60 research outputs found
Dissecting the Mid-Infrared Heart of M83 with JWST
We present a first look at the MRS observations of the nucleus of the spiral
galaxy M83, taken with MIRI onboard JWST. The observations show a rich set of
emission features from the ionized and warm molecular gas, as well as traces of
the dust properties in this highly star forming environment. To begin
dissecting the complex processes taking place in this part of the galaxy, we
divide the nucleus observations into four different regions. We find that the
strength of the emission features appears to strongly vary in all four regions,
with the south-east region displaying the weakest features tracing both the
dust continuum and ISM properties. Comparison between the cold molecular gas
traced by the CO (1-0) transition with ALMA and the H 0-0 S(1)
transition showed a similar spatial distribution throughout the nucleus. This
is in contrast to the distribution of the much warmer H emission from the
S(7) transition found to be concentrated mainly around the optical nucleus. We
modeled the H excitation using the rotational emission lines and estimate a
total molecular gas mass accounting for the warm H component of M(50
K) = 59.33 () 10 M. We
compared this value to the total molecular gas mass inferred by probing the
cold H gas through the CO (1-0) emission, M(CO) =
14.99 10 M. Our findings indicate that 75\% of
the total molecular gas mass in the core of M83 is contained in the warm H
component. We also identify [OIV]25.89 m and [FeII]25.99 m emission
(indicative of shocks) in all four nuclear regions with the strongest emission
originating from the north-west section. We propose that the diffuse
[FeII]25.99 m emission is an indication of the combined effects of both
the collective supernova explosions and the starbursts themselves.Comment: 13 pages, 3 Tables, 8 Figures, to be submitted to Ap
Multi-phase gas interactions on subarcsec scales in the shocked IGM of Stephan's Quintet with JWST and ALMA
We combine JWST and HST imaging with ALMA~CO(2-1) spectroscopy to study the
highly turbulent multi-phase intergalactic medium (IGM) in Stephan's Quintet on
25-150 pc scales. Previous Spitzer observations revealed luminous H line
cooling across a 45 kpc-long filament, created by a giant shock-wave, following
the collision with an intruder galaxy NGC~7318b. We demonstrate that the
MIRI/F1000W/F770W filters are dominated by 0-0~S(3)~H and a combination of
PAH and 0-0~S(5)~H emission. They reveal the dissipation of kinetic energy
as massive clouds experience collisions, interactions and likely
destruction/re-cycling within different phases of the IGM. In one kpc-scaled
structure, warm H formed a triangular-shaped head and tail of compressed
and stripped gas behind a narrow shell of cold H. In another region, two
cold molecular clumps with very different velocities are connected by an
arrow-shaped stream of warm, probably shocked, H suggesting a cloud-cloud
collision is occurring. In both regions, a high warm-to-cold molecular gas
fraction indicates that the cold clouds are being disrupted and converted into
warm gas. We also map gas associated with an apparently forming dwarf galaxy.
We suggest that the primary mechanism for exciting strong mid-IR H lines
throughout Stephan's Quintet is through a fog of warm gas created by the
shattering of denser cold molecular clouds and mixing/recycling in the
post-shocked gas. A full picture of the diverse kinematics and excitation of
the warm H will require future JWST mid-IR spectroscopy. The current
observations reveal the rich variety of ways that different gas phases can
interact with one another.Comment: Accepted for Publications to ApJ April 10 202
Infrared molecular hydrogen lines in GRB host galaxies
Molecular species, most frequently H_2, are present in a small, but growing,
number of gamma-ray burst (GRB) afterglow spectra at redshifts z~2-3, detected
through their rest-frame UV absorption lines. In rare cases, lines of
vibrationally excited states of H_2 can be detected in the same spectra. The
connection between afterglow line-of-sight absorption properties of molecular
(and atomic) gas, and the observed behaviour in emission of similar sources at
low redshift, is an important test of the suitability of GRB afterglows as
general probes of conditions in star formation regions at high redshift.
