tests that even a
single pulsar orbiting Sgr A* would enable motivate searching for pulsars in EHT data sets. The high observing
frequency means that pulsars—which typically exhibit steep emission spectra—are expected to be very faint.
However, it also negates pulse scattering, an effect that could hinder pulsar detections in the Galactic center.
Additionally, magnetars or a secondary inverse Compton emission could be stronger at millimeter wavelengths
than at lower frequencies. We present a search for pulsars close to Sgr A* using the data from the three most
sensitive stations in the EHT 2017 campaign: the Atacama Large Millimeter/submillimeter Array, the Large
Millimeter Telescope, and the IRAM 30 m Telescope. We apply three detection methods based on Fourier-domain
analysis, the fast folding algorithm, and single-pulse searches targeting both pulsars and burst-like transient
emission. We use the simultaneity of the observations to confirm potential candidates. No new pulsars or
significant bursts were found. Being the first pulsar search ever carried out at such high radio frequencies, we detail
our analysis methods and give a detailed estimation of the sensitivity of the search. We conclude that the EHT 2017
observations are only sensitive to a small fraction (2.2%) of the pulsars that may exist close to Sgr A*, motivating
further searches for fainter pulsars in the region.ACKNOWLEDGEMENTS : We are grateful to the anonymous referee for the review and
providing suggestions that improved the manuscript. We thank the
staff at the participating observatories and correlator centers that
made possible the EHT 2017 observations. P.T. thanks Pablo
Mellado and William Robertson for their support through several
stages of the data reduction in the IRAM servers. R.P.E. is funded by the Chinese Academy of Sciences President’s International
Fellowship Initiative, grant No. 2021FSM0004. S.M.R. is a
CIFAR Fellow and is supported by the NSF Physics Frontiers
Center awards 1430284 and 2020265. This work was supported
by the European Research Council Synergy Grant “Black-
HoleCam: Imaging the Event Horizon of Black Holes” (grant
610058). This paper makes use of the following ALMA data:
ADS/JAO.ALMA#2016.1.01404.V. ALMA is a partnership of
the European Southern Observatory (ESO; Europe, representing its
member states), NSF, and National Institutes of Natural Sciences
of Japan, together with National Research Council (Canada),
Ministry of Science and Technology (MOST; Taiwan), Academia
Sinica Institute of Astronomy and Astrophysics (ASIAA; Taiwan),
and Korea Astronomy and Space Science Institute (KASI;
Republic of Korea), in cooperation with the Republic of Chile.
The Joint ALMA Observatory is operated by ESO, Associated
Universities, Inc. (AUI)/NRAO, and the National Astronomical
Observatory of Japan (NAOJ). The National Radio Astronomy
Observatory is a facility of the National Science Foundation
operated under cooperative agreement by Associated Universities,
Inc. The LMT is a project operated by the Instituto Nacional de
Astrófisica, Óptica, y Electrónica (Mexico) and the University of
Massachusetts at Amherst (USA). This work is partly based on
observations carried out with the IRAM 30m Telescope under
project No. 084-17. The IRAM 30m Telescope on Pico Veleta,
Spain is operated by IRAM and supported by CNRS (Centre
National de la Recherche Scientifique, France), MPG (Max-
Planck-Gesellschaft, Germany), and IGN (Instituto Geográfico
Nacional, Spain). This research has made use of NASA’s
Astrophysics Data System Bibliographic Services. Part of this
research was carried out at the Jet Propulsion Laboratory,
California Institute of Technology, under a contract with the
National Aeronautics and Space Administration. The Event
Horizon Telescope Collaboration thanks the following organizations
and programs: the Academia Sinica; the Academy of Finland
(projects 274477, 284495, 312496, and 315721); the Agencia
Nacional de Investigación y Desarrollo (ANID), Chile via
NCN19_058 (TITANs) and Fondecyt 1221421, the Alexander
von Humboldt Stiftung; an Alfred P. Sloan Research Fellowship;
