96 research outputs found
<i>AKARI</i>/IRC source catalogues and source counts for the IRAC Dark Field, ELAIS North and the <i>AKARI</i> Deep Field South
We present the first detailed analysis of three extragalactic fields (IRAC Dark Field, ELAIS-N1, ADF-S) observed by the infrared satellite, AKARI, using an optimized data analysis toolkit specifically for the processing of extragalactic point sources. The InfaRed Camera (IRC) on AKARI complements the SpitzerSpace Telescope via its comprehensive coverage between 8–24 μm filling the gap between the Spitzer/IRAC and MIPS instruments. Source counts in the AKARI bands at 3.2, 4.1, 7, 11, 15 and 18 μm are presented. At near-infrared wavelengths, our source counts are consistent with counts made in other AKARI fields and in general with SpitzerIRAC (except at 3.2 μm where our counts lie above). In the mid-infrared (11 – 18 μm), we find our counts are consistent with both previous surveys by AKARI and the Spitzer peak-up imaging survey with the InfraRed Spectrograph (IRS). Using our counts to constrain contemporary evolutionary models, we find that although the models and counts are in agreement at mid-infrared wavelengths there are inconsistencies at wavelengths shortward of 7 μm, suggesting either a problem with stellar subtraction or indicating the need for refinement of the stellar population models. We have also investigated the AKARI/IRC filters, and find an active galactic nucleus selection criteria out to z AKARI 4.1, 11, 15 and 18 μm colours
Environments of a sample of AzTEC submillimetre galaxies in the COSMOS field
Aims. Submillimetre galaxies (SMGs) are bright sources at submillimetre wavelengths (F-850 mu m>2-5 mJy). Made up of mostly of high-z galaxies (z>1), SMGs are amongst the most luminous dusty galaxies in the Universe. These galaxies are thought to be the progenitors of the massive elliptical galaxies in the local Universe and to reside in massive haloes at early epochs. Studying their environments and clustering strength is thus important to put these galaxies in a cosmological context.Methods. We present an environmental study of a sample of 116 SMGs in 96 ALMA observation fields, which were initially discovered with the AzTEC camera on ASTE and identified with high-resolution 1.25 mm ALMA imaging within the COSMOS survey field, having either spectroscopic or unambiguous photometric redshift. We analysed their environments making use of the latest release of the COSMOS photometric catalogue, COSMOS2015, a catalogue that contains precise photometric redshifts for more than half a million objects over the 2 deg(2) COSMOS field. We searched for dense galaxy environments computing the so-called overdensity parameter as a function of distance within a radius of 5 from the SMG. We validated this approach spectroscopically for those SMGs for which spectroscopic redshift is available. As an additional test, we searched for extended X-ray emission as a proxy for the hot intracluster medium, performing an X-ray stacking analysis in the 0.5-2 keV band with a 32 '' aperture and our SMG position using all available XMM-Newton and Chandra X-ray observations of the COSMOS field.Results. We find that 27% (31 out of 116) of the SMGs in our sample are located in a galactic dense environment; a fraction that is similar to previous studies. The spectroscopic redshift is known for 15 of these 31 sources, thus this photometric approach is tested using spectroscopy. We are able to confirm that 7 out of 15 SMGs lie in high-density peaks. However, the search for associated extended X-ray emission via an X-ray stacking analysis leads to a detection that is not statistically significant.Peer reviewe
First look with JWST spectroscopy: galaxies resemble local analogues
Deep images and near-IR spectra of galaxies in the field of the lensing
cluster SMACS J0723.3-7327 were recently taken in the Early Release
Observations program of JWST. Among these, two NIRSpec spectra of galaxies at
and one at were obtained, revealing for the first time
rest-frame optical emission line spectra of galaxies in the epoch of
reionization, including the detection of the important[OIII]4363 auroral line
(see JWST PR 2022-035). We present an analysis of the emission line properties
of these galaxies, finding that these galaxies have a high excitation (as
indicated by high ratios of [OIII]/[OII], [NeIII]/[OII]), strong
[OIII]4363/H, high equivalent widths, and other properties which are
typical of low-metallicity star-forming galaxies. Using the direct method we
determine oxygen abundances of in two galaxies, and
a lower metallicity of in the galaxy
using different strong line methods. More accurate metallicity determinations
will require better data. With stellar masses estimated from SED fits, we find
that the three galaxies lie close to or below the mass-metallicity
relation. Overall, these first galaxy spectra at show a strong
resemblance of the emission lines properties of galaxies in the epoch of
reionization with those of relatively rare local analogues previously studied
from the SDSS. Clearly, the first JWST observations demonstrate already the
incredible power of spectroscopy to reveal properties of galaxies in the early
Universe.Comment: 6 pages, 6 Figures. Accepted for publication in Astronomy &
Astrophysics Letter
The ALMA REBELS Survey: The First Infrared Luminosity Function Measurement at $\mathbf{z \sim 7}
We present the first observational infrared luminosity function (IRLF)
measurement in the Epoch of Reionization (EoR) based on a UV-selected galaxy
sample with ALMA spectroscopic observations. Our analysis is based on the ALMA
large program Reionization Era Bright Emission Line Survey (REBELS), which
targets 42 galaxies at with [CII] 158\micron line scans.
