Nuclear Physics Multimessenger Astrophysics Constraints on the Neutron Star Equation of State: Adding NICER's PSR J0740+6620 Measurement

In the past few years, new observations of neutron stars (NSs) and NS mergers have provided a wealth of data that allow one to constrain the equation of state (EOS) of nuclear matter at densities above nuclear saturation density. However, most observations were based on NSs with masses of about 1.4 M⊙, probing densities up to ∼three to four times the nuclear saturation density. Even higher densities are probed inside massive NSs such as PSR J0740+6620. Very recently, new radio observations provided an update to the mass estimate for PSR J0740+6620, and X-ray observations by the NICER and XMM telescopes constrained its radius. Based on these new measurements, we revisit our previous nuclear physics multimessenger astrophysics constraints and derive updated constraints on the EOS describing the NS interior. By combining astrophysical observations of two radio pulsars, two NICER measurements, the two gravitational-wave detections GW170817 and GW190425, detailed modeling of the kilonova AT 2017gfo, and the gamma-ray burst GRB 170817A, we are able to estimate the radius of a typical 1.4 M⊙ NS to be 11.94-0.87+0.76 km at 90% confidence. Our analysis allows us to revisit the upper bound on the maximum mass of NSs and disfavors the presence of a strong first-order phase transition from nuclear matter to exotic forms of matter, such as quark matter, inside NSs

Measuring HERA's Primary Beam in Situ: Methodology and First Results

The central challenge in 21 cm cosmology is isolating the cosmological signal from bright foregrounds. Many separation techniques rely on the accurate knowledge of the sky and the instrumental response, including the antenna primary beam. For drift-scan telescopes, such as the Hydrogen Epoch of Reionization Array (HERA), that do not move, primary beam characterization is particularly challenging because standard beam-calibration routines do not apply (Cornwell et al.) and current techniques require accurate source catalogs at the telescope resolution. We present an extension of the method from Pober et al. where they use beam symmetries to create a network of overlapping source tracks that break the degeneracy between source flux density and beam response and allow their simultaneous estimation. We fit the beam response of our instrument using early HERA observations and find that our results agree well with electromagnetic simulations down to a -20 dB level in power relative to peak gain for sources with high signal-to-noise ratio. In addition, we construct a source catalog with 90 sources down to a flux density of 1.4 Jy at 151 MHz.The central challenge in 21 cm cosmology is isolating the cosmological signal from bright foregrounds. Many separation techniques rely on the accurate knowledge of the sky and the instrumental response, including the antenna primary beam. For drift-scan telescopes, such as the Hydrogen Epoch of Reionization Array (HERA), that do not move, primary beam characterization is particularly challenging because standard beam-calibration routines do not apply (Cornwell et al.) and current techniques require accurate source catalogs at the telescope resolution. We present an extension of the method from Pober et al. where they use beam symmetries to create a network of overlapping source tracks that break the degeneracy between source flux density and beam response and allow their simultaneous estimation. We fit the beam response of our instrument using early HERA observations and find that our results agree well with electromagnetic simulations down to a -20 dB level in power relative to peak gain for sources with high signal-to-noise ratio. In addition, we construct a source catalog with 90 sources down to a flux density of 1.4 Jy at 151 MHz

Feedback Communication Systems with Limitations on Incremental Redundancy

This paper explores feedback systems using incremental redundancy (IR) with noiseless transmitter confirmation (NTC). For IR-NTC systems based on {\em finite-length} codes (with blocklength $N$) and decoding attempts only at {\em certain specified decoding times}, this paper presents the asymptotic expansion achieved by random coding, provides rate-compatible sphere-packing (RCSP) performance approximations, and presents simulation results of tail-biting convolutional codes. The information-theoretic analysis shows that values of $N$ relatively close to the expected latency yield the same random-coding achievability expansion as with $N = \infty$. However, the penalty introduced in the expansion by limiting decoding times is linear in the interval between decoding times. For binary symmetric channels, the RCSP approximation provides an efficiently-computed approximation of performance that shows excellent agreement with a family of rate-compatible, tail-biting convolutional codes in the short-latency regime. For the additive white Gaussian noise channel, bounded-distance decoding simplifies the computation of the marginal RCSP approximation and produces similar results as analysis based on maximum-likelihood decoding for latencies greater than 200. The efficiency of the marginal RCSP approximation facilitates optimization of the lengths of incremental transmissions when the number of incremental transmissions is constrained to be small or the length of the incremental transmissions is constrained to be uniform after the first transmission. Finally, an RCSP-based decoding error trajectory is introduced that provides target error rates for the design of rate-compatible code families for use in feedback communication systems.Comment: 23 pages, 15 figure