Allegro, the European ALMA Regional Centre node in the
Netherlands, the NL astronomy research network NOVA and the
astronomy institutes of the University of Amsterdam, Leiden
University and Radboud University; the ALMA North America
Development Fund; the Astrophysics and High Energy Physics
program by MCIN (with funding from European Union
NextGenerationEU, PRTR-C17I1); the Black Hole Initiative,
which is funded by grants from the John Templeton Foundation
and the Gordon and Betty Moore Foundation (although the
opinions expressed in this work are those of the author(s) and do
not necessarily reflect the views of these Foundations); theBrinson
Foundation; Chandra DD7-18089X and TM6-17006X; the China
Scholarship Council; the China Postdoctoral Science Foundation
fellowships (2020M671266, 2022M712084); Consejo Nacional de
Ciencia y Tecnología (CONACYT, Mexico, projects U0004-
246083, U0004-259839, F0003-272050, M0037-279006, F0003-
281692, 104497, 275201, and 263356); the Consejería de
Economía, Conocimiento, Empresas y Universidad of the Junta
de Andalucía (grant P18-FR-1769), the Consejo Superior de
Investigaciones Científicas (grant 2019AEP112); the Delaney
Family via the Delaney Family John A. Wheeler Chair at
Perimeter Institute; Dirección General de Asuntos del Personal
Académico-Universidad Nacional Autónoma de México
(DGAPA-UNAM, projects IN112417 and IN112820); the Dutch
Organization for Scientific Research (NWO) for VICI award (grant
639.043.513), grant OCENW.KLEIN.113 and the Dutch black
hole Consortium (with project No. NWA 1292.19.202) of the
research program the National Science Agenda; the Dutch National
Supercomputers, Cartesius and Snellius (NWO grant 2021.013);
the EACOA Fellowship awarded by the East Asia Core
Observatories Association, which consists of the Academia Sinica
Institute of Astronomy and Astrophysics, the National Astronomical
Observatory of Japan, Center for Astronomical Mega-Science,
Chinese Academy of Sciences, and the Korea Astronomy and
Space Science Institute; the European Union Horizon 2020
research and innovation program under grant agreements RadioNet
(No 730562) and M2FINDERS (No 101018682); the Horizon
ERC Grants 2021 program under grant agreement No. 101040021;
the Generalitat Valenciana (grants APOSTD/2018/177 and
ASFAE/2022/018) and GenT Program (project CIDEGENT/
2018/021); MICINN Research Project PID2019-108995GB-C22;
the European Research Council for advanced grant “JETSET:
Launching, propagation and emission of relativistic jets from
binary mergers and across mass scales” (grant No. 884631); the
Institute for Advanced Study; the Istituto Nazionale di Fisica
Nucleare (INFN) sezione di Napoli, iniziative specifiche TEONGRAV;
the International Max Planck Research School for
Astronomy and Astrophysics at the Universities of Bonn and
Cologne; DFG research grant “Jet physics on horizon scales and
beyond” (grant No. FR 4069/2-1); Joint Columbia/Flatiron
Postdoctoral Fellowship, research at the Flatiron Institute is
supported by the Simons Foundation; the Japan Ministry of
Education, Culture, Sports, Science and Technology (MEXT;
grant JPMXP1020200109); the Japan Society for the Promotion of
Science (JSPS) Grant-in-Aid for JSPS Research Fellowship
(JP17J08829); the Joint Institute for Computational Fundamental
Science, Japan; the Key Research Program of Frontier Sciences,
Chinese Academy of Sciences (CAS, grants QYZDJ-SSWSLH057,
QYZDJSSW-SYS008, ZDBS-LY-SLH011); the Leverhulme
Trust Early Career Research Fellowship; the Max-Planck-
Gesellschaft (MPG); the Max Planck Partner Group of the MPG
and the CAS; the MEXT/JSPS KAKENHI (grants 18KK0090,
JP21H01137, JP18H03721, JP18K13594, 18K03709,
JP19K14761, 18H01245, 25120007); the Malaysian Fundamental
Research Grant Scheme (FRGS) FRGS/1/2019/STG02/UM/
02/6; the MIT International Science and Technology Initiatives
(MISTI) Funds; the Ministry of Science and Technology (MOST)
of Taiwan (103-2119-M-001-010-MY2, 105-2112-M-001-025-
MY3, 105-2119-M-001-042, 106-2112-M-001-011, 106-2119-M-
001-013, 106-2119-M-001-027, 106-2923-M-001-005, 107-2119-
M-001-017, 107-2119-M-001-020, 107-2119-M-001-041, 107-
