Accueil > Contribution List

Liste des présentations

Affichage55 contributions sur 55
A tremendous international effort is currently dedicated to observing the so-called primordial $B$ modes of the Cosmic Microwave Background (CMB) polarisation. If measured, this faint signal imprinted by the primordial gravitational wave background, would be an evidence of the inflation epoch and quantify its energy scale, providing a rigorous test of fundamental physics far beyond the reach of ac ... Plus
Présenté par Mr. Jonathan AUMONT on 5 juin 2019 à 16:25
Galactic molecular clouds are made of subparsec scale filamentary structures in which star formation occurs. The role of the magnetic fields in the formation and evolution of such structures leading to the formation of prestellar cores is still poorly understood, one reason being the lack of resolution provided by current and previous experiments. By measuring the linear polarized emission of the ... Plus
Présenté par Frédérick POIDEVIN on 5 juin 2019 à 16:55
The inflationary scenario generically predicts the existence of primordial gravitational waves (GW) over a wide range of amplitudes from slow-roll to multi-field models. Currently the most promising method for constraining, and potentially detecting an inflationary GW background is to search for the imprint of these tensor perturbations in the cosmic microwave background (CMB) B-mode polarization. ... Plus
Présenté par Dr. Denis BARKATS on 6 juin 2019 à 16:00
We are developing a 100GHz band camera designed for survey of distant galaxies. Field-of-view of this camera is around 3-arcmin, and 100GHz band observation helps peer through the characteristics of very distant galaxies. This is also a prototype for the future 10m Antarctic telescope to survey southern distant galaxies. The focal plane array of this camera is 109 pixel antenna-coupled Microwave K ... Plus
Présenté par Mr. Pranshu MANDAL on 5 juin 2019 à 10:00
Session: SZ and X-rays
The abundance of galaxy clusters, per unit of mass and redshift, is a very powerful tool in order to constrain cosmological parameters as the matter density Ωm, and the amplitude of the primordial fluctuation σ8. However, the cluster mass is not an observable. The multicomponent nature of galaxy clusters helps to bypass this problem. In fact, from the observation of each different cluster compon ... Plus
Présenté par Mr. Antonio FERRAGAMO on 4 juin 2019 à 17:00
Session: SZ observations
The NIKA2 SZ large program (LPSZ) was designed to take advantage of the NIKA2 high angular resolution and large eld of view to help us improve our knowledge of galaxy clusters. It consists in observing ∼50 clusters from intermediate to high red- shift (z ∈ [0.5, 0.9]) to re-compute the relations needed for cluster-based cosmological analysis, i.e. the mean pressure pro le of the intra-cluster ... Plus
Présenté par Mr. Florian KÉRUZORÉ on 4 juin 2019 à 11:30
The performance of the NIKA2 camera at the IRAM 30-m telescope have been assessed using a reference data set including observations acquired between January 2017 and February 2018. This data set consists of a large amount of observations of primary and secondary calibrators and faint sources, which span the whole range of observing elevations and atmospheric conditions encountered at the IRAM 30-m ... Plus
Présenté par Dr. Laurence PEROTTO on 3 juin 2019 à 14:20
Session: SZ observations
Upcoming optical/IR surveys will have both the sensitivity and the area to push cluster detection to $z > 2$. The SZ and X-ray follow-ups of richness-selected clusters enable investigating the ICM properties at high redshift and improve our understanding of cluster formation. With both a wide field of view and a high angular resolution, NIKA2 is a very well suited instrument to map the SZ signal o ... Plus
Présenté par Dr. Florian RUPPIN on 4 juin 2019 à 11:00
Session: SZ observations
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 the mass-observabl ... Plus
Présenté par Prof. Frédéric MAYET on 4 juin 2019 à 10:00
The NIKA2 Sunyaev-Zel'dovich Large Program (LPSZ) 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. Clusters science implementation to Cosmology can be biased due to inaccurate knowledge of IntraCluster Medium (ICM) pressure profiles in shape, scatter and redshift evolution. Hydrodynamical N-body s ... Plus
Présenté par Prof. Marco DE PETRIS on 6 juin 2019 à 09:30
The Planck mission has brought considerable constraints on the properties of dust, and their evolution from the most diffuse, high-latitude, Galactic ISM to the densest regions of the Gould Belt (Planck 2013 results. XI, Planck Int. Results 2015, XXIX). The combined analysis of ancillary and Planck HFI data has imposed a revision of dust models for the diffuse/translucent ISM, both in total and po ... Plus
Présenté par Dr. Vincent GUILLET on 5 juin 2019 à 11:30
