Rydberg Matter as the dust atmosphere in comets: Spectroscopic and polarization signatures

The long-lived excited state of matter called Rydberg Matter (RM) may explain several spectroscopic features in space, like the diffuse interstellar bands (DIBs) and the unidentified infrared bands (UIR, UIB). RM is here used to interpret some previously unexplained or inconsistent features in comets: (1) line absorption in the emission from the nucleus, (2) IR band emission from the coma, (3) selective and variable molecular line emission from the coma, (4) extended sources of molecules in the coma, (5) degree of linear polarization of light scattered from the coma. (1) The unexplained IR absorptions observed in the flyby of the nucleus of the Comet Borrelly agree well with RM emission bands observed by stimulated emission in the laboratory. It is proposed that RM is the so-called ultrared matter or at least formed from it. (2) The IR bands previously attributed to silicate particles are shown to be better described by RM theory. Transitions in atoms in RM are shown to dominate. (3) The inverted RM medium will optically amplify light from molecular transitions in the comet comae, in agreement with observations that many of the molecular IR emission lines lie within the emission bands from RM, or much too close to Rydberg transitions to be accidental. (4) The unexplained extended sources observed, e.g., for CO are proposed to be due to release of molecules previously incorporated in the RM clusters at low temperature. Such clusters may be the very small particles observed by space probes. (5) Finally, the largely unexplained measurements of the degree of linear polarization of scattered sunlight from comets are explained as due to scattering by the planar RM clusters. Quantitative agreement is demonstrated.     

The thermal history of the intergalactic medium

At redshifts z ≳2, most of the baryons reside in the smooth intergalactic medium which is responsible for the low column density Ly α forest. This photoheated gas follows a tight temperature–density relation which introduces a cut-off in the distribution of widths of the Ly α absorption lines ( b -parameters) as a function of column density. We have measured this cut-off in a sample of nine high-resolution, high signal-to-noise ratio quasar spectra and determined the thermal evolution of the intergalactic medium in the redshift range 2.0–4.5. At a redshift z ∼3, the temperature at the mean density shows a peak and the gas becomes nearly isothermal. We interpret this as evidence for the reionization of He  ii .     

Intergalactic Extinction and the Quasar Cut-off

The intergalactic extinction in FRIEDMANN (with A = o) universes homogeneously filled with dust grains is calculated assuming the extinction to be 0.5 mag at z = 1 and a λ⁻¹ wavelength dependence. With the resulting intergalactic extinction the number of quasars which should be observed at different redshifts are estimated assuming two different luminosity functions and a density evolution of the quasars according to M. SCHMIDT (1970, 1972). The expected number of quasars decreases rapidly with increasing redshift between z = 2 and z = 3. The observed number-magnitude relation by G. A. RICHTER (1975) is well represented.     

Probing the growth of supermassive black holes at z > 6 with LOFAR

H  ii regions surrounding supermassive black holes (SMBHs) in an otherwise still neutral intergalactic medium (IGM) are likely to be the most easily detectable sources by future 21-cm experiments like LOFAR. We have made predictions for the size distribution of such H  ii regions for several physically motivated models for BH growth at high redshift and compared this to the expected LOFAR sensitivity to these sources. The number of potentially detectable H  ii regions does not only depend on the ionization state of the IGM and the decoupling of the spin temperature of the neutral hydrogen from the cosmic microwave background temperature, but is also strongly sensitive to the rate of growth of BHs at high redshift. If the SMBHs at redshift 6 were built up via continuous Eddington-limited accretion from low mass seed BHs at high redshift, then LOFAR is not expected to detect isolated QSO H  ii regions at redshifts much larger than 6, and only if the IGM is still significantly neutral. If the high-redshift growth of BHs starts with massive seed BHs and is driven by short-lived accretion events following the merging of BH hosting galaxies then the detection of H  ii regions surrounding SMBHs may extend to redshifts as large as 8–9 but is still very sensitive to the redshift to which the IGM remains significantly neutral. The most optimistic predictions are for a model where the SMBHs at z > 6 have grown slowly. H  ii regions around SMBHs may then be detected to significantly larger redshifts.     

