11,685 research outputs found

    Novel duality in disorder driven local quantum criticality

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    We find that competition between random Kondo and random magnetic correlations results in a quantum phase transition from a local Fermi liquid to a spin liquid. The local charge susceptibility turns out to have exactly the same critical exponent as the local spin susceptibility, suggesting novel duality between the Kondo singlet phase and the critical local moment state beyond the Landau-Ginzburg-Wilson symmetry breaking framework. This leads us to propose an enhanced symmetry at the local quantum critical point, described by an O(4) vector for spin and charge. The symmetry enhancement serves mechanism of electron fractionalization in critical impurity dynamics, where such fractionalized excitations are identified with topological excitations

    Spin liquids in graphene

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    We reveal that local interactions in graphene allow novel spin liquids between the semi-metal and antiferromagnetic Mott insulating phases, identified with algebraic spin liquid and Z2_{2} spin liquid, respectively. We argue that the algebraic spin liquid can be regarded as the two dimensional realization of one dimensional spin dynamics, where antiferromagnetic correlations show exactly the same power-law dependence as valence bond correlations. Nature of the Z2_{2} spin liquid turns out to be d+id′d + i d' singlet pairing, but time reversal symmetry is preserved, taking d+id′d + i d' in one valley and d−id′d - i d' in the other valley. We propose the quantized thermal valley Hall effect as an essential feature of this gapped spin liquid state. Quantum phase transitions among the semi-metal, algebraic spin liquid, and Z2_{2} spin liquid are shown to be continuous while the transition from the Z2_{2} spin liquid to the antiferromagnetic Mott insulator turns out to be the first order. We emphasize that both algebraic spin liquid and d±id′d \pm id' Z2_{2} spin liquid can be verified by the quantum Monte Carlo simulation, showing the enhanced symmetry in the algebraic spin liquid and the quantized thermal valley Hall effect in the Z2_{2} spin liquid

    Chemical pre-processing of cluster galaxies over the past 10 billion years in the IllustrisTNG simulations

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    We use the IllustrisTNG simulations to investigate the evolution of the mass-metallicity relation (MZR) for star-forming cluster galaxies as a function of the formation history of their cluster host. The simulations predict an enhancement in the gas-phase metallicities of star-forming cluster galaxies (10^9< M_star<10^10 M_sun) at z<1.0 in comparisons to field galaxies. This is qualitatively consistent with observations. We find that the metallicity enhancement of cluster galaxies appears prior to their infall into the central cluster potential, indicating for the first time a systematic "chemical pre-processing" signature for {\it infalling} cluster galaxies. Namely, galaxies which will fall into a cluster by z=0 show a ~0.05 dex enhancement in the MZR compared to field galaxies at z<0.5. Based on the inflow rate of gas into cluster galaxies and its metallicity, we identify that the accretion of pre-enriched gas is the key driver of the chemical evolution of such galaxies, particularly in the stellar mass range (10^9< M_star<10^10 M_sun). We see signatures of an environmental dependence of the ambient/inflowing gas metallicity which extends well outside the nominal virial radius of clusters. Our results motivate future observations looking for pre-enrichment signatures in dense environments.Comment: 5 pages, 4 figures, accepted for publication in MNRAS Letter

    Forming Early-type Galaxies in Groups Prior to Cluster Assembly

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    We study a unique proto-cluster of galaxies, the supergroup SG1120-1202. We quantify the degree to which morphological transformation of cluster galaxies occurs prior to cluster assembly in order to explain the observed early-type fractions in galaxy clusters at z=0. SG1120-1202 at z~0.37 is comprised of four gravitationally bound groups that are expected to coalesce into a single cluster by z=0. Using HST ACS observations, we compare the morphological fractions of the supergroup galaxies to those found in a range of environments. We find that the morphological fractions of early-type galaxies (~60 %) and the ratio of S0 to elliptical galaxies (0.5) in SG1120-1202 are very similar to clusters at comparable redshift, consistent with pre-processing in the group environment playing the dominant role in establishing the observed early-type fraction in galaxy clusters.Comment: 5 pages, 2 figures, 2 tables. Accepted for publication in ApJ Letter

    Competition between Kondo and RKKY correlations in the presence of strong randomness

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    We propose that competition between Kondo and magnetic correlations results in a novel universality class for heavy fermion quantum criticality in the presence of strong randomness. Starting from an Anderson lattice model with disorder, we derive an effective local field theory in the dynamical mean-field theory (DMFT) approximation, where randomness is introduced into both hybridization and Ruderman-Kittel-Kasuya-Yosida (RKKY) interactions. Performing the saddle-point analysis in the U(1) slave-boson representation, we reveal its phase diagram which shows a quantum phase transition from a spin liquid state to a local Fermi liquid phase. In contrast with the clean limit of the Anderson lattice model, the effective hybridization given by holon condensation turns out to vanish, resulting from the zero mean value of the hybridization coupling constant. However, we show that the holon density becomes finite when variance of hybridization is sufficiently larger than that of the RKKY coupling, giving rise to the Kondo effect. On the other hand, when the variance of hybridization becomes smaller than that of the RKKY coupling, the Kondo effect disappears, resulting in a fully symmetric paramagnetic state, adiabatically connected with the spin liquid state of the disordered Heisenberg model. .....

