3,999 research outputs found
Measures of galaxy dust and gas mass with Herschel photometry and prospects for ALMA
(Abridged) Combining the deepest Herschel extragalactic surveys (PEP,
GOODS-H, HerMES), and Monte Carlo mock catalogs, we explore the robustness of
dust mass estimates based on modeling of broad band spectral energy
distributions (SEDs) with two popular approaches: Draine & Li (2007, DL07) and
a modified black body (MBB). As long as the observed SED extends to at least
160-200 micron in the rest frame, M(dust) can be recovered with a >3 sigma
significance and without the occurrence of systematics. An average offset of a
factor ~1.5 exists between DL07- and MBB-based dust masses, based on consistent
dust properties. At the depth of the deepest Herschel surveys (in the GOODS-S
field) it is possible to retrieve dust masses with a S/N>=3 for galaxies on the
main sequence of star formation (MS) down to M(stars)~1e10 [M(sun)] up to z~1.
At higher redshift (z<=2) the same result is achieved only for objects at the
tip of the MS or lying above it. Molecular gas masses, obtained converting
M(dust) through the metallicity-dependent gas-to-dust ratio delta(GDR), are
consistent with those based on the scaling of depletion time, and on CO
spectroscopy. Focusing on CO-detected galaxies at z>1, the delta(GDR)
dependence on metallicity is consistent with the local relation. We combine
far-IR Herschel data and sub-mm ALMA expected fluxes to study the advantages of
a full SED coverage.Comment: Accepted for publication in Astronomy and Astrophysics. Some figures
have degraded quality for filesize reason
Peritoneal fluid modifies the response of human spermatozoa to follicular fluid
The aim of this study was to elucidate the mechanism involved in the acrosome reaction (AR) induced by follicular fluid (FF) in spermatozoa previously exposed to peritoneal fluid (PF). The influence of progesterone was also investigated. Semen samples were from 18 normozoospermic donors. PF samples were from 13 women with unexplained infertility and from a woman treated with synthetic progestagen. FF samples were collected from six women undergoing IVF/embryo transfer and pooled. Motile spermatozoa were capacitated overnight and a kinetic and inhibition study on the FF-induced AR was performed. Spermatozoa pretreated with PF were challenged with either FF or progesterone. The ability of progesterone- and progestagen-supplemented PF to induce AR was analysed. Enzyme-digested PF was also tested. Pre-incubation with PF for 60 min completely prevented the FF-induced AR; spermatozoa treated with PF were unable to respond to FF or progesterone and this effect was not reversible. Progesterone- and progestagen-supplemented PF stimulated the AR relative to controls. Enzyme-digested PF did not have an inhibitory capacity. These data strongly suggest that there are one or more inhibitory proteins in PF that interact with spermatozoa so as to prevent access of progesterone to its receptor and thus inhibit the occurrence of the AR. The oviduct, or Fallopian tube, provides a place for spermatozoa and egg transport and storage, fertilization and early embryo development. If ovulation has not occurred, spermatozoa may reside in the oviduct for several hours or even a few days, awaiting oocyte arrival. It is assumed that fluids present in the female genital tract may have a role in synchronizing the timing required to guarantee the success of fertilization. We previously observed that the peritoneal fluid that bathes the peritoneal cavity is a suitable medium for sperm survival and we also reported that this fluid could stabilize spermatozoa. In this study we show further evidence that the exposure to peritoneal fluid modifies the response of spermatozoa to oocyte signals.Fil: Caille, Adriana M.. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; ArgentinaFil: Berta, Cesar L.. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; ArgentinaFil: Cuasnicu, Patricia Sara. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental (i); Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; ArgentinaFil: Munuce, María J.. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; Argentin
