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Ritacco, A., R. Adam, P. Ade, P. André, A. Andrianasolo, H. Aussel, A. Beelen et al. "The NIKA polarimeter on science targets: Crab nebula observations at 150 GHz and dual-band polarization images of Orion Molecular Cloud OMC-1". EPJ Web of Conferences 228 (2020): 00021. http://dx.doi.org/10.1051/epjconf/202022800021.
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We present here the polarization system of the NIKA camera and give a summary of the main results obtained and performed studies on Orion and the Crab nebula. The polarization system was equipped with a room temperature continuously rotating multi-mesh half wave plate and a grid polarizer facing the NIKA cryostat window. NIKA even though less sensitive than NIKA2 had polarization capability in both 1 and 2 millimiter bands. NIKA polarization observations demonstrated the ability of such a technology in detecting the polarization of different targets, compact and extended sources like the Crab nebula and Orion Molecular Cloud region OMC-1. These measurements together with the developed techniques to deal with systematics, opened the way to the current observations of NIKA2 in polarization that will provide important advances in the studies of galactic and extra-galactic emission and magnetic fields.
2
Ritacco, A., N. Ponthieu, A. Catalano, R. Adam, P. Ade, P. André, A. Beelen et al. "Polarimetry at millimeter wavelengths with the NIKA camera: calibration and performance". Astronomy & Astrophysics 599 (23 de febrero de 2017): A34. http://dx.doi.org/10.1051/0004-6361/201629666.
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Magnetic fields, which play a major role in a large number of astrophysical processes can be traced via observations of dust polarization. In particular, Planck low-resolution observations of dust polarization have demonstrated that Galactic filamentary structures, where star formation takes place, are associated to well organized magnetic fields. A better understanding of this process requires detailed observations of galactic dust polarization on scales of 0.01 to 0.1 pc. Such high-resolution polarization observations can be carried out at the IRAM 30 m telescope using the recently installed NIKA2 camera, which features two frequency bands at 260 and 150 GHz (respectively 1.15 and 2.05 mm), the 260 GHz band being polarization sensitive. NIKA2 so far in commissioning phase, has its focal plane filled with ~3300 detectors to cover a Field of View (FoV) of 6.5 arcmin diameter. The NIKA camera, which consisted of two arrays of 132 and 224 Lumped Element Kinetic Inductance Detectors (LEKIDs) and a FWHM (Full-Width-Half-Maximum) of 12 and 18.2 arcsec at 1.15 and 2.05 mm respectively, has been operated at the IRAM 30 m telescope from 2012 to 2015 as a test-bench for NIKA2. NIKA was equipped of a room temperature polarization system (a half wave plate (HWP) and a grid polarizer facing the NIKA cryostat window). The fast and continuous rotation of the HWP permits the quasi simultaneous reconstruction of the three Stokes parameters, I, Q, and U at 150 and 260 GHz. This paper presents the first polarization measurements with KIDs and reports the polarization performance of the NIKA camera and the pertinence of the choice of the polarization setup in the perspective of NIKA2. We describe the polarized data reduction pipeline, specifically developed for this project and how the continuous rotation of the HWP permits to shift the polarized signal far from any low frequency noise. We also present the dedicated algorithm developed to correct systematic leakage effects. We report results on compact and extended sources obtained duringthe February 2015 technical campaign. These results demonstrate a good understanding of polarization systematics and state-of-the-art performance in terms of photometry, polarization degree and polarization angle reconstruction.
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Pisano, G., A. Ritacco, A. Monfardini, C. Tucker, P. A. R. Ade, A. Shitvov, A. Benoit et al. "Development and application of metamaterial-based half-wave plates for the NIKA and NIKA2 polarimeters". Astronomy & Astrophysics 658 (27 de enero de 2022): A24. http://dx.doi.org/10.1051/0004-6361/202038643.
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Context. Large field-of-view imaging and polarimetry instruments operating at millimetre and sub-millimetre wavelengths are fundamental tools to understand the role of magnetic fields in channelling filament material into prestellar cores, providing unique insight in the physics of galactic star-forming regions. Among other topics, at extra-galactic scales, polarisation observations of Active Galactic Nuclei (AGNs) will allow us to constrain the possible physical conditions of the emitting plasma from the jets and/or explore the physics of dust inside supernova remnants. The kilo-pixel New IRAM KIDs Array 2 (NIKA2) camera, installed today at the Institut de Radioastronomie Millimétrique (IRAM) 30-m telescope, represents one of the best tools available to astronomers to produce simultaneous intensity and polarimetry maps over large fields at 260 GHz (1.15 mm). Aims. The polarisation measurement, in NIKA and NIKA2, is achieved by rapidly modulating the total incoming polarisation. In the end, this allows one to safely isolate the small science signal from the large, un-polarised, and strongly variable, atmospheric background. Methods. The polarisation modulation is achieved by inserting a fast rotating half-wave plate (HWP) in the optical beam. In order to allow wide field-of-view observations, the plate has to be large, with a diameter of 250 mm. The modulation of the polarised signal at 12 Hz also requires the waveplate to be sufficiently light. In addition, this key optical element has to exhibit optimal electromagnetic characteristics in terms of transmission and differential phase-shift. For this purpose, three metamaterial HWPs have been developed using the mesh-filter technology. The knowledge acquired in developing the first two single-band HWPs was used to achieve the more challenging performance requirements of the last dual-band HWP. The first and the third waveplates met the requirements for both the NIKA and NIKA2 instruments. Results. We first illustrate the design, the technical developments, the fabrication, and laboratory characterisation of the three mesh-HWPs. The deployment of two such elements in the NIKA and NIKA2 instruments at the 30-metre telescope is then described. We conclude with representative examples of astrophysical maps integrating polarimetry.
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Ajeddig, H., R. Adam, P. Ade, Ph André, A. Andrianasolo, H. Aussel, A. Beelen et al. "Preliminary results on the instrumental polarization of NIKA2-Pol at the IRAM 30m telescope". EPJ Web of Conferences 228 (2020): 00002. http://dx.doi.org/10.1051/epjconf/202022800002.
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Clarifying the role of magnetic fields in the star formation process is crucial. Observations have already shown that magnetic fields play an important role in the early stages of star formation. The high spatial resolution (∼0.01 to 0.05 pc) provided by NIKA2-Pol 1.2 mm imaging polarimetry of nearby clouds will help us clarify the geometry of the B-field within dense cores and molecular filaments as part of the IRAM 30m large program B-FUN. There are numerous challenging issues in the validation of NIKA2-Pol such as the calibration of instrumental polarization. The commissioning phase of NIKA2-Pol is underway and is helping us characterize the intensity-to-polarization “leakage” pattern of the instrument. We present a preliminary analysis of the leakage pattern and its dependence with elevation. We also present the current leakage correction made possible by the NIKA2 pipeline in polarization mode based on the NIKA2-Pol commissioning data taken in December 2018. Based on reduced Stokes I, Q, U data we find that the leakage pattern of NIKA2-Pol depends on elevation and is sensitive to the focus of the telescope.
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Muñoz-Echeverría, M., R. Adam, P. Ade, H. Ajeddig, P. André, M. Arnaud, E. Artis et al. "The LPSZ-CLASH galaxy cluster sample: Combining lensing and hydrostatic mass estimates". EPJ Web of Conferences 257 (2022): 00033. http://dx.doi.org/10.1051/epjconf/202225700033.
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Starting from the clusters included in the NIKA sample and in the NIKA2 Sunyaev-Zel’dovich Large Program (LPSZ) we have selected a sample of six common objects with the Cluster Lensing And Supernova survey with Hubble (CLASH) lensing data. For the LPSZ clusters we have at our disposal both high-angular resolution observations of the thermal SZ with NIKA and NIKA2 and X-ray observations with XMM-Newton from which hydrostatic mass estimates can be derived. In addition, the CLASH dataset includes lensing convergence maps that can be converted into lensing estimates of the total mass of the cluster. One-dimensional mass profiles are used to derive integrated mass estimates accounting for systematic effects (data processing, modeling, etc.). Two-dimensional analysis of the maps can reveal substructures in the cluster and, therefore, inform us about the dynamical state of each system. Moreover, we are able to study the hydrostatic mass to lensing mass bias, across different morphology and a range of redshift clusters to give more insight on the hydrostatic mass bias. The analysis presented in this proceeding follows the study discussed in [20].
