bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Stellar Mass Distribution of Powerful Radio Galaxies Across 1 < z < 5.2
Authors: Seymour Nick , Stern D. , De Breuck C. ,   for the SHiZRaG collaboration
Published: April 2007

AbstractWe present the results of a comprehensive Spitzer survey of 70 radio galaxies across 1 < z < 5.2. Using IRAC (3.6–8.0μm), IRS (16 μm) and MIPS (24–160 μm) imaging, we decompose the rest-frame optical to infrared spectral energy distributions into stellar, AGN, and dust components and determine the contribution of host galaxy stellar emission at rest-frame 1.6 μm (H-band). We find that the fraction of emitted light at rest-frame 1.6 μm from stars is >80% for over half the high redshift radio galaxies. The other radio galaxies have 1.6 μm stellar fractions spanning the range 20–80%. The resultant stellar luminosities imply stellar masses of 1011−12M⊙, independent of redshift, indicating that radio galaxies are amoungst the most massive galaxies observed over this redshift range. Powerful radio galaxies tend to lie in a similar region of mid-IR color-color space as unobscured AGN, despite the inferred stellar contribution to their shorter-wavelength, mid-IR SEDs. The stellar fraction of the rest-frame 1.6 μm luminosity has no correlation with redshift, radio luminosity, or rest-frame mid-IR (5 μm) luminosity. The bolometric energy output of these sources is dominated by the infrared, and the mid-IR luminosities are found to be similar to that of lower redshift (z < 1) radio galaxies. As expected, these exceptionally high mid-IR luminosities are consistent with an obscured, highly-accreting AGN. A weak, but significant, correlation of stellar mass with radio luminosity is found, consistent with earlier results.
Obtaining the (dust-obscured) star formation history using the VLA-COSMOS survey
Authors: Smolčić V. , Schinnerer E. , Scodeggio M. , Carilli C.L. , Franzetti P. , Jahnke K. 
Published: April 2007

AbstractUsing the multi-wavelength COSMOS survey (Scoville et al. 2006), we develop a method based on purely photometric data to separate the faint VLA-COSMOS radio population into star-forming (SF) galaxies and active-galactic nuclei (AGN). Based on this classification method we select SF galaxies within our sample and present first results on the cosmic (dust-obscured) star-formation history based on VLA-COSMOS (Schinnerer et al. 2006) radio data.
Sub-millimetre properties of massive star-forming galaxies at z ~ 2 in SHADES/SXDF
Authors: Takagi T. , Mortier A. M. J. , Shimasaku K. , Coppin K. , Pope A. , Ivison R. J. , Hanami H. , Serjeant S. , Dunlop J. S. 
Published: April 2007

AbstractWe study the submillimetre (submm) properties of the following near-infrared (NIR)-selected massive galaxies at high redshifts: BzK-selected star-forming galaxies (BzKs), distant red galaxies (DRGs) and extremely red objects (EROs). We used the SCUBA HAlf Degree Extragalactic Survey (SHADES), the largest uniform submm survey to date. Since BzKs are expected to include obscured star-forming galaxies at 1.4 < z < 2.5, it is possible that the submm galaxies are a sub-group of BzKs. We identified 4 BzKs as submm galaxies within 93 arcmin2 by using high resolution radio images. This indicates that only ~20% of submm galaxies are BzKs. However, this fraction is consistent with the assumption that the most of submm galaxies at 1.4 < z < 2.5 are BzKs, considering the redshift distribution, radio-detection rate and observed K-band magnitudes of submm galaxies. We found no submm detections for EROs which are clearly non-BzKs. We identify two submm-bright NIR-selected galaxies, which satisfy all the selection criteria we adopt; i.e. they belong to the BzK-DRG-ERO overlapping population, or ‘extremely red’ BzKs. Although these extremely red BzKs are rare (0.25 arcmin−2), about 10% of this population could be submm galaxies. With a stacking analysis, we detected the 850-μm flux of submm-faint BzKs and EROs in our SCUBA maps. While the contribution from BzKs at z ~ 2 to submm background is about 10–15% and similar to that from EROs typically at z ~ 1, BzKs have a higher fraction (~30%) of submm flux in resolved sources than EROs and submm sources as a whole do. Therefore, submm flux of BzKs seems to be biased high. From the SED fitting using an evolutionary model of starbursts with radiative transfer, submm-bright BzKs are found to have the stellar mass of >5 × 1010M⊙ with the luminosity of >3 × 1012L⊙. From an average SED of submm-faint BzKs having similar B − z and z − K colours to submm-bright ones, we suggest that submm-bright BzKs are more massive than submm-faint ones.
New submillimeter diagnostics of physical properties of ISM in high redshift galaxies
Authors: Tamura Yoichi , Nakanishi Kouichiro , Kohno Kotaro , Kawabe Ryohei 
Published: April 2007

