Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p>We address in this work the instrumental systematic errors that can potentially affect the forthcoming and future Cosmic Microwave Background experiments aimed at observing its polarized emission. In particular, we focus on the systematics induced by the beam and calibration, which are considered the major sources of leakage from total intensity measurements to polarization. We simulated synthetic data sets with Time-Ordered Astrophysics Scalable Tools, a publicly available simulation and data analysis package. We also propose a mitigation technique aiming at reducing the leakage by means of a template fitting approach. This technique has shown promising results reducing the leakage by 2 orders of magnitude at the power spectrum level when applied to a realistic simulated data set of the LiteBIRD satellite mission.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Galaxy clusters are extremely over dense regions of the universe and are therefore ideal for testing how galaxy properties vary with environment. We analyze a sample of &gt;3000 galaxy spectra from 100 galaxy cluster fields, and examine trends in redshift, <jats:italic>Dn</jats:italic>4000, and a formulated in-fall proxy for member and non-member galaxies. The 4000 Å break (<jats:italic>Dn</jats:italic>4000) reveals information about the age of each galaxy, and the product of the normalized peculiar velocity and the normalized projected radius of each cluster galaxy serves as a proxy for in-fall time, or how recently each galaxy became gravitationally bound to its cluster. We see a relationship between <jats:italic>Dn</jats:italic>4000 and the in-fall proxy, with more recently in-fallen galaxies being systematically younger; we interpret this trend as the effect of environmental quenching of cluster galaxies. Furthermore, we see a trend in which all cluster galaxies become older with decreasing redshift, independent of in-fall proxy.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>V893 Sco is an ordinary dwarf nova, with a narrow eclipse that allows for exact timings of minima. These eclipse times have been used to seek variations (compared to a linear ephemeris) by placement onto a traditional <jats:italic>O</jats:italic> − <jats:italic>C</jats:italic> diagram. Bruch collected 114 eclipse times from 1999 to 2013, and noted that the residuals in his <jats:italic>O</jats:italic> − <jats:italic>C</jats:italic> diagram had an apparent sinusoidal variation with a period of 10.2 yr. After rejecting a variety of possibilities, Bruch settled on the explanation that the binary was orbited by a planet with the mass of 9.5 Jupiters. We have tested this planet proposal by extending the <jats:italic>O</jats:italic> − <jats:italic>C</jats:italic> curve to 2014 and 2020–2021. For this, we measured 987 eclipse times in 2014 with the K2 mission, plus we measured 305 eclipse times in 2020 and 2021 with a remotely controlled observatory in the Atacama. We find that the <jats:italic>O</jats:italic> − <jats:italic>C</jats:italic> curve suffers a sharp break (from Bruch’s sinewave) to a shorter period after 2013. Thus, the planet-hypothesis has failed.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The altitude distribution of ground-based reflecting telescopes with primary mirrors of diameter 1.0 m or more is presented graphically and compared with hypsographic data for the Earth’s land surface. It is verified that large optical reflectors are more weighted to higher elevations than the land surface. Approximately 60% of the combined collecting area of the telescopes is situated between elevations of 2000 and 3500 m.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present a video of a simulation showing the expansion front of a technological species settling a Milky Way-like galaxy, created using the model described in Carroll-Nellenback et al. It illustrates how even very conservative rates of settlement ship launches and ship ranges can quickly lead to a galaxy endemic with technology, and how the rotational and peculiar motions of stars contributes to the expansion. This video confirms and validates previous work showing that the centers of galaxies are promising search directions for SETI.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>In the course of surveying spiral galaxies in the Local Volume, long exposures of NGC 3416 show two probable stellar streams with the possible remnant of a satellite galaxy. I captured the discovery image using the Schulman Telescope at Steward Observatory's Mount Lemmon Sky Center (University of Arizona). I acquired the wide bandpass data over three nights under photometric conditions in 2015 February. Prominent theories of galaxy formation hold that the creation of present-day galaxies are the aggregation of many past minor mergers. Stellar streams lend credence to the idea by presenting evidence of extended low surface brightness tidally created signatures. NGC 3614 appears to be a good example the for kind of extended features expected by these theories.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) will discover ∼6 million solar system planetesimals, providing in total over a billion photometric and astrometric measurements in 6 broad-band filters. Rubin Observatory's automated data reduction pipelines will employ difference imaging; templates representing the static sky will be subtracted from the nightly LSST observations in order to identify transient sources, including solar system moving objects. These templates are expected to be generated by coadding high quality images of the same pointing from the previous year's survey observations. The first year of LSST operations will require a different method for generating templates, if solar system discoveries are to be reported daily like Year 2 and beyond. We make recommendations for template production in the LSST's first year and present the opportunities for solar system small body transient and time domain science enhanced by this change.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We estimate the evolution of the galaxy–galaxy merger fraction for <jats:italic>M</jats:italic> <jats:sub>⋆</jats:sub> &gt; 10<jats:sup>10.5</jats:sup> <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> galaxies over 0.25 &lt; <jats:italic>z</jats:italic> &lt; 1 in the ∼18.6 deg<jats:sup>2</jats:sup> deep CLAUDS+HSC-SSP surveys. We do this by training a Random Forest Classifier to identify merger candidates from a host of parametric morphological features, and then visually follow-up likely merger candidates to reach a high-purity, high-completeness merger sample. Correcting for redshift-dependent detection bias, we find that the merger fraction at <jats:italic>z</jats:italic> = 0 is 1.0% ± 0.2%, that the merger fraction evolves as (1 + <jats:italic>z</jats:italic>)<jats:sup>2.3 ± 0.4</jats:sup>, and that a typical massive galaxy has undergone ∼0.3 major mergers since <jats:italic>z</jats:italic> = 1. This pilot study illustrates the power of very deep ground-based imaging surveys combined with machine learning to detect and study mergers through the presence of faint, low surface brightness merger features out to at least <jats:italic>z</jats:italic> ∼ 1.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Early migration damped Neptune's eccentricity. Here, we assume that the damped value was much smaller than the value observed today, and show that the closest flyby of ∼0.1 <jats:italic>M</jats:italic> <jats:sub>⊙</jats:sub> star over ∼4.5 Gyr in the field, at a distance of ∼10<jats:sup>3</jats:sup> au would explain the value of Neptune's eccentricity observed today.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We have conducted an Arecibo 327 MHz search of two dwarf irregular galaxies in the Local Group, Leo A and T, for radio pulsars and single pulses from fast radio bursts and other giant pulse emitters. We detected no astrophysical signals in this search, and we estimate flux density limits on both periodic and burst emission. Our derived luminosity limits indicate that only the most luminous radio pulsars known in our Galaxy and in the Magellanic Clouds (MCs) would have been detectable in our search if they were at the distances of Leo A and T. Given the much smaller stellar mass content and star formation rates of Leo A and T compared to the Milky Way and the MCs, there are likely to be few (if any) extremely luminous pulsars in these galaxies. It is therefore not surprising that we detected no pulsars in our search.</jats:p>