Current star-forming galaxies (SFGs) with CO measurements at z ~ 2 suffer from a bias toward high star formation rates (SFR) and high stellar masses (M*). It is yet essential to extend the CO measurements to the more numerous z ~ 2 SFGs with LIR < L⋆ = 4× 1011 L⊙ and M* < 2.5× 1010 M⊙. We have achieved CO, stars, and dust measurements in 8 such sub-L⋆ SFGs with the help of gravitational lensing. Combined with CO-detected galaxies from the literature, we find that the LIR, L′CO(1−0) data are best-fitted with a single relation that favours a universal star formation. This picture emerges because of the enlarged star formation efficiency spread of the current z>1 SFGs sample. We show that this spread is mostly triggered by the combination of redshift, specific SFR, and M*. Finally, we find evidence for a non-universal dust-to-gas ratio (DGR) with a clear trend for a lower DGR mean in z>1 SFGs by a factor of 2 with respect to local galaxies and high-redshift sub-mm galaxies at fixed about solar metallicity.

We present an updated status of the EDGE project, which is a survey of 125 local galaxies in the 12CO(1−0) and 13CO(1−0) lines. We combine the molecular data of the EDGE survey with the stellar and ionized gas maps of the CALIFA survey to give a comprehensive view of the dependence of the star formation efficiency, or equivalently, the molecular gas depletion time, on various local environments, such as the stellar surface density, metallicity, and radius from the galaxy center. This study will provide insight into the parameters that drive the star formation efficiency in galaxies at z ~ 0.

We investigate the sputtering and thermal desorption of various grain-surface species in one dimensional steady-state shock models motivated by the recent detection of SO emission towards class 0-I protostars. We find that the thermal desorption is more efficient at higher densities, while the efficiency of sputtering is independent of density. SO is completely desorbed, if the accretion velocity is higher than ~ 2 km s−1 and ~ 4 km s−1, with the pre-shock density of 109 cm−3 and 108 cm−3, respectively. The column density of warm post-shock gas is found to be N ~ 1021 cm−2. If the abundance of SO ice is ~ 10−7 relative to hydrogen in the pre-shock material, SO emission around L1527 can be explained by the sublimation at the accretion shock.

Massive stars are some of the most important objects in the Universe, shaping the evolution of galaxies, creating chemical elements, and hence shaping the evolution of the Universe. However, the processes by which they form, and how they shape their environment during their birth processes, are not well understood. We are using NH3 data from the “The H2O Southern Galactic Plane Survey” (HOPS) to define the positions of dense cores/clumps of gas in the southern Galactic plane that are likely to form stars. We did a comparative study with different methods for finding clumps and found Fellwalker to be the best for this dataset. We detected ~ 500 clumps with mean kinetic temperature ~ 20 K and virial mass ~ 680 solar masses.

Gas and dust grains are fundamental components of the interstellar medium and significantly impact many of the physical processes driving galaxy evolution, such as star-formation, and the heating, cooling, and ionization of the interstellar material. Quasar absorption systems (QASs), which trace intervening galaxies along the sightlines to luminous quasars, provide a valuable tool to directly study the properties of the interstellar gas and dust in distant, normal galaxies. We have established the presence of silicate dust grains in at least some gas-rich QASs, and find that they exist at higher optical depths than expected for diffuse gas in the Milky Way. Differences in the absorption feature shapes additionally suggest variations in the silicate dust grain properties, such as in the level of grain crystallinity, from system-to-system. We present results from a study of the gas and dust properties of QASs with adequate archival IR data to probe the silicate dust grain properties. We discuss our measurements of the strengths of the 10 and 18 μm silicate dust absorption features in the QASs, and constraints on the grain properties (e.g., composition, shape, crystallinity) based on fitted silicate profile templates. We investigate correlations between silicate dust abundance, reddening, and gas metallicity, which will yield valuable insights into the history of star formation and chemical enrichment in galaxies.