The Far-Infrared, UV and Molecular Gas Relation in Galaxies up to z=2.5
We use the infrared excess (IRX) FIR/UV luminosity ratio to study the
relation between the effective UV attenuation (A_IRX) and the UV spectral slope
(beta) in a sample of 450 1<z<2.5 galaxies. The FIR data is from very deep
Herschel observations in the GOODS fields that allow us to detect galaxies with
SFRs typical of galaxies with log(M)>9.3. Thus, we are able to study galaxies
on and even below the main SFR-stellar mass relation (main sequence). We find
that main sequence galaxies form a tight sequence in the IRX--beta plane, which
has a flatter slope than commonly used relations. This slope favors a SMC-like
UV extinction curve, though the interpretation is model dependent. The scatter
in the IRX-beta plane, correlates with the position of the galaxies in the
SFR-M plane. Using a smaller sample of galaxies with CO gas masses, we study
the relation between the UV attenuation and the molecular gas content. We find
a very tight relation between the scatter in the IRX-beta plane and the
specific attenuation (S_A), a quantity that represents the attenuation
contributed by the molecular gas mass per young star. S_A is sensitive to both
the geometrical arrangement of stars and dust, and to the compactness of the
star forming regions. We use this empirical relation to derive a method for
estimating molecular gas masses using only widely available integrated
rest-frame UV and FIR photometry. The method produces gas masses with an
accuracy between 0.12-0.16 dex in samples of normal galaxies between z~0 and
z~1.5. Major mergers and sub-millimeter galaxies follow a different S_A
relation.Comment: 11 pages, 6 pages appendix, 11 figures, accepted to Ap
ISM conditions in z~0.2 Lyman-Break Analogs
We present an analysis of far--infrared (FIR) [CII] and [OI] fine structure
line and continuum observations obtained with /PACS, and CO(1-0)
observations obtained with the IRAM Plateau de Bure Interferometer, of Lyman
Break Analogs (LBAs) at . The principal aim of this work is to
determine the typical ISM properties of Main Sequence (MS)
galaxies, with stellar masses between and ,
which are currently not easily detectable in all these lines even with ALMA and
NOEMA. We perform PDR modeling and apply different IR diagnostics to derive the
main physical parameters of the FIR emitting gas and dust and we compare the
derived ISM properties to those of galaxies on and above the MS at different
redshifts. We find that the ISM properties of LBAs are quite extreme (low gas
temperature, high density and thermal pressure) with respect to those found in
local normal spirals and more active local galaxies. LBAs have no [CII] deficit
despite having the high specific star formation rates (sSFRs) typical of
starbursts. Although LBAs lie above the local MS, we show that their ISM
properties are more similar to those of high-redshift MS galaxies than of local
galaxies above the main sequence. This data set represents an important
reference for planning future ALMA [CII] observations of relatively low-mass MS
galaxies at the epoch of the peak of the cosmic star formation.Comment: 19 pages, 12 Figures,8 Tables, Accepted for publication in A&
WASP-4b Arrived Early for the TESS Mission
The Transiting Exoplanet Survey Satellite (TESS) recently observed 18
transits of the hot Jupiter WASP-4b. The sequence of transits occurred 81.6
11.7 seconds earlier than had been predicted, based on data stretching
back to 2007. This is unlikely to be the result of a clock error, because TESS
observations of other hot Jupiters (WASP-6b, 18b, and 46b) are compatible with
a constant period, ruling out an 81.6-second offset at the 6.4 level.