2119-M-110-005, 107-2923-M-001-009, 108-2112-M-001-048,
108-2112-M-001-051, 108-2923-M-001-002, 109-2112-M-001-
025, 109-2124-M-001-005, 109-2923-M-001-001, 110-2112-M-
003-007-MY2, 110-2112-M-001-033, 110-2124-M-001-007, and
110-2923-M-001-001); the Ministry of Education (MoE) of
Taiwan Yushan Young Scholar Program; the Physics Division,
National Center for Theoretical Sciences of Taiwan; the National
Aeronautics and Space Administration (NASA, Fermi Guest
Investigator grant 80NSSC20K1567, NASA Astrophysics Theory
Program grant 80NSSC20K0527, NASA NuSTAR award
80NSSC20K0645); NASA Hubble Fellowship grants HST-HF2-
51431.001-A, HST-HF2-51482.001-A awarded by the Space
Telescope Science Institute, which is operated by the
Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555; the National Institute of
Natural Sciences (NINS) of Japan; the National Key Research and
Development Program of China (grant 2016YFA0400704,
2017YFA0402703, 2016YFA0400702); the National Science
Foundation (NSF, grants AST-0096454, AST-0352953, AST-
0521233, AST-0705062, AST-0905844, AST-0922984, AST-
1126433, AST-1140030, DGE-1144085, AST-1207704, AST-
1207730, AST-1207752, MRI-1228509, OPP-1248097, AST-
1310896, AST-1440254, AST-1555365, AST-1614868, AST-
1615796, AST-1715061, AST-1716327, AST-1716536, OISE-
1743747, AST-1816420, AST-1935980, AST-2034306); NSF
Astronomy and Astrophysics Postdoctoral Fellowship (AST-
1903847); the Natural Science Foundation of China (grants
11650110427, 10625314, 11721303, 11725312, 11873028,
11933007, 11991052, 11991053, 12192220, 12192223); the
Natural Sciences and Engineering Research Council of Canada
(NSERC, including a Discovery Grant and the NSERC Alexander
Graham Bell Canada Graduate Scholarships-Doctoral Program);
the National Youth Thousand Talents Program of China; the
National Research Foundation of Korea (the Global PhD
Fellowship Grant: grants NRF-2015H1A2A1033752, the Korea
Research Fellowship Program: NRF-2015H1D3A1066561, Brain
Pool Program: 2019H1D3A1A01102564, Basic Research
Support Grant 2019R1F1A1059721, 2021R1A6A3A01086420,
2022R1C1C1005255); Netherlands Research School for Astronomy
(NOVA) Virtual Institute of Accretion (VIA) postdoctoral
fellowships; Onsala Space Observatory (OSO) national infrastructure,
for the provisioning of its facilities/observational support
(OSO receives funding through the Swedish Research Council
under grant 2017-00648); the Perimeter Institute for Theoretical
Physics (research at Perimeter Institute is supported by the
Government of Canada through the Department of Innovation,
Science and Economic Development and by the Province of
Ontario through the Ministry of Research, Innovation and
Science); the Princeton Gravity Initiative; the Spanish Ministerio
de Ciencia e Innovación (grants PGC2018-098915-B-C21,
AYA2016-80889-P, PID2019-108995GB-C21, and PID2020-
117404GB-C21); the University of Pretoria for financial aid in
the provision of the new Cluster Server nodes and SuperMicro
(USA) for an SEEDING grant approved toward these nodes in
2020; the Shanghai Pilot Program for Basic Research, Chinese
Academy of Science, Shanghai Branch (JCYJ-SHFY-2021-013);
the State Agency for Research of the Spanish MCIU through the
“Center of Excellence Severo Ochoa” award for the Instituto de
Astrofísica de Andalucía (SEV-2017-0709); the Spinoza Prize SPI
78-409; the South African Research Chairs Initiative, through the
South African Radio Astronomy Observatory (SARAO, grant ID
77948), which is a facility of the National Research Foundation
(NRF), an agency of the Department of Science and Innovation
(DSI) of South Africa; the Toray Science Foundation; the Swedish
Research Council (VR); the US Department of Energy (USDOE)
through the Los Alamos National Laboratory (operated by Triad
National Security, LLC, for the National Nuclear Security
Administration of the USDOE (contract 89233218CNA000001);
and the YCAA Prize Postdoctoral Fellowship. This research used
resources of the Oak Ridge Leadership Computing Facility at the
Oak Ridge National Laboratory, which is supported by the Office
of Science of the U.S. Department of Energy under contract No.
