Table of contents

We present the redshift evolution of the galaxy effective radius r_e obtained from the Hubble Space Telescope (HST) samples of ∼190,000 galaxies at z = 0–10. Our HST samples consist of 176,152 photo-z galaxies at z = 0–6 from the 3D-HST+CANDELS catalog and 10,454 Lyman break galaxies (LBGs) at z = 4–10 identified in the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS), HUDF 09/12, and HFF parallel fields, providing the largest data set to date for galaxy size evolution studies. We derive r_e with the same technique over the wide redshift range of z = 0–10, evaluating the optical-to-UV morphological K correction and the selection bias of photo-z galaxies+LBGs as well as the cosmological surface-brightness dimming effect. We find that r_e values at a given luminosity significantly decrease toward high z, regardless of statistics choices (e.g., ${r}_{{\rm{e}}}\propto {(1+z)}^{-1.10\pm 0.06}$ for median). For star-forming galaxies, there is no evolution of the power-law slope of the size–luminosity relation and the median Sérsic index ($n\sim 1.5$). Moreover, the r_e distribution is well represented by log-normal functions whose standard deviation ${\sigma }_{\mathrm{ln}{r}_{{\rm{e}}}}$ does not show significant evolution within the range of ${\sigma }_{\mathrm{ln}{r}_{{\rm{e}}}}\sim 0.45-0.75$. We calculate the stellar-to-halo size ratio from our r_e measurements and the dark-matter halo masses estimated from the abundance-matching study, and we obtain a nearly constant value of ${r}_{{\rm{e}}}/{r}_{\mathrm{vir}}=1.0\%-3.5\%$ at z = 0–8. The combination of the r_e-distribution shape+standard deviation, the constant ${r}_{{\rm{e}}}/{r}_{\mathrm{vir}}$, and $n\sim 1.5$ suggests a picture in which typical high-z star-forming galaxies have disk-like stellar components in a sense of dynamics and morphology over cosmic time of $z\sim 0-6$. If high-z star-forming galaxies are truly dominated by disks, the ${r}_{{\rm{e}}}/{r}_{\mathrm{vir}}$ value and the disk-formation model indicate that the specific angular momentum of the disk normalized by the host halo is ${j}_{{\rm{d}}}/{m}_{{\rm{d}}}\simeq 0.5-1$. These are statistical results for major stellar components of galaxies, and the detailed study of clumpy subcomponents is presented in the paper II.

A set of diffuse interstellar clouds in the inner Galaxy within a few hundred parsecs of the Galactic plane has been observed at an angular resolution of ≈1&farcm;0 combining data from the NRAO Green Bank Telescope and the Very Large Array. At the distance of the clouds, the linear resolution ranges from ∼1.9 to ∼2.8 pc. These clouds have been selected to be somewhat outside of the Galactic plane, and thus are not confused with unrelated emission, but in other respects they are a Galactic population. They are located near the tangent points in the inner Galaxy, and thus at a quantifiable distance: $2.3\leqslant R\leqslant 6.0$ kpc from the Galactic Center and $-1000\leqslant z\leqslant +610$ pc from the Galactic plane. These are the first images of the diffuse neutral H i clouds that may constitute a considerable fraction of the interstellar medium (ISM). Peak H i column densities lie in the range N_{H i} = 0.8–2.9 × 10²⁰ cm⁻². Cloud diameters vary between about 10 and 100 pc, and their H i mass spans the range from less than a hundred to a few thousands M_⊙. The clouds show no morphological consistency of any kind, except that their shapes are highly irregular. One cloud may lie within the hot wind from the nucleus of the Galaxy, and some clouds show evidence of two distinct thermal phases as would be expected from equilibrium models of the ISM.

To better understand the properties of solar active-region filaments, we present a detailed study on the formation and magnetic structures of two active-region filaments in active region NOAA 11884 during a period of four days. It is found that the shearing motion of the opposite magnetic polarities and the rotation of the small sunspots with negative polarity play an important role in the formation of two active-region filaments. During the formation of these two active-region filaments, one foot of the filaments was rooted in a small sunspot with negative polarity. The small sunspot rotated not only around another small sunspot with negative polarity, but also around the center of its umbra. By analyzing the nonlinear force-free field extrapolation using the vector magnetic fields in the photosphere, twisted structures were found in the two active-region filaments prior to their eruptions. These results imply that the magnetic fields were dragged by the shearing motion between opposite magnetic polarities and became more horizontal. The sunspot rotation twisted the horizontal magnetic fields and finally formed the twisted active-region filaments.