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Kéruzoré, F., F. Mayet, G. W. Pratt, R. Adam, P. Ade, P. André, A. Andrianasolo et al. "Exploiting NIKA2/XMM-Newton imaging synergy for intermediate-mass high-z galaxy clusters within the NIKA2 SZ large program". Astronomy & Astrophysics 644 (diciembre de 2020): A93. http://dx.doi.org/10.1051/0004-6361/202038933.
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High-resolution mapping of the intracluster medium (ICM) up to high redshift and down to low masses is crucial to derive accurate mass estimates of the galaxy cluster and to understand the systematic effects affecting cosmological studies based on galaxy clusters. We present a spatially resolved Sunyaev-Zel’dovich (SZ)/X-ray analysis of ACT-CL J0215.4+0030, a high-redshift (z = 0.865) galaxy cluster of intermediate mass (M500 ≃ 3.5 × 1014 M⊙) observed as part of the ongoing NIKA2 SZ large program, which is a follow-up of a representative sample of objects at 0.5 ≤ z ≤ 0.9. In addition to the faintness and small angular size induced by its mass and redshift, the cluster is contaminated by point sources that significantly affect the SZ signal. This is therefore an interesting case study for the most challenging sources of the NIKA2 cluster sample. We present the NIKA2 observations of this cluster and the resulting data. We identified the point sources that affect the NIKA2 maps of the cluster as submillimeter galaxies with counterparts in catalogs of sources constructed by the SPIRE instrument on board the Herschel observatory. We reconstructed the ICM pressure profile by performing a joint analysis of the SZ signal and of the point-source component in the NIKA2 150 GHz map. This cluster is a very weak source that lies below the selection limit of the Planck catalog. Nonetheless, we obtained high-quality estimates of the ICM thermodynamical properties with NIKA2. We compared the pressure profile extracted from the NIKA2 map to the pressure profile obtained from X-ray data alone by deprojecting the public XMM-Newton observations of the cluster. We combined the NIKA2 pressure profile with the X-ray deprojected density to extract detailed information on the ICM. The radial distribution of its thermodynamic properties (the pressure, temperature and entropy) indicate that the cluster has a highly disturbed core. We also computed the hydrostatic mass of the cluster, which is compatible with estimations from SZ and X-ray scaling relations. We conclude that the NIKA2 SZ large program can deliver quality information on the thermodynamics of the ICM even for one of its faintest clusters after a careful treatment of the contamination by point sources.
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Lefèvre, Charlène, Carsten Kramer, Roberto Neri, Stefano Berta y Karl Schuster. "NOEMA complementarity with NIKA2". EPJ Web of Conferences 228 (2020): 00014. http://dx.doi.org/10.1051/epjconf/202022800014.
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IRAM operates two observatories - the 30-meter Telescope on Pico Veleta in Spain and NOEMA, an interferometer of ten 15-meter antennas on Plateau de Bure in France. Both observatories allow to observe at millimeter wavelengths. Here, we aim at discussing the complementary between continuum observations with NOEMA and NIKA2 at the 30m and their role at the cutting edge of research in astronomy. In particular, we will review possible synergies of continuum studies from nearby star forming regions to high red-shift galaxies at cosmological distances.
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Mayet, F., R. Adam, P. Ade, P. André, A. Andrianasolo, M. Arnaud, H. Aussel et al. "Cluster cosmology with the NIKA2 SZ Large Program". EPJ Web of Conferences 228 (2020): 00017. http://dx.doi.org/10.1051/epjconf/202022800017.
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The main limiting factor of cosmological analyses based on thermal Sunyaev-Zel’dovich (SZ) cluster statistics comes from the bias and systematic uncertainties that affect the estimates of the mass of galaxy clusters. High-angular resolution SZ observations at high redshift are needed to study a potential redshift or morphology dependence of both the mean pressure profile and of the mass-observable scaling relation used in SZ cosmological analyses. The NIKA2 camera is a new generation continuum instrument installed at the IRAM 30-m telescope. With a large field of view, a high angular resolution and a high-sensitivity, the NIKA2 camera has unique SZ mapping capabilities. In this paper, we present the NIKA2 SZ large program, aiming at observing a large sample of clusters at redshifts between 0.5 and 0.9, and the characterization of the first cluster oberved with NIKA2.
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Ritacco, A., R. Adam, P. Ade, H. Ajeddig, P. André, A. Andrianasolo, H. Aussel et al. "Observing with NIKA2Pol from the IRAM 30m telescope : Early results on the commissioning phase". EPJ Web of Conferences 228 (2020): 00022. http://dx.doi.org/10.1051/epjconf/202022800022.
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The NIKA2 polarization channel at 260 GHz (1.15 mm) has been proposed primarily to observe galactic star-forming regions and probe the critical scales between 0.01-0.05 pc at which magnetic field lines may channel the matter of interstellar filaments into growing dense cores. The NIKA2 polarime-ter consists of a room temperature continuously rotating multi-mesh HWP and a cold polarizer that separates the two orthogonal polarizations onto two 260 GHz KIDs arrays. We describe in this paper the preliminary results obtained during the most recent commissioning campaign performed in December 2018. We concentrate here on the analysis of the extended sources, while the observation of compact sources is presented in a companion paper [12]. We present preliminary NIKA2 polarization maps of the Crab nebula. We find that the integrated polarization intensity flux measured by NIKA2 is consistent with expectations. In terms of polarization angle, we are still limited by systematic uncertainties that will be further investigated in the forthcoming commissioning campaigns.
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De Petris, Marco, Florian Ruppin, Federico Sembolini, Remí Adam, Anna Silvia Baldi, Giammarco Cialone, Barbara Comis et al. "Confirmation of NIKA2 investigation of the Sunyaev-Zel’dovich effect by using synthetic clusters of galaxies". EPJ Web of Conferences 228 (2020): 00008. http://dx.doi.org/10.1051/epjconf/202022800008.
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The NIKA2 Sunyaev-Zel’dovich Large Program (SZLP) is focused on mapping the thermal SZ signal of a representative sample of selected Planck and ACT clusters spanning the redshift range 0.5 < z < 0.9. Hydrodynamical N-body simulations prove to be a powerful tool to endorse NIKA2 capabilities for estimating the impact of IntraCluster Medium (ICM) disturbances when re- covering the pressure radial profiles. For this goal we employ a subsample of objects, carefully extracted from the catalog Marenostrum MUltidark SImulations of galaxy Clusters (MUSIC), spanning equivalent redshift and mass ranges as the LPSZ. The joint analysis of real observations of the tSZ with NIKA2 and Planck enables to validate the NIKA2 pipeline and to estimate the ICM pressure profiles. Moreover, the possibility to identify a priori the dynamical state of the selected synthetic clusters allows us to verify the impact on the recovered ICM profile shapes and their scatters. Morphological analysis of maps of the Compton parameter seems to be a way to observationally segregate the sample based on the dynamical state in relaxed and disturbed synthetic clusters.
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Ruppin, F., F. Sembolini, M. De Petris, R. Adam, G. Cialone, J. F. Macías-Pérez, F. Mayet, L. Perotto y G. Yepes. "Impact of ICM disturbances on the mean pressure profile of galaxy clusters: A prospective study of the NIKA2 SZ large program with MUSIC synthetic clusters". Astronomy & Astrophysics 631 (15 de octubre de 2019): A21. http://dx.doi.org/10.1051/0004-6361/201935059.
