arXiv subjects

P. Hargrave

Publications and source records attributed to P. Hargrave.

At least 19 recordsLinked to original sources

arXiv2026

LiteBIRD Mission Overview after Mission Reformation

LiteBIRD is a JAXA-led space mission designed to produce all-sky microwave polarization maps. Its primary science goal is to test representative inflationary models by measuring the cosmic microwave background $B$-mode polarization generated by primordial gravitational waves, while also providing new insights into cosmology, particle physics, and astrophysics. The mission concept has been updated following the reformation activities initiated after the Mission Definition Review in 2024. The current concept preserves the central scientific objectives, while simplifying the payload configuration: a single telescope covers 12 frequency bands with band centers spanning 40 to 402~GHz, corresponding to an optical coverage of 34--448~GHz. The telescope is a cross-Dragone reflector with a 500~mm aperture diameter, cooled to approximately 5~K and coupled to transition-edge-sensor bolometer arrays operated at 0.1~K. LiteBIRD will observe from a Lissajous orbit around the Sun--Earth L2 point during a nominal 3-year survey. More specifically, the primary scientific objective is to achieve total uncertainty in the tensor-to-scalar ratio of $\delta r < 0.002$ (68\% C.L.), including contributions from foreground residuals, statistical uncertainties, instrumental systematics, and margin contingency. The corresponding map-noise requirements are specified separately for the low-, mid-, and high-frequency ranges over the reionization and recombination multipole ranges. This sensitivity makes LiteBIRD unique not only for inflationary science but also for a broad range of scientific investigations probing the history of both the early and late Universe, as well as for astrophysical processes, including Galactic science. This paper summarizes the scientific objectives, updated payload and instrument concepts, observation strategy, and ground segment plans.

astro-ph.IM↗

arXiv2024

The LiteBIRD mission to explore cosmic inflation

LiteBIRD, the next-generation cosmic microwave background (CMB) experiment, aims for a launch in Japan's fiscal year 2032, marking a major advancement in the exploration of primordial cosmology and fundamental physics. Orbiting the Sun-Earth Lagrangian point L2, this JAXA-led strategic L-class mission will conduct a comprehensive mapping of the CMB polarization across the entire sky. During its 3-year mission, LiteBIRD will employ three telescopes within 15 unique frequency bands (ranging from 34 through 448 GHz), targeting a sensitivity of 2.2\,$μ$K-arcmin and a resolution of 0.5$^\circ$ at 100\,GHz. Its primary goal is to measure the tensor-to-scalar ratio $r$ with an uncertainty $δr = 0.001$, including systematic errors and margin. If $r \geq 0.01$, LiteBIRD expects to achieve a $>5σ$ detection in the $\ell=$2-10 and $\ell=$11-200 ranges separately, providing crucial insight into the early Universe. We describe LiteBIRD's scientific objectives, the application of systems engineering to mission requirements, the anticipated scientific impact, and the operations and scanning strategies vital to minimizing systematic effects. We will also highlight LiteBIRD's synergies with concurrent CMB projects.

astro-ph.IM↗

arXiv2023

Tensor-to-scalar ratio forecasts for extended LiteBIRD frequency configurations

LiteBIRD is a planned JAXA-led CMB B-mode satellite experiment aiming for launch in the late 2020s, with a primary goal of detecting the imprint of primordial inflationary gravitational waves. Its current baseline focal-plane configuration includes 15 frequency bands between 40 and 402 GHz, fulfilling the mission requirements to detect the amplitude of gravitational waves with the total uncertainty on the tensor-to-scalar ratio, $δr$, down to $δr<0.001$. A key aspect of this performance is accurate astrophysical component separation, and the ability to remove polarized thermal dust emission is particularly important. In this paper we note that the CMB frequency spectrum falls off nearly exponentially above 300 GHz relative to the thermal dust SED, and a relatively minor high frequency extension can therefore result in even lower uncertainties and better model reconstructions. Specifically, we compare the baseline design with five extended configurations, while varying the underlying dust modeling, in each of which the HFT (High-Frequency Telescope) frequency range is shifted logarithmically towards higher frequencies, with an upper cutoff ranging between 400 and 600 GHz. In each case, we measure the tensor-to-scalar ratio $r$ uncertainty and bias using both parametric and minimum-variance component-separation algorithms. When the thermal dust sky model includes a spatially varying spectral index and temperature, we find that the statistical uncertainty on $r$ after foreground cleaning may be reduced by as much as 30--50 % by extending the upper limit of the frequency range from 400 to 600 GHz, with most of the improvement already gained at 500 GHz. We also note that a broader frequency range leads to better ability to discriminate between models through higher $χ^2$ sensitivity. (abridged)

