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Mock halo catalogs: assigning unresolved halo properties using correlations with local halo environment Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-26 Sujatha Ramakrishnan; Aseem Paranjape; Ravi K Sheth
Large-scale sky surveys require companion large volume simulated mock catalogs. To ensure precision cosmology studies are unbiased, the correlations in these mocks between galaxy properties and their large-scale environments must be realistic. Since galaxies are embedded in dark matter haloes, an important first step is to include such correlations – sometimes called assembly bias – for dark matter
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A spectroscopically confirmed Gaia-selected sample of 318 new young stars within ∼200 pc Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-26 Maruša Žerjal; Adam D Rains; Michael J Ireland; George Zhou; Jens Kammerer; Alex Wallace; Brendan J Orenstein; Thomas Nordlander; Harrison Abbot; Seo-Won Chang
In the Gaia era, the majority of stars in the Solar neighbourhood have parallaxes and proper motions precisely determined while spectroscopic age indicators are still missing for a large fraction of low-mass young stars. In this work we select 756 overluminous late K and early M young star candidates in the southern sky and observe them over 64 nights with the ANU 2.3m Telescope at Siding Spring Observatory
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Effect of Separate Initial Conditions on the Lyman-α Forest in Simulations Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-26 M A Fernandez; Simeon Bird; Phoebe Upton Sanderbeck
Using a set of high resolution simulations, we quantify the effect of species specific initial transfer functions on probes of the IGM via the Lyman-α forest. We focus on redshifts 2 − 6, after H i reionization. We explore the effect of these initial conditions on measures of the thermal state of the low density IGM: the curvature, Doppler width cutoff, and Doppler width distribution. We also examine
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An enquiry on the origins of N-rich stars in the inner Galaxy based on APOGEE chemical compositions Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-26 Shobhit Kisku; Ricardo P Schiavon; Danny Horta; Andrew Mason; J Ted Mackereth; Sten Hasselquist; D A Garcí a-Hernández; Dmitry Bizyaev; Joel R Brownstein; Richard R Lane; Dante Minniti; Kaike Pan; Alexandre Roman-Lopes
Recent evidence based on APOGEE data for stars within a few kpc of the Galactic centre suggests that dissolved globular clusters (GCs) contribute significantly to the stellar mass budget of the inner halo. In this paper we enquire into the origins of tracers of GC dissolution, N-rich stars, that are located in the inner 4 kpc of the Milky Way. From an analysis of the chemical compositions of these
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Gravitational redshifting of galaxies in the SPIDERS cluster catalogue Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-26 C T Mpetha; C A Collins; N Clerc; A Finoguenov; J A Peacock; J Comparat; D Schneider; R Capasso; S Damsted; K Furnell; A Merloni; N D Padilla; A Saro
Data from the SPectroscopic IDentification of ERosita Sources (SPIDERS) are searched for a detection of the gravitational redshifting of light from ∼20 000 galaxies in ∼2500 galaxy clusters using three definitions of the cluster centre: its Brightest Cluster Galaxy (BCG), the redMaPPer identified Central Galaxy (CG), or the peak of X-ray emission. Distributions of velocity offsets between galaxies
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Integral Field Spectroscopy of Luminous Infrared Main Sequence Galaxies at Cosmic Noon Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-26 L Hogan; D Rigopoulou; G E Magdis; M Pereira-Santaella; I García-Bernete; N Thatte; K Grisdale; J-S Huang
We present the results of an integral field spectroscopy survey of a sample of dusty (ultra) luminous infrared galaxies (U/LIRGs) at 2 < z < 2.5 using KMOS on the Very Large Telescope. The sample has been drawn from Herschel deep field surveys and benefits from ancillary multi-wavelength data. Our goal is to investigate the physical characteristics, kinematics and the drivers of star formation in the
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Feedback Factory: Multiple faint radio-jets detected in a cluster at z=2 Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-26 Boris S Kalita; Emanuele Daddi; Rosemary T Coogan; Ivan Delvecchio; Raphael Gobat; Francesco Valentino; Veronica Strazzullo; Evangelia Tremou; Carlos Gómez-Guijarro; David Elbaz; Alexis Finoguenov
We report the detection of multiple faint radio sources, that we identify as AGN-jets, within CLJ1449+0856 at z=2 using 3 GHz VLA observations. We study the effects of radio-jet based kinetic feedback at high redshifts, which has been found to be crucial in low redshift clusters to explain the observed thermodynamic properties of their ICM. We investigate this interaction at an epoch featuring high
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X-raying the galaxy pair Arp 41: no collision in NGC 1232 and three ultraluminous sources in NGC 1232A Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-26 Roberto Soria; Manfred W Pakull
