arXiv subjects

Aleksandr V. Mosenkov

Publications and source records attributed to Aleksandr V. Mosenkov.

At least 37 records · Page 2Linked to original sources

arXiv2023

Prospects for future studies using deep imaging: Analysis of individual Galactic cirrus filaments

The presence of Galactic cirrus is an obstacle for studying both faint objects in our Galaxy and low surface brightness extragalactic structures. With the aim of studying individual cirrus filaments in SDSS Stripe 82 data, we develop techniques based on machine learning and neural networks that allow one to isolate filaments from foreground and background sources in the entirety of Stripe 82 with a precision similar to that of the human expert. Our photometric study of individual filaments indicates that only those brighter than 26 mag arcsec$^{-2}$ in the SDSS $r$ band are likely to be identified in SDSS Stripe~82 data by their distinctive colours in the optical bands. We also show a significant impact of data processing (e.g. flat-fielding, masking of bright stars, and sky subtraction) on colour estimation. Analysing the distribution of filaments' colours with the help of mock simulations, we conclude that most filaments have colours in the following ranges: $0.55 \leq g-r \leq 0.73$ and $0.01 \leq r-i \leq 0.33$. Our work provides a useful framework for an analysis of all types of low surface brightness features (cirri, tidal tails, stellar streams, etc.) in existing and future deep optical surveys. For practical purposes, we provide the catalogue of dust filaments.

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arXiv2022

Isochrone fitting of Galactic globular clusters -- IV. NGC6362 and NGC6723

We present new isochrone fits to the colour-magnitude diagrams of the Galactic globular clusters NGC\,6362 and NGC\,6723. We utilize 22 and 26 photometric filters for NGC\,6362 and NGC\,6723, respectively, from the ultraviolet to mid-infrared using data sets from {\it HST}, {\it Gaia}, unWISE, and other photometric sources. We use models and isochrones from the Dartmouth Stellar Evolution Database (DSED) and Bag of Stellar Tracks and Isochrones (BaSTI) for $α$-enhanced [$α$/Fe]$=+0.4$ and different helium abundances. The metallicities [Fe/H]$=-1.04\pm0.07$ and $-1.09\pm0.06$ are derived from the red giant branch slopes in our fitting for NGC\,6362 and NGC\,6723, respectively. They agree with spectroscopic estimates from the literature. We find a differential reddening up to $ΔE(B-V)=0.13$ mag in the NGC\,6723 field due to the adjacent Corona Australis cloud complex. We derive the following for NGC\,6362 and NGC\,6723, respectively: distances $7.75\pm0.03\pm0.15$ (statistic and systematic error) and $8.15\pm0.04\pm0.15$ kpc; ages $12.0\pm0.1\pm0.8$ and $12.4\pm0.1\pm0.8$ Gyr; extinctions $A_\mathrm{V}=0.19\pm0.04\pm0.06$ and $0.24\pm0.03\pm0.06$ mag; reddenings $E(B-V)=0.056\pm0.01\pm0.02$ and $0.068\pm0.01\pm0.02$ mag. DSED provides systematically lower [Fe/H] and higher reddenings than BaSTI. However, the models agree in their relative estimates: NGC\,6723 is $0.44\pm0.04$ kpc further, $0.5\pm0.1$ Gyr older, $ΔE(B-V)=0.007\pm0.002$ more reddened, and with $0.05\pm0.01$ dex lower [Fe/H] than NGC\,6362. The lower metallicity and greater age of NGC\,6723 with respect to NGC\,6362 explain their horizontal branch morphology difference. This confirms age as the second parameter for these clusters. We provide lists of the cluster members from the {\it Gaia} Data Release 3.

