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Modern astrophysics relies on intricate instrument setups to meet the demands of sensitivity, sky coverage, and multi-channel observations. An example is the CONCERTO project, employing advanced technology like kinetic inductance detectors and a Martin-Puplett interferometer. This instrument, installed at the APEX telescope atop the Chajnantor plateau, began commissioning observations in April 2021. Following a successful commissioning phase that concluded in June 2021, CONCERTO was offered to the scientific community for observations, with a final observing run in December 2022. CONCERTO boasts an 18.5 arcmin field of view and a spectral resolution down to 1.45 GHz in the 130-310 GHz electromagnetic band. We developed a comprehensive instrument model of CONCERTO inspired by Fourier transform spectrometry principles to optimize performance and address systematic errors. This model integrates instrument noises, subsystem characteristics, and celestial signals, leveraging both physical data and simulations. Our methodology involves delineating simulation components, executing on-sky simulations, and comparing results with real observations. The resulting instrument model is pivotal, enabling a precise error correction and enhancing the reliability of astrophysical insights obtained from observational data. In this work, we focus on the description of three white-noise noise components included in the instrument model that characterize the white-noise level: the photon, the generation-recombination, and the amplifier noises., Comment: 8 pages, 1 figure, Proceeding of the SPIE conference Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy XII, SPIE Astronomical Telescopes + Instrumentation 2024

CarbON CII line in post-rEionization and ReionizaTiOn (CONCERTO) is a low-resolution spectrometer with an instantaneous field-of-view of 18.6 arcmin, operating in the 130-310 GHz transparent atmospheric window. It is installed on the 12-meter Atacama Pathfinder Experiment (APEX) telescope at 5100 m above sea level. The Fourier transform spectrometer (FTS) contains two focal planes hosting a total of 4304 kinetic inductance detectors. The FTS interferometric pattern is recorded on the fly while continuously scanning the sky. One of the goals of CONCERTO is to characterize the large-scale structure of the Universe by observing the integrated emission from unresolved galaxies. This methodology is an innovative technique and is called line intensity mapping. In this paper, we describe the CONCERTO instrument, the effect of the vibration of the FTS beamsplitter, and the status of the CONCERTO main survey., Comment: 9 pages, 7 figures, to appear in the Proceedings of SPIE Astronomical Telescopes + Instrumentation 2022

We describe the on-line algorithms developed to probe Lumped Element Kinetic Inductance Detectors (LEKID) in this paper. LEKIDs are millimeter wavelength detectors for astronomy. LEKID arrays are currently operated in different instruments as: NIKA2 at the IRAM telescope in Spain, KISS at the Teide Observatory telescope in Tenerife, and CONCERTO at the APEX 12-meter telescope in Chile. LEKIDs are superconducting microwave resonators able to detect the incoming light at millimeter wavelengths and they are well adapted for frequency multiplexing (currently up to 360 pixels on a single microwave guide). Nevertheless, their use for astronomical observations requires specific readout and acquisition systems both to deal with the instrumental and multiplexing complexity, and to adapt to the observational requirements (e.g. fast sampling rate, background variations, on-line calibration, photometric accuracy, etc). This paper presents the different steps of treatment from identifying the resonance frequency of each LEKID to the continuous automatic control of drifting LEKID resonance frequencies induced by background variations.

We have developed a new software to perform the measurement of galaxy cluster pressure profiles from high angular resolution thermal SZ observations. The code allows the user to take into account various features of millimeter observations, such as point spread function (PSF) convolution, pipeline filtering, correlated residual noise, and point source contamination, in a forward modeling approach. One of the key advantages of the code is the possibility to use binned, non-parametric pressure profiles, enabling the detection of pressure features better than smooth functions such as the traditionally used generalized Navarro-Frenk-White profile. Another major upside is the performance of the software, enabling the extraction of the pressure profile and associated confidence intervals via MCMC sampling in times as short as a few minutes. We present the code and its validation on various realistic synthetic maps, of ideal spherical clusters, as well as of realistic, hydrodynamically simulated objects. We plan to publicly release the software in the coming months., Comment: To appear in the Proceedings of the International Conference entitled "mm Universe @ NIKA2", Rome (Italy), June 2021, EPJ Web of conferences

