Search

We present JWST NIRCam (F356W and F444W filters) and MIRI (F770W) images and NIRSpec- IFU spectroscopy of the young supernova remnant Cassiopeia A (Cas A). We obtained the data as part of a JWST survey of Cas A. The NIRCam and MIRI images map the spatial distributions of synchrotron radiation, Ar-rich ejecta, and CO on both large and small scales, revealing remarkably complex structures. The CO emission is stronger at the outer layers than the Ar ejecta, which indicates the reformation of CO molecules behind the reverse shock. NIRSpec-IFU spectra (3 - 5.5 microns) were obtained toward two representative knots in the NE and S fields. Both regions are dominated by the bright fundamental rovibrational band of CO in the two R and P branches, with strong [Ar VI] and relatively weaker, variable strength ejecta lines of [Si IX], [Ca IV], [Ca V] and [Mg IV]. The NIRSpec-IFU data resolve individual ejecta knots and filaments spatially and in velocity space. The fundamental CO band in the JWST spectra reveals unique shapes of CO, showing a few tens of sinusoidal patterns of rovibrational lines with pseudo-continuum underneath, which is attributed to the high-velocity widths of CO lines. The CO also shows high J lines at different vibrational transitions. Our results with LTE modeling of CO emission indicate a temperature of 1080 K and provide unique insight into the correlations between dust, molecules, and highly ionized ejecta in supernovae, and have strong ramifications for modeling dust formation that is led by CO cooling in the early Universe., Comment: accepted for the ApJ letter (17 pages and 10 figures)

Shockwaves driven by supernovae both destroy dust and reprocess the surviving grains, greatly affecting the resulting dust properties of the interstellar medium (ISM). While these processes have been extensively studied theoretically, observational constraints are limited. We use physically-motivated models of dust emission to fit the infrared (IR) spectral energy distributions of seven Galactic supernova remnants, allowing us to determine the distribution of dust mass between diffuse and dense gas phases, and between large and small grain sizes. We find that the dense ($\sim 10^3 \,{\rm cm}^{-3}$), relatively cool ($\sim 10^3 \, {\rm K}$) gas phase contains $>90\%$ of the dust mass, making the warm dust located in the X-ray emitting plasma ($\sim 1 \,{\rm cm}^{-3}$/$10^6 \, {\rm K}$) a negligible fraction of the total, despite dominating the mid-IR emission. The ratio of small ($\lesssim 10 \, {\rm nm}$) to large ($\gtrsim 0.1 \, {\rm \mu m}$) grains in the cold component is consistent with that in the ISM, and possibly even higher, whereas the hot phase is almost entirely devoid of small grains. This suggests that grain shattering, which processes large grains into smaller ones, is ineffective in the low-density gas, contrary to model predictions. Single-phase models of dust destruction in the ISM, which do not account for the existence of the cold swept-up material containing most of the dust mass, are likely to greatly overestimate the rate of dust destruction by supernovae., Comment: 13 pages, 12 figures. MNRAS accepted

We present a self-consistent cross-calibration of the three main molecular gas mass tracers in galaxies, the $\rm ^{12}CO$(1-0), [CI]($^3P_1$-$^3P_0$) lines, and the submm dust continuum emission, using a sample of 407 galaxies, ranging from local disks to submillimetre-selected galaxies (SMGs) up to $z \approx 6$. A Bayesian method is used to produce galaxy-scale universal calibrations of these molecular gas indicators, that hold over 3-4 orders of magnitude in infrared luminosity, $L_{\rm IR}$. Regarding the dust continuum, we use a mass-weighted dust temperature, $T_{\rm mw}$, determined using new empirical relations between temperature and luminosity. We find the average $L/M_{\rm mol}$ gas mass conversion factors to be $\alpha_{850}= 6.9\times10^{12}\,\rm W\,Hz^{-1}\,M_{\odot}^{-1}$, $\alpha_{\rm CO} = \rm 4\,M_{\odot} (K\,km\,s^{-1}\,pc^2)^{-1}$ and $\alpha_{\rm CI} = \rm 17.0 \,M_{\odot} (K\,km\,s^{-1}\,pc^2)^{-1}$, based on the assumption that the mean dust properties of the sample ($\kappa_H$ = gas-to-dust ratio/dust emissivity) will be similar to those of local metal rich galaxies and the MW. The tracer with the least intrinsic scatter is [CI](1-0), while CO(1-0) has the highest. The conversion factors show a weak but significant correlation with $L_{\rm IR}$. Assuming dust properties typical of metal-rich galaxies, we infer a neutral carbon abundance $X_{\rm CI} = [C^0/\rm mol]=1.6\times 10^{-5}$, similar to that in the MW. We find no evidence for bimodality of $\alpha_{\rm CO}$ between main-sequence (MS) galaxies and those with extreme star-formation intensity, i.e. ULIRGs and SMGs. The means of the three conversion factors are found to be similar between MS galaxies and ULIRGs/SMGs, to within 10-20%. We show that for metal-rich galaxies, near-universal average values for $\alpha_{\rm CO}$, $X_{\rm CI}$ and $\kappa_H$ are adequate for global molecular gas estimates., Comment: 42 pages, accepted for publication in MNRAS. Abstract abridged. Data tables will be available on CDS imminently. Minor changes from proof stage including swapping order of Tables 8 and 9 and small corrections to the bibliography

