Conveners
Poster Presentations: Poster Presentations
- Christa Gall (Dark Cosmology Centre)
Poster Presentations: Poster Presentations
- Christa Gall (Dark Cosmology Centre)
Poster Presentations
- Christa Gall (Dark Cosmology Centre)
Poster Presentations
- Francesco Valentino (Niels Bohr Institute - University of Copenhagen)
Poster Presentations: Poster Presentations
- Francesco Valentino (Niels Bohr Institute - University of Copenhagen)
Poster Presentations: Poster Presentations
- Francesco Valentino (Niels Bohr Institute - University of Copenhagen)
Description
Quick presentation of posters
Asymptotic giant branch (AGB) stars are luminous, cool giants with non-spherical morphology and substantial mass loss. Dust formed in the stellar atmospheres plays a key role for the mass-loss mechanism: radial pulsations of the surface layers of the stars levitate material to distances where dust can form, which then is accelerated outward by radiation pressure. AGB stars are significant dust...
The dusty obscuring structure around the active galactic nuclei (AGN), commonly referred to as the ‘torus’, provides the angle-dependent obscuration as postulated in the Unification Scheme of AGN. This dust rich environment supplies the central engine with material for accretion and is known to thermally absorb optical light from the accretion disc and re-emit it in the infrared (IR). The time...
Massive stars signpost places of their birth in molecular clouds with expanding HII regions and photodissociation regions (PDRs). The HII regions and PDRs have very specific observational manifestation on Spitzer images. Namely, the ring-like structures which are seen at 8 micron surround the inner regions which are bright at 24 micron. The ring-like structures are also seen on Herschel...
We have used the VISIR spectrograph at the Very Large Telescope to target 21 of the most luminous and heavily-obscured oxygen-rich evolved AGB stars in the galaxy. Low resolution N-band (8 - 13 um) spectroscopy was used to target the 10 μm silicate feature. The sample, with a median luminosity of ~10,000 solar luminosities and a median mass loss rate of ~10E-4 solar masses per year, has shown...
Polycyclic Aromatic Hydrocarbon (PAH) molecules are ubiquitous carbonaceous molecules, responsible for the Aromatic Infrared Bands (AIB) dominating the IR spectrum of diverse astronomical environments, from planetary and reflection nebulae, to transitional disks to entire galaxies (Tielens, 2013). PAHs make up the low-mass end of the grain size distribution (Weingartner & Draine 2001) and,...
We examine polycyclic aromatic hydrocarbon (PAH), dust and atomic/molecular emission toward the Galactic bulge using $\textit{Spitzer}$ Space Telescope observations of four fields: C32, C35, OGLE and NGC 6522. These fields are approximately centered on (l, b) = (0.0°, 1.0°), (0.0°, -1.0°), (0.4°, -2.1°) and (1.0°, -3.8°), respectively. Far-infrared photometric observations complement the...
The properties of a particular dust mix are encoded in the extinction curve, which is notoriously hard to measure. In all but a few external galaxies, it is not possible to resolve individual stars and match them to local, unreddened stars of the same spectral type. Most measurements for external galaxies are thus global attenuation curves, which hold a convolution with the line-of-sight...
Due to observational limitations, the size and structure of the obscuring circumnuclear dust in active galactic nuclei (AGN) is not well understood. Using reverberation mapping techniques the size of this hot dust emission can be determined by analyzing the temporal variations of the infrared (IR) emission from the dust in response to variations in the accretion disk continuum luminosity. Over...
Dust properties in the Small Magellanic Cloud (SMC) provide insight into the interstellar environment of one of the closest analogs to early-Universe and low-metallicity galaxies. We examine the spatial variations in dust extinction curve properties and the three-dimensional structure in the Southwest Bar of the SMC using resolved stellar populations observed with the \textit{Hubble Space...
We are measuring and analysing the FIR- and THz- Spectra of pyrolysed micro-crystalline cellulose as an analogue of carbonaceous interstellar dust. We are using cellulose-powder with crystal sizes of about 20\,$\mu$m and are heating it up to 1000$^{\circ}$C. First results of the mass normalised extinction are presented and compared to J\"ager et al. (1998). The temperature dependent...
