RAS_WEB (Page 4,385)

Shaping Asteroids with Genetic Evolution (SAGE). (arXiv:1904.08940v1 [astro-ph.EP]) <a href="http://arxiv.org/find/astro-ph/1/au:+Bartczak_P/0/1/0/all/0/1">P. Bartczak</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dudzinski_G/0/1/0/all/0/1">G. Dudzi&#x144;ski</a> In this work we present SAGE (Shaping Asteroid models using Genetic Evolution) asteroid modelling algorithm based solely on photometric lightcurve data. It produces non-convex shapes, rotation axes orientati and rotational periods of asteroids. The main concept behind a genetic evolution algorithm is to produce random populations of shapes and spin orientations by mutating a seed shape and iterating the process until it converges to a stable global minimum. To test SAGE we have performed tes on five artificial shapes. We have also modelled (433) Eros and (9) Meti asteroids, as groundRead More →

The Supersonic Project: Shining Light on SIGOs – a New Formation Channel for Globular Clusters. (arXiv:1904.08941v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Chiou_Y/0/1/0/all/0/1">Yeou S. Chiou</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Naoz_S/0/1/0/all/0/1">Smadar Naoz</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Burkhart_B/0/1/0/all/0/1">Blakesley Burkhart</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Marinacci_F/0/1/0/all/0/1">Federico Marinacci</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Vogelsberger_M/0/1/0/all/0/1">Mark Vogelsberger</a> Supersonically induced gas objects (SIGOs) with little to no dark matter component are predicted to exist in patches of the Universe with non-negligible relative velocity between baryons and the dark matter at the time of recombination. Using {sc arepo} hydrodynamic simulations we find that the gas densities inside these objects are high enough to allow stars to form. An estimate of the luminosity of the first star clusters formed within these SIGOsRead More →

Anatomy of a Cooling Flow: The Feedback Response to Pure Cooling in the Core of the Phoenix Cluster. (arXiv:1904.08942v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+McDonald_M/0/1/0/all/0/1">M. McDonald</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+McNamara_B/0/1/0/all/0/1">B. R. McNamara</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Voit_G/0/1/0/all/0/1">G. M. Voit</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bayliss_M/0/1/0/all/0/1">M. Bayliss</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Benson_B/0/1/0/all/0/1">B. A. Benson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Brodwin_M/0/1/0/all/0/1">M. Brodwin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Canning_R/0/1/0/all/0/1">R. E. A. Canning</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Florian_M/0/1/0/all/0/1">M. K. Florian</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Garmire_G/0/1/0/all/0/1">G. P. Garmire</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gaspari_M/0/1/0/all/0/1">M. Gaspari</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gladders_M/0/1/0/all/0/1">M. D. Gladders</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hlavacek_Larrondo_J/0/1/0/all/0/1">J. Hlavacek-Larrondo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kara_E/0/1/0/all/0/1">E. Kara</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Reichardt_C/0/1/0/all/0/1">C. L. Reichardt</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Russell_H/0/1/0/all/0/1">H. R. Russell</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Saro_A/0/1/0/all/0/1">A. Saro</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sharon_K/0/1/0/all/0/1">K. Sharon</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Somboonpanyakul_T/0/1/0/all/0/1">T. Somboonpanyakul</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tremblay_G/0/1/0/all/0/1">G. R. Tremblay</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Weeren_R/0/1/0/all/0/1">R. J. van Weeren</a> We present new, deep observations of the Phoenix cluster from the ChandraRead More →