We present a sample of 290 24 μm-selected active galactic nuclei (AGNs) mostly at z ∼ 0.3–2.5, within 5.2 ${\mathrm{deg}}^{2}$ distributed as $25\prime \times 25\prime$ fields around each of 30 galaxy clusters in the Local Cluster Substructure Survey. The sample is nearly complete to 1 mJy at 24 μm, and has a rich multiwavelength set of ancillary data; 162 are detected by Herschel. We use spectral templates for AGNs, stellar populations, and infrared (IR) emission by star-forming galaxies to decompose the spectral energy distributions (SEDs) of these AGNs and their host galaxies, and estimate their star formation rates, AGN luminosities, and host galaxy stellar masses. The set of templates is relatively simple: a standard Type-1 quasar template; another for the photospheric output of the stellar population; and a far-infrared star-forming template. For the Type-2 AGN SEDs, we substitute templates including internal obscuration, and some Type-1 objects require a warm component ($T\gtrsim 50$ K). The individually Herschel-detected Type-1 AGNs and a subset of 17 Type-2 AGNs typically have luminosities $\gt {10}^{45}\;\mathrm{ergs}\;{{\rm{s}}}^{-1}$, and supermassive black holes of $\sim 3\times {10}^{8}\;{M}_{\odot }$ emitting at ∼10% of the Eddington rate. We find them in about twice the numbers of AGNs identified in SDSS data in the same fields, i.e., they represent typical high-luminosity AGNs, not an IR-selected minority. These AGNs and their host galaxies are studied further in an accompanying paper.

We present a detailed description of the physical properties of our current census of white dwarfs within 40 pc of the Sun, based on an exhaustive spectroscopic survey of northern hemisphere candidates from the SUPERBLINK proper motion database. Our method for selecting white dwarf candidates is based on a combination of theoretical color–magnitude relations and reduced proper motion diagrams. We reported in an earlier publication the discovery of nearly 200 new white dwarfs, and we present here the discovery of an additional 133 new white dwarfs, among which we identify 96 DA, 3 DB, 24 DC, 3 DQ, and 7 DZ stars. We further identify 178 white dwarfs that lie within 40 pc of the Sun, representing a 40% increase of the current census, which now includes 492 objects. We estimate the completeness of our survey at between 66% and 78%, allowing for uncertainties in the distance estimates. We also perform a homogeneous model atmosphere analysis of this 40 pc sample and find a large fraction of massive white dwarfs, indicating that we are successfully recovering the more massive, and less luminous objects often missed in other surveys. We also show that the 40 pc sample is dominated by cool and old white dwarfs, which populate the faint end of the luminosity function, although trigonometric parallaxes will be needed to shape this part of the luminosity function more accurately. Finally, we identify 4 probable members of the 20 pc sample, 4 suspected double degenerate binaries, and we also report the discovery of two new ZZ Ceti pulsators.

We have identified outflows and bubbles in the Taurus molecular cloud based on the ∼100 deg² Five College Radio Astronomy Observatory ¹²CO(1-0) and ¹³CO(1-0) maps and the Spitzer young stellar object catalogs. In the main 44 deg² area of Taurus, we found 55 outflows, of which 31 were previously unknown. We also found 37 bubbles in the entire 100 deg² area of Taurus, none of which had been found previously. The total kinetic energy of the identified outflows is estimated to be $\sim 3.9\times {10}^{45}$ erg, which is 1% of the cloud turbulent energy. The total kinetic energy of the detected bubbles is estimated to be $\sim 9.2\times {10}^{46}$ erg, which is 29% of the turbulent energy of Taurus. The energy injection rate from the outflows is $\sim 1.3\times {10}^{33}\;\mathrm{erg}\;{{\rm{s}}}^{-1}$, which is 0.4–2 times the dissipation rate of the cloud turbulence. The energy injection rate from bubbles is $\sim 6.4\times {10}^{33}$ erg s⁻¹, which is 2–10 times the turbulent dissipation rate of the cloud. The gravitational binding energy of the cloud is $\sim 1.5\times {10}^{48}$ erg, that is, 385 and 16 times the energy of outflows and bubbles, respectively. We conclude that neither outflows nor bubbles can provide sufficient energy to balance the overall gravitational binding energy and the turbulent energy of Taurus. However, in the current epoch, stellar feedback is sufficient to maintain the observed turbulence in Taurus.