AbstractWe present a new diagnosis method for determining physical properties of star-forming gas in high-z galaxies. In this method, we employed three key observational quantities, [CI], CO, and FIR luminosities, including our new detections of CO J = 4–3 emission from the pure-starburst (non-AGN) submm galaxy SMM J14011+0252 (z = 2.6) and the type-2 AGN IRAS FSC 10214+4724 (z = 2.3) obtained with the Nobeyama Millimeter Array (NMA) at the Nobeyama Radio Observatory. These two sources have extremely high star formation rate, and exhibit strong emission of CO and [CI] 609 μm lines. We determined ISM physical conditions for the two objects and another three high-z quasars in order to investigate the relationship between their ISM and power sources (i.e., massive star formation or AGN). A new PDR analysis (Wolfire et al. 2005, private communication) using CO, [CI], and FIR on five high-z sources provides new evidence that AGN host galaxies harbor denser (log nH ~ 5–6) ISM exposed to stronger far-UV fluxes of log G0 ~ 3.5–4 than the non-AGN submm galaxy. Volume filling factors of the star-forming dense gas in the AGN hosts are an order of magnitude smaller than that of the pure-starburst submm galaxy. This suggests that, in these AGN hosts, dense molecular clouds are dominating the central kpc around AGN, triggering extensive circumnuclear starbursts, and possibly feeding their central supermassive black hole simultaneously.
RC J0311+0507: A Candidate to Superpowerful Radio Galaxies with z = 4.514
Authors: Kopylov A. I. , Parijskij Yu. N. , Soboleva N. S. , Temirova A. V. , Verkhodanov O. V. , Goss W. M. , Zhelenkova O. P. 
Published: April 2007

AbstractThe investigations of the ultra steep spectrum radio source RC J0311+0507 (4C+04.11) in radio (RATAN-600, VLA) and optics (6-m telescope SAO RAS) are presented. The identification of a strong line at 6703 Å with Lyα gives a redshift z=4.514. The object belongs to the group of extremely distant radio galaxies of ultrahigh radio luminosity (P1400 = 1.3 × 1029WHz−1).
NIR Follow-Up of the VVDS 02hr Field: First Results
Authors: Temporin S. , Iovino A. , McCracken H. J. , Bolzonella M. , Scodeggio M. ,   the VVDS Team
Published: April 2007

AbstractWe present a new K-band survey covering 623 arcmin2 in the VVDS 0226-0430 deep field down to a limiting magnitude KVega ≤ 20.5. We use the spectroscopic sample extracted from this new K-band catalogue to assess the effectiveness of optical-near infrared color selections in identifying extreme classes of objects at high redshift.
The Impact of Stochastic Attenuation on Photometric Redshift Estimates
Authors: García Thorsten Tepper , Alvensleben Uta Fritze-von 
Published: April 2007

AbstractWe model the stochastic attenuation by HI absorbers in the intergalactic medium (IGM), such as Lyα Forest clouds, and absorbers associated with galaxies, such as Lyman Limit systems (LLS) and Damped Lyman Alpha absorbers (DLAs), and compute an ensemble of 4 · 103 attenuated Spectral Energy Distributions (SEDs) in the Johnson system for the spectrum of a galaxy with a constant star formation rate (CSFR). Using these, we asses the impact of the stochastic attenuation on the estimates of photometric redshifts for this type of galaxy by comparison with model SEDs that include only a mean attenuation.
The Evolution of Neutral Gas in the Universe
Authors: Turnshek David , Rao Sandhya , Monier Eric , Nestor Daniel , Quider Anna 
Published: April 2007