Apparent magnitudes of high redshift Type 1a supernovae and intergalactic graphite whiskers

The concept of a Universe undergoing an acceleration in its expansion rate and predicating the existence of dark energy is based on observed deficits in brightness of Type 1a supernovae at high redshifts, amounting to Δ m～0.3–0.5. We show that the effect of intergalactic graphite whiskers of radii in the general range 0.03–0.07 μm and lengths in excess of ～5 μm will be to mimic the effects of dark energy in the redshift magnitude relation for Type 1a supernovae. The mean intergalactic density of whiskers required for such an effect is ～3×10^?34 g cm^?3, about 10^?5 of the critical closure density.     

The properties of Lyα emitting galaxies in hierarchical galaxy formation models

We present detailed predictions for the properties of Lyα-emitting galaxies in the framework of the Λ cold dark matter cosmology, calculated using the semi-analytical galaxy formation model galform . We explore a model that assumes a top-heavy initial mass function in starbursts and that has previously been shown to explain the sub-millimetre number counts and the luminosity function of Lyman-break galaxies at high redshift. We show that this model, with the simple assumption that a fixed fraction of Lyα photons escape from each galaxy, is remarkably successful at explaining the observed luminosity function of Lyα emitters (LAEs) over the redshift range  3 < z < 6.6  . We also examine the distribution of Lyα equivalent widths and the broad-band continuum magnitudes of emitters, which are in good agreement with the available observations. We look more deeply into the nature of LAEs, presenting predictions for fundamental properties such as the stellar mass and radius of the emitting galaxy and the mass of the host dark matter halo. The model predicts that the clustering of LAEs at high redshifts should be strongly biased relative to the dark matter, in agreement with observational estimates. We also present predictions for the luminosity function of LAEs at   z > 7  , a redshift range that is starting to be be probed by near-infrared surveys and using new instruments such as the Dark Ages Z Lyman Explorer (DAzLE).     

Maintenance of spiral arms and galactic magnetic field configurations

Of the various proposed mechanisms to maintain spiral arms in spiral galaxies, three have been supported by observations, statistics, or theories (bar, companion, extended solid-body rotation curve). It is shown here that in the presence of a central bar or oval distirtion to maintain spiral arms, the global magnetic field lines also follow the spiral shape of the arms. Excluding then barred galaxies, it is confirmed that in the presence of a companion galaxy to maintain spiral arms, the global magnetic lines in a spiral galaxy will either follow thespiral shape of the arms (when tides are larger), or else will follow thering shape of the orbit of matter crossing spiral arms (when tides are small). In the presence of an extended solid-body rotation curve to maintain spiral arms within the solid-body rotation region, the global magnetic field lines also follow the spiral shape of the arms.The results above do not favour the hypothesis that a weak intergalactic magnetic field could have been amplified enough by gravitational contraction of a protogalaxy to give rise to the observed strength of galactic magnetic fields. On the contrary, leakage of galactic magnetic fields into intergalactic/cosmological space is expected.     

The redshift dependence of spectral index in powerful radio galaxies

We present and discuss in this paper the rest frame radio spectra (1–25 GHz) of a sample of fourteen radio galaxies atz >2 from the newly defined MRC/1Jy complete sample of 558 radio sources. These galaxies are among the most powerful radio sources known and range in luminosity from 1028-1028·8 watt Hz-1 at 1 GHz. We find that the median rest frame spectral index of this sample of galaxies atz >2 is significantly steeper than that of a matched luminosity sample of 3CRR galaxies which are at a much lower redshift (0.85 <z < 1.7). This indicates that spectral index correlates primarily with redshift, at least in the luminosity range considered here. The difference between the distributions of rest frame spectral curvatures for the two samples does not appear to be statistically significant. We suggest a new explanation for the steeper spectra of radio galaxies at high redshift involving steeper electron energy spectra at injection. Electron energy spectra are expected to steepen in a first-order Fermi acceleration process, at both non-relativistic and relativistic shock fronts, as the upstream fluid velocity decreases. This may well be the case at high redshifts: the hotter and denser circum-galactic medium at high redshifts could result in slower speeds for the hotspot and the jet material behind it. The smaller sizes of radio sources at higher redshifts provide support to this scenario. Since deceased.     