We have performed an unbiased, deep near-infrared survey toward the Aquila molecular cloud with a sky coverage of ∼1 deg². We identified 45 molecular hydrogen emission-line objects (MHOs), of which only 11 were previously known. Using the Spitzer archival data, we also identified 802 young stellar objects (YSOs) in this region. Based on the morphology and the location of MHOs and YSO candidates, we associate 43 MHOs with 40 YSO candidates. The distribution of jet length shows an exponential decrease in the number of outflows with increasing length, and the molecular hydrogen outflows seem to be oriented randomly. Moreover, there is no obvious correlation between jet lengths, jet opening angles, or jet ${{\rm{H}}}_{2}1-0S(1)$ luminosities and the spectral indices of the possible driving sources in this region. We also suggest that molecular hydrogen outflows in the Aquila molecular cloud are rather weak sources of turbulence, unlikely to generate the observed velocity dispersion in the region of survey.

We investigate the global cold dust properties of 85 nearby ($z\leqslant 0.5$) QSOs, chosen from the Palomar-Green sample of optically luminous quasars. We determine their infrared spectral energy distributions and estimate their rest-frame luminosities by combining Herschel data from 70 to 500 μm with near-infrared and mid-infrared measurements from the 2MASS and the Wide-Field Infrared Survey Explorer. In most sources the far-infrared (FIR) emission can be attributed to thermally heated dust. Single temperature modified blackbody fits to the FIR photometry give an average dust temperature for the sample of 33 K, with a standard deviation of 8 K, and an average dust mass of $7\times {10}^{6}\;{M}_{\odot }$ with a standard deviation of $9\times {10}^{6}\;{M}_{\odot }$. Estimates of star formation rates that are based on the FIR continuum emission correlate with those based on the 11.3 μm polycyclic aromatic hydrocarbon (PAH) feature, however, the star formation rates estimated from the FIR continuum are higher than those estimated from the 11.3 μm PAH emission. We attribute this result to a variety of factors including the possible destruction of the PAHs and that, in some sources, a fraction of the FIR originates from dust heated by the active galactic nucleus and by old stars.

Tomography of the solar corona can provide cruicial constraints for models of the low corona, unique information on changes in coronal structure and rotation rates, and a valuable boundary condition for models of the heliospheric solar wind. This is the first of a series of three papers which aim to create a set of maps of the coronal density over an extended period (1996-present). The papers will describe the data processing and calibration (this paper), the tomography method (Paper II), and the resulting atlas of coronal electron density at a height of 5 R_⊙ between years 1996–2014 (Paper III). This first paper presents a detailed description of data processing and calibration for the Large-Angle and Spectrometric Coronagraph (LASCO) C2 instrument on board the Solar and Heliospheric Observatory (SOHO) and the COR2 instruments of the Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) package on board the Solar Terrestial Relations Observatory (STEREO) A and B spacecraft. The methodology includes noise suppression, background subtraction, separation of large dynamic events, conversion of total brightness to K-coronal brightness, and simple functions for cross-calibration between C2/LASCO and COR2/SECCHI. Comparison of the brightness of stars between LASCO C2 total and polarized brightness (pB) observations provide in-flight calibration factors for the pB observations, resulting in considerable improved agreement between C2 and COR2 A, and elimination of curious artifacts in the C2 pB images. The cross-calibration between LASCO C2 and the STEREO coronagraphs allows, for the first time, the potential use of multi-spacecraft coronagraph data for tomography and for coronal mass ejection analysis.

We present an open-source update to the spherically symmetric, general-relativistic hydrodynamics, core-collapse supernova (CCSN) code GR1D. The source code is available at http://www.GR1Dcode.org. We extend its capabilities to include a general-relativistic treatment of neutrino transport based on the moment formalisms of Shibata et al. and Cardall et al. We pay special attention to implementing and testing numerical methods and approximations that lessen the computational demand of the transport scheme by removing the need to invert large matrices. This is especially important for the implementation and development of moment-like transport methods in two and three dimensions. A critical component of neutrino transport calculations is the neutrino–matter interaction coefficients that describe the production, absorption, scattering, and annihilation of neutrinos. In this article we also describe our open-source neutrino interaction library NuLib (available at http://www.nulib.org). We believe that an open-source approach to describing these interactions is one of the major steps needed to progress toward robust models of CCSNe and robust predictions of the neutrino signal. We show, via comparisons to full Boltzmann neutrino-transport simulations of CCSNe, that our neutrino transport code performs remarkably well. Furthermore, we show that the methods and approximations we employ to increase efficiency do not decrease the fidelity of our results. We also test the ability of our general-relativistic transport code to model failed CCSNe by evolving a 40-solar-mass progenitor to the onset of collapse to a black hole.