We have carried out the first spatially-resolved investigation of the multi-phase interstellar medium (ISM) at high redshift, using the z=4.24 strongly-lensed sub-millimetre galaxy H-ATLASJ142413.9+022303 (ID141). We present high-resolution (down to ~350 pc) ALMA observations in dust continuum emission and in the CO(7-6), H_2O (2_{1,1} - 2_{0,2}), CI(1-0) and CI(2-1) lines, the latter two allowing us to spatially resolve the cool phase of the ISM for the first time. Our modelling of the kinematics reveals that the system appears to be dominated by a rotationally-supported gas disk with evidence of a nearby perturber. We find that the CI(1-0) line has a very different distribution to the other lines, showing the existence of a reservoir of cool gas that might have been missed in studies of other galaxies. We have estimated the mass of the ISM using four different tracers, always obtaining an estimate in the range (3.2-3.8) x 10^{11} M_sol, significantly higher than our dynamical mass estimate of (0.8-1.3) x 10^{11} M_sol. We suggest that this conflict and other similar conflicts reported in the literature is because the gas-to-tracer ratios are ~4 times lower than the Galactic values used to calibrate the ISM in high-redshift galaxies. We demonstrate that this could result from a top-heavy initial mass function and strong chemical evolution. Using a variety of quantitative indicators, we show that, extreme though it is at z=4.24, ID141 will likely join the population of quiescent galaxies that appears in the Universe at z~3., Comment: This article has been accepted for publication in MNRAS, published by Oxford University Press on behalf of the Royal Astronomical Society. 24 pages

We present ALMA observations of a small but statistically complete sample of twelve 250 micron selected galaxies at $z=0.35$ designed to measure their dust submillimeter continuum emission as well as their CO(1-0) and atomic carbon [CI](3P1-3P0) spectral lines. This is the first sample of galaxies with global measures of all three $H_2$-mass tracers and which show star formation rates (4-26 Msun yr$^{-1}$) and infra-red luminosities ($1-6\times10^{11}$ Lsun) typical of star forming galaxies in their era. We find a surprising diversity of morphology and kinematic structure; one-third of the sample have evidence for interaction with nearby smaller galaxies, several sources have disjoint dust and gas morphology. Moreover two galaxies have very high $L_{CI}/L_{CO}$ ratios for their global molecular gas reservoirs; if confirmed, such extreme intensity ratios in a sample of dust selected, massive star forming galaxies presents a challenge to our understanding of ISM. Finally, we use the emission of the three molecular gas tracers, to determine the carbon abundance, $X_{ci}$, and CO-$\rm{H_2}$ conversion $\alpha_{co}$ in our sample, using a weak prior that the gas-to-dust ratio is similar to that of the Milky Way for these massive and metal rich galaxies. Using a likelihood method which simultaneously uses all three gas tracer measurements, we find mean values and errors on the mean of $\alpha_{co}=3.0\pm0.5\,\rm{Msun\,(K\,kms^{-1}\,pc^2)^{-1}}$ and $X_{ci}=1.6\pm0.1\times 10^{-5}$ (or $\alpha_{ci}=18.8\,K kms^{-1}\,pc^2 (Msun)^{-1}$) and $\delta_{GDR}=128\pm16$ (or $\alpha_{850}=5.9\times10^{12}\,\rm{W\,Hz^{-1}\, Msun^{-1}}$), where our starting assumption is that these metal rich galaxies have an average gas-to-dust ratio similar to that of the Milky Way centered on $\delta_{GDR}=135$., Comment: 34 pages, published in MNRAS

We build a rigorous statistical framework to provide constraints on the chemical and dust evolution parameters for nearby late-type galaxies with a wide range of gas fractions ($3\%

Dust destruction by supernovae is one of the main processes removing dust from the interstellar medium (ISM). Estimates of the efficiency of this process, both theoretical and observational, typically assume a shock propagating into a homogeneous medium, whereas the ISM possesses significant substructure in reality. We self-consistently model the dust and gas properties of the shocked ISM in three supernova remnants (SNRs), using X-ray and infrared (IR) data combined with corresponding emission models. Collisional heating by gas with properties derived from X-ray observations produces dust temperatures too high to fit the far-IR fluxes from each SNR. An additional colder dust component is required, which has a minimum mass several orders of magnitude larger than that of the warm dust heated by the X-ray emitting gas. Dust-to-gas mass ratios indicate that the majority of the dust in the X-ray emitting material has been destroyed, while the fraction of surviving dust in the cold component is plausibly close to unity. As the cold component makes up virtually all the total dust mass, destruction timescales based on homogeneous models, which cannot account for multiple phases of shocked gas and dust, may be significantly overestimating actual dust destruction efficiencies, and subsequently underestimating grain lifetimes., Comment: 12 pages, 9 figures. MNRAS accepted 31/10/2020

