Astrophysical Plasma

A luminosity-temperature relation for clusters of galaxies is derived. The two models used, take into account the angular momentum acquisition by the proto-structures during their expansion and collapse. The first one is a modification of the self-similar model (SSM) while the second one is a modification of the Punctuated Equilibria Model (Cavaliere et al. 1999). In both models the mass-temperature relation (M-T) used is based on the calculations of Del Popolo (2002b). We show that the above models lead, in X-rays, to a luminosity-temperature relation that scales as L ∝ T 5 , at scale of groups, flattening to L ∝ T 3 for rich clusters and converging to L ∝ T 2 at higher temperatures. However a fundamental result of our paper is that the non-similarity in the L-T relation, can be explained by a simple model that takes into account the amount of the angular momentum of a proto-structure. This result is in disagreement with the widely accepted idea that the above non-similarity is due to non-gravitating processes as those of heating/cooling.

X-ray lines have been recently detected in the afterglows of a few gamma-ray bursts. We derive constraints on the physical conditions in the line-emitting gas, using as an example the multiple K α lines detected by in GRB 011211. We argue that models previously discussed in the literature require either a very extreme geometry or too much mass in the line-emitting region. We propose a new model in which gamma-rays and radiation from the early x-ray afterglow are back-scattered by an electron-positron pair screen at a distance of about 10 14 -10 15 cm from the source and irradiate the expanding outer layers of the supernova ejecta, thereby producing x-ray lines. The model suffers from fewer problems compared to previous models. It also has the advantage of requiring only a single explosion to produce both the GRB and the supernova ejecta, in contrast to most other models for the lines which require the supernova to go off days or weeks prior to the GRB. The model, however, has difficulty explaining the > 10 48 ergs of energy emitted in the x-ray lines, which requires somewhat extreme choices of model parameters. The difficulties associated with the various models are not particular to GRB 011211. They are likely to pose a problem for any GRB with x-ray lines.

A computational study of the reactions of hydroxylamine and its ionized and protonated derivatives with acetic acid is provided. The reaction of neutral hydroxylamine with acetic acid, despite being clearly exothermic, involves a very large energy barrier. The reaction of ionized hydroxylamine with acetic acid is also clearly exothermic, but again a significant energy barrier is found (around 24 kcal mol -1 at the CCSD(T) level). The reaction of the most stable protonated isomer of hydroxylamine, NH 3 OH + , with acetic acid also involves a high barrier (more than 27 kcal mol -1 at the CCSD(T) level). Only the higher energy isomer, NH 2 OH + 2 , leads to a sensibly lower energy barrier (about 2.3 kcal mol -1 at the CCSD(T) level). Nevertheless, an estimate of the reaction coefficient at low temperatures such as those reigning in the interstellar medium gives very low values. Therefore, it seems that precursors of interstellar glycine could not be efficiently produced from the reactions of hydroxylamine-derived ions with acetic acid.

The initial physical conditions of high-mass stars and protoclusters remain poorly characterized. To this end, we present the first targeted ALMA Band 6 1.3 mm continuum and spectral line survey toward high-mass starless clump candidates, selecting a sample of 12 of the most massive candidates ( ) within . The joint array maps have a high spatial resolution of ( , θ syn ≈ 0.″8) and have high point-source mass-completeness down to at (or column density sensitivity of ). We discover previously undetected signposts of low-luminosity star formation from and bipolar outflows and other signatures toward 11 out of 12 clumps, showing that current MIR/FIR Galactic plane surveys are incomplete to low- and intermediate-mass protostars ( ), and emphasizing the necessity of high-resolution follow-up. We compare a subset of the observed cores with a suite of radiative transfer models of starless cores. We find a high-mass starless core candidate with a model-derived mass consistent with when inte...

Introduction: Calcium, Aluminium rich inclusions are the earliest formed solids of the Solar system. Their abundance, mineralogy, typical (mean) size, chemical and isotopic signatures vary significantly amongst different groups of chondrites and to some degree within individual groups [1]. Corundum (Al2O3) followed by Hibonite (CaAl12O19) are the first predicted mineral phases to form from a cooling gas of solar composition. However, both phases are rare and predominantly found in carbonaceous chondrites of CM (Murchison) and CH/CB (High/Bencubbin) type. A much rarer class of refractory inclusions are Hibonitepyroxene spherules (hereafter referred as HIXs). HIXs are characterised by presence of hibonite laths that are surrounded by, mostly glassy, Ca, Al-rich pyroxene in a spherical shape. Notwithstanding their diminutive size (10-170μm diameter) and rarity (only nine such objects were described) they show unique exotic characteristics: (i) largest anomalies in δCa (-45 to +40 ‰) an...

