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The quark matter may have great implications in astrophysical studies, which could appear in the early Universe, in compact stars, and/or as cosmic rays. After a general review of astrophysical quark matter, the density-dominated quark matter is focused.
The ROSAT X-ray source 1RXS J114003.0+124112 was identified as a starburst galaxy at redshift 0.177 by He et al. (2001). Meanwhile, the authors also noted that the source is almost two orders of magnitude brighter in X-ray than the X-ray-brightest starburst galaxy and it seems to be in a merging system, making this source an enigmatic system for further observations. This paper reports the re-identification of 1RXS J114003.0+124112 with the observations on the 2.6 m telescope at Byurakan Astrophysical Observatory, Armenia and with the SDSS data. The results indicate that the starburst activity is associated with the brighter object in the system, while the fainter object is a typical Seyfert 1 galaxy at redshift 0.282. Therefore, the two objects are not in a merging system, and the Seyfert 1 galaxy naturally accounts for the high X-ray flux. Three more objects reside in the vicinity, but they are all too faint to be responsible for the high X-ray flux.
A systematical study on the early X-ray afterglows of both optically bright and dark gamma-ray bursts (B-GRBs and D-GRBs) observed by Swift has been presented. Our sample includes 25 GRBs. Among them 13 are B-GRBs and 12 are D-GRBs. Our results show that the distributions of the X-ray afterglow fluxes ($F_{X}$), the gamma-ray fluxes ($S_γ$), and the ratio ($R_{γ, X}$) for both the D-GRBs and B-GRBs are similar. The differences of these distributions for the two kinds of GRBs should be statistical fluctuation. These results indicate that the progenitors of the two kinds of GRBs are the same population. Their total energy explosions are comparable. The suppression of the optical emissions from D-GRBs should results from circumburst but not their central engine.
Some nonlinear dynamical techniques, including state-space reconstruction and correlation integral, are used to analyze the light curve of 3C 273. The result is compared with a chaotic model. The similarity between them suggests that there is a low-dimensional chaotic attractor in the light curve of 3C 273.
We determine relative stellar ages and metallicities mainly for about 80 elliptical galaxies in low and high density environments via the latest binary stellar population (BSP) synthesis model and test a latest hierarchical formation model of elliptical galaxies which adopted the new $Λ$CDM cosmology for the first time. The stellar ages and metallicities of galaxies are estimated from two high-quality published spectra line indices, i.e. H$β$ and [MgFe]. The results show that elliptical galaxies have stellar populations older than 3.9 Gyr and more metal rich than 0.02. Most of our results are in agreement with predictions of the model: First, elliptical galaxies in denser environment are redder and have older populations than field galaxies. Second, elliptical galaxies with more massive stellar components are redder while have older and more metal rich populations than less massive ones. Third, the most massive galaxies are shown to have the oldest and most metal rich stars. However, some of our results are found to be different with predictions of the galaxy formation model, i.e. the metallicity distributions of low- and high-density elliptical galaxies and the relations relating to cluster-centric distance.
A list of questions regarding Gamma Ray Bursts (GRBs) and Soft Gamma Repeaters (SGRs) remain unanswered within the Fireball-cone and Magnetar explosive scenarios. A persistent, thin (less than micron-sr solid angle) precessing and spinning gamma jet, with a power output comparable to the progenitor supernova (SN) or XRay pulsar, may explain these issues. The precessing jets may have a few hours characteristic decay time, while their decreasing intensity follow a power law for thousands of years. The orientation of the spinning and precessing beam respect to the line of sight plays a key role : the farthest GRB events in widest cosmic volumes correspond generally to a very narrow and on-axis beam, while for the nearest ones sources are mostly observable off-axis. Consequentely the far ones are the hardest and the most bright and viceversa nearest one are mostly softer and longest ones as in Amati correlation. We expect that nearby off-axis GRBs would be accompanied by a chain of OT and radio bumps as in GRB030329-SN2003 and latest GRB060218-SN2006 events. Delayed blazing jets are observable in the local universe as X-Ray Flahes (XRFs) or short GRBs often as orphan afterglow event, and at closer distances as SGRs and anomalous X-ray Pulsars AXRPs. The gamma jet is originated by ultra-relativistic electron pairs showering via Synchrotron (or Inverse Compton) radiation. The electron pairs escape from the inner SN core thanks to a more penetrating couriers, the relativistic PeV muon pairs, themselves secondaries of inner UHE hadron jets. They are 'transparent' through the SN shells of matter and lights; they decay far away in to electron pairs (and later on) in gamma and neutrinos jets. Then GRBs (and SGRs) are not the most explosive event of the Universe, but just the most beamed ones.
