365 research outputs found
VLT/MUSE view of the highly ionized outflow cones in the nearby starburst ESO338-IG04
The Ly line is an important diagnostic for star formation at high
redshift, but interpreting its flux and line profile is difficult because of
the resonance nature of Ly. Trends between the escape of Ly
photons and dust and properties of the interstellar medium (ISM) have been
found, but detailed comparisons between Ly emission and the properties
of the gas in local high-redshift analogs are vital for understanding the
relation between Ly emission and galaxy properties. For the first time,
we can directly infer the properties of the ionized gas at the same location
and similar spatial scales of the extended Ly halo around ESO 338-IG04.
We obtained VLT/MUSE integral field spectra. We used ionization parameter
mapping of the [SII]/[OIII] line ratio and the kinematics of H to study
the ionization state and kinematics of the ISM of ESO338-IG04. The velocity map
reveals two outflows. The entire central area of the galaxy is highly ionized
by photons leaking from the HII regions around the youngest star clusters.
Three highly ionized cones have been identified, of which one is associated
with an outflow. We propose a scenario where the outflows are created by
mechanical feedback of the older clusters, while the highly ionized gas is
caused by the hard ionizing photons emitted by the youngest clusters. A
comparison with the Ly map shows that the (approximately bipolar)
asymmetries observed in the Ly emission are consistent with the base of
the outflows detected in H. No clear correlation with the ionization
cones is found. The mechanical and ionization feedback of star clusters
significantly changes the state of the ISM by creating ionized cones and
outflows. The comparison with Ly suggests that especially the outflows
could facilitate the escape of Ly photons [Abridged].Comment: Accepted for publication in A&A Letters, 4 pages, 2 figure
Teleological Reasoning in 4-Month-Old Infants: Pupil Dilations and Contextual Constraints
Four-month-old infants were presented with feeding actions performed in a rational or irrational manner. Infants reacted to the irrational feeding actions by dilating their pupils, but only in the presence of rich contextual constraints. The study demonstrates that teleological processes are online at 4 months of age and illustrates the usefulness of pupil dilations as a measure of social cognitive processes early in infancy
O VI Emission Imaging of a Galaxy with the Hubble Space Telescope: a Warm Gas Halo Surrounding the Intense Starburst SDSS J115630.63+500822.1
We report results from a new HST study of the OVI 1032,1038\AA\ doublet in
emission around intensely star-forming galaxies. The programme aims to
characterize the energy balance in starburst galaxies and gas cooling in the
difficult-to-map coronal temperature regime of 2-5 x K. We present the
first resolved image of gas emission in the OVI line. Our target, SDSS
J1156+5008, is very compact in the continuum but displays OVI emission to radii
of 23 kpc. The surface brightness profile is well fit by an exponential with a
scale of 7.5kpc. This is ten times the size of the photoionized gas, and we
estimate that 1/6 the total OVI luminosity comes from resonantly scattered
continuum radiation. Spectroscopy - which closely resembles a stacked sample of
archival spectra - confirms the OVI emission, and determines the column density
and outflow velocity from blueshifted absorption. The combination of
measurements enables several new calculations with few assumptions. The OVI
regions fill only ~ of the volume. By comparing the cooling time with
the cloud sound-crossing time, the cooling distance with the size, and the
pressure in the OVI and nebular gas, we conclude that the OVI-bearing gas
cannot have been lifted to the scale height at this temperature, and must be
cooling in situ through this coronal temperature regime. The coronal phase
contains ~1% of the ionized mass, and its kinetic energy is currently ~1% of
the budget set by supernova feedback. However a much larger amount of the gas
must have cooled through this phase during the star formation episode. The
outflow exceeds the escape velocity and the gas may become unbound, but it will
recombine before it escapes and become visible to Lyman (and OI) spectroscopy.
The mapping of this gas represents a crucial step in further constraining
galaxy formation scenarios and guiding the development of future satellites.Comment: Accepted by the Astrophysical Journal. 25 pages, 11 figures. Section
7 presents calculated properties of warm halo gas. Version 2 fixes PDF
compatibility issue for some PDF viewer
Super star cluster feedback driving ionization, shocks and outflows in the halo of the nearby starburst ESO 338-IG04
Stellar feedback strongly affects the interstellar medium (ISM) of galaxies.