Introduction: Presolar grains travelling in interstellar medium(ISM) at low density and temperature region allow molecules to be adsorbed on the grain, forming an ice mantle on the grain. The composition of ice in a molecular cloud varies with the local conditions depending on various factors like shock waves, the collision of grains, absorption of photons etc.Model calculations have been carried out to show the destructive nature of the ice mantle when exposed to the high energy galactic cosmic rays (GCR). Preliminary results indicate that ice mantle increases the effect of GCR on the Presolar core of the grain. Also, the ice mantle absorbs the energy of the ejected atoms from the core. According to observations on the lifetime estimates of large grains analyzed by Hirashita [1], SiC grains with radius ≥ 1μm seems to survive for more than 1 Gyr in the interstellar medium. For ice composition, we use the data obtained in [2] for Elias 16, a quiescent region, and compared it with a h...

The sputtering rate of presolar silicon carbide grains due to galactic cosmic rays has been computed for their experimentally deduced lifetimes (∼1 Gyr) in the interstellar medium. An ion target simulator, SDTrimSP, was used to model the sputtering of interstellar grains with varying sizes and thicknesses of the ice mantle formed around the grain during their journey through the interstellar medium. Temperature, composition, and density for four different types of molecular cloud environments (quiescent, low-mass young stellar objects (YSOs), intermediate-mass YSOs, and high-mass YSO weak processing) considered indicate the sputtering rate on the mantle ice composition depends on water composition to a certain extent. The model simulations indicate galactic cosmic ray(s) with an energy range from 10 MeV to 1 GeV are just capable of sputtering/destructing ∼13%–15% of the grain itself. This value, stretched over 1 Gyr is not as significant as the other destruction processes and theref...

We performed an in-depth exploration of the Al-Mg system for presolar graphite, SiC, and Si 3 N 4 grains found to contain large excesses of 26 Mg, indicative of the initial presence of live 26 Al. Ninety of the more than 450 presolar grains processed in this study contain well-correlated Mg Mg 26 24 d and 27 Al/ 24 Mg ratios, derived from Nano-scale Secondary Ion Mass Spectrometer depth profiles, whose isochron-like regression lines yield inferred initial Al Al 26 27 ratios that, on average, are ∼1.5-2 times larger than the ratios previously reported for the grains. The majority of presolar graphite and SiC grains are heavily affected by Al contamination, resulting in large negative Mg Mg 26 24 d intercepts of the isochron lines. Al contamination is potentially due to etching of the grains' surfaces and subsequent capture of dissolved Al during the acid dissolution of their meteorite host rocks. From the isochron fits, the magnitude of Al contamination was quantified for each grain. The amount of Al contamination on each grain was found to be random and independent of grain size, following a uniform distribution with an upper bound at 59% contamination. The Al contamination causes conventional whole-grain estimates to underpredict the initial Al Al 26 27 ratios. The presolar grains with the highest Al Al 26 27 ratios are from Type II supernovae whose isochronderived initial Al Al 26 27 ratios greatly exceed those predicted in the He/C and He/N zones of SN models.

Trace elements in various individual presolar grains serve as a tool to understand the chemical and physical conditions during the formation of presolar grains (in expanding envelope/ejecta of stars). Two scenarios that have been discussed to incorporate trace elements within the forming presolar SiC grains are: (a) condensation of trace elements as solid solutions [1, 2]. The abundances will be a function of C/O ratio, pressure, volatility and crystal structure; and (b) ion implantation of trace elements into the SiC grains. In this case abundances depend on the ionization potential of the respective element [3]. Noble gas data for presolar SiC grains indicate that ion implantation plays an important role. Quantifying the fraction of implanted trace elements might give a better idea on the physical conditions under which SiC condensation takes place. Experimental: We have measured 32 individual mainstream SiC grains, 7 SiC-agglomerates and 17 single X-grains from the Murchison and Murray meteorites using the NanoSIMS at Max-Planck-Institute for Chemistry at Mainz for Ba isotopes (except 130 Ba, 132 Ba) along with the most abundant isotopes of selected trace elements (Sr, Zr, Cs, La and Ce) [4]. Results: The trace element characteristics (normalized to Si and CI) can be summarized as follows: (1) There is a spread of two orders of magnitude for the concentrations of all trace elements, except for Cs which varies by 7 orders of magnitude. The data obtained for bulk samples of Murchison KJA-KJG grains [1] for Ce, La, Sr, Zr are compatible with those of the mainstream grains analyzed in this work. (2) There is no systematic difference between the trace element concentrations of the 17 X grain and single mainstream grains and the agglomerates. (3) Normalized Sr abundances are on average lower than Ba by an order of magnitude. (4) Except for Cs and Zr, correlations exist between Ba and the other trace elements, that is, [Ba]-[La], [Ba]-[Ce] and [Ba]-[Sr]. (5) Zr, La, Ba and Ce are enriched relative to Si and CI, whereas most of the SiC grains are depleted in Sr. (6) There is a rough negative correlation between concentrations of Ce, Ba, La, and Sr and grain size. This trend even extends to the larger KJH grains (3.4-5.9 microns) studied by [1]. The existence of a negative correlation between grain size and trace element concentration implies that at least some fraction of the Ba and other trace elements were implanted into the mainstream SiC grains. It has been proposed that 60 % of the Ba in SiC was trapped by ion implantation [3] and that the rest co-condensed into the SiC grains. The ion implantation scenario is also favored by trace element data from ICPMS measurements on bulk SiC [5]. Clearly, more theoretical work needs to be done in order to get a better understanding on how the trace elements were incorporated in presolar SiC grains.

