62 research outputs found
Tratamiento óptimo de contaminantes y sistemáticos para la explotación presente y futura de datos del Fondo Cósmico de Microondas
Uno de los hitos más esperados en cosmologÃa es la detección de las ondas gravitacionales primordiales, ya que constituirÃan una prueba irrefutable de la existencia de un periodo inflacionario. En principio, pueden medirse a través de la huella marcada en la señal del modo B del Fondo Cósmico de Microondas. Sin embargo, esta detección conlleva muchos retos desde el punto de vista experimental y de análisis de datos, ya que es relativamente débil en comparación con otras fuentes de modos B, como los contaminantes astrofÃsicos, los modos lensados de E a B, y los errores sistemáticos. Esta tesis es uno de los muchos esfuerzos en el campo del análisis de datos dedicados a la detección de esta señal de forma insesgada.
Este trabajo es una tesis por compendio de artÃculos que incluye cuatro estudios realizados en el contexto de la separación de componentes aplicada a los datos de polarización del Fondo Cósmico de Microondas. Se presenta un nuevo método de separación de componentes (B-SeCRET) que se ha aplicado en varios contextos dentro de diferentes colaboraciones e iniciativas como: simulaciones para estudios predictivos de la futura misión del satélite LiteBIRD, simulaciones de iniciativas de experimentos en tierra como ELFS, y a los datos del instrumento QUIJOTE MFI, WMAP y Planck. Además se incluyen tres aplicaciones de esta metodologÃa: 1) el estudio y optimización de los diseños experimentales, 2) la mitigación de los errores sistemáticos, y 3) la caracterización de contaminantes astrofÃsicos. En particular se probó: 1) la viabilidad de la detección de ondas gravitaciones con un telescopio terrestre operando el régimen de microondas de baja frecuencia (de 10 a 120 GHz), además de su alta complementariedad con otras misiones como LiteBIRD, 2) la posibilidad de calibrar los ángulos de polarización a partir de la señal multifrecuencia mediante dos métodos (uno basado en anular el cross espectro de potencias EB y otro parametrizando este sistemático en la parte de separación de componentes con B-SeCRET), ambas metodologÃas recuperan una estimación insesgada de la amplitud de las ondas gravitacionales primordiales, 3) la mejora en la caracterización de la emisión de sincrotrón cuando se añaden los datos del instrumento QUIJOTE-MFI junto con datos de WMAP y Planck, en particular se presenta el primer mapa detallado del Ãndice espectral del sincrotrón en hemisferio norte el cual presenta variaciones espaciales más significativas que los obtenidos con solo datos de WMAP y Planck.
En conclusión, esta tesis prueba que B-SeCRET es una metodologÃa versátil para analizar los datos presentes y futuros relativos al estudio del fondo cósmico de microondas debido a su capacidad de tratar simultáneamente con contaminantes astrofÃsicos y errores sistemáticos.One of the most awaited milestones in cosmology is the detection of primordial gravitational waves, as they would constitute compelling evidence of the existence of an inflationary period. In principle, they can be measured through their imprint in the B-mode signal of the Cosmic Microwave Background. However, this detection carries many challenges from an experimental and data analysis point of view, as it is relatively weak compared to other sources of B-modes, such as astrophysical contaminants, E-to-B lens modes, and systematic errors. This thesis is one of many efforts in the field of data analysis devoted to the detection of this signal in an unbiased manner.