In this talk we review the formalism for the modelling of the Sunyaev Zeldovich (SZ) power spectrum and cluster counts and how to compare them with observations. We outline their dependencies on cosmological parameters, as well as the mass bias associated with the X-ray calibration of the cluster masses. We outline the role played by the pressure profile of the intra cluster medium, for which N ... Plus
Présenté par Dr. Boris BOLLIET on 6 juin 2019 à 10:30
Planets and planetesimals are formed in the gas- and dust-rich protoplanetary disks surrounding nascent stars in the first 10 Myr of their life. Planetesimals belts, or debris disks, that remain afterward are unique objets to study planetary systems that have evolved from these primordial structures. On one hand, optical/IR observations reveal small sized grains that are partly blown out the syst ... Plus
Présenté par Dr. Jean-François LESTRADE on 6 juin 2019 à 14:00
Session: Friday session
Dust is the only tracer that is present from the edge of the interstellar cloud to the densest part, inside which stars and planets will form, named pre-stellar cores. It allows to trace the density structure of the cloud, of the core(s), and of the subsequent protoplanetary disk where it becomes a major actor of the planet formation. Dust grains evolve from bare simple elongated shape in the diff ... Plus
Présenté par Dr. Charlène LEFEVRE on 7 juin 2019 à 12:00
Session: SZ and X-rays
We present the dynamical properties and the individual spatially resolved radial mass profiles of a sample of 77 massive clusters in the [0.05-1] redshift range detected via the Sunyaev-Zel'dovich effect. For the 5 clusters at z>0.9, we present a method to study such objects that optimally exploits information from XMM-Newton and Chandra observations. The combination of Chandra’s excellent spa ... Plus
Présenté par Dr. Iacopo BARTALUCCI on 4 juin 2019 à 16:00
Session: SZ and X-rays
The Sunyaev-Zeldovich effect provides an observational window to the intracluster medium complementary to X-ray observations, and over the last few years has proved to be a mature technique to efficiently detect and characterize galaxy clusters. For instance, the Planck survey has mapped the whole microwave sky, detecting almost 2000 candidate massive clusters up to z~1, performing the first all-s ... Plus
Présenté par Dr. Mariachiara ROSSETTI on 4 juin 2019 à 16:30
Session: SZ observations
Complementarily to X-ray observations, the thermal SZ effect is a powerful tool to probe the baryonic content of galaxy clusters from their core to their peripheries. While contaminations by astrophysical (Galactic and extragalactic thermal dust) and insrumental backgrounds require us to scan the thermal SZ signal across various frequencies, the multi-scale nature of cluster morphologies require u ... Plus
Présenté par Mr. Herve BOURDIN on 4 juin 2019 à 11:55
Session: Friday session
We will present the latest results of a 69 arcmin2 ALMA survey at 1.1mm, GOODS-ALMA, matching the deepest HST-WFC3 H-band observed region of the GOODS-South field. We have extracted two catalogs, one of galaxies purely selected by ALMA, from which we have identified sources both with and without HST counterparts, and another catalog based on priors. Our wide contiguous survey allows us to push the ... Plus
Présenté par Mr. Maximilien FRANCO on 7 juin 2019 à 10:00
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 i ... Plus
Présenté par Ricardo RIZZO on 6 juin 2019 à 15:00
Session: Friday session
Over the last decade, Herschel observations of the Galactic interstellar medium have transformed our understanding of the early stages of star formation. At the low-mass end of the stellar initial mass function (IMF), a paradigm has emerged in which low-mass cores – the progenitors of stars with masses from ~0.1 to a couple of solar masses – are thought to form as the result of gravitational i ... Plus
Présenté par Dr. Nicolas PERETTO on 7 juin 2019 à 11:00
Star formation is a key process in astrophysics. At large scale, it regulates the energy budget of galaxies (especially massive stars) while at a small scale it sets the initial conditions for planet formation. It has been shown that the formation of stars, and the nature of the stars that will be formed, is very sensitive to the physical conditions at the cloud scale. Hence, star formation is a m ... Plus
Présenté par Frédérique MOTTE on 5 juin 2019 à 17:25
Most recent studies show that the tension observed between the cosmological constraints based on cluster abundance from SZ catalogs and from CMB primary anisotropies can be cancelled by a variation of the hydrostatic bias parameter. However, the value of the hydrostatic bias needed in order to alleviate this tension is in strong disagreement with the current estimates of this parameter based on le ... Plus
