Cluster mergers are the most energetic events, releasing kinetic energies of up to 1064 erg and involving megaparsec(Mpc)-scale shocks in their intra-cluster medium (ICM). In merging clusters, cold ...fronts are frequently observed, which are characterized by temperature and density jumps while maintaining constant pressure. They, together with the overall morphology of the ICM, provide important information for our understanding of the merging structure, such as velocity, impact parameter, and mass. Abell 3667 is a nearby ($z$=0.056) merging cluster with a prominent cold front and a pair of two bright radio relics. Assuming a head-on merger, the origin of the cold front is often considered to be a remnant of the cluster core stripped by its surrounding ICM. Some authors have proposed an offset merger scenario in which the subcluster core rotates after the first core crossing. This scenario can reproduce features such as the cold front and a pair of radio relics. To distinguish between these scenarios, we reanalyzed the ICM distribution and measured the line-of-sight bulk ICM velocity using the XMM- Newton PN data. We created an unsharp masked image to identify ICM features, and analyzed X-ray spectra to explore the ICM thermodynamical state. Applying the new XMM- Newton European Imaging Camera (EPIC)--PN calibration technique using background emission lines, the line-of-sight bulk ICM velocities were also measured. In the unsharp masked image, we identify several ICM features, some of which we detect for the first time. We confirm the cold front and note an enhanced region extending from the cold front to the west (named ``CF-W tail''). There is an enhancement of the X-ray surface brightness extending from the first brightest cluster galaxy (BCG) to the cold front, which is named the ``BCG-E tail''. The notable feature is a ``RG1 vortex'', which is a clockwise vortex-like enhancement with a radius of about 250 kpc connecting the first BCG to the radio galaxy (RG1). It is particularly enhanced near the north of the 1st BCG, which is named the ``BCG-N tail''. The thermodynamic maps show that the ICM of the RG1 vortex has a relatively high abundance of 0.5-0.6 solar compared to the surrounding regions. The ICM of the BCG-E tail also has a high abundance and low pseudo-entropy and can be interpreted as a remnant of the cluster core's ICM. Including its arc-like shape, the RG1 vortex supports the idea that the ICM around the cluster center is rotating, which is natural for an offset merger scenario. The results of the line-of-sight bulk ICM velocity measurements show that the ICM around the BCG-N tail is redshifted with a velocity difference of 940pm 440 km s$^ $ compared to the optical redshift of the first BCG. We obtain other indications of variations in the line-of-sight velocity of the ICM and discuss these in the context of an offset merger.
The photoluminescence (PL) profiles in deep region of ZnTe grown on tilted GaAs (0
0
1) substrates, 2° off toward 〈1
1
0〉, without ZnSe buffer layer have weak self-activated (SA) emissions at about ...1.6–2.0
eV. PL shows the characteristic dependence on the excitation intensity and temperature. The excitation intensity dependence of the PL structure at 2.322
eV shows that the emission structure is due to the donor–acceptor pairs (DAP). The temperature dependence of the DAP emission indicates a two-step thermal quenching process. The zero-phonon line of the phonon replicas of oxygen isoelectronic traps is lowered by 5
meV from that of bulk crystal due to the difference in the thermal expansions between ZnTe and the substrate. The emissions at around 1.65
eV are the SA emissions related to Te-interstitial atoms.
We have grown ZnSe on GaN (0
0
0
1) substrate by MBE. Although the X-ray rocking curve shows that the growth axis of ZnSe is 〈1
1
1〉, the samples show only ZnSe-LO Raman signal in the optical ...arrangement of back-scattering geometry. The photoluminescence (PL) profiles indicate a strong self-activated emission band around 2.1–2.2
eV due to the Zn vacancies. Some structures observed in the PL spectra are due to the resonant Raman scattering corresponding to the LO phonon replica. The PL peaks at 2.85, 2.82 and 2.79
eV are considered to be the Raman signals of 7-, 8- and 9-LO, respectively, from the laser diode 3.06
eV (405
nm) used as the excitation source.