AbstractWe give references to some of our work on the properties and evolution of the neutral gas component of the Universe (see reference list). The bulk of the observed neutral gas has been detected by identifying intervening damped Lyα (DLA) quasar absorption-line systems with N(H) ≥2 × 1020 atoms cm−2. We also present some initial results from a program to identify DLA absorbers near redshift z = 0.5 using Hubble Space Telescope ACS prism spectra (see Figure 1).
Turbulence in the molecular interstellar medium
Authors: Heyer Mark H. , Brunt Chris 
Published: April 2007

AbstractThe observational record of turbulence within the molecular gas phase of the interstellar medium is summarized. We briefly review the analysis methods used to recover the velocity structure function from spectroscopic imaging and the application of these tools on sets of cloud data. These studies identify a near-invariant velocity structure function that is independent of the local environment and star formation activity. Such universality accounts for the cloud-to-cloud scaling law between the global line-width and size of molecular clouds found by Larson (1981) and constrains the degree to which supersonic turbulence can regulate star formation. In addition, the evidence for large scale driving sources necessary to sustain supersonic flows is summarized.
The turbulent environment of low-mass dense cores
Authors: Falgarone E. , Hily-Blant P. , Pety J. , des Forêts G. Pineau 
Published: April 2007

AbstractThe signatures of intermittent dissipation of turbulent energy have been sought in the translucent environment of a low-mass dense core. Molecular line observations reveal a network of narrow filamentary structures, found on statistical grounds to be the locus of the largest velocity shears. Three independent properties of these structures make them the plausible sites of intermittent dissipation of turbulence: (1) gas there is warmer and more diluted than average, (2) it bears the signatures of a non-equilibrium chemistry triggered by impulsive heating due to turbulence dissipation, and (3) the power that these structures radiate in the gas cooling lines (mostly H2) is so large that it balances the total energy injection rate of the turbulent cascade, for a volume filling factor of only a few percents, consistent with other observations in the Solar Neighborhood. These filamentary structures may act as tiny seeds of gas condensation in diffuse molecular gas. They do not exhibit the properties of steady-state low-velocity magneto-hydrodynamic (MHD) shocks, as presently modelled.
CO, HI, recent Spitzer SAGE results in the Large Magellanic Cloud
Authors: Fukui Yasuo 
Published: April 2007

AbstractFormation of GMCs is one of the most crucial issues in galaxy evolution. I will compare CO and HI in the LMC in 3 dimensional space for the first time aiming at revealing the physical connection between GMCs and associated HI gas at a ~40 pc scale. The present major findings are 1) [total CO intensity] ∝ [total HI intensity]0.8 for the 110 GMCs, and 2) the HI intensity tends to increase with the evolution of GMCs. I argue that these findings are consistent with the growth of GMCs via HI accretion over a time scale of a few × 10 Myrs. I will also discuss the role of the background stellar gravity and the dynamical compression by supershells in formation of GMCs.
Dense molecular clouds and associated star formation in the Magellanic Clouds
Authors: Rubio Mónica 
Published: April 2007

AbstractMultiwavelengths studies of massive star formation regions in the LMC and SMC reveal that a second generation of stars is being formed in dense molecular clouds located in the surroundings of the massive clusters. These dense molecular clouds have survived the action of massive star UV radiation fields and winds and they appear as compact dense H2 knots in regions of weak CO emission. Alternatively, we have found that large molecular clouds, probably remnants of the parental giant molecular clouds where the first generation of stars were formed, are suffering the interaction of the winds and UV radiation field in their surfaces in the direction of the central massive cluster or massive stars. These molecular regions show 1.2 mm continuum emission form cold dust and they show embedded IR sources as determined from deep ground base JHKs imaging. The distribution of young IR sources as determined from their Mid IR colors obtained by SPITZER concentrate in the maxima of CO and dust emission. IR spectroscopy of the embedded sources with high IR excess confirm their nature as massive young stellar objects (MYSO's). Our results are suggestive of contagious star formation where triggering and induced star formation could be taking place.
Dust evolution in the star forming turbulent interstellar medium
Authors: Boulanger François 
Published: April 2007

