Cristian Vargas
A5102837175- Galaxies: Formation, Evolution, Phenomena
- Radio Astronomy Observations and Technology
- Astronomy and Astrophysical Research
- Astrophysics and Cosmic Phenomena
- Cosmology and Gravitation Theories
- Stellar, planetary, and galactic studies
- Gamma-ray bursts and supernovae
- Astrophysics and Star Formation Studies
- Dark Matter and Cosmic Phenomena
- History and Developments in Astronomy
- Neutrino Physics Research
- Astrophysical Phenomena and Observations
- Climate variability and models
- Pulsars and Gravitational Waves Research
- Astronomical Observations and Instrumentation
- Solar and Space Plasma Dynamics
- Astro and Planetary Science
- Scientific Research and Discoveries
- Particle physics theoretical and experimental studies
- Atmospheric Ozone and Climate
- Complex Systems and Time Series Analysis
- Adaptive optics and wavefront sensing
- Superconducting and THz Device Technology
- Image and Signal Denoising Methods
Pontificia Universidad Católica de Chile
2022-2024
University of Michigan
2023
Columbia University
2023
Florida State University
2022
Universidad Nacional Autónoma de México
2020
Abstract We present tomographic measurements of structure growth using cross-correlations Atacama Cosmology Telescope (ACT) DR6 and Planck cosmic microwave background (CMB) lensing maps with the unWISE Blue Green galaxy samples, which span redshift ranges 0.2 ≲ z 1.1 0.3 1.8, respectively. improve on prior not just by making use new, high-precision ACT maps, but also including additional spectroscopic data for calibration analyzing our a more flexible theoretical model. determine amplitude...
We use data from the Atacama Cosmology Telescope (ACT) DR4 to search for presence of neutrino self-interaction in cosmic microwave background. Consistent with prior works, posterior distributions we find are bimodal, one mode consistent $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$ and where neutrinos strongly self-interact. By combining ACT large-scale information WMAP, that a delayed onset free streaming caused by significantly strong is compatible these at...
ABSTRACT We derive limits on any electromagnetic counterpart to the compact binary merger S190814bv, whose parameters are consistent with of a black hole and neutron star. present observations new wide-field optical imager DDOTI also consider Swift/BAT reported by Palmer et al. show that would have detected similar properties typical on-axis short GRB at 98 per cent confidence level, whereas our only rule out such 27 level. Neither has sufficient sensitivity an off-axis like GW 170817....
Recent advances in cosmological observations have provided an unprecedented opportunity to investigate the distribution of baryons relative underlying matter. In this work, we robustly show that gas is much more extended than dark matter at 40$\sigma$ and amount baryonic feedback $z \lesssim 1$ strongly disfavors low-feedback models such as state-of-the-art hydrodynamical simulation IllustrisTNG compared with high-feedback original Illustris simulation. This has important implications for...
The kinematic and thermal Sunyaev-Zel'dovich (kSZ tSZ) effects probe the abundance thermodynamics of ionized gas in galaxies clusters. We present a new hybrid estimator to measure kSZ effect by combining cosmic microwave background temperature anisotropy maps with photometric spectroscopic optical survey data. method interpolates velocity reconstruction from catalog at positions objects catalog, which makes it possible leverage high number density precision survey. Combining this measurement...
Abstract The increasing statistical power of cosmic microwave background (CMB) datasets requires a commensurate effort in understanding their noise properties. maps from ground-based instruments is dominated by large-scale correlations, which poses modeling challenge. This paper develops novel models the complex covariance structure Atacama Cosmology Telescope Data Release 6 (ACT DR6) maps. We first enumerate properties that arise combination atmosphere and ACT scan strategy. then prescribe...
Spatial variations in the cosmic electron density after reionization generate microwave background anisotropies via Thomson scattering, a process known as ``patchy screening" effect. In this paper, we propose new estimator for patchy screening effect that is designed to mitigate biases from dominant foreground signals. We use it measure cross-correlation between \textit{unWISE} galaxies and screening, latter measured by Atacama Cosmology Telescope \textit{Planck} satellite. report first...
Abstract Diverse astrophysical observations suggest the existence of cold dark matter that interacts only gravitationally with radiation and ordinary baryonic matter. Any nonzero coupling between baryons would provide a significant step towards understanding particle nature Measurements cosmic microwave background (CMB) constraints on such complement laboratory searches. In this work we place upper limits variety models for elastic scattering protons electrons by combining large-scale CMB...
Abstract We present fluxes and light curves for a population of asteroids at millimeter wavelengths, detected by the Atacama Cosmology Telescope (ACT) over 18,000 deg 2 sky using data from 2017 to 2021. utilize high cadence maps, which can be used in searching moving objects such as trans-Neptunian Objects, well studying transients. detect 170 with signal-to-noise least 5 one ACT observing bands, are centered near 90, 150, 220 GHz. For each asteroid, we compare measured flux predicted...
Abstract We conduct a systematic search for transients in 3 yr of data (2017–2019) from the Atacama Cosmology Telescope (ACT). ACT covers 40% sky at three bands spanning 77–277 GHz. Analysis day mean-subtracted maps, which were match filtered point sources, yielded 29 transient detections. Eight these are due to known asteroids, and others previously published. Four events occur areas with poor noise models thus we cannot be confident they real transients. left 14 new occurring 11 unique...
We use data from the Atacama Cosmology Telescope (ACT) DR4 to search for presence of neutrino self-interaction in cosmic microwave background. Consistent with prior works, posterior distributions we find are bimodal, one mode consistent $\Lambda$CDM and where neutrinos strongly self-interact. By combining ACT large-scale information WMAP, that a delayed onset free streaming caused by significantly strong is compatible these at $2-3\sigma$ level. As seen past, preference shifts inclusion...
