We have modeled a large sample of infrared starburst galaxies using both the PEGASE v2.0 and STARBURST99 codes to generate the spectral energy distribution (SED) of the young star clusters. PEGASE utilizes the Padova group tracks, while STARBURST99 uses the Geneva group tracks, allowing comparison between the two. We used our MAPPINGS III code to compute photoionization models that include a self-consistent treatment of dust physics and chemical depletion. We use the standard optical diagnostic diagrams as indicators of the hardness of the EUV radiation field in these galaxies. These diagnostic diagrams are most sensitive to the spectral index of the ionizing radiation field in the 1-4 ryd region. We find that warm infrared starburst galaxies contain a relatively hard EUV field in this region. The PEGASE ionizing stellar continuum is harder in the 1-4 ryd range than that of STARBURST99. As the spectrum in this regime is dominated by emission from Wolf-Rayet (W-R) stars, this discrepancy is most likely due to the differences in stellar atmosphere models used for the W-R stars. The PEGASE models use the Clegg & Middlemass planetary nebula nuclei (PNN) atmosphere models for the W-R stars, whereas the STARBURST99 models use the Schmutz, Leitherer, & Gruenwald W-R atmosphere models. We believe that the Schmutz et al. atmospheres are more applicable to the starburst galaxies in our sample; however, they do not produce the hard EUV field in the 1-4 ryd region required by our observations. The inclusion of continuum metal blanketing in the models may be one solution. Supernova remnant (SNR) shock modeling shows that the contribution by mechanical energy from SNRs to the photoionization models is 20%. The models presented here are used to derive a new theoretical classification scheme for starbursts and active galactic nucleus (AGN) galaxies based on the optical diagnostic diagrams.

https://iopscience.iop.org/article/10.1086/321545/pdf

Theoretical Modeling of Starburst Galaxies

1 Introduction 2 Models: the QCD axion; the strong CP problem; PQWW, KSVZ, DFSZ; anomalies, instantons and the potential; couplings; axions in string theory 3 Production and IC's: SSB and non-perturbative physics; the axion field during inflation and PQ SSB; cosmological populations - decay of parent, topological defects, thermal production, vacuum realignment 4 The Cosmological Field: action; background evolution; misalignment for QCD axion and ALPs; cosmological perturbation theory - ic's, early time treatment, axion sound speed and Jeans scale, transfer functions and WDM; the Schrodinger picture; simualting axions; BEC 5 CMB and LSS: Primary anisotropies; matter power; combined constraints; Isocurvature and inflation 6 Galaxy Formation; halo mass function; high-z and the EOR; density profiles; the CDM small-scale crises 7 Accelerated expansion: the cc problem; axion inflation (natural and monodromy) 8 Gravitational interactions with black holes and pulsars 9 Non-gravitational interactions: stellar astrophysics; LSW; vacuum birefringence; axion forces; direct detection with ADMX and CASPEr; Axion decays; dark radiation; astrophysical magnetic fields; cosmological birefringence 10 Conclusions A Theta vacua of gauge theories B EFT for cosmologists C Friedmann equations D Cosmological fluids E Bayes Theorem and priors F Degeneracies and sampling G Sheth-Tormen HMF

Axion Cosmology

HCN luminosity is a tracer of dense molecular gas, n(H(2)) greater than or similar to3 x 10(4) cm(-3), associated with star-forming giant molecular cloud (GMC) cores. We present the results and analysis of our survey of HCN emission from 65 infrared galaxies, including nine ultraluminous infrared galaxies (ULIGs, L(IR) greater than or similar to 10(12) L(circle dot)), 22 luminous infrared galaxies (LIGs, 10(11) L(circle dot) < L(IR) less than or similar to 10(12) L(circle dot)), and 34 normal spiral galaxies with lower IR luminosity (most are large spiral galaxies). We have measured the global HCN line luminosity, and the observations are reported in Paper I. This paper analyzes the relationships between the total far-IR luminosity (a tracer of the star formation rate), the global HCN line luminosity (a measure of the total dense molecular gas content), and the CO luminosity (a measure of the total molecular content). We find a tight linear correlation between the IR and HCN luminosities L(IR) and L(HCN) (in the log-log plot) with a correlation coefficient R = 0.94, and an almost constant average ratio L(IR)/L(HCN) = 900 L(circle dot) (K km s(-1) pc(2))(-1). The IR-HCN linear correlation is valid over 3 orders of magnitude including ULIGs, the most luminous objects in the local universe. The direct consequence of the linear IR-HCN correlation is that the star formation law in terms of dense molecular gas content has a power-law index of 1.0. The global star formation rate is linearly proportional to the mass of dense molecular gas in normal spiral galaxies, LIGs, and ULIGs. This is strong evidence in favor of star formation as the power source in ultraluminous galaxies since the star formation in these galaxies appears to be normal and expected given their high mass of dense star-forming molecular gas.

