ABSTRACT
We exploit deep integral-field spectroscopic observations with KMOS/Very Large Telescope of 240 star-forming disks at
to dynamically constrain their mass budget. Our sample consists of ...massive (
) galaxies with sizes
. By contrasting the observed velocity and dispersion profiles with dynamical models, we find that on average the stellar content contributes
of the total dynamical mass, with a significant spread among galaxies (68th percentile range
). Including molecular gas as inferred from CO- and dust-based scaling relations, the estimated baryonic mass adds up to
of the total for the typical galaxy in our sample, reaching
at
. We conclude that baryons make up most of the mass within the disk regions of high-redshift star-forming disk galaxies, with typical disks at
being strongly baryon-dominated within
R
e
. Substantial object-to-object variations in both stellar and baryonic mass fractions are observed among the galaxies in our sample, larger than what can be accounted for by the formal uncertainties in their respective measurements. In both cases, the mass fractions correlate most strongly with measures of surface density. High-
galaxies feature stellar mass fractions closer to unity, and systems with high inferred gas or baryonic surface densities leave less room for additional mass components other than stars and molecular gas. Our findings can be interpreted as more extended disks probing further (and more compact disks probing less far) into the dark matter halos that host them.
Abstract
We present measurements of the surface density of star formation, the star-forming clump luminosity function, and the clump size distribution function, for the lensed galaxy ...SGAS J111020.0+645950.8 at a redshift of
z
= 2.481. The physical size scales that we probe, radii
r
= 30–50 pc, are considerably smaller scales than have yet been studied at these redshifts. The star formation surface density we find within these small clumps is consistent with surface densities measured previously for other lensed galaxies at similar redshift. Twenty-two percent of the rest-frame ultraviolet light in this lensed galaxy arises from small clumps, with
pc. Within the range of overlap, the clump luminosity function measured for this lensed galaxy is remarkably similar to those of
galaxies. In this galaxy, star-forming regions smaller than 100 pc—physical scales not usually resolved at these redshifts by current telescopes—are important locations of star formation in the distant universe. If this galaxy is representative, this may contradict the theoretical picture in which the critical size scale for star formation in the distant universe is of the order of 1 kpc. Instead, our results suggest that current telescopes have not yet resolved the critical size scales of star-forming activity in galaxies over most of cosmic time.
Abstract
Using the combined resolving power of the
Hubble Space Telescope
and gravitational lensing, we resolve star-forming structures in a
galaxy on scales much smaller than the usual kiloparsec ...diffraction limit of
HST
. SGAS J111020.0+645950.8 is a clumpy, star-forming galaxy lensed by the galaxy cluster SDSS J1110+6459 at
, with a total magnification
across the entire arc. We use a hybrid parametric/non-parametric strong lensing mass model to compute the deflection and magnification of this giant arc, reconstruct the light distribution of the lensed galaxy in the source plane, and resolve the star formation into two dozen clumps. We develop a forward-modeling technique to model each clump in the source plane. We ray-trace the model to the image plane, convolve with the instrumental point-spread function (PSF), and compare with the GALFIT model of the clumps in the image plane, which decomposes clump structure from more extended emission. This technique has the advantage, over ray-tracing, of accounting for the asymmetric lensing shear of the galaxy in the image plane and the instrument PSF. At this resolution, we can begin to study star formation on a clump-by-clump basis, toward the goal of understanding feedback mechanisms and the buildup of exponential disks at high redshift.
This mixed methods study investigates the impact of introducing participatory intrahousehold decision making in Ugandan agricultural households on multiple dimensions of women's empowerment, ...including more subjective aspects of sense of agency and achievements by examining how impact aligns with women's perceptions of the process, meaning and value of their empowerment. Participatory intrahousehold decision making is expected to empower women through increasing their voice and decision-making power and reducing collective action problems within households, which compromise efficiency and equitable sharing of costs and benefits of household farming. Couple seminars raising awareness about participatory intrahousehold decision making promoted women's involvement in strategic farm and household decisions, highly aspired and valued by women to actively contribute to their households' welfare. This may facilitate the pathway to empowerment where women have some leeway to participate in strategic household affairs. Couple seminars made improvement in household welfare more likely. This is an achievement in itself with great meaning to women as it answers to their priorities and sense of agency. Introducing participatory intrahousehold decision making by an additional intensive coaching of couples contributed to women's priority of enhanced access to household coffee income, only feasible in the pathway with room for participation in household affairs.