This work is a compilation thesis that includes four studies performed in the context of component separation applied to Cosmic Microwave Background polarization data. A new component separation method (B-SeCRET) is presented. This method has been applied in several contexts within different collaborations and initiatives, such as simulations for predictive studies of the future LiteBIRD satellite mission, simulations of ground-based experiment initiatives such as ELFS, and QUIJOTE MFI, WMAP and Planck instrument data. In addition, three applications of this methodology are included: 1) the study and optimization of experimental designs, 2) the mitigation of systematic errors, and 3) the characterization of astrophysical contaminants. In particular, we tested: 1) the feasibility of gravitational wave detection with a ground-based telescope operating the low-frequency microwave regime (from 10 to 120 GHz), in addition to its high complementarity with other missions such as LiteBIRD, 2) the possibility of calibrating the polarization angles from the multi-frequency signal using two methods (one based on canceling the EB cross-spectrum and the other by parameterizing this systematic in the component separation part with B-SeCRET), both methodologies recover an unbiased estimate of the amplitude of the primordial gravitational waves, 3) the improvement in the characterization of the synchrotron emission when the QUIJOTE-MFI instrument data are added together with WMAP and Planck data, in particular, the first detailed map of the synchrotron spectral index in the northern hemisphere is presented, which presents more significant spatial variations than those obtained with only WMAP and Planck data.
In conclusion, this thesis proves that B-SeCRET is a versatile methodology to analyze present and future data related to the study of the cosmic microwave background due to its ability to deal simultaneously with astrophysical contaminants and systematic errors
The Fifteenth Marcel Grossmann Meeting
The three volumes of the proceedings of MG15 give a broad view of all aspects of gravitational physics and astrophysics, from mathematical issues to recent observations and experiments. The scientific program of the meeting included 40 morning plenary talks over 6 days, 5 evening popular talks and nearly 100 parallel sessions on 71 topics spread over 4 afternoons. These proceedings are a representative sample of the very many oral and poster presentations made at the meeting.Part A contains plenary and review articles and the contributions from some parallel sessions, while Parts B and C consist of those from the remaining parallel sessions. The contents range from the mathematical foundations of classical and quantum gravitational theories including recent developments in string theory, to precision tests of general relativity including progress towards the detection of gravitational waves, and from supernova cosmology to relativistic astrophysics, including topics such as gamma ray bursts, black hole physics both in our galaxy and in active galactic nuclei in other galaxies, and neutron star, pulsar and white dwarf astrophysics. Parallel sessions touch on dark matter, neutrinos, X-ray sources, astrophysical black holes, neutron stars, white dwarfs, binary systems, radiative transfer, accretion disks, quasars, gamma ray bursts, supernovas, alternative gravitational theories, perturbations of collapsed objects, analog models, black hole thermodynamics, numerical relativity, gravitational lensing, large scale structure, observational cosmology, early universe models and cosmic microwave background anisotropies, inhomogeneous cosmology, inflation, global structure, singularities, chaos, Einstein-Maxwell systems, wormholes, exact solutions of Einstein's equations, gravitational waves, gravitational wave detectors and data analysis, precision gravitational measurements, quantum gravity and loop quantum gravity, quantum cosmology, strings and branes, self-gravitating systems, gamma ray astronomy, cosmic rays and the history of general relativity
Exploring the Lensing of Cosmological Transients on Nanosecond Timescales
From gentle beach waves to violent gamma-ray bursts all transient signals are shaped by the environments through which they propagate. By understanding these propagation effects, we can use observed transients to infer properties about environments that are impossible to observe directly. Using fast radio bursts, this thesis develops our understanding of gravitational lensing and plasma scattering, as ways to constrain the identity of dark matter, and the turbulence of extragalactic material
Probing the accretion physics of Sagittarius A*
Das Galaktische Zentrum und das darin befindende massereiche Schwarze Loch Sagitarrius A* (Sgr A*) stellt einen der exotischsten Orte des Universums dar, welcher der Menschheit bekannt ist. In dieser Dissertation untersuche ich zwei verschiedene Aspekte des Galaktischen Zentrum: den Akkretionsfluss in der direkten Umgebung von Sgr A*, sowie die Verteilung der jungen Sterne, die sich in der unmittelbaren Nachbarschaft des Schwarzen Loches befinden.