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arXiv2022

The resolved scaling relations in DustPedia: Zooming in on the local Universe

We perform a homogeneous analysis of an unprecedented set of spatially resolved scaling relations (SRs) between ISM components and other properties in the range of scales 0.3-3.4 kpc. We also study some ratios: dust-to-stellar, dust-to-gas, and dust-to-metal. We use a sample of 18 large, spiral, face-on DustPedia galaxies. All the SRs are moderate/strong correlations except the dust-HI SR that does not exist or is weak for most galaxies. The SRs do not have a universal form but each galaxy is characterized by distinct correlations, affected by local processes and galaxy peculiarities. The SRs hold starting from 0.3 kpc, and if a breaking down scale exists it is < 0.3 kpc. By evaluating all galaxies at 3.4 kpc, differences due to peculiarities of individual galaxies are cancelled out and the corresponding SRs are consistent with those of whole galaxies. By comparing subgalactic and global scales, the most striking result emerges from the SRs involving ISM components: the dust-total gas SR is a good correlation at all scales, while the dust-H2 and dust-HI SRs are good correlations at subkpc/kpc and total scales, respectively. For the other explored SRs, there is a good agreement between small and global scales and this may support the picture where the main physical processes regulating the properties and evolution of galaxies occur locally. Our results are consistent with the hypothesis of self-regulation of the SF process. The analysis of subgalactic ratios shows that they are consistent with those derived for whole galaxies, from low to high z, supporting the idea that also these ratios could be set by local processes. Our results highlight the heterogeneity of galaxy properties and the importance of resolved studies on local galaxies in the context of galaxy evolution. They also provide observational constraints to theoretical models and updated references for high-z studies.

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arXiv2022

Unveiling the nature of polar-ring galaxies from deep imaging

General structural properties and low surface brightness tidal features hold important clues to the formation of galaxies. In this paper, we study a sample of polar-ring galaxies (PRGs) based on optical imaging from the Sloan Digital Sky Survey (SDSS) Stripe82 and other deep surveys. We investigate the deepest images of candidates for PRGs to date. We carry out photometric decomposition on the host galaxies and associated polar structures that allows us to derive the structural properties of both components. We are able to detect very faint tidal structures around most PRGs in our sample. For several galaxies, we can directly observe the formation of the polar ring due to merging, which is manifested in debris of the victim galaxy and an arc-like polar structure made up of its material. In a few cases, we can discern signs of tidal accretion. The results obtained indicate that the gravitational interaction and merging of galaxies are the most plausible mechanisms for the formation of polar-ring galaxies.

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arXiv2022

The distribution of dust in edge-on galaxies: I. The global structure

In this first paper in a series we present a study of the global dust emission distribution in nearby edge-on spiral galaxies. Our sample consists of 16 angularly large and 13 less spatially resolved galaxies selected from the DustPedia sample. To explore the dust emission distribution, we exploit the Herschel photometry in the range 100-500 $μ$m. We employ Sérsic and three-dimensional disc models to fit the observed two-dimensional profiles of the galaxies. Both approaches give similar results. Our analysis unequivocally states the case for the presence of extraplanar dust in between 6 to 10 large galaxies. The results reveal that both the disc scale length and height increase as a function of wavelength between 100 and 500 $μ$m. The dust disc scale height positively correlates with the dust disc scale length, similar to what is observed for the stellar discs. We also find correlations between the scale lengths and scale heights in the near- and far-infrared which suggest that the stellar discs and their dust counterparts are tightly connected. Furthermore, the intrinsic flattening of the dust disc is inversely proportional to the maximum rotation velocity and the dust mass of the galaxy: more massive spiral galaxies host, on average, relatively thinner dust discs. Also, there is a tendency for the dust-to-stellar scale height ratio to decrease with the dust mass and rotation velocity. We conclude that low-mass spiral galaxies host a diffuse, puffed-up dust disc with a thickness similar to that of the stellar disc.