Abstract We present a cross-correlation analysis between <?CDATA $1^{\prime} $?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>1</mml:mn> <mml:mo accent="false">′</mml:mo> </mml:math> resolution total intensity and polarization observations from the Atacama Cosmology Telescope (ACT) at 150 220 GHz 15″ mid-infrared photometry Wide-field Infrared Survey Explorer (WISE) over 107 12.°5 × patches of sky. detect spatially isotropic signal in WISE×ACT TT...
ABSTRACT We measure the local correlation between radio emission and Compton-y signal across two galaxy clusters, Abell 399 401, using maps from Low Frequency Array Atacama Cosmology Telescope + Planck. These data sets allow us to make first measurement of this kind at ∼arcmin resolution. find that brightness scales as Fradio ∝ y1.5 for 401 y2.8 399. Furthermore, XMM–Newton data, we derive a sublinear X-ray both clusters ($F_{\mathrm{radio}} \propto F_{\rm X}^{0.7}$). Finally, correlate...
We present fluxes and light curves for a population of asteroids at millimeter (mm) wavelengths, detected by the Atacama Cosmology Telescope (ACT) over 18, 000 deg2 sky using data from 2017 to 2021. utilize high cadence maps, which can be used in searching moving objects such as trans-Neptunian Objects (TNOs), well studying transients. detect 160 with signal-to-noise least 5 one ACT observing bands, are centered near 90, 150, 220 GHz. For each asteroid, we compare measured flux predicted...
We present tomographic measurements of structure growth using cross-correlations Atacama Cosmology Telescope (ACT) DR6 and Planck CMB lensing maps with the unWISE Blue Green galaxy samples, which span redshift ranges $0.2 \lesssim z 1.1$ $0.3 1.8$, respectively. improve on prior not just by making use new, high-precision ACT maps, but also including additional spectroscopic data for calibration analysing our a more flexible theoretical model. An extensive suite systematic null tests within...
We have performed targeted searches of known, extragalactic transient events at millimetre wavelengths using nine seasons (2013--2021) 98, 150, and 229 GHz Atacama Cosmology Telescope (ACT) observations that mapped ${\sim}40$ per cent the sky for most data volume. observe least once 88 gamma-ray bursts (GRBs), 12 tidal disruption (TDEs) 203 other transients, including supernovae (SNe). stack our ACT to increase signal-to-noise ratio maps. In all cases but one, we do not detect these...
We present weak gravitational lensing measurements of a sample 157 clusters within the Kilo Degree Survey (KiDS), detected with $>5σ$ thermal Sunyaev-Zel'dovich (SZ) signal by Atacama Cosmology Telescope (ACT). Using halo-model approach we constrain average total cluster mass, $M_{\rm WL}$, accounting for ACT selection function full sample. find that SZ mass estimate SZ}$, which was calibrated using X-ray observations, is biased SZ}/M_{\rm WL} = (1-b_{\rm SZ}) 0.65\pm 0.05$. Separating...
ABSTRACT We have performed targeted searches of known extragalactic transient events at millimetre wavelengths using nine seasons (2013–2021) 98, 150, and 229 GHz Atacama Cosmology Telescope (ACT) observations that mapped ∼40 per cent the sky for most data volume. Our cover 88 gamma-ray bursts (GRBs), 12 tidal disruption (TDEs), 203 other transients, including supernovae (SNe). stack our ACT to increase signal-to-noise ratio maps. In all cases but one, we do not detect these transients in...
In the current paradigm, high redshift radio halos are expected to be scarce due inverse Compton energy losses and dimming, which cause them intrinsically faint. This low occurrence fraction is predicted by cosmic ray electron turbulent re-acceleration models. To date, only a handful of have been detected at z > 0.8. We report MeerKAT detection halo hosted galaxy cluster ACT-CL J0329.2-2330 = 1.23, making it highest thus far. Using L-band UHF-band observations, we derive spectral index...
Abstract ACT-CL J0034.4+0225 is a previously unrecognized merging galaxy cluster at z = 0.38588 ± 0.00068. Our primary evidence provided by 21 ks Chandra image that shows two surface brightness peaks separated ∼49″ (259 kpc) surrounded an extended gas distribution. Each peak contains brightest galaxy, offset from the peak. We collect new South African Large Telescope optical spectra that, when augmented archival data, yield redshifts for BGCs and 58 other members. Archival Giant Metrewave...
We conduct a systematic search for astrophysical transients using data from the Atacama Cosmology Telescope (ACT). The were taken 2017 to 2022 in three frequency bands spanning 77 GHz 277 GHz. In this paper we present pipeline transient detection single observation maps where each pixel of map contains one with an integration time approximately four minutes. find 34 events at 27 unique locations. All but two are associated Galactic stars and exhibit wide range properties. also detect event...
The increasing statistical power of cosmic microwave background (CMB) datasets requires a commensurate effort in understanding their noise properties. maps from ground-based instruments is dominated by large-scale correlations, which poses modeling challenge. This paper develops novel models the complex covariance structure Atacama Cosmology Telescope Data Release 6 (ACT DR6) maps. We first enumerate properties that arise combination atmosphere and ACT scan strategy. then prescribe class...
We conduct a systematic search for transients in three years of data (2017-2019) from the Atacama Cosmology Telescope (ACT). ACT covers 40 percent sky at bands spanning 77 GHz to 277 GHz. Analysis 3-day mean-subtracted maps, which were match-filtered point sources, yielded 29 detections. Eight these are due known asteroids, and others previously published. Four events occur areas with poor noise models thus we cannot be confident they real transients. left 14 new transient occurring 11...