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.
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 mu m 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 mu m and negligible at 160 mu m. 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 super(+0.32) sub(-0.08) M sub(middot in circle) for T = 28.1 super(+5.5) sub(-3.2) K. Amorphous carbon grains require 0.11 + or - 0.01 M sub(middot in circle) of dust with T = 33.8 super(+2.3) sub(-1.8) K. A single temperature modified blackbody with 0.14 M sub(middot in circle) and 0.08 M sub(middot in circle) 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 mu m. 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.
We present the properties of the first 250 μm blind sample of nearby galaxies (15 < D < 46 Mpc) containing 42 objects from the Herschel Astrophysical Terahertz Large Area Survey. Herschel's ...sensitivity probes the faint end of the dust luminosity function for the first time, spanning a range of stellar mass (7.4 < M
⋆ < 11.3 log10 M⊙), star formation activity (−11.8 < SSFR < −8.9 log10 yr−1), gas fraction (3–96 per cent), and colour (0.6 < FUV–K
S < 7.0 mag). The median cold dust temperature is 14.6 K, colder than in the Herschel Reference Survey (18.5 K) and Planck Early Release Compact Source Catalogue (17.7 K). The mean dust-to-stellar mass ratio in our sample is higher than these surveys by factors of 3.7 and 1.8, with a dust mass volume density of (3.7 ± 0.7) × 105 M⊙ Mpc−3. Counter-intuitively, we find that the more dust rich a galaxy, the lower its UV attenuation. Over half of our dust-selected sample are very blue in FUV–K
S colour, with irregular and/or highly flocculent morphology; these galaxies account for only 6 per cent of the sample's stellar mass but contain over 35 per cent of the dust mass. They are the most actively star-forming galaxies in the sample, with the highest gas fractions and lowest UV attenuation. They also appear to be in an early stage of converting their gas into stars, providing valuable insights into the chemical evolution of young galaxies.
ABSTRACT
We present a self-consistent cross-calibration of the three main molecular gas mass tracers in galaxies, namely the 12CO(1–0), C i(3P1–3P0) lines, and the submm dust continuum emission, ...using a sample of 407 galaxies, ranging from local discs to submillimetre-selected galaxies (SMGs) up to z ≈ 6. A Bayesian statistical 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, LIR. Regarding the dust continuum, we use a mass-weighted dust temperature, Tmw, determined using new empirical relations between temperature and luminosity. We find the average L/Mmol gas mass conversion factors (including He) to be ${\alpha _{850}}=6.9\times 10^{12}\, \rm W\, Hz^{-1}\, M_{\odot }^{-1}$, αCO = 4.0 M⊙ (κ km s−1 pc2)−1, and $\alpha _{\rm C\, I}$ = 17.0 M⊙ (κ km s−1 pc2)−1, based on the assumption that the mean dust properties of the sample (κH = gas-to-dust ratio/dust emissivity) will be similar to those of local metal rich galaxies and the Milky Way. The tracer with the least intrinsic scatter is C i(1–0), while CO(1–0) has the highest. The conversion factors show a weak but significant correlation with LIR which is not apparent when Tmw is held constant. Assuming dust properties typical of metal-rich galaxies, we infer a neutral carbon abundance ${X_{\rm C\, I}}=\rm C^0/\rm{H_2}=1.6\times 10^{-5}$, similar to that in the Milky Way. We find no evidence for bi-modality of αCO between main-sequence (MS) galaxies and those with extreme star-formation intensity, i.e. ultraluminous infrared galaxies (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 per cent. The overarching conclusion of our work is that, for metal-rich galaxies, near-universal average values for αCO, $X_{\rm C\, I}$, and κH are adequate for global molecular gas estimates within the expected uncertainties. The 1σ scatter in our optimized values for αCO, $X_{\rm C\, I}$, and κH are 0.14, 0.11, and 0.15 dex, respectively.
Anti-tumour necrosis factor (TNF) monoclonal antibodies or soluble TNF receptors have become an invaluable treatment against chronic inflammatory diseases, such as rheumatoid arthritis, inflammatory ...bowel disease and psoriasis. Individuals who are treated with TNF antagonists are at an increased risk of reactivating latent infections, especially tuberculosis (TB). Following TNF antagonist therapy, the relative risk for TB is increased up to 25 times, depending on the clinical setting and the TNF antagonist used. Interferon-γ release assays or, as an alternative in individuals without a history of bacille Calmette-Guérin vaccination, tuberculin skin testing is recommended to screen all adult candidates for TNF antagonist treatment for the presence of latent infection with Mycobacterium tuberculosis. Moreover, paediatric practice suggests concomitant use of both the tuberculin skin test and an interferon-γ release assay, as there are insufficient data in children to recommend one test over the other. Consequently, targeted preventive chemotherapy is highly recommended for all individuals with persistent M. tuberculosis-specific immune responses undergoing TNF antagonist therapy as it significantly reduces the risk of progression to TB. This TBNET consensus statement summarises current knowledge and expert opinions and provides evidence-based recommendations to reduce the TB risk among candidates for TNF antagonist therapy.