We studied the apparent galaxy pair NGC 1232/NGC 1232A with Chandra, looking for evidence of interactions and collisions. We report that there is no cloud of diffuse emission in NGC 1232, contrary to previous claims in the literature. Instead, we find that the small “companion” galaxy NGC 1232A contains three ultraluminous X-ray sources with peak 0.3–10 keV luminosities above 1040 erg s−1 (assuming
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GAMA/DEVILS: Constraining the cosmic star-formation history from improved measurements of the 0.3–2.2 μm Extragalactic Background Light Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-26 Soheil Koushan; Simon P Driver; Sabine Bellstedt; Luke J Davies; Aaron S G Robotham; Claudia del P Lagos; Abdolhosein Hashemizadeh; Danail Obreschkow; Jessica E Thorne; Malcolm Bremer; B W Holwerda; Andrew M Hopkins; Matt J Jarvis; Malgorzata Siudek; Rogier A Windhorst
We present a revised measurement of the optical extragalactic background light (EBL), based on the contribution of resolved galaxies to the integrated galaxy light (IGL). The cosmic optical background radiation (COB), encodes the light generated by star-formation, and provides a wealth of information about the cosmic star formation history (CSFH). We combine wide and deep galaxy number counts from
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Testing the Turbulent Origin of the Stellar Initial Mass Function Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-26 Donghee G Nam; Christoph Federrath; Mark R Krumholz
Supersonic turbulence in the interstellar medium (ISM) is closely linked to the formation of stars, and hence many theories connect the stellar initial mass function (IMF) with the turbulent properties of molecular clouds. Here we test three turbulence-based IMF models (by Padoan & Nordlund 2002, Hennebelle & Chabrier 2008, and Hopkins 2012), which predict the relation between the high-mass slope (Γ)
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A fully-kinetic model for orphan gamma-ray flares in blazars Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-26 Emanuele Sobacchi; Joonas Nättilä; Lorenzo Sironi
Blazars emit a highly-variable non-thermal spectrum. It is usually assumed that the same non-thermal electrons are responsible for the IR-optical-UV emission (via synchrotron) and the gamma-ray emission (via inverse Compton). Hence, the light curves in the two bands should be correlated. Orphan gamma-ray flares (i.e., lacking a luminous low-frequency counterpart) challenge our theoretical understanding
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Absorption effects in the blazar’s γ-ray spectra due to luminous stars crossing the jet Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-26 W Bednarek; J Sitarek
γ-ray emission in active galaxies is likely produced within the inner jet, or in the close vicinity of the supermassive black hole (SMBH) at sub-parsec distances. γ rays have to pass through the surrounding massive stellar cluster which luminous stars can accidentally appear close to the observer’s line of sight. In such a case, soft radiation of massive stars can create enough target for transient
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Infrared emission of z ∼ 6 galaxies: AGN imprints Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-26 F Di Mascia; S Gallerani; C Behrens; A Pallottini; S Carniani; A Ferrara; P Barai; F Vito; T Zana
We investigate the infrared (IR) emission of high-redshift (z ∼ 6), highly star-forming (SFR > 100 M⊙ yr−1) galaxies, with/without Active Galactic Nuclei (AGN), using a suite of cosmological simulations featuring dust radiative transfer. Synthetic Spectral Energy Distributions (SEDs) are used to quantify the relative contribution of stars/AGN to dust heating. In dusty (Md ≳ 3 × 107 M⊙) galaxies, ≳
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Connecting turbulent velocities and magnetic fields in galaxy cluster simulations with active galactic nuclei jets Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-26 K Ehlert; R Weinberger; C Pfrommer; V Springel
The study of velocity fields of the hot gas in galaxy clusters can help to unravel details of microphysics on small-scales and to decipher the nature of feedback by active galactic nuclei (AGN). Likewise, magnetic fields as traced by Faraday rotation measurements (RMs) inform about their impact on gas dynamics as well as on cosmic ray production and transport. We investigate the inherent relationship
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Fanaroff-Riley classification of radio galaxies using group-equivariant convolutional neural networks. Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-26 Anna M M Scaife; Fiona Porter
Weight sharing in convolutional neural networks (CNNs) ensures that their feature maps will be translation-equivariant. However, although conventional convolutions are equivariant to translation, they are not equivariant to other isometries of the input image data, such as rotation and reflection. For the classification of astronomical objects such as radio galaxies, which are expected statistically
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Refractivity‐from‐Clutter Capable, Software‐Defined, Coherent‐on‐Receive Marine Radar Radio Sci. (IF 1.305) Pub Date : 2021-02-26 Joshua Compaleo; Caglar Yardim; Luyao Xu
