Oscar Cavichia de Moraes
@unifei.edu.br
Instituto de Física e Química
Universidade Federal de Itajubá
RESEARCH, TEACHING, or OTHER INTERESTS
Astronomy and Astrophysics
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
A. F. S. Cardoso, O. Cavichia, M. Mollá, and L. Sánchez-Menguiano
American Astronomical Society
Abstract The study of chemical evolution is of paramount importance for understanding the evolution of galaxies. Models and observations propose an inside-out mechanism in the formation of spiral galaxy disks, implying a negative radial gradient of elemental abundances when represented on a logarithmic scale. However, in some instances, the observed chemical abundance gradients deviate from a single negative straight line, revealing inner drops or outer flattenings, particularly in more massive galaxies. This study analyzes oxygen abundance gradients in spiral galaxies based on observations from the Calar Alto Legacy Integral Field Area survey. Our focus is specifically on examining oxygen abundance gradient profiles, as obtained with data from H ii regions, with a special emphasis on the inner radial gradient. We employ an automated fitting procedure to establish correlations between the physical properties of galaxies and bulges and the presence of these inner drops, seeking potential explanations for these variations in gradient. We find that the different criteria used in the literature to distinguish H ii regions from other ionization sources in the galaxies, such as active galactic nuclei, significantly impact the results, potentially altering abundance gradient profiles and uncovering galaxies with distinct inner drops. Additionally, we analyze the abundance radial gradients to investigate the impact of diffuse ionized gas (DIG) decontamination on oxygen abundances over these inner drops. We observe that DIG, concentrated mainly in the central regions of galaxies, can modify oxygen abundance gradient profiles if left unaddressed.
O Cavichia, M Mollá, J J Bazán, A Castrillo, L Galbany, I Millán-Irigoyen, Y Ascasibar, A I Díaz, and H Monteiro
Oxford University Press (OUP)
ABSTRACT The role of type Ia supernovae (SN Ia), mainly the delay time distributions (DTDs) determined by the binary systems, and the yields of elements created by different explosion mechanisms, are studied by using the MulChem chemical evolution model applied to our Galaxy. We explored 15 DTDs and 12 tables of elemental yields produced by different SN Ia explosion mechanisms, doing a total of 180 models. Chemical abundances for $\\alpha$-elements (O, Mg, Si, and Ca) and Fe derived from these models are compared with recent solar region observational data of $\\alpha$-elements over Fe relative abundances, [X/Fe], as a function of [Fe/H] and age. A multidimensional maximum-likelihood analysis shows that 52 models are able to fit all these data sets simultaneously, considering the 1$\\sigma$ confidence level. The combination of STROLG1 DTD from Strolger et al. (2020) and LN20181 SN Ia yields from Leung & Nomoto (2018) provides the best fit. The exponential model with very prompt events is a possible DTD, but a combination of several channels is more probable. The SN Ia yields that include MCh or Near MCh correspond to 39 (75 per cent) of the 52 best models. Regarding the DTD, 31 (60 per cent) of the 52 most probable models correspond to the SD scenario, while the remaining 21 (40 per cent) are based on the DD scenario. Our results also show that the relatively large dispersion of the observational data may be explained by the stellar migration from other radial regions, and/or perhaps a combination of DTDs and explosion channels.
O Cavichia, M Mollá, and J J Bazán
Oxford University Press (OUP)
ABSTRACT Due to its proximity, the stellar populations of the Galactic bulge (GB) can be resolved and can be studied in detail. This allows tracing the bulge metallicity distribution function (MDF) for different spatial regions within the bulge, which may give us clues about the bulge formation and evolution scenarios. In this work, we developed a chemical evolution model (CEM), taking into account the mass distribution in the bulge and disc, to derive the radial dependence of this time-scale in the Galaxy. Since the infall rate depends on that time-scale in the CEM, the results of the model were used to test a scenario where the bulge is formed inside-out. The obtained results for the [α/Fe] versus [Fe/H] relationship, the MDF and the [Fe/H] radial gradient in the bulge have been compared to available data in the literature. The model is able to reproduce most of the observational data: the spread in the relation [α/Fe] versus [Fe/H], the MDF shape in different regions of the bulge, the [Fe/H] radial gradient inside it, and the age–metallicity relation, as well as the [α/Fe] evolution with age. The results of the model point to a scenario where the bulk of the bulge stars pre-existed the boxy/peanut X-shape bar formation. As a result, the classical origin of the GB is not ruled out, and this scenario may be invoked to explain the chemical properties of the GB.
