This paper presents a spatially resolved kinematic study of the jellyfish galaxy JO201, one of the most spectacular cases of ram-pressure stripping (RPS) in the GAs Stripping Phenomena in galaxies ...with MUSE (GASP) survey. By studying the environment of JO201, we find that it is moving through the dense intracluster medium of Abell 85 at supersonic speeds along our line of sight, and that it is likely accompanied by a small group of galaxies. Given the density of the intracluster medium and the galaxy's mass, projected position, and velocity within the cluster, we estimate that JO201 must so far have lost ∼50% of its gas during infall via RPS. The MUSE data indeed reveal a smooth stellar disk accompanied by large projected tails of ionized ( ) gas, composed of kinematically cold (velocity dispersion <40 km s−1) star-forming knots and very warm (>100 km s−1) diffuse emission, that extend out to at least from the galaxy center. The ionized -emitting gas in the disk rotates with the stars out to ∼6 kpc; but, in the disk outskirts, it becomes increasingly redshifted with respect to the (undisturbed) stellar disk. The observed disturbances are consistent with the presence of gas trailing behind the stellar component resulting from intense face-on RPS along the line of sight. Our kinematic analysis is consistent with the estimated fraction of lost gas and reveals that stripping of the disk happens outside-in, causing shock heating and gas compression in the stripped tails.
GAs Stripping Phenomena in galaxies with MUSE (GASP) is a new integral-field spectroscopic survey with MUSE at the VLT aimed at studying gas removal processes in galaxies. We present an overview of ...the survey and show a first example of a galaxy undergoing strong gas stripping. GASP is obtaining deep MUSE data for 114 galaxies at z = 0.04-0.07 with stellar masses in the range in different environments (galaxy clusters and groups over more than four orders of magnitude in halo mass). GASP targets galaxies with optical signatures of unilateral debris or tails reminiscent of gas-stripping processes ("jellyfish galaxies"), as well as a control sample of disk galaxies with no morphological anomalies. GASP is the only existing integral field unit (IFU) survey covering both the main galaxy body and the outskirts and surroundings, where the IFU data can reveal the presence and origin of the outer gas. To demonstrate GASP's ability to probe the physics of gas and stars, we show the complete analysis of a textbook case of a jellyfish galaxy, JO206. This is a massive galaxy ( ) in a low-mass cluster ( ) at a small projected clustercentric radius and a high relative velocity, with ≥90 kpc long tentacles of ionized gas stripped away by ram pressure. We present the spatially resolved kinematics and physical properties of the gas and stars and depict the evolutionary history of this galaxy.
The formation mechanism of tidal dwarf galaxies means they are expected to contain little or no dark matter. As such, they might be expected to be very sensitive to their environment. We investigate ...the impact of ram pressure on tidal dwarf galaxies in a parameter study, varying dwarf galaxy properties and ram pressures. We submit model tidal dwarf galaxies to wind-tunnel style tests using a toy ram pressure model. The effects of ram pressure are found to be substantial, resulting in stellar losses. If tidal dwarf galaxies have their gas stripped, they may be completely destroyed. Ram pressure drag causes acceleration of our dwarf galaxy models, and this further enhances stellar losses. The dragging can also cause stars to lie in a low surface brightness stellar stream that points in the opposite direction to the stripped gas, in a manner distinctive from tidal streams. We investigate the effects of ram pressure on surface density profiles, the dynamics of the stars, and discuss the consequences for dynamical mass measurements.
Merger relics of cluster galaxies Yi, S. K.; Lee, J.; Jung, I. ...