Présenté par Dr. Florian RUPPIN on 6 juin 2019 à 10:00
Observations of the polarised dust emission with Planck and the future SPICA at large scale and with ALMA, SCUBA2 and NIKA2 at smaller scales trace the interaction between the magnetic field and the denser part of the ISM as molecular clouds and star formation regions. However, a clear interpretation of the Stokes parameters Q and U, and of the associated polarisation vector P, is difficult. The c ... Plus
Présenté par Dr. Jean-François ROBITAILLE on 5 juin 2019 à 14:55
Session: Introduction
Introducing mm Universe @ NIKA2
Présenté par Prof. Frédéric MAYET on 3 juin 2019 à 13:30
Mapping millimetre continuum emission of the astronomical sky has become a key issue in modern multi-wavelength astrophysics as such mapping is required to tackle a series of very important questions related to cosmology, galaxy evolution, formation of individual and clustered starts and finally the nature of circumstellar envelops and disks. In particular the spectro-imaging at low resolution fr ... Plus
Présenté par Mr. Alessandro FASANO on 6 juin 2019 à 16:30
CONCERTO is a new instrument planned to be installed in the APEX Cassegrain Cabin in early 2021. It is a spectrometer with an instantaneous field of view exceeding 300 Sq. arcmin. and a spectral resolution of 1.5 GHz. It covers the frequency band 120-360 GHz. The main scientific aim of CONCERTO is to map in three dimensions the fluctuations of the CII line intensity in the reionisation and post-re ... Plus
Présenté par Prof. Guilaine LAGACHE on 6 juin 2019 à 17:00
Herschel imaging surveys of Galactic molecular clouds have emphasized the quasi-universality of the filamentary structure of the cold ISM and the key role of filaments in the star formation process. Planck polarization data moreover suggest that the formation and evolution of star-forming filaments is at least partly controlled by magnetic fields. I will summarize the main objectives and pr ... Plus
Présenté par Dr. Philippe ANDRÉ on 5 juin 2019 à 13:30
Mapping the structure of interstellar magnetic fields in the cold gas of nearby galaxies is crucial to understand how magnetic fields influence gas dynamics in galaxies, and in particular the role of the field in regulating star formation, driving galactic outflows, and fuelling galactic nuclei. In this contribution, I will present our group's ongoing efforts to map the magnetic field structure i ... Plus
Présenté par Dr. Annie HUGHES
The NIKA2 instrument, operating at the IRAM 30-meters telescope, is based on the LEKID array technology dedicated to millimeter wave astronomy. This instrument is composed of one low frequency array for the 120-180GHz range, and two high frequency polarization sensitive arrays for the 220-280GHz range. Since 2013 different versions of the arrays have been developed for NIKA2. We will describe the ... Plus
Présenté par Dr. Johannes GOUPY on 5 juin 2019 à 09:00
Session: Friday session
The steps taken to tailor to NIKA2 observations the Scanamorphos algorithm (initially developed to subtract low-frequency noise from Herschel on-the-fly observations) will be 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 g ... Plus
Présenté par Helene ROUSSEL on 7 juin 2019 à 09:00
NIKA2 has been permanently installed at the IRAM Pico Veleta 30m telescope since October 2015. After the first commissioning campaigns, NIKA2 is now open to the international community and has been used in many scientific observing pools. Although invisible to the final user, the complexity of the instrument requires a lot of careful work to get everything ready before each pool, starting from the ... Plus
Présenté par Martino CALVO on 3 juin 2019 à 16:20
I will describe in general the NIKA2 instrument. I will then focus on some possible points for improvements. For example: new dichroic, new 1mm arrays (developed at Néel), 1GHz electronics (LPSC), potential telescope upgrade (IRAM).
Présenté par Alessandro MONFARDINI on 3 juin 2019 à 13:50
I will introduce NOEMA interferometer, its latest upgrades and capabilities. In particular, I will detail the increase of sensitivity with more antennas, increase of spatial resolution with track extension, and increase of bandwidth with new receiver generation as well as future dual band upgrade. Finally, I will discuss the complementarity between NOEMA and NIKA2 and possible synergies from galac ... Plus
Présenté par Dr. Charlène LEFEVRE on 5 juin 2019 à 11:00
With its large FOV and high sensitivity, NIKA2 is a high mapping speed instrument, uniquely suited for deep surveys. During commissioning, we had the opportunity to observe faint and moderately faint sources with NIKA2. This talk will summarize the latest developments on the NIKA2 data reduction pipeline and show its first application to small deep fields and source counting.