Formation of giant radio pulses is attributed to propagation effects in the plasma of pulsar magnetosphere. Induced scattering of radio waves by the plasma particles is found to lead to an efficient redistribution of the radio emission in frequency. With the steep spectrum of pulsar radiation, intensity transfer between the widely spaced frequencies may imply significant narrow-band amplification of the radiation. This may give rise to giant pulses. It is demonstrated that the statistics of giant pulse intensities observed can be reproduced if one take into account pulse-to-pulse fluctuations of the plasma number density and the original intensity. Polarization properties of the strongly amplified pulses, their location in the average pulse window and the origin of the nanostructure of giant pulses are discussed as well.
{\it Chandra} Galactic Center Survey detected $\sim 800$ X-ray point-like sources in the $2^{\circ} \times 0.8^{\circ}$ sky region around the Galactic Center. In this paper, we study the spatial and luminosity distributions of these sources according to their spectral properties. Fourteen bright sources detected are used to fit jointly an absorbed power-law model, from which the power-law photon index is determined to be $\sim$2.5. Assuming that all other sources have the same power-law form, the relation between hardness ratio and HI column density $N_H$ is used to estimate the $N_H$ values for all sources. Monte Carlo simulations show that these sources are more likely concentrated in the Galactic center region, rather than distributed throughout the Galactic disk. We also find that the luminosities of the sources are positively correlated with their HI column densities, i.e. a more luminous source has a higher HI column density. From this relation, we suggest that the X-ray luminosity comes from the interaction between an isolated old neutron star and interstellar medium (mainly dense molecular clouds). Using the standard Bondi accretion theory and the statistical information of molecular clouds in the Galactic center, we confirm this positive correlation and calculate the luminosity range in this scenario, which is consistent with the observation ($10^{32}\sim 10^{35}$ ergs s$^{-1}$).
We report the discovery and spectroscopic confirmation of three gravitationally-lensed images of a galaxy at z=3.9 in the background of a distant, rich cluster of galaxies at z=0.83, on the basis of observations with Faint Object Camera And Spectrograph (FOCAS) on the Subaru telescope. We construct a simple lens model of the cluster mass distribution based on Jee et al.'s weak lensing mass estimates from deep, high-resolution images by Advanced Camera for Surveys (ACS) on the Hubble Space Telescope. The lens model can account simultaneously for the observed image configuration and the flux ratio of the closer pair located close to the critical curve. The parities of the three images are also consistent with the lensing hypothesis. Since this galaxy is apparently bright (i'_{AB} \sim 23.7) for its redshift due to the magnification, it serves as a good high redshift target on which we can make extensive and detailed studies based on multi-wavelength imaging and spectroscopy.
To first order in the deviation from scale invariance the inflationary potential and its first two derivatives can be expressed in terms of the spectral indices of the scalar and tensor perturbations, $n$ and $n_T$, and their contributions to the variance of the quadrupole CBR temperature anisotropy, $S$ and $T$. In addition, there is a ``consistency relation'' between these quantities: $n_T= -{1\over 7}{T\over S}$. We discuss the overall strategy of perturbative reconstruction and derive the second-order expressions for the inflationary potential and its first two derivatives and the first-order expression for its third derivative, all in terms of $n$, $n_T$, $S$, $T$, and $dn/d\ln k$. We also obtain the second-order consistency relation, $n_T =-{1\over 7}{T\over S}[1+0.11{T\over S} + 0.15 (n-1)]$. As an example we consider the exponential potential, the only known case where exact analytic solutions for the perturbation spectra exist. We reconstruct the potential via Taylor expansion (with coefficients calculated at both first and second order), and introduce the Padé approximant as a greatly improved alternative.
