adsabs/WIESP2022-NER huggingface dataset:
Paper: 2021MNRAS.505..628S (fulltext)
we take the average over contributions from all pairs of cells (and the third associated cell that is uniquely determined by the triangular condition) that fall into that bin. We do not look at the bispectrum bins unless at least some combination of the wave numbers in that bin satisfies a triangular condition. To avoid counting equivalent triplets multiple times, we impose a condition k 1 > k 2 > k 3 . Fig. A1 shows the average nonlinear and linear power spectra of matter particles from Quijote simulations. We rescaled the linear power spectrum to have a matching amplitude at small wave numbers. The two are reasonably close for large-scale modes (up to k ∼ 0.1 h Mpc −1 after which the additional power in the nonlinear power spectrum becomes visible. The partial erasure of the BAO signal is also visible by eye. Fig. A2 shows the average bispectrum of matter particles from Quijote simulations at z = 0 as a function of the longest wave number. Features in the shape of this three-dimensional function provide additional opportunities for the standard ruler test. Figure A1. Non-linear power spectrum at z = 0 (blue) and a linear power spectrum (black) of Quijote matter particles. The linear power spectrum is measured from particles at z = 99 and rescaled to have a matching amplitude on large scales. Figure A2. Bispectrum of Quijote matter particles at z = 0 as a function of the largest wave number k 1 . Multiple points at the same abscissa show all bispectrum bins that share that value of k 1 but have different values of k 2 and k 3 . We multiply the bispectrum by a factor of k 1 k 2 k 3 . This factor is proportional to the number of fundamental triangles in the bin and separates different points for better visibility. To estimate the covariance of these measurements, , by computing the sample covariance over 8,000 Quijote simulations, X i l are the power spectrum and bispectrum measurements, where the first index goes over the bins and the second index goes over simulations. N sim is the number of simulations. Fig. A3 shows the correlation matrix of these measurements defined as We ordered the measurements so that the first 50 elements are binned P ( k ) up to k max = 0.5 h Mpc −1 . They are followed by binned B ( k 1 , k 2 , k 3 ) arranged in such a way that the bispectrum bin with smaller k 1 goes first (smaller k 2 when k 1 are equal, and smaller k 3 when both k 1 and k 2 are equal). The first 150 bins arranged in this way accommodate all bispectra up to k 1, max = 0.1 h Mpc −1 . The correlation between power spectra at high wave numbers is clearly visible in this plot. The bispectrum measurements are also correlated between themselves and the power spectra but to a lesser extent. Figure A3. Correlation coefficient of the power spectrum (first 50 bins, goes up to k max = 0.5 h Mpc −1 ) and the bispectrum (last 150 bins, goes up to k 1, max = 0.1 h Mpc −1 ) measurements. Colourmap is adjusted in such a way that red, blue, and white cells
Paper: 2016MNRAS.460.1801P (acknowledgments)
We thank Andrei Mesinger for useful comments on the manuscript. AP gratefully acknowledges the use of facilities at ETH, Zürich during the early phases of this work. The research of HP is supported by the Shyama Prasad Mukherjee Fellowship of CSIR, India.