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arXiv2021

Fractal dimension of optical cirrus in Stripe82

The geometric characteristics of dust clouds provide important information on the physical processes that structure such clouds. One of such characteristics is the $2D$ fractal dimension $D$ of a cloud projected onto the sky plane. In previous studies, which were mostly based on infrared (IR) data, the fractal dimension of individual clouds was found to be in a range from 1.1 to 1.7 with a preferred value of 1.2--1.4. In the present work, we use data from Stripe82 of the Sloan Digital Sky Survey to measure the fractal dimension of the cirrus clouds. This is done here for the first time for optical data with significantly better resolution as compared to IR data. To determine the fractal dimension, the perimeter-area method is employed. We also consider IR (IRAS and Herschel) counterparts of the corresponding optical fields to compare the results between the optical and IR. We find that the averaged fractal dimension across all clouds in the optical is $\langle D \rangle =1.69^{+0.05}_{-0.05}$ which is significantly larger then the fractal dimension of its IR counterparts $\langle D\rangle=1.38^{+0.07}_{-0.06}$. We examine several reasons for this discrepancy (choice of masking and minimal contour level, image and angular resolution, etc.) and find that for approximately half of our fields the different angular resolution (point spread function) of the optical and IR data can explain the difference between the corresponding fractal dimensions. For the other half of the fields, the fractal dimensions of the IR and visual data remain inconsistent, which can be associated with physical properties of the clouds, but further physical simulations are required to prove it.

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arXiv2021

Isochrone fitting of Galactic globular clusters -- III. NGC\,288, NGC\,362, and NGC\,6218 (M12)

We present new isochrone fits to colour-magnitude diagrams of the Galactic globular clusters NGC\,288, NGC\,362, and NGC\,6218 (M12). We utilize a lot of photometric bands from the ultraviolet to mid-infrared by use of data from the {\it HST}, {\it Gaia}, unWISE, Pan-STARRS, and other photometric sources. In our isochrone fitting we use theoretical models and isochrones from the Dartmouth Stellar Evolution Program and Bag of Stellar Tracks and Isochrones for $α$-enhanced abundance [$α$/Fe]$=+0.40$, different helium abundances, and a metallicity of about [Fe/H]$=-1.3$ adopted from the literature. We derive the most probable distances $8.96\pm0.05$, $8.98\pm0.06$, and $5.04\pm0.05$ kpc, ages $13.5\pm1.1$, $11.0\pm0.6$, and $13.8\pm1.1$ Gyr, extinctions $A_\mathrm{V}=0.08\pm0.03$, $0.11\pm0.04$, and $0.63\pm0.03$ mag, and reddenings $E(B-V)=0.014\pm0.010$, $0.028\pm0.011$, and $0.189\pm0.010$ mag for NGC\,288, NGC\,362, and NGC\,6218, respectively. The distance estimates from the different models are consistent, while those of age, extinction, and reddening are not. The uncertainties of age, extinction, and reddening are dominated by some intrinsic systematic differences between the models. However, the models agree in their relative age estimates: NGC\,362 is $2.6\pm0.5$ Gyr younger than NGC\,288 and $2.8\pm0.5$ Gyr younger than NGC\,6218, confirming age as the second parameter for these clusters. We provide reliable lists of the cluster members and precise cluster proper motions from the {\it Gaia} Early Data Release 3.

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arXiv2021

The structure of the Milky Way based on unWISE 3.4$μ$m integrated photometry

We present a detailed analysis of the Galaxy structure using an unWISE wide-field image at $3.4μ$m. We perform a 3D photometric decomposition of the Milky Way taking into account i) the projection of the Galaxy on the celestial sphere and ii) that the observer is located within the Galaxy at the solar radius. We consider a large set of photometric models starting with a pure disc model and ending with a complex model which consists of thin and thick discs plus a boxy-peanut-shaped bulge. In our final model, we incorporate many observed features of the Milky Way, such as the disc flaring and warping, several over-densities in the plane, and the dust extinction. The model of the bulge with the corresponding X-shape structure is obtained from N-body simulations of a Milky Way-like galaxy. This allows us to retrieve the parameters of the aforementioned stellar components, estimate their contribution to the total Galaxy luminosity, and constrain the position angle of the bar. The mass of the thick disc in our models is estimated to be 0.4-1.3 of that for the thin disc. The results of our decomposition can be directly compared to those obtained for external galaxies via multicomponent photometric decomposition.