Radio spectra and sizes of ALMA-identified submillimetre galaxies: evidence of age-related spectral curvature and cosmic ray diffusion?. (arXiv:1904.08944v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Thomson_A/0/1/0/all/0/1">A.P. Thomson</a> (JBCA &amp; Durham), <a href="http://arxiv.org/find/astro-ph/1/au:+Smail_I/0/1/0/all/0/1">Ian Smail</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Swinbank_A/0/1/0/all/0/1">A.M. Swinbank</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Simpson_J/0/1/0/all/0/1">J.M. Simpson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Arumugam_V/0/1/0/all/0/1">V. Arumugam</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Stach_S/0/1/0/all/0/1">S. Stach</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Murphy_E/0/1/0/all/0/1">E.J. Murphy</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rujopakarn_W/0/1/0/all/0/1">W. Rujopakarn</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Almaini_O/0/1/0/all/0/1">O. Almaini</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+An_F/0/1/0/all/0/1">F. An</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Blain_A/0/1/0/all/0/1">A.W. Blain</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chen_C/0/1/0/all/0/1">C.C. Chen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cooke_E/0/1/0/all/0/1">E.A. Cooke</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dudzeviciute_U/0/1/0/all/0/1">U. Dudzeviciute</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Edge_A/0/1/0/all/0/1">A.C. Edge</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Farrah_D/0/1/0/all/0/1">D. Farrah</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gullberg_B/0/1/0/all/0/1">B. Gullberg</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hartley_W/0/1/0/all/0/1">W. Hartley</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ibar_E/0/1/0/all/0/1">E. Ibar</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Maltby_D/0/1/0/all/0/1">D. Maltby</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Michalowski_M/0/1/0/all/0/1">M.J. Michalowski</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Simpson_C/0/1/0/all/0/1">C. Simpson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Werf_P/0/1/0/all/0/1">P. van der Werf</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wardlow_J/0/1/0/all/0/1">J.L. Wardlow</a> We analyse the multi-frequency radio spectral properties of $41$Read More →

X-Ray Spectral Model from Clumpy Torus and Its Application to Circinus Galaxy. (arXiv:1904.08945v1 [astro-ph.HE]) <a href="http://arxiv.org/find/astro-ph/1/au:+Tanimoto_A/0/1/0/all/0/1">Atsushi Tanimoto</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ueda_Y/0/1/0/all/0/1">Yoshihiro Ueda</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Odaka_H/0/1/0/all/0/1">Hirokazu Odaka</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kawaguchi_T/0/1/0/all/0/1">Toshihiro Kawaguchi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fukazawa_Y/0/1/0/all/0/1">Yasushi Fukazawa</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kawamuro_T/0/1/0/all/0/1">Taiki Kawamuro</a> We construct an X-ray spectral model from the clumpy torus in an active galactic nucleus (AGN), designated as “XCLUMPY”, utilizing the Monte Carlo simulation for Astrophysics and Cosmology framework (MONACO: Odaka et al. 2011, 2016). The adopted geometry of the torus is the same as that in Nenkova et al. (2008), who assume a power law distribution of clumps in the radial direction and a normal distribution in the elevation direction. We investigateRead More →

Rapid Luminosity Decline and Subsequent Reformation of the Innermost Dust Distribution in the Changing-look AGN Mrk 590. (arXiv:1904.08946v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Kokubo_M/0/1/0/all/0/1">Mitsuru Kokubo</a> (Tohoku University), <a href="http://arxiv.org/find/astro-ph/1/au:+Minezaki_T/0/1/0/all/0/1">Takeo Minezaki</a> (The University of Tokyo) We examined long-term optical/near-infrared (NIR) flux variability of a “changing-look” active galactic nucleus (AGN) Mrk 590 between 1998 and 2007. Multi-band multi-epoch optical/NIR photometry data from the SDSS Stripe 82 database and the Multicolor Active Galactic Nuclei Monitoring (MAGNUM) project reveal that Mrk 590 experienced a sudden luminosity decrease during the period from 2000 to 2001. Detection of dust reverberation lag signals between V- and K-band light curves obtained by the MAGNUM project duringRead More →

