Maritza A. Lara-Lopez

Context. We present a detailed multi-wavelength analysis of the nearby spiral galaxy NGC 6946, combining optical integral field spectroscopy (GCMS), infrared ( Herschel ), and radio observations (THINGS and HERACLES). Aims. We aim to characterise both the integrated and spatially resolved properties of the stellar populations and interstellar medium (ISM), and to interpret them in the context of bar-driven galaxy evolution. Methods. We used the spectral energy distribution fitting code SINOPSIS to derive stellar population properties (stellar mass, star formation history), and different prescriptions to derive ISM properties including atomic and molecular gas masses and the dust mass, dust temperature, and dust emissivity index, combining optical, infrared, and radio datasets. Results. We find that the central ∼2.6 kpc (∼0.2 R ₂₅ ) hosts ∼40% of the stellar mass, as well as the bulk of the molecular gas and dust, and has sustained enhanced star formation over cosmic time. A major star formation episode occurred ∼0.6 Gyr ago. The spatially resolved Kennicutt–Schmidt relation shows that molecular gas alone explains only part of the current SFR variance, while alternative prescriptions incorporating stellar mass and dynamical equilibrium pressure yield only modest improvements. We also find radial enhancements in the effective oxygen yield, Y _eff , and gas mass fraction, μ , relative to surrounding regions, consistent with sustained gas accumulation. Together with the molecular gas streaming motions previously detected in CO and H α kinematic studies, our results are consistent with, and provide independent support for, the inward transport of gas driven by a system of nested bars. Conclusions. Our results are consistent with a scenario in which a recent episode of bar-driven gas inflow enhanced the central molecular gas reservoir and sustained elevated star formation, further supported by the elevated gas-to-dust ratio in the inner region, and the low global M _HI / M H ₂ ratio. These findings point to efficient HI-to-H ₂ conversion, likely promoted by the combined effect of the secondary bar and the large dust content, ultimately regulating star formation. We also find indications consistent with a young stellar bar, given by the presence of a low-mass pseudo-bulge. The current decline in star formation despite large gas reservoirs suggests recent bar-driven quenching.

Context. Understanding the interstellar medium (ISM) requires high-resolution, multi-component mapping to capture its complex physical structure. Nearby spiral galaxies, with their abundant and diverse ISM, provide an ideal laboratory for such a comprehensive analysis at sub-galactic scales. Aims. We investigate dust-to-gas and dust-to-metal ratios (DGR and DMR) as functions of the gas-phase metallicity ( Z ) on spatial scales ranging from 0.6 to 2.3 kpc, in a sample of ten nearby spiral galaxies spanning more than an order of magnitude in stellar mass (9.7 ≤ log( M _* / M _⊙ )≤11.0), star formation rate (SFR, ∼0.3–3 M _⊙ yr ⁻¹ ), and metallicity ranging from 8.3 ≲ 12 + log(O/H) ≲ 8.8. We explore how the DGR– Z and DMR– Z relations are shaped by the assumptions behind the CO-to-H ₂ conversion factor ( α _CO ). Methods. We homogeneously combined maps of dust, atomic gas, molecular gas, and metallicity. Motivated by the diversity in L _{CO(1 − 0)} /SFR ratios and metallicity across our sample, we introduced a hybrid α _CO prescription to distinguish between CO-bright and CO-dark regimes. The derived DGR– Z and DMR– Z relations were compared with other global and resolved observational results, and with the predictions of dust and chemical evolution models. Results. Both DGR– Z and DMR– Z relations are dependent on the adopted α _CO prescription, and no single α _CO can reproduce the properties of the entire sample, motivating the use of a hybrid approach. The DGR increases with metallicity, spanning ∼1 dex across the sampled range, while the DMR remains approximately constant at log(DMR) = − 0.53 ± 0.13, implying that ∼30% of metals are locked into dust grains. This flat behaviour indicates an evolved dust phase where efficient ISM grain growth drives a saturation regime balancing dust formation and destruction.

Context . Radio continuum emission has the potential to be useful as an extinction-free tracer of star formation. However, the relation between the radio continuum luminosity and star formation rate (SFR) is potentially limited by various effects such as cosmic-ray transport, free-free absorption, and cosmic-ray electron energy losses. Aims . We aim to calibrate the radio-SFR relation in a sample of nearby galaxies ranging from dwarf to spiral galaxies, covering nearly five orders of magnitude in terms of the SFR range. We include both global and local measurements from individual and spatially resolved, kiloparsec-sized galaxies, respectively. Methods . We measured the radio continuum luminosities at 144 MHz using observations with the LOw Frequency ARray (LOFAR) and measured the radio spectral indices using ancillary 1.4 GHz data. We selected 70 nearby (distance d < 30 Mpc) galaxies, 15 of which were used for local measurements. Taking advantage of their rich ancillary data, we carried out a study of the radio-SFR relation using the total infrared (TIR), mid-infrared (MIR), H α , and far-ultraviolet (FUV) as complementary SFR tracers. About a third of our sample is made up of at least moderately star-forming edge-on galaxies with the remaining ones chosen to form a representative sample of a wide range of morphological types and SFR values. Results . For the first time, we show that the radio luminosity ( L ₁₄₄ ), the SFR, and the radio spectral index ( α ) define a ‘fundamental plane’ in the [log( L ₁₄₄ ), log(SFR), α ] space. This enables us to define a unified radio-SFR relation that is applicable to both for global and local data when using the radio spectral index as a secondary parameter. Conclusions . A unified radio-SFR relation for both global and local data could serve as a litmus test for galaxy simulations that include the effect of cosmic rays and magnetic fields. It also strengthens the case for using the radio-SFR relation as an extinction-free tracer of star formation.

