We investigate the dust energy balance for the edge-on galaxy IC 2531, one of the seven galaxies in the HEROES sample. We perform a state-of-the-art radiative transfer modelling based, for the first ...time, on a set of optical and near-infrared galaxy images. We show that by taking into account near-infrared imaging in the modelling significantly improves the constraints on the retrieved parameters of the dust content. We confirm the result from previous studies that including a young stellar population in the modelling is important to explain the observed stellar energy distribution. However, the discrepancy between the observed and modelled thermal emission at far-infrared wavelengths, the so-called dust energy balance problem, is still present: the model underestimates the observed fluxes by a factor of about two. We compare two different dust models, and find that dust parameters, and thus the spectral energy distribution in the infrared domain, are sensitive to the adopted dust model. In general, the THEMIS model reproduces the observed emission in the infrared wavelength domain better than the popular BARE-GR-S model. Our study of IC 2531 is a pilot case for detailed and uniform radiative transfer modelling of the entire HEROES sample, which will shed more light on the strength and origins of the dust energy balance problem.
ABSTRACT
The dust mass absorption coefficient, κd is the conversion function used to infer physical dust masses from observations of dust emission. However, it is notoriously poorly constrained, and ...it is highly uncertain how it varies, either between or within galaxies. Here we present the results of a proof-of-concept study, using the DustPedia data for two nearby face-on spiral galaxies M 74 (NGC 628) and M 83 (NGC 5236), to create the first ever maps of κd in galaxies. We determine κd using an empirical method that exploits the fact that the dust-to-metals ratio of the interstellar medium is constrained by direct measurements of the depletion of gas-phase metals. We apply this method pixel-by-pixel within M 74 and M 83, to create maps of κd. We also demonstrate a novel method of producing metallicity maps for galaxies with irregularly sampled measurements, using the machine learning technique of Gaussian process regression. We find strong evidence for significant variation in κd. We find values of κd at 500 $\mu$m spanning the range 0.11–0.25 ${\rm m^{2}\, kg^{-1}}$ in M 74, and 0.15–0.80 ${\rm m^{2}\, kg^{-1}}$ in M 83. Surprisingly, we find that κd shows a distinct inverse correlation with the local density of the interstellar medium. This inverse correlation is the opposite of what is predicted by standard dust models. However, we find this relationship to be robust against a large range of changes to our method – only the adoption of unphysical or highly unusual assumptions would be able to suppress it.
Context.
In recent years, significant growth in the amount of data available to astronomers has opened up the possibility for extensive multi-wavelength approaches. In the field of galaxy evolution, ...such approaches have uncovered fundamental correlations, linking the dust component of a galaxy to its star formation rate (SFR). Despite these achievements, the relation between the SFR and the dust is still challenging, with uncertainties related to the physical mechanisms linking the two.
Aims.
In this paper, we re-examine these correlations, paying specific attention to the intrinsic properties of the dust. Our goal is to investigate the origin of the observed scatter in low-redshift galaxies, and the ability of the
James Webb
Space Telescope (JWST) to explore such relations in the early Universe.
Methods.
We defined a sample of about 800 normal star-forming galaxies with photometries in the range of 0.15 <
λ
< 500 μm and analysed them with different spectral energy distribution (SED) fitting methods. With the SEDs extracted, we investigated the detection rate at different redshifts with the MId-Infrared instruments (MIRI) on board the JWST.
Results.