Atomic Modeling of Photoionization Fronts in Nitrogen Gas. (arXiv:1904.08947v1 [astro-ph.SR]) <a href="http://arxiv.org/find/astro-ph/1/au:+Gray_W/0/1/0/all/0/1">William J. Gray</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Keiter_P/0/1/0/all/0/1">P. A. Keiter</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lefevre_H/0/1/0/all/0/1">H. Lefevre</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Patterson_C/0/1/0/all/0/1">C. R. Patterson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Davis_J/0/1/0/all/0/1">J. S. Davis</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Powell_K/0/1/0/all/0/1">K. G. Powell</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kuranz_C/0/1/0/all/0/1">C. C. Kuranz</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Drake_R/0/1/0/all/0/1">R. P. Drake</a> Photoionization fronts play a dominant role in many astrophysical environments, but remain difficult to achieve in a laboratory experiment. Recent papers have suggested that experiments using a nitrogen medium held at ten atmospheres of pressure that is irradiated by a source with a radiation temperature of T$_{rm R}sim$ 100 eV can produce viable photoionization fronts. We present a suite of one-dimensional numerical simulations usingRead More →

Testing $Lambda$CDM With Dwarf Galaxy Morphology. (arXiv:1904.08949v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Xu_W/0/1/0/all/0/1">Weishuang Linda Xu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Randall_L/0/1/0/all/0/1">Lisa Randall</a> The leading tensions to the collisionless cold dark matter (CDM) paradigm are the “small-scale controversies”, discrepancies between observations at the dwarf-galactic scale and their simulational counterparts. In this work we consider methods to infer 3D morphological information on Local Group dwarf spheroidals, and test the fitness of CDM+hydrodynamics simulations to the observed galaxy shapes. We find that the subpopulation of dwarf galaxies with mass-to-light ratio $gtrsim 100 M_odot/L_odot$ reflects an oblate morphology. This is discrepant with the dwarf galaxies with mass-to-light ratio $lesssim 100 M_odot/L_odot$, which reflect prolate morphologies, andRead More →

The Vast Potential of Exoplanet Satellites for High-Energy Astrophysics. (arXiv:1904.08952v1 [astro-ph.IM]) <a href="http://arxiv.org/find/astro-ph/1/au:+Smith_K/0/1/0/all/0/1">Krista Lynne Smith</a> The photometric precision, monitoring baselines, and rapid, even sampling rates required by modern satellites designed for detecting the signal of transiting exoplanets are ideally suited to a large number of applications in high-energy astrophysics. I will exemplify this by discussing the results for active galactic nuclei from Kepler and summarizing other high-energy results from Kepler/K2. These precision instruments are currently underutilized for high-energy applications despite their great potential, due in part to complex systematics affecting the data. I will summarize these effects and mitigation approaches, and conclude by discussing howRead More →

Search for sub-solar mass ultracompact binaries in Advanced LIGO’s second observing run. (arXiv:1904.08976v1 [astro-ph.CO]) The <a href="http://arxiv.org/find/astro-ph/1/au:+Collaboration_LIGO_Scientific/0/1/0/all/0/1">LIGO Scientific Collaboration</a>, the <a href="http://arxiv.org/find/astro-ph/1/au:+Collaboration_Virgo/0/1/0/all/0/1">Virgo Collaboration</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+authors_a/0/1/0/all/0/1">additional authors</a> We present an Advanced LIGO and Advanced Virgo search for sub-solar mass ultracompact objects in data obtained during Advanced LIGO’s second observing run. In contrast to a previous search of Advanced LIGO data from the first observing run, this search includes the effects of component spin on the gravitational waveform. We identify no viable gravitational wave candidates consistent with sub-solar mass ultracompact binaries with at least one component between 0.2 – 1.0 solar masses. We use the null resultRead More →

Sub-GeV Dark Matter Searches and Electric Field Studies for the LUX and LZ Experiments. (arXiv:1904.08979v1 [astro-ph.IM]) <a href="http://arxiv.org/find/astro-ph/1/au:+Tvrznikova_L/0/1/0/all/0/1">Lucie Tvrznikova</a> The nature of dark matter (DM) remains a mystery since it has so far eluded detection in the laboratory. To that end, the Large Underground Xenon (LUX) experiment was built to directly observe the interaction of DM with xenon target nuclei. LUX acquired data from April 2013 to May 2016 at SURF in South Dakota, which led to publications of many world-leading exclusion limits that probe much of the unexplored DM parameter space. This manuscript describes two novel direct detection methods that used the first LUXRead More →