Aims. This paper describes the relationship between the star formation rate and the stellar mass, the so-called main sequence (MS), of low-mass galaxies at three different redshifts from the OTELO survey. In particular, we study H α at z = 0.38, [O III ] at z = 0.83, and [O II ] at z = 1.43 emission line galaxies (ELGs). This is done to characterise the properties of low-mass ELGs. Methods. We fitted the spectral energy distribution (SED) of each emitter and obtained the stellar masses, the total infrared luminosity, and the star formation rate. We found that 100% of the H α emitters and about 90% of the [O III ] and [O II ] emitters are low-mass galaxies (< 10 ¹⁰ M _⊙ ). We generated a MS for each redshift regime, employing all galaxies and binning them in stellar mass. We obtained the parameters of the fit (turnover mass and slope of the low-mass regime) and compared them to results from the literature. Results. We found that the colour–magnitude method employed to select ELGs leaves out a significant number of them. We also found that the whole sample contains few luminous infrared galaxies and no ultra-luminous infrared galaxies. We also found that the lack of infrared constraints in the input SEDs may generate problems when determining the total infrared luminosity. When comparing the MS obtained for our sample of low-mass ELGs with those from the bibliography, we found, in general, very good agreement. We can consider the MS to be almost the same for the relatively unexplored regime of low-mass galaxies. However, the turnover mass obtained by this work is higher for all redshifts compared with the ones from the literature. We suggest that this is an effect of the different methods and samples used in the generation of the MS compared to those of the bibliography.

We present the results of a comprehensive survey conducted among members of the Spanish Astronomical Society (Sociedad Espanola de Astronomia, SEA) to assess well-being, professional satisfaction, and family-work balance of researchers in astronomy. The survey addressed multiple aspects of professional life, including happiness, career stability, publication pressure, and access to childcare services during scientific meetings. Responses were examined across gender and career stages to identify trends and sources of dissatisfaction.

Context. Galaxy clusters are among the largest and densest structures in the Universe. Their high density generally increases the suppression of star formation, known as quenching, altering galaxy properties. Aims. We study the quenching of emission-line galaxies (ELGs) in the rich cluster ZwCl 0024.0+1652 (Cl0024) at redshift z ∼ 0.4, aiming to determine if and how star formation is suppressed. Methods. Using multi-object spectroscopy from the GLACE survey, we extracted fluxes and redshifts of [O II ] λλ 3727, 3729, H β , and [O III ] λ 5007 emission lines to derive star formation rates (SFRs) for 173 ELGs. We also performed spectral energy distribution fitting to obtain key evolutionary parameters such as stellar masses ( M _⋆ ) and the 4000 Å break ( D 4000) index. Results. We derived the M _⋆ − SFR relation for 98 star-forming galaxies (SFGs), finding 34.7% exhibit suppressed SFRs in the cluster, compared to 11.0% in the field. While the SFRs show no significant variation with local density, the fraction of SFGs is 1.55 times higher in the cluster outskirts than in intermediate-density regions. The specific SFR decreases strongly with D 4000 for active SFGs but remains constant for suppressed galaxies. The fraction of suppressed galaxies in the infall region is 2.6 times higher than in the core, especially in the infalling structure B of the cluster. The cluster’s total mass does not appear to be a key factor in SFG quenching. Conclusions. Star formation in Cl0024 galaxies is suppressed by the dense cluster environment. This suppression is evident in SFG fractions and parameters tracing long-term evolution, indicating prolonged quenching. The SFGs preferentially reside in low-density regions, while suppressed galaxies dominate the infall region, supporting a ‘delayed-then-rapid’ quenching scenario.