16 sources exhibit a dust detection, 15 of which are also spectroscopically
confirmed through the [CII] line. The IR luminosities of the sample range from
to 12.2. Using the UVLF as a proxy to derive the
effective volume for each of our target sources, we derive IRLF estimates, both
for detections and for the full sample including IR luminosity upper limits.
The resulting IRLFs are well reproduced by a Schechter function with the
characteristic luminosity of . Our
observational results are in broad agreement with the average of predicted
IRLFs from simulations at . Conversely, our IRLFs lie significantly
below lower redshift estimates, suggesting a rapid evolution from to
, into the reionization epoch. The inferred obscured contribution to
the cosmic star-formation rate density at amounts to
which is at
least 10\% of UV-based estimates. We conclude that the presence of dust
is already abundant in the EoR and discuss the possibility of unveiling larger
samples of dusty galaxies with future ALMA and JWST observations.Comment: 9 pages, 5 figure
NOEMA observations of GN-z11: Constraining Neutral Interstellar Medium and Dust Formation in the Heart of Cosmic Reionization at
We present results of dust continuum and [CII] emission
line observations of a remarkably UV-luminous () galaxy at
: GN-z11. Using the Northern Extended Millimeter Array (NOEMA),
observations have been carried out over multiple observing cycles. We achieved
a high sensitivity resulting in a
continuum depth of and a [CII] emission
line sensitivity of using
binning with a synthesized beam. Neither dust continuum
nor [CII] line emission are detected at the expected
frequency of and the sky location of
GN-z11. The upper limits show that GN-z11 is neither luminous in
nor , with a dust mass limit of and with a [CII] based molecular gas mass
limit of .
Together with radiative transfer calculations, we also investigated the
possible cause of the dust poor nature of the GN-z11 showed by the blue color
in the UV continuum of GN-z11 (), and found that
deeper observations are crucial to study dust production at
very high-redshift. Nevertheless, our observations show the crucial role of
deep mm/submm observations of very high redshift galaxies to constrain multiple
phases in the interstellar medium.Comment: submitted to MNRAS, 7 pages, 4 figures, 1 tabl
Long-term benefits of nevirapine-containing regimens: multicenter study with 506 patients, followed-up a median of 9 years
[Abstract] OBJECTIVE: To evaluate long-term outcomes in patients maintaining a nevirapine (NVP)-based regimen.
METHODS: Retrospective, multicenter, cohort study including patients currently receiving an NVP regimen that had been started at least 5 years previously. Demographic, clinical, and analytical variables were recorded.
RESULTS: Median follow-up was 8.9 (5.7-11.3) years. Baseline characteristics: 74% men, 47 years old, 36% drug users, 40% AIDS, 40% HCV+, 51.4% detectable HIV-1 viral load, CD4 count 395 (4-1,421)/μL, 19% CD4 3.37 mmol/L significantly decreased in a subsample with available values. A significant decrease in transaminases, alkaline phosphatase, and Fib4 score was observed, mainly in HCV+ and ARV-naive patients.