During the late stages of their evolution, asymptotic giant branch (AGB) stars experience significant mass loss processes, which result in extended circumstellar envelopes (CSEs). These environments are efficient factories of molecules and dust grains. The main paradigm for the dust formation process involves a first step in which condensation nuclei of nanometer size are formed from some...
The ESO Diffuse Interstellar Band Large Exploration Survey (EDIBLES) is Large Programme that is collecting high-signal-to-noise (S/N) spectra of a large sample of O and B-type stars covering a large spectral range using the UVES spectrograph mounted on the Very Large Telescope (VLT). The goal of the programme is to extract a unique sample of high-quality interstellar spectra from these data...
The dust-to-metals ratio provides insights into the life cycle of dust. We measure the dust-to-metals ratio in M101, a nearby galaxy with a radial metallicity gradient spanning $\sim 1~\mbox{dex}$. We fit the dust spectral energy distribution (SED) from $100$ to $500~\mu m$ with five variants of the modified blackbody (MBB) dust emission model (free $\beta$, fixed $\beta$, broken emissivity,...
With the AKARI all-sky maps, we conduct a systematic study of dust and star formation for the 260 local early-type galaxies (ETGs) from the ATLAS3D survey, for which cold (HI and CO) and hot (X-ray) gas measurements are available. We detected far-infrared dust emission in 30% of the ETGs, where the dust emission is not correlated with the stellar emission, indicating that dust in those...
We present a new model of interstellar dust composed of silicates, graphitic carbonaceous grains, and polycyclic aromatic hydrocarbons that reproduces the wavelength dependence of dust extinction (total and polarized) and emission (total and polarized) in the diffuse interstellar medium from UV to microwave wavelengths. In this talk, I will focus on the use of new observational data,...
Debris disks are often modelled assuming compact dust grains, but more and more evidence for the presence of porous grains is found. We quantify the systematic errors introduced when modelling debris disks -- composed of porous dust grains -- assuming the presence of spherical, compact particles (Brunngräber et al. 2017).
We use the effective medium theory to calculate the optical properties...
Debris disks contain very fine dust but the lifetime of these dust grains is much shorter than the stellar age. It implies that these dust grains are not primordial and must be replenished continuously through mutual collisions of dust-producing planetesimals.
We investigated the impact of mutual collisions on the observational appearance of eccentric debris disks. For this purpose we...
Dust enrichment is one of the most important aspects in galaxy evolution.
The evolution of dust is tightly coupled with the nonlinear evolution of
the ISM including star formation and stellar feedback,
which drive the chemical enrichment in a galaxy.
Hydrodynamical simulation provides a powerful approach
to studies of such nonlinear processes.
In this work, we perform a smoothed particle...
The amount of dust in the interstellar medium (ISM) is directly linked to physical quantities that trace the evolution of galaxies. The emission from dust has been proposed as a probe of the amount of star formation within a galaxy and the physical properties of the dust are related to those of the ISM where it is located. Therefore, understanding better how the dust physical properties change...
The dynamics of dust grains vary depending on the forces that act on them at different environments in the multi-phase interstellar medium (ISM). Grains interact with the gas through collisions, gravitational attraction and long-range coulomb forces, and also experience varying coupling strengths to magnetic field lines depending on their charge. The charge distribution of dust grains in the...
Infrared observations of AGN reveal the emission from a dusty circumnuclear "torus" that is heated up by radiation from the central accreting black hole (BH). The strong 9.7 and 18 micron silicate features observed in the AGN spectra both in emission and absorption, further indicate the presence of such dusty environment. The origin of this dust is presently unclear. It could be pre-existing...
The HFI instrument onboard the Planck satellite has allowed us to characterize the statistical and spectral properties of dust polarized emission over the whole sky in the submillimeter wavelength range.
Dust polarization is not only useful to trace the magnetic field orientation or to test alignment theories. It is also a way to characterize the spectral properties of the dust population that...