M Mollá, S Wekesa, O Cavichia, Á I Díaz, B K Gibson, F F Rosales-Ortega, Y Ascasibar, D S Wamalwa, and S F Sánchez
Oxford University Press (OUP)
ABSTRACT We present a 2D chemical evolution code applied to a Milky Way type Galaxy, incorporating the role of spiral arms in shaping azimuthal abundance variations, and confront the predicted behaviour with recent observations taken with integral field units. To the usual radial distribution of mass, we add the surface density of the spiral wave and study its effect on star formation and elemental abundances. We compute five different models: one with azimuthal symmetry which depends only on radius, while the other four are subjected to the effect of a spiral density wave. At early times, the imprint of the spiral density wave is carried by both the stellar and star formation surface densities; conversely, the elemental abundance pattern is less affected. At later epochs, however, differences among the models are diluted, becoming almost indistinguishable given current observational uncertainties. At the present time, the largest differences appear in the star formation rate and/or in the outer disc (R ≥ 18 kpc). The predicted azimuthal oxygen abundance patterns for t ≤ 2 Gyr are in reasonable agreement with recent observations obtained with VLT/MUSE for NGC 6754.
Enos Picazzio, Igor V. Luk’yanyk, Oleksandra V. Ivanova, Evgenij Zubko, Oscar Cavichia, Gorden Videen, and Sergei M. Andrievsky
Elsevier BV
M Mollá, Á I Díaz, O Cavichia, B K Gibson, W J Maciel, R D D Costa, Y Ascasibar, and C G Few
Oxford University Press (OUP)
© 2018 The Author(s). We study the evolution of oxygen abundance radial gradients as a function of time for the Milky Way Galaxy obtained with our MulChem chemical evolution model. We review the recent data of abundances for different objects observed in our Galactic disc. We analyse with our models the role of the growth of the stellar disc, as well as the effect of infall rate and star formation prescriptions, or the pre-enrichment of the infall gas, on the time evolution of the oxygen abundance radial distribution. We compute the radial gradient of abundances within the disc, and its corresponding evolution, taking into account the disc growth along time. We compare our predictions with the data compilation, showing a good agreement. Our models predict a very smooth evolution when the radial gradient is measured within the optical disc with a slight flattening of the gradient from ∼-0.057 dex kpc-1 at z = 4 until values around ∼-0.015 dex kpc-1 at z = 1 and basically the same gradient until the present, with small differences between models. Moreover, some models show a steepening at the last times, from z = 1 until z = 0 in agreement with data which give a variation of the gradient in a range from -0.02 to -0.04 dex kpc-1 from t = 10 Gyr until now. The gradient measured as a function of the normalized radius R/Reff is in good agreement with findings by CALIFA and MUSE, and its evolution with redshift falls within the error bars of cosmological simulations.
Oleksandra V. Ivanova, Enos Picazzio, Igor V. Luk'yanyk, Oscar Cavichia, and Sergei M. Andrievsky
Elsevier BV
W. J. Maciel, R. D. D. Costa, and O. Cavichia
IOP Publishing
Photoionized nebulae, comprising HII regions and planetary nebulae, are excellent laboratories to investigate the nucleosynthesis and chemical evolution of several elements in the Galaxy and other galaxies of the Local Group. Our purpose in this investigation is threefold: (i) to compare the abundances of HII regions and planetary nebulae in each system in order to investigate the differences derived from the age and origin of these objects, (ii) to compare the chemical evolution in different systems, such as the Milky Way, the Magellanic Clouds, and other galaxies of the Local Group, and (iii) to investigate to what extent the nucleosynthesis contributions from the progenitor stars affect the observed abundances in planetary nebulae, especially for oxygen and neon, which places constraints on the amount of these elements that can be produced by intermediate mass stars.