astro-ph.CO↗

arXiv2023

Probing Cosmic Inflation with the LiteBIRD Cosmic Microwave Background Polarization Survey

LiteBIRD, the Lite (Light) satellite for the study of B-mode polarization and Inflation from cosmic background Radiation Detection, is a space mission for primordial cosmology and fundamental physics. The Japan Aerospace Exploration Agency (JAXA) selected LiteBIRD in May 2019 as a strategic large-class (L-class) mission, with an expected launch in the late 2020s using JAXA's H3 rocket. LiteBIRD is planned to orbit the Sun-Earth Lagrangian point L2, where it will map the cosmic microwave background (CMB) polarization over the entire sky for three years, with three telescopes in 15 frequency bands between 34 and 448 GHz, to achieve an unprecedented total sensitivity of 2.2$μ$K-arcmin, with a typical angular resolution of 0.5$^\circ$ at 100 GHz. The primary scientific objective of LiteBIRD is to search for the signal from cosmic inflation, either making a discovery or ruling out well-motivated inflationary models. The measurements of LiteBIRD will also provide us with insight into the quantum nature of gravity and other new physics beyond the standard models of particle physics and cosmology. We provide an overview of the LiteBIRD project, including scientific objectives, mission and system requirements, operation concept, spacecraft and payload module design, expected scientific outcomes, potential design extensions and synergies with other projects.

astro-ph.IM↗

arXiv2022

Performance of the polarization leakage correction in the PILOT data

The Polarized Instrument for Long-wavelength Observation of the Tenuous interstellar medium (PILOT) is a balloon-borne experiment that aims to measure the polarized emission of thermal dust at a wavelength of 240 um (1.2 THz). The PILOT experiment flew from Timmins, Ontario, Canada in 2015 and 2019 and from Alice Springs, Australia in April 2017. The in-flight performance of the instrument during the second flight was described in Mangilli et al. 2019. In this paper, we present data processing steps that were not presented in Mangilli et al. 2019 and that we have recently implemented to correct for several remaining instrumental effects. The additional data processing concerns corrections related to detector cross-talk and readout circuit memory effects, and leakage from total intensity to polarization. We illustrate the above effects and the performance of our corrections using data obtained during the third flight of PILOT, but the methods used to assess the impact of these effects on the final science-ready data, and our strategies for correcting them will be applied to all PILOT data. We show that the above corrections, and in particular that for the intensity to polarization leakage, which is most critical for accurate polarization measurements with PILOT, are accurate to better than 0.4 % as measured on Jupiter during flight#3.

astro-ph.IM↗

arXiv2021

Overview of the Medium and High Frequency Telescopes of the LiteBIRD satellite mission

LiteBIRD is a JAXA-led Strategic Large-Class mission designed to search for the existence of the primordial gravitational waves produced during the inflationary phase of the Universe, through the measurements of their imprint onto the polarization of the cosmic microwave background (CMB). These measurements, requiring unprecedented sensitivity, will be performed over the full sky, at large angular scales, and over 15 frequency bands from 34GHz to 448GHz. The LiteBIRD instruments consist of three telescopes, namely the Low-, Medium- and High-Frequency Telescope (respectively LFT, MFT and HFT). We present in this paper an overview of the design of the Medium-Frequency Telescope (89-224GHz) and the High-Frequency Telescope (166-448GHz), the so-called MHFT, under European responsibility, which are two cryogenic refractive telescopes cooled down to 5K. They include a continuous rotating half-wave plate as the first optical element, two high-density polyethylene (HDPE) lenses and more than three thousand transition-edge sensor (TES) detectors cooled to 100mK. We provide an overview of the concept design and the remaining specific challenges that we have to face in order to achieve the scientific goals of LiteBIRD.