We investigate the evolution of the gas mass fraction for galaxies in the COSMOS field using submillimetre emission from dust at 850$\mu$m. We use stacking methodologies on the 850$\mu$m S2COSMOS map to derive the gas mass fraction of galaxies out to high redshifts, 0 <= $z$ <= 5, for galaxies with stellar masses of $10^{9.5} < M_* (\rm M_{\odot}) < 10^{11.75}$. In comparison to previous literature studies we extend to higher redshifts, include more normal star-forming galaxies (on the main sequence), and also investigate the evolution of the gas mass fraction split by star-forming and passive galaxy populations. We find our stacking results broadly agree with scaling relations in the literature. We find tentative evidence for a peak in the gas mass fraction of galaxies at around $z$ ~ 2.5-3, just before the peak of the star formation history of the Universe. We find that passive galaxies are particularly devoid of gas, compared to the star-forming population. We find that even at high redshifts, high stellar mass galaxies still contain significant amounts of gas., Comment: 17 pages (+ 9 pages of appendices), 8 figures (+ 7 figures in appendices), accepted for publication in MNRAS

The Herschel-ATLAS unbiased survey of cold dust in the local Universe is dominated by a surprising population of very blue (FUV-K < 3.5), dust-rich galaxies with high gas fractions (f_HI = M_HI/(M*+M_HI)>0.5)). Dubbed `Blue and Dusty Gas Rich Sources' (BADGRS) they have cold diffuse dust temperatures, and the highest dust-to-stellar mass ratios of any galaxies in the local Universe. Here, we explore the molecular ISM in a representative sample of BADGRS, using very deep CO(J_up=1,2,3) observations across the central and outer disk regions. We find very low CO brightnesses (Tp=15-30 mK), despite the bright far-infrared emission and metallicities in the range 0.5

We have modelled the near-infrared to radio images of the Crab Nebula with a Bayesian SED model to simultaneously fit its synchrotron, interstellar and supernova dust emission. We infer an interstellar dust extinction map with an average $A_{\text{V}}$=1.08$\pm$0.38 mag, consistent with a small contribution (<22%) to the Crab's overall infrared emission. The Crab's supernova dust mass is estimated to be between 0.032 and 0.049 M$_{\odot}$ (for amorphous carbon grains) with an average dust temperature $T_{\text{dust}}$=41$\pm$3K, corresponding to a dust condensation efficiency of 8-12%. This revised dust mass is up to an order of magnitude lower than some previous estimates, which can be attributed to our different interstellar dust corrections, lower SPIRE flux densities, and higher dust temperature than were used in previous studies. The dust within the Crab is predominantly found in dense filaments south of the pulsar, with an average V-band dust extinction of $A_{\text{V}}$=0.20-0.39 mag, consistent with recent optical dust extinction studies. The modelled synchrotron power-law spectrum is consistent with a radio spectral index $\alpha_{\text{radio}}$=0.297$\pm$0.009 and an infrared spectral index $\alpha_{\text{IR}}$=0.429$\pm$0.021. We have identified a millimetre excess emission in the Crab's central regions, and argue that it most likely results from two distinct populations of synchrotron emitting particles. We conclude that the Crab's efficient dust condensation (8-12%) provides further evidence for a scenario where supernovae can provide substantial contributions to the interstellar dust budgets in galaxies., Comment: 33 pages, 17 figures, Manuscript accepted for publication in MNRAS. Accepted on 31/05/2019. Deposited on 31/05/2019

The {\it Herschel} Astrophysical Terahertz Large Area Survey (H-ATLAS) is a survey of 660 deg$^2$ with the PACS and SPIRE cameras in five photometric bands: 100, 160, 250, 350 and 500\mic. This is the second of three papers describing the data release for the large fields at the south and north Galactic poles (NGP and SGP). In this paper we describe the catalogues of far-infrared and submillimetre sources for the NGP and SGP, which cover 177 deg$^2$ and 303 deg$^2$, respectively. The catalogues contain 153,367 sources for the NGP field and 193,527 sources for the SGP field detected at more than 4$\sigma$ significance in any of the 250, 350 or 500\mic\ bands. The source detection is based on the 250\mic\ map, and we present photometry in all five bands for each source, including aperture photometry for sources known to be extended. The rms positional accuracy for the faintest sources is about 2.4 arc seconds in both right ascension and declination. We present a statistical analysis of the catalogues and discuss the practical issues -- completeness, reliability, flux boosting, accuracy of positions, accuracy of flux measurements -- necessary to use the catalogues for astronomical projects.