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arXiv2021

Probing the spectral shape of dust emission with the DustPedia galaxy sample

The objective of this paper is to understand the variance of the far-infrared (FIR) spectral energy distribution (SED) of the DustPedia galaxies, and its link with the stellar and dust properties. An interesting aspect of the dust emission is the inferred FIR colours which could inform us about the dust content of galaxies, and how it varies with the physical conditions within galaxies. However, the inherent complexity of dust grains as well as the variety of physical properties depending on dust, hinder our ability to utilise their maximum potential. We use principal component analysis (PCA) to explore new hidden correlations with many relevant physical properties such as the dust luminosity, dust temperature, dust mass, bolometric luminosity, star-formation rate (SFR), stellar mass, specific SFR, dust-to-stellar mass ratio, the fraction of absorbed stellar luminosity by dust (f_abs), and metallicity. We find that 95% of the variance in our sample can be described by two principal components (PCs). The first component controls the wavelength of the peak of the SED, while the second characterises the width. The physical quantities that correlate better with the coefficients of the first two PCs, and thus control the shape of the FIR SED are: the dust temperature, the dust luminosity, the SFR, and f_abs. Finally, we find a weak tendency for low-metallicity galaxies to have warmer and broader SEDs, while on the other hand high-metallicity galaxies have FIR SEDs that are colder and narrower.

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arXiv2021

Quantified diffuse light in compact groups of galaxies

The vast majority of stars in galaxy groups are contained within their constituent galaxies. Some small fraction of stars is expected, however, to follow the global dark matter potential of the group. In compact groups, interactions between the galaxies should be frequent. This leads to a more intensive material stripping from the group members, which finally forms an intra-group light component (IGL). Therefore, the distribution of the IGL should be related to the distribution of the total mass in the compact group and its dynamical status. In this study we consider the distribution and fraction of the IGL in a sample of 36 Hickson compact groups (HCGs). We use deep observations of these compact groups (down to surface brightness $\sim 28$ mag\,arcsec$^{-2}$ in the $r$ band) obtained with the WISE $28$-inch telescope. For five HCGs with a bright symmetric IGL component, we carry out multicomponent photometric decomposition to simultaneously fit the galaxy profiles and the IGL. For the remaining groups, we only fit the profiles of their constituent galaxies. We find that the mean surface brightness of the IGL correlates with the mean morphology of the group: it becomes brighter in the groups with a larger fraction of early-type galaxies. On the other hand, the IGL brightness depends on the total luminosity of the group. The IGL profile tends to have a Sérsic index $n\sim0.5-1$, which is generally consistent with the mass density profile of dark matter haloes in compact groups obtained from cosmological simulations.

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arXiv2020

{\it Gaia} DR2 giants in the Galactic dust -- I. Reddening across the whole dust layer and some properties of the giant clump