AbstractUnderstanding interstellar dust evolution is a major challenge underlying the interpretation of Spitzer observations of interstellar clouds, star forming regions and galaxies. I illustrate on-going work along two directions. I outline the potential impact of interstellar turbulence on the abundance of small dust particles in the diffuse interstellar medium and translucent sections of molecular clouds. I present results from an analysis of ISO and Spitzer observations of the central part of 30 Doradus, looking for dust evolution related to the radiative and dynamical impact of the R136 super star cluster on its parent molecular cloud.
New results on the distribution of thermal pressures in the diffuse ISM
Authors: Jenkins Edward B. , Tripp Todd M. 
Published: April 2007

AbstractThe ground electronic state of neutral atomic carbon has three fine-structure levels. In the interstellar medium, the relative populations of the upper two levels are established by collisional excitations (and de-excitations) balanced against spontaneous radiative decay. Consequently, the fractions of C I in the upper two levels indicate acceptable combinations of local temperature and density, which in turn indicate the approximate thermal pressures of the medium. We can measure the values of these fractions and how they vary from one location to the next by observing the multiplets of C I seen in absorption in the ultraviolet spectra of hot stars.We have identified 102 stars for which the HST MAST archive has E140H STIS spectra that are suitable for measuring the absorption features of C I at velocity resolutions of 3 kms−1(or better). A special analysis method developed by Jenkins & Tripp (2001) permits determinations of the amounts of C I in each of the three levels as a function of radial velocity over a wide dynamic range in column density, since several multiplets of vastly different strengths can be considered simultaneously.The C I data reveal that the much of the diffuse, cold, neutral medium has pressures that are distributed in an approximately log-normal fashion, spread over a range 1000 < p/k < 104 cm−3 K (FWHM), but with low level tails outside this range. The dispersion of pressures increases slightly for gases that have radial velocities outside the expected range for quiescent material along each line of sight. This link to the kinematics of the gas is consistent with the picture that pressure fluctuations are driven by the dynamics of a turbulent medium. If the gas is a single medium that is being driven by turbulent forces, its barytropic index (slope of log p vs. log n) is more than 0.9, which is inconsistent with the value 0.72 for material that is expected to be in thermal equilibrium. Slightly less than one part in a thousand of the gas is at pressures of order or greater than ~105cm−3 K and seems to nearly always accompany the gas at normal pressures.
Dynamical evolution of a supernova driven turbulent interstellar medium
Authors: Breitschwerdt Dieter , de Avillez Miguel A. 
Published: April 2007

AbstractIt is shown that a number of key observations of the Galactic ISM can be understood, if it is treated as a highly compressible and turbulent medium, energized predominantly by supernova explosions (and stellar winds). We have performed extensive numerical high resolution 3D hydrodynamical and magnetohydrodynamical simulations with adaptive mesh refinement over sufficiently long time scales to erase memory effects of the initial setup. Our results show, in good agreement with observations, that (i) volume filling factors of the hot medium are modest (typically below 20%), (ii) global pressure is far from uniform due to supersonic (and to some extent super-Alfvénic) turbulence, (iii) a significant fraction of the mass (~60%) in the warm neutral medium is in the thermally unstable regime (500 < T < 5000 K), (iv) the average number density of Ovi in absorption is 1.81 × 10−8 cm−3, in excellent agreement with Copernicus and FUSE data, and its distribution is rather clumpy, consistent with its measured dispersion with distance.
ISM turbulence driven by the magnetorotational instability
Authors: Piontek Robert A. , Ostriker Eve C. 
Published: April 2007

AbstractWe have performed numerical simulations which were designed to further our understanding of the turbulent interstellar medium (ISM). Our simulations include a multi-phase thermodynamic model of the ISM, magnetic fields, and sheared rotation, allowing us to study the effects of the magnetorotational instability (MRI) in an environment containing high density cold clouds embedded in a warm, low density, ambient medium. These models have shown that the MRI is indeed a significant source of turbulence, particularly at low mean densities typical of the outer regions of the Milky Way, where star formation rates are low, but high levels of turbulence persist. Here, we summarize past findings, as well as our most recent models which include vertical stratification, allowing us to self-consistently model the vertical distribution of material in the disk.
Non-stellar sources of turbulence in the interstellar medium
Authors: Ostriker Eve C. 
Published: April 2007