Photometric redshifts with surface brightness priors

We use galaxy surface brightness as prior information to improve photometric redshift (photo- z ) estimation. We apply our template-based photo- z method to imaging data from the ground-based VVDS survey and the space-based GOODS field from HST , and use spectroscopic redshifts to test our photometric redshifts for different galaxy types and redshifts. We find that the surface brightness prior eliminates a large fraction of outliers by lifting the degeneracy between the Lyman and 4000-Å breaks. Bias and scatter are improved by about a factor of 2 with the prior in each redshift bin in the range  0.4 < z < 1.3  , for both the ground and space data. Ongoing and planned surveys from the ground and space will benefit, provided that care is taken in measurements of galaxy sizes and in the application of the prior. We discuss the image quality and signal-to-noise ratio requirements that enable the surface brightness prior to be successfully applied.     

Existence and amount of intergalactic dust

The existence of intergalactic dust has been proved by the following observational facts: the decrease of the numbers of distant galaxies and clusters of galaxies behind the central regions of near clusters of galaxies; the different distributions of RR Lyrae stars and galaxies near ι Microscopii (Hoffmeister's cloud); the dependence of colour excesses of galaxies on supergalactic coordinates as well as on the surface density of bright galaxies; the colour index vs redshift correlation of quasistellar objects. The densities of intergalactic dust are estimated to be between 5×10^?30 g cm^?3 (near the centers of clusters of galaxies) and 2×10^?34 g cm^?3 (in general intergalactic space). The grains may be formed either in the early phases of the Universe (25相似文献   

The evolution of massive black hole seeds

We investigate the evolution of high-redshift seed black hole masses at late times and their observational signatures. The massive black hole seeds studied here form at extremely high redshifts from the direct collapse of pre-galactic gas discs. Populating dark matter haloes with seeds formed in this way, we follow the mass assembly of these black holes to the present time using a Monte Carlo merger tree. Using this machinery, we predict the black hole mass function at high redshifts and at the present time, the integrated mass density of black holes and the luminosity function of accreting black holes as a function of redshift. These predictions are made for a set of three seed models with varying black hole formation efficiency. Given the accuracy of present observational constraints, all three models can be adequately fitted. Discrimination between the models appears predominantly at the low-mass end of the present-day black hole mass function which is not observationally well constrained. However, all our models predict that low surface brightness, bulgeless galaxies with large discs are least likely to be sites for the formation of massive seed black holes at high redshifts. The efficiency of seed formation at high redshifts has a direct influence on the black hole occupation fraction in galaxies at   z = 0  . This effect is more pronounced for low-mass galaxies. This is the key discriminant between the models studied here and the Population III remnant seed model. We find that there exist a population of low-mass galaxies that do not host nuclear black holes. Our prediction of the shape of the M _BH–σ relation at the low-mass end is in agreement with the recent observational determination from the census of low-mass galaxies in the Virgo cluster.     

Topology and geometry of the CfA2 redshift survey

We analyse the redshift space topology and geometry of the nearby Universe by computing the Minkowski functionals of the Updated Zwicky Catalogue (UZC). The UZC contains the redshifts of almost 20 000 galaxies, is 96 per cent complete to the limiting magnitude m _Zw=15.5, and includes the Center for Astrophysics (CfA) Redshift Survey (CfA2). From the UZC we can extract volume-limited samples reaching a depth of 70  h ⁻¹ Mpc before sparse sampling dominates. We quantify the shape of the large-scale galaxy distribution by deriving measures of planarity and filamentarity from the Minkowski functionals. The nearby Universe shows a large degree of planarity and a small degree of filamentarity. This quantifies the sheet-like structure of the Great Wall, which dominates the northern region (CfA2N) of the UZC. We compare these results with redshift space mock catalogues constructed from high-resolution N -body simulations of two cold dark matter (CDM) models with either a decaying massive neutrino ( τ CDM) or a non-zero cosmological constant (ΛCDM). We use semi-analytic modelling to form and evolve galaxies in these dark matter‐only simulations. We are thus able, for the first time, to compile redshift space mock catalogues which contain galaxies, along with their observable properties, rather than dark matter particles alone. In both models the large-scale galaxy distribution is less coherent than the observed distribution, especially with regard to the large degree of planarity of the real survey. However, given the small volume of the region studied, this disagreement can still be a result of cosmic variance, as shown by the agreement between the ΛCDM model and the southern region of CfA2.     