The shape of the dust attenuation law is not expected to be uniform between galaxies, nor within a galaxy. The DustKING project sets to study these variations in nearby galaxies of the KINGFISH sample. To this aim, we used the CIGALE SED fitting code to fit models with varying dust extinction properties to a set of multi-wavelength data. Particularly important for our goal are UV images taken...
The DustPedia project is capitalising on the legacy of the Herschel Space Observatory, using cutting-edge modelling techniques to study dust in the 875 DustPedia galaxies - representing the vast majority of extended galaxies within 3000 km/s (~40 Mpc) that were observed by Herschel. This work requires a database of multiwavelength imagery and photometry that greatly exceeds the scope (in terms...
The dust properties of nearby galaxies are often inferred by modeling their infrared (IR) spectral energy distributions (SEDs), using dust grain models. These are created with a simplified radiation model, with assumptions on the intensity and hardness of the radiation field.
Using the Draine & Li (2007; DL07) dust model, we create a set of synthetic dust emission SEDs with a 3D radiative...
Cosmic dust provides a significant contribution to the absorption of electromagnetic radiation at all galactic scales. Hydrogen ionizing radiation (hν ≥ 13.6 eV) emitted from star forming regions has to survive the large columns of gas and dust present in the galactic ISM of normal high-z galaxies before contributing to the IGM reionization process. Nevertheless, dust absorption is rarely...
Our knowledge of the shape of the ultraviolet (UV) extinction curve informs our understanding of topics from the composition of dust grains in the ISM to how we interpret the shape of galaxy SEDs. I will discuss two complementary approaches to measuring the extinction curve.
First, we use resolved stellar populations in the Large Magellanic Cloud to determine the extinction curve shape along...
We provide new temperature-dependent optical constants of silicate glasses, silicate minerals, and crystalline and amorphous water ice, in the sub-millimeter spectral range, for silicate glasses up to a wavelength of 4 mm. We compare these optical constants to literature data, such as the ``astronomical silicate'' and commonly used extrapolations of the water-ice opacity. We discuss physical...
An analysis of interstellar absorption features in UV stellar spectra in the HST and FUSE archives reveals column densities of O I, Ge II, Kr I, Mn II, Mg II, H I and H$_2$ in many different directions. Expanding on an earlier study by Jenkins (2009), this effort probes the partial correlations of the element abundances of O, Ge, and Kr relative to hydrogen for three fundamental parameters: ...
Dust grains play an important role in star formation also in the early Universe. The stellar initial mass function is considered to transfer from top-heavy to the normal Salpeter one in the course of metal/dust enrichment of interstellar medium because thermal emission cooling by dust grains induce the fragmentation of their parent gas clouds. However, dust properties such as size distribution...
Hot exozodiacal dust emission was detected around several main sequence stars at distances of less than 1 au using NIR and MIR interferometry. Studies of exozodis offer a way to better understand the inner regions of extrasolar planetary systems, and the possible presence of small grains in exozodiacal clouds is a potential problem for the detection of terrestrial planets in the habitable zone...
The development of extremely sensitive mm/submm telescopes (e.g. ALMA, NOEMA) opened a new window to the far infrared (FIR) continuum emitted by dust, which enables us to investigate the obscured star-formation history of the Universe. Using these new facilities, recent studies of the dust properties of early galaxies revealed unexpected results, as high redshift galaxies show much lower FIR...
We model the thermal emission from a distribution of dust grains heated by particle collisions and the ambient supernova remnant radiation field, under conditions representative of the knots observed in Cassiopeia A (Cas A). In order to reproduce the observed Cas A dust spectral energy distribution reported by de Looze et al. (2017), we require dust emission from both the pre- and post-shock...
Sub-millimetre observations of galaxies at redshift z>6 have revealed dust masses of up to 10^8 solar masses (e.g. Bertoldi and Cox, 2002). As such systems are thought too young for significant dust enrichment by asymptotic giant branch (AGB) stars to have occurred, core-collapse supernovae (CCSNe) have been suggested as possible alternative dust producers (Nozawa et al. 2003, Dwek et al....