Aims. This paper explores and analyses the gas metallicity gradients in a sample of 25 nearby galaxies using new integral field spectroscopy observations from the Metal-THINGS survey, for a total of 102 individual pointings. We derive and analyse the resolved diffuse ionised gas content, Baldwin, Phillips, & Terlevich diagrams, and gas metallicities for our entire sample, at spatial resolutions of 40–300 pc. Gas metallicity gradients are studied as a function of the galaxy’s stellar mass, H I gas fraction, and diffuse ionised gas content, and using different parametric length scales for normalisation. Methods. The metallicity gradients are analysed using Bayesian statistics based on data from the Metal-THINGS survey. Bayesian MCMC models are developed to explore how metallicity gradients vary with a galaxy’s mass and how they correlate with properties such as the stellar mass or the atomic gas fraction. Additionally, we compare and contrast our results with those from other works that use the same metallicity calibration. Results. For our sample, we find that the metallicity typically decreases with galactic radius, consistent with inside-out galaxy growth. We find a trend dependent on the stellar mass, with a break at log(M_star/M_⊙)≃9.5, and another between the metallicity gradients and the atomic gas fraction (f_{g,  H I}) of a galaxy at f_{g,  H I} ≃ 0.75, indicating shallower gradients for lower gas fractions. These results are consistent with previous studies on galaxies with comparable stellar mass regimes and morphologies. We find that normalisation using NUV-band effective radii is preferable for galaxies with a higher atomic gas content and lower stellar masses, while r-band radii are better suited for those with lower atomic gas fractions and more massive ones. Conclusions. Our results highlight a strong connection between gas content, stellar mass, and metallicity gradients. The breaks at log(M_⋆/M_⊙)≃9.5 and f_{g,  H I} ≃ 0.75 mark shifts in chemical enrichment behaviour, with low-mass galaxies showing greater sensitivity to gas processes. Overall, this points to gas accretion and removal as key drivers of chemical evolution in low-mass systems.

Context. Dust is a fundamental component of the interstellar medium (ISM) and plays a critical role in shaping galaxy evolution. Dust grains influence the ISM by cooling the gas, altering its chemistry, absorbing stellar radiation, and re-emitting it at longer wavelengths in the FIR and submillimetre (sub-mm) regimes. The cold dust component, which constitutes the majority of the dust mass, is primarily heated by stellar radiation, with contributions from both young, massive stars and the diffuse emission from older stellar populations. It is essential to discern how dust is heated to better understand the relationship between stellar populations and their surrounding environments. Aims. This study aims to identify the dominant heating mechanisms responsible for the cold dust component in typical nearby spiral galaxies and to explore the contributions of both young and evolved stellar populations to dust heating. Methods. Using a sample of 18 large, face-on spiral galaxies from the DustPedia project, we employed two complementary approaches. In the first method, we studied the correlations between the dust temperature (T_dust), star-formation rate (SFR) surface density (Σ_SFR), and stellar mass surface density (ΣM_*). In the second method, we explored the relationship between T_dust and the dust mass surface density (Σ_dust). Results. By analyzing the median temperature radial profile, we find that T_dust peaks at ∼24 K at the galaxy centre, decreasing to ∼15 K toward the galaxy outskirts. Our analysis shows similar T_dust in galaxies with and without a central active galactic nucleus (AGN), suggesting that AGN activity does not significantly influence T_dust values and distribution on the spatial scales covered by our data, which range from 0.3 to 3 kpc. For ∼72% of the galaxies in our sample, the methods consistently identify the primary dust heating source. However, when considering the entire galaxy sample, our analysis suggests that there is no single dominant heating mechanism. We find that both young and evolved stars contribute to dust heating, with their relative contributions varying across galaxies.

Context. The stellar mass−metallicity (M_⋆–Z) and stellar mass−star formation rate (M_⋆–SFR) relations are fundamental tools for understanding the evolution of star-forming (SF) galaxies. Combined with environmental factors, these relations provide valuable insights into how galaxies evolve. Aims. We analysed the M_⋆–Z and M_⋆–SFR relations for SF galaxies, classified according to their environment, and compared them with a control sample of field galaxies. The aim was to quantify the differences in metallicity (ΔZ) and star formation rate (ΔSFR) among galaxies in different environments. To achieve this, we used data from the Galaxy And Mass Assembly (GAMA) survey, along with the filament catalogue that classifies galaxies into filaments, tendrils, and voids. Methods. The emission lines were corrected for dust extinction, SF galaxies were selected using the BPT diagram, and their Z and SFR were estimated. Control samples were created for each type of environment, using field galaxies. The M_⋆–Z and M_⋆–SFR relations were fitted using Bayesian and least-squares methods. The scaling relations for galaxies in different environments were compared to their corresponding control samples to establish robust differences. Results. We determined that ΔZ increases as environments become denser. On the contrary, ΔSFR increases as environments become less dense. Both results demonstrate significant differences between filaments and tendrils compared to voids. We also analysed galaxies in filaments and tendrils that do not belong to any group, and found little to no difference compared to their control sample. Morphology showed no significant deviation from the control sample. Conclusions. We find that galaxies in filaments and tendrils have higher metallicities and lower SFRs due to enriched environments, while void galaxies sustain high SFRs with low metallicities, likely driven by isolation and cold gas accretion. Our results indicate that local environmental factors, rather than large-scale structure, are the primary drivers of these differences.