The overtone and multi-mode RR Lyrae stars in the globular cluster M3 are studied using a 200 day long, $B,V$, and ${I}_{{\rm{C}}}$ time-series photometry obtained in 2012. 70% of the 52 overtone variables observed show some kind of multi-periodicity (with additional frequency at ${f}_{0.61}={f}_{1{\rm{O}}}/0.61$ frequency ratio, Blazhko effect, double/multi-mode pulsation, and period doubling). A signal at the 0.587 frequency ratio to the fundamental-mode frequency is detected in the double-mode star, V13, which may be identified as the second radial overtone mode. If this mode identification is correct, than V13 is the first RR Lyrae star showing triple-mode pulsation of the first three radial modes. Either the Blazhko effect or the ${f}_{0.61}$ frequency (or both of these phenomena) appears in seven double-mode stars. The ${P}_{1{\rm{O}}}/{P}_{{\rm{F}}}$ period ratio of RRd stars showing the Blazhko effect are anomalous. A displacement of the main frequency component at the fundamental mode with the value of modulation frequency (or its half), is detected in three Blazhko RRd stars that are parallel with the appearance of the overtone-mode pulsation. The ${f}_{0.61}$ frequency appears in RRc stars that lie at the blue side of the double-mode region and in RRd stars, raising the suspicion that its occurrence may be connected to double-mode pulsation. The changes of the Blazhko and double-mode properties of the stars are also reviewed using the recent and archive photometric data.

Eruptions of classical novae are possible sources of lithium formation and gamma-ray emission. Nova remnants can also become Type Ia supernovae (SNe Ia). The contribution of novae to these phenomena depends on nova rates, which are not well established for the Galaxy. Here, we directly measure a Galactic bulge nova rate of 13.8 ± 2.6 ${\mathrm{yr}}^{-1}$. This measurement is much more accurate than any previous measurement of this kind thanks to many years' monitoring of the bulge by the Optical Gravitational Lensing Experiment (OGLE) survey. Our sample consists of 39 novae eruptions, ∼1/3 of which are OGLE-based discoveries. This long-term monitoring allows us to not only measure the nova rate but also to study in detail the light curves of 39 eruptions and more than 80 post-nova candidates. We measured orbital periods for 9 post-novae and 9 novae, and in 14 cases we procured the first estimates. The OGLE survey is very sensitive to the frequently erupting recurrent novae. We did not find any object similar to M31 2008-12a, which erupts once a year. The lack of detection indicates that there is only a small number of them in the Galactic bulge.

Two dedicated asteroid rotation-period surveys have been carried out in the R band with ∼20 minute cadence using the intermediate Palomar Transient Factory (iPTF) during 2014 January 6–9 and February 20–23. The total survey area covered 174 deg² in the ecliptic plane. Reliable rotation periods for 1438 asteroids are obtained from a larger data set of 6551 mostly main-belt asteroids, each with $\geqslant 10$ detections. Analysis of 1751, PTF-based, reliable rotation periods clearly shows the spin barrier at ∼2 hr for rubble-pile asteroids. We found a new large super-fast rotator, 2005 UW163, and another five candidates as well. For asteroids of $3\lt D\lt 15$ km, our spin-rate distribution shows a number decrease along with frequency after 5 rev day⁻¹, which is consistent with the results of the Asteroid Light Curve Database. The discrepancy between our work and that of Pravec et al. (update 2014 April 20) comes mainly from asteroids with ${\rm{\Delta }}m\lt 0.2$ mag, which could be the result of different survey strategies. For asteroids with $D\lt 3$ km, we see a significant number drop at f = 6 rev day⁻¹. The relatively short YORP effect timescale for small asteroids could have spun up those elongated objects to reach their spin-rate limit resulting in breakup to create such a number deficiency. We also see that the C-type asteroids show a smaller spin-rate limit than the S-type, which agrees with the general impression that C-type asteroids have a lower bulk density than S-type asteroids.

