83 research outputs found
Galaxyâgalaxy lensing in the outskirts of CLASH clusters: constraints on local shear and testing massâluminosity scaling relation
We present a selection of 24 candidate galaxyâgalaxy lensing (GGL) identified from Hubble images in the outskirts of the massive galaxy clusters from the Cluster Lensing And Supernova survey with Hubble (CLASH) . These GGLs provide insights into the mass distributions at larger scales than the strong-lensing region in the cluster cores. We built parametric mass models for three of these GGLs showing simple lensing configurations, in order to assess the properties of their lens and its environment. We show that the local shear estimated from the GGLs traces the gravitational potential of the clusters at a radial distance of 1â2 arcmin, allowing us to derive their velocity dispersion. We also find a good agreement between the strength of the shear measured at the GGL positions through strong-lensing modelling and the value derived independently from a weak-lensing analysis of the background sources. Overall, we show the advantages of using single GGL events in the outskirts of clusters to robustly constrain the local shear, even when only photometric redshift estimates are known for the source. We argue that the massâluminosity scaling relation of cluster members can be tested by modelling the GGLs found around them, and show that the mass parameters can vary up to âŒ30âperâcent between the cluster and GGL models assuming this scaling relation
A First Look at Spatially Resolved Balmer Decrements at from JWST NIRISS Slitless Spectroscopy
We present the first results on the spatial distribution of dust attenuation
at traced by the Balmer Decrement, H/H, in
emission-line galaxies using deep JWST NIRISS slitless spectroscopy from the
CAnadian NIRISS Unbiased Cluster Survey (CANUCS). H and H
emission line maps of emission-line galaxies are extracted and stacked in bins
of stellar mass for two grism redshift bins, and
. Surface brightness profiles for the Balmer Decrement are
measured and radial profiles of the dust attenuation towards H,
, are derived. In both redshift bins, the integrated
Balmer Decrement increases with stellar mass. Lower mass
(Log(/M)) galaxies have centrally
concentrated, negative dust attenuation profiles whereas higher mass galaxies
(Log(/M)) have flat dust attenuation
profiles. The total dust obscuration is mild, with on average and
mag in the low and high redshift bins respectively. We model the
typical light profiles of star-forming galaxies at these redshifts and stellar
masses with GALFIT and apply both uniform and radially varying dust attenuation
corrections based on our integrated Balmer Decrements and radial dust
attenuation profiles. If these galaxies were observed with typical JWST NIRSpec
slit spectroscopy ( shutters), on average,
H star formation rates (SFRs) measured after slit-loss corrections
assuming uniform dust attenuation will overestimate the total SFR by and at and
respectively.Comment: 7 pages, 5 figures, submitted to ApJ
CDM not dead yet: massive high-z Balmer break galaxies are less common than previously reported
Early JWST observations that targeted so-called double-break sources
(attributed to Lyman and Balmer breaks at ), reported a previously unknown
population of very massive, evolved high-redshift galaxies. This surprising
discovery led to a flurry of attempts to explain these objects' unexpected
existence including invoking alternatives to the standard CDM
cosmological paradigm. To test these early results, we adopted the same
double-break candidate galaxy selection criteria to search for such objects in
the JWST images of the CAnadian NIRISS Unbiased Cluster Survey (CANUCS), and
found a sample of 19 sources over five independent CANUCS fields that cover a
total effective area of arcmin at . However, (1) our SED
fits do not yield exceptionally high stellar masses for our candidates, while
(2) spectroscopy of five of the candidates shows that while all five are at
high redshifts, their red colours are due to high-EW emission lines in
star-forming galaxies rather than Balmer breaks in massive, evolved systems.
Additionally, (3) field-to-field variance leads to differences of
dex in the maximum stellar masses measured in the different fields, suggesting
that the early single-field JWST observations may have suffered from cosmic
variance and/or sample bias. Finally, (4) we show that the presence of even a
single massive outlier can dominate conclusions from small samples such as
those in early JWST observations. In conclusion, we find that the double-break
sources in CANUCS are not sufficiently massive or numerous to warrant
questioning the standard CDM paradigm.Comment: V2: correction of display problem of Fig.1 in Chrome browser.
Submitted to MNRAS, 10 pages (+4 in Appendix), 5 figures (+4), 1 table (+1
The Sparkler: Evolved High-Redshift Globular Clusters Captured by JWST
Using data from JWST, we analyze the compact sources ("sparkles") located
around a remarkable galaxy (the "Sparkler") that is
strongly gravitationally lensed by the galaxy cluster SMACS
J0723.3-7327. Several of these compact sources can be cross-identified in
multiple images, making it clear that they are associated with the host galaxy.