Refractivity‐from‐Clutter (RFC) is a technique for remote sensing of the lowest portion of vertical atmospheric refractivity profile, particularly evaporation and surface‐based ducts. It uses the sea‐surface backscattered radar signal to estimate the ducting conditions. The Lower Atmospheric Propagation (LATPROP) radar is a software‐defined, coherent‐on‐receive remote sensing system built on a low‐cost
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Angular Superresolution Based on A Priori Information Radio Sci. (IF 1.305) Pub Date : 2021-01-18 B. Lagovsky; A. Samokhin; Y. Shestopalov
The results of theoretical studies and mathematical modeling indicate the possibility of obtaining the angular superresolution and its limits by using algebraic methods of imaging. The necessary algorithms are created on the basis of solution to inverse problems. The limiting levels of the achieved angular superresolution are found depending on the signal‐to‐noise ratio for objects of various types
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Optimizing Forward‐Looking Missile‐Borne BSAR Imaging With Convolutional Neural Network Radio Sci. (IF 1.305) Pub Date : 2021-02-03 Hongyin Shi; Yupeng Yang; Chunyang Lv; Jing Zhang; Jianwen Guo
During the guidance of the missile, the target needs to be positioned in real time. The detonating missile will look forward to the target area during the flight, and the imaging distance becomes closer as the missile approaches the target. The image quality of forward‐looking missile‐borne bistatic synthetic aperture radar (FM‐BSAR) deteriorates rapidly when the detonator enters a rapid dive stage
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Issue Information Radio Sci. (IF 1.305) Pub Date : 2021-02-25
No abstract is available for this article.
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Discovery of new mercury–manganese stars, including a fast rotator Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-19 González J, Nuñez N, Saffe C, et al.
ABSTRACTThe origin of mercury–manganese (HgMn) stars is still poorly understood and the statistical analysis of an extensive sample of well characterized objects would be very valuable. Nevertheless, the compilation of a clean and reliable list of all known HgMn stars, and complete characterization of those objects, is still a pending issue. We report the identification of 13 new HgMn stars from our
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On the possibility of dust acoustic waves over sunlit lunar surface Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-24 S K Mishra
The photoelectron sheath and floating fine positively charged dust particles constitute two-component dusty plasma in the sunlit lunar regolith's vicinity. By including the charge fluctuation into photoelectron-dust dynamics, the lunar exospheric plasma is proposed to support the propagation of long-wavelength dust acoustic (DA) modes. Using the standard approach based on the dynamical equations for
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High-resolution imaging follow-up of doubly imaged quasars Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-24 Anowar J Shajib; Eden Molina; Adriano Agnello; Peter R Williams; Simon Birrer; Tommaso Treu; Christopher D Fassnacht; Takahiro Morishita; Louis Abramson; Paul L Schechter; Lutz Wisotzki
We report upon three years of follow-up and confirmation of doubly imaged quasar lenses through imaging campaigns from 2016–2018 with the Near-Infrared Camera2 (NIRC2) on the W. M. Keck Observatory. A sample of 57 quasar lens candidates are imaged in adaptive-optics-assisted or seeing-limited K′-band observations. Out of these 57 candidates, 15 are confirmed as lenses. We form a sample of 20 lenses
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Compact groups from semi-analytical models of galaxy formation – II: Different assembly channels Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-24 E Díaz-Giménez; A Zandivarez; G A Mamon
We study the formation of over 6000 compact groups (CGs) of galaxies identified in mock redshift-space galaxy catalogues built from semi-analytical models of galaxy formation (SAMs) run on the Millennium Simulations. We select CGs of 4 members in our mock SDSS galaxy catalogues and, for each CG, we trace back in time the real-space positions of the most massive progenitors of their 4 galaxies. By analysing
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Dark Energy Survey internal consistency tests of the joint cosmological probes analysis with posterior predictive distributions Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-24 C Doux; E Baxter; P Lemos; C Chang; A Alarcon; A Amon; A Campos; A Choi; M Gatti; D Gruen; M Jarvis; N MacCrann; Y Park; J Prat; M M Rau; M Raveri; S Samuroff; J DeRose; W G Hartley; B Hoyle; M A Troxel; J Zuntz; T M C Abbott; M Aguena; S Allam; J Annis; S Avila; D Bacon; E Bertin; S Bhargava; D Brooks; D L Burke; M Carrasco Kind; J Carretero; R Cawthon; M Costanzi; L N da Costa; M E S Pereira; S Desai;
Beyond-ΛCDM physics or systematic errors may cause subsets of a cosmological data set to appear inconsistent when analyzed assuming ΛCDM. We present an application of internal consistency tests to measurements from the Dark Energy Survey Year 1 (DES Y1) joint probes analysis. Our analysis relies on computing the posterior predictive distribution (PPD) for these data under the assumption of ΛCDM. We