The ¹⁸O/¹⁷O isotopic ratio of oxygen is a crucial measure of the secular enrichment of the interstellar medium by ejecta from high-mass versus intermediate-mass stars. So far, however, there is a lack of data, particularly from the Galactic center (GC) region. Therefore, we have mapped typical molecular clouds in this region in the J = 1–0 lines of C¹⁸O and C¹⁷O with the Delingha 13.7 m telescope (DLH). Complementary pointed observations toward selected positions throughout the GC region were obtained with the IRAM 30 m and Mopra 22 m telescopes. C¹⁸O/C¹⁷O abundance ratios reflecting the ¹⁸O/¹⁷O isotope ratios were obtained from integrated intensity ratios of C¹⁸O and C¹⁷O. For the first time, C¹⁸O/C¹⁷O abundance ratios are determined for Sgr C (V ∼ −58 km s⁻¹), Sgr D (V ∼ 80 km s⁻¹), and the 13 complex (V ∼ 80 km s⁻¹). Through our mapping observations, abundance ratios are also obtained for Sgr A (∼0 and ∼50 km s⁻¹ component) and Sgr B2 (∼60 km s⁻¹), which are consistent with the results from previous single-point observations. Our frequency-corrected abundance ratios of the GC clouds range from 2.58 ± 0.07 (Sgr D, V ∼ 80 km s⁻¹, DLH) to 3.54 ± 0.12 (Sgr A, ∼50 km s⁻¹). In addition, strong narrow components (line width less than 5 km s⁻¹) from the foreground clouds are detected toward Sgr D (−18 km s⁻¹), the 13 complex (−18 km s⁻¹), and M+5.3−0.3 (22 km s⁻¹), with a larger abundance ratio around 4.0. Our results show a clear trend of lower C¹⁸O/C¹⁷O abundance ratios toward the GC region relative to molecular clouds in the Galactic disk. Furthermore, even inside the GC region, ratios appear not to be uniform. The low GC values are consistent with an inside-out formation scenario for our Galaxy.

We present the spectroscopic redshift catalog from a wide-field survey of the fields of 28 galaxy-mass strong gravitational lenses. We discuss the acquisition and reduction of the survey data, collected over 40 nights of 6.5 m MMT and Magellan time, employing four different multiobject spectrographs. We determine that no biases are introduced by combining data sets obtained with different telescope and spectrograph combinations. Special care is taken to determine redshift uncertainties using repeat observations. The redshift catalog consists of 9,768 new and unique galaxy redshifts. 82.4% of the catalog redshifts are between z = 0.1 and z = 0.7, and the catalog median redshift is ${z}_{\mathrm{med}}=0.36$. The data from this survey will be used to study the lens environments and line-of-sight structures to gain a better understanding of the effects of large-scale structure on lens statistics and lens-derived parameters.

In this work, for the first time, we present a numerical study of Bondi–Hoyle accretion with density gradients in the fully relativistic regime. In this context, we consider the accretion onto a Kerr black hole (BH) of a supersonic ideal gas with density gradients perpendicular to the relative motion. The parameters of interest in this study are the Mach number, ${\mathcal{M}}$, the spin of the BH, a, and the density-gradient parameter of the gas, _ρ. We show that, unlike in the Newtonian case, all of the studied cases, especially those with a density gradient, approach a stationary flow pattern. To illustrate that the system reaches a steady state, we calculate the mass and angular momentum accretion rates on a spherical surface almost located at the event horizon. In the particular case of ${\mathcal{M}}=1$, _ρ = 0.5, and BH spin a = 0.5, we observe a disk-like configuration surrounding the BH. Finally, we present the gas morphology and some of its properties.

Astrophysical research in recent decades has made significant progress thanks to the availability of various N-body simulation techniques. With the rapid development of high-performance computing technologies, modern simulations have been able to use the computing power of massively parallel clusters with more than 10⁵ GPU cores. While unprecedented accuracy and dynamical scales have been achieved, the enormous amount of data being generated continuously poses great challenges for the subsequent procedures of data analysis and archiving. In this paper, we propose an adaptive storage scheme for simulation data, inspired by the block time step (BTS) integration scheme found in a number of direct N-body integrators available nowadays, as an urgent response to these challenges. The proposed scheme, namely, the BTS storage scheme, works by minimizing the data redundancy by assigning individual output frequencies to the data as required by the researcher. As demonstrated by benchmarks, the proposed scheme is applicable to a wide variety of simulations. Despite the main focus of developing a solution for direct N-body simulation data, the methodology is transferable for grid-based or tree-based simulations where hierarchical time stepping is used.