https://iopscience.iop.org/article/10.1086/382999/pdf

The Star Formation Rate and Dense Molecular Gas in Galaxies

Learning how to control the formation and twoand three-dimensional assembly of molecular scale building blocks into well-defined mesoand macroscopic structures is the essence of nanotechnology and materials chemistry. DNA is arguably one of the most programmable “assemblers” available to the synthetic chemist and materials scientist, yet until recently, it has been an underutilized synthon in materials chemistry. The purpose of this review is to summarize advances made involving new strategies that rely on the use of both naturally occurring DNA and synthetic oligonucleotides to assemble nanoscale nonbiological building blocks into extended mesoand macroscopic structures. Although early in their development, some of these strategies already have been shown to be useful in generating novel nanostructured materials,1-4 arranging inorganic nanoparticles into “anatural” configurations,5,6 understanding interparticle electronic interactions,1 templating the growth of nanocircuitry,7 and developing a promising new detection technology for DNA.8,9 There are two basic types of building blocks that are applicable to a variety of assembly schemes: molecules with synthetically programmed recognition sites or bits of matter with nanoscale dimensions and well-defined surface chemistries. The latter type of building block is often referred to as a “nanoparticle” or “nanocrystal”. Assembly of such building blocks into extended, well-defined structures can provide a variety of functional materials with applications including ultrasmall electronic devices,10-13 spectroscopic enhancers,14,15 high-density information storage media,16,17 and highly sensitive and selective chemical detectors.8,9,18 The assembly of nanoparticle and molecular building blocks into functional structures has been accomplished through both physical and chemical methods.19 Physical methods include the use of scanning probe microscopy,20-22 electrophoretic strategies,23,24 LB films,25,26 or templatedriven sedimentation27 to position particles in a preconceived fashion within a matrix or on a substrate. Although effective for preparing certain types of nanoscale architectures, many of these physical methods are limited because they are often slow and do not lend themselves to preparing designed nanostructured architectures that canvas macroscopic dimensions. Chemical methods include ordering particles based upon interparticle electrostatic interactions,28-30 covalent assembly,31,32 template recognition,33,34 template recognition with subsequent covalent cross-linking reactions,35,36 crystallization based upon weak intermolecular interactions,37-41 or linking reactions involving designed organic or biological recognition sites.1,2,4,42 The advantages of chemical methods are that building block linking processes can occur in a massively parallel fashion and in some cases possess self-annealing or correcting properties. This makes them particularly attractive for constructing twoand three-dimensional structures on a faster time scale. The disadvantage is that at present chemical methods, when compared with some of the aforementioned physical deposition methods, are difficult to control. Recently, there has been substantial interest in utilizing biomolecules to direct the formation of extended mesoand macroscopic architectures.43,44 The advantage of using biomolecules is that molecular recognition is already built into the building block of interest (e.g., peptides, oligonucleotides, and proteins). In some cases, synthetic versions of the biomolecules are readily available and easily adaptable to both inorganic and organic building blocks and substrates.45 This review examines the use of one class of these biomolecules, DNA, to organize nanometer-sized structures into preconceived extended, functional structures and materials. It is divided into three categories; the use of (1) oligonucleotides (singlestranded DNA) to prepare mesoand macroscopic organic structures, (2) duplex DNA as a physical template for growing inorganic wires and organizing nonbiological building blocks into extended hybrid materials, and (3) oligonucleotide functionalized nanoparticles and sequence-specific hybridization reactions for organizing such particles into periodic, functional structures. 1849 Chem. Rev. 1999, 99, 1849−1862

Programmed Materials Synthesis with DNA.

Clusters of galaxies, as the largest virialized systems in the Universe, are ideal laboratories to study the formation and evolution of cosmic structures. The luminous matter of clusters consists of galaxies and of an embedding intracluster medium (ICM), which has been heated to temperatures of tens of millions degrees, and thus is detected through its thermal emission in the soft X-ray regime. Most of the detailed knowledge of galaxy clusters has been obtained in recent years from the study of ICM through X-ray Astronomy. At the same time, radio observations have proved that the ICM is mixed with non-thermal components, i.e. highly relativistic particles and large-scale magnetic fields, detected through their synchrotron emission. The knowledge of the properties of these non-thermal ICM components has increased significantly, owing to sensitive radio images and to the development of theoretical models. Diffuse synchrotron radio emission in the central and peripheral cluster regions has been found in many clusters. Moreover large-scale magnetic fields appear to be present in all galaxy clusters, as derived from Rotation Measure (RM) studies. Non-thermal components are linked to the cluster X-ray properties, and to the cluster evolutionary stage, and are crucial for a comprehensive physical description of the intracluster medium. They play an important role in the cluster formation and evolution. We review here the observational properties of diffuse non-thermal sources detected in galaxy clusters: halos, relics and mini-halos. We discuss their classification and properties. We report published results up to date and obtain and discuss statistical properties. We present the properties of large-scale magnetic fields in clusters and in even larger structures: filaments connecting galaxy clusters. We summarize the current models of the origin of these cluster components, and outline the improvements that are expected in this area from future developments thanks to the new generation of radio telescopes.