Die in dieser Disseration vorgestellte Arbeit hat zu drei neuartigen Beobachtungen der spektralen Energieverteilung (englisch: Spectral Energy Distribution, SED) von Sgr A* geführt, welche ich in den ersten drei Kapitel vorstelle. Im letzten Kapitel der Thesis stelle ich meine Resultate zur Population von jungen Sterne im Galaktischen Zentrum vor.
Das erste Kapitel handelt von dem gleichzeitigen Nachweis von Sgr A* in zwei Ferninfrarotbeobachtungsbändern bei Wellenlängen von 160 μm und 100 μm. Dies sind die ersten Beobachtungen von Sgr A* in diesem Wellenlängenbereich und wurden mit der PACS Kamera on-board des Weltraumteleskops Herschel aufgezeichnet. Die Messung wurden mit Hilfe einer maßgeschneiderten Datenreduktion ermöglicht, die eine differentielle Flussmessungen im Ferninfroten mit einem bisher unerreichten Rauschpegel erlaubt. Dies führt zum ersten Nachweis des variablen Flusses mit einer Signifikanz von 4.5σ bei 160 μm und 1.6σ bei 100 μm. Die Entdeckung des variablen Flusses bestätigt, dass die SED im Sub-mm-Bereich ihr Maximum erreicht und ermöglicht die Bestimmung der Elektronendichte, der Magnetfeldstärke und der Elektronentemperatur im Akkretionsfluss. In Kombination mit modernen ALMA-Beobachtungen von Sgr A* deuten diese Ergebnisse auf niedrigere Sub-mm-Flüsse hin als bis dato angenommen wurde. Die Messergebnisse erfordern aus diesem Grund höhere Elektronentemperaturen im Akkretionsfluss. Dies deutet darauf hin, dass der Akkretionsfluss im Sub-mm- und teilweise auch im mm-Bereich optisch dünn ist.
Im zweiten Kapitel nutze ich die ersten drei Jahre der interferometrischen GRAVITY-Beobachtungen, welche am Very Large Telescope Interferometer durchgefuehrt wurden, um die Flussverteilung von Sgr A* im Nahinfraroten zu untersuchen. Aus den GRAVITY-Daten erstelle ich die erste kohärente Flussmessung von Sgr A*, die 2019 mit dem neuartigen Dual-Beam-Beobachtungsmodus beobachtet wurde. Zusätzlich, verwende ich Lichtkurven aus den Jahren 2017 und 2018, die bereits in der Literatur veröffentlicht wurden. Aufgrund der sehr hohen räumlichen Auflösung von GRAVITY wird diese Sgr A*-Flussmessung nicht durch das Licht von nahegelegenen Sternen gestört, was ähnliche auf adaptive Optik gestützte Studien in der Vergangenheit stark einschränkte. Außerdem konnte ich das Licht des Akkretionsflusses von Sgr A* zu jedem Messzeitpunkt nachweisen, eine Neuerung gegenüber den vorherrgehenden Studien, in welchen nur hellere Zustände von Sgr A* beobachtet werden konnten. Infolgedessen bin ich in der Lage, die erste rein empirische und nicht konfusionslimitierte Flussverteilung von Sgr A* zu erstellen und die 2.2 μm-Flussquantile zu messen. Durch den Vergleich mehrerer statistischer Modelle der Flussverteilung kann ich nachweisen, dass die Flussverteilung logarithmisch rechtsschief ist und nur schlecht durch eine Lognormalverteilung beschrieben wird. Im Gegensatz dazu ist die Flussverteilung gut durch ein Zweikomponentenmodell beschrieben: eine Log-Normalverteilung zur Beschreibung der Ruheemission in Kombination mit einer zweiten Komponente, die einem Potenzgesetz folgt. In diesem Szenario werden die hellen Nahinfrarot- und Röntgenflares in lokalisierten und aufgeheizten Zonen des Akkretionsstroms erzeugt, die sich von der variablen Ruheemission unterscheiden.