We report the first Fe isotopic anomalies and the first Ni isotopic ratio measurements in presolar SiC grains of separate KJG from the Murchison meteorite. With NanoSIMS, we analyzed Fe and Ni in 37 X grains from Type II supernovae and 53 SiC grains of other types. The Ni/Fe and Co/Fe ratios in grains of all types are much higher than in the gas from which the grains are believed to have condensed. A majority of the X grains and a couple of mainstream grains contain Fe-rich subgrains. Most X grains have large excesses in 57 Fe, 61 Ni, and 62 Ni. 60 Ni excesses are small and the 54 Fe/ 56 Fe ratios of almost all X grains are normal. These isotopic compositions are best explained by mixing of material from the He/N zone of Type II supernovae with material from the He/C zone. The lack of any 54 Fe excesses is puzzling in view of the fact that the Si/S zone, whose contribution resulted in the 28 Si excesses in X grains, is very rich in 54 Fe. It has yet to be seen whether elemental fractionation between Si and Fe is an explanation. The 57 Fe deficits observed in a few X grains remain unexplained. In comparison to the X grains, fewer mainstream and AB grains have anomalies. Observed 62 Ni excesses in some mainstream grains are larger than predicted for AGB stars of solar metallicity and are not accompanied by corresponding 61 Ni excesses. A Y grain and a Z grain have excesses in 54 Fe and 62 Ni, but close to normal 57 Fe/ 56 Fe and 60,61 Ni/ 58 Ni ratios. These isotopic compositions are not expected for grains from low-metallicity AGB stars.

We present C, N, O, Si, Al-Mg, K, Ca, and Ti isotopic analyses of seven high-density (ORG1f, $ 2:02 2:04 g cm À3 ) graphite grains from Orgueil with 12 C/ 13 C ratios smaller than 20. The presence of 44 Ti in three of these grains indicates an origin in Type II supernovae (SNe). The 13 C excesses in these SNe grains, however, remain enigmatic. The remaining grains have extremely large Ca and Ti isotopic anomalies, some of which are much larger than those predicted for envelopes of asymptotic giant branch (AGB) stars. These anomalies in conjunction with low 12 C/ 13 C ratios can only be explained by pure nucleosynthetic He-shell components of AGB stars. Born-again AGB stars that experience a late He flash are able to explain the low 12 C/ 13 C ratios of some of the grains along with the presence of extreme enrichments in the Ca and Ti isotopes. This study indicates that high-density graphite grains have multiple stellar sources: SNe and born-again AGB stars, in addition to the previously established low-metallicity AGB stars.

Noble gas isotopes in presolar silicon carbide (SiC) dust grains from primitive meteorites provide, together with major element isotopic compositions, insight into the nucleosynthetic output of different types of evolved stars >4.5 Gyr ago. We report here new results from helium and neon isotopic analyses of single presolar SiC grains with sizes between 0.6 and 6.3 m using an ultrahigh sensitivity mass spectrometer. These noble gas studies were complemented by an ion microprobe study (NanoSIMS) of Si, C, and N isotopic compositions of the same grains. About 40%, or 46 of the 110 grains analyzed, contain nucleosynthetic 22 Ne and/or 4 He from their parent stars above our mass spectrometer's detection limit. We discuss the possible stellar sources using isotopic ratios as constraints combined with new model predictions for low-to intermediate-mass (1.5, 2, 3, and 5 M ) asymptotic giant branch (AGB) stars of different metallicities (1, 1/2, 1/3, and 1/6 Z ). Most SiC grains are of the mainstream type and originated in low-mass AGB stars. We find a higher-than-expected percentage of A/B type grains, with some containing 22 Ne and/or 4 He. In addition, we find one noble gasYrich nova grain candidate, one supernova grain ( X-type grain), and one 22 Ne-rich X-or Z-type grain candidate.