CONCLUSIONS: In patients who tolerate NVP therapy, (even those with HCV coinfection), long term benefits may be significant in terms of a progressive improvement in general health status markers and CD4 response, a favorable lipid profile, and good liver tolerability
Unveiling the hidden universe with JWST: The contribution of dust-obscured galaxies to the stellar mass function at
The emergence of massive, optically-faint galaxies in infrared observations
has revealed that our view of the high-redshift Universe was previously
incomplete. With the advent of JWST, we can for the first time probe the
rest-frame optical emission of galaxies at with high sensitivity and
spatial resolution, thus moving towards a more complete census of the galaxy
population at high redshifts. To this end, we present a sample of 148 massive,
dusty galaxies from the JWST/CEERS survey, colour-selected using solely JWST
bands. With deep JWST/NIRCam data from 1.15m to 4.44m and ancillary
HST/ACS and WFC3 data, we determine the physical properties of our sample using
spectral energy distribution fitting with BAGPIPES. We demonstrate that our
selection method efficiently identifies massive () and dusty () sources, with a majority at and predominantly lying on the
galaxy main-sequence. The main results of this work are the stellar mass
functions (SMF) of red, optically-faint galaxies from redshifts between
: these galaxies make up a significant fraction of the pre-JWST total
SMF at , and dominate the high-mass end of the pre-JWST SMF at
and , suggesting that our census of the galaxy population needs
amendment at these epochs. While larger areas need to be surveyed in the
future, our results suggest already that the integrated stellar mass density at
may have been underestimated by
20-25% at , and 110% at .Comment: 19 pages, 10 figures, submitted to MNRA
Reionization Era Bright Emission Line Survey: selection and characterization of luminous interstellar medium reservoirs in the z > 6.5 universe
The Reionization Era Bright Emission Line Survey (REBELS) is a cycle-7 ALMA Large Program (LP) that is identifying and performing a first characterization of many of the most luminous star-forming galaxies known in the z > 6.5 universe. REBELS is providing this probe by systematically scanning 40 of the brightest UV-selected galaxies identified over a 7 deg2 area for bright [C ii]158 μm and [O iii]88 μm lines and dust-continuum emission. Selection of the 40 REBELS targets was done by combining our own and other photometric selections, each of which is subject to extensive vetting using three completely independent sets of photometry and template-fitting codes. Building on the observational strategy deployed in two pilot programs, we are increasing the number of massive interstellar medium (ISM) reservoirs known at z > 6.5 by ∼4-5× to >30. In this manuscript, we motivate the observational strategy deployed in the REBELS program and present initial results. Based on the first-year observations, 18 highly significant ≥ 7σ [C ii]158 μm lines have already been discovered, the bulk of which (13/18) also show ≥3.3σ dust-continuum emission. These newly discovered lines more than triple the number of bright ISM-cooling lines known in the z > 6.5 universe, such that the number of ALMA-derived redshifts at z > 6.5 rival Lyα discoveries. An analysis of the completeness of our search results versus star formation rate (SFR) suggests an ∼79% efficiency in scanning for [C ii]158 μm when the SFRUV+IR is >28 M yr-1. These new LP results further demonstrate ALMA's efficiency as a "redshift machine,"particularly in the Epoch of Reionization
The ALMA REBELS survey: obscured star formation in massive Lyman-break galaxies at z = 4-8 revealed by the IRX- and relations
We investigate the degree of dust obscured star formation in 49 massive
() Lyman-break galaxies (LBGs) at
- observed as part of the ALMA Reionization Era Bright Emission
Line Survey (REBELS) large program. By creating deep stacks of the photometric
data and the REBELS ALMA measurements we determine the average rest-frame UV,
optical and far-infrared (FIR) properties which reveal a significant fraction
(-) of obscured star formation, consistent with
previous studies. From measurements of the rest-frame UV slope, we find that
the brightest LBGs at these redshifts show bluer () colours
than expected from an extrapolation of the colour-magnitude relation found at
fainter magnitudes. Assuming a modified blackbody spectral-energy distribution
(SED) in the FIR (with dust temperature of and
), we find that the REBELS sources are in agreement with
the local ''Calzetti-like'' starburst Infrared-excess (IRX)- relation.
By reanalysing the data available for 108 galaxies at - from the
ALPINE ALMA large program using a consistent methodology and assumed FIR SED,
we show that from -, massive galaxies selected in the rest-frame
UV have no appreciable evolution in their derived IRX- relation. When
comparing the IRX- relation derived from the combined ALPINE and
REBELS sample to relations established at , we find a deficit in the
IRX, indicating that at the proportion of obscured star formation is
lower by a factor of at a given a . Our IRX-
results are in good agreement with the high-redshift predictions of simulations
and semi-analytic models for galaxies with similar stellar masses
and SFRs.Comment: 18 pages, 10 figures, 2 tables (plus 1 figure and 2 tables in the
appendix). Updated to match MNRAS accepted version after minor correction
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