Recently, emission lines of carbon monoxide have been detected in a small
sample of GRB host galaxies, at sub-mm wavelengths, but no searches for H_2 in
emission have been reported yet. In this paper we perform an exploratory search
for rest-frame K band rotation-vibrational transitions of H_2 in emission,
observable only in the lowest redshift GRB hosts (z<0.22). Searching the data
of four host galaxies, we detect a single significant rotation-vibrational H_2
line candidate, in the host of GRB 031203. Re-analysis of Spitzer mid-infrared
spectra of the same GRB host gives a single low significance rotational line
candidate. The (limits on) line flux ratios are consistent with those of blue
compact dwarf galaxies in the literature. New instrumentation, in particular on
the JWST and the ELT, can facilitate a major increase in our understanding of
the H_2 properties of nearby GRB hosts, and the relation to H_2 absorption in
GRBs at higher redshift.Comment: 7 pages, 4 figures, MNRAS accepte
Biallelic mutations in IRF8 impair human NK cell maturation and function
Human NK cell deficiencies are rare yet result in severe and often fatal disease, particularly as a result of viral susceptibility. NK cells develop from hematopoietic stem cells, and few monogenic errors that specifically interrupt NK cell development have been reported. Here we have described biallelic mutations in IRF8, which encodes an interferon regulatory factor, as a cause of familial NK cell deficiency that results in fatal and severe viral disease. Compound heterozygous or homozygous mutations in IRF8 in 3 unrelated families resulted in a paucity of mature CD56dim NK cells and an increase in the frequency of the immature CD56bright NK cells, and this impairment in terminal maturation was also observed in Irf8–/–, but not Irf8+/–, mice. We then determined that impaired maturation was NK cell intrinsic, and gene expression analysis of human NK cell developmental subsets showed that multiple genes were dysregulated by IRF8 mutation. The phenotype was accompanied by deficient NK cell function and was stable over time. Together, these data indicate that human NK cells require IRF8 for development and functional maturation and that dysregulation of this function results in severe human disease, thereby emphasizing a critical role for NK cells in human antiviral defense
The clinicopathological significance of miR-1307 in chemotherapy resistant epithelial ovarian cancer
GOALS-JWST: Tracing AGN Feedback on the Star-forming Interstellar Medium in NGC 7469
We present James Webb Space Telescope (JWST) Mid-Infrared Instrument (MIRI) integral-field spectroscopy of the nearby merging, luminous infrared galaxy, NGC 7469. This galaxy hosts a Seyfert type-1.5 nucleus, a highly ionized outflow, and a bright, circumnuclear star-forming ring, making it an ideal target to study active galactic nucleus (AGN) feedback in the local universe. We take advantage of the high spatial/spectral resolution of JWST/ MIRI to isolate the star-forming regions surrounding the central active nucleus and study the properties of the dust and warm molecular gas on ∼100 pc scales. The starburst ring exhibits prominent polycyclic aromatic hydrocarbon (PAH) emission, with grain sizes and ionization states varying by only ∼30%, and a total star formation rate of 10–30 Me yr−1 derived from fine structure and recombination emission lines. Using pure rotational lines of H2 we detect 1.2
7 107 Me of warm molecular gas at a temperature higher than 200 K in the ring. All PAH bands get significantly weaker toward the central source, where larger and possibly more ionized grains dominate the emission, likely the result of the ionizing radiation and/or the fast wind emerging from the AGN. The small grains and warm molecular gas in the bright regions of the ring however display properties consistent with normal star-forming regions. These observations highlight the power of JWST to probe the inner regions of dusty, rapidly evolving galaxies for signatures of feedback and inform models that seek to explain the coevolution of supermassive black holes and their hosts
Msx1 and Msx2 are required for endothelial-mesenchymal transformation of the atrioventricular cushions and patterning of the atrioventricular myocardium