We have studied more than 2000 presolar silicon carbide (SiC) grains from the Murchison CM2 chondrite in the size range 0.2-0.5 μm for C-and Si-isotopic compositions. In a subset of these grains, we also measured N-, Mg-Al-, S-, and Ca-Ti-isotopic compositions as well as trace element concentrations. The overall picture emerging from the isotope data is quite comparable with that of larger grains, except for the abundances of grains from Type II supernovae (SNeII) and low-metallicity asymptotic giant branch (AGB) stars. Especially, the latter are much more abundant among submicrometer-sized grains than among micrometer-sized grains. This implies that SiC grains from lower-than-solar-metallicity AGB stars are on average smaller than those from solar metallicity AGB stars which provided the majority of presolar SiC grains. We identified five grains with large enrichments in 29 Si (up to 3.5× solar) and 30 Si (up to 3.9× solar in three of these grains). These grains are most likely from SNeII. The isotopically light S ( 32 S/ 34 S of 2× solar) together with the heavy Si in one of these grains suggests that molecule formation precedes macroscopic mixing and dust formation in SNII ejecta. This adds to the complexity of SN mixing calculations and should be considered in future studies. In total, about 2% of the presolar SiC grains in the size range 0.2-0.5 μm appear to come from SNeII. This is about a factor of 2 higher than for micrometer-sized grains and suggests that SNeII, on average, produce smaller SiC grains than solar metallicity AGB stars. The high 29 Si/ 30 Si ratio in one of the SN grains suggests that current SN models underestimate the 29 Si production in the C-and Ne-burning regions by about a factor of 2. It is shown that with this adjustment the solar 29 Si/ 28 Si ratio can be well reproduced in Galactic chemical evolution models and that a merger of our Galaxy with a low-metallicity satellite some 1.5 Gyr before solar system formation could account for the slope 1.3 of the Si mainstream line.

A rare but important constituent of presolar dust in primitive meteorites is corundum (Al 2 O 3 ). Most of these grains are believed to originate from red giant branch (RGB) and asymptotic giant branch (AGB) stars as evidenced from O-isotopic signatures and abundances of now extinct 26 Al [1]. Models of RGB/AGB stars with initially solar O predict lower than solar 18 O/ 16 O and higher than solar 17 O/ 16 O in the envelope [2, 3], a result of the dredge-up of matter that experienced H burning. A detailed comparison between the grain data and model predictions suggests that parent stars with different initial compositions (metallicities) must be considered [1,, i.e., the grains carry not only the signature of stellar nucleosynthesis but also that of the Galactic chemical evolution (GCE). Other elements that clearly show imprints of stellar nucleosynthesis and GCE in their isotopic patterns are Si and Ti in presolar SiC .

We report isotopic analyses (C, N, O, Si, Al-Mg, K, Ca, and Ti) for 44 new high-density graphite grains from Orgueil. Several grains have large Ca and Ti anomalies that indicate a supernova origin. Some grains with extreme Ca and Ti anomalies were also fo

Presolar SiC grains from supernovae (type X) have excesses in 57Fe on the order of~ 1000‰[1]. Two interesting points to be noted along with these excesses are:(a) 56Fe/54Fe ratios are normal (within 3σ) for all 36 SiC X grains analyzed and (b) 19 grains with ...

A questao que nos mobiliza nesse trabalho, reside em compreender como alunos do 5° ano aprendem Ciencias a partir de situacoes-problema (SP). Para isso, apostamos na realizacao de uma pesquisa participante. Os dados coletados foram gravados durante o desenvolvimento de duas SP selecionadas e desenvolvidas com criancas. Uma atividade abordava a questao dos nutrientes e outra aspectos de localizacao geografica. As SP permitiram visualizar que os alunos se mobilizam ao se depararem com um questionamento a ser desvendado e comecam a se questionar sobre o porque das coisas acontecerem de tal maneira. Desse modo, a utilizacao de SP sinalizam um caminho que pode vir a ser potencializado no Ensino de Ciencias.

We report a transient intensity reduction/absorption burst observed at decameter wavelengths in close temporal association with an X2.0/3B flare near the disk center and the onset of a "halo" coronal mass ejection. The observed bandwidth of the burst was about 10 MHz. The size of the absorption region was estimated to be ≈28,000 km.

Highly volcanic exoplanets, which can be variously characterized as 'lava worlds', 'magma ocean worlds', or 'super-Ios' are high priority targets for investigation. The term 'lava world' may refer to any planet with extensive surface lava lakes, while the term 'magma ocean world' refers to planets with global or hemispherical magma oceans at their surface. 'Highly volcanic planets', including super-Ios, may simply have large, or large numbers of, active explosive or extrusive volcanoes of any form. They are plausibly highly diverse, with magmatic processes across a wide range of compositions, temperatures, activity rates, volcanic eruption styles, and background gravitational force magnitudes. Worlds in all these classes are likely to be the most characterizable rocky exoplanets in the near future due to observational advantages that stem from their preferential occurrence in short orbital periods and their bright day-side flux in the ...