AbstractTurbulence is believed to be important to star formation both within GMCs (affecting the IMF and the SFE), and on larger scales in the ISM (affecting GMC formation rates and properties). The traditional view of the ISM attributes most of the turbulent driving to stellar sources – in particular, supernovae and HII regions. However, evidence suggests that sources other than star formation must contribute significantly to large-scale turbulent driving in the diffuse ISM, thus also affecting the turbulence that GMCs inherit. I review recent investigations of alternative sources proposed for driving ISM turbulence, including thermal instabilities, the magnetorotational instability, large-scale self-gravitating modes, and instabilities in spiral shocks. I summarize results based on numerical simulations regarding the levels of turbulence that can be driven, and how these amplitudes depend on galactic conditions. This recent work shows that, under certain circumstances, very large-amplitude (trans-sonic with respect to the warm gas) motions and magnetic fields can be driven even without stellar energy inputs. Since turbulence can either trigger or limit star formation, understanding these potentially large non-stellar driving sources is crucial for a developing a theory of star formation regulation in the Milky Way and other disk galaxies.
Observations of supershells in the interstellar medium of nearby galaxies
Authors: Brinks Elias , Bagetakos Ioannis , Walter Fabian , de Blok Erwin 
Published: April 2007

AbstractHI observations at sufficiently high spatial and velocity resolution have revealed a wealth of structures such as shells and bubbles in the ISM of late–type galaxies. These structures are filled with metal–enriched, coronal gas from SNe which, through overpressure, powers their expansion. Material swept up by these expanding shells can go “critical” and form subsequent (secondary or propagating) star formation. Shells that grow larger than the thickness of the gas layer will blow out of the disk, spilling enriched material into the halo (or in the case of violent starbursts, the Intergalactic Medium). We review what has been achieved to date and present some first results of a major project based on THINGS (The HI Nearby Galaxy Survey), which aims to extend studies of the ISM in galaxies to 34 nearby systems (<10 Mpc), all observed to the same exacting standards (resolution 6″ × 5 km s−1, or better; typical detection threshold of ~5 × 1019 atom cm−2).
Shells in the Magellanic System
Authors: Stanimirović Snežana 
Published: April 2007

AbstractThe Magellanic System harbors >800 expanding shells of neutral hydrogen, providing a unique opportunity for statistical investigations. Most of these shells are surprisingly young, 2–10 Myr old, and correlate poorly with young stellar populations. I summarize what we have learned about shell properties and particularly focus on the puzzling correlation between the shell radius and expansion velocity. In the framework of the standard, adiabatic model for shell evolution this tight correlation suggests a coherent burst of star formation across the whole Magellanic System. However, more than one mechanism for shell formation may be taking place.
An automatic identification of HI shells in the 2nd and 3rd Galactic Quadrants
Authors: Ehlerová Soňa 
Published: April 2007

AbstractWe briefly discuss different methods used to identify HI shells in TB datacubes. Then we give results for our automatic method applied to LDS and LAB HI surveys of the Milky Way (2nd and 3rd quadrants). We fit the radial distribution of HI shells (the exponential profile with the scale length of 3 kpc) and the size distribution (the power law with the index of 2.1). We compare the distribution of identified HI shells with HII regions and study the differences between identifications in the 2nd and 3rd quadrants.
The SMC super-shells as probes of the turbulent dynamics of the ISM
Authors: Goldman Itzhak 
Published: April 2007

AbstractThe spatial power spectrum of the HI 21 cm intensity in the Small Magellanic Cloud (Stanimirovic et al. 1999) is a power law over scales as large as those of the SMC itself. It was interpreted as due to turbulence by Goldman (2000) and by Stanimirovic & Lazarian (2001). The question is whether the power spectrum is indeed the result of a dynamical turbulence or is merely the result of a structured static density. In the turbulence interpretation of Goldman (2000) the turbulence was generated by the tidal effects of the last close passage of the LMC about 0.2 Gyr ago. The turbulence time-scale was estimated by Goldman to be 0.4 Gyr, so the turbulence has not decayed yet. Staveley-Smith et al. (1997) observed in the SMC about five hundreds of HI super shells. Their age is more than an order of magnitude smaller than the turbulence age. Therefore, if the turbulence explanation holds, their observed radial velocities should reflect the turbulence in the gas in which they formed. In the present work we analyze the observed radial velocities of the super shells. We find that the velocities indeed manifest the statistical spatial correlations expected from turbulence. The turbulence spectrum is consistent with that obtained by Goldman (2000).