We present Atacama Large Millimeter/submillimeter Array observations of CO lines and dust continuum emission of the source RCSGA 032727-132609, a young z = 1.7 low-metallicity starburst galaxy. The ...CO(3-2) and CO(6-5) lines and continuum at rest-frame 450 m are detected and show a resolved structure in the image plane. We use the corresponding lensing model to obtain a source plane reconstruction of the detected emissions revealing an intrinsic flux density of Jy and intrinsic CO luminosities and . We used the resolved properties in the source plane to obtain molecular gas and star formation rate surface densities of and , respectively. The intrinsic properties of RCSGA 032727-132609 show an enhanced star formation activity compared to local spiral galaxies with similar molecular gas densities, supporting the ongoing merger-starburst phase scenario. RCSGA 032727-132609 also appears to be a low-density starburst galaxy similar to local blue compact dwarf galaxies, which have been suggested as local analogs to high-redshift low-metallicity starburst systems. Finally, the CO excitation level in the galaxy is consistent with having the peak at , with a higher excitation concentrated in the star-forming clumps.
We combine IRAM Plateau de Bure Interferometer and Herschel PACS and SPIRE measurements to study the dust and gas contents of high-redshift star-forming galaxies. We present new observations for a ...sample of 17 lensed galaxies at z = 1.4-3.1, which allow us to directly probe the cold interstellar medium of normal star-forming galaxies with stellar masses of ~10 super(10) M sub(middot in circle), a regime otherwise not (yet) accessible by individual detections in Herschel and molecular gas studies. The lensed galaxies are combined with reference samples of submillimeter and normal z ~ 1-2 star-forming galaxies with similar far-infrared photometry to study the gas and dust properties of galaxies in the SFR-M sub(*)-redshift parameter space. The depletion timescale and gas fractions of the z > 2 normal star-forming galaxies can be explained under the "equilibrium model" for galaxy evolution, in which the gas reservoir of galaxies is the primary driver of the redshift evolution of specific star formation rates.
We present a detailed analysis of multi-wavelength Hubble Space Telescope/Wide Field Camera 3 (WFC3) imaging and Keck/OSIRIS near-infrared adaptive optics-assisted integral field spectroscopy for a ...highly magnified lensed galaxy at z = 1.70. This young starburst is representative of ultraviolet-selected star-forming galaxies (SFGs) at z ~ 2 and contains multiple individual star-forming regions. Due to the lensing magnification, we can resolve spatial scales down to 100 pc in the source plane of the galaxy. The velocity field shows disturbed kinematics suggestive of an ongoing interaction and there is a clear signature of a tidal tail. We constrain the age, reddening, star formation rate, and stellar mass of the star-forming clumps from spectral energy distribution (SED) modeling of the WFC3 photometry and measure their H alpha luminosity, metallicity, and outflow properties from the OSIRIS data. With strong star-formation-driven outflows in four clumps, RCSGA0327 is the first high-redshift SFG at stellar mass <10 super(10) M sub(middot in circle) with spatially resolved stellar winds. We compare the H alpha luminosities, sizes, and dispersions of the star-forming regions with other high-z clumps as well as local giant H II regions and find no evidence for increased clump star formation surface densities in interacting systems, unlike in the local universe. Spatially resolved SED modeling unveils an established stellar population at the location of the largest clump and a second mass concentration near the edge of the system that is not detected in H alpha emission. This suggests a picture of an equal-mass mixed major merger, which has not triggered a new burst of star formation or caused a tidal tail in the gas-poor component.
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