/pdf/clusters-of-galaxies-observational-properties-of-the-diffuse-2s1qx72cld.pdf

Clusters of galaxies: observational properties of the diffuse radio emission

The central region of the Coma cluster of galaxies was observed in the energy band from 0.065 to 0.245 kiloelectron volts by the Deep Survey telescope aboard the Extreme Ultraviolet Explorer. A diffuse emission halo of angular diameter ∼30 arc minutes was detected. The extreme-ultraviolet (EUV) emission level exceeds that expected from the x-ray temperature gas in Coma. This halo suggests the presence of two more phases in the emitting gas, one at a temperature of ∼2 × 10 6 kelvin and the other at ∼8 × 10 5 kelvin. The latter phase cools rapidly and, in steady state, would have produced cold matter with a mass of ∼10 14 solar masses within the EUV halo. Although a similar EUV enhancement was discovered in the Virgo cluster, this detection in Coma applies to a noncooling flow system.

http://science.sciencemag.org/content/sci/274/5291/1335.full.pdf

Diffuse Extreme-Ultraviolet Emission from the Coma Cluster: Evidence for Rapidly Cooling Gases at Submegakelvin Temperatures

An observation of M87, the central galaxy of the Virgo Cluster, was performed by the deep survey telescope aboard the Extreme-Ultraviolet Explorer, in the 0.065-0.245 keV energy band. A point source and an extended emission halo of radius ~20' are clearly visible in the data, and represent the first detection of cluster gas emission in the EUV. The emission cannot be explained by the well-known cluster gas at X-ray temperatures. Instead, it is necessary to introduce a second gas component, with temperature between 5 × 105 and 106 K. The rapid cooling of plasmas at such temperatures implies a mass accretion rate of more than 300 M☉ yr-1. It is unlikely that the phenomenon is directly related to a cooling flow, which involves a much lower accretion rate of ~10 M☉ yr-1.

Discovery of 0.5 MK Gas in the Center of the Virgo Cluster

Matter and Energy in Clusters of Galaxies

The excess extreme-ultraviolet (EUV) emission detected in the Virgo and Coma clusters is explained by inverse Compton scattering of cosmic microwave background photons, which are scattered by the relativistic electrons that account for the extended radio synchrotron emission of these clusters. The lower limits of the average magnetic fields of these clusters estimated from the EUV excess are close to the equipartition magnetic fields derived from radio observations, indicating that the electron energies and magnetic field energies might be close to equipartition. The excess emission suggests energy reservoirs of ∼1061 and ∼1060 ergs for the Coma and Virgo clusters, respectively.

http://science.sciencemag.org/content/sci/278/5345/1917.full.pdf

An Inverse Compton Process for the Excess Diffuse EUV Emission from the Virgo and Coma Galaxy Clusters

We present CO(3-2) interferometric observations of the central region of the Seyfert 2 galaxy NGC 1068 using the Submillimeter Array, together with CO(1-0) data taken with the Owens Valley Radio Observatory Millimeter Array. Both the CO(3-2) and CO(1-0) emission lines are mainly distributed within {approx}5 arcsec of the nucleus and along the spiral arms, but the intensity distributions show differences: the CO(3-2) map peaks in the nucleus, while the CO(1-0) emission is mainly located along the spiral arms. The CO(3-2)/CO(1-0) ratio is about 3.1 in the nucleus, which is four times as large as the average line ratio in the spiral arms, suggesting that the molecular gas there must be affected by the radiation arising from the active galactic nucleus. On the other hand, the line ratios in the spiral arms vary over a wide range from 0.24 to 2.34 with an average value around 0.75, which is similar to the line ratios of star formation regions, indicating that the molecular gas is affected by star formation. Besides, we see a tight correlation between CO(3-2)/(1-0) ratios in the spiral arms and star formation rate surface densities derived from Spitzer 8 {mu}m dust flux densities. We also compare the CO(3-2)/(1-0) ratiomore » and the star formation rate at different positions within the spiral arms; both are found to decrease as the radius from the nucleus increases.« less

Chorng Yuan Hwang

Papers

Diffuse Extreme-Ultraviolet Emission from the Coma Cluster: Evidence for Rapidly Cooling Gases at Submegakelvin Temperatures

Discovery of 0.5 MK Gas in the Center of the Virgo Cluster

Matter and Energy in Clusters of Galaxies

An Inverse Compton Process for the Excess Diffuse EUV Emission from the Virgo and Coma Galaxy Clusters

Interferometric CO(3?2) Observations toward the Central Region of NGC?1068