M. Mollá, O. Cavichia, B. Gibson, P. Tissera, P. Sánchez-Blázquez, A. I. Díaz, Y. Ascasibar, C. G. Few, S. F. Sánchez, and W. J. Maciel
Cambridge University Press (CUP)
AbstractWe analyse the evolution with redshift of the radial gradient of oxygen abundances in spiral disks resulting from our MULCHEM chemical evolution models, computed for galaxies of different sizes or masses, studying the relationships between the gradients and galaxy characteristics as the stellar mass, the size, the gas fraction or the star formation rate for z < 4.
L. Sánchez-Menguiano, S. F. Sánchez, I. Pérez, V. P. Debattista, T. Ruiz-Lara, E. Florido, O. Cavichia, L. Galbany, R. A. Marino, D. Mast,et al.
EDP Sciences
Spiral arms are the most singular features in disc galaxies. These structures can exhibit different patterns, namely grand design and flocculent arms, with easily distinguishable characteristics. However, their origin and the mechanisms shaping them are unclear. The overall role of spirals in the chemical evolution of disc galaxies is another unsolved question. In particular, it has not been fully explored if the H ii regions of spiral arms present different properties from those located in the interarm regions. Here we analyse the radial oxygen abundance gradient of the arm and interarm star forming regions of 63 face-on spiral galaxies using CALIFA Integral Field Spectroscopy data. We focus the analysis on three characteristic parameters of the profile: slope, zero-point, and scatter. The sample is morphologically separated into flocculent versus grand design spirals and barred versus unbarred galaxies. We find subtle but statistically significant differences betweenthe arm and interarm distributions for flocculent galaxies, suggesting that the mechanisms generating the spiral structure in these galaxies may be different to those producing grand design systems, for which no significant differences are found. We also find small differences in barred galaxies, not observed in unbarred systems, hinting that bars may affect the chemical distribution of these galaxies but not strongly enough as to be reflected in the overall abundance distribution. In light of these results, we propose bars and flocculent structure as two distinct mechanisms inducing differences in the abundance distribution between arm and interarm star forming regions.
O. Cavichia, R. D. D. Costa, W. J. Maciel, and M. Mollá
Oxford University Press (OUP)
In this work, we report physical parameters and abundances derived for a sample of high extinction planetary nebulae located in the Galactic bulge, near the Galactic Centre, based on low dispersion spectroscopy secured at the SOAR telescope using the Goodman spectrograph. The results show that the abundances of our sample are similar to those from other regions of the bulge. Nevertheless, the average abundances of the Galactic bulge do not follow the observed trend of the radial abundance gradient in the disk. Planetary nebulae (PNe) are the offspring of stars within a large mass interval (0.8−8M⊙). They constitute an important tool to study the chemical evolution of the Milky Way and other galaxies, probing the nucleosynthesis processes, abundance gradients and the chemical enrichment of the interstellar medium (ISM). The fact that PNe are originated from stars of different masses difficults the construction of representatives samples for unbiased chemical composition studies. So that, the presently available chemical composition studies of PNe are strongly biased, since they were focused on brighter objects, predominantly located in Galactic regions of low interstellar reddening. In this work, we report physical parameters and abundances derived for a sample of high extinction PNe located in the Galactic bulge, near the Galactic Centre (GC), based on low dispersion spectroscopy secured at the SOAR telescope using the Goodman spectrograph. The results point to weaker, highly obscured PNe, with E(B-V) roughly 2.3 on the average, that are at the faint end of the PNe luminosity function (PNLF). With such high extinction, no lines are seen in the blue part of the spectra, at wavelengths shorter than Hβ(486.1 nm). From the point of view of the abundances, Fig. 1 (top) shows sulfur as a function of oxygen abundances. Triangles and stars represent the data obtained with SOAR, and filled circles the data from Cavichia et al. (2010), hereafter CCM10. We assumed a temperature of 10000 K for PNe to which we could not
Mercedes Mollá, Ángeles I. Díaz, Brad K. Gibson, Oscar Cavichia, and Ángel-R. López-Sánchez
Oxford University Press (OUP)
Spiral galaxies are thought to acquire their gas through a protracted infall phase resulting in the inside-out growth of their associated discs. For field spirals, this infall occurs in the lower density environments of the cosmic web. The overall infall rate, as well as the galactocentric radius at which this infall is incorporated into the star-forming disc, plays a pivotal role in shaping the characteristics observed today. Indeed, characterising the functional form of this spatio-temporal infall in-situ is exceedingly difficult, and one is forced to constrain these forms using the present day state of galaxies with model or simulation predictions. We present the infall rates used as input to a grid of chemical evolution models spanning the mass spectrum of discs observed today. We provide a systematic comparison with alternate analytical infall schemes in the literature, including a first comparison with cosmological simulations. Identifying the degeneracies associated with the adopted infall rate prescriptions in galaxy models is an important step in the development of a consistent picture of disc galaxy formation and evolution.
