arXiv subjects

A. B. Romeo

Publications and source records attributed to A. B. Romeo.

3 recordsLinked to original sources

arXiv2025

Resolving the molecular gas emission of the z~2.5-2.8 starburst galaxies SPT0125-47 and SPT 2134-50

The comoving cosmic star formation rate density peaks at z~2-3, with dusty star-forming galaxies being significant contributors to this peak. These galaxies are characterized by their high star formation rates and substantial infrared luminosities. The formation mechanisms remain an open question for these galaxies, particularly with respect to how such intense levels of star formation are triggered and maintained. We aim to resolve CO(3-2) emission toward two strongly lensed galaxies, SPT0125-47 and SPT2134-50, at z~2.5-2.8 to determine their morphology and physical properties. We used high-resolution ALMA band 3 observations of CO(3-2) emission toward both sources to investigate their properties. We performed parametric and nonparametric lens modeling using the publicly available lens modeling software PyAutoLens. We divided the CO(3-2) emission line into two bins corresponding to the red and blue portions of the emission line and nonparametrically modeled the source plane emission for both bins. We performed a basic analysis of the morphology and kinematics in the source plane using nonparametric lens modeling of the red and blue bins. We found tentative evidence of a velocity gradient across both sources and no evidence of any clumpy structure, companions, or ongoing mergers. The previously calculated high star formation rates and low depletion times of both SPT0125-47 and SPT2134-50 suggest that these galaxies are undergoing a dramatic phase in their evolution. Given the lack of evidence of ongoing interactions or mergers in our source plane models, we suggest that the intense star formation was triggered by a recent interaction and/or merger. We also consider the possibility that these galaxies might be in the process of settling into disks.

astro-ph.GA↗

arXiv2022

Investigating the link between inner gravitational potential and star-formation quenching in CALIFA galaxies

It has been suggested that the gravitational potential can have a significant role in suppressing the star formation in the nearby galaxies. To establish observational constrains on this scenario, we investigate the connection between the dynamics, through the circular velocity curves (CVCs) as a proxy of the inner gravitational potential, and star formation quenching in 215 non-active galaxies across Hubble sequence from the Calar Alto Legacy Integral Field Area (CALIFA) survey. Our results show that galaxies with similar CVCs tend to have a certain star-formation quenching pattern. To explore these findings in more details, we construct kpc-resolved relations of the equivalent width of the H$α$ ($W_{{\rm H}α}$) versus the amplitude ($V_c$) and shape ($β= d\ln V_c/ d\ln R$) of the circular velocity at given radius. We find that the $W_{{\rm H}α}-V_c$ is a declining relationship, where the retired regions of the galaxies (the ones with $W_{{\rm H}α}$ values below 3 Å) tend to have higher $V_c$. Differently, $W_{{\rm H}α}-β$ is a bi-modal relationship, characterised by two peaks: concentration of the star forming regions at a positive $β$ (rising CVC) and another one of the retired regions with a negative $β$ (declining CVC). Our results show that both the amplitude of the CVC, driven by the mass of the galaxies, and the shape of the CVC, reflecting the internal structure of the galaxies, play an important role in galaxy's quenching history.

astro-ph.GA↗

arXiv2001

Properties of galaxy halos in Clusters and Voids

We use the results of a high resolution N-body simulation to investigate the role of the environment on the formation and evolution of galaxy-sized halos. Starting from a set of constrained initial conditions, we have produced a final configuration hosting a double cluster in one octant and a large void extending over two octants of the simulation box. We present results for two statistics: the relationship between 1-D velocity dispersion and mass and the probability distribution of the spin parameter $P(λ)$. The \svm relationship is well reproduced by the Truncated Isothermal Sphere (TIS) model introduced by Shapiro et al. (1999), although the slope is different from the original prediction. A series of \svm relationships for different values of the anisotropy parameter $β$, obtained using the theoretical predictions by Lokas and Mamon (2001) for NFW density profiles are found to be only marginally consistent with the data. Using some properties of the equilibrium TIS models, we construct subsamples of {\em fiducial} equilibrium TIS halos from each of the three subregions, and we study their properties. For these halos, we do find an environmental dependence of their properties, in particular of the spin parameter distribution $P(λ)$. We study in more detail the TIS model, and we find new relationships between the truncation radius and other structural parameters. No gravitationally bound halo is found having a radius larger than the critical value for gravithermal instability for TIS halos (\rt $\ge 34.2 r_{0}$, where $r_{0}$ is the core radius of the TIS solution). We do however find a dependence of this relationship on the environment, like for the $P(λ)$ statistics. These facts hint at a possible rôle of tidal fields at determining the statistical properties of halos.

astro-ph↗