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The environment of QSO triplets at 1 ≲ z ≲ 1.5 Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-24 Marcelo C Vicentin; Pablo Araya-Araya; Laerte Sodré; Roderik Overzier; Eleazar R Carrasco; Hector Cuevas
We present an analysis of the environment of six QSO triplets at 1 ≲ z ≲ 1.5 by analyzing multiband (r, i, z, or g, r, i) images obtained with Megacam at the CFHT telescope, aiming to investigate whether they are associated or not with galaxy protoclusters. This was done by using photometric redshifts trained using the high accuracy photometric redshifts of the COSMOS2015 catalogue. To improve the
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Dust Transport in Protoplanetary Disks with Wind-driven Accretion Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-24 Zitao Hu; Xue-Ning Bai
It has recently been shown that the inner region of protoplanetary disks (PPDs) is governed by wind-driven accretion, and the resulting accretion flow showing complex vertical profiles. Such complex flow structures are further enhanced due to the Hall effect, especially when the background magnetic field is aligned with disk rotation. We investigate how such flow structures impact global dust transport
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Light Curve Calculations for Triple Microlensing Systems Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-24 Renkun Kuang; Shude Mao; Tianshu Wang; Weicheng Zang; Richard J Long
We present a method to compute the magnification of a finite source star lensed by a triple lens system based on the image boundary (contour integration) method. We describe a new procedure to obtain continuous image boundaries from solutions of the tenth-order polynomial obtained from the lens equation. Contour integration is then applied to calculate the image areas within the image boundaries, which
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Observations of a radio-bright, X-ray obscured GRS 1915+105 Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-24 S E Motta; J J E Kajava; M Giustini; D R A Williams; M Del Santo; R Fender; D A Green; I Heywood; L Rhodes; A Segreto; G Sivakoff; P A Woudt
The Galactic black hole transient GRS 1915+105 is famous for its markedly variable X-ray and radio behaviour, and for being the archetypal galactic source of relativistic jets. It entered an X-ray outburst in 1992 and has been active ever since. Since 2018 GRS 1915+105 has declined into an extended low-flux X-ray plateau, occasionally interrupted by multi-wavelength flares. Here we report the radio
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Dark matter halos of massive elliptical galaxies at z ∼ 0.2 are well described by the Navarro–Frenk–White profile Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-24 Anowar J Shajib; Tommaso Treu; Simon Birrer; Alessandro Sonnenfeld
We investigate the internal structure of elliptical galaxies at z ∼ 0.2 from a joint lensing–dynamics analysis. We model Hubble Space Telescope images of a sample of 23 galaxy–galaxy lenses selected from the Sloan Lens ACS (SLACS) survey. Whereas the original SLACS analysis estimated the logarithmic slopes by combining the kinematics with the imaging data, we estimate the logarithmic slopes only from
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The influence of photo-induced processes and charge transfer on carbon and oxygen in the lower solar atmosphere Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-24 R P Dufresne; G Del Zanna; N R Badnell
To predict line emission in the solar atmosphere requires models which are fundamentally different depending on whether the emission is from the chromosphere or the corona. At some point between the two regions, there must be a change between the two modelling regimes. Recent extensions to the coronal modelling for carbon and oxygen lines in the solar transition region have shown improvements in the
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Sufficiency of a Gaussian power spectrum likelihood for accurate cosmology from upcoming weak lensing surveys Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-24 Robin E Upham; Michael L Brown; Lee Whittaker
We investigate whether a Gaussian likelihood is sufficient to obtain accurate parameter constraints from a Euclid-like combined tomographic power spectrum analysis of weak lensing, galaxy clustering and their cross-correlation. Testing its performance on the full sky against the Wishart distribution, which is the exact likelihood under the assumption of Gaussian fields, we find that the Gaussian likelihood
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Damped perturbations in stellar systems: Genuine modes and Landau-damped waves Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-24 E V Polyachenko; I G Shukhman; O I Borodina
This research was stimulated by the recent studies of damping solutions in dynamically stable spherical stellar systems. Using the simplest model of the homogeneous stellar medium, we discuss nontrivial features of stellar systems. Taking them into account will make it possible to correctly interpret the results obtained earlier and will help to set up decisive numerical experiments in the future.
