1,725 research outputs found
Hubble Space Telescope Weak-lensing Study of the Galaxy Cluster XMMU J2235.3-2557 at z=1.4: A Surprisingly Massive Galaxy Cluster when the Universe is One-third of its Current Age
We present a weak-lensing analysis of the z=1.4 galaxy cluster XMMU
J2235.3-2557, based on deep Advanced Camera for Surveys images. Despite the
observational challenge set by the high redshift of the lens, we detect a
substantial lensing signal at the >~ 8 sigma level. This clear detection is
enabled in part by the high mass of the cluster, which is verified by our both
parametric and non-parametric estimation of the cluster mass. Assuming that the
cluster follows a Navarro-Frenk-White mass profile, we estimate that the
projected mass of the cluster within r=1 Mpc is (8.5+-1.7) x 10^14 solar mass,
where the error bar includes the statistical uncertainty of the shear profile,
the effect of possible interloping background structures, the scatter in
concentration parameter, and the error in our estimation of the mean redshift
of the background galaxies. The high X-ray temperature 8.6_{-1.2}^{+1.3} keV of
the cluster recently measured with Chandra is consistent with this high lensing
mass. When we adopt the 1-sigma lower limit as a mass threshold and use the
cosmological parameters favored by the Wilkinson Microwave Anisotropy Probe
5-year (WMAP5) result, the expected number of similarly massive clusters at z
>~ 1.4 in the 11 square degree survey is N ~ 0.005. Therefore, the discovery of
the cluster within the survey volume is a rare event with a probability < 1%,
and may open new scenarios in our current understanding of cluster formation
within the standard cosmological model.Comment: Accepted to ApJ for publication. 40 pages and 14 figure
Biochemical changes in cotton plants by Arbuscular Mycorrhizal colonization
Biochemical changes in ten cultivars of cotton (Gossypium hirsutum L. Merr. ) in relation with arbuscular mycorrhizal (AM) colonization was studied.ĂâĂ Proteins, sugars, amino acids and phenols in both leaves and roots were quantified and compared with the mycorrhization levels of the cultivars. Cultivars showed varying levels of mycorrization which correlated with the biochemical levels of the plants. It is concluded that cultivars which are more mycorrhizal do show increased levels of phenols and proteins which in turn help them to resist pathogenesis
Muscle plasticity related to changes in tubulin and αB-crystallin levels induced by eccentric contraction in rat skeletal muscles
We used the model of eccentric contraction of the hindlimb muscle by Ochi et al. to examine the role of eccentric contraction in muscle plasticity. This model aims to focus on stimulated skeletal muscle responses by measuring tissue weights and tracing the quantities of αB-crystallin and tubulin. The medial gastrocnemius muscle (GCM) responded to electrically induced eccentric contraction (EIEC) with significant increases in tissue weight (pâ<â0.01) and the ratio of tissue weight to body weight (pâ<â0.05); however, there was a decrease in soleus muscle weight after EIEC. EIEC in the GCM caused contractile-induced sustenance of the traced proteins, but the soleus muscle exhibited a remarkable decrease in α-tubulin and a 19% decrease in αB-crystallin. EIEC caused fast-to-slow myosin heavy chain (MHC) isoform type-oriented shift within both the GCM and soleus muscle. These results have shown that different MHC isoform type-expressing slow and fast muscles commonly undergo fast-to-slow type MHC isoform transformation. This suggests that different levels of EIEC affected each of the slow and fast muscles to induce different quantitative changes in the expression of αB-crystallin and α-tubulin
Scaling Relations and Overabundance of Massive Clusters at z>~1 from Weak-Lensing Studies with HST
We present weak gravitational lensing analysis of 22 high-redshift (z >~1)
clusters based on Hubble Space Telescope images. Most clusters in our sample
provide significant lensing signals and are well detected in their
reconstructed two-dimensional mass maps. Combining the current results and our
previous weak-lensing studies of five other high-z clusters, we compare
gravitational lensing masses of these clusters with other observables. We
revisit the question whether the presence of the most massive clusters in our
sample is in tension with the current LambdaCDM structure formation paradigm.