We present the dust mass function (DMF) of 15,750 galaxies with redshift $z< 0.1$, drawn from the overlapping area of the GAMA and {\it H-}ATLAS surveys. The DMF is derived using the density corrected $V_{\rm max}$ method, where we estimate $V_{\rm max}$ using: (i) the normal photometric selection limit ($pV_{\rm max}$) and (ii) a bivariate brightness distribution (BBD) technique, which accounts for two selection effects. We fit the data with a Schechter function, and find $M^{*}=(4.65\pm0.18)\times 10^{7}\,h^2_{70}\, M_{\odot}$, $\alpha=(1.22\pm 0.01)$, $\phi^{*}=(6.26\pm 0.28)\times 10^{-3}\,h^3_{70}\,\rm Mpc^{-3}\,dex^{-1}$. The resulting dust mass density parameter integrated down to $10^4\,M_{\odot}$ is $\Omega_{\rm d}=(1.11 \pm0.02)\times 10^{-6}$ which implies the mass fraction of baryons in dust is $f_{m_b}=(2.40\pm0.04)\times 10^{-5}$; cosmic variance adds an extra 7-17\,per\,cent uncertainty to the quoted statistical errors. Our measurements have fewer galaxies with high dust mass than predicted by semi-analytic models. This is because the models include too much dust in high stellar mass galaxies. Conversely, our measurements find more galaxies with high dust mass than predicted by hydrodynamical cosmological simulations. This is likely to be from the long timescales for grain growth assumed in the models. We calculate DMFs split by galaxy type and find dust mass densities of $\Omega_{\rm d}=(0.88\pm0.03)\times 10^{-6}$ and $\Omega_{\rm d}=(0.060\pm0.005)\times 10^{-6}$ for late-types and early-types respectively. Comparing to the equivalent galaxy stellar mass functions (GSMF) we find that the DMF for late-types is well matched by the GMSF scaled by $(8.07\pm0.35) \times 10^{-4}$., Comment: 25 Pages, 18 Figures. Submitted December 2017

The process of planet formation offers a rich source of dust production via grain growth in protostellar discs, and via grinding of larger bodies in debris disc systems. Chemical evolution models, designed to follow the build up of metals and dust in galaxies, do not currently account for planet formation. We consider the possibility that the apparent under-prediction of dust mass in high redshift galaxies by chemical evolution models could be in part, due to these models neglecting this process, specifically due to their assumption that a large fraction of the dust mass is removed from the interstellar medium during star formation (so-called astration). By adding a planet formation phase into galaxy chemical evolution, we demonstrate that the dust budget crisis can be partially ameliorated by a factor of 1.3-1.5 only if a) circumstellar discs prevent a large fraction of the dust mass entering the star during its birth, and b) that dust mass is preferentially liberated via jets, winds and outflows rather than accreted into planetary-mass bodies., Comment: 9 pages, 11 figures, accepted for publication in MNRAS

We present infrared (IR) and submillimeter observations of the Crab-like supernova remnant (SNR) G54.1+0.3 including 350 micron (SHARC-II), 870 micron (LABOCA), 70, 100, 160, 250, 350, 500 micron (Herschel) and 3-40 micron (Spitzer). We detect dust features at 9, 11 and 21 micron and a long wavelength continuum dust component. The 21 micron dust coincides with [Ar II] ejecta emission, and the feature is remarkably similar to that in Cas A. The IRAC 8 micron image including Ar ejecta is distributed in a shell-like morphology which is coincident with dust features, suggesting that dust has formed in the ejecta. We create a cold dust map that shows excess emission in the northwestern shell. We fit the spectral energy distribution of the SNR using the continuous distributions of ellipsoidal (CDE) grain model of pre-solar grain SiO2 that reproduces the 21 and 9 micron dust features and discuss grains of SiC and PAH that may be responsible for the 10-13 micron dust features. To reproduce the long-wavelength continuum, we explore models consisting of different grains including Mg2SiO4, MgSiO3, Al2O3, FeS, carbon, and Fe3O4. We tested a model with a temperature-dependent silicate absorption coefficient. We detect cold dust (27-44 K) in the remnant, making this the fourth such SNR with freshly-formed dust. The total dust mass in the SNR ranges from 0.08-0.9 Msun depending on the grain composition, which is comparable to predicted masses from theoretical models. Our estimated dust masses are consistent with the idea that SNe are a significant source of dust in the early Universe., Comment: MNRAS: accepted on June 28, 2018 and published on July 4, 2018

Most massive stars end their lives in core-collapse supernova explosions and enrich the interstellar medium with explosively nucleosynthesized elements. Following core collapse, the explosion is subject to instabilities as the shock propagates outwards through the progenitor star. Observations of the composition and structure of the innermost regions of a core-collapse supernova provide a direct probe of the instabilities and nucleosynthetic products. SN 1987A in the Large Magellanic Cloud (LMC) is one of very few supernovae for which the inner ejecta can be spatially resolved but are not yet strongly affected by interaction with the surroundings. Our observations of SN 1987A with the Atacama Large Millimeter/submillimeter Array (ALMA) are of the highest resolution to date and reveal the detailed morphology of cold molecular gas in the innermost regions of the remnant. The 3D distributions of carbon and silicon monoxide (CO and SiO) emission differ, but both have a central deficit, or torus-like distribution, possibly a result of radioactive heating during the first weeks ("nickel heating"). The size scales of the clumpy distribution are compared quantitatively to models, demonstrating how progenitor and explosion physics can be constrained., Comment: ApJL accepted, 9 pages, 5 figures