The 1.3-day orbital period of WASP-4b appears to be decreasing at a rate of
milliseconds per year. The apparent period change
might be caused by tidal orbital decay or apsidal precession, although both
interpretations have shortcomings. The gravitational influence of a third body
is another possibility, though at present there is minimal evidence for such a
body. Further observations are needed to confirm and understand the timing
variation.Comment: AJ accepte
The far-infrared/radio correlation and radio spectral index of galaxies in the SFR-M* plane up to z 2
[Abridged] We study the evolution of the radio spectral index and
far-infrared/radio correlation (FRC) across the star-formation rate-stellar
masse (i.e. SFR-M*) plane up to z 2. We start from a M*-selected sample of
galaxies with reliable SFR and redshift estimates. We then grid the SFR-M*
plane in several redshift ranges and measure the infrared luminosity, radio
luminosity, radio spectral index, and ultimately the FRC index (i.e. qFIR) of
each SFR-M*-z bin. The infrared luminosities of our SFR-M*-z bins are estimated
using their stacked far-infrared flux densities inferred from observations
obtained with Herschel. Their radio luminosities and radio spectral indices
(i.e. alpha, where Snu nu^-alpha) are estimated using their stacked 1.4GHz and
610MHz flux densities from the VLA and GMRT, respectively. Our far-infrared and
radio observations include the most widely studied blank extragalactic fields
-GOODS-N/S, ECDFS, and COSMOS- covering a sky area of 2deg^2. Using this
methodology, we constrain the radio spectral index and FRC index of
star-forming galaxies with M*>10^10Msun and 0<z<2.3. We find that
alpha^1.4GHz_610MHz does not evolve significantly with redshift or with the
distance of a galaxy with respect to the main sequence (MS) of the SFR-M* plane
(i.e. Delta_log(SSFR)_MS=log[SSFR(galaxy)/SSFR_MS(M*,z)]). Instead,
star-forming galaxies have a radio spectral index consistent with a canonical
value of 0.8, which suggests that their radio spectra are dominated by
non-thermal optically thin synchrotron emission. We find that qFIR displays a
moderate but statistically significant redshift evolution as
qFIR(z)=(2.35+/-0.08)*(1+z)^(-0.12+/-0.04), consistent with some previous
literature. Finally, we find no significant correlation between qFIR and
Delta_log(SSFR)_MS, though a weak positive trend, as observed in one of our
redshift bins, cannot be firmly ruled out using our dataset.Comment: Accepted for publication in A&A; 18 pages, 10 figure
Dust temperature and CO-to-H2 conversion factor variations in the SFR-M* plane
Deep Herschel imaging and 12CO(2-1) line luminosities from the IRAM PdBI are
combined for a sample of 17 galaxies at z>1 from the GOODS-N field. The sample
includes galaxies both on and above the main sequence (MS) traced by
star-forming galaxies in the SFR-M* plane. The far-infrared data are used to
derive dust masses, Mdust. Combined with an empirical prescription for the
dependence of the gas-to-dust ratio on metallicity (GDR), the CO luminosities
and Mdust values are used to derive for each galaxy the CO-to-H2 conversion
factor, alpha_co. Like in the local Universe, the value of alpha_co is a factor
of ~5 smaller in starbursts compared to normal star-forming galaxies (SFGs). We
also uncover a relation between alpha_co and dust temperature (Tdust; alpha_co
decreasing with increasing Tdust) as obtained from modified blackbody fits to
the far-infrared data. While the absolute normalization of the alpha_co(Tdust)
relation is uncertain, the global trend is robust against possible systematic
biases in the determination of Mdust, GDR or metallicity. Although we cannot
formally distinguish between a step and a smooth evolution of alpha_co with the
dust temperature, we can conclude that in galaxies of near-solar metallicity, a
critical value of Tdust=30K can be used to determine whether the appropriate
alpha_co is closer to the starburst value (1.0 Msun(K kms pc^2)^-1, if
Tdust>30K) or closer to the Galactic value (4.35 Msun (K kms pc^2)^-1, if
Tdust<30K). This indicator has the great advantage of being less subjective
than visual morphological classifications of mergers/SFGs, which can be
difficult at high z because of the clumpy nature of SFGs. In the absence of
far-infrared data, the offset of a galaxy from the main sequence (i.e.,
log[SSFR(galaxy)/SSFR_MS(M*,z)]) can be used to identify galaxies requiring the
use of an alpha_co conversion factor lower than the Galactic value.Comment: Accepted for publication in Astronomy and Astrophysics (A&A); 15
pages, 6 figures; V2: updated reference lis
Upregulation of the voltage-gated sodium channel beta2 subunit in neuropathic pain models: characterization of expression in injured and non-injured primary sensory neurons
