Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title> <jats:p> <jats:sc>deep</jats:sc>CR is a deep-learning-based cosmic-ray rejection algorithm previously demonstrated to be superior to state-of-the-art <jats:sc>LACosmic</jats:sc> on Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS)/WFC F606W imaging data. In this research note, we present a new <jats:sc>deep</jats:sc>CR model for use on all filters of HST ACS/WFC. We train and test the model with ACS/WFC F435W, F606W, and F814W images, covering the entire spectral range of the ACS optical channel. The global model demonstrates near 100% detection rates of CRs in extragalactic fields and globular clusters and 91% in resolved galaxy fields. We further confirm the global applicability of the model by comparing its performance against single-filter models that were trained simultaneously and by testing the global model on data from another filter which was not previously used for training.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Using data from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) Survey, we examined a subsample of 29 E+A galaxy candidates in the Coma Cluster. We created spatially-resolved maps of spectral features and the kinematics of the underlying stellar population by utilizing the Marvin toolkit. We rule out star formation in the entire subsample, and do not find evidence for AGN activity. For the majority of the subsample, stellar rotation is coherent.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The Simons Observatory is a Cosmic Microwave Background experiment to observe the microwave sky in six frequency bands from 30 to 290 GHz. The Observatory—at ∼5200 m altitude—comprises three Small Aperture Telescopes and one Large Aperture Telescope (LAT) at the Atacama Desert, Chile. This research note describes the design and current status of the LAT along with its future timeline.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Radio-loud quasars (RLQs) are known to produce excess X-ray emission, compared to radio-quiet quasars (RQQs) of the same luminosity, commonly attributed to jet-related emission. Recently, we found that the  He <jats:sc>ii</jats:sc> EW and <jats:italic>α</jats:italic> <jats:sub>ox</jats:sub> in RQQs are strongly correlated, which suggests that their extreme-ultraviolet (EUV) and X-ray emission mechanisms are tightly related. Using 48 RLQs, we show that steep-spectrum radio quasars (SSRQs) and low radio-luminosity (<jats:inline-formula> <jats:tex-math> <?CDATA ${L}_{{\rm{R}}}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>L</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">R</mml:mi> </mml:mrow> </mml:msub> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="rnaasabfbe5ieqn1.gif" xlink:type="simple" /> </jats:inline-formula>) flat-spectrum radio quasars (FSRQs) follow the <jats:inline-formula> <jats:tex-math> <?CDATA ${\alpha }_{\mathrm{ox}}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>α</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>ox</mml:mi> </mml:mrow> </mml:msub> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="rnaasabfbe5ieqn2.gif" xlink:type="simple" /> </jats:inline-formula>– He <jats:sc>ii</jats:sc> EW relation of RQQs. This suggests that the X-ray and EUV emission mechanisms in these types of RLQs is the same as in RQQs, and is not jet related. High-<jats:inline-formula> <jats:tex-math> <?CDATA ${L}_{{\rm{R}}}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>L</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">R</mml:mi> </mml:mrow> </mml:msub> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="rnaasabfbe5ieqn3.gif" xlink:type="simple" /> </jats:inline-formula> FSRQs show excess X-ray emission given their  He <jats:sc>ii</jats:sc> EW by a factor of ≈3.5, which suggests that only in this type of RLQ is the X-ray production likely jet related.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present a simple but informative online tool to visualize the multiwavelength (MW) properties of ≈2700 X-ray sources from Chandra Source Catalog version 2.0 with literature verified classifications. Here we describe the catalogs that we used to collect the classifications and extract the MW properties of these sources, and the properties themselves. We also describe the design and functionality of the tool.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Cumulative hardness comparisons are a simple but statistically powerful test for the presence of gravitational lensing in gamma-ray bursts (GRBs). Since gravitational lensing does not change photon energies, all source images should have the same spectra—and hence hardness. Applied to the recent claim that the two pulses in GRB 950830 are lensed images of the same pulse, the measured flux ratio between the two main pulses should be the same at all energies. After summing up all the counts in both of GRB 950830's two pulses in all four BATSE energy bands, it was found that in energy channel 3, the second pulse appears somewhat weak. In comparison with the other BATSE energy channels, the difference was statistically significant at above 90%. This model-independent test indicates that the case for GRB 950830 involving a gravitational lens may be intriguing—but should not be considered proven.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Abundances for 20 chemical elements are derived for Maia, the fourth brightest member of the Pleiades, using updated atomic data. Maia does not seem to be a typical helium-weak star nor a classical HgMn star. Instead Maia might be related to the phosphorus and gallium-rich stars.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The intrinsic nature of many astronomical objects, such as binary systems, exoplanets, circumstellar disks, and quasar host galaxies, introduces challenging requirements on observational instrumentation and techniques. In each case, we encounter situations where the light from bright sources completely outshines the surrounding faint targets. As a result, we are yet to fully understand the processes governing star and galaxy formation and evolution, and there are ongoing attempts to search for habitable worlds around other stars. To explore all features of such astronomical objects, we must perform observations at the maximum possible contrast ratios. Here, we demonstrate the extreme contrast ratio imaging capabilities of the latest generation of commercially available charge injection devices, the SpectraCAM XDR, using Sirius field observations from a world-class observing site. Based on wavelet-based image analysis and precise photometric calibration, we report a direct contrast ratio of 1 part in 100 million.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We revisit Wagoner et al., a classic contribution in the development of Big Bang Nucleosynthesis. We demonstrate that it presents an incorrect expression for the temperature of the early universe as a function of time in the high temperature limit, <jats:inline-formula> <jats:tex-math> <?CDATA $T\gtrsim {10}^{10}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>T</mml:mi> <mml:mo>≳</mml:mo> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> </mml:msup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="rnaasabf9acieqn1.gif" xlink:type="simple" /> </jats:inline-formula> K. As this incorrect expression has been reproduced elsewhere, we present a corrected form for the initial conditions required for calculating the formation of the primordial elements in the Big Bang.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Gaussian processes (GPs) are used widely in the analysis of astronomical time series. GPs with rational spectral densities have state-space representations which allow <jats:inline-formula> <jats:tex-math> <?CDATA ${ \mathcal O }(n)$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi mathvariant="italic"></mml:mi> <mml:mo stretchy="true">(</mml:mo> <mml:mi>n</mml:mi> <mml:mo stretchy="true">)</mml:mo> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="rnaasabfe68ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> evaluation of the likelihood. We calculate analytic state space representations for the damped simple harmonic oscillator and the Matérn 1/2, 3/2 and 5/2 processes.</jats:p>