121351952
The infrared spectrum of H-3 + in laboratory and space plasmas
Protonated hydrogen, H 3 + , composed of three protons and two electrons, is the simplest stable polyatomic system. It is the most abundant ionic species in molecular hydrogen plasmas, and it is assumed to play a central role in the chemical evolution of molecular clouds, the birthplace of stars. The existence of this species has been known since its discovery by J.J. Thomson in 1912, but its first spectrum was observed only in 1980. The infrared spectrum has since been extended to higher vibrational and rotational states
9647415
Absorption Line Survey of H3+ toward the Galactic Center Sources. II. Eight Infrared Sources within 30 pc of the Galactic Center*
Infrared absorption lines of H þ , including the metastable R(3;3) l line, have been observed toward eight bright infrared sources associated with hot and massive stars located in and between the Galactic center cluster and the Quintuplet cluster 30 pc to the east. The absorption lines with high-velocity dispersion arise in the Galaxy’s central molecular zone (CMZ) as well as in foreground spiral arms. The temperature and density of the gas in the CMZ, as determined from the relative strengths of the H þ lines, are T ¼ 200Y300 K and n � 50Y200 cm � 3 . The detection of high column densities of H þ toward all eight stars implies that this warm and diffuse gaseous environment is widespread in the CMZ. The products of the ionization rate and path length for these sight lines are 1000 and 10 times higher than in dense and diffuse clouds in the Galactic disk, respectively, indicating that the ionization rate, � , is not less than 10 � 15 s � 1 and that L is at least on the order of 50 pc. The warm and diffuse gas is an important component of theCMZ,inadditiontothethreepreviouslyknowngaseousenvironments:(1)coldmolecularcloudsobservedbyradio emission of CO and other molecules; (2) hot (T ¼ 10 4 Y10 6 K) and highly ionized diffuse gas (ne ¼10Y100 cm � 3 ) seeninradiorecombinationlines,farinfraredatomiclines,andradio-wavescattering;and(3)ultrahot(T ¼10 7 Y10 8 K) X-ray emitting plasma. Its prevalence significantly changes the understanding of the environment of the CMZ. The sight line toward GC IRS 3 is unique in showing an additional H þ absorption component, which is interpreted as being due to either a cloud associated with circumnuclear disk or the ‘‘50 km s � 1 cloud’’ known from radio observations.Aninfraredpumpingschemeisexaminedasamechanismtopopulatethe(3,3)metastablelevelinthiscloud. Subject headingg Galaxy: center — ISM: clouds — ISM: lines and bands — ISM: molecules —
12286403
HOT AND DIFFUSE CLOUDS NEAR THE GALACTIC CENTER PROBED BY METASTABLE H~3^+
Using an absorption line from the metastable (J ; K) ¼ (3; 3) level of H þ together with other lines of H þ and CO observed along several sight lines, we have discovered a vast amount of high-temperature (T � 250 K) and lowdensity (n � 100 cm � 3 ) gas with a large velocity dispersion in the central molecular zone (CMZ) of the Galaxy, i.e., within 200 pc of the center. Approximately three-fourths of the H þ along the line of sight to the brightest source we observed, the Quintuplet object GCS 3-2, is inferred to be in the CMZ, with the remaining H þ located in intervening spiral arms. About half of the H þ in the CMZ has velocities near �� 100 km s � 1 , indicating that it is associated with the 180 pc radius expanding molecular ring, which approximately forms the outer boundary of the CMZ. The other half,withvelocitiesof �� 50and � 0kms � 1 ,isprobablyclosertothecenter.COisnotveryabundantintheseclouds. Hot and diffuse gas in which the (3, 3) level is populated was not detected toward several dense clouds and diffuse clouds intheGalacticdiskwhere largecolumndensities ofcolder H þ have beenreportedpreviously.Thus,thenewly discovered environment appears to be unique to the CMZ. The large observed H þ column densities in the CMZ suggestanionizationratemuchhigher thaninthediffuseinterstellarmediumintheGalacticdisk.Ourfindingthatthe H þ in the CMZ is almost entirely in diffuse clouds indicates that the reported volume filling factor (f � 0:1) for n � 10 4 cm � 3 clouds in the CMZ is an overestimate by at least an order of magnitude. Subject headings: astrochemistry — Galaxy: center — ISM: clouds — ISM: molecules — molecular processes — radiation mechanisms: nonthermal
116986876
Strong field physics in condensed matter
There are deep similarities between non-linear QFT studied in high-energy and non-equilibrium physics in condensed matter. Ideas such as the Schwinger mechanism and the Volkov state are deeply related to non-linear transport and photovoltaic Hall effect in condensed matter. Here, we give a review on these relations.
54072178
Electric field quench in AdS/CFT
A bstractAn electric field quench, a suddenly applied electric field, can induce nontrivial dynamics in confining systems which may lead to thermalization as well as a deconfinement transition. In order to analyze this nonequilibrium transitions, we use the AdS/CFT correspondence for N=2$$ \mathcal{N}=2 $$ supersymmetric QCD that has a confining meson sector. We find that the electric field quench causes the deconfinement transition even when the magnitude of the applied electric field is smaller than the critical value for the static case (which is the QCD Schwinger limit for quark-antiquark pair creation). The time dependence is crucial for this phenomenon, and the gravity dual explains it as an oscillation of a D-brane in the bulk AdS spacetime. Interestingly, the deconfinement time takes only discrete values as a function of the magnitude of the electric field. We advocate that the new deconfinement phenomenon is analogous to the exciton Mott transition.