Paper: 2018MNRAS.473.1719L (fulltext)
→ ∞. This arises from the fact that the gravitational restoring force contains an imaginary component, which acts as an anti-damping (growth) term and dominates the Chandrasekhar dynamical friction when the angular velocity is sufficiently large. Order-of-magnitude estimates for the various time-scales (damping and oscillation) were computed, and their ramifications in the context of this rotating system were explored. We also demonstrated a formal equivalence between Eddington black hole accretion and dynamical friction, thereby ensuring that both these problems can be treated in a unified manner. Through a comparison of the time-scales, it was shown that the Eddington accretion time-scale is faster in some instances, thereby constituting the more dominant effect. However, as black holes cannot accrete matter in such a fashion indefinitely, the limitations of this paradigm were also duly indicated. We have discussed some of the limitations of our formalism in Sections 1 and 5 , since some of the inherent assumptions are not accurate over the entire domain of the galaxy. However, it may be possible to use some of the results obtained herein to study the dynamics near the Galactic Centre (Genzel et al. 2010 ). For instance, recent numerical simulations of supermassive black hole binaries, with Galactic rotation taken into account, suggest that they can be significantly displaced from the Galactic Centre (Awais Mirza et al. 2017 ). Hence, the formalism developed in this paper may provide a heuristic explanation for such phenomena (although we have considered only single black holes in our analysis). Additionally, as the solutions obtained are analytical in nature, the main purpose of the paper is to arguably provide a benchmark solution against which numerical simulations can be compared. Lastly, we note that our treatment is quite general as it is Newtonian in nature, and does not invoke any of the specific features of black holes – it is equally applicable to a massive object in a sea of light particles. For instance, it may be possible to consider Saturn as our massive object, and the (moonlets that constitute) rings of Saturn as the lighter particles, analogous to the works of Griv et al. ( 2000 ) and Griv, Gedalin Yuan ( 2003 ). Moreover, it might be possible to also model axisymmetric systems via this formalism, in the regimes specified herein, such as discs with a Miyamoto–Nagai gravitational potential (Miyamoto Nagai 1975 ). By employing the same mathematical methods employed herein, we can also model the dynamics of a Reissner–Nordström (charged) black hole interacting with a constant galactic magnetic field via the Lorentz force. APPENDIX A: DYNAMICAL FRICTION IN A ROTATING ISOTROPIC CLUSTER Consider a cluster described by a potential–density pair together with an ergodic distribution function (DF) . If we introduce an overall rotation to the cluster, then it was argued in Lynden-Bell ( 1967 ) that the new DF can be obtained by the
Paper: 2020MNRAS.491.3217K (fulltext)
If the synchrotron losses dominate as a radiative cooling channel, the product of the maximum attainable energy and the square root of the magnetic field strength, , can be taken as a measure of the accelerator efficiency. The extension of the electron spectrum to PeV energies in the magnetic field exceeding , tells us that in the Crab Nebula we deal with an acceleration efficiency approaching the ideal MHD limit (i.e. the strength of the accelerating electric field gets close to the strength of the magnetic field). Another important issue of the spectral modelling of the Crab Nebula is related to the so-called Crab flares – intense flashes of synchrotron radiation extending to GeV energies (Abdo et al. 2011 ; Tavani et al. 2011 ). The short variability time-scale and the distinct spectral shape of the flaring component require a magnetic field that is significantly larger than the average nebular field, , a non-ideal MHD configuration, and/or relativistic motions with a large bulk Lorentz factor (see Bühler Blandford 2014 , and references therein). Even under these extreme conditions, the Crab flares require the presence of electrons with energy exceeding a few PeV. The Crab flares are likely to be formed in a region(s) quite different from the site(s) where the steady component of radiation is produced. In both cases, the acceleration of electrons proceeds with efficiency close to or even beyond the ideal MHD limit. The tough efficiency requirement for the acceleration of the wind electrons can be significantly relaxed assuming that another component of electrons is responsible for the multi-MeV gamma-rays. This hypothesis is supported by a non-smooth transition between the spectra of the INTErnational Gamma-Ray Astrophysics Laboratory ( INTEGRAL ) and the Imaging Compton Telescope ( COMPTEL ). If this spectral feature is real, then it is better to reproduce the spectral structure at multi-MeV energies by invoking an additional component of electrons with a hard energy distribution (Aharonian Atoyan 1998 ). The currently available data do not exclude a significantly stronger magnetic field in the regions where this hypothetical hard distribution is localized (Aharonian Atoyan 1998 ). Therefore, the IC emission produced by electrons from the hard component could be suppressed compared with the IC radiation associated with the standard wind electron component. The synchrotron radiation alone does not allow us to infer information about the electrons and magnetic fields in this most critical – for highest energy electrons – MeV/GeV energy region. For any reasonable magnetic field, the MeV synchrotron radiation is produced by electrons of many hundreds of TeV. Therefore, the UHE gamma-rays produced by the same electrons through the IC scattering contain information that can shed light on both the electron energy distribution and the magnetic field strength. In this regard, the recently reported detection of gamma-ray fluxes above 100 TeV
Paper: 2015A&A...573A.136I (acknowledgments)
We are grateful to the anonymous referee for valuable comments, which improved the analysis and the presentation of the results. We gratefully acknowledge Knut Olsen for providing the ATCA/Parkes H i data in a preferred format and for useful suggestions. We are grateful to Smitha Subramanian and C. S. Stalin for the remarks and suggestions, which improved the presentation of the paper. We thank Gurtina Besla for her comments on the paper. Thanks to Arun Surya and Rathnakumar for the valuable support in matlab programming.