We find that the lensing masses are tightly correlated with the gas
temperatures and establish, for the first time, the lensing mass-temperature
relation at z >~ 1. For the power law slope of the M-TX relation (M propto
T^{\alpha}), we obtain \alpha=1.54 +/- 0.23. This is consistent with the
theoretical self-similar prediction \alpha=3/2 and with the results previously
reported in the literature for much lower redshift samples. However, our
normalization is lower than the previous results by 20-30%, indicating that the
normalization in the M-TX relation might evolve. After correcting for Eddington
bias and updating the discovery area with a more conservative choice, we find
that the existence of the most massive clusters in our sample still provides a
tension with the current Lambda CDM model. The combined probability of finding
the four most massive clusters in this sample after marginalization over
current cosmological parameters is less than 1%.Comment: ApJ in press. See http://www.supernova.lbl.gov for additional
information pertaining to the HST Cluster SN Surve
The Hubble Constant determined through an inverse distance ladder including quasar time delays and Type Ia supernovae
Context. The precise determination of the present-day expansion rate of the
Universe, expressed through the Hubble constant , is one of the most
pressing challenges in modern cosmology. Assuming flat CDM,
inference at high redshift using cosmic-microwave-background data from Planck
disagrees at the 4.4 level with measurements based on the local
distance ladder made up of parallaxes, Cepheids and Type Ia supernovae (SNe
Ia), often referred to as "Hubble tension". Independent,
cosmological-model-insensitive ways to infer are of critical importance.
Aims. We apply an inverse-distance-ladder approach, combining strong-lensing
time-delay-distance measurements with SN Ia data. By themselves, SNe Ia are
merely good relative distance indicators, but by anchoring them to strong
gravitational lenses one can obtain an measurement that is relatively
insensitive to other cosmological parameters. Methods. A cosmological parameter
estimate is performed for different cosmological background models, both for
strong-lensing data alone and for the combined lensing + SNe Ia data sets.
Results. The cosmological-model dependence of strong-lensing measurements
is significantly mitigated through the inverse distance ladder. In combination
with SN Ia data, the inferred consistently lies around 73-74 km s
Mpc, regardless of the assumed cosmological background model. Our
results agree nicely with those from the local distance ladder, but there is a
>2 tension with Planck results, and a ~1.5 discrepancy with
results from an inverse distance ladder including Planck, Baryon Acoustic
Oscillations and SNe Ia. Future strong-lensing distance measurements will
reduce the uncertainties in from our inverse distance ladder.Comment: 5 pages, 3 figures, A&A letters accepted versio
Relative dosimetry using active matrix flatĂą panel imager (AMFPI) technology
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135008/1/mp8649.pd
HST/Acs Weak-Lensing and Chandra X-Ray Studies of the High-Redshift Cluster MS 1054-0321
We present Hubble Space Telescope/Advanced Camera for Surveys (ACS)
weak-lensing and Chandra X-ray analyses of MS 1054-0321 at z=0.83, the most
distant and X-ray luminous cluster in the Einstein Extended Medium-Sensitivity
Survey (EMSS). The high-resolution mass reconstruction through ACS weak-lensing
reveals the complicated dark matter substructure in unprecedented detail,
characterized by the three dominant mass clumps with the four or more minor
satellite groups within the current ACS field. The direct comparison of the
mass map with the Chandra X-ray image shows that the eastern weak-lensing
substructure is not present in the X-ray image and, more interestingly, the two
X-ray peaks are displaced away from the hypothesized merging direction with
respect to the corresponding central and western mass clumps, possibly because
of ram pressure. In addition, as observed in our previous weak-lensing study of
another high-redshift cluster CL 0152-1357 at z=0.84, the two dark matter
clumps of MS 1054-0321 seem to be offset from the galaxy counterparts. We
examine the significance of these offsets and discuss a possible scenario,
wherein the dark matter clumps might be moving ahead of the cluster galaxies.