One of the key elements needed to perform the cosmological exploitation of a cluster survey is the relation between the survey observable and the cluster masses. Among these observables, the integrated Compton parameter $Y$ is a measurable quantity in Sunyaev-Zeldovich (SZ) surveys, which tightly correlates with cluster mass. The calibration of the relation between the Compton parameter $Y_{500}$ and the mass $M_{500}$ enclosed within radius $R_{500}$ is one of the scientific goals of the NIKA2 SZ Large Program (LPSZ). We present an ongoing study to forecast the constraining power of this program, using mock simulated datasets that mimic the large program sample, selection function, and typical uncertainties on $Y_{500}$ and $M_{500}$. We use a Bayesian hierarchical modeling that enables taking into account a large panel of systematic effects. Our results show that the LPSZ can yield unbiased estimates of the scaling relation parameters for realistic input parameter values. The relative uncertainties on these parameters is $\sim 10\%$ for the intercept and slope of the scaling relation, and $\sim 34\%$ for its intrinsic scatter, foreshadowing precise estimates to be delivered by the LPSZ., Comment: To appear in the Proceedings of the International Conference entitled "mm Universe @ NIKA2", Rome (Italy), June 2021, EPJ Web of conferences

The polarized Galactic synchrotron and thermal dust emission constitutes a major tool in the study of the Galactic magnetic field (GMF) and in constraining its strength and geometry for the regular and turbulent components. In this paper, we review the modeling of these two components of the polarized Galactic emission and present our strategy for optimally exploiting the currently existing data sets. We investigate a Markov Chain Monte Carlo (MCMC) method to constrain the model parameter space through maximum-likelihood analysis, focusing mainly on dust polarized emission. Relying on simulations, we demonstrate that our methodology can be used to constrain the regular GMF geometry. Fitting for the reduced Stokes parameters, this reconstruction is only marginally dependent of the accuracy of the reconstruction of the Galactic dust grain density distribution. However, the reconstruction degrades, apart from the pitch angle, when including a turbulent component on the order of the regular one as suggested by current observational constraints. Finally, we applied this methodology to a set of $Planck$ polarization maps at 353 GHz to obtain the first MCMC based constrains on the large-scale regular-component of the GMF from the polarized diffuse Galactic thermal dust emission. By testing various models of the dust density distribution and of the GMF geometry, we prove that it is possible to infer the large-scale geometrical properties of the GMF. We obtain coherent three-dimensional (3D) views of the GMF, from which we infer a mean pitch angle of 27 degrees with 14 % scatter, which is in agreement with results obtained in the literature from synchrotron emission., Comment: Matches the version accepted by A&A

A tremendous international effort is currently dedicated to observing the so-called $B$-modes of the Cosmic Microwave Background (CMB) polarisation. At the unprecedented sensitivity level that the new generation of CMB experiments aims to reach, every uncontrolled instrumental systematic effect will potentially result in an analysis bias that is larger than the much sought-after CMB $B$-mode signal. The absolute calibration of the polarisation angle is particularly important in this sense, as any associated error will end up in a leakage from the much larger $E$ modes into $B$ modes. The Crab nebula (Tau A), with its bright microwave synchrotron emission, is one of the few objects in the sky that can be used as absolute polarisation calibrators. In this paper we review the best current constraints on its polarisation angle from 23 to 353 GHz, at typical angular scales for CMB observations, from WMAP, XPOL, Planck and NIKA data. These polarisation angle measurements are compatible with a constant angle of $-88.19\,^\circ\pm0.33\,^\circ$. We study the uncertainty on this mean angle, making different considerations on how to combine the individual measurement errors. For each of the cases, we study the potential impact on the CMB $B$-mode spectrum and on the recovered $r$ parameter, through a likelihood analysis. We find that current constraints on the Crab polarisation angle, assuming it is constant through microwave frequencies, allow to calibrate experiments with an accuracy enabling the measurement of $r\sim0.01$. On the other hand, even under the most optimistic assumptions, current constraints will lead to an important limitation for the detection of $r\sim10^{-3}$. New realistic measurement of the Crab nebula can change this situation, by strengthening the assumption of the consistency across microwave frequencies and reducing the combined error., Comment: 7 pages, 4 figures, submitted to A&A