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The Completed SDSS-IV extended Baryon Oscillation Spectroscopic Survey: one thousand multi-tracer mock catalogues with redshift evolution and systematics for galaxies and quasars of the final data release Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-24 Cheng Zhao; Chia-Hsun Chuang; Julian Bautista; Arnaud de Mattia; Anand Raichoor; Ashley J Ross; Jiamin Hou; Richard Neveux; Charling Tao; Etienne Burtin; Kyle S Dawson; Sylvain de la Torre; Héctor Gil-Marín; Jean-Paul Kneib; Will J Percival; Graziano Rossi; Amélie Tamone; Jeremy L Tinker; Gong-Bo Zhao; Shadab Alam; Eva-Maria Mueller
We produce 1000 realizations of synthetic clustering catalogues for each type of the tracers used for the baryon acoustic oscillation and redshift space distortion analysis of the SDSS-IV extended Baryon Oscillation Spectroscopic Survey final data release (eBOSS DR16), covering the redshift range from 0.6 to 2.2, to provide reliable estimates of covariances matrices and test the robustness of the analysis
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A statistical measurement of the H i spin temperature in DLAs at cosmological distances Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-24 James R Allison
Evolution of the cosmic star formation rate (SFR) and molecular mass density is expected to be matched by a similarly strong evolution of the fraction of atomic hydrogen (H i) in the cold neutral medium (CNM). We use results from a recent commissioning survey for intervening 21-cm absorbers with the Australian Square Kilometre Array Pathfinder (ASKAP) to construct a Bayesian statistical model of the
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Did Sgr cause the vertical waves in the solar neighbourhood? Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-24 Morgan Bennett; Jo Bovy
The vertical distribution of stars in the solar neighbourhood is not in equilibrium but contains a wave signature in both density and velocity space originating from a perturbation. With the discovery of the phase-space spiral in Gaia data release 2, determining the origin of this perturbation has become even more urgent. We develop and test a fast method for calculating the perturbation from a passing
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Unveiling the Planet Population at Birth Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-24 James G Rogers; James E Owen
The radius distribution of small, close-in exoplanets has recently been shown to be bimodal. The photoevaporation model predicted this bimodality. In the photoevaporation scenario, some planets are completely stripped of their primordial H/He atmospheres, whereas others retain them. Comparisons between the photoevaporation model and observed planetary populations have the power to unveil details of
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Hot and counter-rotating star-forming disk galaxies in IllustrisTNG and their real-world counterparts Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-24 Shengdong Lu; Dandan Xu; Yunchong Wang; Yanmei Chen; Ling Zhu; Shude Mao; Volker Springel; Jing Wang; Mark Vogelsberger; Lars Hernquist
A key feature of a large population of low-mass, late-type disk galaxies are star-forming disks with exponential light distributions. They are typically also associated with thin and flat morphologies, blue colours, and dynamically cold stars moving along circular orbits within co-planar thin gas disks. However, the latter features do not necessarily always imply the former, in fact, a variety of different
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Conditions in the WR 140 wind-collision region revealed by the 1.083-μm He i line profile. Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-23 Peredur M Williams; Watson P Varricatt; André-Nicolas Chené; Michael F Corcoran; Ted R Gull; Kenji Hamaguchi; Anthony F J Moffat; Andrew M T Pollock; Noel D Richardson; Christopher M P Russell; Andreas A C Sander; Ian R Stevens; Gerd Weigelt
We present spectroscopy of the P Cygni profile of the 1.083-μm He i line in the WC7 + O5 colliding-wind binary (CWB) WR 140 (HD 193793), observed in 2008, before its periastron passage in 2009, and in 2016–17, spanning the subsequent periastron passage. Both absorption and emission components showed strong variations. The variation of the absorption component as the O5 star was occulted by the wind-collision
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The nearby spiral density-wave structure of the Galaxy: line-of-sight velocities of the Gaia DR2 OB stars Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-23 Evgeny Griv; Michael Gedalin; Ing-Guey Jiang
Distances and line-of-sight velocities of 964 Gaia DR2 OB stars of Xu et al. within 3 kpc from the Sun and 500 pc from the Galactic mid-plane with accuracies of <50 per cent are selected. The data are used to find small systematic departures of velocities from the mean circular motion for the stars in the solar neighborhood due to the spiral compression-type (Lin–Shu-type) waves, or spiral density