Galaxy Cluster Pressure Profiles as Determined by Sunyaev Zel’dovich Effect Observations with MUSTANG and Bolocam. II. Joint Analysis of 14 Clusters

We present pressure profiles of galaxy clusters determined from high resolution Sunyaev-Zel'dovich (SZ) effect observations of fourteen clusters, which span the redshift range $0.25 < z < 0.89$. The procedure simultaneously fits spherical cluster models to MUSTANG and Bolocam data. In this analysis, we adopt the generalized NFW parameterization of pressure profiles to produce our models. Our constraints on ensemble-average pressure profile parameters, in this study $\gamma$, $C_{500}$, and $P_0$, are consistent with those in previous studies, but for individual clusters we find discrepancies with the X-ray derived pressure profiles from the ACCEPT2 database. We investigate potential sources of these discrepancies, especially cluster geometry, electron temperature of the intracluster medium, and substructure. We find that the ensemble mean profile for all clusters in our sample is described by the parameters: $[\gamma,C_{500},P_0] = [0.3_{-0.1}^{+0.1}, 1.3_{-0.1}^{+0.1}, 8.6_{-2.4}^{+2.4}]$, for cool core clusters: $[\gamma,C_{500},P_0] = [0.6_{-0.1}^{+0.1}, 0.9_{-0.1}^{+0.1}, 3.6_{-1.5}^{+1.5}]$, and for disturbed clusters: $[\gamma,C_{500},P_0] = [0.0_{-0.0}^{+0.1}, 1.5_{-0.2}^{+0.1},13.8_{-1.6}^{+1.6}]$. Four of the fourteen clusters have clear substructure in our SZ observations, while an additional two clusters exhibit potential substructure.Comment: 22 pages, 9 figures, accepted to Ap

First M87 Event Horizon Telescope Results. IV. Imaging the Central Supermassive Black Hole

