2,135 research outputs found
Thirty-fold: Extreme gravitational lensing of a quiescent galaxy at
We report the discovery of eMACSJ1341-QG-1, a quiescent galaxy at
located behind the massive galaxy cluster eMACSJ1341.92442 (). The
system was identified as a gravitationally lensed triple image in Hubble Space
Telescope images obtained as part of a snapshot survey of the most X-ray
luminous galaxy clusters at and spectroscopically confirmed in
ground-based follow-up observations with the ESO/X-Shooter spectrograph. From
the constraints provided by the triple image, we derive a first, crude model of
the mass distribution of the cluster lens, which predicts a gravitational
amplification of a factor of 30 for the primary image and a factor of
6 for the remaining two images of the source, making eMACSJ1341-QG-1 by
far the most strongly amplified quiescent galaxy discovered to date. Our
discovery underlines the power of SNAPshot observations of massive, X-ray
selected galaxy clusters for lensing-assisted studies of faint background
populations
Instability of the expression of morphological and phenological descriptors to environmental variation in white oat.
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Neural responses to facial and vocal expressions of fear and disgust
Neuropsychological studies report more impaired responses to facial expressions of fear than disgust in people with amygdala lesions, and vice versa in people with Huntington's disease. Experiments using functional magnetic resonance imaging (fMRI) have confirmed the role of the amygdala in the response to fearful faces and have implicated the anterior insula in the response to facial expressions of disgust. We used fMRI to extend these studies to the perception of fear and disgust from both facial and vocal expressions. Consistent with neuropsychological findings, both types of fearful stimuli activated the amygdala. Facial expressions of disgust activated the anterior insula and the caudate-putamen; vocal expressions of disgust did not significantly activate either of these regions. All four types of stimuli activated the superior temporal gyrus. Our findings therefore (i) support the differential localization of the neural substrates of fear and disgust; (ii) confirm the involvement of the amygdala in the emotion of fear, whether evoked by facial or vocal expressions; (iii) confirm the involvement of the anterior insula and the striatum in reactions to facial expressions of disgust; and (iv) suggest a possible general role for the perception of emotional expressions for the superior temporal gyrus
The assembly of "normal" galaxies at z=7 probed by ALMA
We report new deep ALMA observations aimed at investigating the [CII]158um
line and continuum emission in three spectroscopically confirmed Lyman Break
Galaxies at 6.8<z<7.1, i.e. well within the re-ionization epoch. With Star
Formation Rates of SFR ~ 5-15 Msun/yr these systems are much more
representative of the high-z galaxy population than other systems targeted in
the past by millimeter observations. For the galaxy with the deepest
observation we detect [CII] emission at redshift z=7.107, fully consistent with
the Lyalpha redshift, but spatially offset by 0.7" (4 kpc) from the optical
emission. At the location of the optical emission, tracing both the Lyalpha
line and the far-UV continuum, no [CII] emission is detected in any of the
three galaxies, with 3sigma upper limits significantly lower than the [CII]
emission observed in lower reshift galaxies. These results suggest that
molecular clouds in the central parts of primordial galaxies are rapidly
disrupted by stellar feedback. As a result, [CII] emission mostly arises from
more external accreting/satellite clumps of neutral gas. These findings are in
agreement with recent models of galaxy formation. Thermal far-infrared
continuum is not detected in any of the three galaxies. However, the upper
limits on the infrared-to-UV emission ratio do not exceed those derived in
metal- and dust-poor galaxies.Comment: 15 pages, 9 figures, MNRAS in press, replaced with accepted versio
The Evolution of the Stellar Mass Functions of Star-Forming and Quiescent Galaxies to z = 4 from the COSMOS/UltraVISTA Survey
We present measurements of the stellar mass functions (SMFs) of star-forming
and quiescent galaxies to z = 4 using a sample of 95 675 galaxies in the
COSMOS/UltraVISTA field. Sources have been selected from the DR1 UltraVISTA
K_{s}-band imaging which covers a unique combination of a wide area (1.62
deg^2), to a significant depth (K_{s,tot} = 23.4). The SMFs of the combined
population are in good agreement with previous measurements and show that the
stellar mass density of the universe was only 50%, 10% and 1% of its current
value at z ~ 0.75, 2.0, and 3.5, respectively. The quiescent population drives
most of the overall growth, with the stellar mass density of these galaxies
increasing by 2.71^{+0.93}_{-0.22} dex since z = 3.5. At z > 2.5, star-forming
galaxies dominate the total SMF at all stellar masses, although a nonzero
population of quiescent galaxies persists to z = 4. Comparisons of the
K_{s}-selected star-forming galaxy SMFs to UV-selected SMFs at 2.5 < z < 4 show
reasonable agreement and suggests UV-selected samples are representative of the
majority of the stellar mass density at z > 3.5. We estimate the average mass
growth of individual galaxies by selecting galaxies at fixed cumulative number
density. The average galaxy with Log(M_{*}/M_{sun}) = 11.5 at z = 0.3 has grown
in mass by only 0.2 dex (0.3 dex) since z = 2.0(3.5), whereas those with
Log(M_{*}/M_{sun}) = 10.5 have grown by > 1.0 dex since z = 2. At z < 2, the
time derivatives of the mass growth are always larger for lower-mass galaxies,
which demonstrates that the mass growth in galaxies since that redshift is
mass-dependent and primarily bottom-up. Lastly, we examine potential sources of
systematic uncertainties on the SMFs and find that those from photo-z
templates, SPS modeling, and the definition of quiescent galaxies dominate the
total error budget in the SMFs.Comment: 18 pages paper, 12 pages appendix, 23 figures. Accepted for
publication in the Ap
A Public Ks-selected Catalog in the COSMOS/UltraVISTA Field: Photometry, Photometric Redshifts and Stellar Population Parameters
We present a catalog covering 1.62 deg^2 of the COSMOS/UltraVISTA field with
PSF-matched photometry in 30 photometric bands. The catalog covers the
wavelength range 0.15um - 24um including the available GALEX, Subaru, CFHT,
VISTA and Spitzer data. Catalog sources have been selected from the DR1
UltraVISTA Ks band imaging that reaches a depth of K_{s,tot} = 23.4 AB (90%
completeness). The PSF-matched catalog is generated using position-dependent
PSFs ensuring accurate colors across the entire field. Also included is a
catalog of photometric redshifts (z_phot) for all galaxies computed with the
EAZY code. Comparison with spectroscopy from the zCOSMOS 10k bright sample
shows that up to z ~ 1.5 the z_phot are accurate to dz/(1 + z) = 0.013, with a
catastrophic outlier fraction of only 1.6%. The z_phot also show good agreement
with the z_phot from the NEWFIRM Medium Band Survey (NMBS) out to z ~ 3. A
catalog of stellar masses and stellar population parameters for galaxies
determined using the FAST spectral energy distribution fitting code is provided
for all galaxies. Also included are rest-frame U-V and V-J colors, L_2800 and
L_IR. The UVJ color-color diagram confirms that the galaxy bi-modality is
well-established out to z ~ 2. Star-forming galaxies also obey a star forming
"main sequence" out to z ~ 2.5, and this sequence evolves in a manner
consistent with previous measurements. The COSMOS/UltraVISTA Ks-selected
catalog covers a unique parameter space in both depth, area, and
multi-wavelength coverage and promises to be a useful tool for studying the
growth of the galaxy population out to z ~ 3 - 4.Comment: 20 pages, 14 figures. Accepted to the ApJSS. Catalog data products
available for download here:
http://www.strw.leidenuniv.nl/galaxyevolution/ULTRAVISTA
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