The Origin of Cosmic Structures Part 3 — Supermassive Black Holes and Galaxy Cluster Evolution

In Part 1 of this work, we showed that our new model of cosmology can account for the origin of all cosmic structures ranging in size from stars up to superclusters. In this model, at the time of nucleosynthesis, an imprint embedded in the vacuum regulated the creation of the protons (and electrons) that later made up the structures. Immediately after nucleosynthesis and for a considerable period afterward, the evolution was completely determined by the expansion of the universe. Gradually, however, gravitational influences became more important until finally, the expansion of the structures-to-be ceased at their zero velocity points. Stars, galaxies, and galaxy clusters all reached their zero velocity points more or less simultaneously at the usually accepted time of the beginning of galaxy formation. From that point onward, the evolution gravitation came to dominate the evolution although the expansion still exerted its influence. In this paper, we examine the subsequent cluster evolution in some detail. We establish the conditions required to prevent a free-fall collapse of the clusters and then show that galaxies with quasar-like active nuclei located within the cluster were the sources of the necessary radiation. We also show that the required galactic supermassive black holes were a consequence of the initial free-fall collapse of all galaxies.

Abundance Gradient from Open Clusters and Implications for the Galactic Disk Evolution

We compile a new sample of 89 open clusters with ages, distances and metallicities available. We derive a radial iron gradient of about -0.099±0.008 dex kpc^(-1) (unweighted) for the whole sample, which is somewhat greater than the most recent determination of oxygen gradient from nebulae and young stars. By dividing the clusters into age groups, we show that the iron gradient was steeper in the past and has evolved slowly in time. Current data show a substantial scatter of the cluster metallicities indicating that the Galactic disk has undergone a very rapid, inhomogeneous enrichment. Also, based on a simple, but quite successful model of chemical evolution of the Milky Way disk, we make a detailed calculation of the iron abundance gradient and its time evolution. The predicted current iron gradient is about -0.072 dex kpc^(-1). The model also predicts a steady flattening of the iron gradient with time, which agrees with the result from our open cluster sample.

A Chandra study of the massive, distant galaxy cluster SDSS J0150–1005

We present a study of a fossil cluster,SDSS J0150–1005（z 0.364）,with high spatial resolution based on the imaging spectroscopic analysis of Chandra observations.The Chandra X-ray image shows a relaxed and symmetric morphology,which indicates that SDSS J0150–1005 is a well-developed galaxy cluster with no sign of a recent merger.According to the isothermal model,its global gas temperature is 5.73±0.80 keV,and the virial mass is 6.23±1.34×1014M⊙.Compared with the polytropic temperature model,the mass calculated based on the isothermal model is overestimated by 49%±11.The central gas entropy,S0.1 r200=143.9±18.3 keV cm2,is significantly lower than the average value of normal galaxy clusters with similar temperatures.Our results indicate that SDSS J0150–1005 formed during an early epoch.

Integrated HI emission in galaxy groups and clusters

The integrated HI emission from hierarchical structures such as groups and clusters of galax- ies can be detected by FAST at intermediate redshifts. Here we propose to use FAST to study the evolution of the global HI content of clusters and groups over cosmic time by measuring their integrated HI emissions. We use the Virgo Cluster as an example to estimate the detection limit of FAST, and have estimated the integration time to detect a Virgo type cluster at different redshifts （from z = 0.1 to z ---- 1.5）. We have also employed a semi-analytic model （SAM） to simulate the evolution of HI contents in galaxy clusters. Our simulations suggest that the HI mass of a Virgo-like cluster could be 2-3 times higher and the physical size could be more than 50% smaller when redshift increases from z = 0.3 to z = 1. Thus the integration time could be reduced significantly and gas rich clusters at intermediate redshifts can be detected by FAST in less than 2 hours of integration time. For the local Universe, we have also used SAM simulations to create mock catalogs of clusters to predict the outcomes from FAST all sky surveys. Comparing with the optically selected catalogs derived by cross matching the galaxy catalogs from the SDSS survey and the ALFALFA survey, we find that the HI mass distribution of the mock catalog with 20 s of integration time agrees well with that of observations. However, the mock catalog with 120 s of integration time predicts many more groups and clusters that contain a population of low mass HI galaxies not detected by the ALFALFA survey. A future deep HI blind sky survey with FAST would be able to test such prediction and set constraints on the numerical simulation models. The observational strategy and sample selections for future FAST observations of galaxy clusters at high redshifts are also discussed.