We have extracted the WISE (Wide-field Infrared Survey Explorer) single-exposure data for a sample of 72 polars, which are highly magnetic cataclysmic variables (CVs). We combine these data with both published and unpublished optical and infrared data to explore the origins of the large amplitude variations seen in these systems. In nearly every case, we find evidence for cyclotron emission in the WISE bandpasses. We find that the derived magnetic field strengths for some polars are either too high, or cyclotron emission from lower field components, located spatially coincident to the main accreting poles, must be occurring. We have also estimated field strengths for a number of polars where no such values exist. In addition, contrary to expectations, we find that emission from the fundamental cyclotron harmonic (n = 1) appears to be nearly always present when the magnetic field is of the appropriate strength that it falls within a WISE bandpass. We find that the light curves for RBS 490, an ultrashort-period (46 minutes) CV, suggest that it is a polar. Modeling its spectrum indicates that its donor star is much hotter than expected. Nearly all of the detected polars show 11.5 μm ("W3 band") excesses. The general lack of variability seen in the W3 bandpass light curves for higher-field polars demonstrates that these excesses are probably not due to cyclotron emission. There is circumstantial evidence that these excesses can be attributed to bremsstrahlung emission from their accretion streams. Reduction of the Spitzer 24 μm image of V1500 Cyg shows that it appears to be located at the center of a small nebula.

We present the results of a near-infrared (NIR) spectroscopic follow-up survey of 182 M4–L7 low-mass stars and brown dwarfs (BDs) from the BANYAN All-Sky Survey (BASS) for candidate members of nearby, young moving groups (YMGs). We confirm signs of low gravity for 42 new BD discoveries with estimated masses between 8 and 75 ${M}_{\mathrm{Jup}}$ and identify previously unrecognized signs of low gravity for 24 known BDs. We refine the fraction of low-gravity dwarfs in the high-probability BASS sample to ∼82%. We use this unique sample of 66 young BDs, supplemented with 22 young BDs from the literature, to construct new empirical NIR absolute magnitude and color sequences for low-gravity BDs. We show that low-resolution NIR spectroscopy alone cannot differentiate between the ages of YMGs younger than ∼120 Myr, and that the BT-Settl atmosphere models do not reproduce well the dust clouds in field or low-gravity L-type dwarfs. We obtain a spectroscopic confirmation of low gravity for 2MASS J14252798–3650229, which is a new ∼27 ${M}_{\mathrm{Jup}}$, L4 γ bona fide member of AB Doradus. We identify a total of 19 new low-gravity candidate members of YMGs with estimated masses below 13 ${M}_{\mathrm{Jup}}$, 7 of which have kinematically estimated distances within 40 pc. These objects will be valuable benchmarks for a detailed atmospheric characterization of planetary-mass objects with the next generation of instruments. We find 16 strong candidate members of the Tucana–Horologium association with estimated masses between 12.5 and 14 ${M}_{\mathrm{Jup}}$, a regime where our study was particularly sensitive. This would indicate that for this association there is at least one isolated object in this mass range for every ${17.5}_{-5.0}^{+6.6}$ main-sequence stellar member, a number significantly higher than expected based on standard log-normal initial mass function, however, in the absence of radial velocity and parallax measurements for all of them, it is likely that this over-density is caused by a number of young interlopers from other associations.

Modeling large-scale sky survey observations is a key driver for the continuing development of high-resolution, large-volume, cosmological simulations. We report the first results from the "Q Continuum" cosmological N-body simulation run carried out on the GPU-accelerated supercomputer Titan. The simulation encompasses a volume of ${(1300\;\mathrm{Mpc})}^{3}$ and evolves more than half a trillion particles, leading to a particle mass resolution of ${m}_{{\rm{p}}}\simeq 1.5\cdot {10}^{8}\;$${M}_{\odot }$. At this mass resolution, the Q Continuum run is currently the largest cosmology simulation available. It enables the construction of detailed synthetic sky catalogs, encompassing different modeling methodologies, including semi-analytic modeling and sub-halo abundance matching in a large, cosmological volume. Here we describe the simulation and outputs in detail and present first results for a range of cosmological statistics, such as mass power spectra, halo mass functions, and halo mass-concentration relations for different epochs. We also provide details on challenges connected to running a simulation on almost 90% of Titan, one of the fastest supercomputers in the world, including our usage of Titan's GPU accelerators.

Transition Edge Sensor microcalorimeters can measure X-ray and gamma-ray energies with very high energy resolution and high photon-collection efficiency. For this technology to reach its full potential in future X-ray observatories, each sensor must be able to measure hundreds or even thousands of photon energies per second. Current "optimal filtering" approaches to achieve the best possible energy resolution work only for photons that are well isolated in time, a requirement which is in direct conflict with the need for high-rate measurements. We describe a new analysis procedure to allow fitting for the pulse height of all photons even in the presence of heavy pulse pile-up. In the limit of isolated pulses, the technique reduces to standard optimal filtering with long records. We employ reasonable approximations to the noise covariance function in order to render this procedure computationally viable even for very long data records. The technique is employed to analyze X-ray emission spectra at 600 eV and 6 keV at rates up to 250 counts s⁻¹ in microcalorimeters having exponential signal decay times of approximately 1.2 ms.