Présenté par Dr. Nicolas PONTHIEU on 3 juin 2019 à 14:50
Most of the people attending the conference have already an experience with NIKA2 observations and some of its subtleties. The NIKA2 observing sessions are organized in pools, a shared risk way of scheduling projects according to their priorities, and weather and stability requests, in order to ensure that everyone gets the best of their data. As NIKA2 reaches its second year of science operatio ... Plus
Présenté par Dr. Bilal LADJELATE on 3 juin 2019 à 15:50
NIKA2 is equipped with a polarization system composed by a multi-mesh half wave plate (HWP) and a polarizer placed at the cryostat stage of 100 mK which transmits and re ects the two orientation of the linear polarization on two 1mm KID-arrays. The polarizer is needed because the NIKA2 detectors KIDs are unsensitive to the polarization, the warm HWP placed in front of the cryostat window modulate ... Plus
Présenté par Dr. Alessia RITACCO on 5 juin 2019 à 14:00
Session: SZ and X-rays
High-resolution spectral imaging observations of the SZ effects promise to provide a vastly broaden view of structure and evolution of galaxy clusters, by enabling unique measurements of thermodynamic and kinematic properties of the cluster gas via thermal and kinematic SZ effects. One of the new frontiers includes the exploration of the extremely low-density regions in the outskirts of galaxy clu ... Plus
Présenté par Prof. Daisuke NAGAI on 4 juin 2019 à 17:30
Session: SZ observations
Clusters of galaxies are unique cosmological probes sensitive to the primordial density fluctuations, and the expansion history and energy content of the Universe. The thermal Sunyaev-Zeldovich (tSZ) effect is an observable of choice for cluster cosmology due to the low scatter in the relationship between SZ flux and cluster mass, and the construction of large tSZ selected cluster catalogs. The Pl ... Plus
Présenté par Dr. Juan Francisco MACIAS-PEREZ on 4 juin 2019 à 09:30
Highlighting 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 polarimetric imaging of nearby clouds will help us to start clarifying the geometry of the B field within dense cores and mole ... Plus
Présenté par Mr. Hamza AJEDDIG on 5 juin 2019 à 14:30
Saturn’s icy satellites, which are in synchronous rotation around Saturn, often present a different albedo on their leading and trailing sides, which interact differently with Saturn’s dusty rings. Because longer wavelengths probe deeper into the subsurface, observing both sides at a variety of wavelengths indicates possible changes in thermal and physical properties with depth. The Cassini mi ... Plus
Présenté par Ms. Lea BONNEFOY on 6 juin 2019 à 14:30
The NIKA2 team are continuously working on improving the performance of the NIKA2 arrays. In this talk, we present our recent developments on the 1mm array from three aspects. Firstly, a small pixel design has been studied to achieve higher angular resolution. Secondly, a thorough simulation and FTS measurements have been performed to understand the frequency response. Thirdly, a capacitor trimmin ... Plus
Présenté par Mr. Shibo SHU on 5 juin 2019 à 09:30
Session: SZ and X-rays
TBD
Présenté par Mr. Juan Francisco MACIAS-PEREZ on 4 juin 2019 à 15:00
Session: Friday session
From molecular clouds to young stellar objects, every step in the evolution of young stars can be observed in the millimetric range. As part of the NIKA2 (Adam et al. 2018) Large Program GASTON (PI: Nicolas Peretto), we observed at 1.2mm and 2mm the Ophiuchus Molecular Cloud. The dual band capabilities of NIKA2 allow us to understand the properties of dust in star-forming regions, and their rela ... Plus
Présenté par Dr. Bilal LADJELATE on 7 juin 2019 à 11:30
Session: SZ and X-rays
The imaging of galaxy clusters through the Sunyaev-Zel'dovich effect is a valuable tool to probe the thermal pressure of the intra-cluster gas especially in the outermost regions, where X-ray observations suffer from photon statistics. For the first time, we produce maps of the Comptonization parameter by applying a locally parametric algorithm for sparse component separation to the latest *P ... Plus
Présenté par Anna Silvia BALDI on 4 juin 2019 à 14:30
Session: Friday session
More than half of the photons emitted by stars across cosmic times have been absorbed by cosmic dust and re-emitted in the far-infrared and millimeter wavelength domain. Herschel and ALMA revealed that very massive and very dusty galaxies already exist in the early Universe (up to z~7). These objects are one of the keys to understand the formation of the most massive galaxies. However, these objec ... Plus
Présenté par Alexandre BEELEN on 7 juin 2019 à 09:30