The imprint of cosmic reionization on galaxy clustering

We consider the effect of reionization on the clustering properties of galaxy samples at intermediate redshifts ( z ∼ 0.3–5.5). Current models for the reionization of intergalactic hydrogen predict that overdense regions will be reionized early, thus delaying the build-up of stellar mass in the progenitors of massive lower redshift galaxies. As a result, the stellar populations observed in intermediate-redshift galaxies are somewhat younger and hence brighter in overdense regions of the Universe. Galaxy surveys would therefore be sensitive to galaxies with a somewhat lower dark matter mass in overdense regions. The corresponding increase in the observed number density of galaxies can be parametrized as a galaxy bias due to reionization. We model this process using merger trees combined with a stellar synthesis code. Our model demonstrates that reionization has a significant effect on the clustering properties of galaxy samples that are selected based on their star formation properties. The bias correction in Lyman-break galaxies (including those in proposed baryonic oscillation surveys at z < 1) is at the level of 10–20 per cent for a halo mass of  10¹² M_⊙  , leading to corrections factors of 1.5–2 in the halo mass inferred from measurements of clustering length. The reionization of helium could also lead to a sharp increase in the amplitude of the galaxy correlation function at z ∼ 3. We find that the reionization bias is approximately independent of scale and halo mass. However, since the traditional galaxy bias is mass dependent, the reionization bias becomes relatively more important for lower mass systems. The correction to the bias due to reionization is very small in surveys of luminous red galaxies at z < 1.     

The 6C** sample of steep-spectrum radio sources – II. Redshift distribution and the space density of high-redshift radio galaxies

We use the 6C** sample to investigate the comoving space density of powerful, steep-spectrum radio sources. This sample, consisting of 68 objects, has virtually complete K -band photometry and spectroscopic redshifts for 32 per cent of the sources. In order to find its complete redshift distribution, we develop a method of redshift estimation based on the K – z diagram of the 3CRR, 6CE, 6C* and 7CRS radio galaxies. Based on this method, we derive redshift probability density functions for all the optically identified sources in the 6C** sample. Using a combination of spectroscopic and estimated redshifts, we select the most radio luminous sources in the sample. Their redshift distribution is then compared with the predictions of the radio luminosity function of Jarvis et al. We find that, within the uncertainties associated with the estimation method, the data are consistent with a constant comoving space density of steep-spectrum radio sources beyond z ≳ 2.5, and rule out a steep decline.     

Evidence for Intrinsic Redshifts in Normal Spiral Galaxies

The Tully–Fisher Relationship (TFR) is utilized to identify anomalous redshifts in normal spiral galaxies. Three redshift anomalies are identified in this analysis: (1) several clusters of galaxies are examined, in which late type spirals have significant excess redshifts relative to early-type spirals in the same clusters; (2) galaxies of morphology similar to ScI galaxies are found to have a systematic excess redshift relative to the redshifts expected if the Hubble Constant is 72 km s⁻¹ Mpc⁻¹; (3) individual galaxies, pairs, and groups are identified which strongly deviate from the predictions of a smooth Hubble flow. These redshift deviations are significantly larger than can be explained by peculiar motions and TFR errors. It is concluded that the redshift anomalies identified in this analysis are consistent with previous claims for large non-cosmological (intrinsic) redshifts.     