We have updated the SED fitting code "CIGALE" so that it includes dust properties based on the "THEMIS" model (Jones et al. 2017, A&A, 602, 46). We use this tool to fit the SED of 875 nearby galaxies with available photometry from the FUV to the sub-millimeter wavelengths. For this sample of galaxies (the "DustPedia" galaxies – Davies et al. 2017, PASP, 129, 4102) we are able to derive global...
We study the variability of the dust characteristics from cloud-to-cloud in the diffuse ISM (arXiv:1711.08672). We took low-resolution spectro-polarimetric data obtained in the context of the Large Interstellar Polarisation Survey (LIPS, arXiv:1710.02439) towards 59 sight-lines in the southern hemisphere, and we fitted these data using a dust model composed of silicate and carbon. Particles...
Photodissociation regions (PDRs) are parts of the ISM consisting of predominantly neutral gas, located at the interface between HII regions and molecular clouds. The physical conditions within these regions show variations on very short length scales, and therefore PDRs form ideal laboratories for investigating the properties and evolution of dust grains. Recently, observations of the IC63 PDR...
IR emission features at 3.3, 6.2, 7.7, 8.6 and 11.3 $ \mu $m are usually attributed to IR fluorescence from FUV pumped polycyclic aromatic hydrocarbons (PAHs). These features thus trace the FUV stellar flux and are a measure of star formation in the Universe. Here, we present results from a detailed study on the mid-IR emission features of HII regions in M83 and M33, with the aim to...
The content of the interstellar medium (ISM) is very important for the evolution of the Galaxy and for star formation processes. Today it is known that the structure of the ISM mainly consists of gas, dust and molecules. However, the composition of dust in the ISM is not yet fully understood. Insights can be gained from the X-ray band. High-resolution X-ray spectroscopy is a powerful method to...
Astronomical measurements of S abundances in the diffuse interstellar medium (ISM) indicate ionized S is a dominant species with little (< 5%) S residing in grains (e.g. Jenkins 2009). This is an enigmatic result, given that abundant Fe-sulfide grains are observed in dust around pre- and post-main sequence stars (Keller et al. 2002; Hony et al. 2002) and are also observed as major components...
As a part of interstellar dust, polycyclic aromatic hydrocarbons (PAHs) are processed by the interaction with vacuum ultraviolet (VUV) photons that are emitted by young stars [1]. After absorption of a VUV photon, an isolated PAH can undergo different relaxation processes: ionization, dissociation and radiative cooling, including infrared (IR) fluorescence which results in the aromatic...
The formation of dust in the envelopes of evolved stars is still poorly understood. It is generally admitted that the C/O ratio in the envelope is a key parameter determining the type of dust that is formed and thus leading to either carbon-rich nanograins, possibly including polycyclic aromatics hydrocarbons (PAHs), or oxygen-rich nanograins mainly silicates.
In order to get further insights...
Here we present the prospects of observing dust features of important constitutents of the ISM (C, Al, S, Ca) using future X-ray facilities (Arcus, XARM and Athena).
Present instruments already probed the diffuse interstellar medium (e.g. Costantini et al. 2012) and the moderately dense environments (Zeegers et al. 2017).
However, carbon, one of the main constituents of the ISM, is currently...
Dust grains are subjected to various destruction mechanisms in the interstellar medium (ISM). Together these mechanisms operate at a rate faster than the injection of grains condensed in stellar outflows and supernova ejecta. Nevertheless, comparatively long-lived dust populations are observed in the ISM. The local re-formation or growth of grains has been proposed as a process that...
The final stages of the evolution of intermediate mass stars ($M\sim 1-8 M_\odot$) are characterised by the ejection of their envelope as they evolve off the Asymptotic Giant Branch (AGB), producing a spectacular planetary nebula (PN). In particular, this phase is characterised by the development of strong asymmetries in the circumstellar medium, with a large fraction of PNe and pre-PNe...
Observational evidence has long supported that most of the interstellar silicates in galaxies are amorphous. While crystalline silicates may form around evolved stars at temperatures sufficiently high to allow for annealing, it is thought that the harsh interstellar environment quickly amorphitizes any crystalline silicates, most likely through bombardment by the heavy ions in cosmic rays...