Mercedes Mollá, Oscar Cavichia, Roberto D. D. Costa, Walter J. Maciel, Brad Gibson, and Angeles I Díaz
Cambridge University Press (CUP)
AbstractWe review the state of our chemical evolution models for spiral and low mass galaxies. We analyze the consequences of using different stellar yields, infall rate laws and star formation prescriptions in the time/redshift evolution of the radial distributions of abundances, and other quantities as star formation rate or gas densities, in the Milky Way Galaxy; In particular we will study the evolution of the oxygen abundance radial gradient analyzing its relation with the ratio SFR/infall. We also compare the results with our old chemical evolution models, cosmological simulations and with the existing data, mainly with the planetary nebulae abundances.
Mercedes Mollá, Angeles I. Díaz, Brad K. Gibson, Oscar Cavichia, and Ángel-R. López-Sánchez
Cambridge University Press (CUP)
AbstractWe summarize the results obtained from our suite of chemical evolution models for spiral disks, computed for different total masses and star formation efficiencies. Once the gas, stars and star formation radial distributions are reproduced, we analyze the Oxygen abundances radial profiles for gas and stars, in addition to stellar averaged ages and global metallicity. We examine scenarios for the potential origin of the apparent flattening of abundance gradients in the outskirts of disk galaxies, in particular the role of molecular gas formation prescriptions.
L. Sánchez-Menguiano, S. F. Sánchez, I. Pérez, R. García-Benito, B. Husemann, D. Mast, A. Mendoza, T. Ruiz-Lara, Y. Ascasibar, J. Bland-Hawthorn,et al.
EDP Sciences
We measured the gas abundance profiles in a sample of 122 face-on spiral galaxies observed by the CALIFA survey and included all spaxels whose line emission was consistent with star formation. This type of analysis allowed us to improve the statistics with respect to previous studies, and to properly estimate the oxygen distribution across the entire disc to a distance of up to 3-4 disc effective radii (r$_e$). We confirm the results obtained from classical HII region analysis. In addition to the general negative gradient, an outer flattening can be observed in the oxygen abundance radial profile. An inner drop is also found in some cases. There is a common abundance gradient between 0.5 and 2.0 r$_e$ of $\\alpha_{O/H} = -\\,0.075\\,\\rm{dex}/r_e$ with a scatter of $\\sigma = 0.016\\,\\rm{dex}/r_e$ when normalising the distances to the disc effective radius. By performing a set of Kolmogorov-Smirnov tests, we determined that this slope is independent of other galaxy properties, such as morphology, absolute magnitude, and the presence or absence of bars. In particular, barred galaxies do not seem to display shallower gradients, as predicted by numerical simulations. Interestingly, we find that most of the galaxies in the sample with reliable oxygen abundance values beyond $\\sim 2$ effective radii (57 galaxies) present a flattening of the abundance gradient in these outer regions. This flattening is not associated with any morphological feature, which suggests that it is a common property of disc galaxies. Finally, we detect a drop or truncation of the abundance in the inner regions of 27 galaxies in the sample; this is only visible for the most massive galaxies.