Astronomy and astrophysics (Berlin),
06/2013, Letnik:
554
Journal Article
Recenzirano
Odprti dostop
Context. Sheen and collaborators recently found that a surprisingly large portion (38%) of massive early-type galaxies in heavy clusters show strong merger-related disturbed features. This ...contradicts the general understanding that massive clusters are hostile environments for galaxy mergers. Considering the significance of mergers in galaxy evolution, it is important to understand this. Aims. We aim to present a theoretical foundation that explains galaxy mergers in massive clusters. Methods. We used the N-body simulation technique to perform a cosmological-volume simulation and derive dark-halo merger trees. Then, we used the semi-analytic modeling technique to populate each halo with galaxies. We ran hydrodynamic simulations of galaxy mergers to estimate the lifetime of merger features for the imaging condition used by Sheen and collaborators. We applied this merger feature lifetime to our semi-analytic models. Finally, we counted the massive early-type galaxies in heavy model clusters that would show strong merger features. Results. While there still are substantial uncertainties, our preliminary results are remarkably close to the observed fraction of galaxies with merger features. Key ingredients for the success are twofold: firstly, the subhalo motion in dark haloes has been accurately traced, and, second, the lifetime of merger features has been properly estimated. As a result, merger features are expected to last very long in cluster environments. Many massive early-type galaxies in heavy clusters therefore show merger features not because they experience mergers in the current clusters in situ, but because they still carry their merger features from their previous halo environments. Conclusions. Investigating the merger relics of cluster galaxies is potentially important, because it uniquely allows us to backtrack the halo merger history.
We present the results of a spectroscopic analysis of extremely strong damped Ly
α
absorbers (ESDLAs; log
N
(H
I
) ≳ 21.7) observed with the medium resolution spectrograph, X-shooter at the Very ...Large Telescope (VLT). Recent studies in the literature indicate that ESDLAs probe gas from within the star-forming disk of the associated galaxies and thus ESDLAs provide a unique opportunity to study the interstellar medium of galaxies at high redshift. We report column densities (
N
), equivalent widths (
w
, for Mg
II
and Ca
II
transitions), and the kinematic spread (Δ
v
90
) of species from neutral (namely O
I
, Ar
I
, Cl
I
, N
I
, and Na
I
), singly ionised (Mg
II
, Ca
II
, S
II
, Ni
II
, Mn
II
, Ti
II
, and P
II
), and higher ionisation (C
IV
, Si
IV
, N
V
, and O
VI
) species. We estimate the dust-corrected metallicity measured using different singly ionised gas species such as P
II
, S
II
, Si
II
, Mn
II
and Cr
II
, and Zn
II
. We find that, using the dust correction prescription, the measured metallicities are consistent for all mentioned species in all ESDLAs within 3
σ
uncertainty. We further perform a quantitative comparison of column densities, equivalent widths, and kinematic spreads of ESDLAs with other samples that are associated with galaxies and detected in absorption along the line of sight towards high-redshift quasars (QSOs). We find that the distributions of the Ar
I
to H
I
column density ratio (
N
(Ar
I
)/
N
(H
I
)) in DLAs and ESDLAs are similar. We further report that ESDLAs do not show a strong deficiency of Ar
I
relative to other
α
-capture elements as is seen in DLAs. This supports the idea that the mentioned under-abundance of Ar
I
in DLAs is possibly caused by the presence of background UV photons that penetrate the low
N
(H
I
) clouds to ionise Ar
I
, but they cannot penetrate deep enough in the high
N
(H
I
) ESDLA environment. The
w
(Mg
II
λ
2796) distribution in ESDLAs is found to be similar to that of metal-rich C
I
-selected absorbers, but the velocity spread of their Mg
II
profile is different. The dust content (measured by modelling the quasar extinction) and
w
(Ca
II
λ
3934) distributions are similar in ESDLAs and Ca
II
-selected absorbers, yet we do not see any correlation between
w
(Ca
II
λ
3934) and dust content. The Δ
v
90
velocity spread of singly ionised species in ESDLAs is statistically smaller than that of DLAs. For higher ionisation species (such as C
IV
and Si
IV
) that trace the warm ionised medium, Δ
v
90
is similar in the two populations. This suggests that the ESDLAs sample a different H
I
region of their associated galaxy compared to the general DLA population. We further study the
N
(Cl
I
) distribution in high-redshift DLA and ESDLA sightlines, as Cl
I
is a good tracer of H
2
gas. The
N
(Cl
I
)−
N
(H
2
) correlation is followed by all the clouds (ESDLAs and otherwise) having log
N
(H
2
) < 22.