We consider a complete sample of 101810 giants with Gaia DR2 parallaxes $\varpi$ within the red clump domain of the Hertzsprung-Russell diagram in the space cylinder with a radius of 700 pc around the Sun and a height of $|Z|=1800$ pc. We use the Gaia DR2 $G_\mathrm{BP}$, $G_\mathrm{RP}$ and WISE $W3$ photometry. We describe the spatial variations of the modes of the observables $G_\mathrm{BP}-G_\mathrm{RP}$, $G_\mathrm{RP}-W3$, $G_\mathrm{BP}+5+5\,\log_{10}\varpi$, $G_\mathrm{RP}+5+5\,\log_{10}\varpi$, and $W3+5+5\,\log_{10}\varpi$ by extinction and reddening in combination with linear vertical gradients of the intrinsic colours and absolute magnitudes of the red giant clump. The derived clump median absolute magnitude in $W3$ agrees with its recent literature estimates. The clump median intrinsic colours and absolute magnitudes in $G_\mathrm{BP}$ and $G_\mathrm{RP}$ are derived for the first time at a precision level of 0.01 mag. We confirm the reliability of the derived clump absolute magnitudes, intrinsic colours, and their vertical gradients by comparing them with the theoretical predictions from PARSEC, MIST and BaSTI isochrones. This leads us to the median age and [Fe/H] of the clump within $|Z|<1.7$ kpc from the Galactic mid-plane as $(2.3\pm0.5)+(3.2\pm1.6)\,|Z|$ Gyr and $(-0.08\pm0.08)-(0.16\pm0.07)\,|Z|$ dex, respectively, where $Z$ is expressed in kpc. These results agree with recent empirical and theoretical estimates. Moreover, all the models give similar age-metallicity relations by use of our results in the optical range. The derived extinctions and reddenings across the whole dust half-layer below or above the Sun converge to the reddening $E(B-V)=0.06$ mag by use of the most reliable extinction laws.

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arXiv2020

High-resolution, 3D radiative transfer modelling V. A detailed model of the M51 interacting pair

Investigating the dust heating mechanisms in galaxies provides a deeper understanding of how the internal energy balance drives their evolution. Over the last decade, radiative transfer simulations based on the Monte Carlo method have underlined the role of the various stellar populations heating the diffuse dust. Beyond the expected heating through ongoing star formation, both older stellar population (> 8Gyr) and even AGN can contribute energy to the infrared emission of diffuse dust. Here, we examine how the radiation of an external heating source, like the less massive galaxy NGC5195, in the M51 interacting system, could affect the heating of the diffuse dust of its parent galaxy, NGC5194, and vice versa. To quantify the exchange of energy between the two galaxies we use SKIRT, a state-of-the-art Monte Carlo radiative transfer code. In the interest of modelling, the assumed centre-to-centre distance separation between the two galaxies is 10kpc. Our model reproduces the global SED of the system, and it closely matches the observed images. In total, 40.7% of the intrinsic stellar radiation of the combined system is absorbed by dust. Furthermore, we quantify the contribution of the various dust heating sources in the system, and find that the young stellar population of NGC5194 is the predominant dust-heating agent, with a global heating fraction of 71.2%. Another 23% is provided by the older stellar population of the same galaxy, while the remaining 5.8% has its origin in NGC5195. Locally, we find that the regions of NGC5194 closer to NGC5195 are significantly affected by the radiation field of the latter, with the absorbed energy fraction rising up to 38%. The contribution of NGC5195 remains under the percentage level in the outskirts of the disc of NGC5194. This is the first time that the heating of the diffuse dust by a companion galaxy is quantified in a nearby interacting system.

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arXiv2020

Nonparametric galaxy morphology from UV to submm wavelengths

We present the first nonparametric morphological analysis of a set of spiral galaxies from UV to submm wavelengths. Our study is based on high-quality multi-wavelength imaging for nine well-resolved spiral galaxies from the DustPedia database, combined with nonparametric morphology indicators calculated in a consistent way using the {\tt{StatMorph}} package. We measure the half-light radius, the concentration index, the asymmetry index, the smoothness index, the Gini coefficient and the $M_{20}$ indicator in various wavebands from UV to submm wavelengths, as well as in stellar mass, dust mass and star formation rate maps. We find that the interstellar dust in galaxies is distributed in a more extended, less centrally concentrated, more asymmetric, and more clumpy way than the stars. This is particularly evident when comparing morphological indicators based on the stellar mass and dust mass maps. This should serve as a warning sign against treating the dust in galaxies as a simple smooth component. We argue that the nonparametric galaxy morphology of galaxies from UV to submm wavelengths is an interesting test for cosmological hydrodynamics simulations.

