- ID:
- ivo://CDS.VizieR/J/A+A/550/A53
- Title:
- Public code ARoME for modeling the RM effect
- Short Name:
- J/A+A/550/A53
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Rossiter-McLaughlin (hereafter RM) effect is a key tool for measuring the projected spin-orbit angle between stellar spin axes and orbits of transiting planets. However, the measured radial velocity (RV) anomalies produced by this effect are not intrinsic and depend on both instrumental resolution and data reduction routines. Using inappropriate formulas to model the RM effect introduces biases, at least in the projected velocity Vsini compared to the spectroscopic value. Currently, only the iodine cell technique has been modeled, which corresponds to observations done by, e.g., the HIRES spectrograph of the Keck telescope. In this paper, we provide a simple expression of the RM effect specially designed to model observations done by the Gaussian fit of a cross-correlation function (CCF) as in the routines performed by the HARPS team. We derived also a new analytical formulation of the RV anomaly associated to the iodine cell technique. For both formulas, we modeled the subplanet mean velocity v_p and dispersion beta_p accurately taking the rotational broadening on the subplanet profile into account. We compare our formulas adapted to the CCF technique with simulated data generated with the numerical software SOAP-T and find good agreement up to Vsini<20km/s. In contrast, the analytical models simulating the two different observation techniques can disagree by about 10sigma in Vsini for large spin-orbit misalignments. It is thus important to apply the adapted model when fitting data.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/424/2832
- Title:
- Pulsars in {gamma}-ray sources
- Short Name:
- J/MNRAS/424/2832
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Machine learning, algorithms designed to extract empirical knowledge from data, can be used to classify data, which is one of the most common tasks in observational astronomy. In this paper, we focus on Bayesian data classification algorithms using the Gaussian mixture model and show two applications in pulsar astronomy. After reviewing the Gaussian mixture model and the related expectation-maximization algorithm, we present a data classification method using the Neyman-Pearson test. To demonstrate the method, we apply the algorithm to two classification problems. First, it is applied to the well-known period-period derivative diagram. Our second example is to calculate the likelihood of unidentified Fermi point sources being pulsars.
- ID:
- ivo://CDS.VizieR/J/A+A/584/A80
- Title:
- Pulsation model data for delta Cep and eta Aql
- Short Name:
- J/A+A/584/A80
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The parallax of pulsation, and its implementations such as the Baade-Wesselink method and the infrared surface brightness technique, is an elegant method to determine distances of pulsating stars in a quasi-geometrical way. However, these classical implementations in general only use a subset of the available observational data. Freedman & Madore (2010ApJ...719..335F) suggested a more physical approach in the implementation of the parallax of pulsation in order to treat all available data. We present a global and model-based parallax-of-pulsation method that enables including any type of observational data in a consistent model fit, the SpectroPhoto-Interferometric modeling of Pulsating Stars (SPIPS). We implemented a simple model consisting of a pulsating sphere with a varying effective temperature and a combination of atmospheric model grids to globally fit radial velocities, spectroscopic data, and interferometric angular diameters. We also parametrized (and adjusted) the reddening and the contribution of the circumstellar envelopes in the near-infrared photometric and interferometric measurements.