Paper: 2018ApJ...863..120W (fulltext)
(cf. Equation ( 1 )). Note that the ionization fractions derived in Ghavamian et al. ( 2002 ) are insensitive to the total preshock gas density n 0 . 2.2.2. Magellanic Supernova Remnants Ghavamian et al. ( 2003 ) study the entire remnant of DEM L71 using Fabry–Perot imaging spectroscopy, with preshock densities inferred from Chandra ACIS-S spectra modeled by Rakowski et al. ( 2003 ). The latter find a range of preshock densities along different regions of the rim of the remnant, roughly bounded by the range ≈0.5–1.5 cm −3 . In particular, n 0 ≈ 0.5 cm −3 is consistent with the majority of the eastern rim of the remnant, while in portions of the northwest rim, n 0 ≈ 1.5 cm −3 . Modeling the observed collisionally excited hydrogen-Balmer emission, Ghavamian et al. ( 2003 ) conclude that a wide range in neutral fraction may be plausible, but that would be necessary in order to produce detectable H α emission. Ghavamian et al. ( 2007 ) revisited DEM L71 in the far-UV, as well as the LMC remnants 0509-67.5, 0519-69.0, and 0548-70.4, using spectra obtained from the Far Ultraviolet Spectroscopic Explorer . The ratio of fluxes in Ly β and O VI 1032 Å depends linearly on the preshock neutral fraction; the observed ratio in DEM L71 requires a hydrogen neutral fraction of 20–40%, consistent with previous limits. No UV lines were found for the remnant 0548-70.4. For the remnants 0509-67.5 and 0519-69.0, the same method constrains the neutral hydrogen fraction in the surrounding ISM to >40%. The best-fitting ambient densities can be found by comparing the present size and ionization state of the remnant with hydrodynamical models: recently, Kosenko et al. ( 2014 ) found n 0 = 0.1–0.3 cm −3 for 0509-67.5, and n 0 = 1.0–2.0 cm −3 for 0519-69.0, although Kosenko et al. ( 2010 ) report densities as high as 2.4 cm −3 . As a conservative estimate, we adopt 0.3 cm −3 and 2.4 cm −3 as our fiducial ISM densities for 0509-67.5 and 0519-69.0, respectively. The radius of the forward shock for both remnants is ∼4 pc, for an LMC distance of 50 kpc. 3. Constraints on the Nature of the Progenitors of Nearby SNe Ia 3.1. Flash Ionization We may now investigate the extent to which the presence of neutral hydrogen at the present radii of all remnants considered above constrains the release of ionizing photons in the last τ rec ≈ 100,000 years. Chevalier Raymond ( 1978 ) were the first to consider the simplest case, a “burst” of ionizing photons from the supernova itself. For a present shock radius R and mean ambient density n , the total number of hydrogen-ionizing photons emitted in such a burst must have been fewer than 4 π R 3 n /3 ≈ (0.2–6) × 10 58 for SN 1006, 0509-67.5, 0519-69.0, and DEM L71 (see Table 1 ). Notably, this upper bound applies not only to the shock breakout from the supernova itself, but to any short-lived phase that the progenitor or its companion underwent immediately preceding or following the explosion, such as any briefly hot, luminous surviving WD
Paper: 2016MNRAS.459..871K (acknowledgments)
We thank Calcul Québec for computational resources. This research was partially supported by the Natural Sciences and Engineering Research Council of Canada and the Faculté des Études Supérieures et de la Recherche de l'Université de Moncton. This paper is based on: (1) observations obtained at the CFHT which is operated by the National Research Council of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii; and (2) data obtained from the ESO Science Archive Facility under request number 72877.