DE-AC05-00OR22725. We also thank the Center for Computational
Astrophysics, National Astronomical Observatory of Japan.
The computing cluster of Shanghai VLBI correlator supported by
the Special Fund for Astronomy from the Ministry of Finance in
China is acknowledged. This work was partially supported by
FAPESP (Fundação de Amparo á Pesquisa do Estado de São
Paulo) under grant 2021/01183-8. APEX is a collaboration
between the Max-Planck-Institut für Radioastronomie (Germany),
ESO, and the Onsala Space Observatory (Sweden). The SMT is
operated by the Arizona Radio Observatory, a part of the Steward
Observatory of the University of Arizona, with financial support of
operations from the State of Arizona and financial support for
instrumentation development from the NSF. Support for SPT
participation in the EHT is provided by the National Science
Foundation through award OPP-1852617 to the University of
Chicago. Partial support is also provided by the Kavli Institute of
Cosmological Physics at the University of Chicago. The SPT
hydrogen maser was provided on loan from the GLT, courtesy of
ASIAA. The SMA is a joint project between the SAO and ASIAA
and is funded by the Smithsonian Institution and the Academia
Sinica. The JCMT is operated by the East Asian Observatory on
behalf of the NAOJ, ASIAA, and KASI, as well as the Ministry of
Finance of China, Chinese Academy of Sciences, and the
National Key Research and Development Program (No.
2017YFA0402700) of China and Natural Science Foundation of
China grant 11873028. Additional funding support for the JCMT
is provided by the Science and Technologies Facility Council
(UK) and participating universities in the UK and Canada. We
acknowledge the significance that Maunakea, where the SMA and
JCMT EHT stations are located, has for the indigenous Hawaiian people. The EHTC has received generous donations of FPGA
chips from Xilinx Inc., under the Xilinx University Program. The
EHTC has benefited from technology shared under an open-source
license by the Collaboration for Astronomy Signal Processing and
Electronics Research (CASPER). The EHT project is grateful to
T4Science and Microsemi for their assistance with Hydrogen
Masers. We gratefully acknowledge the support provided by the
extended staff of the ALMA, both from the inception of the
ALMA Phasing Project through the observational campaigns of
2017 and 2018. We would like to thank A. Deller and W. Brisken
for EHT-specific support with the use of DiFX.
FACILITIES: ALMA, LMT, IRAM:30m.
SOFTWARE : MPIvdif2psrfits, PRESTO (Ransom 2011),
RIPTIDE (Morello et al. 2020), NUMPY (Harris et al. 2020),
SCIPY (Virtanen et al. 2020), MATPLOTLIB (Hunter 2007),
TEMPO (Nice et al. 2015), SIGPYPROC (Lorimer 2011).https://iopscience.iop.org/journal/0004-637Xam2024PhysicsNon