We exploit deep integral-field spectroscopic observations with KMOS/Very Large Telescope of 240 star-forming disks at < < z 0.6 2.6 to dynamically constrain their mass budget. Our sample consists of massive ( M 10 9.8 ☉ ) galaxies with sizes  R 2 kpc e . By contrasting the observed velocity and dispersion profiles with dynamical models, we find that on average the stellar content contributes - + 32 % 7 8 of the total dynamical mass, with a significant spread among galaxies (68th percentile range f 18% 62% star -). Including molecular gas as inferred from CO-and dust-based scaling relations, the estimated baryonic mass adds up to - + 56 % 12 17 of the total for the typical galaxy in our sample, reaching ~90% at > z 2. We conclude that baryons make up most of the mass within the disk regions of high-redshift star-forming disk galaxies, with typical disks at > z 2 being strongly baryondominated within R e . Substantial object-to-object variations in both stellar and baryonic mass fractions are observed among the galaxies in our sample, larger than what can be accounted for by the formal uncertainties in their respective measurements. In both cases, the mass fractions correlate most strongly with measures of surface density. High-S star galaxies feature stellar mass fractions closer to unity, and systems with high inferred gas or baryonic surface densities leave less room for additional mass components other than stars and molecular gas. Our findings can be interpreted as more extended disks probing further (and more compact disks probing less far) into the dark matter halos that host them.

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We use a series of idealized, numerical smoothed particle hydrodynamics simulations to study the formation and evolution of galactic, gas-rich disks forming from gas infall within dark matter halos. The temperature and density structure of the gas is varied in order to differentiate between (1) simultaneous gas infall at a large range of radii and (2) the inside-out buildup of a disk. In all cases, the disks go through phases of ring formation, gravitational instability and break-up into massive clumps. Ring formation can be enhanced by a focal point effect. The position of the ring is determined by the angular momentum distribution of the material it forms from. We study the ring and clump morphologies, the characteristic properties of the resulting velocity dispersion field and the effect of star formation. In the early phases, gas accretion leads to a high vertical velocity dispersion. We find that the disk fragmentation by gravitational instability and the subsequent clump-clump interactions drive high velocity dispersions mainly in the plane of the disk while at the same time the vertical velocity dispersion dissipates. The result is a strong variation of the line-of-sight velocity dispersion with inclination angle. For a face-on view, clumps appear as minima in the (vertical) dispersion, whereas for a more edge-on view, they tend to correspond to maxima. There exists observational evidence of a systematic variation of the velocity dispersion with inclination angle in high-redshift disks, which could be partly explained by our simulation results. Additional energetic sources to drive velocity dispersion that are not included in our models are also expected to contribute to the observational results.

We present binary galaxy merger simulations with varying mass ratios and different progenitor morphologies. The simulations include mergers of gas-rich disks (Sp-Sp), of early-type galaxies and disks (E-Sp, mixed mergers), and mergers of early-type galaxies (E-E, dry mergers). We follow the dynamics of gas, stars and dark matter, and include radiative cooling, star formation and black hole (BH) accretion and the associated feedback processes as in Springel et al. We study the mass assembly of the BHs and discuss technical issues of the implemented model in detail. For Sp-Sp mergers, the peak star formation rate and BH accretion rate decrease and the growth timescales of the central black holes and newly formed stars increase with higher progenitor mass ratios. The peak BH accretion rate typically occurs shortly after the time of BH merging for low progenitor mass ratios (e.g. 3:1 and lower), whereas for higher progenitor mass ratios there is no clear correlation between the peak BH accretion rate and BH merging time. The termination of star formation by BH feedback in disk mergers is significantly less important for higher progenitor mass ratios (e.g. 3:1 and higher). In addition, the inclusion of BH feedback suppresses efficiently star formation in dry E-E mergers and mixed E-Sp mergers. All merger remnants, independent of their progenitors, follow the observed relations between the central BH mass and the stellar velocity dispersion (M BH -σ), the bulge mass (M BH -M * ) and the bulge binding energy (M BH -M * σ 2 ), with the dominant source of scatter arising from variations in the initial gas mass fraction. The normalizations for all relations and the simulated slope of the M BH -σ and M BH -M * σ 2 relations are in good agreement with the observations, whereas the simulated slope of the M BH -M * relation is slightly steeper compared to the observations. This indicates that the simple BH feedback model self-regulates the mass growth of the BHs in accordance with the observed relations for a very wide range of merger progenitors.

We study the evolution of black holes (BHs) on the M BH -σ and M BH -M bulge planes as a function of time in disk galaxies undergoing mergers. We begin the simulations with the progenitor black hole masses being initially below (∆ log M BH,i ∼ -2), on (∆ log M BH,i ∼ 0) and above (∆ log M BH,i ∼ 0.5) the observed local relations. The final relations are rapidly established after the final coalescence of the galaxies and their BHs. Progenitors with low initial gas fractions (f gas = 0.2) starting below the relations evolve onto the relations (∆ log M BH,f ∼ -0.18), progenitors on the relations stay there (∆ log M BH,f ∼ 0) and finally progenitors above the relations evolve towards the relations, but still remaining above them (∆ log M BH,f ∼ 0.35). Mergers in which the progenitors have high initial gas fractions (f gas = 0.8) evolve above the relations in all cases (∆ log M BH,f ∼ 0.5). We find that the initial gas fraction is the prime source of scatter in the observed relations, dominating over the scatter arising from the evolutionary stage of the merger remnants. The fact that BHs starting above the relations do not evolve onto the relations, indicates that our simulations rule out the scenario in which overmassive BHs evolve onto the relations through gas-rich mergers. By implication our simulations thus disfavor the picture in which supermassive BHs develop significantly before their parent bulges.