Paper: 2016ApJ...827...67M (fulltext)
blazar-like counterparts of the UGSs. 3. We describe the statistically significant correlations between the γ -ray photon index and the mid-IR colors for both the whole sample of Fermi blazars and the BZB and BZQ spectral classes separately, the basis of the IR– γ -ray connection. This correlation appears “stronger” than the well-known radio– γ -ray connection because it involves the spectral shapes of the Fermi blazars over ∼10 orders of magnitude and not only their fluxes. 4. We argue that the peculiar mid-IR colors of Fermi blazars do not depend on their γ -ray photon index. In turn, the IR– γ -ray connection is unexpected. We have also highlighted its potential use to implement the search for blazar-like counterparts of the Fermi UGSs. 5. We show that a large fraction of the BCUs listed in the 3FGL whose WISE counterpart has mid-IR colors consistent with the WISE Gamma-ray Strip have Fermi spectral index values consistent with the IR– γ -ray connection. Taking advantage of the overwhelming fraction of Fermi blazars detected in the WISE all-sky survey (i.e., ∼99%) in the first two mid-IR filters, we suggest that a comprehensive investigation of their IR properties at the light of the IR– γ -ray connection described in this paper can represent a powerful tool to reveal the real fraction of Fermi blazars hidden within the sample of UGSs. We thank the anonymous referee for useful comments that led to improvements in the paper. We also thank J. Ballet for helpful discussions. F.M. gratefully acknowledges the financial support of the Programma Giovani Ricercatori—Rita Levi Montalcini—Rientro dei Cervelli (2012) awarded by the Italian Ministry of Education, Universities and Research (MIUR). This research has made use of data obtained from the high-energy Astrophysics Science Archive Research Center (HEASARC) provided by NASA’s Goddard Space Flight Center. The NASA/IPAC Extragalactic Database (NED) is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. Part of this work is based on the NVSS (NRAO VLA Sky Survey). The National Radio Astronomy Observatory is operated by Associated Universities, Inc., under contract with the National Science Foundation and on the VLA Low-frequency Sky Survey (VLSS). The Molonglo Observatory site manager, Duncan Campbell-Wilson, and the staff, Jeff Webb, Michael White, and John Barry, are responsible for the smooth operation of the Molonglo Observatory Synthesis Telescope (MOST) and the day-to-day observing program of SUMSS. SUMSS is dedicated to Michael Large, whose expertise and vision made the project possible. The MOST is operated by the School of Physics with the support of the Australian Research Council and the Science Foundation for Physics within the University of Sydney. This publication makes use of data products from the Wide-field Infrared Survey Explorer , which is a joint project of the University
Paper: 2020ApJ...888...81L (fulltext)
5 5 TYC 1323-1592-1 (=LS 36; Stephenson Sanduleak 1971 ) is an O8 Vz star newly identified here. It has the narrowest line profiles among the LAMOST medium-resolution spectra of O dwarfs, hence, we assume ≃ 0; the exact value is of little consequence, as long as it is small (which is clearly the case). to estimate P ( λ ), which is the rectified intrinsic line profile without rotation. 2. For an assumed , we fitted the functionto S ( λ ), which is the observed He i λ 5016 profile for each ON star. Here, ⨂ is the convolution operator; is the rotational broadening function (Gray 2005 ); and are fit parameters. 3. A figure of merit, , was calculated for trial values from 180 to 400 at steps of 7 . A refined best-fit was finally obtained by fitting a third-order polynomial to the 11 ξ values about the smallest one for each star. To estimate (internal) uncertainties on the velocities, we assumed the best-fit model to be representative of the true profile, added Gaussian noise matching the observed spectra, and measured v R and v e sin i as above, repeating the process 10 4 times. Our final results for and are: (LS I +61 28) and (HDE 236672). The He i λ 5016 rectified observations and adopted models are shown in Figure 2 . If macroturbulence were more important in the target stars than in TYC 1323-1592-1, our values may be upper limits (Howarth et al. 1997 ; Simón-Díaz Herrero 2007 ), although rotational broadening clearly dominates for the rapid rotators. Figure 2. He i λ 5016 profiles of LS I +61 28 and HDE 236672. The red lines are the best-fit rotationally broadened models. We also measured the radial velocity of He i λ 5016, along with other lines of hydrogen and helium, in the low-resolution spectra at our disposal, and find no evidence for radial-velocity variability in excess of ∼20 (i.e., ∼0.1 of the resolution element). 