Using the high spatiotemporal resolution extreme ultraviolet (EUV) observations of the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory, we conduct a statistical study of the observational properties of the coronal EUV propagating fronts. We find that it might be a universal phenomenon for two types of fronts to coexist in a large solar eruptive event. It is consistent with the hybrid model of EUV propagating fronts, which predicts that coronal EUV propagating fronts consist of both a fast magneto-acoustic wave and a nonwave component. We find that the morphologies, propagation behaviors, and kinematic features of the two EUV propagating fronts are completely different from each other. The fast magneto-acoustic wave fronts are almost isotropic. They travel continuously from the flaring region across multiple magnetic polarities to global distances. On the other hand, the slow nonwave fronts appear as anisotropic and sequential patches of EUV brightening. Each patch propagates locally in the magnetic domains where the magnetic field lines connect to the bottom boundary and stops at the magnetic domain boundaries. Within each magnetic domain, the velocities of the slow patchy nonwave component are an order of magnitude lower than that of the fast-wave component. However, the patches of the slow EUV propagating front can jump from one magnetic domain to a remote one. The velocities of such a transit between different magnetic domains are about one-third to one-half of those of the fast-wave component. The results show that the velocities of the nonwave component, both within one magnetic domain and between different magnetic domains, are highly nonuniform due to the inhomogeneity of the magnetic field in the lower atmosphere.

In this thorough study, we focus on the indirect detection of dark matter (DM) through the examination of unexplained galactic and extragalactic γ-ray signatures for a low-mass DM model. For this purpose, we consider a simple Higgs-portal DM model, namely, the inert Higgs doublet model (IHDM) where the SM is extended with an additional complex SU(2)_L doublet scalar. The stability of the DM candidate in this model, i.e., the lightest neutral scalar component of the extra doublet, is ensured by imposing discrete ${{\mathbb{Z}}}_{2}$ symmetry. The reduced-${\chi }^{2}$ analysis using theoretical, experimental, and observational constraints suggests that the best-fit value of DM mass in this model is ∼63.5 GeV. We analyze the anomalous GeV γ-ray excess from the Galactic Center in light of the best-fit IHDM parameters. We further check the consistency of the best-fit IHDM parameters with the Fermi Large Area Telescope (Fermi-LAT) obtained limits on photon flux for 18 Milky Way dwarf spheroidal satellite galaxies (dSphs) known to be mostly dominated by DM. Also, since the γ-ray signal from DM annihilation is assumed to be embedded within the extragalactic γ-ray background (EGB), the theoretical calculations of photon flux for the best-fit parameter point in the IHDM framework are compared with the Fermi-LAT results for diffuse and isotropic EGB for different extragalactic and astrophysical background parametrizations. We show that the low-mass DM in the IHDM framework can satisfactorily account for all of the observed continuum γ-ray fluxes originating from galactic and extragalactic sources. The extensive analysis performed in this work is valid for any Higgs-portal model with DM mass comparable to that considered in this work.

We develop a time-dependent, multi-group, multi-dimensional relativistic radiative transfer code, which is required to numerically investigate radiation from relativistic fluids that are involved in, e.g., gamma-ray bursts and active galactic nuclei. The code is based on the spherical harmonic discrete ordinate method (SHDOM) which evaluates a source function including anisotropic scattering in spherical harmonics and implicitly solves the static radiative transfer equation with ray tracing in discrete ordinates. We implement treatments of time dependence, multi-frequency bins, Lorentz transformation, and elastic Thomson and inelastic Compton scattering to the publicly available SHDOM code. Our code adopts a mixed-frame approach; the source function is evaluated in the comoving frame, whereas the radiative transfer equation is solved in the laboratory frame. This implementation is validated using various test problems and comparisons with the results from a relativistic Monte Carlo code. These validations confirm that the code correctly calculates the intensity and its evolution in the computational domain. The code enables us to obtain an Eddington tensor that relates the first and third moments of intensity (energy density and radiation pressure) and is frequently used as a closure relation in radiation hydrodynamics calculations.