We present Herschel observations of 62 early-type galaxies (ETGs), including 39 galaxies morphologically classified as S0+S0a and 23 galaxies classified as ellipticals using SPIRE at 250, 350, and ...500 mu m as part of the volume-limited Herschel Reference Survey (HRS). We detect dust emission in 24% of the ellipticals and 62% of the S0s. The mean temperature of the dust is left angle bracketT sub(d)right angle bracket = 23.9 + or - 0.8 K, warmer than that found for late-type galaxies in the Virgo Cluster. The mean dust mass for the entire detected early-type sample is logM sub(d) = 6.1 + or - 0.1 M with a mean dust-to-stellar-mass ratio of log(M sub(d)/Ml ow *) = -4.3 + or - 0.1. Including the non-detections, these parameters are logM sub(d) = 5.6 + or - 0.1 and log(M sub(d)/Ml ow *) = -5.1 + or - 0.1, respectively. The average dust-to-stellar-mass ratio for the early-type sample is fifty times lower, with larger dispersion, than the spiral galaxies observed as part of the HRS, and there is an order-of-magnitude decline in M sub(d)/Mlow * between the S0s and ellipticals. We use UV and optical photometry to show that virtually all the galaxies lie close to the red sequence yet the large number of detections of cool dust, the gas-to-dust ratios, and the ratios of far-infrared to radio emission all suggest that many ETGs contain a cool interstellar medium similar to that in late-type galaxies. We show that the sizes of the dust sources in S0s are much smaller than those in early-type spirals and the decrease in the dust-to-stellar-mass ratio from early-type spirals to S0s cannot simply be explained by an increase in the bulge-to-disk ratio. These results suggest that the disks in S0s contain much less dust (and presumably gas) than the disks of early-type spirals and this cannot be explained simply by current environmental effects, such as ram-pressure stripping. The wide range in the dust-to-stellar-mass ratio for ETGs and the lack of a correlation between dust mass and optical luminosity suggest that much of the dust in the ETGs detected by Herschel has been acquired as the result of interactions, although we show these are unlikely to have had a major effect on the stellar masses of the ETGs. The Herschel observations tentatively suggest that in the most massive systems, the mass of interstellar medium is unconnected to the evolution of the stellar populations in these galaxies.
Theoretical models predict that core-collapse supernovae (CCSNe) can be efficient dust producers (0.1-1.0 M...), 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. SN 1987A, Crab nebula). In this paper, we revisit the dust mass produced in Cassiopeia A (Cas A), a ~330-yr 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 ...m with a four-component interstellar medium 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 M... of silicate grains freshly produced in the SNR, with a lower limit of greater than or equal to 0.1-0.2 M... For a mixture of 50 per cent of silicate-type grains and 50 per cent of carbonaceous grains, we derive a total SN dust mass between 0.4 and 0.6 M... These dust mass estimates are higher than from most previous studies of Cas A and support the scenario of SN-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 sub( V) = 6-8 mag, up to a maximum of A sub( V) = 15 mag. (ProQuest: ... denotes formulae/symbols omitted.)
Abstract
We combine samples of nearby galaxies with Herschel photometry selected on their dust, metal, H i 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 an H i-selected sample of nearby galaxies to reveal a subsample 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⊙ 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-metal ratio decreases towards lower metallicity.
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. Recently, large ...masses of newly formed dust have been discovered in the ejecta of core-collapse supernovae. Here, we present Herschel Photodetector Array Camera and Spectrometer (PACS) and Spectral and Photometric Imaging Receiver (SPIRE) photometry at 70-500
m 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
and mass
; this is spatially coincident with thermal X-ray emission and 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
with mass
. Comparing the spatial distribution of the warm dust with X-rays from the ejecta and swept-up medium, and Hα 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 ≥0.07 M⊙ 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 88(17) × 10−3 M⊙ for ejecta expanding into ambient surrounding densities of 1(5) cm−3. The model predicts that silicon- and carbon-rich dust grains will encounter, at most, 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. Finally, although, we cannot completely rule out a small mass of freshly formed supernova dust, the Herschel observations confirm that significantly less dust forms in the ejecta of Type Ia supernovae than in the remnants of core-collapse explosions.
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 peak. Modified blackbodies are fit to approximately 4000 pixels with a varying, as well as a fixed, dust emissivity index (β). 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 ejecta and/or stellar atmospheres, and grain destruction in the interstellar medium 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.
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![Dust, CO, and [C i ]: cros...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/0035-8711_1365-8711_1365-2966/small "Dust, CO, and [C i ]: cross-calibration of molecular gas mass tracers in metal-rich galaxies across cosmic time")