We combine samples of nearby galaxies with Herschel photometry selected on their dust, metal, HI, and stellar mass content, and compare these to chemical evolution models in order to discriminate between different dust sources. In a companion paper, we used a HI-selected sample of nearby galaxies to reveal a sub-sample of very gas rich (gas fraction > 80 per cent) sources with dust masses significantly below predictions from simple chemical evolution models, and well below $M_d/M_*$ and $M_d/M_{gas}$ scaling relations seen in dust and stellar-selected samples of local galaxies. We use a chemical evolution model to explain these dust-poor, but gas-rich, sources as well as the observed star formation rates (SFRs) and dust-to-gas ratios. We find that (i) a delayed star formation history is required to model the observed SFRs; (ii) inflows and outflows are required to model the observed metallicities at low gas fractions; (iii) a reduced contribution of dust from supernovae (SNe) is needed to explain the dust-poor sources with high gas fractions. These dust-poor, low stellar mass galaxies require a typical core-collapse SN to produce 0.01 - 0.16 $M_{\odot}$ of dust. To match the observed dust masses at lower gas fractions, significant grain growth is required to counteract the reduced contribution from dust in SNe and dust destruction from SN shocks. These findings are statistically robust, though due to intrinsic scatter it is not always possible to find one single model that successfully describes all the data. We also show that the dust-to-metals ratio decreases towards lower metallicity., Comment: 15 pages (+10 pages appendix), 8 figures, Accepted for publication in MNRAS

Theoretical models predict that core-collapse supernovae (CCSNe) can be efficient dust producers (0.1-1.0 Msun), potentially accounting for most of the dust production in the early Universe. Observational evidence for this dust production efficiency is however currently limited to only a few CCSN remnants (e.g., SN1987A, Crab Nebula). In this paper, we revisit the dust mass produced in Cassiopeia A (Cas A), a ~330-year old O-rich Galactic supernova remnant (SNR) embedded in a dense interstellar foreground and background. We present the first spatially resolved analysis of Cas A based on Spitzer and Herschel infrared and submillimetre data at a common resolution of ~0.6 arcmin for this 5 arcmin diameter remnant following a careful removal of contaminating line emission and synchrotron radiation. We fit the dust continuum from 17 to 500 micron with a four-component interstellar medium (ISM) and supernova (SN) dust model. We find a concentration of cold dust in the unshocked ejecta of Cas A and derive a mass of 0.3-0.5 Msun of silicate grains freshly produced in the SNR, with a lower limit of >=0.1-0.2 Msun. For a mixture of 50% of silicate-type grains and 50% of carbonaceous grains, we derive a total SN dust mass between 0.4 Msun and 0.6 Msun. These dust mass estimates are higher than from most previous studies of Cas A and support the scenario of supernova dominated dust production at high redshifts. We furthermore derive an interstellar extinction map for the field around Cas A which towards Cas A gives average values of A_V=6-8 mag, up to a maximum of A_V=15 mag., Comment: 37 pages, 24 figures, Manuscript published in MNRAS, including minor corrections. Accepted on 01/11/2016. Deposited on 08/01/2017

We present a study of the dust, stars and atomic gas (HI) in an HI-selected sample of local galaxies (z<0.035) in the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS) fields. This HI-selected sample reveals a population of very high gas fraction (>80 per cent), low stellar mass sources that appear to be in the earliest stages of their evolution. We compare this sample with dust and stellar mass selected samples to study the dust and gas scaling relations over a wide range of gas fraction (proxy for evolutionary state of a galaxy). The most robust scaling relations for gas and dust are those linked to NUV-r (SSFR) and gas fraction, these do not depend on sample selection or environment. At the highest gas fractions, our additional sample shows the dust content is well below expectations from extrapolating scaling relations for more evolved sources, and dust is not a good tracer of the gas content. The specific dust mass for local galaxies peaks at a gas fraction of ~75 per cent. The atomic gas depletion time is also longer for high gas fraction galaxies, opposite to the trend found for molecular gas depletion timescale. We link this trend to the changing efficiency of conversion of HI to H2 as galaxies increase in stellar mass surface density as they evolve. Finally, we show that galaxies start out barely obscured and increase in obscuration as they evolve, yet there is no clear and simple link between obscuration and global galaxy properties., Comment: 16 pages (+11 pages appendix), 12 figures, Published in 2017 in MNRAS, 464, 4680; This version 2 has corrected a small error in the table heading of Table 1, but is otherwise unchanged

In this paper we consider the implications of the distributions of dust and metals in the disc of M31. We derive mean radial dust distributions using a dust map created from Herschel images of M31 sampling the entire far-infrared (FIR) peak. Modified blackbodies are fit to approximately 4000 pixels with a varying, as well as a fixed, dust emissivity index (beta). An overall metal distribution is also derived using data collected from the literature. We use a simple analytical model of the evolution of the dust in a galaxy with dust contributed by stellar sources and interstellar grain growth, and fit this model to the radial dust-to-metals distribution across the galaxy. Our analysis shows that the dust-to-gas gradient in M31 is steeper than the metallicity gradient, suggesting interstellar dust growth is (or has been) important in M31. We argue that M31 helps build a case for cosmic dust in galaxies being the result of substantial interstellar grain growth, while the net dust production from stars may be limited. We note, however, that the efficiency of dust production in stars, e.g., in supernovae (SNe) ejecta and/or stellar atmospheres, and grain destruction in the interstellar medium (ISM) may be degenerate in our simple model. We can conclude that interstellar grain growth by accretion is likely at least as important as stellar dust production channels in building the cosmic dust component in M31., Comment: 12 pages, 7 figures. Published in MNRAS 444, 797. This version is updated to match the published version