Das dritte Kapitel in dieser Dissertation untersucht die Eigenschaften eines solchen Flares. Ich berichte über den Nachweis eines simultanen hellen Nahinfrarot- und eines moderaten Röntgenflare. Hierbei verwende ich die Kontrollkamera von GRAVITY, um H-Band-Beobachtungen gleichzeitig zu den interferometrischen K-Band-Beobachtung zu erstellen. Desweiteren kombiniere ich diese beiden Nahinfrarot-Lichtkurven mit gleichzeitigen Beobachtungen durch die Weltraumteleskope Spitzer, Chandra und NuSTAR. Mit Hilfe der so gewonnen Flussmessung modelliere ich die Emissionsregion im Flare-Szenario. Ich berechne die SED des Flares unter Berücksichtigung der Synchrotron- und Synchrotron-Selbst-Compton-Emission. Dies erlaubt mir, die Eigenschaften der für die Emission verantwortlichen Elektronenpopulation abzuleiten. Hierbei stelle ich fest, dass die mäßige Röntgenemission entweder sehr hohe Teilchendichten erfordert oder eine Teilchenverteilung erfordert, die bei Lorentz-Faktoren, die dem Röntgenband entsprechen, abgeschnitten ist.
Für das letzte Kapitel der Disseration analysiere ich SINFONI Archivdaten der zentralen ∼ 30 ′′ × 30 ′′ Bogensekunden des Galaktischen Zentrums. Diese Analyse führt zum bis dato größten spektroskopischen Katalog dieser Region. Durch die Kombination dieser Daten konnte ich über 2800 Sterne in jung und alt klassifizieren. Über 200 junge Sterne konnten spektroskpisch identifiziert werden. Für 35 dieser junge Sterne konnte eine vollständige Lösung der Orbitgleichungen gefunden werden. Für die anderen 166 Sterne sind nur fünf von sechs Phasenraumkoordinaten bekannt. Ich stelle eine neue, und statistisch formale, Methode vor, welche die Bestimmung der Posteriorverteilung der Phasenraumkoordinaten erlaubt. Diese neue Methode erlaubt es mir, die Posteriorverteilung der Orbitelemente zu bestimmen und die Posteriorverteilung des Drehmoments der jungen Sterne zu bestimmen. Damit kann ich zeigen, dass mindestens vier verschiedene kinematische Strukturen im Galaktischen Zentrum statistisch signifkant sind. Ich bestätige die Präsenz der bekannten verdrehten Sternenscheibe, die sich im Uhrzeigersinn dreht, und der Sternenscheibe im Gegenuhrzeigersinn. Desweiteren kann ich eine neue Sternenscheibe im Galaktischen Zentrum nachweisen. Diese reichhaltige dynamische Struktur ist konsistent mit einer lokalen Bildung der jungen Sterne. Ich favorisiere die Entstehung der jungen Sternen nach Kollision zweier Molekülgaswolken.The Galactic Center, and the massive black hole Sagittarius A* (Sgr A*) therein, represent one of the most exotic places known to mankind. In this thesis, I present two aspects of the Galactic Center: the accretion flow in the direct proximity of the massive Black Hole and the distribution of young stars in its neighbourhood.
The thesis has led to three novel observations of Sgr A*’s spectral energy distribution (SED), which I present in the first three chapters of the thesis. In the last chapter of the thesis, I present my results on the young star population found in the Galactic Center.
In the first chapter, I report on the simultaneous detection of Sgr A* in two far-infrared observation bands at 160 μm and 100 μm. These are the first observations of Sgr A* in this wavelength regime obtained using the PACS camera on-board the Herschel space-telescope. The measurements are enabled by a custom-tailored data reduction pipeline, which allow far-infrared differential flux measurements in the Galactic Center at an unprecedented noise level. This led to the detection of variable flux at a significance level of 4.5σ at 160 μm and 1.6σ at 100 μm. The detection of variable flux confirms the turn-over of the SED in the sub-mm, and constrains the electron density, magnetic field strength and electron temperature. The results, in combination with modern ALMA observations of Sgr A*, imply lower than previously measured sub-mm fluxes of Sgr A* which require higher electron temperatures. This implies that the accretion flow is optically thin in the sub-mm, and parts of the mm regime.