We present the first Event Horizon Telescope (EHT) images of M87, using observations from April 2017 at 1.3 mm wavelength. These images show a prominent ring with a diameter of similar to 40 mu as, consistent with the size and shape of the lensed photon orbit encircling the "shadow" of a supermassive black hole. The ring is persistent across four observing nights and shows enhanced brightness in the south. To assess the reliability of these results, we implemented a two-stage imaging procedure. In the first stage, four teams, each blind to the others' work, produced images of M87 using both an established method (CLEAN) and a newer technique (regularized maximum likelihood). This stage allowed us to avoid shared human bias and to assess common features among independent reconstructions. In the second stage, we reconstructed synthetic data from a large survey of imaging parameters and then compared the results with the corresponding ground truth images. This stage allowed us to select parameters objectively to use when reconstructing images of M87. Across all tests in both stages, the ring diameter and asymmetry remained stable, insensitive to the choice of imaging technique. We describe the EHT imaging procedures, the primary image features in M87, and the dependence of these features on imaging assumptions.Academy of Finland [274477, 284495, 312496]; European Commission Framework Programme Horizon 2020 Research and Innovation action [731016]; Black Hole Initiative at Harvard University through John Templeton Foundation [60477]; Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT, Chile) [PIA ACT172033, Fondecyt 1171506, BASAL AFB-170002, ALMA-conicyt 31140007]; Consejo Nacional de Ciencia y Tecnologia (CONACYT, Mexico) [104497, 275201, 279006, 281692]; Direccion General de Asuntos del Personal Academico-Universidad Nacional Autonoma de Mexico (DGAPA-UNAM) [IN112417]; European Research Council Synergy Grant "BlackHoleCam: Imaging the Event Horizon of Black Holes" [610058]; Generalitat Valenciana postdoctoral grant [APOSTD/2018/177]; Gordon and Betty Moore Foundation [GBMF 947, GBMF-3561, GBMF-5278]; Japanese Government (Monbukagakusho: MEXT) Scholarship; Japan Society for the Promotion of Science (JSPS) [JP17J08829]; JSPS Overseas Research Fellowships; Key Research Program of Frontier Sciences, Chinese Academy of Sciences (CAS) [QYZDJ-SSW-SLH057, QYZDJ-SSW-SYS008]; Leverhulme Trust Early Career Research Fellowship; MEXT/JSPS KAKENHI [18KK0090, JP18K13594, JP18K03656, JP18H03721, 18K03709, 18H01245, 25120007]; MIT International Science and Technology Initiatives (MISTI) Funds; Ministry of Science and Technology (MOST) of Taiwan [105-2112-M-001-025-MY3, 106-2112-M-001-011, 106-2119-M-001-027, 107-2119-M-001-017, 107-2119-M-001-020, 107-2119-M-110-005]; National Aeronautics and Space Administration (NASA) [80NSSC17K0649]; National Key Research and Development Program of China [2016YFA0400704, 2016YFA0400702]; National Science Foundation (NSF) [AST-0096454, AST-0352953, AST-0521233, AST-0705062, AST-0905844, AST-0922984, AST-1126433, AST-1140030, DGE-1144085]; Natural Science Foundation of China [11573051, 11633006, 11650110427, 10625314, 11721303, 11725312, 11873028, 11873073, U1531245, 11473010]; Natural Sciences and Engineering Research Council of Canada (NSERC); National Research Foundation of Korea [2015-R1D1A1A01056807, NRF-2015H1A2A1033752, NRF-2015H1D3A1066561]; Netherlands Organization for Scientific Research (NWO) VICI award [639.043.513]; Spinoza Prize [SPI 78-409]; Swedish Research Council [2017-00648]; Government of Canada through the Department of Innovation, Science and Economic Development Canada; Province of Ontario through the Ministry of Economic Development, Job Creation and Trade; Russian Science Foundation [17-12-01029]; Spanish Ministerio de Economia y Competitividad [AYA2015-63939-C2-1-P, AYA2016-80889-P]; US Department of Energy (USDOE) through the Los Alamos National Laboratory [89233218CNA000001]; Italian Ministero dell'Istruzione Universita e Ricerca through the grant Progetti Premiali 2012-iALMA [CUP C52I13000140001]; ALMA North America Development Fund; NSF [DBI-0735191, DBI-1265383, DBI-1743442, ACI-1548562]; Smithsonian Institution; Academia Sinica; National Key R&D Program of China [2017YFA0402700]; Science and Technologies Facility Council (UK); CNRS (Centre National de la Recherche Scientifique, France); MPG (Max-Planck-Gesellschaft, Germany); State of Arizona; NSF Physics Frontier Center award [PHY-0114422]; Kavli Foundation; National Science Foundation [PLR-1248097]; NSF Physics Frontier Center [PHY-1125897]; KREONET (Korea Research Environment Open NETwork); Jansky Fellowship program of the National Radio Astronomy Observatory (NRAO); South African Radio Astronomy Observatory (SARAO), which is a facility of the National Research Foundation (NRF), an agency of the Department of Science and Technology (DST) of South Africa; State Agency for Research of the Spanish MCIU through the "Center of Excellence Severo Ochoa" award [SEV-2017-0709]; Compute Ontario; Calcul Quebec; Compute Canada; IGN (Instituto Geografico Nacional, Spain); NSF; GBMF [GBMF-947]; CyVerse; [Chandra TM6-17006X]; [MM07B]; [AST-1207704]; [AST-1207730]; [AST-1207752]; [MRI-1228509]; [OPP-1248097]; [AST-1310896]; [AST-1312651]; [AST-1337663]; [AST-1440254]; [AST-1555365]; [AST-1715061]; [AST-1614868]; [AST-1615796]; [AST-1716327]; [OISE-1743747]; [AST-1816420]This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. 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Size and Shape of Chariklo from Multi-epoch Stellar Occultation