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Context. The mean pressure profile of the galaxy cluster population plays an essential role in cosmological analyses. An accurate characterization of the shape, intrinsic scatter, and redshift evolution of this profile is necessary to estimate some of the biases and systematic effects that currently prevent cosmological analyses based on thermal Sunyaev-Zel’dovich (tSZ) surveys from obtaining precise and unbiased cosmological constraints. This is one of the main goals of the ongoing NIKA2 SZ large program, which aims at mapping the tSZ signal of a representative cluster sample selected from the Planck and ACT catalogs and spans a redshift range 0.5 < z < 0.9. Aims. To estimate the impact of intracluster medium (ICM) disturbances that can be detected by NIKA2 on the mean pressure profile of galaxy clusters, we realized a study based on a synthetic cluster sample that is similar to that of the NIKA2 SZ large program. Methods. To reach this goal we employed the hydrodynamical N-body simulation Marenostrum MUltidark SImulations of galaxy Clusters (MUSIC). We simulated realistic NIKA2 and Planck tSZ observations, which were jointly analyzed to estimate the ICM pressure profile of each cluster. A comparison of the deprojected profiles with the true radial profiles directly extracted from the MUSIC simulation allowed us to validate the NIKA2 tSZ pipeline and to study the impact of ICM disturbances on the characterization of the ICM pressure distribution even at high redshift. After normalizing each profile by the integrated quantities estimated under the hydrostatic equilibrium hypothesis, we evaluated the mean pressure profile of the twin sample and show that it is compatible with that extracted directly from the MUSIC simulation in the scale range that can be recovered by NIKA2. We studied the impact of cluster dynamical state on both its shape and associated scatter. Results. We observe that at R500 the scatter of the distribution of normalized pressure profiles associated with the selected morphologically disturbed clusters is 65% larger than that associated with relaxed clusters. Furthermore, we show that using a basic modeling of the thermal pressure distribution in the deprojection procedure induces a significant increase of the scatter associated with the mean normalized pressure profile compared to the true distribution extracted directly from the simulation. Conclusions. We conclude that the NIKA2 SZ large program will facilitate characterization of the potential redshift evolution of the mean pressure profile properties due to the performance of the NIKA2 camera, thereby allowing for a precise measurement of cluster morphology and ICM thermodynamic properties up to R500 at high redshift.
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Kéruzoré, F., R. Adam, P. Ade, P. André, A. Andrianasolo, M. Arnaud, H. Aussel et al. "A low-mass galaxy cluster as a test-case study for the NIKA2 SZ Large Program". EPJ Web of Conferences 228 (2020): 00012. http://dx.doi.org/10.1051/epjconf/202022800012.
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High-resolution mapping of the hot gas in galaxy clusters is a key tool for cluster-based cosmological analyses. Taking advantage of the NIKA2 millimeter camera operated at the IRAM 30-m telescope, the NIKA2 SZ Large Program seeks to get a high-resolution follow-up of 45 galaxy clusters covering a wide mass range at high redshift in order to re-calibrate some of the tools needed for the cosmological exploitation of SZ surveys. We present the second cluster analysis of this program, targeting one of the faintest sources of the sample in order to tackle the difficulties in data reduction for such faint, low-SNR clusters. In this study, the main challenge is the precise estimation of the contamination by sub-millimetric point sources, which greatly affects the tSZ map of the cluster. We account for this contamination by performing a joint fit of the SZ signal and of the flux density of the compact sources. A prior knowledge of these fluxes is given by the adjustment of the SED of each source using data from both NIKA2 and the Herschel satellite. The first results are very promising and demonstrate the possibility to estimate thermodynamic properties with NIKA2, even in a compact cluster heavily contaminated by point sources.
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Perotto, L., R. Adam, P. Ade, H. Ajeddig, P. André, E. Artis, H. Aussel et al. "The NIKA2 Sunyaev-Zeldovich Large Program". EPJ Web of Conferences 293 (2024): 00040. http://dx.doi.org/10.1051/epjconf/202429300040.
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The NIKA2 camera operating at the IRAM 30-m telescope excels in high-angular resolution mapping of the thermal Sunyaev-Zel’dovich effect towards galaxy clusters at intermediate and high-redshift. As part of the NIKA2 guaranteed-time, the SZ Large Program (LPSZ) aims at tSZ-mapping a representative sample of SZ-selected galaxy clusters in the catalogues of the Planck satellite and of the Atacama Cosmology Telescope, and also observed in X-ray with XMM-Newton or Chandra. Having completed observations in January 2023, we present tSZ maps of 38 clusters spanning the targeted mass (3 < M500/1014M⊙ < 10) and redshift (0.5 < z < 0.9) range. The first in-depth studies of individual clusters highlight the potential of combining tSZ and X-ray observations at similar angular resolution for precised mass measurements under the hydrostatic assumption MHSE. These were milestones for the development of a standard data analysis pipeline to go from NIKA2 raw data to the thermodynamic properties of galaxy clusters for the upcoming LPSZ data release. Final products will include measurements of the mean pressure profile of unprecedented quality and MHSE-observable scaling relation using a distinctive SZ-selected sample, which will be key for ultimately improving the accuracy of cluster-based cosmology.
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Roussel, H., N. Ponthieu, R. Adam, P. Ade, P. André, A. Andrianasolo, H. Aussel et al. "NIKA2 mapping and cross-instrument SED extraction of extended sources with Scanamorphos". EPJ Web of Conferences 228 (2020): 00024. http://dx.doi.org/10.1051/epjconf/202022800024.
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The steps taken to tailor to NIKA2 observations the Scanamorphos algorithm (initially developed to subtract low-frequency noise from Herschel on-the-fly observations) are described, focussing on the consequences of the different instrument architecture and observation strategy. The method, making the most extensive use of the redundancy built in the multi-scan coverage with large arrays of a given region of the sky, is applicable to extended sources, while the pipeline is so far optimized for compact sources. An example of application is given. A related tool to build consistent broadband SEDs from 60 microns to 2 mm, combining Herschel and NIKA2 data, has also been developed. Its main task is to process the data least affected by low-frequency noise and coverage limitations (i.e. the Herschel data) through the same transfer function as the NIKA2 data, simulating the same scan geometry and applying the same noise and atmospheric signal as extracted from the 1mm and 2mm data.
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Ruppin, F., F. Mayet, G. W. Pratt, R. Adam, P. Ade, P. André, M. Arnaud et al. "First Sunyaev–Zel’dovich mapping with the NIKA2 camera: Implication of cluster substructures for the pressure profile and mass estimate". Astronomy & Astrophysics 615 (julio de 2018): A112. http://dx.doi.org/10.1051/0004-6361/201732558.
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The complete characterization of the pressure profile of high-redshift galaxy clusters, from their core to their outskirts, is a major issue for the study of the formation of large-scale structures. It is essential to constrain a potential redshift evolution of both the slope and scatter of the mass-observable scaling relations used in cosmology studies based on cluster statistics. In this paper, we present the first thermal Sunyaev–Zel’dovich (tSZ) mapping of a cluster from the sample of the New IRAM Kids Arrays (NIKA2) SZ large program that aims at constraining the redshift evolution of cluster pressure profiles and the tSZ-mass scaling relation. We observed the galaxy cluster PSZ2 G144.83+25.11 at redshift z = 0.58 with the NIKA2 camera, a dual-band (150 and 260 GHz) instrument operated at the Institut de Radioastronomie Millimtrique (IRAM) 30-m telescope. We identify a thermal pressure excess in the south-west region of PSZ2 G144.83+25.11 and a high-redshift sub-millimeter point source that affect the intracluster medium (ICM) morphology of the cluster. The NIKA2 data are used jointly with tSZ data acquired by the Multiplexed SQUID/TES Array at Ninety Gigahertz (MUSTANG), Bolocam, and Planck experiments in order to non-parametrically set the best constraints on the electronic pressure distribution from the cluster core (R ~ 0.02R500) to its outskirts (R ~ 3R500). We investigate the impact of the over-pressure region on the shape of the pressure profile and on the constraints on the integrated Compton parameter Y500. A hydrostatic mass analysis is also performed by combining the tSZ-constrained pressure profile with the deprojected electronic density profile from XMM-Newton. This allows us to conclude that the estimates of Y500 and M500 obtained from the analysis with and without masking the disturbed ICM region differ by 65% and 79%, respectively. This work highlights that NIKA2 will have a crucial impact on the characterization of the scatter of the Y500−M500 scaling relation due to its high potential to constrain the thermodynamic and morphological properties of the ICM when used in synergy with X-ray observations of similar angular resolution. This study also presents the typical products that will be delivered to the community for all clusters included in the NIKA2 tSZ Large Program.