astro-ph.IM↗

arXiv2021

LiteBIRD: JAXA's new strategic L-class mission for all-sky surveys of cosmic microwave background polarization

LiteBIRD, the Lite (Light) satellite for the study of B-mode polarization and Inflation from cosmic background Radiation Detection, is a space mission for primordial cosmology and fundamental physics. JAXA selected LiteBIRD in May 2019 as a strategic large-class (L-class) mission, with its expected launch in the late 2020s using JAXA's H3 rocket. LiteBIRD plans to map the cosmic microwave background (CMB) polarization over the full sky with unprecedented precision. Its main scientific objective is to carry out a definitive search for the signal from cosmic inflation, either making a discovery or ruling out well-motivated inflationary models. The measurements of LiteBIRD will also provide us with an insight into the quantum nature of gravity and other new physics beyond the standard models of particle physics and cosmology. To this end, LiteBIRD will perform full-sky surveys for three years at the Sun-Earth Lagrangian point L2 for 15 frequency bands between 34 and 448 GHz with three telescopes, to achieve a total sensitivity of 2.16 micro K-arcmin with a typical angular resolution of 0.5 deg. at 100GHz. We provide an overview of the LiteBIRD project, including scientific objectives, mission requirements, top-level system requirements, operation concept, and expected scientific outcomes.

astro-ph.IM↗

arXiv2021

Concept Design of Low Frequency Telescope for CMB B-mode Polarization satellite LiteBIRD

LiteBIRD has been selected as JAXA's strategic large mission in the 2020s, to observe the cosmic microwave background (CMB) $B$-mode polarization over the full sky at large angular scales. The challenges of LiteBIRD are the wide field-of-view (FoV) and broadband capabilities of millimeter-wave polarization measurements, which are derived from the system requirements. The possible paths of stray light increase with a wider FoV and the far sidelobe knowledge of $-56$ dB is a challenging optical requirement. A crossed-Dragone configuration was chosen for the low frequency telescope (LFT : 34--161 GHz), one of LiteBIRD's onboard telescopes. It has a wide field-of-view ($18^\circ \times 9^\circ$) with an aperture of 400 mm in diameter, corresponding to an angular resolution of about 30 arcminutes around 100 GHz. The focal ratio f/3.0 and the crossing angle of the optical axes of 90$^\circ$ are chosen after an extensive study of the stray light. The primary and secondary reflectors have rectangular shapes with serrations to reduce the diffraction pattern from the edges of the mirrors. The reflectors and structure are made of aluminum to proportionally contract from warm down to the operating temperature at $5\,$K. A 1/4 scaled model of the LFT has been developed to validate the wide field-of-view design and to demonstrate the reduced far sidelobes. A polarization modulation unit (PMU), realized with a half-wave plate (HWP) is placed in front of the aperture stop, the entrance pupil of this system. A large focal plane with approximately 1000 AlMn TES detectors and frequency multiplexing SQUID amplifiers is cooled to 100 mK. The lens and sinuous antennas have broadband capability. Performance specifications of the LFT and an outline of the proposed verification plan are presented.

astro-ph.IM↗

arXiv2021

The optical design of the LiteBIRD Middle and High Frequency Telescope

LiteBIRD is a JAXA strategic L-class mission devoted to the measurement of polarization of the Cosmic Microwave Background, searching for the signature of primordial gravitational waves in the B-modes pattern of the polarization. The onboard instrumentation includes a Middle and High Frequency Telescope (MHFT), based on a pair of cryogenically cooled refractive telescopes covering, respectively, the 89-224 GHz and the 166-448 GHz bands. Given the high target sensitivity and the careful systematics control needed to achieve the scientific goals of the mission, optical modeling and characterization are performed with the aim to capture most of the physical effects potentially affecting the real performance of the two refractors. We describe the main features of the MHFT, its design drivers and the major challenges in system optimization and characterization. We provide the current status of the development of the optical system and we describe the current plan of activities related to optical performance simulation and validation.