Combining data from JWST's {\em Near-Infrared Camera} (NIRCam) with archival
data from the {\em Hubble Space Telescope} (HST), we perform 0.4-4.4m
photometry on these objects, finding several of them to be very red and
consistent with the colors of quenched, old stellar systems. Morphological fits
confirm that these red sources are spatially unresolved even in strongly
magnified JWST/NIRCam images, while JWST/NIRISS spectra show [OIII]5007
emission in the body of the Sparkler but no indication of star formation in the
red compact sparkles. The most natural interpretation of these compact red
companions to the Sparkler is that they are evolved globular clusters seen at
. Applying \textsc{Dense Basis} SED-fitting to the sample, we infer
formation redshifts of for these globular cluster
candidates, corresponding to ages of Gyr at the epoch of
observation and a formation time just 0.5~Gyr after the Big Bang. If
confirmed with additional spectroscopy, these red, compact "sparkles" represent
the first evolved globular clusters found at high redshift, could be amongst
the earliest observed objects to have quenched their star formation in the
Universe, and may open a new window into understanding globular cluster
formation. Data and code to reproduce our results will be made available at
\faGithub\href{https://niriss.github.io/sparkler.html}{http://canucs-jwst.com/sparkler.html}.Comment: Submitted to ApJL. Comments are welcome. Data and code to reproduce
our results will be made available at niriss.github.io/sparkler.htm
The first large catalogue of spectroscopic redshifts in Webb's First Deep Field, SMACS J0723.37327
We present a spectroscopic redshift catalogue of the SMACS J0723.37327
field ("Webb's First Deep Field") obtained from JWST/NIRISS grism spectroscopy
and supplemented with JWST/NIRSpec and VLT/MUSE redshifts. The catalogue
contains a total of 190 sources with secure spectroscopic redshifts, including
156 NIRISS grism redshifts, 123 of which are for sources whose redshifts were
previously unknown. These new grism redshifts are secured with two or more
spectroscopic features (64 sources), or with a single spectral feature whose
identity is secured from the object's nine-band photometric redshift (59
sources). These are complemented with 17 NIRSpec and 48 MUSE redshifts,
including six new NIRSpec redshifts identified in this work. In addition to the
cluster galaxy redshifts (for which we provide 40 new
NIRISS absorption-line redshifts), we also find three prominent galaxy
overdensities at higher redshifts - at , , and - that
were until now not seen in the JWST/NIRSpec and VLT/MUSE data. The paper
describes the characteristics of our spectroscopic redshift sample and the
methodology we have employed to obtain it. Our redshift catalogue is made
available to the community at https://niriss.github.io/smacs0723.Comment: 19 pages, 13 figures, 3 appendices. Accepted for publication in MNRA
Grid'5000: a large scale and highly reconfigurable grid experimental testbed
Large scale distributed systems such as Grids are difficult to study from theoretical models and simulators only. Most Grids deployed at large scale are production plat-forms that are inappropriate research tools because of their limited reconfiguration, control and monitoring capa-bilities. In this paper, we present Gridâ5000, a 5000 CPU nation-wide infrastructure for research in Grid computing. Gridâ5000 is designed to provide a scientific tool for com-puter scientists similar to the large-scale instruments used by physicists, astronomers, and biologists. We describe the motivations, design considerations, architec-ture, control, and monitoring infrastructure of this experi-mental platform. We present configuration examples and performance results for the reconfiguration subsystem
The endocannabinoid system controls food intake via olfactory processes
Comment in Sensory systems: the hungry sense. [Nat Rev Neurosci. 2014] Inhaling: endocannabinoids and food intake. [Nat Neurosci. 2014]; International audience; Hunger arouses sensory perception, eventually leading to an increase in food intake, but the underlying mechanisms remain poorly understood. We found that cannabinoid type-1 (CB1) receptors promote food intake in fasted mice by increasing odor detection. CB1 receptors were abundantly expressed on axon terminals of centrifugal cortical glutamatergic neurons that project to inhibitory granule cells of the main olfactory bulb (MOB). Local pharmacological and genetic manipulations revealed that endocannabinoids and exogenous cannabinoids increased odor detection and food intake in fasted mice by decreasing excitatory drive from olfactory cortex areas to the MOB. Consistently, cannabinoid agonists dampened in vivo optogenetically stimulated excitatory transmission in the same circuit. Our data indicate that cortical feedback projections to the MOB crucially regulate food intake via CB1 receptor signaling, linking the feeling of hunger to stronger odor processing. Thus, CB1 receptor-dependent control of cortical feedback projections in olfactory circuits couples internal states to perception and behavior