<p>Abstract</p> <p>Background</p> <p><it>Msx1 </it>and <it>Msx2</it>, which belong to the highly conserved <it>Nk </it>family of homeobox genes, display overlapping expression patterns and redundant functions in multiple tissues and organs during vertebrate development. <it>Msx1 </it>and <it>Msx2 </it>have well-documented roles in mediating epithelial-mesenchymal interactions during organogenesis. Given that both <it>Msx1 </it>and <it>Msx2 </it>are crucial downstream effectors of Bmp signaling, we investigated whether <it>Msx1 </it>and <it>Msx2 </it>are required for the Bmp-induced endothelial-mesenchymal transformation (EMT) during atrioventricular (AV) valve formation.</p> <p>Results</p> <p>While both <it>Msx1-/- </it>and <it>Msx2-/- </it>single homozygous mutant mice exhibited normal valve formation, we observed hypoplastic AV cushions and malformed AV valves in <it>Msx1-/-; Msx2-/- </it>mutants, indicating redundant functions of <it>Msx1 </it>and <it>Msx2 </it>during AV valve morphogenesis. In <it>Msx1/2 </it>null mutant AV cushions, we found decreased Bmp2/4 and <it>Notch1 </it>signaling as well as reduced expression of <it>Has2</it>, <it>NFATc1 </it>and <it>Notch1</it>, demonstrating impaired endocardial activation and EMT. Moreover, perturbed expression of chamber-specific genes <it>Anf</it>, <it>Tbx2</it>, <it>Hand1 </it>and <it>Hand2 </it>reveals mispatterning of the <it>Msx1/2 </it>double mutant myocardium and suggests functions of <it>Msx1 </it>and <it>Msx2 </it>in regulating myocardial signals required for remodelling AV valves and maintaining an undifferentiated state of the AV myocardium.</p> <p>Conclusion</p> <p>Our findings demonstrate redundant roles of <it>Msx1 </it>and <it>Msx2 </it>in regulating signals required for development of the AV myocardium and formation of the AV valves.</p
A far-ultraviolet-driven photoevaporation flow observed in a protoplanetary disk.
Most low-mass stars form in stellar clusters that also contain massive stars, which are sources of far-ultraviolet (FUV) radiation. Theoretical models predict that this FUV radiation produces photodissociation regions (PDRs) on the surfaces of protoplanetary disks around low-mass stars, which affects planet formation within the disks. We report James Webb Space Telescope and Atacama Large Millimeter Array observations of a FUV-irradiated protoplanetary disk in the Orion Nebula. Emission lines are detected from the PDR; modeling their kinematics and excitation allowed us to constrain the physical conditions within the gas. We quantified the mass-loss rate induced by the FUV irradiation and found that it is sufficient to remove gas from the disk in less than a million years. This is rapid enough to affect giant planet formation in the disk
PDRs4All IV. An embarrassment of riches: Aromatic infrared bands in the Orion Bar
(Abridged) Mid-infrared observations of photodissociation regions (PDRs) are
dominated by strong emission features called aromatic infrared bands (AIBs).
The most prominent AIBs are found at 3.3, 6.2, 7.7, 8.6, and 11.2 m. The
most sensitive, highest-resolution infrared spectral imaging data ever taken of
the prototypical PDR, the Orion Bar, have been captured by JWST. We provide an
inventory of the AIBs found in the Orion Bar, along with mid-IR template
spectra from five distinct regions in the Bar: the molecular PDR, the atomic
PDR, and the HII region. We use JWST NIRSpec IFU and MIRI MRS observations of
the Orion Bar from the JWST Early Release Science Program, PDRs4All (ID: 1288).
We extract five template spectra to represent the morphology and environment of
the Orion Bar PDR. The superb sensitivity and the spectral and spatial
resolution of these JWST observations reveal many details of the AIB emission
and enable an improved characterization of their detailed profile shapes and
sub-components. While the spectra are dominated by the well-known AIBs at 3.3,
6.2, 7.7, 8.6, 11.2, and 12.7 m, a wealth of weaker features and
sub-components are present. We report trends in the widths and relative
strengths of AIBs across the five template spectra. These trends yield valuable
insight into the photochemical evolution of PAHs, such as the evolution
responsible for the shift of 11.2 m AIB emission from class B in
the molecular PDR to class A in the PDR surface layers. This
photochemical evolution is driven by the increased importance of FUV processing
in the PDR surface layers, resulting in a "weeding out" of the weakest links of
the PAH family in these layers. For now, these JWST observations are consistent
with a model in which the underlying PAH family is composed of a few species:
the so-called 'grandPAHs'.Comment: 25 pages, 10 figures, to appear in A&
- …