Observations of Solar Coronal Rain in Null Point Topologies. (arXiv:1904.08982v1 [astro-ph.SR]) <a href="http://arxiv.org/find/astro-ph/1/au:+Mason_E/0/1/0/all/0/1">E. I. Mason</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Antiochos_S/0/1/0/all/0/1">S. K. Antiochos</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Viall_N/0/1/0/all/0/1">N. M. Viall</a> Coronal rain is the well-known phenomenon in which hot plasma high in the Sun’s corona undergoes rapid cooling (from > 10^6 K to < 10^4 K), condenses, and falls to the surface. Coronal rain appears frequently in active region coronal loops and is very common in post-flare loops. This Letter presents discovery observations, which show that coronal rain is ubiquitous in the embedded bipole very near a coronal hole boundary. Our observed structures formed when the photospheric decay of active region leadingRead More →

Gravitational probes of ultra-light axions. (arXiv:1904.09003v1 [astro-ph.CO]) <a href="http://arxiv.org/find/astro-ph/1/au:+Grin_D/0/1/0/all/0/1">Daniel Grin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Amin_M/0/1/0/all/0/1">Mustafa A. Amin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gluscevic_V/0/1/0/all/0/1">Vera Gluscevic</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hlozek_R/0/1/0/all/0/1">Ren&#xe9;e Hl&#x1d2;zek</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Marsh_D/0/1/0/all/0/1">David J. E. Marsh</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Poulin_V/0/1/0/all/0/1">Vivian Poulin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Prescod_Weinstein_C/0/1/0/all/0/1">Chanda Prescod-Weinstein</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Smith_T/0/1/0/all/0/1">Tristan L. Smith</a> The axion is a hypothetical, well-motivated dark-matter particle whose existence would explain the lack of charge-parity violation in the strong interaction. In addition to this original motivation, an `axiverse’ of ultra-light axions (ULAs) with masses $10^{-33},{rm eV}lesssim m_{rm a}lesssim 10^{-10},{rm eV}$ also emerges from string theory. Depending on the mass, such a ULA contributes to the dark-matter density, or alternatively, behaves like dark energy. At these masses, ULAs’ classical wave-likeRead More →

Performance of the Gemini Planet Imager Non-Redundant Mask and spectroscopy of two close-separation binaries HR 2690 and HD 142527. (arXiv:1904.09006v1 [astro-ph.IM]) <a href="http://arxiv.org/find/astro-ph/1/au:+Greenbaum_A/0/1/0/all/0/1">Alexandra Z. Greenbaum</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cheetham_A/0/1/0/all/0/1">Anthony Cheetham</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sivaramakrishnan_A/0/1/0/all/0/1">Anand Sivaramakrishnan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rantakyro_F/0/1/0/all/0/1">Fredrik T. Rantakyr&#xf6;</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Duchene_G/0/1/0/all/0/1">Gaspard Duch&#xea;ne</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tuthill_P/0/1/0/all/0/1">Peter Tuthill</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rosa_R/0/1/0/all/0/1">Robert J. De Rosa</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Oppenheimer_R/0/1/0/all/0/1">Rebecca Oppenheimer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Macintosh_B/0/1/0/all/0/1">Bruce Macintosh</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ammons_S/0/1/0/all/0/1">S. Mark Ammons</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bailey_V/0/1/0/all/0/1">Vanessa P. Bailey</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Barman_T/0/1/0/all/0/1">Travis Barman</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bulger_J/0/1/0/all/0/1">Joanna Bulger</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cardwell_A/0/1/0/all/0/1">Andrew Cardwell</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chilcote_J/0/1/0/all/0/1">Jeffrey Chilcote</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cotten_T/0/1/0/all/0/1">Tara Cotten</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Doyon_R/0/1/0/all/0/1">Rene Doyon</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fitzgerald_M/0/1/0/all/0/1">Michael P. Fitzgerald</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Follette_K/0/1/0/all/0/1">Katherine B. Follette</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gerard_B/0/1/0/all/0/1">Benjamin L. Gerard</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Goodsell_S/0/1/0/all/0/1">Stephen J. Goodsell</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Graham_J/0/1/0/all/0/1">James R. Graham</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hibon_P/0/1/0/all/0/1">Pascale Hibon</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hung_L/0/1/0/all/0/1">Li-Wei Hung</a>, <aRead More →