astro-ph.IM↗

arXiv2020

Pre-deployment Verification and Predicted Mapping Speed of MUSCAT

The Mexico-UK Submillimetre Camera for AsTronomy (MUSCAT) is a 1.1 mm receiver consisting of 1,500 lumped-element kinetic inductance detectors (LEKIDs) for the Large Millimeter Telescope (LMT; Volcán Sierra Negra in Puebla, México). MUSCAT utilises the maximum field of view of the LMT's upgraded 50-metre primary mirror and is the first México-UK collaboration to deploy a millimetre/sub-mm receiver on the Large Millimeter Telescope. Using a simplistic simulator, we estimate a predicted mapping speed for MUSCAT by combining the measured performance of MUSCAT with the observed sky conditions at the LMT. We compare this to a previously calculated bolometric-model mapping speed and find that our mapping speed is in good agreement when this is scaled by a previously reported empirical factor. Through this simulation we show that signal contamination due to sky fluctuations can be effectively removed through the use of principle component analysis. We also give an overview of the instrument design and explain how this design allows for MUSCAT to be upgraded and act as an on-sky demonstration testbed for novel technologies after the facility-class TolTEC receiver comes online.

astro-ph.IM↗

arXiv2020

MUSCAT focal plane verification

The Mexico-UK Submillimetre Camera for Astronomy (MUSCAT) is the second-generation large-format continuum camera operating in the 1.1 mm band to be installed on the 50-m diameter Large Millimeter Telescope (LMT) in Mexico. The focal plane of the instrument is made up of 1458 horn coupled lumped-element kinetic inductance detectors (LEKID) divided equally into six channels deposited on three silicon wafers. Here we present the preliminary results of the complete characterisation in the laboratory of the MUSCAT focal plane. Through the instrument's readout system, we perform frequency sweeps of the array to identify the resonance frequencies, and continuous timestream acquisitions to measure and characterise the intrinsic noise and 1/f knee of the detectors. Subsequently, with a re-imaging lens and a black body point source, the beams of every detector are mapped, obtaining a mean FWHM size of $\sim$3.27 mm, close to the expected 3.1 mm. Then, by varying the intensity of a beam filling black body source, we measure the responsivity and noise power spectral density (PSD) for each detector under an optical load of 300 K, obtaining the noise equivalent power (NEP), with which we verify that the majority of the detectors are photon noise limited. Finally, using a Fourier Transform Spectrometer (FTS), we measure the spectral response of the instrument, which indicate a bandwidth of 1.0--1.2 mm centred on 1.1 mm, as expected.

astro-ph.IM↗

arXiv2020

First Characterization of a Superconducting Filter-bank Spectrometer for Hyper-spectral Microwave Atmospheric Sounding with Transition Edge Sensors

We describe the design, fabrication, integration and characterization of a prototype superconducting filter bank with transition edge sensor readout designed to explore millimetre-wave detection at frequencies in the range 40 to 65 GHz. Results indicate highly uniform filter channel placement in frequency and high overall detection efficiency. The route to a full atmospheric sounding instrument in this frequency range is discussed.