The gene CDC73 (previously known as HRPT2) encodes the protein parafibromin. Biallelic mutation of CDC73 is strongly associated with malignancy in parathyroid tumors. Heterozygous germline mutations ...cause hyperparathyroidism jaw tumor syndrome,which is associated with a high life-time risk of parathyroid carcinoma. Therefore loss of parafibromin expression by immunohistochemistry may triage genetic testing for hyperparathyroidism jaw tumor syndrome and be associated with malignant behavior in atypical parathyroid tumors. We share our experience that parafibromin-negative parathyroid tumors show distinctive morphology. We searched our institutional database for parathyroid tumors demonstrating complete loss of nuclear expression of parafibromin with internal positive controls. Forty-three parafibromin-negative tumors from 40 (5.1%) of 789 patients undergoing immunohistochemistry were identified. Thirty-three (77%) were external consultation cases; the estimated incidence in unselected tumors was 0.19%. Sixteen (37.2%) fulfilled World Health Organization 2017 criteria for parathyroid carcinoma and 63% had serum calcium greater than 3mmol/L. One of 27 (3.7%) noninvasive but parafibromin-negative tumors subsequently metastasized. Parafibromin-negative patients were younger (mean, 36 vs. 63 y; P<0.001) and had larger tumors (mean, 3.04 vs. 0.62 g; P<0.001). Not all patients had full testing, but 26 patients had pathogenic CDC73 mutation/deletions confirmed in tumor (n=23) and/or germline (n=16). Parafibromin-negative tumors demonstrated distinctive morphology including extensive sheet-like rather than acinar growth, eosinophilic cytoplasm, nuclear enlargement with distinctive coarse chromatin, perinuclear cytoplasmic clearing, a prominent arborizing vasculature, and, frequently, a thick capsule. Microcystic change was found in 21 (48.8%). In conclusion, there are previously unrecognized morphologic clues to parafibromin loss/CDC73 mutation in parathyroid tumors which, given the association with malignancy and syndromic disease, are important to recognize.
We present the GALEX UV photometry of the elliptical galaxies in Abell clusters at moderate redshifts (z < 0.2) for the study of the look-back time evolution of the UV upturn phenomenon. The ...brightest elliptical galaxies (M sub(r) unk -22) in 12 remote clusters are compared with the nearby giant elliptical galaxies of comparable optical luminosity in the Fornax and Virgo clusters. The sample galaxies presented here appear to be quiescent without signs of massive star formation or strong nuclear activity and show smooth, extended profiles in their UV images, indicating that the far-UV (FUV) light is mostly produced by hot stars in the underlying old stellar population. Compared to their counterparts in nearby clusters, the FUV flux of cluster giant elliptical galaxies at moderate redshifts fades rapidly with similar to 2 Gyr of look-back time, and the observed pace in FUV - V color evolution agrees reasonably well with the prediction from the population synthesis models where the dominant FUV source is hot horizontal-branch stars and their progeny. A similar amount of color spread ( similar to 1 mag) in FUV - V exists among the brightest cluster elliptical galaxies at z similar to 0.1, as observed among the nearby giant elliptical galaxies of comparable optical luminosity.
Eleven referring hospitals in South Korea.
To classify the phenotypes in elderly subjects with obstructive lung disease (OLD).
We analysed 191 subjects aged ≥ 60 years with chronic respiratory ...symptoms and either obstructive spirometry or bronchial hyperresponsiveness. Factor analysis was performed using commonly measured variables and revealed four significant variables: 1) the ratio of inspiratory capacity to total lung capacity, 2) the total score on the St George's Respiratory Questionnaire, 3) the volume fraction of the lung less than 950 Hounsfield Unit at full inspiration on volumetric computed tomography and 4) post-bronchodilator forced expiratory volume in 1 second (FEV(1)) changes. We performed a cluster analysis on these four variables.
The mean age was 68.5 (± 5.2 SD) years and the mean post-bronchodilator FEV(1) was 52.4% (± 16.5) predicted. Three clusters with the following phenotypes were identified: Cluster 1 included subjects with moderate to severe airflow obstruction and bronchodilator reversibility; Cluster 2 subjects had moderate airflow obstruction without bronchodilator reversibility, and Cluster 3 subjects had severe airflow obstruction without bronchodilator reversibility.
We identified three phenotypes in elderly subjects with OLD. Follow-up studies are needed to explore the clinical significance of each phenotype.
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