We constrain the dark energy equation of state parameter, $w$, using the power spectrum of the thermal Sunyaev-Zeldovich (tSZ) effect. We improve upon previous analyses by taking into account the trispectrum in the covariance matrix and marginalising over the foreground parameters, the correlated noise, the mass bias $B$ in the Planck universal pressure profile, and all the relevant cosmological parameters (i.e., not just $\Omega_{\mathrm{m}}$ and $\sigma_8$). We find that the amplitude of the tSZ power spectrum at $\ell\lesssim 10^3$ depends primarily on $F\equiv \sigma_{8}(\Omega_{{\mathrm{m}}}/B)^{0.40}h^{-0.21}$, where $B$ is related to more commonly used variable $b$ by $B=(1-b)^{-1}$. We measure this parameter with 2.6\% precision, $F=0.460\pm 0.012$ (68% CL). By fixing the bias to $B=1.25$ and adding the local determination of the Hubble constant $H_0$ and the amplitude of the primordial power spectrum constrained by the Planck Cosmic Microwave Background (CMB) data, we find $w=-1.10\pm0.12$, $\sigma_{\mathrm{8}}=0.802\pm0.037$, and $\Omega_{{\mathrm{m}}}=0.265\pm0.022$ (68% CL). Our limit on $w$ is consistent with and is as tight as that from the distance-alone constraint from the CMB and $H_0$. Finally, by combining the tSZ power spectrum and the CMB data we find, in the $\Lambda$ Cold Dark Matter (CDM) model, the mass bias of $B=1.71\pm 0.17$, i.e., $1-b=0.58\pm 0.06$ (68% CL)., Comment: Accepted version (MNRAS)

Millimeter-wave continuum astronomy is today an indispensable tool for both general Astrophysics studies and Cosmology. General purpose, large field-of-view instruments are needed to map the sky at intermediate angular scales not accessible by the high-resolution interferometers and by the coarse angular resolution space-borne or ground-based surveys. These instruments have to be installed at the focal plane of the largest single-dish telescopes. In this context, we have constructed and deployed a multi-thousands pixels dual-band (150 and 260 GHz, respectively 2mm and 1.15mm wavelengths) camera to image an instantaneous field-of-view of 6.5arc-min and configurable to map the linear polarization at 260GHz. We are providing a detailed description of this instrument, named NIKA2 (New IRAM KID Arrays 2), in particular focusing on the cryogenics, the optics, the focal plane arrays based on Kinetic Inductance Detectors (KID) and the readout electronics. We are presenting the performance measured on the sky during the commissioning runs that took place between October 2015 and April 2017 at the 30-meter IRAM (Institut of Millimetric Radio Astronomy) telescope at Pico Veleta. NIKA2 has been successfully deployed and commissioned, performing in-line with the ambitious expectations. In particular, NIKA2 exhibits FWHM angular resolutions of around 11 and 17.5 arc-seconds at respectively 260 and 150GHz. The NEFD (Noise Equivalent Flux Densities) demonstrated on the maps are, at these two respective frequencies, 33 and 8 mJy*sqrt(s). A first successful science verification run has been achieved in April 2017. The instrument is currently offered to the astronomical community during the coming winter and will remain available for at least the next ten years., Comment: Accepted for publication on Astronomy & Astrophysics, in press

Whithin the framework of the Planck satellite polarisation calibration, we present a study of the Crab Nebula spectral energy distribution (SED) over more than 6 decades in frequency ranging from 1 to $\rm 10^6 GHz$. The Planck satellite mission observes the sky from 30 to 857 GHz and therefore we focus on the millimetre region. We use radio and submillimetre data from the WMAP satellite between 23 and 94 GHz (from 13 to 3.18 mm) and from the Archeops balloon experiment between 143 (2.1 mm) and 545 GHz (0.55 mm), and a compendium of other Crab Nebula observations. The Crab SED is compared to models including three main components : synchrotron which is responsible for the emission at low and at high frequencies, dust which explains the excess of flux observed by the IRAS satellite and an extra component on the millimetre regime. From this analysis we conclude that the unpolarised emission of the Crab Nebula at microwave and millimetre wavelengths is the same synchrotron emission that the one observed in the radio domain. Therefore, we expect the millimetre emission of the Crab nebula to be polarised with the same degree of polarisation and orientation than the radio emission. We set upper limits on the possible errors induced by any millimetre extra component on the reconstruction of the degree and angle of polarisation at the percent level as a maximum. This result strongly supports the choice by the Planck collaboration of the Crab nebula emission for performing polarisation cross-checks in the range 30 (299 mm) to 353 GHz (0.849 mm).

We discuss the consistency of constraints in the lambda_0-Omega_0 plane from gravitational lensing statistics, the m-z relation for type Ia supernovae and CMB anisotropies, based on our own (published or unpublished) work and results from the literature., Comment: LaTeX (uses paspconf.sty), 2 pages, no figures. Poster contribution to `Gravitational Lensing: Recent Progress and Future Goals', T. G. Brainerd and C. S. Kochanek (eds.). Paper version available on request. See also http://multivac.jb.man.ac.uk:8000/helbig/research/pubs/info/boston99.html