physics.ins-det↗

arXiv2020

Updated design of the CMB polarization experiment satellite LiteBIRD

Recent developments of transition-edge sensors (TESs), based on extensive experience in ground-based experiments, have been making the sensor techniques mature enough for their application on future satellite CMB polarization experiments. LiteBIRD is in the most advanced phase among such future satellites, targeting its launch in Japanese Fiscal Year 2027 (2027FY) with JAXA's H3 rocket. It will accommodate more than 4000 TESs in focal planes of reflective low-frequency and refractive medium-and-high-frequency telescopes in order to detect a signature imprinted on the cosmic microwave background (CMB) by the primordial gravitational waves predicted in cosmic inflation. The total wide frequency coverage between 34GHz and 448GHz enables us to extract such weak spiral polarization patterns through the precise subtraction of our Galaxy's foreground emission by using spectral differences among CMB and foreground signals. Telescopes are cooled down to 5Kelvin for suppressing thermal noise and contain polarization modulators with transmissive half-wave plates at individual apertures for separating sky polarization signals from artificial polarization and for mitigating from instrumental 1/f noise. Passive cooling by using V-grooves supports active cooling with mechanical coolers as well as adiabatic demagnetization refrigerators. Sky observations from the second Sun-Earth Lagrangian point, L2, are planned for three years. An international collaboration between Japan, USA, Canada, and Europe is sharing various roles. In May 2019, the Institute of Space and Astronautical Science (ISAS), JAXA selected LiteBIRD as the strategic large mission No. 2.

astro-ph.IM↗

arXiv2019

The geometry of the magnetic field in the Central Molecular Zone measured by PILOT

We present the first far infrared (FIR) dust emission polarization map covering the full extent Milky Way's Central molecular zone (CMZ). The data, obtained with the PILOT balloon-borne experiment, covers the Galactic Center region $-2\,^\circ<l<2\,^\circ$, $-4\,^\circ<b<3\,^\circ$ at a wavelength of 240 $μ$m and an angular resolution $2.2\,'$. From our measured dust polarization angles, we infer a magnetic field orientation projected onto the plane of the sky that is remarkably ordered over the full extent of the CMZ, with an average tilt angle of $\simeq 22\,^\circ$ clockwise with respect to the Galactic plane. Our results confirm previous claims that the field traced by dust polarized emission is oriented nearly orthogonal to the field traced by GHz radio synchrotron emission in the Galactic Center region. The observed field structure is globally compatible with the latest Planck polarization data at 353 GHz and 217 GHz. Upon subtraction of the extended emission in our data, the mean field orientation that we obtain shows good agreement with the mean field orientation measured at higher angular resolution by the JCMT within the 20 km/s and 50 km/s molecular clouds. We find no evidence that the magnetic field orientation is related to the 100 pc twisted ring structure within the CMZ. We propose that the low polarization fraction in the Galactic Center region and the highly ordered projected field orientation can be reconciled if the field is strong, with a 3D geometry that is is mostly oriented $\simeq 15\,^\circ$ with respect to the line-of-sight towards the Galactic center. Assuming equipartition between the magnetic pressure and ram pressure, we obtain magnetic field strengths estimates as high as a few mG for several CMZ molecular clouds.

astro-ph.GA↗

arXiv2019

PILOT balloon-borne experiment in-flight performance

The Polarized Instrument for Long-wavelength Observation of the Tenuous interstellar medium (PILOT) is a balloon-borne experiment aiming at measuring the polarized emission of thermal dust at a wavelength of 240 mm (1.2 THz). A first PILOT flight (flight#1) of the experiment took place from Timmins, Ontario, Canada, in September 2015 and a second flight (flight#2) took place from Alice Springs, Australia in april 2017. In this paper, we present the inflight performance of the instrument during these two flights. We concentrate on performances during flight#2, but allude to flight#1 performances if significantly different. We first present a short description of the instrument and the flights. We determine the time constants of our detectors combining inflight information from the signal decay following high energy particle impacts (glitches) and of our internal calibration source. We use these time constants to deconvolve the data timelines and analyse the optical quality of the instrument as measured on planets. We then analyse the structure and polarization of the instrumental background. We measure the detector response flat field and its time variations using the signal from the residual atmosphere and of our internal calibration source. Finally, we analyze the detector noise spectral and temporal properties. The in-flight performances are found to be satisfactory and globally in line with expectations from ground calibrations. We conclude by assessing the expected in-flight sensitivity of the instrument in light of the above in-flight performances.

astro-ph.IM↗

arXiv2017

A kilo-pixel imaging system for future space based far-infrared observatories using microwave kinetic inductance detectors