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Feasibility Study of a High‐Resolution Shallow Surface Penetration Radar for Space Application Radio Sci. (IF 1.305) Pub Date : 2021-01-17 P. Song; S. Gogineni; I. A. Galkin; J. Volakis; J. M. Soderblom; A. G. Hayes; B. W. Reinisch; R. H. Giles; R. Sood; H.‐L. Zhang; D. Braaten; H. J. Melosh; L. Bruzzone; S. B. Venkatakrishnan; J. B. Yan; C. R. O'Neil
We modified and justified the radar equation for ground penetration by including the backscattering effect. We propose a strawman system on an orbiter 50 km above the surface based on lunar conditions. The Tightly coupled dipole arrays antenna substantially reduces the size and mass and consists of an array with 8 × 8 cells on a light weight plate that is 1.62‐m2 wide with cells 0.25‐m high providing
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A Local Split‐Step Wavelet Method for the Long Range Propagation Simulation in 2D Radio Sci. (IF 1.305) Pub Date : 2021-01-21 Thomas Bonnafont; Rémi Douvenot; Alexandre Chabory
Modeling long‐range propagation of electromagnetic waves is necessary to study the performance of systems, for applications such as radar or navigation. Such models generally rely on split‐step Fourier (SSF) because large mesh sizes can be used. The split‐step wavelet method (SSW) is a recently developed method allowing to perform the same simulations as with SSF but in a shorter computation time.
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Satellite Observations of Strong Plasma Wave Emissions With Frequency Shifts Induced by an Engine Burn From the Cygnus Spacecraft Radio Sci. (IF 1.305) Pub Date : 2021-01-17 Paul A. Bernhardt; Michael K. Griffin; William C. Bougas; Andrew D. Howarth; H. Gordon James; Carl L. Siefring; Stanley J. Briczinski
A new discovery was made using the radio receiver instrument on the Canadian enhanced polar outflow probe (e‐POP) showing that strong plasma wave emissions (SPWE) are seen near 17 kHz and 300 Hz. The frequency of these emissions are affected by small injections of neutral gas from the Cygnus spacecraft. The technique of using a 150 g/s thruster to change frequencies and intensities of plasma waves
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Strong Amplification of ELF/VLF Signals in Space Using Neutral Gas Injections From a Satellite Rocket Engine Radio Sci. (IF 1.305) Pub Date : 2021-01-29 Paul A. Bernhardt; William C. Bougas; Michael K. Griffin; Chris Watson; Richard B. Langley; Andrew D. Howarth; H. Gordon James; Carl L. Siefring; Gareth W. Perry; Joseph. D. Huba; Robert C. Moore; Morris. B. Cohen; Mark. Gołkowski
The first demonstration of rocket exhaust driven amplification (REDA) of whistler mode waves occurred on May 26, 2020 by transferring energy from pickup ions in a rocket exhaust plume to EM waves. The source of coherent VLF waves was the Navy NML Transmitter at 25.2 kHz located in LaMoure, North Dakota. The topside ionosphere at 480 km altitude became an amplifying medium with a 60 s firing of the
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The warm-up phase in massive star-forming cores around RCW 120 Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-22 M S Kirsanova; S V Salii; S V Kalenskii; D S Wiebe; A M Sobolev; P A Boley
We study molecular emission in a massive condensation at the border of the H ii region RCW 120, paying particular attention to the Core 1 and Core 2 objects, the most massive fragments of the condensation found previously by ALMA. The latter fragment was previously suggested to host a high-mass analogue of Class 0 young stellar object. We present spectra of molecular emission in the 1 mm range made
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On the origin of GeV spectral break for Fermi blazars: 3C 454.3 Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-22 Shi-Ju Kang; Yong-Gang Zheng; Qingwen Wu; Liang Chen; Yue Yin
The GeV break in spectra of the blazar 3C 454.3 is a special observation feature that has been discovered by the Fermi-LAT. The origin of the GeV break in the spectra is still under debate. In order to explore the possible source of GeV spectral break in 3C 454.3, a one-zone homogeneous leptonic jet model, as well as the McFit technique are utilized for fitting the quasi-simultaneous multi-waveband
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Time Delay Lens modelling Challenge Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-22 X Ding; T Treu; S Birrer; G C-F Chen; J Coles; P Denzel; M Frigo; A Galan; P J Marshall; M Millon; A More; A J Shajib; D Sluse; H Tak; D Xu; M W Auger; V Bonvin; H Chand; F Courbin; G Despali; C D Fassnacht; D Gilman; S Hilbert; S R Kumar; J Y-Y Lin; J W Park; P Saha; S Vegetti; L Van de Vyvere; L L R Williams