In the second chapter, to study the flux distribution of Sgr A*. I derive the first coherent flux measurement of Sgr A* obtained from the novel dual beam observing mode in 2019. Furthermore, I use light curves of the year 2017 and 2018 which were published in literature before. Due to the very high spatial resolution of GRAVITY Sgr A*’s flux is unconfused from the light of near-by stars, which severely limited similar adaptive optics-assisted studies in the past. This allows, for the first time, to detect Sgr A* at times it is observed with GRAVITY. In consequence, I report the first purely-empirically derived and unconfused flux distribution of Sgr A* and am able to infer the 2.2 μm flux quantiles. I compare several statistical probability distributions to the observed flux distribution. I find that the flux distribution is log-right skewed and only poorly described by a log-normal distribution. The flux distribution is well described by a two-component model: a quiescent log-normal distribution in combination with a powerlaw tail. This manifests the two component consistent of a flaring and quiescence state scenario proposed for Sgr A*. In this scenario, occasional bright near-infrared and X-ray flares are generated in localized and heated zones of the accretion flow, which are distinct from the variable quiescence emission.
In the third chapter of this thesis, I study the properties of such a flare. I report the detection of a simultaneous near-infrared bright and moderate X-ray flare. I use the acquisition camera of GRAVITY to derive simultaneous H-band observations alongside the interfero-metric K-band observation. I combine the two near-infrared light curves with simultaneous observations obtained by the Spitzer, Chandra and NuSTAR spacecrafts. With the help
of these flux measurements I model the emission region in the flare-scenario and compute the flare’s SED taking into account synchrotron and synchrotron self-Compton emission. This allows me to derive the properties of electron population responsible for the emission. I find that the moderate X-ray emission either requires very high particle densities or a particle distribution which is cut at Lorentz factors corresponding to the X-ray band.
In the last chapter of the thesis I present the largest spectroscopic survey of the Galactic Center to date (∼ 30 ′′ ×30 ′′ ). Combining all available SINFONI observations of the Galactic Center allows me to classify over 2800 stars into young and old stars. My work now includes over 230 young stars, for 35 of which full orbital solutions have been determined. For the other 198 young stars only five of six phase space coordinates are known. I present a new, and statistically rigorous method to determine their posterior phase space distribution. This allows to determine the posterior distribution of orbital elements, and, specifically, to determine the ensemble angular momentum direction. Using the new statistical method I show that at least four kinematic structures in the Galactic Center are statistically significant. I confirm the presence of a warp of the clockwise disk, and the presence of a counter-clockwise disk. In addition to the previously introduced, but disputed kinematic features, I show that a third disk of young stars is present in the Galactic Center. This rich dynamical structure is consistent with an in-situ star formation scenario, and specifically, I favour a star formation event after the collision of two giant molecular clouds
Topics in microwave astronomy and cosmology
Over the past decades, precision measurements of the Cosmic Microwave Background (CMB) have led to remarkable progress in our understanding of the universe in what is known as the standard model of cosmology. In this thesis, we demonstrate the potential of high precision CMB dataset in improving our knowledge in both cosmology and astronomy.
In the first part of the thesis, we show that the upcoming CMB experiments may allow us to detect signals from the primordial magnetic field (PMF) and show that a signal from PMF may pose as a source of confusion to the signal from the primordial gravitational waves from inflation. We further show how one can effectively break the degeneracy with the help of precision measurements of the small-scale CMB anisotropies.
In the second part of the thesis, we explore the use of precision measurements of the small-scale CMB anisotropies in constraining physics beyond the standard model. With data obtained from the Atacama Cosmology Telescope (ACT), we search for a signal of parity violating physics in the early universe known as cosmic birefringence. Our non-detection allows us to place a tightest constraint on such effect at the time which improves the previous limit by a factor of 3.