We present a comparison of the physical properties of a rest-frame $250\mu$m selected sample of massive, dusty galaxies from $01$ SMGs have an average SFR of $390^{+80}_{-70}\,$M$_\odot$yr$^{-1}$ which is 120 times that of the low-redshift sample matched in stellar mass to the SMGs (SFR$=3.3\pm{0.2}$ M$_\odot$yr$^{-1}$). The SMGs harbour a substantial mass of dust ($1.2^{+0.3}_{-0.2}\times{10}^9\,$M$_\odot$), compared to $(1.6\pm0.1)\times{10}^8\,$M$_\odot$ for low-redshift dusty galaxies. At low redshifts the dust luminosity is dominated by the diffuse ISM, whereas a large fraction of the dust luminosity in SMGs originates from star-forming regions. At the same dust mass SMGs are offset towards a higher SFR compared to the low-redshift H-ATLAS galaxies. This is not only due to the higher gas fraction in SMGs but also because they are undergoing a more efficient mode of star formation, which is consistent with their bursty star-formation histories. The offset in SFR between SMGs and low-redshift galaxies is similar to that found in CO studies, suggesting that dust mass is as good a tracer of molecular gas as CO., Comment: 17 pages, 8 pages in Appendix, 12 figures, 2 tables. Accepted for publication in MNRAS. Minor typos corrected to match published version

We apply a chemical evolution model to investigate the sources and evolution of dust in a sample of 26 high-redshift ($z>1$) submillimetre galaxies (SMGs) from the literature, with complete photometry from ultraviolet to the submillimetre. We show that dust produced only by low-intermediate mass stars falls a factor 240 short of the observed dust masses of SMGs, the well-known `dust-budget crisis'. Adding an extra source of dust from supernovae can account for the dust mass in 19 per cent of the SMG sample. Even after accounting for dust produced by supernovae the remaining deficit in the dust mass budget provides support for higher supernova yields, substantial grain growth in the interstellar medium or a top-heavy IMF. Including efficient destruction of dust by supernova shocks increases the tension between our model and observed SMG dust masses. The models which best reproduce the physical properties of SMGs have a rapid build-up of dust from both stellar and interstellar sources and minimal dust destruction. Alternatively, invoking a top-heavy IMF or significant changes in the dust grain properties can solve the dust budget crisis only if dust is produced by both low mass stars and supernovae and is not efficiently destroyed by supernova shocks., Comment: 21 pages including 1 page appendix, 5 figures, 6 tables. Accepted for publication in MNRAS

Whether supernovae are major sources of dust in galaxies is a long-standing debate. We present infrared and submillimeter photometry and spectroscopy from the Herschel Space Observatory of the Crab Nebula between 51 and 670 micron as part of the Mass Loss from Evolved StarS program. We compare the emission detected with Herschel with multiwavelength data including millimeter, radio, mid-infrared and archive optical images. We carefully remove the synchrotron component using the Herschel and Planck fluxes measured in the same epoch. The contribution from line emission is removed using Herschel spectroscopy combined with Infrared Space Observatory archive data. Several forbidden lines of carbon, oxygen and nitrogen are detected where multiple velocity components are resolved, deduced to be from the nitrogen-depleted, carbon-rich ejecta. No spectral lines are detected in the SPIRE wavebands; in the PACS bands, the line contribution is 5% and 10% at 70 and 100 micron and negligible at 160 micron. After subtracting the synchrotron and line emission, the remaining far-infrared continuum can be fit with two dust components. Assuming standard interstellar silicates, the mass of the cooler component is 0.24(+0.32)(-0.08) Msolar for T = 28.1(+5.5)(-3.2)K. Amorphous carbon grains require 0.11 +/- 0.01 Msolar of dust with T = 33.8(+2.3)(-1.8) K. A single temperature modified-blackbody with 0.14Msolar and 0.08Msolar for silicate and carbon dust respectively, provides an adequate fit to the far- infrared region of the spectral energy distribution but is a poor fit at 24-500 micron. The Crab Nebula has condensed most of the relevant refractory elements into dust, suggesting the formation of dust in core-collapse supernova ejecta is efficient., Comment: 12 pages, 6 figures, ApJ in press, final version after proofs corrected

We present an analysis of the dust and gas in Andromeda, using Herschel images sampling the entire far-infrared peak. We fit a modified-blackbody model to ~4000 quasi-independent pixels with spatial resolution of ~140pc and find that a variable dust-emissivity index (beta) is required to fit the data. We find no significant long-wavelength excess above this model suggesting there is no cold dust component. We show that the gas-to-dust ratio varies radially, increasing from ~20 in the center to ~70 in the star-forming ring at 10kpc, consistent with the metallicity gradient. In the 10kpc ring the average beta is ~1.9, in good agreement with values determined for the Milky Way (MW). However, in contrast to the MW, we find significant radial variations in beta, which increases from 1.9 at 10kpc to ~2.5 at a radius of 3.1kpc and then decreases to 1.7 in the center. The dust temperature is fairly constant in the 10kpc ring (ranging from 17-20K), but increases strongly in the bulge to ~30K. Within 3.1kpc we find the dust temperature is highly correlated with the 3.6 micron flux, suggesting the general stellar population in the bulge is the dominant source of dust heating there. At larger radii, there is a weak correlation between the star formation rate and dust temperature. We find no evidence for 'dark gas' in M31 in contrast to recent results for the MW. Finally, we obtained an estimate of the CO X-factor by minimising the dispersion in the gas-to-dust ratio, obtaining a value of (1.9+/-0.4)x10^20 cm^-2 [K kms^-1]^-1., Comment: 19 pages, 18 figures. Submitted to ApJ April 2012; Accepted July 2012