Many observed massive star-forming z ≈ 2 galaxies are large disks that exhibit irregular morphologies, with ≈1 kpc, ≈10 8 -10 10 M clumps. We present the largest sample to date of high-resolution cosmological smoothed particle hydrodynamics simulations that zoom-in on the formation of individual M * ≈ 10 10.5 M galaxies in ≈10 12 M halos at z ≈ 2. Our code includes strong stellar feedback parameterized as momentum-driven galactic winds. This model reproduces many characteristic features of this observed class of galaxies, such as their clumpy morphologies, smooth and monotonic velocity gradients, high gas fractions (f g ≈ 50%), and high specific star formation rates ( 1 Gyr -1 ). In accord with recent models, giant clumps (M clump ≈ (5 × 10 8 -10 9 ) M ) form in situ via gravitational instabilities. However, the galactic winds are critical for their subsequent evolution. The giant clumps we obtain are short-lived and are disrupted by wind-driven mass loss. They do not virialize or migrate to the galaxy centers as suggested in recent work neglecting strong winds. By phenomenologically implementing the winds that are observed from high-redshift galaxies and in particular from individual clumps, our simulations reproduce well new observational constraints on clump kinematics and clump ages. In particular, the observation that older clumps appear closer to their galaxy centers is reproduced in our simulations, as a result of inside-out formation of the disks rather than inward clump migration.

We present Hα integral field spectroscopy of well resolved, UV/optically selected z~2 star-forming galaxies as part of the SINS survey with SINFONI on the ESO VLT. Our laser guide star adaptive optics and good seeing data show the presence of turbulent rotating star forming rings/disks, plus central bulge/inner disk components, whose mass fractions relative to total dynamical mass appears to scale with [NII]/Hα flux ratio and 'star formation' age. We propose that the buildup of the central disks and bulges of massive galaxies at z~2 can be driven by the early secular evolution of gas-rich 'proto'-disks. High redshift disks exhibit large random motions. This turbulence may in part be stirred up by the release of gravitational energy in the rapid 'cold' accretion flows along the filaments of the cosmic web. As a result dynamical friction and viscous processes proceed on a time scale of <1 Gyr, at least an order of magnitude faster than in z~0 disk galaxies. Early secular evolution thus drives gas and stars into the central regions and can build up exponential disks and massive bulges, even without major mergers. Secular evolution along with increased efficiency of star formation at high surface densities may also help to account for the short time scales of the stellar buildup observed in massive galaxies at z~2.

We present results from our Very Large Telescope large program to study the dynamical evolution of local Ultraluminous Infrared Galaxies (ULIRGs) and QSOs. Expanding previous studies by , our data now consist of high resolution, long-slit H-and K-band spectra of 54 ULIRGs. This paper mainly presents the kinematics of sources that have coalesced into a single nucleus. The stellar kinematics, extracted from the CO rovibrational bandheads in our spectra, indicate that ULIRG remnants are dynamically heated systems with a mean dispersion of 157 km s -1 . The combination of kinematic, structural, and photometric properties of the remnants indicate that they mostly originate from major encounters (in agreement with Dasyra et al. 2006) and that they result in the formation of dispersion-supported systems (elliptical galaxies of the order ∼10 10 -10 11 M ). Placing ULIRGs on the fundamental plane of early-type galaxies indicates that the end products of ultraluminous mergers are typically less massive and extended than giant ellipticals (in good agreement with . Converting the host dispersion into black hole mass with the aid of the M BHσ relation yields black hole mass estimates of the order 10 7 -10 8 M and high accretion rates (of Eddington efficiencies often > 0.5).

Compact groups (CGs) of galaxies -relatively poor groups of galaxies in which the typical separations between members is of the order of a galaxy diameter -offer an exceptional laboratory for the study of dense galaxian environments with short (< 1 Gyr) dynamical time-scales.

We compute the angular power spectrum C ℓ from 1.5 million galaxies in early SDSS data on large angular scales, ℓ ∼ < 600. The data set covers about 160 square degrees, with a characteristic depth of order 1h -1 Gpc in the faintest (21 < r * < 22) of our four magnitude bins. Cosmological interpretations of these results are presented in a companion paper by Dodelson et al. (2001). The data in all four magnitude bins are consistent with a simple flat "concordance" model with nonlinear evolution and linear bias factors of order unity. Nonlinear evolution is particularly evident for the brightest galaxies. A series of tests suggest that systematic errors related to seeing, reddening, etc., are negligible, which bodes well for the sixtyfold larger sample that the SDSS is currently collecting. Uncorrelated error bars and well-behaved window functions make our measurements a convenient starting point for cosmological model fitting.