The two Magellanic clouds and our Galaxy are known to have been tidally interacting each other in the past $\sim$ billion years. It is indicated by the elongated distributions of interstellar medium (ISM), known as the Magellanic stream and the Magellanic bridge. Numerical simulations of the dynamical interactions of these galaxies successfully reproduced these features. This dynamical...
Asymptotic Giant Branch (AGB) stars dominate the total dust injection into the interstellar medium (ISM) of galaxies. Studies providing total dust injection rates in the Milky Way (Jura & Kleinmann 1989) and nearby galaxies (Riebel et al. 2012; Srinivasan et al, 2016) show the importance of accurately estimating this contribution. In this work we revisit the total dust mass-loss rate from AGB...
The dust porosity is a key quantity that characterizes how dust particles grow to form planetesimals in protoplanetary disks. We study how the dust porosity affects scattered light images of protoplanetary disks in near-infrared wavelengths. It is known from near-infrared observations that some protoplanetary disks are faint and show red color in the scattered light. Large fluffy dust...
Large aromatic molecules are ubiquitous in astrophysical environments such as star forming regions, galaxies and planetary nebulae in which they emit the Aromatic Infrared Bands (AIBs). These molecules include polycyclic aromatic hydrocarbons (PAHs) but also fullerenes, C60 being the only molecule of this class identified so far. Emission in the AIBs is triggered by the absorption of a UV...
The absorption fine structures, imprinted by the interaction between X-rays and solid particles, can reveal the composition, the size, and the structure of cosmic dust (Costantini et al. 2012). The iron K-edge is particularly important because it is well visible in the X-ray band providing a large extinction especially for lines of sight with N$_{\rm{H}} > 10^{23} \rm{cm}^{-2}$ (A$_{\rm{V}}>...
The Nearby Evolved Stars Survey (NESS) is a multi-telescope project targeting a volume-limited ($d < 2$ kpc) sample of $\sim$400 evolved stars, including 104 oxygen-rich stars (including $\sim$20 red supergiants), 8 S-type stars, and 19 carbon-rich AGB stars, as well as many post-AGB stars and planetary nebulae. NESS includes a 500-h ongoing JCMT survey of dust continuum as well as CO (2-1)...
During the last few decades many debris disks have been found and resolved around A to K-type stars. However, only a handful of debris disks have been discovered around M-stars, and the reasons for their paucity remain unclear.
Here we check whether the sensitivity and wavelength coverage of present-day telescopes are simply unfavorable for detection of these disks or if they are truly rare....
The mid-infrared (MIR) spectrum of many astronomical sources show prominent emission features at 3.3, 6.2, 7.7, 8.6, 11.2, and 12.7 $\mu$m attributed to the IR fluorescence of polycyclic aromatic hydrocarbons (PAHs). We use spatial maps of the 3.3 and 11.2 $\mu$m PAH emission features to measure the distribution of PAH size within two reflection nebulae with strong MIR emission present, namely...
In the interstellar medium (ISM), the carbon (nano-)grains are a major component of interstellar dust. This solid phase is more vulnerable to processing/destruction than their silicate counterparts. It exhibits a complex, size-dependent evolution due to photon interactions, which provides a modeling challenge. How these micro-physical processes work under the extreme conditions found in disks...
One of the main tools to study dust grain properties is to measure the extinction curves in sightlines toward stars in the Local Group or extragalactic lighthouses such as quasars, gamma-ray bursts and supernovae. Typically, the extinction curves seen in the extragalactic, interstellar medium can be well-described by extinction curves similar to those observed in the Small and Large Magellanic...
The Galactic dust emission is a main obstacle to detect the cosmic microwave background (CMB) B-mode polarization signals originated from primordial gravitational waves. Accurate removal of the Galactic dust emission from the data is crucial for the success. Although a single power law frequency dependence has been usually assumed both for the dust emissivity and polarization SEDs, they might...