Dust luminosity (
L
d
) and SFR show a strong correlation, but for SFR < 2
M
⊙
yr
−1
, the correlation scatter increases dramatically. We show that selection based on the fraction of ultraviolet (UV) emission absorbed by dust, that is, the UV extinction, greatly reduces the data dispersion. Dust masses (
M
d
) and SFR show a weaker correlation, with a larger scatter due to the interstellar radiation field produced by stars during late evolutionary stages, which shifts the positions of the galaxies in the dust mass–SFR plane. At
z
= 2, more than 60% of the galaxies in the sample are detected with
F
770,
F
1000,
F
1280,
F
1500, and
F
1800. At higher redshifts, the detection decreases, and only 45% of
z
= 8 galaxies are detected with two filters. Reproducing the expected sensitivity of the Cosmic Evolution Early Release Science Survey and classifying galaxies according to their SFR and stellar mass (
M
*
), we investigated the MIRI detection rate as a function of the physical properties of the galaxies. Fifty percent of the objects with SFR ∼ 1
M
⊙
yr
−1
at
z
= 6 are detected with
F
770, which decreases to 20% at
z
= 8. For such galaxies, only 5% of the subsample will be detected at 5
σ
with
F
770 and
F
1000 at
z
= 8, and only 10% with
F
770,
F
1000, and
F
1280 at
z
= 6. For galaxies with higher SFR, detection with these three filters will be possible up to
z
= 6 in ∼60% of the subsample.
Conclusions.
The link between dust and star formation is complex, and many aspects remain to be fully understood. The scatter between SFR and dust mass, and SFR and luminosity, decreases significantly when the analysis includes dust properties. In this context, the JWST will revolutionise the field, allowing investigation of the dust–star interplay well within the epoch of reionisation.
This paper addresses a long-standing problem in the field of accounting: mapping company-specific ledger accounts to a standardized chart of accounts. We propose a novel solution, TopoLedgerBERT, a ...unique sentence embedding method devised specifically for ledger account mapping. This model integrates hierarchical information from the charts of accounts into the sentence embedding process, aiming to accurately capture both the semantic similarity and the hierarchical structure of the ledger accounts. In addition, we introduce a data augmentation strategy that enriches the training data and, as a result, increases the performance of our proposed model. Compared to benchmark methods, TopoLedgerBERT demonstrates superior performance in terms of accuracy and mean reciprocal rank.
Context. Dust reprocesses about half of the stellar radiation in galaxies. The thermal re-emission by dust of absorbed energy is considered to be driven merely by young stars so is often applied to ...tracing the star formation rate in galaxies. Recent studies have argued that the old stellar population might be responsible for a non-negligible fraction of the radiative dust heating.Aims. In this work, we aim to analyze the contribution of young (≲100 Myr) and old (~10 Gyr) stellar populations to radiative dust heating processes in the nearby grand-design spiral galaxy M 51 using radiative transfer modeling. High-resolution 3D radiative transfer (RT) models are required to describe the complex morphologies of asymmetric spiral arms and clumpy star-forming regions and to model the propagation of light through a dusty medium. Methods. In this paper, we present a new technique developed to model the radiative transfer effects in nearby face-on galaxies. We construct a high-resolution 3D radiative transfer model with the Monte-Carlo code SKIRT to account for the absorption, scattering, and non-local thermal equilibrium (NLTE) emission of dust in M 51. The 3D distribution of stars is derived from the 2D morphology observed in the IRAC 3.6 μm, GALEX FUV, Hα, and MIPS 24 μm wavebands, assuming an exponential vertical distribution with an appropriate scale height. The dust geometry is constrained through the far-ultraviolet (FUV) attenuation, which is derived from the observed total-infrared-to-far-ultraviolet luminosity ratio. The stellar luminosity, star formation rate, and dust mass have been scaled to reproduce the observed stellar spectral energy distribution (SED), FUV attenuation, and infrared SED.Results. The dust emission derived from RT calculations is consistent with far-infrared and submillimeter observations of M 51, implying that the absorbed stellar energy is balanced by the thermal re-emission of dust. The young stars provide 63% of the energy for heating the dust responsible for the total infrared emission (8−1000 μm), while 37% of the dust emission is governed through heating by the evolved stellar population. In individual wavebands, the contribution from young stars to the dust heating dominates at all infrared wavebands but gradually decreases towards longer infrared and submillimeter wavebands for which the old stellar population becomes a non-negligible source of heating. Upon extrapolation of the results for M 51, we present prescriptions for estimating the contribution of young stars to the global dust heating based on a tight correlation between the dust heating fraction and specific star formation rate.