The AdS/CFT correspondence allows us to map a dynamical cosmology to a dual quantum field theory living on the boundary of spacetime. Specifically, we study a five-dimensional model cosmology in type IIB supergravity, where the dual theory is an unstable deformation of $\N=4$ supersymmetric SU(N) gauge theory on $\Rbar\times S^3$. A one-loop computation shows that the coupling governing the instability is asymptotically free, so quantum corrections cannot turn the potential around. The big crunch singularity in the bulk occurs when a boundary scalar field runs to infinity, in finite time. Consistent quantum evolution requires that we impose boundary conditions at infinite scalar field, i.e. a self-adjoint extension of the system. We find that quantum spreading of the homogeneous mode of the boundary scalar leads to a natural UV cutoff in particle production as the wavefunction for the homogeneous mode bounces back from infinity. However a perturbative calculation indicates that despite this, the logarithmic running of the boundary coupling governing the instability generally leads to significant particle production across the bounce. This prevents the wave packet of the homogeneous boundary scalar to return close to its initial form. Translating back to the bulk theory, we conclude that a quantum transition from a big crunch to a big bang is an improbable outcome of cosmological evolution in this class of five-dimensional models.
Recent results from BOOMERANG-98 and MAXIMA-1, taken together with COBE-DMR, provide consistent and high signal-to-noise measurements of the CMB power spectrum at spherical harmonic multipole bands over $2<\ell\lta800$. Analysis of the combined data yields 68% (95%) confidence limits on the total density, $Ω_{\rm {tot}}\simeq 1.11 \pm 0.07 (^{+0.13}_{-0.12})$, the baryon density, $Ω_b h^2\simeq 0.032^{+0.005}_{-0.004} (^{+0.009}_{-0.008})$, and the scalar spectral tilt, $n_s\simeq1.01^{+0.09}_{-0.07} (^{+0.17}_{-0.14})$. These data are consistent with inflationary initial conditions for structure formation. Taken together with other cosmological observations, they imply the existence of both non-baryonic dark matter and dark energy in the universe.
The shining of quasars is a likely trigger of massive galatic winds, able to remove most ISM from a star-forming spheroid. However, the mechanism responsible for the deposition of energy into the ISM is still unclear. Starting from a model for feedback in galaxy formation with a two-phase medium (Monaco 2004a), we propose that the perturbation induced by radiative heating from a quasar on the ISM triggers a critical change of feedback regime. In the feedback model, SNRs expanding in the hot and pressurized phase of a star-forming spheroid tipically become pressure-confined before the hot interior gas is able to cool. Whenever the evaporation flow due to radiative heating of the quasar is significant with respect to the star-formation rate, the SNRs reach the point where their interior gas cools before being confined, forming a thick cold shell. We show that in this conditions the shells percolate into a super-shell of cold gas that sweeps the whole galaxy. Radiation pressure then pushes the shell out of the galaxy. This self-limiting mechanism leads to a correlation between black hole and bulge masses. The insertion of a motivated wind trigger criterion in a hierarchical galaxy formation model shows however that winds are not necessary to obtain a good black hole--bulge correlation. In absence of winds, good results are obtained if the mechanism responsible for the creation of a reservoir of low-angular momentum gas (able to accrete onto the black hole) deposits mass at a rate proportional to the star-formation rate. Using a novel galaxy formation model, we show under which conditions black hole masses are self-limited by the wind mechanism described above, and outline the possible observational consequences of this self-limitation. [Abridged]
We investigate the structural, kinematical, and spectrophotometric properties of ``E+A'' galaxies -- those with strong Balmer absorption lines but no significant [OII] emission -- using numerical simulations combined with stellar population synthesis codes. We particularly focus on the two-dimensional (2D) distributions of line-of-sight velocity, velocity dispersion, colors, line index in E+A galaxies formed via the interaction and merging of two gas-rich spirals. Our numerical simulations demonstrate that E+A elliptical galaxies formed by major galaxy merging have positive radial color gradients and negative radial H$δ$ gradients by virtue of their central poststarburst populations. Furthermore, we show that the projected kinematical and spectroscopic properties of the simulated E+A galaxies can be remarkably different for different major merger models. For example, the simulated E+A ellipticals with kinematically decoupled cores clearly show regions of strong H$δ$ absorption which are very flattened, with differences in rotation and velocity dispersion between the old and young stars. E+A ellipticals are highly likely to show more rapid rotation and a smaller central velocity dispersion in young stars than in old ones.We also provide specific predictions on the structural, kinematical, and spectrophotometric properties of young globular cluster systems in E+A's. Based on these results, we discuss the importance of spatially resolved, integral field unit spectroscopy on large (8-10m) ground-based telescopes in confirming the formation of kinematically distinct cores in elliptical galaxies produced via dissipative merging and determining the most probable physical mechanism(s) for E+A formation with disky and spheroidal morphologies.