In recent years, breakthroughs in methods and data have enabled gravitational time delays to emerge as a very powerful tool to measure the Hubble constant H0. However, published state-of-the-art analyses require of order 1 year of expert investigator time and up to a million hours of computing time per system. Furthermore, as precision improves, it is crucial to identify and mitigate systematic uncertainties
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Supermassive black holes in cosmological simulations I: MBH − M⋆ relation and black hole mass function Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-22 Mélanie Habouzit; Yuan Li; Rachel S Somerville; Shy Genel; Annalisa Pillepich; Marta Volonteri; Romeel Davé; Yetli Rosas-Guevara; Stuart McAlpine; Sébastien Peirani; Lars Hernquist; Daniel Anglés-Alcázar; Amy Reines; Richard Bower; Yohan Dubois; Dylan Nelson; Christophe Pichon; Mark Vogelsberger
The past decade has seen significant progress in understanding galaxy formation and evolution using large-scale cosmological simulations. While these simulations produce galaxies in overall good agreement with observations, they employ different sub-grid models for galaxies and supermassive black holes (BHs). We investigate the impact of the sub-grid models on the BH mass properties of the Illustris
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Chondrules from high-velocity collisions: thermal histories and the agglomeration problem Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-22 Nick Choksi; Eugene Chiang; Harold C Connolly; Zack Gainsforth; Andrew J Westphal
We assess whether chondrules, once-molten mm-sized spheres filling the oldest meteorites, could have formed from super-km/s collisions between planetesimals in the solar nebula. High-velocity collisions release hot and dense clouds of silicate vapor which entrain and heat chondrule precursors. Thermal histories of CB chondrules are reproduced for colliding bodies ∼10–100 km in radius. The slower cooling
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Evolution of Earth-like extended exospheres orbiting solar-like stars Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-22 Ada Canet; Ana I Gómez de Castro
Recent observations of the Earth’s exosphere revealed the presence of an extended hydrogenic component that could reach distances beyond 40 planetary radii. Detection of similar extended exospheres around Earth-like exoplanets could reveal crucial facts in terms of habitability. The presence of these rarified hydrogen envelopes is extremely dependent of the planetary environment, dominated by the ionizing
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Segmentation of spectroscopic images of the low solar atmosphere by the Self Organizing Map technique Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-22 F Schilliro; P Romano
We describe the application of Semantic Segmentation by using the Self Organizing Map technique to an high spatial and spectral resolution dataset acquired along the Hα line at 656.28 nm by the Interferometric Bi-dimensional Spectrometer installed at the focus plane of the Dunn Solar Telescope. This machine learning approach allowed us to identify several features corresponding to the main structures
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A Metasurface Based Gain Enhanced Dual Band Patch Antenna Using SRRs With Defected Ground Structure Radio Sci. (IF 1.305) Pub Date : 2021-01-27 Diptiranjan Samantaray; Somak Bhattacharyya
This study proposes a metasurface (MS) based high performance antenna in which the radiating patch is embedded with split ring resonators in its square slots. The slotted corner cut rectangular patch antenna with defected ground plane and the MS are placed together in the same plane. The designed prototype operates over dual frequencies with impedance bandwidths (S11 < −10 dB) of 4.02% and 28.24% at
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The properties and environment of very young galaxies in the local Universe Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-20 M Trevisan; G A Mamon; T X Thuan; F Ferrari; L S Pilyugin; A Ranjan
In the local Universe, there is a handful of dwarf compact star-forming galaxies with extremely low oxygen abundances. It has been proposed that they are young, having formed a large fraction of their stellar mass during their last few hundred Myr. However, little is known about the fraction of young stellar populations in more massive galaxies. In a previous article, we analyzed 280 000 SDSS spectra
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Multi–wavelength flare observations of the blazar S5 1803+784 Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-20 R Nesci; S Cutini; C Stanghellini; F Martinelli; A Maselli; V M Lipunov; V Kornilov; R R Lopez; A Siviero; M Giroletti; M Orienti