We use data from five stellar occultations observed between 2013 and 2016 to constrain Chariklo’s size and shape, and the ring reflectivity. We consider four possible models for Chariklo (sphere, Maclaurin spheroid, triaxial ellipsoid, and Jacobi ellipsoid), and we use a Bayesian approach to estimate the corresponding parameters. The spherical model has a radius R = 129 ± 3 km. The Maclaurin model has equatorial and polar radii a=b={143}-6+3 {km} and c={96}-4+14 {km}, respectively, with density {970}-180+300 {kg} {{{m}}}-3. The ellipsoidal model has semiaxes a={148}-4+6 {km}, b={132}-5+6 {km}, and c={102}-8+10 {km}. Finally, the Jacobi model has semiaxes a = 157 ± 4 km, b = 139 ± 4 km, and c = 86 ± 1 km, and density {796}-4+2 {kg} {{{m}}}-3. Depending on the model, we obtain topographic features of 6–11 km, typical of Saturn icy satellites with similar size and density. We constrain Chariklo’s geometric albedo between 3.1% (sphere) and 4.9% (ellipsoid), while the ring I/F reflectivity is less constrained between 0.6% (Jacobi) and 8.9% (sphere). The ellipsoid model explains both the optical light curve and the long-term photometry variation of the system, giving a plausible value for the geometric albedo of the ring particles of 10%–15%. The derived mass of Chariklo of 6–8 × 1018 kg places the rings close to 3:1 resonance between the ring mean motion and Chariklo’s rotation period

Roadmap of ultrafast x-ray atomic and molecular physics

X-ray free-electron lasers (XFELs) and table-top sources of x-rays based upon high harmonic generation (HHG) have revolutionized the field of ultrafast x-ray atomic and molecular physics, largely due to an explosive growth in capabilities in the past decade. XFELs now provide unprecedented intensity (1020 W cm−2) of x-rays at wavelengths down to ~1 Ångstrom, and HHG provides unprecedented time resolution (~50 attoseconds) and a correspondingly large coherent bandwidth at longer wavelengths. For context, timescales can be referenced to the Bohr orbital period in hydrogen atom of 150 attoseconds and the hydrogen-molecule vibrational period of 8 femtoseconds; wavelength scales can be referenced to the chemically significant carbon K-edge at a photon energy of ~280 eV (44 Ångstroms) and the bond length in methane of ~1 Ångstrom. With these modern x-ray sources one now has the ability to focus on individual atoms, even when embedded in a complex molecule, and view electronic and nuclear motion on their intrinsic scales (attoseconds and Ångstroms). These sources have enabled coherent diffractive imaging, where one can image non-crystalline objects in three dimensions on ultrafast timescales, potentially with atomic resolution. The unprecedented intensity available with XFELs has opened new fields of multiphoton and nonlinear x-ray physics where behavior of matter under extreme conditions can be explored. The unprecedented time resolution and pulse synchronization provided by HHG sources has kindled fundamental investigations of time delays in photoionization, charge migration in molecules, and dynamics near conical intersections that are foundational to AMO physics and chemistry. This roadmap coincides with the year when three new XFEL facilities, operating at Ångstrom wavelengths, opened for users (European XFEL, Swiss-FEL and PAL-FEL in Korea) almost doubling the present worldwide number of XFELs, and documents the remarkable progress in HHG capabilities since its discovery roughly 30 years ago, showcasing experiments in AMO physics and other applications. Here we capture the perspectives of 17 leading groups and organize the contributions into four categories: ultrafast molecular dynamics, multidimensional x-ray spectroscopies; high-intensity x-ray phenomena; attosecond x-ray science