An oxide layer that covers MBE-ZnTe/GaAs has been removed by a very simple hydrogen (H
2) gas treatment. Intentionally oxidized ZnTe/GaAs samples were exposed to H
2 gas cracked using a tungsten ...heater located in a ceramic tube. The gas irradiation unit was inserted into the MBE growth chamber through a K-cell port. The diffused RHEED patterns of the oxidized ZnTe surfaces become spotty after exposure to cracked H
2 gas. H
2 treatment changes the half-width of the oxidized ZnTe X-ray rocking curve to correspond to the as-grown sample. After re-growth of ZnTe onto the treated ZnTe surface, the RHEED patterns changed from spotty to streaky. Elimination of the oxide layer on the ZnTe surface by this method requires a longer time than was the case for ZnSe.
We observed electronic K x rays emitted from muonic iron atoms using superconducting transition-edge sensor microcalorimeters. The energy resolution of 5.2 eV in FWHM allowed us to observe the ...asymmetric broad profile of the electronic characteristic K α and K β x rays together with the hypersatellite Khα x rays around 6 keV. This signature reflects the time-dependent screening of the nuclear charge by the negative muon and the L-shell electrons, accompanied by electron side feeding. Assisted by a simulation, these data clearly reveal the electronic K - and L-shell hole production and their temporal evolution on the 10–20 fs scale during the muon cascade process.
The specially designed ZnSe–ZnTe superlattice (SL), type-II SL, has the light up-conversion effect that SL emits a photoluminescence (PL) peak under the irradiation of the excitation light with the ...lower energy than the PL peak. The excitation intensity dependence of the energy of up-converted PL peak obeys the characteristic of type-II SL. The PL peak intensity has the super-linear dependence on the excitation intensity. The five kinds of samples in this work showed these phenomena. The model to explain these situations has been proposed.
We present the first measurements of the abundances of alpha-elements (Mg, Si, and S) extending out beyond the virial radius of a cluster of galaxies. Our results, based on Suzaku Key Project ...observations of the Virgo Cluster, show that the chemical composition of the intracluster medium is consistent with being constant on large scales, with a flat distribution of the Si/Fe, S/Fe, and Mg/Fe ratios as a function of radius and azimuth out to 1.4 Mpc (1.3 r sub(200)). Chemical enrichment of the intergalactic medium due solely to core-collapse supemovae (SNcc) is excluded with very high significance; instead, the measured metal abundance ratios are generally consistent with the solar value. The uniform metal abundance ratios observed today are likely the result of an early phase of enrichment and mixing, with both SNcc and SNe la contributing to the metal budget during the period of peak star formation activity at redshifts of 2-3. We estimate the ratio between the number of SNe la and the total number of supemovae enriching the intergalactic medium to be between 12% and 37%, broadly consistent with the metal abundance patterns in our own Galaxy or with the SN Ia contribution estimated for the cluster cores.
We present the first measurements of the abundances of α-elements (Mg, Si, and S) extending out beyond the virial radius of a cluster of galaxies. Our results, based on Suzaku Key Project ...observations of the Virgo Cluster, show that the chemical composition of the intracluster medium is consistent with being constant on large scales, with a flat distribution of the Si/Fe, S/Fe, and Mg/Fe ratios as a function of radius and azimuth out to 1.4 Mpc (1.3 r{sub 200}). Chemical enrichment of the intergalactic medium due solely to core-collapse supernovae (SNcc) is excluded with very high significance; instead, the measured metal abundance ratios are generally consistent with the solar value. The uniform metal abundance ratios observed today are likely the result of an early phase of enrichment and mixing, with both SNcc and SNe Ia contributing to the metal budget during the period of peak star formation activity at redshifts of 2–3. We estimate the ratio between the number of SNe Ia and the total number of supernovae enriching the intergalactic medium to be between 12% and 37%, broadly consistent with the metal abundance patterns in our own Galaxy or with the SN Ia contribution estimated for the cluster cores.
The photoluminescence (PL) spectra of the type II ZnSe–ZnTe superlattices with dual-subband structures have two emission peaks. The PL peak at the higher energy side appears by the excitation even ...with the light, with the middle energy between the PL peaks. The emission energy of the up-converted light shows dependence similar to the case of direct excitation (high-energy excitation) on the excitation intensity. The emission energy increases with increase in the excitation intensity. The up-converted and the direct excited emissions are due to the same state in the superlattice.
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