    The Outstanding Decisions of the United States Supreme Court in 1954

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    We perform a kinematic and morphological analysis of 44 star-forming galaxies at z ̃ 2 in the COSMOS legacy field using near-infrared spectroscopy from Keck/MOSFIRE and F160W imaging from CANDELS/3D-HST as part of the ZFIRE survey. Our sample consists of cluster and field galaxies from 2.0 &lt; z &lt; 2.5 with K-band multi-object slit spectroscopic measurements of their Hα emission lines. Hα rotational velocities and gas velocity dispersions are measured using the Heidelberg Emission Line Algorithm (HELA), which compares directly to simulated 3D data cubes. Using a suite of simulated emission lines, we determine that HELA reliably recovers input S 0.5 and angular momentum at small offsets, but V 2.2/σ g values are offset and highly scattered. We examine the role of regular and irregular morphology in the stellar mass kinematic scaling relations, deriving the kinematic measurement S 0.5, and finding {log}({S}0.5)=(0.38+/- 0.07){log}(M/{M}☉ -10)+(2.04+/- 0.03) with no significant offset between morphological populations and similar levels of scatter (̃0.16 dex). Additionally, we identify a correlation between M ⋆ and V 2.2/σ g for the total sample, showing an increasing level of rotation dominance with increasing M ⋆, and a high level of scatter for both regular and irregular galaxies. We estimate the specific angular momenta (j disk) of these galaxies and find a slope of 0.36 ± 0.12, shallower than predicted without mass-dependent disk growth, but this result is possibly due to measurement uncertainty at M ⋆ &lt; 9.5 However, through a Kolmogorov-Smirnov test we find irregular galaxies to have marginally higher j disk values than regular galaxies, and high scatter at low masses in both populations

    First Measurement of a Rapid Increase in the AGN Fraction in High-Redshift Clusters of Galaxies

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    We present the first measurement of the AGN fraction in high-redshift clusters of galaxies (z~0.6) with spectroscopy of one cluster and archival data for three additional clusters. We identify 8 AGN in all four of these clusters from the Chandra data, which are sensitive to AGN with hard X-ray (2-10keV) luminosity L_{X,H} > 10^43 erg/s in host galaxies more luminous than a rest frame M_R < -20 mag. This stands in sharp contrast to the one AGN with L_{X,H} > 10^43 erg/s we discovered in our earlier study of eight low-redshift clusters with z=0.06-0.31 (average z~0.2). Three of the four high-redshift cluster datasets are sensitive to nearly L_{X,H} > 10^42 erg/s and we identify seven AGN above this luminosity limit, compared to two in eight, low-redshift clusters. Based on membership estimates for each cluster, we determine that the AGN fraction at z~0.6 is f_A(L_X>10^42;M_R<-20) = 0.028 (+0.019/-0.012) and f_A(L_X>10^43;M_R<-20) = 0.020 (+0.012/-0.008). These values are approximately a factor of 20 greater than the AGN fractions in lower-redshift (average z~0.2) clusters of galaxies and represent a substantial increase over the factors of 1.5 and 3.3 increase, respectively, in the measured space density evolution of the hard X-ray luminosity function over this redshift range. Potential systematic errors would only increase the significance of our result. The cluster AGN fraction increases more rapidly with redshift than the field and the increase in cluster AGN indicates the presence of an AGN Butcher-Oemler Effect.Comment: ApJL Accepted, 5 pages, 2 figure

    Cardiac failure following inadvertent administration of high-dose epinephrine subcutaneously

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    Our aim is to report the consequences of epinephrine toxicity leading to cardiac failure in a child and the successful management with dopamine and milrinone. A previously healthy 13-year-old girl undergoing a left tympanomastoidectomy was inadvertently administered 10 mL of 1:1000 epinephrine subcutaneously (0.175 mg/kg) on the left post auricular region in lieu of lidocaine. She developed sudden supraventricular tachycardia, hypertension and flash pulmonary edema. She was initially treated with propofol, nitrogycerin and increased peak end-expiratory pressure. Within 4 h, she remained tachycardic, but was hypotensive with an increased central venous pressure. Electrocardiogram and echocardiogram investigations showed ST changes indicative of myocardial ischemia and globally reduced function, respectively. Dopamine infusion was administered, together with milrinone, resulting in a gradual improvement of cardiac function within 3 days. She was transitioned to enalapril and discharged home. This case highlights the clinical features of high dose epinephrine toxicity secondary to iatrogenic subcutaneous overdose followed by hypotension and pulmonary edema as a possible late effect of epinephrine and the successful management of secondary cardiac failure with administration of dopamine, milrinone and enalapril. © 2012 - IOS Press and the authors
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