3. Kinematics of Galactic ON Stars Gaia DR2 provides parallaxes and proper motions with unprecedented precision for more than a billion stars (Gaia Collaboration et al. 2018 ). By combining this information with radial velocities, we can determine the kinematics of ON stars in the Galaxy. In addition to the two new ONn stars reported here, we investigate all those ON stars satisfying the following criteria: (i) not classified as a supergiant, (ii) parallax accuracy of , and (iii) a radial velocity reported in Table 2 of Walborn et al. ( 2011 ). This sample is summarized in Table 2 . Other than for their rotation velocities, the dozen sample stars have similar spectral characteristics and similar effective temperatures (and thus may have arisen through similar processes). Table 2 Kinematic Parameters for the ON-star Sample Note. Spectral types (column 3) and binary indicators (column 10) adopted from Walborn et al. ( 2011 ), except HDE 236672 and LS I +61 28 (this paper). Projected rotational velocities are from Martins et al. ( 2015b ), Howarth et al. ( 1997 ), and this paper. In column 9, . We used Markov Chain Monte
Paper: 2020ApJ...905...80G (fulltext)
to calculate the percentage retention of Si and C by the mantle. Upon simulating the sputtering yield for two cases, one with a 0.02 μ m thick ice mantle and another without an ice mantle, we observe a higher number of recoils in the grain with an ice mantle. This shows that having an ice mantle accelerates the sputtering process and increases the collision cascade inside the grain. Due to the limitations of using Monte Carlo simulations, it is hard to arrive at the exact change in collision cascade due to the ice mantle. Nonetheless, the central point of this result is to emphasize the destructive nature of the ice mantle along with its protective nature when it retains the ejected atoms from the core. This increase might not affect the absolute value of sputtering; however, it makes the grain more amorphous. Also, for relatively slow-moving projectiles such as shock-wave-accelerated particles, there would be even higher amorphization. Most of the presolar SiC grains analyzed in the laboratory have been reported to be crystalline and even spectroscopically detected as a 11 μ m feature. The absence of amorphous SiC in both the laboratory and spectroscopically has been under discussion for the past two decades, mainly because the majority of presolar silicate grains studied in the laboratory have amorphous structure (Vollmer et al. 2009 ). Both amorphous and crystalline (10%) silicates have been observed around AGB stars and young main-sequence stars (Demyk et al. 2000 ). To understand the grain shape and size dependence on infrared spectra, Speck et al. ( 2005 ) compared IR spectra from various polytypes of SiC in the laboratory. This study indicated the possibility of a 9 μ m feature being related to amorphous SiC. As for the laboratory measurements, this difference between presolar silicates and SiC mainly arises due to the different identification/separation methods. Presolar silicates have been identified based on in situ measurement, whereas SiCs are chemically separated. The in situ measurements within the meteorite sections have much less of an effect on the morphology of the grains, and hence the amorphous grains remain unaltered/intact. On the other hand, harsh chemicals used in chemical separation method could lead to the destruction of presolar grains, especially amorphous grains (disordered structure) in comparison to crystalline ones (ordered crystals). Limited efforts have been put into an in situ search of SiC within meteorite sections, and no morphological studies exist for them as of yet. Nonetheless, simulation in the present study indicates amorphization of ice-mantle SiC through GCR interactions, and hunting for these amorphous grains through in situ searches in future would be desirable. As the ice thickness or the density increases, the GCR loses more energy and increases the capacity of destruction. Introduction of Si and C from the core in this ice mantle may also increase the density of the ice mantle; however, this