A broad emission dust feature peaking around 30 microns is seen in the spectra of some carbon-rich AGB stars, post AGBs, and PNe. Since the discovery by Forrest et al. (1981) this dust feature has been detected in plenty of carbon-rich objects. Magnesium sulphide (MgS) is now the most favoured candidate to be the carrier of this spectral feature, but its identification remains a matter of some...
High resolution interferometric observations of infrared emission from dust in the immediate environment of AGNs reveal that the warm dust is extended in the polar directions. This suggests a scenario where warm dust is raised above the plane of the AGN through a radiation-pressure driven wind. We have produced a 3D radiation hydrodynamic model including self-gravity effects, and radiation...
The source of the large masses of dust observed in some very early Universe galaxies at redshifts z $>$ 6 has been much debated. Core-collapse supernovae (CCSNe) have been predicted to be efficient producers of dust but the majority have only had small masses of warm dust ($<$ 10$^{-3}$ M${_\odot}$) detected in their ejecta during their early phases (t $<$ 3 years), based on fits to their...
The mid-IR spectra of photodissociation regions (PDRs) are dominated by the well-known emission features at 3.3, 6.2, 7.7, 11.3, and 12.7 micron, generally attributed to polycyclic aromatic hydrocarbon molecules (PAHs). PAHs drive much of the physics and the chemistry in these PDRs, e.g. by heating the gas and as a catalyst in the formation of molecular hydrogen on their surfaces. Thus, PAHs...
The mid-IR spectra of almost all objects are dominated by strong emission bands at 3.3, 6.2, 7.7, 8.6, and 11.3 micron due to Polycyclic Aromatic Hydrocarbon molecules (PAHs). It is now well established that these mid-IR bands show clear variations in shape and peak position from one point source to another, as well as varying spatially within extended sources. The spectral diversity of the...
SN 1987A, being relatively young as well as the brightest supernova observed in over 400 years, is a unique and exciting laboratory for studying supernova dust production. Located around 50kpc away in the Large Magellanic Cloud, SN 1987A is too far away for single-dish telescopes to resolve the structure of the sub-mm emission on the scale of the ejecta, where the dust is produced. Recent...
We compare vertical profiles of the extraplanar H𝛼 emission to those of the UV emission for 38 nearby edge-on late-type galaxies. It is found that detection of the “diffuse” extraplanar dust (eDust), traced by the vertically extended, scattered UV starlight, always coincides with the presence of the extraplanar H𝛼 emission. A strong correlation between the scale heights of the extraplanar H𝛼...
From infrared (IR) observations it is known that magnesium silicates are the major dust component in protoplanetary disks. From such observations one can discern the likely size, composition and crystallinity of such dust thus allowing one to infer the likely associated properties of the disk. Of special interest are the disks surrounding Herbig Ae/Be (HAeBe) stars corresponding to the stellar...
X-ray imaging and spectroscopy can provide a powerful tool for measuring the large end of the dust grain size distribution — important for interpretting infrared extinction as well as understanding grain growth in the diffuse interstellar medium (ISM). In addition, X-ray photoelectric absorption edges observed in high resolution spectra of Galactic X-ray binaries directly reveal the mineral...
Within the framework of the DustPedia project we study the effect of cosmic dust on a vast sample of nearby galaxies. Dust radiative transfer (RT) simulations provide us with the unique opportunity to study the heating mechanisms of dust by the stellar radiation field. From 2D FITS images we were able to derive the 3D geometry distributions of stars, a technique, first introduced by De Looze...
Silicate dust is pervasive throughout the cosmos and has been observed in interstellar space, around evolved oxygen-rich stars, protoplanetary disks, and in our Solar System. The chemical and physical properties of this dust have traditionally been inferred through remote astronomical observations. Spectral observations of circumstellar dust indicate mainly amorphous, Fe-bearing grains having...
The interstellar dust extinction in the near- and mid-infrared (IR)
wavelength range (1-40 microns) is characterized by decreasing
continuum extinction and four main absorption features that are
diagnostic of dust grain compositions. The absorption features at 10
and 18 micron are due to silicate material, at 3.4 micron due to
hydrogenated carbon material, and at 3.0 micron due to water...