Future astrophysics and cosmic microwave background space missions operating in the far-infrared to millimetre part of the spectrum will require very large arrays of ultra-sensitive detectors in combination with high multiplexing factors and efficient low-noise and low-power readout systems. We have developed a demonstrator system suitable for such applications. The system combines a 961 pixel imaging array based upon Microwave Kinetic Inductance Detectors (MKIDs) with a readout system capable of reading out all pixels simultaneously with only one readout cable pair and a single cryogenic amplifier. We evaluate, in a representative environment, the system performance in terms of sensitivity, dynamic range, optical efficiency, cosmic ray rejection, pixel-pixel crosstalk and overall yield at at an observation centre frequency of 850 GHz and 20% fractional bandwidth. The overall system has an excellent sensitivity, with an average detector sensitivity NEPdet=3x10^-19 W/rt(Hz) measured using a thermal calibration source. At a loading power per pixel of 50fW we demonstrate white, photon noise limited detector noise down to 300 mHz. The dynamic range would allow the detection of 1 Jy bright sources within the field of view without tuning the readout of the detectors. The expected dead time due to cosmic ray interactions, when operated in an L2 or a similar far-Earth orbit, is found to be <4%. Additionally, the achieved pixel yield is 83% and the crosstalk between the pixels is <-30dB. This demonstrates that MKID technology can provide multiplexing ratios on the order of a 1000 with state-of-the-art single pixel performance, and that the technology is now mature enough to be considered for future space based observatories and experiments.

astro-ph.IM↗

arXiv2014

PILOT: a balloon-borne experiment to measure the polarized FIR emission of dust grains in the interstellar medium

Future cosmology space missions will concentrate on measuring the polarization of the Cosmic Microwave Background, which potentially carries invaluable information about the earliest phases of the evolution of our universe. Such ambitious projects will ultimately be limited by the sensitivity of the instrument and by the accuracy at which polarized foreground emission from our own Galaxy can be subtracted out. We present the PILOT balloon project which will aim at characterizing one of these foreground sources, the polarization of the dust continuum emission in the diffuse interstellar medium. The PILOT experiment will also constitute a test-bed for using multiplexed bolometer arrays for polarization measurements. We present the results of ground tests obtained just before the first flight of the instrument.

astro-ph.IM↗

arXiv2012

Dust in Historical Galactic Type Ia Supernova Remnants with Herschel

The origin of interstellar dust in galaxies is poorly understood, particularly the relative contributions from supernovae and the cool stellar winds of low-intermediate mass stars. Here, we present Herschel PACS and SPIRE photometry at 70-500um of the historical young supernova remnants: Kepler and Tycho; both thought to be the remnants of Type Ia explosion events. We detect a warm dust component in Kepler's remnant with T = 82K and mass 0.0031Msun; this is spatially coincident with thermal X-ray emission optical knots and filaments, consistent with the warm dust originating in the circumstellar material swept up by the primary blast wave of the remnant. Similarly for Tycho's remnant, we detect warm dust at 90K with mass 0.0086Msun. Comparing the spatial distribution of the warm dust with X-rays from the ejecta and swept-up medium, and Ha emission arising from the post-shock edge, we show that the warm dust is swept up interstellar material. We find no evidence of a cool (25-50 K) component of dust with mass >0.07Msun as observed in core-collapse remnants of massive stars. Neither the warm or cold dust components detected here are spatially coincident with supernova ejecta material. We compare the lack of observed supernova dust with a theoretical model of dust formation in Type Ia remnants which predicts dust masses of 0.088(0.017)Msun for ejecta expanding into surrounding densities of 1(5)cm-3. The model predicts that silicon- and carbon-rich dust grains will encounter the interior edge of the observed dust emission at 400 years confirming that the majority of the warm dust originates from swept up circumstellar or interstellar grains (for Kepler and Tycho respectively). The lack of cold dust grains in the ejecta suggests that Type Ia remnants do not produce substantial quantities of iron-rich dust grains and has important consequences for the 'missing' iron mass observed in ejecta.

astro-ph.GA↗