Compact groups (CGs) of galaxies--relatively poor groups of galaxies in which the typical separations between members is of the order of a galaxy diameter--offer an exceptional laboratory for the study of dense galaxian environments with short (&lt;1Gyr) dynamical time-scales. In this paper, we present an objectively defined catalog of CGs in 153 sq deg of the Sloan Digital Sky Survey

We measure the large-scale real-space power spectrum PðkÞ by using a sample of 205,443 galaxies from the Sloan Digital Sky Survey, covering 2417 effective square degrees with mean redshift z % 0:1. We employ a matrix-based method using pseudo-Karhunen-Loe `ve eigenmodes, producing uncorrelated minimum-variance measurements in 22 k-bands of both the clustering power and its anisotropy due to redshift-space distortions, with narrow and well-behaved window functions in the range 0:02 h Mpc À1 < k < 0:3 h Mpc À1 . We pay particular attention to modeling, quantifying, and correcting for potential systematic errors, nonlinear redshift distortions, and the artificial red-tilt caused by luminosity-dependent bias. Our results are robust to omitting angular and radial density fluctuations and are consistent between different parts of the sky. Our final result is a measurement of the real-space matter power spectrum PðkÞ up to an unknown overall multiplicative bias factor. Our calculations suggest that this bias factor is independent of scale to better than a few percent for k < 0:1 h Mpc À1 , thereby making our results useful for precision measurements of cosmological parameters in conjunction with data from other experiments such as the Wilkinson Microwave Anisotropy Probe satellite. The power spectrum is not well-characterized by a single power law but unambiguously shows curvature. As a simple characterization of the data, our measurements are well fitted by a flat scale-invariant adiabatic cosmological model with h m ¼ 0:213 AE 0:023 and 8 ¼ 0:89 AE 0:02 for L Ã galaxies, when fixing the baryon fraction b = m ¼ 0:17 and the Hubble parameter h ¼ 0:72; cosmological interpretation is given in a companion paper.

We report the discovery of two well-defined tidal tails emerging from the sparse remote globular cluster Palomar 5. These tails stretch out symmetrically to both sides of the cluster in the direction of constant Galactic latitude and subtend an angle of 2.6 • on the sky. The tails have been detected in commissioning data of the Sloan Digital Sky Survey (SDSS), providing deep five-color photometry in a 2.5 • wide band along the equator. The stars in the tails make up a substantial part (∼ 1/3) of the current total population of cluster stars in the magnitude interval 19.5 ≤ i * ≤ 22.0. This reveals that the cluster is subject to heavy mass loss. The orientation of the tails provides an important key for the determination of the cluster's Galactic orbit.

We present the large-scale correlation function measured from a spectroscopic sample of 46,748 luminous red galaxies from the Sloan Digital Sky Survey. The survey region covers 0.72h -3 Gpc 3 over 3816 square degrees and 0.16 < z < 0.47, making it the best sample yet for the study of large-scale structure. We find a well-detected peak in the correlation function at 100h -1 Mpc separation that is an excellent match to the predicted shape and location of the imprint of the recombination-epoch acoustic oscillations on the low-redshift clustering of matter. This detection demonstrates the linear growth of structure by gravitational instability between z ≈ 1000 and the present and confirms a firm prediction of the standard cosmological theory. The acoustic peak provides a standard ruler by which we can measure the ratio of the distances to z = 0.35 and z = 1089 to 4% fractional accuracy and the absolute distance to z = 0.35 to 5% accuracy. From the overall shape of the correlation function, we measure the matter density Ω m h 2 to 8% and find agreement with the value from cosmic microwave background (CMB) anisotropies. Independent of the constraints provided by the CMB acoustic scale, we find Ω m = 0.273 ± 0.025 + 0.123(1 + w 0 ) + 0.137Ω K . Including the CMB acoustic scale, we find that the spatial curvature is Ω K = -0.010 ± 0.009 if the dark energy is a cosmological constant. More generally, our results provide a measurement of cosmological distance, and hence an argument for dark energy, based on a geometric method with the same simple physics as the microwave background anisotropies. The standard cosmological model convincingly passes these new and robust tests of its fundamental properties. Subject headings: cosmology: observations -large-scale structure of the universe -distance scalecosmological parameters -cosmic microwave background -galaxies: elliptical and lenticular, cD

We present initial results for counts in cells statistics of the angular distribution of galaxies in early data from the Sloan Digital Sky Survey (SDSS). We analyze a rectangular stripe 2.5 • wide, covering approximately 160 sq. degrees, containing over 10 6 galaxies in the apparent magnitude range 18 < r ′ < 22, with

The angular distribution of galaxies encodes a wealth of information about large scale structure. Ultimately, the Sloan Digital Sky Survey (SDSS) will record the angular positions of order 10 8 galaxies in five bands, adding significantly to 1 Based on observations obtained with the Sloan Digital Sky Survey