In the next part of the thesis, we demonstrate that the high angular resolution CMB dataset can also be used for galactic science. By combining the CMB datasets from ACT and Planck, we make and present a map of the Galactic center region that improves the previous maps in the microwave frequencies in terms of a wider field of view, higher angular resolution, and sensitivity in both temperature and polarization measurements.
In the last part of the thesis, we discuss the prospects of the upcoming data release (DR6) from ACT which is expected to improve our constraints on cosmological parameters by a factor of 2. I provide a description of an important preprocessing step known as the data cuts pipeline, which identifies data with sporadic pathologies and removes them from the CMB mapmaking, and show the preliminary results from the pipeline for the ACT DR6
Magnetic fields in the Local Universe
This thesis comprises several research efforts centering around cosmological and astrophysical magnetic fields. In the following summary, these are shortly outlined. References and acknowledgments to the respective works are put in front of each chapter.
The first chapter entails the first prediction of today's remnants of a primordial large scale magnetic field both in strength and in three dimensional morphology within a comoving box with edge length of 600 Mpc/h. The general idea here is to translate the matter density field inferred from large scale structure data into the radiation dominated epoch up to the point where the horizon scale is much smaller than the smallest scale resolvable by the data. The density field obtained this way is used as initial conditions for the so called Harrison effect, which results in a magnetic field being generated up to recombination.
From there on, magnetic field and matter evolution are simulated via a Magnetohydrodynamics solver up to red-shift z=0, revealing the magnetic field structure today.
In chapters two to four several analyses of the Galactic Faraday depth sky are presented. Here, rotation measures of extra-Galactic point sources are used to constrain the Galactic component of the Faraday rotation sky. In a first simple inference model a full sky estimate is build from the scattered data points. A component of the inference, which is intended to model the sky amplitude, is found to have strong resemblance with the Galactic free-free emission measure sky.
Hence, building on the simple model, additional data is used to disentangle the Faraday sky into its components. In a first phenomenological model, the signature of the local Galactic arm is discovered with the help of emission measure data. In further attempts, dispersion measure data from Galactic pulsars is additionally used to give a quantitative prediction of the line-of-sight averaged Galactic magnetic field sky.
In the last chapter, two research projects revolving around circular polarization in the radio regime are summarized. In the first work, the Faraday depth sky and synchrotron intensity data are used to give a prediction on the Galactic synchrotron circular polarization sky. Due to the sensitivity of circular polarization to the charge of the synchrotron light emitting medium, statements on the leptonic content of the Milky Way can be made.
The very same property of circular polarization is used in the second paper in order to show that observations of Stokes V may help to decide whether the content of radio jets is hadronic or leptonic
Elevation and Deformation Extraction from TomoSAR
3D SAR tomography (TomoSAR) and 4D SAR differential tomography (Diff-TomoSAR) exploit multi-baseline SAR data stacks to provide an essential innovation of SAR Interferometry for many applications, sensing complex scenes with multiple scatterers mapped into the same SAR pixel cell. However, these are still influenced by DEM uncertainty, temporal decorrelation, orbital, tropospheric and ionospheric phase distortion and height blurring. In this thesis, these techniques are explored. As part of this exploration, the systematic procedures for DEM generation, DEM quality assessment, DEM quality improvement and DEM applications are first studied. Besides, this thesis focuses on the whole cycle of systematic methods for 3D & 4D TomoSAR imaging for height and deformation retrieval, from the problem formation phase, through the development of methods to testing on real SAR data. After DEM generation introduction from spaceborne bistatic InSAR (TanDEM-X) and airborne photogrammetry (Bluesky), a new DEM co-registration method with line feature validation (river network line, ridgeline, valley line, crater boundary feature and so on) is developed and demonstrated to assist the study of a wide area DEM data quality. This