The Origin of Cosmic Structures Part 1—Stars to Superclusters

Our original intent was to explain the origin of large HI structures. In order to understand HI structures, however, it is first necessary to understand the origin of both galaxies and galaxy clusters. Explaining their origin is the purpose of Part 1 of this work. In our new model of cosmology, the creation of protons during nucleosynthesis was regulated by an imprint embedded in the vacuum in a manner that eventually resulted in the cosmic structures we now observe. Immediately after nucleosynthesis and for a considerable period afterward, the evolution was dominated by the expansion of the universe. Gradually, gravitational influences became important until eventually, the two became equal. At that point, the structures ceased to increase in size, and thereafter, their evolution was dominated by the gravitational interaction of the particles. The zero-velocity point for galaxies and galaxy clusters occurred at the usually accepted time of the beginning of galaxy formation. The initial population of stars also started their compaction at that same time but, in this case, partially for reasons having to do with the temperature of the proton gas. Many details of the evolution of the structure are discussed. We discuss the equilibrium of galaxy clusters and present a model that can potentially account for the present-day energy of the intracluster gas. Another outcome is that, at the time when the galaxies reached their zero-velocity point, they were several times larger than their present-day size, a fact that is critical for understanding the origin of the larger HI rings. In Part 2 of this work, we show that the HI structures can readily be understood in terms of the model developed here.

Multicolor photometric study of M31 globular clusters

We present the photometry of 30 globular clusters （GCs） and GC candidates in 15 intermediate-band filters covering the wavelength region from - 3000 to 10000A using the archival CCD images of M31 observed as part of the Beijing - Arizona - Taiwan - Connecticut （BATC） Multicolor Sky Survey. We transform these intermediate-band photometric data into the photometry in the standard U BV RI broadbands. These M31 GC candidates are selected from the Revised Bologna Catalog （RBC V.3.5）, and most of these candidates do not have any photometric data. Therefore, the presented photometric data are a supplement to the RBC V.3.5. We find that 4 out of 61 GCs and GC candidates in RBC V.3.5 do not show any signal on the BATC images at their locations. By applying a linear fit of the distribution in the color-magnitude diagram of blue GCs and GC candidates using data from the RBC V.3.5, in this study, we find the ＂blue-tilt＂ of blue M31 GCs with a high confidence at 99.95% or 3.47cr for the confirmed GCs, and 〉 99.99% or 4.87e for GCs and GC candidates.

Positions and Spectral Energy Distributions of 41 Star Clusters in M33

We present accurate positions and multi-color photometry for 41 star clusters detected by Melnick & D'odorico in the nearby spiral galaxy M33 as a part of the BATC Color Survey of the sky in 13 intermediate-band filters from 3800 to 10 000 A. The coordinates of the clusters are found from the HST Guide Star Catalog. By aperture photometry, we obtain the spectral energy distributions of the clusters. Using the relations between the BATC intermediate-band system and UBVRI broadband system, we derive their V magnitudes and B - V colors and find that most of them are blue, which is consistent with previous findings.

The NGC 7742 star cluster luminosity function： a population analysis revisited

We re-examine the properties of the star cluster population in the circumnuclear starburst ring in the face-on spiral galaxy NGC 7742, whose young cluster mass function has been reported to exhibit significant deviations from the canonical power law. We base our reassessment on the clusters＇ luminosi- ties （an observational quantity） rather than their masses （a derived quantity）, and confirm conclusively that the galaxy＇s starburst-ring clusters--and particularly the youngest subsample, log（t yr-1） ≤7.2- show evidence of a turnover in the cluster luminosity function well above the 90% completeness limit adopted to ensure the reliability of our results. This confirmation emphasizes the unique conundrum posed by this unusual cluster population.

Chandra Studies of the X-ray gas properties of fossil systems

We study ten galaxy groups and clusters suggested in the literature to be ＂fossil systems（FSs）＂based on Chandra observations. According to the M（500）- T and LX- T relations, the gas properties of FSs are not physically distinct from ordinary galaxy groups or clusters. We also first study the f（gas, 2500）- T relation and find that the FSs exhibit the same trend as ordinary systems. The gas densities of FSs within 0.1r200 are - 10^-3cm^-3, which is the same order of magnitude as galaxy clusters. The entropies within 0.1r200（S（0.1r200）） of FSs are systematically lower than those in ordinary galaxy groups, which is consistent with previous reports, but we find their S（0.1r200）- T relation is more similar to galaxy clusters. The derived mass profiles of FSs are consistent with the Navarro, Frenk and White model in（0.1- 1）（r200）, and the relation between scale radius rs and characteristic mass density δc indicates self-similarity of dark matter halos of FSs. The ranges of rs and δc for FSs are also close to those of galaxy clusters. Therefore, FSs share more common characteristics with galaxy clusters. The special birth place of the FS makes it a distinct type of galaxy system.