We present photometry of the nearby galaxy NGC 5128 (Centaurus A) observed with the PACS and SPIRE instruments on board the Herschel Space Observatory, at 70, 160, 250, 350 and 500 {\mu}m, as well as new CO J = 3-2 observations taken with the HARP-B instrument on the JCMT. Using a single component modified blackbody, we model the dust spectral energy distribution within the disk of the galaxy using all five Herschel wavebands, and find dust temperatures of ~30 K towards the centre of the disk and a smoothly decreasing trend to ~20 K with increasing radius. We find a total dust mass of (1.59 \pm 0.05) \times 10^7 M\odot, and a total gas mass of (2.7 \pm 0.2) \times 10^9 M\odot. The average gas-to-dust mass ratio is 103 \pm 8 but we find an interesting increase in this ratio to approximately 275 toward the centre of Cen A. We discuss several possible physical processes that may be causing this effect, including dust sputtering, jet entrainment and systematic variables such as the XCO factor. Dust sputtering by X-rays originating in the AGN or the removal of dust by the jets are our most favoured explanations., Comment: Accepted for publication in MNRAS; 11 pages, 8 figures, 1 table

UV and optical surveys are essential to gain insight into the processes driving galaxy formation and evolution. The rest-frame UV emission is key to measure the cosmic SFR. However, UV light is strongly reddened by dust. In starburst galaxies, the UV colour and the attenuation are linked, allowing to correct for dust extinction. Unfortunately, evidence has been accumulating that the relation between UV colour and attenuation is different for normal star-forming galaxies when compared to starburst galaxies. It is still not understood why star-forming galaxies deviate from the UV colour-attenuation relation of starburst galaxies. Previous work and models hint that the role of the shape of the attenuation curve and the age of stellar populations have an important role. In this paper we aim at understanding the fundamental reasons to explain this deviation. We have used the CIGALE SED fitting code to model the far UV to the far IR emission of a set of 7 reasonably face-on spiral galaxies from the HRS. We have explored the influence of a wide range of physical parameters to quantify their influence and impact on the accurate determination of the attenuation from the UV colour, and why normal galaxies do not follow the same relation as starburst galaxies. We have found that the deviation can be best explained by intrinsic UV colour differences between different regions in galaxies. Variations in the shape of the attenuation curve can also play a secondary role. Standard age estimators of the stellar populations prove to be poor predictors of the intrinsic UV colour. These results are also retrieved on a sample of 58 galaxies when considering their integrated fluxes. When correcting the emission of normal star-forming galaxies for the attenuation, it is crucial to take into account possible variations in the intrinsic UV colour as well as variations of the shape of the attenuation curve., Comment: Accepted for publication in A&A, 18 pages, 14 figures. The paper with high resolution figures can be downloaded at http://www.oamp.fr/people/mboquien/HRS/boquien_IRX_beta.pdf

The origin of interstellar dust in galaxies is poorly understood, particularly the relative contributions from supernovae and the cool stellar winds of low-intermediate mass stars. Here, we present Herschel PACS and SPIRE photometry at 70-500um of the historical young supernova remnants: Kepler and Tycho; both thought to be the remnants of Type Ia explosion events. We detect a warm dust component in Kepler's remnant with T = 82K and mass 0.0031Msun; this is spatially coincident with thermal X-ray emission optical knots and filaments, consistent with the warm dust originating in the circumstellar material swept up by the primary blast wave of the remnant. Similarly for Tycho's remnant, we detect warm dust at 90K with mass 0.0086Msun. Comparing the spatial distribution of the warm dust with X-rays from the ejecta and swept-up medium, and Ha emission arising from the post-shock edge, we show that the warm dust is swept up interstellar material. We find no evidence of a cool (25-50 K) component of dust with mass >0.07Msun as observed in core-collapse remnants of massive stars. Neither the warm or cold dust components detected here are spatially coincident with supernova ejecta material. We compare the lack of observed supernova dust with a theoretical model of dust formation in Type Ia remnants which predicts dust masses of 0.088(0.017)Msun for ejecta expanding into surrounding densities of 1(5)cm-3. The model predicts that silicon- and carbon-rich dust grains will encounter the interior edge of the observed dust emission at 400 years confirming that the majority of the warm dust originates from swept up circumstellar or interstellar grains (for Kepler and Tycho respectively). The lack of cold dust grains in the ejecta suggests that Type Ia remnants do not produce substantial quantities of iron-rich dust grains and has important consequences for the 'missing' iron mass observed in ejecta., Comment: 17 pages, 14 figures, accepted for publication in MNRAS, final version including corrected typos and references