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arXiv2020

Tilted outer and inner structures in edge-on galaxies?

Tilted and warped discs inside tilted dark matter haloes are predicted from numerical and semi-analytical studies. In this paper, we use deep imaging to demonstrate the likely existence of tilted outer structures in real galaxies. We consider two SB0 edge-on galaxies, NGC4469 and NGC4452, which exhibit apparent tilted outer discs with respect to the inner structure. In NGC4469, this structure has a boxy shape, inclined by $Δ$PA$\approx$3$^{\circ}$ with respect to the inner disc, whereas NGC4452 harbours a discy outer structure with $Δ$PA$\approx$6$^{\circ}$. In spite of the different shapes, both structures have surface brightness profiles close to exponential and make a large contribution ($\sim30$%) to the total galaxy luminosity. In the case of NGC4452, we propose that its tilted disc likely originates from a former fast tidal encounter (probably with IC3381). For NGC4469, a plausible explanation may also be galaxy harassment, which resulted in a tilted or even a tumbling dark matter halo. A less likely possibility is accretion of gas-rich satellites several Gyr ago. New deep observations may potentially reveal more such galaxies with tilted outer structures, especially in clusters. We also consider galaxies, mentioned in the literature, where a central component (a bar or a bulge) is tilted with respect to the stellar disc. According to our numerical simulations, one of the plausible explanations of such observed "tilts" of the bulge/bar is a projection effect due to a not exactly edge-on orientation of the galaxy coupled with a skew angle of the triaxial bulge/bar.

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arXiv2020

High-resolution, 3D radiative transfer modelling. II. The early-type spiral galaxy M81

Interstellar dust absorbs stellar light very efficiently and thus shapes the energetic output of galaxies. Studying the impact of different stellar populations on the dust heating remains hard because it requires decoupling the relative geometry of stars and dust, and involves complex processes as scattering and non-local dust heating. We aim to constrain the relative distribution of dust and stellar populations in the spiral galaxy M81 and create a realistic model of the radiation field that describes the observations. Investigating the dust-starlight interaction on local scales, we want to quantify the contribution of young and old stellar populations to the dust heating. We aim to standardise the setup and model selection of such inverse radiative transfer simulations so this can be used for comparable modelling of other nearby galaxies. We present a semi-automated radiative transfer modelling pipeline that implements the necessary steps such as the geometric model construction and the normalisation of the components through an optimisation routine. We use the Monte Carlo radiative transfer code SKIRT to calculate a self-consistent, panchromatic model of the interstellar radiation field. By looking at different stellar populations independently, we can quantify to what extent different stellar age populations contribute to the dust heating. Our method takes into account the effects of non-local heating. We obtain a realistic 3D radiative transfer model of the face-on galaxy M81. We find that only 50.2\% of the dust heating can be attributed to young stellar populations. We confirm a tight correlation between the specific star formation rate and the heating fraction by young stellar populations, both in sky projection and in 3D, also found for radiative transfer models of M31 and M51. We conclude that... (abridged)

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arXiv2020

High-resolution, 3D radiative transfer modelling III. The DustPedia barred galaxies