We identify 885,503 type 1 quasar candidates to $i\lesssim 22$ using the combination of optical and mid-IR photometry. Optical photometry is taken from the Sloan Digital Sky Survey-III: Baryon Oscillation Spectroscopic Survey (SDSS-III/BOSS), while mid-IR photometry comes from a combination of data from the Wide-field Infrared Survey Explorer (WISE) "AllWISE" data release and several large-area Spitzer Space Telescope fields. Selection is based on a Bayesian kernel density algorithm with a training sample of 157,701 spectroscopically confirmed type 1 quasars with both optical and mid-IR data. Of the quasar candidates, 733,713 lack spectroscopic confirmation (and 305,623 are objects that we have not previously classified as photometric quasar candidates). These candidates include 7874 objects targeted as high-probability potential quasars with $3.5\lt z\lt 5$ (of which 6779 are new photometric candidates). Our algorithm is more complete to $z\gt 3.5$ than the traditional mid-IR selection "wedges" and to $2.2\lt z\lt 3.5$ quasars than the SDSS-III/BOSS project. Number counts and luminosity function analysis suggest that the resulting catalog is relatively complete to known quasars and is identifying new high-z quasars at $z\gt 3$. This catalog paves the way for luminosity-dependent clustering investigations of large numbers of faint, high-redshift quasars and for further machine-learning quasar selection using Spitzer and WISE data combined with other large-area optical imaging surveys.

We present a new set of models for intermediate-mass asymptotic giant branch (AGB) stars (4.0, 5.0, and 6.0 M_⊙) at different metallicities (−2.15 ≤ [Fe/H] ≤ +0.15). This set integrates the existing models for low-mass AGB stars (1.3 ≤ M/M_⊙ ≤ 3.0) already included in the FRUITY database. We describe the physical and chemical evolution of the computed models from the main sequence up to the end of the AGB phase. Due to less efficient third dredge up episodes, models with large core masses show modest surface enhancements. This effect is due to the fact that the interpulse phases are short and, therefore, thermal pulses (TPs) are weak. Moreover, the high temperature at the base of the convective envelope prevents it from deeply penetrating the underlying radiative layers. Depending on the initial stellar mass, the heavy element nucleosynthesis is dominated by different neutron sources. In particular, the s-process distributions of the more massive models are dominated by the ²²Ne(α,n)²⁵Mg reaction, which is efficiently activated during TPs. At low metallicities, our models undergo hot bottom burning and hot third dredge up. We compare our theoretical final core masses to available white dwarf observations. Moreover, we quantify the influence intermediate-mass models have on the carbon star luminosity function. Finally, we present the upgrade of the FRUITY web interface, which now also includes the physical quantities of the TP-AGB phase for all of the models included in the database (ph-FRUITY).

We present results from Chandra ACIS-I and Karl G. Jansky Very Large Array 6 cm continuum observations of the IRAS 20126+4104 massive star-forming region. We detect 150 X-ray sources within the 17' × 17' ACIS-I field, and a total of 13 radio sources within the 92 primary beam at 4.9 GHz. Among these observtions are the first 6 cm detections of the central sources reported by Hofner et al., namely, I20N1, I20S, and I20var. A new variable radio source is also reported. Searching the 2MASS archive, we identified 88 near-infrared (NIR) counterparts to the X-ray sources. Only four of the X-ray sources had 6 cm counterparts. Based on an NIR color–color analysis and on the Besançon simulation of Galactic stellar populations, we estimate that approximately 80 X-ray sources are associated with this massive star-forming region. We detect an increasing surface density of X-ray sources toward the massive protostar and infer the presence of a cluster of at least 43 young stellar objects within a distance of 1.2 pc from the massive protostar.

We present Spitzer IRAC 3.6–8 $\mu {\rm{m}}$ and Multiband Imaging Photometer $24\;\mu {\rm{m}}$ point-source catalogs for seven galaxies: NGC 6822, M33, NGC 300, NGC 2403, M81, NGC 0247, and NGC 7793. The catalogs contain a total of ∼300,000 sources and were created by dual-band selection of sources with $\gt 3\sigma$ detections at both 3.6 and $4.5\;\mu {\rm{m}}$. The source lists become significantly incomplete near ${m}_{3.6}={m}_{4.5}\simeq 18$. We complement the 3.6 and $4.5\;\mu {\rm{m}}$ fluxes with 5.8, 8.0, and $24\;\mu {\rm{m}}$ fluxes or $3\sigma$ upper limits using a combination of PSF and aperture photometry. This catalog is a resource as an archive for studying mid-infrared transients and for planning observations with the James Webb Space Telescope.