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Muñoz-Echeverría, M., R. Adam, P. Ade, H. Ajeddig, P. André, M. Arnaud, E. Artis et al. "Multi-probe analysis of the galaxy cluster CL J1226.9+3332: Hydrostatic mass and hydrostatic-to-lensing bias". EPJ Web of Conferences 257 (2022): 00032. http://dx.doi.org/10.1051/epjconf/202225700032.
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We present a multi-probe analysis of the well-known galaxy cluster CL J1226.9+3332 as a proof of concept for multi-wavelength studies within the framework of the NIKA2 Sunyaev-Zel’dovich Large Program (LPSZ). CL J1226.9+3332 is a massive and high redshift (z = 0.888) cluster that has already been observed at several wavelengths. A joint analysis of the thermal SZ (tSZ) effect at millimeter wavelength with the NIKA2 camera and in X-ray with the XMM-Newton satellite permits the reconstruction of the cluster’s thermodynamical properties and mass assuming hydrostatic equilibrium. We test the robustness of our mass estimates against different definitions of the data analysis transfer function. Using convergence maps reconstructed from the data of the CLASH program we obtain estimates of the lensing mass, which we compare to the estimated hydrostatic mass. This allows us to measure the hydrostatic-to-lensing mass bias and the associated systematic effects related to the NIKA2 measurement. We obtain M500HSE = (7:65 ± 1:03) × 1014M⊙ and M500lens = (7:35 ± 0:65) × 1014M⊙, which implies a HSE-to-lensing bias consistent with 0 within 20%.
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Perotto, L., R. Adam, P. Ade, H. Ajeddig, P. André, M. Arnaud, E. Artis et al. "The NIKA2 Sunyaev-Zeldovich Large Program: Precise galaxy cluster physics for an accurate cluster-based cosmology". EPJ Web of Conferences 257 (2022): 00038. http://dx.doi.org/10.1051/epjconf/202225700038.
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The NIKA2 Guaranteed-Time SZ Large Program (LPSZ) is dedicated to the high-angular resolution SZ mapping of a representative sample of 45 SZ-selected galaxy clusters drawn from the catalogues of the Planck satellite, or of the Atacama Cosmology Telescope. The LPSZ sample spans a mass range from 3 to 11 × 1014M⊙ and a redshift range from 0:5 to 0:9, extending to higher redshift and lower mass the previous samples dedicated to the cluster mass calibration and universal properties estimation. The main goals of the LPSZ are the measurement of the average radial profile of the ICM pressure up to R500 by combining NIKA2 with Planck or ACT data, and the estimation of the scaling law between the SZ observable and the mass using NIKA2, XMM-Newton and Planck/ACT data. Furthermore, combining LPSZ data with existing or forthcoming public data in lensing, optical/NIR or radio domains, we will build a consistent picture of the cluster physics and further gain knowledge on the mass estimate as a function of the cluster morphology and dynamical state. We give an overview of the LPSZ, present recent results and discuss the future implication for cosmology with galaxy clusters.
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Galliano, Frédéric. "Cosmic dust evolution: The challenges for NIKA2". EPJ Web of Conferences 257 (2022): 00019. http://dx.doi.org/10.1051/epjconf/202225700019.
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I summarize a recent study aimed at constraining dust evolution timescales in nearby galaxies. We were able to quantify the effciency of dust condensation in SN II ejecta, grain growth in the ISM and dust destruction by SN II blast waves. Around Solar metallicity, our results are consistent with what we know in the Milky Way, that is dust production is dominated by grain growth. We however show that this changes with metallicity. The dust content in very-low-metallicity systems is dominated by grains that have formed in SN II ejecta. I end this article with a discussion about the potential of NIKA2 to study dust evolution in galaxies.
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Bourrion, O., A. Benoit, J. L. Bouly, J. Bouvier, G. Bosson, M. Calvo, A. Catalano et al. "NIKEL_AMC: readout electronics for the NIKA2 experiment". Journal of Instrumentation 11, n.º 11 (4 de noviembre de 2016): P11001. http://dx.doi.org/10.1088/1748-0221/11/11/p11001.
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Shu, S., M. Calvo, S. Leclercq, J. Goupy, A. Monfardini y E. F. C. Driessen. "Prototype High Angular Resolution LEKIDs for NIKA2". Journal of Low Temperature Physics 193, n.º 3-4 (26 de junio de 2018): 141–48. http://dx.doi.org/10.1007/s10909-018-1997-x.
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Ricardo Rizzo, J., Alessia Ritacco y Cristobal Bordiu. "NIKA2 observations around LBV stars Emission from stars and circumstellar material". EPJ Web of Conferences 228 (2020): 00023. http://dx.doi.org/10.1051/epjconf/202022800023.
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Luminous Blue Variable (LBV) stars are evolved massive objects, previous to core-collapse supernova. LBVs are characterized by photometric and spectroscopic variability, produced by strong and dense winds, mass-loss events and very intense UV radiation. LBVs strongly disturb their surroundings by heating and shocking, and produce important amounts of dust. The study of the circumstellar material is therefore crucial to understand how these massive stars evolve, and also to characterize their effects onto the interstellar medium. The versatility of NIKA2 is a key in providing simultaneous observations of both the stellar continuum and the extended, circumstellar contribution. The NIKA2 frequencies (150 and 260 GHz) are in the range where thermal dust and free-free emission compete, and hence NIKA2 has the capacity to provide key information about the spatial distribution of circumstellar ionized gas, warm dust and nearby dark clouds; non-thermal emission is also possible even at these high frequencies. We show the results of the first NIKA2 survey towards five LBVs. We detected emission from four stars, three of them immersed in tenuous circumstellar material. The spectral indices show a complex distribution and allowed us to separate and characterize different components. We also found nearby dark clouds, with spectral indices typical of thermal emission from dust. Spectral indices of the detected stars are negative and hard to be explained only by free-free processes. In one of the sources, G79.29+0.46, we also found a strong correlation of the 1mm and 2mm continuum emission with respect to nested molecular shells at ≈1 pc from the LBV. The spectral index in this region clearly separates four components: the LBV star, a bubble characterized by free-free emission, and a shell interacting with a nearby infrared dark cloud.
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Nersesian, A., R. Adam, P. Ade, H. Ajeddig, P. André, E. Artis, H. Aussel et al. "Stellar and dust emission profiles of IMEGIN galaxies". EPJ Web of Conferences 293 (2024): 00034. http://dx.doi.org/10.1051/epjconf/202429300034.
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We present a morphological analysis of a set of spiral galaxies from the NIKA2 Guaranteed Time Large Program, IMEGIN. We have fitted a single Sérsic model on a set of broadband images, from ultra-violet (UV) to millimeter (mm) wavelengths, using the modelling code Statmorph. With the recently acquired NIKA2 1.15- and 2-mm observations, it is possible to extend such a morphological analysis to the mm regime and investigate the two-dimensional (2D) distribution (exponential, Gaussian) of the very cold dust (<15 K). We show preliminary results of the 2D large-scale distribution of stars and dust in spiral galaxies, how they relate to each other, and highlight how they differ from galaxy to galaxy.
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Katsioli, S., R. Adam, P. Ade, H. Ajeddig, P. André, E. Artis, H. Aussel et al. "Exploring the millimetre emission in nearby galaxies: Analysis of the edge-on galaxy NGC 891". EPJ Web of Conferences 257 (2022): 00023. http://dx.doi.org/10.1051/epjconf/202225700023.
