arXiv subjects

Carla M. Canelo

Publications and source records attributed to Carla M. Canelo.

4 recordsLinked to original sources

arXiv2026

Variations in the 6.2 $μ$m polycyclic aromatic hydrocarbon band in Active Galactic Nuclei- and Starburst-dominated galaxies

Polycyclic aromatic hydrocarbons (PAHs) are fundamental to understanding the interstellar medium (ISM) of several astrophysical objects. Normally present in Starburst (SB) galaxies, they have also been more frequently detected in active galaxy nuclei (AGNs), suggesting an inner dusty torus that can shield the radiation from the central black role. In this work, we analyze the 6.2 $μ$m PAH band of SB-, AGN- and mixed-dominated spectra from 175 IDEOS database galaxies. After fitting of the band, the sources were distributed into the Peeters' A, B and C classes according to their profile peak positions. Class A objects are predominant in 80% of the entire sample, which could indicate the presence of PAHs with nitrogen incorporation. The water ice absorption at 6.0 $μ$m was also studied in eleven objects, and it affected the PAH band poorly. A prominent second spectral feature after 6.3 $μ$m is present in ten galaxies. Fitting both PAH profiles at 6.2 $μ$m changes all the fit results: the first profile is consistently blue-shifted and classified as class A due to the presence of the second component. Further studies are needed to better comprehend these PAH trends in galactic environments.

astro-ph.GA↗

arXiv2021

Profile comparison of the 6-9 $μ$m polycyclic aromatic hydrocarbon bands in starburst-dominated galaxies

Polycyclic aromatic hydrocarbons (PAHs) are of great astrochemical and astrobiological interest due to their potential to form prebiotic molecules. We analyse the 7.7 and 8.6 $μ$m PAH bands in 126 predominantly starburst-dominated galaxies extracted from the Spitzer/IRS ATLAS project. Based on the peak positions of these bands, we classify them into the different A, B, and C Peeters' classes, which allows us to address the potential characteristics of the PAH emitting population. We compare this analysis with previous work focused on the 6.2 $μ$m PAH band for the same sample. For the first time in the literature, this statistical analysis is performed on a sample of galaxies. In our sample, the 7.7 $μ$m complex is equally distributed in A and B object's class while the 8.6 $μ$m band presents more B class sources. Moreover, 39 per cent of the galaxies were distributed into A class objects for both 6.2 and 7.7 $μ$m bands and only 18 per cent received the same A classification for the three bands. The "A A A" galaxies presented higher temperatures and less dust in their interstellar medium. Considering the redshift range covered by our sample, the distribution of the three bands into the different Peeters' classes reveals a potential cosmological evolution in the molecular nature of the PAHs that dominate the interstellar medium in these galaxies, where B class objects seem to be more frequent at higher redshifts and, therefore, further studies have to be addressed.

astro-ph.GA↗

arXiv2021

Isocyanic acid (HNCO) in the Hot Molecular Core G331.512-0.103: Observations and Chemical Modelling

Isocyanic acid (HNCO) is a simple molecule with a potential to form prebiotic and complex organic species. Using a spectral survey collected with the Atacama Pathfinder EXperiment (APEX), in this work we report the detection of 42 transitions of HNCO in the hot molecular core/outflow G331.512-0.103 (hereafter G331). The spectral lines were observed in the frequency interval $\sim$ 160 - 355 GHz. By means of Local Thermodynamic Equilibrium (LTE) analyses, applying the rotational diagram method, we studied the excitation conditions of HNCO. The excitation temperature and column density are estimated to be $T_{ex}$ = 58.8 $\pm$ 2.7 K and $N$ = (3.7 $\pm$ 0.5) $\times$ 10$^{15}$ cm$^{-2}$, considering beam dilution effects. The derived relative abundance is between (3.8 $\pm$ 0.5) $\times $10$^{-9}$ and (1.4 $\pm$ 0.2) $\times $10$^{-8}$. In comparison with other hot molecular cores, our column densities and abundances are in agreement. An update of the internal partition functions of the four CHNO isomers: HNCO; cyanic acid, HOCN; fulminic acid, HCNO; and isofulminic acid, HONC is provided. We also used the astrochemical code Nautilus to model and discuss HNCO abundances. The simulations could reproduce the abundances with a simple zero-dimensional model at a temperature of 60 K and for a chemical age of $\sim$ 10$^5$ years, which is larger than the estimated dynamical age for G331. This result could suggest the need for a more robust model and even the revision of chemical reactions associated with HNCO.

astro-ph.GA↗

arXiv2019

Sulphur-Bearing and Complex Organic Molecules in an Infrared Cold Core

Since the start of ALMA observatory operation, new and important chemistry of infrared cold core was revealed. Molecular transitions at millimeter range are being used to identify and to characterize these sources. We have investigated the 231 GHz ALMA archive observations of the infrared dark cloud region C9, focusing on the brighter source that we called as IRDC-C9 Main. We report the existence of two sub-structures on the continuum map of this source: a compact bright spot with high chemistry diversity that we labelled as core, and a weaker and extended one, that we labelled as tail. In the core, we have identified lines of the molecules OCS(19-18), $^{13}$CS(5-4) and CH$_{3}$CH$_{2}$CN, several lines of CH$_{3}$CHO and the k-ladder emission of $^{13}$CH$_{3}$CN.We report two different temperature regions: while the rotation diagram of CH$_{3}$CHO indicates a temperature of 25 K, the rotation diagram of $^{13}$CH$_{3}$CN indicates a warmer phase at temperature of $\sim450$K. In the tail, only the OCS(19-18) and $^{13}$CS(5-4) lines were detected. We used the $Nautilus$ and the \textsc{Radex} codes to estimate the column densities and the abundances. The existence of hot gas in the core of IRDC-C9 Main suggests the presence of a protostar, which is not present in the tail.

astro-ph.SR↗