We studied the unbiased optical brightness distribution which was calculated from the survival analysis of host galaxies (HGs) data and its relationship with the Swift GRB data of the host galaxies observed by the Keck telescope. Based on the sample obtained from merging the Swift GRB table and the Keck optical data we also studied the dependence of this distribution on the GRB's data. Finally, we compared the HGs distribution with standard galaxies distribution of the DEEP2 redshift survey and checked the result with the VIPERS catalogue too.

We present the Three-mm Ultimate Mopra Milky Way Survey, a new mm-wave molecular-line mapping survey of the southern Galactic Plane, and its first data releases and science results. ThrUMMS maps a 60° × 2° sector of our Galaxy's fourth quadrant, using a combination of fast mapping techniques with the Mopra radio telescope, simultaneously in the J = 1→0 lines of 12CO, 13CO, C18O, and CN near 112 GHz, at 1′.2 and 0.3 km s−1 resolution, with 1.2 K/ch sensitivity for 12CO and 0.7 K/ch for the other transitions. The calibrated data cubes from these observations are made freely available to the community on the ThrUMMS website, http://www.astro.ufl.edu/thrumms, after processing through our pipeline. Here, we summarise the first science results, on global variations in the iso-CO line ratios and on a detailed multiwavelength study of the GMCs near l=333°.

We present a model for the seeding and evolution of magnetic fields in galaxies by supernovae (SN). SN explosions during galaxy assembly provide seed fields, which are subsequently amplified by compression, shear flows and random motions. Our model explains the origin of μG magnetic fields within galactic structures. We implement our model in the MHD version of the cosmological simulation code Gadget-3 and couple it with a multi-phase description of the interstellar medium. We perform simulations of Milky Way-like galactic halo formation and analyze the distribution and strength of the magnetic field. We investigate the intrinsic rotation measure (RM) evolution and find RM values exceeding 1000 rad/m2 at high redshifts and RM values around 10 rad/m2 at present-day. We compare our simulations to a limited set of observational data points and find encouraging similarities. In our model, galactic magnetic fields are a natural consequence of the very basic processes of star formation and galaxy assembly.

We present a new method (BUBBLY) for detecting expanding components of ionized gas using integral field spectroscopy, showing its capabilities not only in detecting but also in obtaining the key physical parameters of the expanding shells: their expansion velocities and masses. The main advantages are that the detection is performed automatically via software and that we can derive most parameters of the shells, so it is suitable for detailed studies of feedback in nearby galaxies. The software can easily be configured to run on any data cube mapping an emission line over a spatial field. We also present results obtained by running BUBBLY on observations of Hα emission with the Fabry-Perot spectrograph GHαFaS: two sets of spectacular results at widely different spatial scales: the Antennae galaxies show multiple giant bubbles of size ~300pc around the brightest clusters, while inside a region in M33 we find three nested supernova remnants, with which we can study the feedback on the molecular gas surrounding the cluster.

We report on our ongoing project “Statistical studies of HII regions in the nearby extra-galaxies”. We present an overview of our detailed study of warm dust in the nearby Galaxy NGC 4321 (M100), measuring the flux values in the 4 Spitzer-IRAC bands of some 275 HII regions in M100. In addition, we present new measurements of the flux values in the 4 Spitzer-IRAC bands of a complete sample of 70 isolated luminous HII regions in NGC 4736 and 157 regions in NGC 4254. We study the relations between the Hα luminosity and the near-IR luminosity and temperature of HII regions in the three galaxies. We estimate the near-IR luminosities and compare them with the Hα luminosities from archive and literature sources. We find a linear relation between the Hα luminosity and the IRAC luminosity for the HII regions, but no apparent relation between the luminosity and the colour temperature of the regions in any of the three galaxies. The colour temperatures of regions especially in M100 and NGC4254 are confined to a surprisingly narrow range, with a small fraction forming a higher temperature tail to the distribution. These results give new insight into the size function and the 3D distribution of the dust in these regions, and we propose scenarios to explain them.