DEM co-registration method aligns two DEMs irrespective of the linear distortion model, which improves the quality of DEM vertical comparison accuracy significantly and is suitable and helpful for DEM quality assessment. A systematic TomoSAR algorithm and method have been established, tested, analysed and demonstrated for various applications (urban buildings, bridges, dams) to achieve better 3D & 4D tomographic SAR imaging results. These include applying Cosmo-Skymed X band single-polarisation data over the Zipingpu dam, Dujiangyan, Sichuan, China, to map topography; and using ALOS L band data in the San Francisco Bay region to map urban building and bridge. A new ionospheric correction method based on the tile method employing IGS TEC data, a split-spectrum and an ionospheric model via least squares are developed to correct ionospheric distortion to improve the accuracy of 3D & 4D tomographic SAR imaging. Meanwhile, a pixel by pixel orbit baseline estimation method is developed to address the research gaps of baseline estimation for 3D & 4D spaceborne SAR tomography imaging. Moreover, a SAR tomography imaging algorithm and a differential tomography four-dimensional SAR imaging algorithm based on compressive sensing, SAR interferometry phase (InSAR) calibration reference to DEM with DEM error correction, a new phase error calibration and compensation algorithm, based on PS, SVD, PGA, weighted least squares and minimum entropy, are developed to obtain accurate 3D & 4D tomographic SAR imaging results. The new baseline estimation method and consequent TomoSAR processing results showed that an accurate baseline estimation is essential to build up the TomoSAR model. After baseline estimation, phase calibration experiments (via FFT and Capon method) indicate that a phase calibration step is indispensable for TomoSAR imaging, which eventually influences the inversion results. A super-resolution reconstruction CS based study demonstrates X band data with the CS method does not fit for forest reconstruction but works for reconstruction of large civil engineering structures such as dams and urban buildings. Meanwhile, the L band data with FFT, Capon and the CS method are shown to work for the reconstruction of large manmade structures (such as bridges) and urban buildings
SPICA:revealing the hearts of galaxies and forming planetary systems : approach and US contributions
How did the diversity of galaxies we see in the modern Universe come to be? When and where did stars within them forge the heavy elements that give rise to the complex chemistry of life? How do planetary systems, the Universe's home for life, emerge from interstellar material? Answering these questions requires techniques that penetrate dust to reveal the detailed contents and processes in obscured regions. The ESA-JAXA Space Infrared Telescope for Cosmology and Astrophysics (SPICA) mission is designed for this, with a focus on sensitive spectroscopy in the 12 to 230 micron range. SPICA offers massive sensitivity improvements with its 2.5-meter primary mirror actively cooled to below 8 K. SPICA one of 3 candidates for the ESA's Cosmic Visions M5 mission, and JAXA has is committed to their portion of the collaboration. ESA will provide the silicon-carbide telescope, science instrument assembly, satellite integration and testing, and the spacecraft bus. JAXA will provide the passive and active cooling system (supporting the
The Apertif Surveys:The First Six Months
Apertif is a new phased-array feed for the Westerbork Synthesis Radio Telescope (WSRT), greatly increasing its field of view and turning it into a natural survey instrument. In July 2019, the Apertif legacy surveys commenced; these are a time-domain survey and a two-tiered imaging survey, with a shallow and medium-deep component. The time-domain survey searches for new (millisecond) pulsars and fast radio bursts (FRBs). The imaging surveys provide neutral hydrogen (HI), radio continuum and polarization data products. With a bandwidth of 300 MHz, Apertif can detect HI out to a redshift of 0.26. The key science goals to be accomplished by Apertif include localization of FRBs (including real-time public alerts), the role of environment and interaction on galaxy properties and gas removal, finding the smallest galaxies, connecting cold gas to AGN, understanding the faint radio population, and studying magnetic fields in galaxies. After a proprietary period, survey data products will be publicly available through the Apertif Long Term Archive (ALTA, https://alta.astron.nl). I will review the progress of the surveys and present the first results from the Apertif surveys, including highlighting the currently available public data
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