New and Extended Data Processing of Mars Odyssey Neutron Spectrometer Data. (arXiv:1904.09036v1 [astro-ph.IM]) <a href="http://arxiv.org/find/astro-ph/1/au:+Mesick_K/0/1/0/all/0/1">K.E. Mesick</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Feldman_W/0/1/0/all/0/1">W.C. Feldman</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mullin_E/0/1/0/all/0/1">E.R. Mullin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Stonehill_L/0/1/0/all/0/1">L.C. Stonehill</a> The Los Alamos National Laboratory designed and built Mars Odyssey Neutron Spectrometer (MONS) has been in excellent health operating from February 2002 to the present. MONS measures the neutron leakage albedo from galactic cosmic ray bombardment of Mars. These signals can indicate the presence of near-surface water deposits on Mars, and can also be used to study properties of the seasonal polar CO2 ice caps. This work outlines a new analysis of the MONS data that results in new andRead More →

Parameter Estimation for Scarce Stellar Populations. (arXiv:1904.09054v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Ramirez_Siordia_V/0/1/0/all/0/1">V. H. Ram&#xed;rez-Siordia</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bruzual_G/0/1/0/all/0/1">G. Bruzual</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sodi_B/0/1/0/all/0/1">B. Cervantes Sodi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bitsakis_T/0/1/0/all/0/1">T. Bitsakis</a> We present a Bayesian method to determine simultaneously the age, metallicity, distance modulus, and interstellar reddening by dust of any resolved stellar population, by comparing the observed and synthetic color magnitude diagrams on a star by star basis, with no need to bin the data into a carefully selected magnitude grid. We test the method with mock stellar populations, and show that it works correctly even for scarce stellar populations with only one or two hundred stars above the main sequence turn off.Read More →

Unexpectedly strong effect of supergranulation on the detectability of Earth twins orbiting Sun-like stars with radial velocities. (arXiv:1904.09089v1 [astro-ph.EP]) <a href="http://arxiv.org/find/astro-ph/1/au:+Meunier_N/0/1/0/all/0/1">N. Meunier</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lagrange_A/0/1/0/all/0/1">A.-M. Lagrange</a> Magnetic activity and surface flows at different scales pertub radial velocity measurements. This affects the detectability of low-mass exoplanets. In these flows, the effect of supergranulation is not as well characterized as the other flows, and we wish to estimate its effect on the detection of Earth-like planets in the habitable zone of Sun-like stars. We produced time series of radial velocities due to oscillations, granulation, and supergranulation, and estimated the detection limit for a G2 star and a periodRead More →

Constraints on the small scale curvature perturbation using Planck-2015 data. (arXiv:1904.09104v1 [astro-ph.CO]) <a href="http://arxiv.org/find/astro-ph/1/au:+Yang_Y/0/1/0/all/0/1">Yupeng Yang</a> The particles emitted from PBHs through the Hawking radiation have interactions with the particles present in the Universe. Due to the interactions, the evolution of the intergalactic medium (IGM) is changed and the changes have imprints on the anisotropies of the cosmic microwave background (CMB). In this paper, we focus on the PBHs with the lifetime in the range of $10^{13}s lesssim tau_{rm PBH} lesssim 10^{17}s$, corresponding to the mass range of $2.8times 10^{13}mathrm{g} lesssim M_{mathrm{PBH}} lesssim 2.5times 10^{14}mathrm{g}$. We update the constraints on the initial mass fraction of PBHsRead More →