We present a set of time dependent chemical evolution models (based on the UMIST† astrochemistry 2012 code, Woodall et al. (2007); McElroy et al. (2013) for a range of initial physical cloud parameters: 10 K < T < 20 K; 103 cm−3 < n(H2) < 5 · 104 cm−3; 1 < AV < 10 and with estimated values of scaled interstellar ultraviolet radiation field. Our computation model included the full UMIST gas-phase reaction network for 467 species Garrod et al. (2008), Graedel et al. (1982). We compare our chemical model results with the relative abundances of: CO, CH, OH, HCO+, HCN, HNC, NH3, N2H+ and H2CO molecules. We find significant time dependent variations of the chemical ratios of: X(NH3/H2); X(HCO+/H2) and X(HCO+/NH3). We derive an ammonia age spread for the parts of TMC-1 (Taurus Molecular Cloud-1) that looks more complex than previous estimated showed. Age estimates based on X(NH3/H2); X(HCO+/H2) and X(HCO+/NH3) were compared in 3 selected positions, and were found to be very similar (with ±9% differences).

We present spectral data cubes of the [CI] 809 GHz, 12CO 115 GHz, 13CO 110 GHz and HI 1.4 GHz line emission from a ~1° region along the l = 328° (G328) sightline in the Galactic Plane. The [CI] data comes from the High Elevation Antarctic Terahertz telescope at Ridge A on the summit of the Antarctic plateau, where the extremely low levels of precipitable water vapour open atmospheric windows for THz observations. The CO data comes from the Southern Galactic Plane Survey being conducted with the Mopra telescope. Emission arises principally from gas in three spiral arm crossings along the sight line. The distribution of the emission in the CO and [CI] lines is found to be similar, with the [CI] slightly more extended, and both are enveloped in extensive HI. Spectral line ratios are similar across the entire extent of the Galaxy. However, towards the edges of the molecular clouds the [CI]/13CO and 12CO/13CO line ratios rise by ~ 50%, and the [CI]/Hi ratio falls by ~ 10%. We attribute this to sightlines passing predominantly through the surfaces of photodissociation regions (PDRs), where the carbon is found mainly as C or C+ rather than CO, while the gas is mostly molecular. This is the signature of dark molecular gas.

Our aim is to study the Star Formation Rate (SFR) by galaxy components such as bulges, bars and disks in a representative sample of nearby galaxies. A 2-dimensional (2D) photometric decomposition approach (GASP2D) is used to obtain these components. The availability of IFS data for the CALIFA galaxies makes possible to go one step further as we can apply the previous decompositions over 3D datacubes to disentangle the spatial distribution of the SFR over different components free from the limitations associated to narrow-band imaging.

To study the molecular environment and feedback of Herbig Ae/Be (HAB) stars, We mapped four HAB stars' nearby region with CO (1-0) and its isotopes by the 13.7m millimeter telescope of Purple Mountain Observatory. The results show that new stars are forming in the nearby molecular cores and HAB stars give them an extra pressure. On the other hand, HAB stars are the main heat source of their surrounding gas.

Sensitive, high resolution observations of Galactic neutral hydrogen (Hi) reveal an intricate network of slender linear features, much as sensitive surveys of dust in Galactic molecular clouds reveal ubiquitous filamentary structure. Across the high Galactic latitude sky, diffuse Histructures are aligned with the interstellar magnetic field, as revealed by background starlight polarization (Clark, Peek, & Putman 2014) and by Planck 353 GHz polarized dust emission (Clark et al. 2015). These discoveries were enabled by the Rolling Hough Transform, a recently developed, open source machine vision algorithm.

The statistical description of Giant Molecular Cloud (GMC) properties relies heavily on the performance of automatic identification algorithms, which are often seriously affected by the survey design. The algorithm we designed, SCIMES (Spectral Clustering for Molecular Emission Segmentation), is able to overcome some of these limitations by considering the cloud segmentation problem in the broad framework of the graph theory. The application of the code on the CO(3-2) High Resolution Survey (COHRS) data allowed for a robust decomposition of more than 12,000 objects in the Galactic Plane. Together with the wealth of Galactic Plane surveys of the recent years, this approach will help to open the door to a future, systematic cataloging of all discrete molecular features of our own Galaxy.