Context: Dust in late-type galaxies in the local Universe is responsible for absorbing approximately one third of the energy emitted by stars. It is often assumed that dust heating is mainly attributable to the absorption of UV and optical photons emitted by the youngest (<= 100 Myr) stars. Consequently, thermal re-emission by dust at FIR wavelengths is often linked to the star-formation activity of a galaxy. However, several studies argue that the contribution to dust heating by much older stars might be more significant. Advances in radiation transfer (RT) simulations finally allow us to actually quantify the heating mechanisms of diffuse dust by the stellar radiation field. Aims: As one of the main goals in the DustPedia project, we have constructed detailed 3D stellar and dust RT models for nearby galaxies. We analyse the contribution of the different stellar populations to the dust heating in four face-on barred galaxies: NGC1365, M83, M95, and M100. We aim to quantify the fraction directly related to young stars, both globally and on local scales, and to assess the influence of the bar on the heating fraction. Results: We derive global attenuation laws for each galaxy and confirm that galaxies of high sSFR have shallower attenuation curves and weaker UV bumps. On average, 36.5% of the bolometric luminosity is absorbed by dust. We report a clear effect of the bar structure on the radial profiles of the dust-heating fraction by the young stars, and the dust temperature. We find that the young stars are the main contributors to the dust heating, donating, on average ~59% of their luminosity to this purpose throughout the galaxy. This dust-heating fraction drops to ~53% in the bar region and ~38% in the bulge region where the old stars are the dominant contributors to the dust heating. We also find a strong link between the heating fraction by the young stars and the sSFR.

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arXiv2020

Reproducing the Universe: a comparison between the EAGLE simulations and the nearby DustPedia galaxy sample

We compare the spectral energy distributions (SEDs) and inferred physical properties for simulated and observed galaxies at low redshift. We exploit UV-submillimetre mock fluxes of ~7000 z=0 galaxies from the EAGLE suite of cosmological simulations, derived using the radiative transfer code SKIRT. We compare these to ~800 observed galaxies in the UV-submillimetre range, from the DustPedia sample of nearby galaxies. To derive global properties, we apply the SED fitting code CIGALE consistently to both data sets, using the same set of ~80 million models. The results of this comparison reveal overall agreement between the simulations and observations, both in the SEDs and in the derived physical properties, with a number of discrepancies. The optical and far-infrared regimes, and the scaling relations based upon the global emission, diffuse dust and stellar mass, show high levels of agreement. However, the mid-infrared fluxes of the EAGLE galaxies are overestimated while the far-UV domain is not attenuated enough, compared to the observations. We attribute these discrepancies to a combination of galaxy population differences between the samples, and limitations in the subgrid treatment of star-forming regions in the EAGLE-SKIRT post-processing recipe. Our findings show the importance of detailed radiative transfer calculations and consistent comparison, and provide suggestions for improved numerical models.

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arXiv2019

The ISM scaling relations in DustPedia late-type galaxies: A benchmark study for the Local Universe

The purpose of this work is the characterization of the main scaling relations between all the ISM components (dust, atomic/molecular/total gas), gas-phase metallicity, and other galaxy properties, such as Mstar and galaxy morphology, for late-type galaxies in the Local Universe. This study is performed by extracting late-type galaxies from the entire DustPedia sample and by exploiting the large and homogeneous dataset available thanks to the DustPedia project. The sample consists of 436 galaxies with morphological stage from T = 1 to 10, Mstar from 6 x 10^7 to 3 x 10^11 Msun, SFR from 6 x 10^(-4) to 60 Msun/yr, and 12 + log(O/H) from 8 to 9.5. The scaling relations involving the molecular gas are studied by assuming both a constant and a metallicity-dependent XCO. The analysis has been performed by means of the survival analysis technique. We confirm that the dust mass correlates very well with the total gas mass, and find -- for the first time -- that the dust mass correlates better with the atomic gas mass than the molecular one. We characterize important mass ratios such as gas fraction, molecular-to-atomic gas mass ratio, dust-to-total gas mass ratio (DGR), and dust-to-stellar mass ratio. Only the assumption of a metallicity-dependent XCO reproduces the expected decrease of the DGR with increasing morphological stage and decreasing gas-phase metallicity, with a slope of about 1. DGR, gas-phase metallicity, and the dust-to-stellar mass ratio are, for our galaxy sample, directly linked to the galaxy morphology. The molecular-to-atomic gas mass ratio and the DGR show a positive correlation for low molecular gas fractions, but for molecular gas rich galaxies this trend breaks down. This trend has never been found previously, to our knowledge. It provides new constraints for theoretical models of galaxy evolution and a reference for high-redshift studies.

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