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New observations of the edge-on galaxy NGC 891, at 1.15 and 2mm obtained with the IRAM 30-m telescope and the NIKA2 camera, within the framework of the IMEGIN (Interpreting the Millimetre Emission of Galaxies with IRAM and NIKA2) Large Program, are presented in this work. By using multiwavelength maps (from the mid-IR to the cm wavelengths) we perform SED fitting in order to extract the physical properties of the galaxy on both global and local (~kpc) scales. For the interpretation of the observations we make use of a state-of-the-art SED fitting code, HerBIE (HiERarchical Bayesian Inference for dust Emission). The observations indicate a galaxy morphology, at mm wavelengths, similar to that of the cold dust emission traced by submm observations and to that of the molecular gas. The contribution of the radio emission at the NIKA2 bands is very small (negligible at 1.15 mm and ~ 10% at 2 mm) while it dominates the total energy budget at longer wavelengths (beyond 5 mm). On local scales, the distribution of the free-free emission resembles that of the dust thermal emission while the distribution of the synchrotron emission shows a deficiency along the major axis of the disc of the galaxy.
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Ajeddig, H., R. Adam, P. Ade, P. André, E. Artis, H. Aussel, A. Beelen et al. "Probing the role of magnetic fields in star-forming filaments: NIKA2-Pol commissioning results toward OMC-1". EPJ Web of Conferences 257 (2022): 00002. http://dx.doi.org/10.1051/epjconf/202225700002.
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Dust polarization observations are a powerful, practical tool to probe the geometry (and to some extent, the strength) of magnetic fields in starforming regions. In particular, Planck polarization data have revealed the importance of magnetic fields on large scales in molecular clouds. However, due to insufficient resolution, Planck observations are unable to constrain the B-field geometry on prestellar and protostellar scales. The high angular resolution of 11.7 arcsec provided by NIKA2-Pol 1.15 mm polarimetric imaging, corresponding to 0.02 pc at the distance of the Orion molecular cloud (OMC), makes it possible to advance our understanding of the B-field morphology in star-forming filaments and dense cores (IRAM 30m large program B-FUN). The commissioning of the NIKA2-Pol instrument has led to several challenging issues, in particular, the instrumental polarization or intensity-to-polarization “leakage” effect. In the present paper, we illustrate how this effect can be corrected for, leading to reliable exploitable data in a structured, extended source such as OMC-1. We present a statistical comparison between NIKA2-Pol and SCUBA2-Pol2 results in the OMC-1 region. We also present tentative evidence of local pinching of the B-field lines near Orion-KL, in the form of a new small-scale hourglass pattern, in addition to the larger-scale hourglass already seen by other instruments such as Pol2.
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Perotto, L., N. Ponthieu, J. F. Macías-Pérez, R. Adam, P. Ade, P. André, A. Andrianasolo et al. "Calibration and performance of the NIKA2 camera at the IRAM 30-m Telescope". Astronomy & Astrophysics 637 (mayo de 2020): A71. http://dx.doi.org/10.1051/0004-6361/201936220.
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Context. NIKA2 is a dual-band millimetre continuum camera of 2 900 kinetic inductance detectors, operating at 150 and 260 GHz, installed at the IRAM 30-m telescope in Spain. Open to the scientific community since October 2017, NIKA2 will provide key observations for the next decade to address a wide range of open questions in astrophysics and cosmology. Aims. Our aim is to present the calibration method and the performance assessment of NIKA2 after one year of observation. Methods. We used a large data set acquired between January 2017 and February 2018 including observations of primary and secondary calibrators and faint sources that span the whole range of observing elevations and atmospheric conditions encountered by the IRAM 30-m telescope. This allowed us to test the stability of the performance parameters against time evolution and observing conditions. We describe a standard calibration method, referred to as the “Baseline” method, to translate raw data into flux density measurements. This includes the determination of the detector positions in the sky, the selection of the detectors, the measurement of the beam pattern, the estimation of the atmospheric opacity, the calibration of absolute flux density scale, the flat fielding, and the photometry. We assessed the robustness of the performance results using the Baseline method against systematic effects by comparing results using alternative methods. Results. We report an instantaneous field of view of 6.5′ in diameter, filled with an average fraction of 84%, and 90% of valid detectors at 150 and 260 GHz, respectively. The beam pattern is characterised by a FWHM of 17.6″ ± 0.1″ and 11.1″ ± 0.2″, and a main-beam efficiency of 47%±3%, and 64%±3% at 150 and 260 GHz, respectively. The point-source rms calibration uncertainties are about 3% at 150 GHz and 6% at 260 GHz. This demonstrates the accuracy of the methods that we deployed to correct for atmospheric attenuation. The absolute calibration uncertainties are of 5%, and the systematic calibration uncertainties evaluated at the IRAM 30-m reference Winter observing conditions are below 1% in both channels. The noise equivalent flux density at 150 and 260 GHz are of 9 ± 1 mJy s1/2 and 30 ± 3 mJy s1/2. This state-of-the-art performance confers NIKA2 with mapping speeds of 1388 ± 174 and 111 ± 11 arcmin2 mJy−2 h−1 at 150 and 260 GHz. Conclusions. With these unique capabilities of fast dual-band mapping at high (better that 18″) angular resolution, NIKA2 is providing an unprecedented view of the millimetre Universe.
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Lestrade, J. F., J. C. Augereau, M. Booth, R. Adam, P. Ade, P. André, A. Andrianasolo et al. "Debris disks around stars in the NIKA2 era". EPJ Web of Conferences 228 (2020): 00015. http://dx.doi.org/10.1051/epjconf/202022800015.
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The new NIKA2 camera at the IRAM 30m radiotelescope was used to observe three known debris disks in order to constrain the SED of their dust emission in the millimeter wavelength domain. We have found that the spectral index between the two NIKA2 bands (1mm and 2mm) is consistent with the Rayleigh-Jeans regime (λ-2), unlike the steeper spectra (λ-3) measured in the submillimeter-wavelength domain for two of the three disks - around the stars Vega and HD107146. We provide a succesful proof of concept to model this spectral inversion in using two populations of dust grains, those smaller and those larger than a grain radius a0 of 0.5mm. This is obtained in breaking the slope of the size distribution and the functional form of the absorption coefficient of the standard model. The third disk - around the star HR8799 - does not exhibit this spectral inversion but is also the youngest.
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Bing, L., R. Adam, P. Ade, H. Ajeddig, P. André, E. Artis, H. Aussel et al. "Searching for high-z DSFGs with NIKA2 and NOEMA". EPJ Web of Conferences 257 (2022): 00006. http://dx.doi.org/10.1051/epjconf/202225700006.
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As the possible progenitors of passive galaxies at z=2-3, dusty starforming galaxies (DSFGs) at z>4 provide a unique perspective to study the formation, assembly, and early quenching of massive galaxies in the early Universe. The extreme obscuration in optical-IR makes (sub)mm spectral scans the most universal and unbiased way to confirm/exclude the high-z nature of candidate dusty star-forming galaxies. We present here the status of the NIKA2 Cosmological Legacy Survey (N2CLS), which is the deepest wide-area singledish survey in the millimeter searching for high-z DSFGs. We also introduce a joint-analysis method to effciently search for the spectroscopic redshift of high-z DSFGs with noisy spectra and photometric data and present its success in identifying the redshift of DSFGs found in NIKA2 science verification data.
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Lestrade, J. F., R. Adam, P. Ade, H. Ajeddig, P. André, E. Artis, H. Aussel et al. "Overdensity of SubMillimiter Galaxies in the GJ526 Field mapped with the NIKA2 Camera". EPJ Web of Conferences 257 (2022): 00027. http://dx.doi.org/10.1051/epjconf/202225700027.
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Using the NIKA2 dual band millimeter camera installed on the IRAM30m telescope, we have mapped a relatively large field (~ 70 arcmin2) in the direction of the star GJ526 to investigate the nature of the sources found with the MAMBO camera at 1.2 mm ten years earlier. We have found that they must be dust-obscured galaxies (SMGs) in the background beyond the star. The new NIKA2 map at 1.15 mm reveals additional sources and, in fact, an overdensity of SMGs predominantly distributed along a filament-like structure in projection on the sky across the whole observed field. We speculate this might be a cosmic filament at high redshift as revealed in cosmological hydrodynamical simulations. Measurement of spectroscopic redshifts of the SMGs in the candidate filament is required now for a definitive confirmation of the nature of the structure.
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Ejlali, G., R. Adam, P. Ade, H. Ajeddig, P. André, E. Artis, H. Aussel et al. "Dust Emission in Galaxies at Millimeter Wavelengths: Cooling of star forming regions in NGC6946". EPJ Web of Conferences 257 (2022): 00016. http://dx.doi.org/10.1051/epjconf/202225700016.