Far-reaching dust distribution in galaxy discs Smith, Matthew W. L; Eales, Stephen A; De Looze, Ilse ...
Monthly notices of the Royal Astronomical Society,
10/2016, Letnik:
462, Številka:
1
Journal Article
Recenzirano
Odprti dostop
In most studies of dust in galaxies, dust is only detected from its emission to approximately the optical radius of the galaxy. By combining the signal of 110 spiral galaxies observed as part of the ...Herschel Reference Survey, we are able to improve our sensitivity by an order of magnitude over that for a single object. Here we report the direct detection of dust from its emission that extends out to at least twice the optical radius. We find that the distribution of dust is consistent with an exponential at all radii with a gradient of ∼−1.7 dex
$R_{25}^{-1}$
. Our dust temperature declines linearly from ∼25 K in the centre to 15 K at R
25 from where it remains constant out to ∼2.0 R
25. The surface density of dust declines with radius at a similar rate to the surface density of stars but more slowly than the surface density of the star-formation rate. Studies based on dust extinction and reddening of high-redshift quasars have concluded that there are substantial amounts of dust in intergalactic space. By combining our results with the number counts and angular correlation function from the SDSS, we show that with Milky Way-type dust we can explain the reddening of the quasars by the dust within galactic discs alone. Given the uncertainties in the properties of any intergalactic dust, we cannot rule out its existence, but our results show that statistical investigations of the dust in galactic haloes that use the reddening of high-redshift objects must take account of the dust in galactic discs.
The Herschel Virgo Cluster Survey Pappalardo, Ciro; Bizzocchi, Luca; Fritz, Jacopo ...
Astronomy and astrophysics (Berlin),
5/2016, Letnik:
589
Journal Article
Recenzirano
Odprti dostop
Context. The star formation rate is a crucial parameter for the investigation galaxy evolution. At low redshift the cosmic star formation rate density declines smoothly, and massive active galaxies ...become passive, reducing their star formation activity. This implies that the bulk of the star formation rate density at low redshift is mainly driven by low mass objects. Aims. We investigate the properties of a sample of low luminosity far-infrared sources selected at 250 mum. We have collected data from ultraviolet to far-infrared in order to perform a multiwavelengths analysis. The main goal is to investigate the correlation between star formation rate, stellar mass, and dust mass for a galaxy population with a wide range in dust content and stellar mass, including the low mass regime that most probably dominates the star formation rate density at low redshift. Methods. We define a main sample of ~800 sources with full spectral energy distribution coverage between 0.15 <lambda< 500 mum and an extended sample with ~5000 sources in which we remove the constraints on the ultraviolet and near-infrared bands. We analyze both samples with two different spectral energy distribution fitting methods: MAGPHYS and CIGALE, which interpret a galaxy spectral energy distribution as a combination of different simple stellar population libraries and dust emission templates. Results. In the star formation rate versus stellar mass plane our samples occupy a region included between local spirals and higher redshift star forming galaxies. These galaxies represent the population that at z< 0.5 quenches their star formation activity and reduces their contribution to the cosmic star formation rate density. The subsample of galaxies with the higher masses (Mlow *> 3 x 10 super(10)M sub(middot in circle)) do not lie on the main sequence, but show a small offset as a consequence of the decreased star formation. Low mass galaxies (Mlow *< 1 x 10 super(10)M sub(middot in circle)) settle in the main sequence with star formation rate and stellar mass consistent with local spirals. Conclusions. Deep Herschel data allow the identification of a mixed galaxy population with galaxies still in an assembly phase or galaxies at the beginning of their passive evolution. We find that the dust luminosity is the parameter that allow us to discriminate between these two galaxy populations. The median spectral energy distribution shows that even at low star formation rate our galaxy sample has a higher mid-infrared emission than previously predicted.