The relationship between active galactic nuclei (AGN) and starburst galaxies is poorly understood, partially due to galaxies exhibiting both AGN and starburst activity. To better understand the connection, we analyze a sample of “pure” AGN or starburst at redshift z = 0.1 selected using mean field independent component analysis (MFICA). Simulations of starburst galaxy emission suggests that the locally optimally-emitting cloud (LOC) model can fit observations and improve our ability to distinguish the impact of differences in metallicity, ionization parameter, and ionizing flux. To test for the existence of such clouds in our galaxy sample, we examine the Sloan Digital Sky Survey (SDSS) images of our pure galaxies. At this distance, even large star-forming H II regions (e.g. 30 Doradus) only fill part of an SDSS pixel. However, we compare the morphology of the distant galaxies to more nearby ones (i.e. NGC 4713, NGC 4038/4039) to estimate the number of larger H II regions. While the clumpiness parameter of a galaxy in theory might indicate the existence of these regions, a straightforward calculation of the clumpiness parameter is ineffective for galaxies at z = 0.1. Typically, one subtracts a smoothed version of a galaxy image from the same image. We instead test a different approach to establish a smooth image and thus better identify the clumps. We subtract the smoother infrared z-band from the sharper ultraviolet u-band. We test this procedure using NGC 4713, a nearby starburst galaxy, artificially degraded to match images of our “pure” starburst galaxies.

The Bak Tang Weisenfeld (BTW) sandpile process is a model of a complex dynamical system with a large collection of particles or grains in a node that sheds load to their neighbours when they reach capacity. The cascades move around the system till it reaches stability with a critical point as an attractor. The BTW growth process shows self-organized criticality (SOC) with power- law distribution in cascade sizes having slope -5/3. This self-similarity of structure is synonymous with the fractal structure found in molecular clouds of Kolmogorov dimension 1.67 and by treating cascades as waves, scaling functions are found to be analogous to those observed for velocity structure functions in fluid turbulence. In this paper, we show that this is a naturally occuring universal process giving rise to scale - free structures with size limited only by the number of infalling grains. We also compare the BTW process with other sandpile models such as the Manna and Zhang processes. We find that the BTW sandpile model can be applied to a wide range of objects including molecular clouds, accretion disks and perhaps galaxies.

SPLASH (the Southern Parkes Large-Area Survey in Hydroxyl) is a deep survey of ground-state OH absorption and emission from the Galactic Plane, as well as an unbiased search for OH masers. Key early results include the detection of a rich and complex distribution of diffuse, optically thin OH with strongly non-thermal excitation temperatures, and the detection of numerous new maser sources. The survey aims to use OH as a probe of CO-dark H2 ISM Galactic scales, with future plans including comprehensive comparisons with CO and Hi, as well as non-LTE excitation modelling of the four ground-state lines.

The presence of compact obscured nuclei in luminous infrared galaxies (LIRGs) is very well probed by the detection of highly excited absorption lines of OH and H2O in the far-infrared (far-IR), which require warm and optically thick dust to pump the high-lying rotational levels. We are using a spherically symmetric radiative transfer code to model the H2O lines, OH lines and continuum from these objects. We discuss the results and analysis of Herschel observations of the compact obscured nucleus in the extremely H2O luminous LIRG Zw 049.057. In this galaxy we have found very high H2O abundances in a Compton thick compact core. Abundant 18O bearing species also suggest the presence of a relatively young starburst. We compare this to our observations and modeling of the luminous merger component Arp 299a, which is another source with prominent H2O and OH lines. Our preliminary results, however, suggest that its nuclear activity is in a different evolutionary state compared to Zw 049.057.