- ID:
- ivo://CDS.VizieR/J/ApJ/833/244
- Title:
- Pulse profiles for simulated thermonuclear bursts
- Short Name:
- J/ApJ/833/244
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The equation of state of cold supra-nuclear-density matter, such as in neutron stars, is an open question in astrophysics. A promising method for constraining the neutron star equation of state is modeling pulse profiles of thermonuclear X-ray burst oscillations from hot spots on accreting neutron stars. The pulse profiles, constructed using spherical and oblate neutron star models, are comparable to what would be observed by a next-generation X-ray timing instrument like ASTROSAT, NICER, or a mission similar to LOFT. In this paper, we showcase the use of an evolutionary optimization algorithm to fit pulse profiles to determine the best-fit masses and radii. By fitting synthetic data, we assess how well the optimization algorithm can recover the input parameters. Multiple Poisson realizations of the synthetic pulse profiles, constructed with 1.6 million counts and no background, were fitted with the Ferret algorithm to analyze both statistical and degeneracy-related uncertainty and to explore how the goodness of fit depends on the input parameters. For the regions of parameter space sampled by our tests, the best-determined parameter is the projected velocity of the spot along the observer's line of sight, with an accuracy of <=3% compared to the true value and with <=5% statistical uncertainty. The next best determined are the mass and radius; for a neutron star with a spin frequency of 600Hz, the best-fit mass and radius are accurate to <=5%, with respective uncertainties of <=7% and <=10%. The accuracy and precision depend on the observer inclination and spot colatitude, with values of ~1% achievable in mass and radius if both the inclination and colatitude are >~60deg.
- ID:
- ivo://CDS.VizieR/J/ApJ/870/1
- Title:
- PUSH CCSN to explosions in spherical symmetry. II.
- Short Name:
- J/ApJ/870/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In a previously presented proof-of-principle study, we established a parameterized spherically symmetric explosion method (PUSH) that can reproduce many features of core-collapse supernovae (CCSN). The present paper goes beyond a specific application that is able to reproduce observational properties of SN1987A and performs a systematic study of an extensive set of nonrotating, solar metallicity stellar progenitor models in the mass range from 10.8 to 120M_{sun}_. This includes the transition from neutron stars to black holes as the final result of the collapse of massive stars, and the relation of the latter to supernovae, possibly faint supernovae, and failed supernovae. We discuss the explosion properties of all models and predict remnant mass distributions within this approach. The present paper provides the basis for extended nucleosynthesis predictions in a forthcoming paper to be employed in galactic evolution models.
- ID:
- ivo://CDS.VizieR/J/ApJ/870/2
- Title:
- PUSH CCSN to explosions in spherical symmetry. III.
- Short Name:
- J/ApJ/870/2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In a previously presented proof-of-principle study, we established a parameterized spherically symmetric explosion method (PUSH) that can reproduce many features of core-collapse supernovae (CCSNe) for a wide range of pre-explosion models. The method is based on the neutrino-driven mechanism and follows collapse, bounce, and explosion. There are two crucial aspects of our model for nucleosynthesis predictions. First, the mass cut and explosion energy emerge simultaneously from the simulation (determining, for each stellar model, the amount of Fe-group ejecta). Second, the interactions between neutrinos and matter are included consistently (setting the electron fraction of the innermost ejecta). In the present paper, we use the successful explosion models from Paper II (Ebinger+, 2019, J/ApJ/870/1) that include two sets of pre-explosion models at solar metallicity, with combined masses between 10.8 and 120M_{sun}_. We perform systematic nucleosynthesis studies and predict detailed isotopic yields. The resulting ^56^Ni ejecta are in overall agreement with observationally derived values from normal CCSNe. The Fe-group yields are also in agreement with derived abundances for metal-poor star HD84937. We also present a comparison of our results with observational trends in alpha element to iron ratios.