Stellar feedback in the first galaxies likely plays a major role in enabling
the escape of LyC photons, which contribute to the re-ionization of the
Universe. Nearby starburst galaxies serve as local analogues allowing for a
spatially resolved assessment of the feedback processes in these galaxies. We
characterize the feedback effects from the star clusters in the local
high-redshift analogue ESO 338-IG04 on the ISM and compare the results with the
properties of the most massive clusters. We use high quality VLT/MUSE optical
integral field data to derive the physical properties of the ISM such as
ionization, density, shocks, and perform new fitting of the spectral energy
distributions of the brightest clusters in ESO 338-IG04 from HST imaging. ESO
338-IG04 has a large ionized halo which we detect to a distance of 9 kpc. We
identify 4 Wolf-Rayet (WR) clusters based on the blue and red WR bump. We
follow previously identified ionization cones and find that the ionization of
the halo increases with distance. Analysis of the galaxy kinematics shows two
complex outflows driven by the numerous young clusters in the galaxy. We find a
ring of shocked emission traced by an enhanced [OI]/H ratio surrounding
the starburst and at the end of the outflow. Finally we detect nitrogen
enriched gas associated with the outflow, likely caused by the WR stars in the
massive star clusters. Photo-ionization dominates the central starburst and
sets the ionization structure of the entire halo, resulting in a density
bounded halo, facilitating the escape of LyC photons. Outside the central
starburst, shocks triggered by an expanding super bubble become important. The
shocks at the end of the outflow suggest interaction between the hot outflowing
material and the more quiescent halo gas.Comment: Accepted for publication in Astronomy and Astrophysics, 22 pages, 15
figure
Verbal and nonverbal memory in school-aged children born to opioid-dependent mothers
Background: The potential long-term developmental effects of prenatal methadone and buprenorphine exposure during pregnancy are still largely unknown.
Aims: We investigated memory function in school-aged children of women enrolled in opioid maintenance therapy (OMT) during pregnancy.
Study design: Prospective longitudinal cohort study.
Subjects: Participants included 41 children (aged 9â11 years), 20 of which had histories of prenatal methadone or buprenorphine exposure.
Outcome measures: Verbal and non-verbal memory function was assessed using four subtests from the Test of Memory and Learning - Second edition (TOMAL-2).
Results: The OMT group scored lower on both the two non-verbal as well as the two verbal memory tasks, all p-values <.05. Group differences remained for three out of the four subtests after controlling for general IQ. Including maternal tobacco use during pregnancy increased the explanatory power of the model, R2 change of 0.07, p = .04.
Conclusions: Children prenatally exposed to methadone or buprenorphine had significantly lower memory performance, however, this association may in part be explained by maternal tobacco use during pregnancy. Consequently, smoking cessation programs should be systematically integrated into opioid maintenance therapy programs for pregnant women.publishedVersio
MUSE Illuminates Channels for Lyman Continuum Escape in the Halo of SBS 0335-52E
We report on the discovery of ionised gas filaments in the circum-galactic
halo of the extremely metal-poor compact starburst SBS 0335-052E in a 1.5h
integration with the MUSE integral-field spectrograph. We detect these features
in H and [OIII] emission down to surface-brightness levels of erg scmarcsec. The filaments have
projected diameters of 2.1 kpc and extend more than 9 kpc to the north and
north-west from the main stellar body. We also detect extended nebular HeII
4686 emission that brightens towards the north-west at the rim of a
star-burst driven super-shell, suggestive of a locally enhanced UV radiation
field due to shocks. We also present a velocity field of the ionised gas. The
filaments appear to connect seamlessly in velocity space to the kinematical
disturbances caused by the shell. Similar to high- star-forming galaxies,
the ionised gas in this galaxy is dispersion dominated. We argue that the
filaments were created via feedback from the starburst and that these ionised
structures in the halo may act as escape channels for Lyman continuum radiation
in this gas-rich system.Comment: Revised version after peer review. Accepted for publication in A&A
letter
A search for Population III galaxies in CLASH. I. Singly-imaged candidates at high redshift
Population III galaxies are predicted to exist at high redshifts and may be
rendered sufficiently bright for detection with current telescopes when
gravitationally lensed by a foreground galaxy cluster. Population III galaxies
that exhibit strong Lya emission should furthermore be identifiable from
broadband photometry because of their unusual colors. Here, we report on a
search for such objects at z > 6 in the imaging data from the Cluster Lensing
And Supernova survey with Hubble (CLASH), covering 25 galaxy clusters in 16
filters. Our selection algorithm returns five singly-imaged candidates with
Lya-like color signatures, for which ground-based spectroscopy with current
8-10 m class telescopes should be able to test the predicted strength of the
Lya line. None of these five objects have been included in previous CLASH
compilations of high-redshift galaxy candidates. However, when large grids of
spectral synthesis models are applied to the study of these objects, we find
that only two of these candidates are significantly better fitted by Population
III models than by more mundane, low-metallicity stellar populations.Comment: 18 pages, 10 figures, accepted by Ap
Look Who's Talking: Pre-Verbal Infantsâ Perception of Face-to-Face and Back-to-Back Social Interactions
Four-, 6-, and 11-month old infants were presented with movies in which two adult actors conversed about everyday events, either by facing each other or looking in opposite directions. Infants from 6 months of age made more gaze shifts between the actors, in accordance with the flow of conversation, when the actors were facing each other. A second experiment demonstrated that gaze following alone did not cause this difference. Instead the results are consistent with a social cognitive interpretation, suggesting that infants perceive the difference between face-to-face and back-to-back conversations and that they prefer to attend to a typical pattern of social interaction from 6 months of age
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