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Interstellar dust plays an important role in the formation of molecular gas and the heating and cooling of the interstellar medium. The spatial distribution of the mm-wavelength dust emission from galaxies is largely unexplored. The NIKA2 Guaranteed Time Project IMEGIN (Interpreting the Millimeter Emission of Galaxies with IRAM and NIKA2) has recently mapped the mm emission in the grand design spiral galaxy NGC6946. By subtracting the contributions from the free-free, synchrotron, and CO line emission, we map the distribution of the pure dust emission at 1:15mm and 2mm. Separating the arm/interarm regions, we find a dominant 2mm emission from interarms indicating the significant role of the general interstellar radiation field in heating the cold dust. Finally, we present maps of the dust mass, temperature, and emissivity index using the Bayesian MCMC modeling of the spectral energy distribution in NGC6946.
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Ruppin, F., R. Adam, P. Ade, H. Ajeddig, P. André, E. Artis, H. Aussel et al. "Mapping the intracluster medium temperature in the era of NIKA2 and MUSTANG-2". EPJ Web of Conferences 257 (2022): 00043. http://dx.doi.org/10.1051/epjconf/202225700043.
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We present preliminary results from an on-going program that aims at mapping the intracluster medium (ICM) temperature of high redshift galaxy clusters from the MaDCoWS sample using a joint analysis of shallow X-ray data obtained by Chandra and high angular resolution Sunyaev-Zel’dovich (SZ) observations realized with the NIKA2 and MUSTANG-2 cameras. We also present preliminary results from an on-going Open Time program within the NIKA2 collaboration that aims at mapping the ICM temperature of a galaxy cluster at z = 0.45 from the resolved detection of the relativistic corrections to the SZ spectrum. These studies demonstrate how high angular resolution SZ observations will play a major role in the coming decade to push the investigation of ICM dynamics and non-gravitational processes to high redshift before the next generation X-ray observatories come into play.
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Ruppin, F., R. Adam, P. Ade, P. André, A. Andrianasolo, M. Arnaud, H. Aussel et al. "Mapping the gas thermodynamic properties of the massive cluster merger MOO J1142+1527 at z = 1.2". EPJ Web of Conferences 228 (2020): 00026. http://dx.doi.org/10.1051/epjconf/202022800026.
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We present the results of the analysis of the very massive cluster MOO J1142+1527 at a redshift z = 1.2 based on high angular resolution NIKA2 Sunyaev-Zel’dovich (SZ) and Chandra X-ray data. This multi-wavelength analysis enables us to estimate the shape of the temperature profile with unprecedented precision at this redshift and to obtain a map of the gas entropy distribution averaged along the line of sight. The comparison between the cluster morphological properties observed in the NIKA2 and Chandra maps together with the analysis of the entropy map allows us to conclude that MOOJ1142+1527 is an on-going merger hosting a cool-core at the position of the X-ray peak. This work demonstrates how the addition of spatially-resolved SZ observations to low signal-to-noise X-ray data can bring valuable insights on the intracluster medium thermodynamic properties at z > 1.
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De Petris, M., A. Ferragamo y F. Mayet. "Foreword: Observing the mm Universe with the NIKA2 camera". EPJ Web of Conferences 257 (2022): 00001. http://dx.doi.org/10.1051/epjconf/202225700001.
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Mayet, F., A. Catalano, J. F. Macías-Pérez y L. Perotto. "Foreword Observing the mm Universe with the NIKA2 camera". EPJ Web of Conferences 228 (2020): 00001. http://dx.doi.org/10.1051/epjconf/202022800001.
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Moyer-Anin, A., R. Adam, P. Ade, H. Ajeddig, P. André, E. Artis, H. Aussel et al. "Systematic effects on the upcoming NIKA2 LPSZ scaling relation". EPJ Web of Conferences 293 (2024): 00032. http://dx.doi.org/10.1051/epjconf/202429300032.
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In cluster cosmology, cluster masses are the main parameter of interest. They are needed to constrain cosmological parameters through the cluster number count. As the mass is not an observable, a scaling relation is needed to link cluster masses to the integrated Compton parameters Y, i.e. the Sunyaev-Zeldovich observable (SZ). Planck cosmological results obtained with cluster number counts are based on a scaling relation measured with clusters at low redshift (z<0.5) observed in SZ and X-ray. In the SZ Large Program (LPSZ) of the NIKA2 collaboration, the scaling relation will be obtained with a sample of 38 clusters at intermediate to high redshift (0.5 < z < 0.9) and observed at high angular resolution in both SZ and X-ray. Thanks to analytical simulation of LPSZ-like samples, we take into account the LPSZ selection function and correct for its effects. Besides, we show that white and correlated noises in the SZ maps do not affect the scaling relation estimation.
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Kramer, C., R. Adam, P. Ade, H. Ajeddig, P. André, E. Artis, H. Aussel et al. "NIKA2 observations of starless cores in Taurus and Perseus". EPJ Web of Conferences 293 (2024): 00027. http://dx.doi.org/10.1051/epjconf/202429300027.
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Dusty starless cores play an important role in regulating the initial phases of the formation of stars and planets. In their interiors, dust grains coagulate and ice mantles form, thereby changing the millimeter emissivities and hence the ability to cool. We mapped four regions with more than a dozen cores in the nearby Galactic filaments of Taurus and Perseus using the NIKA2 camera at the IRAM 30-meter telescope. Combining the 1mm to 2mm flux ratio maps with dust temperature maps from Herschel allowed to create maps of the dust emissivity index β1,2 at resolutions of 2430 and 5600 a.u. in Taurus and Perseus, respectively. Here, we study the variation with total column densities and environment. β1,2 values at the core centers (Av =12 – 19 mag) vary significantly between ~ 1.1 and 2.3. Several cores show a strong rise of β1,2 from the outskirts at ~ 4 mag to the peaks of optical extinctions, consistent with the predictions of grain models and the gradual build-up of ice mantles on coagulated grains in the dense interiors of starless cores.
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Rigby, A. J., R. Adam, P. Ade, H. Ajeddig, M. Anderson, P. André, E. Artis et al. "Galactic Star Formation with NIKA2 (GASTON): Evidence of mass accretion onto dense clumps". EPJ Web of Conferences 257 (2022): 00041. http://dx.doi.org/10.1051/epjconf/202225700041.
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High-mass stars (m* ≳ 8 M⊙) play a crucial role in the evolution of galaxies, and so it is imperative that we understand how they are formed. We have used the New IRAM KIDs Array 2 (NIKA2) camera on the Institut de Radio Astronomie Millimétrique (IRAM) 30-m telescope to conduct high-sensitivity continuum mapping of ~ 2 deg2 of the Galactic plane (GP) as part of the Galactic Star Formation with NIKA2 (GASTON) large program. We have identified a total of 1467 clumps within our deep 1.15 mm continuum maps and, by using overlapping continuum, molecular line, and maser parallax data, we have determined their distances and physical properties. By placing them upon an approximate evolutionary sequence based upon 8 μm Spitzer imaging, we find evidence that the most massive dense clumps accrete material from their surrounding environment during their early evolution, before dispersing as star formation advances, supporting clump-fed models of high-mass star formation.
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Hanser, C., R. Adam, P. Ade, H. Ajeddig, P. André, E. Artis, H. Aussel et al. "Towards the first mean pressure profile estimate with the NIKA2 Sunyaev-Zeldovich Large Program". EPJ Web of Conferences 293 (2024): 00024. http://dx.doi.org/10.1051/epjconf/202429300024.
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High-resolution mapping of the hot gas in galaxy clusters is a key tool for cluster-based cosmological analyses. Taking advantage of the NIKA2 millimeter camera operated at the IRAM 30-m telescope, the NIKA2 SZ Large Program seeks to get a high-resolution follow-up of 38 galaxy clusters covering a wide mass range at intermediate to high redshift. The measured SZ fluxes will be essential to calibrate the SZ scaling relation and the galaxy clusters mean pressure profile, needed for the cosmological exploitation of SZ surveys. We present in this study a method to infer a mean pressure profile from cluster observations. We have designed a pipeline encompassing the map-making and the thermodynamical properties estimates from maps. We then combine all the individual fits, propagating the uncertainties on integrated quantities, such as R500 or P500, and the intrinsic scatter coming from the deviation to the standard self-similar model. We validate the proposed method on realistic LPSZ-like cluster simulations.