The Hubble relation: Differences between galaxy types Sb and Sc

The most accurate data on galaxy types, corrected apparent magnitudes and redshifts as given in the Sandage-TammanRevised Shapley-Ames catalog are analyzed. It is shown that Sb galaxies of the same luminosity class as M31 and M81 define a narrow Hubble relation withH ₀=65 _–6 ⁺¹⁵ km s^–1 Mpc^–1.In contrast, Sc galaxies deviate strongly towars higher redshift from a linear, log redshift—apparent magnitude relation. Not all this deviation can be selection effect due to increasing volume sampled at increasing redshift (Malmquist bias). Physical associations of groups of galaxies in theRSA Catalog are used to establish the existence of various amounts of excess (non-velocity) redshifts among Sc and allied types of galaxies.Independent distances fromHi line width — luminosity criterion (Tully-Fisher) are analyzed. It is shown that this criterion gives much smaller distances than redshifts do for galaxies which deviate above the Hubble line. Unless the Tully-Fisher relation gives too small distances for more luminous galaxies, this confirms the excess redshift to be intrinsic to the Galaxy. But it is next demonstrated, that for low redshift galaxies, there is no discrepancy between redshift and Tully-Fisher distance even though there is a wide range of absolute magnitudes.If Tully-Fisher distances are accepted, the onlly alternative to having a Hubble constant which increases strongly with distance is to have a component of the higher redshift Sc's contributed by a non-recessional redshift. Streaming motions would have to be large, increase with distance and be always in the receding sence. It is shown here that the Sc's which deviate most from the Hubble relation and have the largest discrepancies with Tully-Filsher distances lie predominantly in the sky toward very nearby groups of galaxies. If they were at these closer distances the discordant galaxies, mostly ScI's, would have dwarfish physical properties but not so unprecedented as the large sizes which result from redshift distances.Finally the interaction of specific high redshift ScI's with nearby galaxies is presented as an independent proof that ScI's are generally small, low luminosity galaxies. This result furnishes insight into the long standing puzzle of how apparently distant ScI's can interact with nearby galaxies such as in Stephan's Quintet, Seyfert's Sextet and NGC 4151/4156.     

Redshift periodicities, The Galaxy-Quasar Connection

The Lehto-Tifft redshift quantization model is used to predict the redshift distribution for certain classes of quasars, and for galaxies in the neighborhood of z = 0.5. In the Lehto-Tifft model the redshift is presumed to arise from time dependent decay from an origin at the Planck scale; the decay process is a form of period doubling. Looking back in time reveals earlier stages of the process where redshifts should correspond to predictable fractions of the speed of light. Quasar redshift peaks are shown to correspond to the earliest simple fractions of c as predicted by the model. The sharp peaks present in deep field galaxy redshifts surveys are then shown to correspond to later stages in such a decay process. Highly discordant redshift associations are expected to occur and shown to be present in the deep field surveys. Peaks in redshift distributions appear to represent the spectrum of possible states at various stage of the decay process rather than physical structures. This revised version was published online in August 2006 with corrections to the Cover Date.     

Confirmation of the effectiveness of submm source redshift estimation based on rest-frame radio–FIR photometry

We present a comparison between the published optical, infrared (IR) and CO spectroscopic redshifts of 15 (sub)mm galaxies and their photometric redshifts as derived from long-wavelength (radio–mm–far-IR) photometric data. The redshift accuracy measured for 12 submillimetre (submm) galaxies with at least one robustly determined colour in the radio–mm–far-IR regime is  δ z ≈ 0.30 (rms)  . Despite the wide range of spectral energy distributions in the local galaxies that are used in an unbiased manner as templates, this analysis demonstrates that photometric redshifts can be efficiently derived for submm galaxies with a precision of  δ z < 0.5  using only the rest-frame far-IR to radio wavelength data.     

Starburst galaxies – An observer’s view

Starbursts are the most efficient producers of metals in the Universe at low redshifts. They produce enough energy to driveoutflows of material from their disks.This makes them important objects to study in order to understand the chemical evolution not only of the interstellar medium (ISM) in the starburst galaxies themselves, but also of the intergalactic medium (IGM) in their vicinity. However, several key quantities of starbursts that are neededas input to models of their ISM are still ill-constrained. Some of these critical parameters are e.g. the metalabundances of hot ionized gas, the ionization state ofwarm ionized gas, the amount of energy deposited intothe ambient by a starburst, the efficiency of itsconversion into mechanical energy and thus the totalkinetic energy of the star formation-driven outflowsand their kinematics. The latter are important when considering under whichcircumstances matter energized by a starburst will reach the so-called ‘blowout’ condition, i.e. supersede the threshold energy starting at which local energy injection into the ISM can drive an outflow first into the halo (where metal re-distribution might be very efficient) and eventually out into intergalactic space. I will discuss here a few of these quantities, how we canmeasure them better than in the past, and in which way some of our observing techniques need to be improved in order toobtain better constraints from the data.