Galaxy clusters are the most massive gravitationally collapsed objects in the Universe. They are also the most rare objects and, therefore, large computational volumes have to be simulated if one wants to obtain a statistical significant sample of such objects that can be used to calibrate the global scaling relations, or to understand the possible mass biases due to inaccuracies of the classica ... Plus
Présenté par Prof. Gustavo YEPES on 6 juin 2019 à 09:00
NIKA, the NIKA2 path nder, was equipped of a room temperature polarization system (a half wave plate and a grid polarizer facing the cryostat window). This polarization system was the test bench for the NIKA2 polarimeter and was used during few observational/technical campaigns between 2014 and 2015. In particular during the last observing week of NIKA at the IRAM 30m telescope, in February 2015, ... Plus
Présenté par Dr. Alessia RITACCO on 5 juin 2019 à 15:55
Session: SZ observations
I will review the evolution of observations of the Sunyaev-Zeldovich (SZ) signal from groups and clusters of galaxies within the course of the past two decades. The SZ effect has become an efficient way to investigate the astrophysics of the hot intra-cluster gas, very competitive and complementary to X-ray observations, and thereby renew the use of massive halos as a cosmological probe. I will di ... Plus
Présenté par Dr. Etienne POINTECOUTEAU on 4 juin 2019 à 09:00
Session: SZ and X-rays
X-ray and Sunyaev-Zeldovich observations provide independent and complementary ways of determining the properties of the intracluster medium (ICM). Joint reconstructions of galaxy cluster properties combining X-ray and SZ data are clearly superior to similar analyzes based on one observable only, since the two methods have a different radial dependency and probe different thermodynamic quantities. ... Plus
Présenté par Dr. Dominique ECKERT on 4 juin 2019 à 14:00
Pulsars are fascinating astrophysical objects that enable a variety of experiments usually with unrivalled precision. For example, pulsars have been used to test the equation-of-state of ultra-dense matter, or General Relativity up to the highest precision to date. However, although we have been very successful using pulsars as astronomical tools, we still do not fully understand their radio emiss ... Plus
Présenté par Dr. PABLO TORNE on 3 juin 2019 à 16:50
Session: SZ and X-rays
The total mass of a galaxy cluster is one of its most fundamental properties. Together with the redshift, the mass links observation and theory, allowing us to use the cluster population to test models of structure formation and to constrain cosmological parameters. I summarise the state of the art in cluster mass estimation methods, with particular emphasis on SZ measurements and their combinatio ... Plus
Présenté par Dr. Gabriel PRATT
The relationship between supermassive black hole (SMBH) accretion and star formation has lead to controversial studies claiming that Active Galactic Nuclei (AGN) activity might both quench and enhance galaxies' star-forming content. Especially at high redshift (z>2), their interplay is still poorly understood, also due to the lack of accurate estimates of star formation rate (SFR) and AGN power in ... Plus
Présenté par Ivan DELVECCHIO on 5 juin 2019 à 12:00
Galaxy cluster analyses at different wavelengths allows a better understanding of their formation and evolution, leading to a more realistic modeling of their physics. Comparing optical, X-ray and SZ cluster samples also enables us to check the selection functions of the surveys, and to test the cosmological representativeness of the detections. As a consequence, the multi-wavelength approach is a ... Plus
Présenté par Dr. Marina RICCI on 6 juin 2019 à 17:30
Our Universe is filled by cosmic microwave background radiation (CMB) which is extremely isotropic and has excellent black body spectrum with temperature 2.7 Kelvin and no spectral deviations from black body are detected in the CMB monopole till now. But 50 years ago it was recognised that "shadows" in the angular distribution of CMB in the directions where clouds of very hot T_e~10^6-10^ ... Plus
Présenté par Prof. Rashid SUNYAEV on 6 juin 2019 à 11:30
Session: SZ and X-rays
Galaxy clusters are dark-matter dominated systems enclosed in a volume that is a high-density microcosm of the rest of the universe. What is their true mass scale? What are the statistical properties of the representative population? How does their detectability depend on baryon physics? We have learned a lot on these fundamental questions with our current projects, like XMM-Newton Cluster Outsk ... Plus
Présenté par Dr. Stefano ETTORI on 4 juin 2019 à 13:30