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Katsioli, S., R. Adam, P. Ade, H. Ajeddig, P. André, E. Artis, H. Aussel et al. "Exploring the interstellar medium of NGC 891 at millimeter wavelengths using the NIKA2 camera". EPJ Web of Conferences 293 (2024): 00026. http://dx.doi.org/10.1051/epjconf/202429300026.
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In the framework of the IMEGIN Large Program, we used the NIKA2 camera on the IRAM 30-m telescope to observe the edge-on galaxy NGC 891 at 1.15 mm and 2 mm and at a FWHM of 11.1” and 17.6”, respectively. Multiwavelength data enriched with the new NIKA2 observations fitted by the HerBIE SED code (coupled with the THEMIS dust model) were used to constrain the physical properties of the ISM. Emission originating from the diffuse dust disk is detected at all wavelengths from mid-IR to mm. while mid-lR observations reveal warm dust emission from compact H II regions. Indications of mm excess emission have also been found in the outer parts of the galactic disk. Furthermore, our SED fitting analysis constrained the mass fraction of the small (< 15 Å) dust grains. We found that small grains constitute 9.5% of the total dust mass in the galactic plane, but this fraction increases up to ~ 20% at large distances (|z| > 3 kpc) from the galactic plane.
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Nersesian, Angelos, Maarten Baes y Suzanne C. Madden. "Modelling the cold dust in nearby spiral galaxies with radiative transfer". EPJ Web of Conferences 257 (2022): 00034. http://dx.doi.org/10.1051/epjconf/202225700034.
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Cosmic dust grains are one of the fundamental ingredients of the interstellar medium (ISM). In spite of their small contribution to the total mass budget, dust grains play a significant role in the physical and chemical evolution of galaxies. Over the past decades, a plethora of multi-wavelength data, from UV to far-infrared, has increased substantially our knowledge on the dust properties of nearby galaxies. Nevertheless, one regime of the spectrum, the mm range, remains relatively unexplored. Thanks to the new, high-resolution data in the mm range observed with the NIKA2 instrument and our radiative transfer framework, we aim to firmly characterise the physical properties of the very cold dust (<15K), and to quantify the importance of different emission mechanisms in the mm. So far, we have developed a methodology to use dust radiative transfer modelling and applied it to a small group of face-on spiral galaxies. The combination of the new NIKA2 data with our radiative transfer techniques would provide the right conditions to generate an accurate model of the interplay between starlight and dust in a sizeable sample of spatiallyresolved nearby galaxies.
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Nguyen-Luong, Q., R. Adam, P. Ade, H. Ajeddig, P. André, E. Artis, H. Aussel et al. "NIKA2 observations of dust grain evolution from star-forming filament to T-Tauri disk: Preliminary results from NIKA2 observations of the Taurus B211/B213 filament". EPJ Web of Conferences 293 (2024): 00035. http://dx.doi.org/10.1051/epjconf/202429300035.
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To understand the evolution of dust properties in molecular clouds in the course of the star formation process, we constrain the changes in the dust emissivity index from star-forming filaments to prestellar and protostellar cores to T Tauri stars. Using the NIKA2 continuum camera on the IRAM 30 m telescope. we observed the Taurus B211/B2I3 filament at 1.2 mm and 2 mm with unprecedented sensitivity and used the resulting maps to derive the dust emissivity index β. Our sample of 105 objects detected in the β map of the B211/B213 filament indicates that, overal. β decreases from filament and prestellar cores (β ~ 2 ± 0.5) to protostellar cores (β ~ 1.2 ± 0.2) to T-Tauri protoplanetary disk (β < I). The averaged dust emissivity index β across the B211/B2I3 filament exhibits a flat (β ~ 2 ± 0.3) profile. This may imply that dust grain sizes are rather homogeneous in the filament, start to grow significantly in size only after the onset of the gravitational contraction/collapse of prestellar cores to protostars, reaching big sizes in T Tauri protoplanetary disks. This evolution from the parent filament to T-Tauri disks happens on a timescale of about 1-2 Myr.
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Goupy, J., A. Adane, A. Benoit, O. Bourrion, M. Calvo, A. Catalano, G. Coiffard et al. "Microfabrication Technology for Large Lekid Arrays: From Nika2 to Future Applications". Journal of Low Temperature Physics 184, n.º 3-4 (8 de febrero de 2016): 661–67. http://dx.doi.org/10.1007/s10909-016-1531-y.
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Catalano, A., R. Adam, P. A. R. Ade, P. André, H. Aussel, A. Beelen, A. Benoît et al. "The NIKA2 Instrument at 30-m IRAM Telescope: Performance and Results". Journal of Low Temperature Physics 193, n.º 5-6 (19 de marzo de 2018): 916–22. http://dx.doi.org/10.1007/s10909-018-1884-5.
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Ricci, M., R. Adam, D. Eckert, P. Ade, P. André, A. Andrianasolo, B. Altieri et al. "The XXL Survey". Astronomy & Astrophysics 642 (octubre de 2020): A126. http://dx.doi.org/10.1051/0004-6361/201937249.
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High-mass clusters at low redshifts have been intensively studied at various wavelengths. However, while more distant objects at lower masses constitute the bulk population of future surveys, their physical state remain poorly explored to date. In this paper, we present resolved observations of the Sunyaev-Zel’dovich (SZ) effect, obtained with the NIKA2 camera, towards the cluster of galaxies XLSSC 102, a relatively low-mass system (M500 ∼ 2 × 1014 M⊙) at z = 0.97 detected from the XXL survey. We combine NIKA2 SZ data, XMM-Newton X-ray data, and Megacam optical data to explore, respectively, the spatial distribution of the gas electron pressure, the gas density, and the galaxies themselves. We find significant offsets between the X-ray peak, the SZ peak, the brightest cluster galaxy, and the peak of galaxy density. Additionally, the galaxy distribution and the gas present elongated morphologies. This is interpreted as the sign of a recent major merging event, which induced a local boost of the gas pressure towards the north of XLSSC 102 and stripped the gas out of the galaxy group. The NIKA2 data are also combined with XXL data to construct the thermodynamic profiles of XLSSC 102, obtaining relatively tight constraints up to about ∼r500, and revealing properties that are typical of disturbed systems. We also explore the impact of the cluster centre definition and the implication of local pressure substructure on the recovered profiles. Finally, we derive the global properties of XLSSC 102 and compare them to those of high-mass-and-low-redshift systems, finding no strong evidence for non-standard evolution. We also use scaling relations to obtain alternative mass estimates from our profiles. The variation between these different mass estimates reflects the difficulty to accurately measure the mass of low-mass clusters at z ∼ 1, especially with low signal-to-noise ratio data and for a disturbed system. However, it also highlights the strength of resolved SZ observations alone and in combination with survey-like X-ray data. This is promising for the study of high redshift clusters from the combination of eROSITA and high resolution SZ instruments and will complement the new generation of optical surveys from facilities such as LSST and Euclid.
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Calvo, M., A. Benoît, A. Catalano, J. Goupy, A. Monfardini, N. Ponthieu, E. Barria et al. "The NIKA2 Instrument, A Dual-Band Kilopixel KID Array for Millimetric Astronomy". Journal of Low Temperature Physics 184, n.º 3-4 (16 de marzo de 2016): 816–23. http://dx.doi.org/10.1007/s10909-016-1582-0.
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Adam, R., A. Adane, P. A. R. Ade, P. André, A. Andrianasolo, H. Aussel, A. Beelen et al. "The NIKA2 large-field-of-view millimetre continuum camera for the 30 m IRAM telescope". Astronomy & Astrophysics 609 (enero de 2018): A115. http://dx.doi.org/10.1051/0004-6361/201731503.