Photometric redshift estimations in large multi-wavelength surveys and application to galaxy cluster property studies
The redshift is an observable quantity which is linked to both the distances that separate us from extragalactic sources and to the Universeâs cosmology. To constrain the nature of the dark universe (i.e., dark energy and dark matter) large cosmological surveys, such as the Euclid survey, require measuring redshifts for billions of galaxies. Such kind of mission must rely on photometric redshifts, which in return must have the best precision and accuracy possible. I this thesis, I worked on the validation and the improvements of the photometric redshift measurement methods planned for Euclid mission. I also explored novel methods to extract the photometry in large survey images, and to combine the data of different surveys in a configuration close to the expected Euclid one. Moreover, I investigated the possibility to use such kind of data to study the evolution of galaxies in dense environments
Blaise Pascal, Pensées de M. Pascal sur la religion et sur quelques autres sujets, qui ont esté trouvées aprés sa mort parmy ses papiers
Munie dâun achevĂ© dâimprimer datĂ© du 2 janvier 1670, lâĂ©dition originale des PensĂ©es commença dâĂȘtre diffusĂ©e une quinzaine de jours plus tard environ : le 21 janvier 1670, Gilbert de Choiseul du Plessis-Praslin, Ă©vĂȘque de Comminges, lâun des prĂ©lats auxquels le livre avait Ă©tĂ© soumis pour approbation en 1669, Ă©crivait Ă Florin PĂ©rier pour accuser rĂ©ception du livre et remercier les Ă©diteurs dâavoir pris en compte les « changements qui [lui avaient] paru nĂ©cessaires ». Lâexemplaire ici prĂ©sentĂ© est reliĂ© aux armes de Pierre-Daniel Huet (1630-1721) et est rendu trĂšs prĂ©cieux par les notes de lecture quâil y a laissĂ©es : Ă©minent savant de lâEurope de son temps, dotĂ© dâune trĂšs vaste culture littĂ©raire, historique et philosophique, Huet a marquĂ© les passages qui lâont le plus retenu par de nombreux soulignements dans le texte ou Ă sa marge, et dĂ©veloppĂ© aussi sa pensĂ©e dans des notes qui vont de brefs renvois bibliographiques Ă dâautres lectures jusquâĂ des remarques critiques longues de plusieurs lignes. Au-delĂ des faits historiques quâil oppose ponctuellement Ă Pascal en puisant Ă son immense Ă©rudition, Huet, allant droit au cĆur du projet apologĂ©tique des PensĂ©es , sâintĂ©resse surtout au mode dâaffirmation propre Ă la foi chrĂ©tienne : de lĂ lâattention quâil prĂȘte aux passages relatifs aux prophĂ©ties bibliques comme preuves scripturaires et Ă la question gĂ©nĂ©rale des rapports de la foi et de la raison. Sa lecture exprime un point de vue fidĂ©iste trĂšs affirmĂ© : Huet relĂšve chez Pascal toutes les formules dâhumiliation de la raison qui soulignent lâimpuissance de celle-ci Ă Ă©tablir une vĂ©ritĂ© en matiĂšre de foi. La conviction dâune disjonction radicale de la foi et de la raison lâamĂšne aussi Ă instruire une critique de lâargument du pari, dans lequel il dĂ©cĂšle un reste de rationalisme : lâargumentation pascalienne soumet Ă juste titre la raison Ă la foi, mais elle « suppose que cette soumission mĂȘme doit dĂ©pendre de la raison ; et il me semble au contraire que de soumettre la raison Ă la foi, est plutĂŽt lâouvrage de la foi que de la raison », note-t-il p. 48, face Ă lâun des fragments de la liasse « Soumission et usage de la raison » (S. 205). Pour Huet, toute affirmation de lâexistence de Dieu dans laquelle la raison aurait quelque part, fĂ»t-elle rĂ©duite Ă parier faute de pouvoir dĂ©montrer, revient Ă nier son absolue transcendance. Huet a inscrit la date du 23 fĂ©vrier 1670 Ă la fin du volume. Elle se rapporte Ă lâacquisition du livre et non Ă sa lecture, qui, par lâunitĂ© dâĂ©criture de lâannotation, paraĂźt avoir Ă©tĂ© faite dâune traite et non par Ă©tapes successives. Or on relĂšve parmi les notes une rĂ©fĂ©rence au second tome de la Recherche de la vĂ©ritĂ© de Malebranche, paru en 1675. Aussi la lecture de Huet est-elle sans doute contemporaine de la prĂ©paration de sa Demonstratio evangelica (1679), ouvrage qui partage avec les PensĂ©es un mĂȘme dessein dâapologie du christianisme mais, sâappuyant sur une histoire comparĂ©e des religions, le conduit selon des voies trĂšs diffĂ©rentes.tĂ©lĂ©chargeabl
Biblia. A.T. NĂșmeros. FrancĂ©s
Copia digital. Valladolid : Junta de Castilla y LeĂłn. ConsejerĂa de Cultura y Turismo, 2012-2013Sign.: ĂŁ8, ĂȘ1, A-Z8, 2A-2F8, 2G
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