ABSTRACT
We present a CO(3–2) survey of selected regions in the M31 disc as part of the JCMT large programme, HARP and SCUBA-2 High-Resolution Terahertz Andromeda Galaxy Survey (HASHTAG). The 12 ...CO(3–2) fields in this survey cover a total area of 60 arcmin2, spanning a deprojected radial range of 2–14 kpc across the M31 disc. Combining these observations with existing IRAM 30 m CO(1–0) observations and JCMT CO(3–2) maps of the nuclear region of M31, as well as dust temperature and star formation rate surface density maps, we are able to explore the radial distribution of the CO(3–2)/CO(1–0) integrated intensity ratio (R31) and its relationship with dust temperature and star formation. We find that the value of R31 between 2 and 9 kpc galactocentric radius is 0.14, significantly lower than what is seen in the nuclear ring at 1 kpc (R31 ∼ 0.8), only to rise again to 0.27 for the fields centred on the 10 kpc star forming ring. We also found that R31 is positively correlated with dust temperature, with Spearman’s rank correlation coefficient ρ = 0.55. The correlation between star formation rate surface density and CO(3–2) intensity is much stronger than with CO(1–0), with ρ = 0.54 compared to –0.05, suggesting that the CO(3–2) line traces warmer and denser star forming gas better. We also find that R31 correlates well with star formation rate surface density, with ρ = 0.69.
Thanks to deep UV observations with GALEX and Swift, diffuse UV haloes have recently been discovered around galaxies. Based on UV-optical colours, it has been advocated that the UV haloes around ...spiral galaxies are due to UV radiation emitted from the disc and scattered off dust grains at high latitudes. Detailed UV radiative transfer models that take into account scattering and absorption can explain the morphology of the UV haloes, and they require the presence of an additional thick dust disc next the to traditional thin disc for half of the galaxies in their sample. We test whether such an additional thick dust disc agrees with the observed infrared emission in NGC 3628, an edge-on galaxy with a clear signature of a thick dust disc. We extend the far-ultraviolet radiative transfer models to full-scale panchromatic models. Our model, which contains no fine-tuning, can almost perfectly reproduce the observed spectral energy distribution from UV to mm wavelengths. These results corroborate the interpretation of the extended UV emission in NGC 3628 as scattering off dust grains, and hence of the presence of a substantial amount of diffuse extra-planar dust. A significant caveat, however, is the geometrical simplicity and non-uniqueness of our model: other models with a different geometrical setting could lead to a similar spectral energy distribution. More detailed radiative transfer simulations that compare the model results to images from UV to submm wavelengths are a way to break this degeneracy, as are UV polarisation measurements.
The Herschel Virgo Cluster Survey Pappalardo, Ciro; Bendo, George J; Bianchi, Simone ...
Astronomy and astrophysics (Berlin),
1/2015, Letnik:
573
Journal Article
Recenzirano
Odprti dostop
We present three independent catalogs of point-sources extracted from SPIRE images at 250, 350, and 500 mu m, acquired with the Herschel Space Observatory as a part of the Herschel Virgo Cluster ...Survey (HeViCS). The catalogs have been cross-correlated to consistently extract the photometry at SPIRE wavelengths for each object. Sources have been detected using an iterative loop. The source positions are determined by estimating the likelihood to be a real source for each peak on the maps, according to the criterion defined in the sourceExtractorSussextractor task. We calculate the completeness and the flux accuracy by injecting artificial sources in the timeline and estimate the reliability of the catalog using a permutation method. The number counts at 250, 350, and 500 mu m show an increase in the slope below 200 mJy, indicating a strong evolution in number of density for galaxies at these fluxes. Our iterative method for source identification allowed the detection of a family of 500 mu m sources that are not foreground objects belonging to Virgo and not found in other catalogs.
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