The development of abnormal primary sensory neuron excitability and neuropathic pain symptoms after peripheral nerve injury is associated with altered expression of voltage-gated sodium channels (VGSCs) and a modification of sodium currents. To investigate whether the beta2 subunit of VGSCs participates in the generation of neuropathic pain, we used the spared nerve injury (SNI) model in rats to examine beta2 subunit expression in selectively injured (tibial and common peroneal nerves) and uninjured (sural nerve) afferents. Three days after SNI, immunohistochemistry and Western blot analysis reveal an increase in the beta2 subunit in both the cell body and peripheral axons of injured neurons. The increase persists for >4 weeks, although beta2 subunit mRNA measured by real-time reverse transcription-PCR and in situ hybridization remains unchanged. Although injured neurons show the most marked upregulation,beta2 subunit expression is also increased in neighboring non-injured neurons and a similar pattern of changes appears in the spinal nerve ligation model of neuropathic pain. That increased beta2 subunit expression in sensory neurons after nerve injury is functionally significant, as demonstrated by our finding that the development of mechanical allodynia-like behavior in the SNI model is attenuated in beta2 subunit null mutant mice. Through its role in regulating the density of mature VGSC complexes in the plasma membrane and modulating channel gating, the beta2 subunit may play a key role in the development of ectopic activity in injured and non-injured sensory afferents and, thereby, neuropathic pain
New light on gamma-ray burst host galaxies with Herschel
Until recently, dust emission has been detected in very few host galaxies of
gamma-ray bursts (GRBHs). With Herschel, we have now observed 17 GRBHs up to
redshift z~3 and detected seven of them at infrared (IR) wavelengths. This
relatively high detection rate (41%) may be due to the composition of our
sample which at a median redshift of 1.1 is dominated by the hosts of dark
GRBs. Although the numbers are small, statistics suggest that dark GRBs are
more likely to be detected in the IR than their optically-bright counterparts.
Combining our IR data with optical, near-infrared, and radio data from our own
datasets and from the literature, we have constructed spectral energy
distributions (SEDs) which span up to 6 orders of magnitude in wavelength. By
fitting the SEDs, we have obtained stellar masses, dust masses, star-formation
rate (SFR), and extinctions for our sample galaxies. We find that GRBHs are
galaxies that tend to have a high specfic SFR (sSFR), and like other
star-forming galaxies, their ratios of dust-to-stellar mass are well correlated
with sSFR. We incorporate our Herschel sample into a larger compilation of
GRBHs, and compare this combined sample to SFR-weighted median stellar masses
of the widest, deepest galaxy survey to date. This is done in order to
establish whether or not GRBs can be used as an unbiased tracer of cosmic
comoving SFR density (SFRD) in the universe. In contrast with previous results,
this comparison shows that GRBHs are medium-sized galaxies with relatively high
sSFRs; stellar masses and sSFRs of GRBHs as a function of redshift are similar
to what is expected for star-forming galaxy populations at similar redshifts.
We conclude that there is no strong evidence that GRBs are biased tracers of
SFRD; thus they should be able to reliably probe the SFRD to early epochs.Comment: 18 pages, 9 figures, accepted for publication in A&A. Revised to
include Fig. 6, mistakenly omitted in origina
Herschel Far-IR counterparts of SDSS galaxies: Analysis of commonly used Star Formation Rate estimates
We study a hundred of galaxies from the spectroscopic Sloan Digital Sky
Survey with individual detections in the Far-Infrared Herschel PACS bands (100
or 160 m) and in the GALEX Far-UltraViolet band up to z0.4 in the
COSMOS and Lockman Hole fields. The galaxies are divided into 4 spectral and 4
morphological types. For the star forming and unclassifiable galaxies we
calculate dust extinctions from the UV slope, the H/H ratio and
the ratio. There is a tight correlation between the
dust extinction and both and metallicity. We calculate
SFR and compare it with other SFR estimates (H, UV, SDSS)
finding a very good agreement between them with smaller dispersions than
typical SFR uncertainties. We study the effect of mass and metallicity, finding
that it is only significant at high masses for SFR. For the AGN and
composite galaxies we find a tight correlation between SFR and L
(0.29), while the dispersion in the SFR - L relation is
larger (0.57). The galaxies follow the prescriptions of the
Fundamental Plane in the M-Z-SFR space.Comment: 24 pages, 23 figures, accepted for publication in MNRA
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