The non-parametric weak-lensing mass modeling gives a projected mass of M(r<1
Mpc)=(1.02+-0.15)x 10^{15} solar mass, where the uncertainty reflects both the
statistical error and the cosmic shear effects. Our temperature measurement of
T=8.9_{-0.8}^{+1.0} keV utilizing the newest available low-energy quantum
efficiency degradation prescription for the Chandra instrument, together with
the isothermal beta description of the cluster (r_c=16"+-15" and
beta=0.78+-0.08), yields a projected mass of M(r<1 Mpc)=(1.2+-0.2) x 10^{15}
solar mass, consistent with the weak-lensing result.Comment: Accepted for publication in apj. Full-resolution version can be
downloaded from http://acs.pha.jhu.edu/~mkjee/ms1054.pd
The potato rhizosphere microbiota correlated to the yield of three different regions in Korea
We examined potato rhizosphere bacterial and fungal communities across three regions: Cheongju, Pyeongchang, and Gangneung. These regions have varying soil and climate conditions, resulting in different yields. We found that precipitation was the main limiting factor in our study while soil physiochemical factors affect bacterial and fungal microbiota in correlation with yield. Both bacterial and fungal microbiota showed distinct patterns according to the regions. ASVs positively correlated with yield were predominantly found in the Pyeongchang region which also produced the highest yields, while ASVs negatively correlated with yield were associated with Gangneung where the lowest yields were observed. The greatest bacterial and fungal diversity was detected in Pyeongchang consisting of Propionibacteriales, Burkholderiales, and Vicinamibacteriales. Gangneung, on the other hand primarily belong to Sordariales, Mortierellales, Cystofilobasidiales, and Tremellales. The putative yield-negative ASVs detected in Gangneung may have been influenced by drought stress. This work has highlighted key bacterial and fungal taxa as well as core taxa that may potentially be associated with high and low yields of potato in relation to metadata which includes soil chemical and physical parameters as well as weather data. Taken together we suggest that this information can be used to assess site suitability for potato production
Multi-wavelength study of XMMU J2235.3-2557: the most massive galaxy cluster at z > 1
[Abridged] XMMU J2235.3-2557 is one of the most distant X-ray selected
clusters, spectroscopically confirmed at z=1.39. We characterize the galaxy
populations of passive members, the thermodynamical properties of the hot gas,
its metal abundance and the total mass of the system using imaging data with
HST/ACS (i775 and z850 bands) and VLT/ISAAC (J and K_s bands), extensive
spectroscopic data obtained with VLT/FORS2, and deep Chandra observations. Out
of a total sample of 34 spectroscopically confirmed cluster members, we
selected 16 passive galaxies within the central 2' (or 1 Mpc) with ACS
coverage, and inferred star formation histories for a sub-sample of galaxies
inside and outside the core by modeling their spectro-photometric data with
spectral synthesis models, finding a strong mean age radial gradient. Chandra
data show a regular elongated morphology, closely resembling the distribution
of core galaxies, with a significant cool core. We measure a global X-ray
temperature of kT=8.6(-1.2,+1.3) keV (68% c.l.). By detecting the rest-frame
6.7 keV Iron K line, we measure a metallicty Z= 0.26(+0.20,-0.16) Zsun. In the
likely hypothesis of hydrostatic equilibrium, we obtain a total mass of Mtot(<1
Mpc)=(5.9+-1.3)10^14 Msun. Overall, our analysis implies that XMM2235 is the
hottest and most massive bona-fide cluster discovered to date at z>1, with a
baryonic content, both its galaxy population and intra-cluster gas, in a
significantly advanced evolutionary stage at 1/3 of the current age of the
Universe.Comment: 9 pages, 8 figures, accepted for publication in A&A (v2:
typos/language style corrections, updated references
Deep VLA Observations of the Cluster 1RXS J0603.3+4214 in the Frequency Range of 1â2 GHz
We report L-band VLA observations of 1RXS J0603.3+4214, a cluster that hosts
a bright radio relic, known as the Toothbrush, and an elongated giant radio
halo. These new observations allow us to study the surface brightness
distribution down to one arcsec resolution with very high sensitivity. Our
images provide an unprecedented detailed view of the Toothbrush, revealing
enigmatic filamentary structures. To study the spectral index distribution, we
complement our analysis with published LOFAR and GMRT observations. The bright
`brush' of the Toothbrush shows a prominent narrow ridge to its north with a
sharp outer edge. The spectral index at the ridge is in the range
. We suggest that the ridge is caused by projection
along the line of sight. With a simple toy model for the smallest region of the
ridge, we conclude that the magnetic field is below and varies
significantly across the shock front. Our model indicates that the actual Mach
number is higher than that obtained from the injection index and agrees well
with the one derived from the overall spectrum, namely . The radio halo shows an average spectral index of
and a slight gradient from north to south. The
southernmost part of the halo is steeper and possibly related to a shock front.
Excluding the southernmost part, the halo morphology agrees very well with the
X-ray morphology. A power-law correlation is found between the radio and X-ray
surface brightnessComment: 23 pages, 21 figures, accepted for publication in Ap
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