Photodissociation regions (PDRs) are predominantly neutral regions of the ISM in which
the heating and chemistry are mainly regulated by far ultraviolet photons emitted from
one or more nearby young stars. They are extended regions at the interface between
the ionizing sources and molecular clouds, and contain dense structures and clumps of
dust and gas immersed in a more diffuse medium. Dust...
During the formation of the Solar System, Jupiter and Saturn played an important role in modulating and controlling the dust dynamics through the formation of gaps in the protosolar accretion disk that acted as dust traps. This is reflected in the distribution of chondrules and calcium-aluminum inclusions (CAIs). CAIs are almost exclusively present in chondrites arriving from the outer Solar...
Disks and envelopes around protostars play a fundamental role in the process of planet formation, since they contain the ingredients that will form planets. However, it is not yet clear at which stage of the star and planet formation process dust grains start to efficiently coagulate and evolve from small solid particles to macroscopic dimensions.
We studied the Class I protostar, Per-emb-50,...
The experimental setup was developed with the goal to characterize the optical properties of astrophysically relevant solids (ice mixtures, silicates, and carbonaceous materials). For the experiments, we use a combination of spectral techniques to obtain information regarding their chemical, physical, and optical properties. When analysed, together with astronomical observations and...
The desorption of molecular ices from grain surfaces is important in a number of astrophysical environments including dense molecular clouds, circumstellar regions, cometary nuclei, and surfaces and atmospheres of planets. It has been shown that for multicomponent ices within water ice matrices, the desorption of all species in the ice is controlled by the behaviour of water. A study of the...
We present a fundamental measure of the dust content of nearby galaxies - the Dust Mass Function (DMF) for the largest sample of galaxies to date. Our DMF is drawn from a stellar mass selected sample of galaxies comprised of the overlap between two large area surveys - the Galaxy And Mass Assembly (GAMA), and the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS). The overlap between...
In the field of astrochemistry and surface science a primary objective is to identify and characterize effective catalysts which have a plausible existence in the interstellar medium (ISM). Molecular hydrogen ($H_2$) is the most abundant molecule in the ISM with well-established and efficient catalytic formation routes in many regions of interstellar space. However, in certain regions of the...
Carbonaceous surfaces are known to act as catalysts for the formation of molecular hydrogen in the interstellar medium [1,2]. Molecular hydrogen is the most abundant molecule in the universe and it controls the chemistry of the interstellar medium. Hence, the formation of molecular hydrogen is the first step in the evolution of the chemical complexity of the interstellar medium.
Observations...
We present new CO(1-0) line observations of 34 infrared-selected PAH emitters at intermediate redshift (0.01≤ z ≤ 0.3) to investigate the connection among the PAH emission, the total gas content, and the star formation rate in normal and starbursting galaxies. Combined with observations from the literature at low and high redshift, our analysis reveals a universal, tight, and linear PAH-CO...
The spatial variations of dust properties within a galaxy and their
correlation with local environment provide critical insights into the life cycle of dust. Low metallicity galaxies, in particular, let one study the dust life cycle in environments relevant for galaxies earlier in the history of the Universe.
In this work, we present maps of the dust properties in the Small and Large...
Dust can be found everywhere in the universe from stars in the latest stages of evolution (post-AGB stars), to the interstellar medium (ISM) and protoplanetary disks around young stars (e.g. T Tauri and Herbig Ae/Be stars). Dust can provide a wealth of information about the medium it is embedded in, since processing will affect its composition, structure and size in a characteristic and...
The formation of molecular hydrogen, $\mathrm{H_2}$, in the ISM is thought to primarily occur on dust grain surfaces. This process has been investigated extensively through a variety of experimental and theoretical approaches for several different model grain surfaces. More recently it has been suggested that PAHs, representing the molecular limit of the carbonaceous grain population, can act...
Massive stars disrupt their natal molecular cloud material by dissociating molecules, ionizing atoms and molecules, and heating the gas and dust. These processes drive the evolution of interstellar matter in our Galaxy and throughout the Universe from the era of vigorous star formation at redshifts of 1-3, to the present day. Much of this interaction occurs in Photo-Dissociation Regions...