We report on the detection of anhydrous hydrochloric acid (hydrogen chlorine, HCl) in the carbon-rich star IRC+10216 using the spectroscopic facilities onboard the Herschel satellite. Lines from J=1-0 up to J=7-6 have been detected. From the observed intensities, we conclude that HCl is produced in the innermost layers of the circumstellar envelope with an abundance relative to H2 of 5x10^-8 and extends until the molecules reach its photodissociation zone. Upper limits to the column densities of AlH, MgH, CaH, CuH, KH, NaH, FeH, and other diatomic hydrides have also been obtained., Comment: Accepted for publication in Astronomy and Astrophysics (Herschel special issue)

Using the 3.5-m Herschel Space Observatory, imaging photometry of Cas A has been obtained in six bands between 70 um and 500 um with the PACS and SPIRE instruments, with angular resolutions ranging from 6 to 37". In the outer regions of the remnant the 70-um PACS image resembles the 24-um image Spitzer image, with the emission attributed to the same warm dust component, located in the reverse shock region. At longer wavelengths, the three SPIRE bands are increasingly dominated by emission from cold interstellar dust knots and filaments, particularly across the central, western and southern parts of the remnant. Nonthermal emission from the northern part of the remnant becomes prominent at 500 um. We have estimated and subtracted the contributions from the nonthermal, warm dust and cold interstellar dust components. We confirm and resolve for the first time a cool (~35 K) dust component, emitting at 70-160 um, that is located interior to the reverse shock region, with an estimated mass of 0.075 Msun., Comment: Accepted for A&A Herschel special issue. 1 table, 3 figures

We present Herschel SPIRE and PACS photometeric observations of the low metallicity (Z ~ 0.35 solar) nearby dwarf galaxy, NGC 1705, in six wavelength bands as part of the Dwarf Galaxy Survey guaranteed time Herschel Key Program. We confirm the presence of two dominant circumnuclear IR-bright regions surrounding the central super star cluster that had been previously noted at mid-IR wavelengths and in the sub-mm by LABOCA. On constructing a global spectral energy distribution using the SPIRE and PACS photometry, in conjunction with archival IR measurements, we note the presence of an excess at sub-mm wavelengths. This excess suggests the presence of a significant cold dust component within NGC 1705 and was modeled as an additional cold component in the SED. Although alternative explanations for the sub-mm excess beyond 350 microns, such as changes to the dust emissivity cannot be ruled out, the most likely explanation for the observed submillimetre excess is that of an additional cold dust component., Comment: 5 pages, 2 figures, accepted for publication in A&A (Herschel special issue)

With appropriate spatial resolution, images of spiral galaxies in thermal infrared (~10 micron and beyond) often reveal a bright central component, distinct from the stellar bulge, superimposed on a disk with prominent spiral arms. ISO and Spitzer studies have shown that much of the scatter in the mid-infrared colors of spiral galaxies is related to changes in the relative importance of these two components, rather than to other modifications, such as the morphological type or star formation rate, that affect the properties of the galaxy as a whole. With the Herschel imaging capability from 70 to 500 micron, we revisit this two-component approach at longer wavelengths, to see if it still provides a working description of the brightness distribution of galaxies, and to determine its implications on the interpretation of global far-infrared properties of galaxies., Comment: 5 pages, 2 figures, accepted for the A&A Herschel Special Issue

Previous submillimetre (submm) observations detected 0.7 solar masses of cool dust emission around the Luminous Blue Variable (LBV) star Eta Carinae. These observations were hindered by the low declination of Eta Carinae and contamination from free-free emission orginating from the stellar wind. Here, we present deep submm observations with LABOCA at 870um, taken shortly after a maximum in the 5.5-yr radio cycle. We find a significant difference in the submm flux measured here compared with the previous measurement: the first indication of variability at submm wavelengths. A comparison of the submm structures with ionised emission features suggests the 870um is dominated by emission from the ionised wind and not thermal emission from dust. We estimate 0.4 +/- 0.1 solar masses of dust surrounding Eta Carinae. The spatial distribution of the submm emission limits the mass loss to within the last thousand years, and is associated with mass ejected during the great eruptions and the pre-outburst LBV wind phase; we estimate that Eta Carinae has ejected > 40 solar masses of gas within this timescale., Comment: 5 pages, 3 figures, accepted by MNRAS Letters

Whether or not supernovae contribute significantly to the overall dust budget is a controversial subject. Submillimetre (submm) observations, sensitive to cold dust, have shown an excess at 450 and 850 microns in young remnants Cassiopeia A (Cas A) and Kepler. Some of the submm emission from Cas A has been shown to be contaminated by unrelated material along the line of sight. In this paper we explore the emission from material towards Kepler using submm continuum imaging and spectroscopic observations of atomic and molecular gas, via HI, 12CO (J=2-1) and 13CO (J=2-1). We detect weak CO emission (peak TA* = 0.2-1K, 1-2km/s fwhm) from diffuse, optically thin gas at the locations of some of the submm clumps. The contribution to the submm emission from foreground molecular and atomic clouds is negligible. The revised dust mass for Kepler's remnant is 0.1--1.2 solar masses, about half of the quoted values in the original study by Morgan et al. (2003), but still sufficient to explain the origin of dust at high redshifts., Comment: 12 pages, 9 figures, accepted to MNRAS