- ID:
- ivo://CDS.VizieR/J/A+A/616/A147
- Title:
- Python Mie Doubling-Adding Programme
- Short Name:
- J/A+A/616/A147
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- PyMieDAP (the Python Mie Doubling-Adding Programme) is a Python-based tool for computing the total linearly and circularly polarized fluxes of incident unpolarized sunlight or starlight that is reflected by solar system planets or moons, respectively, or by exoplanets at a range of wavelengths. The radiative transfer computations are based on an doubling-adding Fortran algorithm and fully include polarization for all orders of scattering. The model (exo)planets are described by a model atmosphere composed of a stack of homogeneous layers containing gas and/or aerosol and/or cloud particles bounded below by an isotropically depolarizing surface (that is optionally black). The reflected light can be computed spatially resolved and/or disk-integrated. Spatially resolved signals are mostly representative for observations of solar system planets (or moons), while disk-integrated signals are mostly representative for exoplanet observations. PyMieDAP is modular and flexible, and allows users to adapt and optimize the code according to their needs. PyMieDAP keeps options open for connections with external programs and for future additions and extensions. In this paper, we describe the radiative transfer algorithm that PyMieDAP is based on and the principal functionalities of the code. We also provide benchmark results of PyMieDAP that can be used for testing its installation and for comparison with other codes. PyMieDAP is available online under the GNU GPL license at http://gitlab.com/loic.cg.rossi/pymiedap
- ID:
- ivo://CDS.VizieR/J/ApJ/728/26
- Title:
- QSO selection based on photometric variability
- Short Name:
- J/ApJ/728/26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We develop a method for separating quasars from other variable point sources using Sloan Digital Sky Survey (SDSS) Stripe 82 light-curve data for ~10000 variable objects. To statistically describe quasar variability, we use a damped random walk (DRW) model parametrized by a damping timescale, {tau}, and an asymptotic amplitude (structure function), SF_{infinite}_. With the aid of an SDSS spectroscopically confirmed quasar sample, we demonstrate that variability selection in typical extragalactic fields with low stellar density can deliver complete samples with reasonable purity (or efficiency, E). Compared to a selection method based solely on the slope of the structure function, the inclusion of the {tau} information boosts E from 60% to 75% while maintaining a highly complete sample (98%) even in the absence of color information. For a completeness of C=90%, E is boosted from 80% to 85%. Conversely, C improves from 90% to 97% while maintaining E=80% when imposing a lower limit on {tau}. With the aid of color selection, the purity can be further boosted to 96%, with C=93%. Hence, selection methods based on variability will play an important role in the selection of quasars with data provided by upcoming large sky surveys, such as Pan-STARRS and the Large Synoptic Survey Telescope (LSST). In summary, given an adequate survey cadence, photometric variability provides an even better method than color selection for separating quasars from stars.
- ID:
- ivo://CDS.VizieR/J/A+A/366/565
- Title:
- Radial oscillations of relativistic stars
- Short Name:
- J/A+A/366/565
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new survey of the radial oscillation modes of neutron stars. This study complements and corrects earlier studies of radial oscillations. We present an extensive list of frequencies for the most common equations of state and some more recent ones. In order to check the accuracy, we use two different numerical schemes which yield the same results. The stimulation for this work comes from the need of the groups that evolve the full nonlinear Einstein equations to have reliable results from perturbation theory for comparison.
- ID:
- ivo://CDS.VizieR/J/AJ/156/82
- Title:
- Radial velocity characterization of TESS planets
- Short Name:
- J/AJ/156/82
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Transiting Exoplanet Survey Satellite (TESS) will conduct a two-year wide-field survey searching for transiting planets around bright stars. Many TESS discoveries will be amenable to mass characterization via ground-based radial velocity measurements with any of a growing suite of existing and anticipated velocimeters in the optical and near-infrared. In this study we present an analytical formalism to compute the number of radial velocity (RV) measurements - and hence the total observing time-required to characterize RV planet masses with the inclusion of either a white or correlated noise activity model. We use our model to calculate the total observing time required to measure all TESS planet masses from the expected TESS planet yield while relying on our current understanding of the targeted stars, stellar activity, and populations of unseen planets that inform the expected RV precision. We also present specialized calculations applicable to a variety of interesting subsets of TESS planets including the characterization of 50 planets smaller than 4 Earth radii, which is expected to take as little as 60 nights of observation. However, the efficient RV characterization of such planets requires a priori knowledge of the "best" targets, which we argue can be identified prior to the conclusion of the TESS planet search based on our calculations. Our results highlight the comparable performance of optical and near-IR spectrographs for most planet populations except for Earths and temperate TESS planets, which are more efficiently characterized in the near-IR. Lastly, we present an online tool to the community to compute the total observing times required to detect any transiting planet using a user-defined spectrograph (RVFC; http://maestria.astro.umontreal.ca/rvfc).