We investigate the angular two-point correlation function of temperature in the WMAP maps. Updating and extending earlier results, we confirm the lack of correlations outside the Galaxy on angular scales greater than about 60 degrees at a level that would occur in 0.025 per cent of realizations of the concordance model. This represents a dramatic increase in significance from the original observations by the COBE-DMR and a marked increase in significance from the first-year WMAP maps. Given the rest of the reported angular power spectrum C_\ell, the lack of large-angle correlations that one infers outside the plane of the Galaxy requires covariance among the C_\ell up to \ell=5. Alternately, it requires both the unusually small (5 per cent of realizations) full-sky large-angle correlations, and an unusual coincidence of alignment of the Galaxy with the pattern of cosmological fluctuations (less than 2 per cent of those 5 per cent). We argue that unless there is some undiscovered systematic error in their collection or reduction, the data point towards a violation of statistical isotropy. The near-vanishing of the large-angle correlations in the cut-sky maps, together with their disagreement with results inferred from full-sky maps, remain open problems, and are very difficult to understand within the concordance model.
We study the observational constraints of CMB temperature and polarization anisotropies on models of dark energy, with special focus on models with variation in properties of dark energy with time. We demonstrate that the key constraint from CMB observations arises from the location of acoustic peaks. An additional constraint arises from the limits on Omega_nr from the relative amplitudes of acoustic peaks. Further, we show that the distance to the last scattering surface is not how the CMB observations constrain the combination of parameters for models of dark energy. We also use constraints from Supernova observations and show that unlike the Gold and Silver samples, the SNLS sample prefers a region of parameter space that has a significant overlap with the region preferred by the CMB observations. This is a verification of a conjecture made by us in an earlier work. We discuss combined constraints from WMAP5 and SNLS observations. We find that models with w ~ -1 are preferred for models with a constant equation of state parameters. In case of models with a time varying dark energy, we show that constraints on evolution of dark energy density are almost independent of the type of variation assumed for the equation of state parameter. This makes it easy to get approximate constraints from CMB observations on arbitrary models of dark energy. Constraints on models with a time varying dark energy are predominantly due to CMB observations, with Supernova constraints playing only a marginal role.
We present results of the detailed Monte Carlo calculation of the rates of double-bang events in 1 km$^3$ underwater neutrino telescope with taking into account the effects of $τ$-neutrino propagation through the Earth. As an input, the moderately optimistic theoretical predictions for diffuse neutrino spectra of AGN jets are used.
The main aim of this paper is to extend the early approach to quantum cosmogenesis provided by Fomin. His approach was developed independently to the well-known Tryon description of the creation of the closed universe as a process of quantum fluctuation of vacuum. We apply the Fomin concept to derive the cosmological observables. We argue that Fomin's idea from his 1973 work, in contrast to Tryon's one has impact on the current Universe models and the proposed extension of his theory now can be tested by distant supernovae SNIa. Fomin's idea of the creation of the Universe is based on the intersection of two fundamental theories: general relativity and quantum field theory with the contemporary cosmological models with dark energy. As a result of comparison with contemporary approaches concerning dark energy, we found out that Fomin's idea appears in the context of the present acceleration of the Universe explanation: cosmological models with decaying vacuum. Contemporary it appears in the form of Ricci scalar dark energy connected with the holographic principle. We show also that the Fomin model admits the bounce instead of the initial singularity. We demonstrate that the Fomin model of cosmogenesis can be falsified and using SNIa data the values of model parameters is in agreement with observations.