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Context. Millimetre-wave continuum astronomy is today an indispensable tool for both general astrophysics studies (e.g. star formation, nearby galaxies) and cosmology (e.g. cosmic microwave background and high-redshift galaxies). General purpose, large-field-of-view instruments are needed to map the sky at intermediate angular scales not accessible by the high-resolution interferometers (e.g. ALMA in Chile, NOEMA in the French Alps) and by the coarse angular resolution space-borne or ground-based surveys (e.g. Planck, ACT, SPT). These instruments have to be installed at the focal plane of the largest single-dish telescopes, which are placed at high altitude on selected dry observing sites. In this context, we have constructed and deployed a three-thousand-pixel dual-band (150 GHz and 260 GHz, respectively 2 mm and 1.15 mm wavelengths) camera to image an instantaneous circular field-of-view of 6.5 arcmin in diameter, and configurable to map the linear polarisation at 260 GHz. Aims. First, we are providing a detailed description of this instrument, named NIKA2 (New IRAM KID Arrays 2), in particular focussing on the cryogenics, optics, focal plane arrays based on Kinetic Inductance Detectors, and the readout electronics. The focal planes and part of the optics are cooled down to the nominal 150 mK operating temperature by means of an adhoc dilution refrigerator. Secondly, 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-m IRAM telescope at Pico Veleta, near Granada (Spain). Methods. We have targeted a number of astronomical sources. Starting from beam-maps on primary and secondary calibrators we have then gone to extended sources and faint objects. Both internal (electronic) and on-the-sky calibrations are applied. The general methods are described in the present paper. Results. NIKA2 has been successfully deployed and commissioned, performing in-line with expectations. In particular, NIKA2 exhibits full width at half maximum angular resolutions of around 11 and 17.5 arcsec at respectively 260 and 150 GHz. The noise equivalent flux densities are, at these two respective frequencies, 33±2 and 8±1 mJy s1/2. A first successful science verification run was achieved in April 2017. The instrument is currently offered to the astronomy community and will remain available for at least the following ten years.
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Bianchi, Simone, Matteo Murgia, Andrea Melis, Viviana Casasola, Maud Galametz, Frédéric Galliano, Federica Govoni et al. "The mm-to-cm SED of spiral galaxies". EPJ Web of Conferences 257 (2022): 00005. http://dx.doi.org/10.1051/epjconf/202225700005.
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The mm-to-cm range of the Spectral Energy Distribution of spiral galaxies remains largely unexplored. Its coverage is required to disentangle the contribution of dust emission, free-free and synchrotron radiation and can provide constraints on dust models, star-formation rates and ISM properties. We present the case for a synergy between NIKA2 observations of nearby spirals and those from planned and current instrumentation at the Sardinia Radio Telescope, and report on a pilot K-band program to search for Anomalous Microwave Emission, an elusive emission component which is presumably related to dust.
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Lefèvre, Charlène, Laurent Pagani, Bilal Ladjelate, Michiel Min, Hiroyuki Hirashita y Robert Zylka. "Dust evolution in pre-stellar cores". EPJ Web of Conferences 228 (2020): 00013. http://dx.doi.org/10.1051/epjconf/202022800013.
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Dust grains are the building blocks of future planets. They evolve in size, shape and composition during the life cycle of the interstellar medium. We seek to understand the process which leads from diffuse medium grains to dust grains in the vicinity of protostars inside disks. As a first step, we propose to characterize the dust evolution inside pre-stellar cores thanks to multi-wavelength observations. We will present how NIKA2 maps are crucial to better constrain dust properties and we will introduce SIGMA: a new flexible dust model in open access.
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Romero, C., M. McWilliam, J. F. Macías-Pérez, R. Adam, P. Ade, P. André, H. Aussel et al. "A multi-instrument non-parametric reconstruction of the electron pressure profile in the galaxy cluster CLJ1226.9+3332". Astronomy & Astrophysics 612 (abril de 2018): A39. http://dx.doi.org/10.1051/0004-6361/201731599.
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Context. In the past decade, sensitive, resolved Sunyaev-Zel’dovich (SZ) studies of galaxy clusters have become common. Whereas many previous SZ studies have parameterized the pressure profiles of galaxy clusters, non-parametric reconstructions will provide insights into the thermodynamic state of the intracluster medium. Aim. We seek to recover the non-parametric pressure profiles of the high redshift (z = 0.89) galaxy cluster CLJ 1226.9+3332 as inferred from SZ data from the MUSTANG, NIKA, Bolocam, and Planck instruments, which all probe different angular scales. Methods. Our non-parametric algorithm makes use of logarithmic interpolation, which under the assumption of ellipsoidal symmetry is analytically integrable. For MUSTANG, NIKA, and Bolocam we derive a non-parametric pressure profile independently and find good agreement among the instruments. In particular, we find that the non-parametric profiles are consistent with a fitted generalized Navaro-Frenk-White (gNFW) profile. Given the ability of Planck to constrain the total signal, we include a prior on the integrated Compton Y parameter as determined by Planck. Results. For a given instrument, constraints on the pressure profile diminish rapidly beyond the field of view. The overlap in spatial scales probed by these four datasets is therefore critical in checking for consistency between instruments. By using multiple instruments, our analysis of CLJ 1226.9+3332 covers a large radial range, from the central regions to the cluster outskirts: 0.05 R500 < r < 1.1 R500. This is a wider range of spatial scales than is typically recovered by SZ instruments. Similar analyses will be possible with the new generation of SZ instruments such as NIKA2 and MUSTANG2.
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Poidevin, Frédérick. "Analysis of Galactic molecular cloud polarization maps: a review of the methods". EPJ Web of Conferences 228 (2020): 00019. http://dx.doi.org/10.1051/epjconf/202022800019.
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The Davis-Chandrasekhar-Fermi (DCF) method using the Angular Dispersion Function (ADF), the Histogram of Relative Orientations (HROs) and the Polarization-Intensity Gradient Relation (P-IGR) are the most common tools used to analyse maps of linearly polarized emission by thermal dust grains at submilliter wavelengths in molecular clouds and star-forming regions. A short review of these methods is given. The combination of these methods will provide valuable tools to shed light on the impact of the magnetic fields on the formation and evolution of subparsec scale hub-filaments that will be mapped with the NIKA2 camera and future experiments.
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Rigby, A. J., N. Peretto, R. Adam, P. Ade, M. Anderson, P. André, A. Andrianasolo et al. "GASTON: Galactic Star Formation with NIKA2 – evidence for the mass growth of star-forming clumps". Monthly Notices of the Royal Astronomical Society 502, n.º 3 (25 de enero de 2021): 4576–96. http://dx.doi.org/10.1093/mnras/stab200.
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ABSTRACT Determining the mechanism by which high-mass stars are formed is essential for our understanding of the energy budget and chemical evolution of galaxies. By using the New IRAM KIDs Array 2 (NIKA2) camera on the Institut de Radio Astronomie Millimétrique (IRAM) 30-m telescope, we have conducted high-sensitivity and large-scale mapping of a fraction of the Galactic plane (GP) in order to search for signatures of the transition between the high- and low-mass star-forming modes. Here, we present the first results from the Galactic Star Formation with NIKA2 (GASTON) project, a Large Programme at the IRAM 30-m telescope that is mapping ≈2 deg2 of the inner GP, centred on ℓ = 23${_{.}^{\circ}}$9, b = 0${_{.}^{\circ}}$05, as well as targets in Taurus and Ophiuchus in 1.15- and 2.00-mm continuum wavebands. In this paper, we present the first of the GASTON GP data taken, and present initial science results. We conduct an extraction of structures from the 1.15-mm maps using a dendrogram analysis and, by comparison to the compact source catalogues from Herschel survey data, we identify a population of 321 previously undetected clumps. Approximately 80 per cent of these new clumps are 70-μm-quiet, and may be considered as starless candidates. We find that this new population of clumps are less massive and cooler, on average, than clumps that have already been identified. Further, by classifying the full sample of clumps based upon their infrared-bright fraction – an indicator of evolutionary stage – we find evidence for clump mass growth, supporting models of clump-fed high-mass star formation.