Oleksandra V. Ivanova, Igor V. Luk׳yanyk, Nikolay N. Kiselev, Viktor L. Afanasiev, Enos Picazzio, Oscar Cavichia, Amaury A. de Almeida, and Sergei M. Andrievsky
Elsevier BV
S. F. Sánchez, R. García-Benito, S. Zibetti, C. J. Walcher, B. Husemann, M. A. Mendoza, L. Galbany, J. Falcón-Barroso, D. Mast, J. Aceituno,et al.
EDP Sciences
This paper describes the Third Public Data Release (DR3) of the Calar Alto Legacy Integral Field Area (CALIFA) survey. Science-grade quality data for 667 galaxies are made public, including the 200 galaxies of the Second Public Data Release (DR2). Data were obtained with the integral-field spectrograph PMAS/PPak mounted on the 3.5m telescope at the Calar Alto Observatory. Three different spectral setups are available, i) a low-resolution V500 setup covering the wavelength range 3749-7500 AA (4240-7140 AA unvignetted) with a spectral resolution of 6.0 AA (FWHM), for 646 galaxies, ii) a medium-resolution V1200 setup covering the wavelength range 3650-4840 AA (3650-4620 AA unvignetted) with a spectral resolution of 2.3 AA (FWHM), for 484 galaxies, and iii) the combination of the cubes from both setups (called COMBO), with a spectral resolution of 6.0 AA and a wavelength range between 3700-7500 AA (3700-7140 AA unvignetted), for 446 galaxies. The Main Sample, selected and observed according to the CALIFA survey strategy covers a redshift range between 0.005 and 0.03, spans the color-magnitude diagram and probes a wide range of stellar mass, ionization conditions, and morphological types. The Extension Sample covers several types of galaxies that are rare in the overall galaxy population and therefore not numerous or absent in the CALIFA Main Sample. All the cubes in the data release were processed using the latest pipeline, which includes improved versions of the calibration frames and an even further improved im- age reconstruction quality. In total, the third data release contains 1576 datacubes, including ~1.5 million independent spectra. It is available at this http URL
Mercedes Mollá, Oscar Cavichia, Marta Gavilán, and Brad K. Gibson
Oxford University Press (OUP)
We present a set of 144 galactic chemical evolution models applied to a Milky Way analogue, computed using four sets of low+intermediate star nucleosynthetic yields, six massive sta r yield compilations, and six functional forms for the initia l mass function. The integrated or true yields for each combination are derived. A comparison is made between a grid of multiphase chemical evolution models computed with these yield combinations and empirical data drawn from the Milky Way’s disc, including the solar nei ghbourhood. By means of a χ 2 methodology, applied to the results of these multiphase models, the best combination of stellar yields and initial mass function capable of reprodu cing these observations is identified.
O. Cavichia, M. Mollá, R. D. D. Costa, and W. J. Maciel
Oxford University Press (OUP)
In the absence of an interaction, central bars might be the most effective mechanism for radial motions of gas in barred spiral galaxies, which represent two-thirds of disc galaxies. The dynamical effects induced by bars in the first few kpc of discs might play an important role in the disc profiles in this region. In this work, a chemical evolution model with radial gas flows is proposed in order to mimic the effects of the Milky Way bar in the bulge and inner disc. The model is an update of a chemical evolution model with the inclusion of radial gas flows in the disc and bulge. The exchange of gas between the cylindrical concentric regions that form the Galaxy is modelled considering the flows of gas from and to the adjacent cylindrical regions. The most recent data for the bulge metallicity distribution are reproduced by means of a single and longer bulge collapse time-scale (2 Gyr) than other chemical evolution models predict. The model is able to reproduce the peak in the present star formation rate at 4 kpc and the formation of the molecular gas ring. The model with a bar predicts a flattening of the oxygen radial gradient of the disc. Additionally, models with radial gas flows predict a higher star formation rate during the formation of the bulge. This is in agreement with the most recent observations of the star formation rate at the centre of massive barred spiral galaxies.