The radio, optical, and γ-ray light curves of the blazar S5 1803+784, from the beginning of the Fermi Large Area Telescope (LAT) mission in August 2008 until December 2018, are presented. The aim of this work is to look for correlations among different wavelengths useful for further theoretical studies. We analyzed all the data collected by Fermi LAT for this source, taking into account the presence
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Radio and optical observations of the possible AE Aqr twin, LAMOST J024048.51+195226.9 Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-20 M L Pretorius; D M Hewitt; P A Woudt; R P Fender; I Heywood; C Knigge; J C A Miller-Jones; D A H Buckley; H L Worters; S B Potter; D R A Williams
It was recently proposed that the cataclysmic variable (CV) LAMOST J024048.51+195226.9 may be a twin to the unique magnetic propeller system AE Aqr. If this is the case, two predictions are that it should display a short period white dwarf spin modulation, and that it should be a bright radio source. We obtained follow-up optical and radio observations of this CV, in order to see if this holds true
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Determining the range of validity of quasar X-ray and UV flux measurements for constraining cosmological model parameters Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-20 Narayan Khadka; Bharat Ratra
We use six different cosmological models to study the recently-released compilation of X-ray and UV flux measurements of 2038 quasars (QSOs) which span the redshift range 0.009 ≤ z ≤ 7.5413. We find, for the full QSO data set, that the parameters of the X-ray and UV luminosities LX − LUV relation used to standardized these QSOs depend on the cosmological model used to determine these parameters, i
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The delay time distribution of Type-Ia supernovae in galaxy clusters: the impact of extended star-formation histories Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-20 Jonathan Freundlich; Dan Maoz
The delay time distribution (DTD) of Type-Ia supernovae (SNe Ia) is important for understanding chemical evolution, SN Ia progenitors, and SN Ia physics. Past estimates of the DTD in galaxy clusters have been deduced from SN Ia rates measured in cluster samples observed at various redshifts, corresponding to different time intervals after a presumed initial brief burst of star formation. A recent analysis
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The Case for Thermalization as a Contributor to the [CII] Deficit Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-20 Jessica Sutter; Daniel A Dale; Karin Sandstrom; J D T Smith; Alberto Bolatto; Mederic Boquien; Daniela Calzetti; Kevin V Croxall; Ilse De Looze; Maude Galametz; Brent A Groves; George Helou; Rodrigo Herrera-Camus; Leslie K Hunt; Robert C Kennicutt; Eric W Pelligrini; Christine Wilson; Mark G Wolfire
The [CII] deficit, which describes the observed decrease in the ratio of [CII] 158 μm emission to continuum infrared emission in galaxies with high star formation surface densities, places a significant challenge to the interpretation of [CII] detections from across the observable universe. In an attempt to further decode the cause of the [CII] deficit, the [CII] and dust continuum emission from 18
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Erratum: Evaluating hydrodynamical simulations with green valley galaxies Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-19 Angthopo J, Negri A, Ferreras I, et al.
errata, addendagalaxies: evolutiongalaxies: formationgalaxies: interactionsgalaxies: stellar content
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Dispersion measure distributions of fast radio bursts due to the intergalactic medium Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-04 Medlock I, Cen R.
ABSTRACTUtilizing cosmological hydrodynamic simulations, we quantify the distributions of the dispersion measure (DM) of fast radio bursts (FRBs). We examine the contributions of cold, warm-hot, and hot gas to the total DM. We find that the hot gas component (T > 107K), on average, makes a minor contribution ($\le 5{{\ \rm per\ cent}}$) to the overall DM. Cold (T < 105K) and warm-hot (T = 105 − 107K)
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A stripped-companion origin for Be stars: clues from the putative black holes HR 6819 and LB-1 Mon. Not. R. Astron. Soc. (IF 5.356) Pub Date : 2021-02-03 El-Badry K, Quataert E.
ABSTRACTHR 6819 is a bright (V = 5.36), blue star recently proposed to be a triple containing a detached black hole (BH). We show that the system is a binary and does not contain a BH. Using spectral decomposition, we disentangle the observed composite spectra into two components: a rapidly rotating Be star and a slowly rotating B star with low surface gravity (log g ≈ 2.75). Both stars show periodic
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