We present measurements of parameters of the 3-dimensional power spectrum of galaxy clustering from 222 square degrees of early imaging data in the Sloan Digital Sky Survey. The projected galaxy distribution on the sky is expanded over a set of Karhunen-Loève eigenfunctions, which optimize the signal-to-noise ratio in our analysis. A maximum likelihood analysis is used to estimate parameters that set the shape and amplitude of the 3-dimensional power spectrum. Our best estimates are Γ = 0.188±0.04 and σ 8L = 0.915 ± 0.06 (statistical errors only), for a flat universe with a cosmological constant. We demonstrate that our measurements contain signal from scales at or beyond the peak of the 3D power spectrum. We discuss how the results scale with systematic uncertainties, like the radial selection function. We find that the central 1 Based on observations obtained with the Sloan Digital Sky Survey

This paper describes the Fourth Data Release of the Sloan Digital Sky Survey (SDSS), including all survey-quality data taken through 2004 June. The data release includes five-band photometric data for 180 million objects selected over 6670 deg 2 and 673,280 spectra of galaxies, quasars, and stars selected from 4783 deg 2 of those imaging data using the standard SDSS target selection algorithms. These numbers represent a roughly 27% increment over those of the Third Data Release; all the data from previous data releases are included in the present release. The Fourth Data Release also includes an additional 131,840 spectra of objects selected using a variety of alternative algorithms, to address scientific issues ranging from the kinematics of stars in the Milky Way thick disk to populations of faint galaxies and quasars.

Voyager 1's passage beyond the heliopause provides unprecedented data on the persistence of plasma structures at the boundary between solar and interstellar space. Observations of (i) magnetic field alignment across the heliopause, (ii) AU-scale plasma density fluctuations, (iii) compression "humps" linked to solar pressure pulses, and (iv) mode conversion of compressible to incompressible waves all suggest that the heliosphere retains and transmits a continuity of information across its outer boundary. We frame these findings in terms of the Ω Law, which unifies energy-matter equivalence (E = mc²) with memory-life equivalence (M = L), formalized through the Recursive Memory Sciences (RMS) framework. In this interpretation, energy inputs (E) from solar pulses, memory carriers (M) in plasma density and magnetic topology, and continuity (C) of boundary identity interact dynamically. Reconnection events act as forgetting (F), while mode conversion represents adaptive agency (A). The falsification clause is explicit: if a heliospheric boundary can persist with continuity (C) but no memory substrate (M), Ω Law is disproved. Voyager's findings to date support the opposite: plasma structures preserve memory, and persistence follows.

Pupil-mapping is a technique whereby a uniformly-illuminated input pupil, such as from starlight, can be mapped into a non-uniformly illuminated exit pupil, such that the image formed from this pupil will have suppressed sidelobes, many orders of magnitude weaker than classical Airy ring intensities. Pupil mapping is therefore a candidate technique for coronagraphic imaging of extrasolar planets around nearby stars. Unlike most other high-contrast imaging techniques, pupil mapping is lossless and preserves the full angular resolution of the collecting telescope. So, it could possibly give the highest signal-to-noise ratio of any proposed single-telescope system for detecting extrasolar planets. Prior analyses based on pupil-to-pupil ray-tracing indicate that a planet fainter than 10 -10 times its parent star, and as close as about 2λ/D, should be detectable. In this paper, we describe the results of careful diffraction analysis of pupil mapping systems. These results reveal a serious unresolved issue. Namely, high-contrast pupil mappings distribute light from very near the edge of the first pupil to a broad area of the second pupil and this dramatically amplifies diffraction-based edge effects resulting in a limiting attainable contrast of about 10 -5 . We hope that by identifying this problem others will provide a solution.

One proposed method for finding terrestrial planets around nearby stars is to use two spacecraft-a telescope and a specially shaped occulter that is specifically designed to prevent all but a tiny fraction of the starlight from diffracting into the telescope. As the cost and observing cadence for such a mission will be driven largely by the separation between the two spacecraft, it is critically important to design an occulter that can meet the observing goals while flying as close to the telescope as possible. In this paper, we explore this tradeoff between separation and occulter diameter. More specifically, we present a method for designing the shape of the outer edge of an occulter that is as small as possible and gives a shadow that is deep enough and large enough for a 4m telescope to survey the habitable zones of many stars for Earth-like planets. In particular, we show that in order for a 4m telescope to detect in broadband visible light a planet 0.06 arcseconds from a star shining 10 10 times brighter than the planet requires a specially-shaped occulter 50m in diameter positioned about 72, 000 km in front of the telescope.

Il modello originale f(R) = R + αR² presentato nella Teoria dei Supergravitoni offre una spiegazione elegante per l'espansione accelerata dell'universo recente, ma come riconosciuto negli stessi "Sviluppi Futuri" del documento, richiede estensioni significative per spiegare le osservazioni rivoluzionarie del JWST. In particolare, le strutture cosmiche precoci e le anomalie gravitazionali richiedono una revisione fondamentale del modello che integri elementi di cosmologia non standard. Propongo qui un'estensione che unisce l'intuizione dei "supergravitoni" con le osservazioni JWST, creando un framework coerente per spiegare queste anomalie.