arXiv subjects

Jorge K. Barrera-Ballesteros

Publications and source records attributed to Jorge K. Barrera-Ballesteros.

29 records · Page 2Linked to original sources

arXiv2020

The AMUSING++ Nearby Galaxy Compilation: I. Full Sample Characterization and Galactic--Scale Outflows Selection

We present here AMUSING\textrm{++}; the largest compilation of nearby galaxies observed with the MUSE integral field spectrograph so far. This collection consists of 635 galaxies from different MUSE projects covering the redshift interval $0.0002<z<0.1$. The sample and its main properties are characterized and described in here. It includes galaxies of almost all morphological types, with a good coverage in the color-magnitude diagram, within the stellar mass range between 10$^8$ to 10$^{12}$M$_\odot$, and with properties resembling those of a diameter-selected sample. The AMUSING++ sample is therefore suitable to study, with unprecendent detail, the properties of nearby galaxies at global and local scales, providing us with more than 50 million individual spectra. We use this compilation to investigate the presence of galactic outflows. We exploit the use of combined emission-line images to explore the shape of the different ionized components and the distribution along classical diagnostic diagrams to disentangle the different ionizing sources across the optical extension of each galaxy. We use the cross correlation function to estimate the level of symmetry of the emission lines as an indication of the presence of shocks and/or active galactic nuclei. We uncovered a total of 54 outflows, comprising $\sim$8\% of the sample. A large number of the discovered outflows correspond to those driven by active galactic nuclei ($\sim$60\%), suggesting some bias in the selection of our sample. No clear evidence was found that outflow host galaxies are highly star-forming, and outflows appear to be found within all galaxies around the star formation sequence.

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arXiv2019

Spatially-resolved Evolution of Galaxies

Projected in the sky, galaxies are spatially-resolved objects. To understand how they formed and evolve it is necessary to study the spatial distribution of their observables. In this review talk, we briefly describe some scaling relations used to understand the physical processes that drive galaxy evolution, in particular for disk-like star-forming galaxies. First, we explore the relations derived using integrated galactic properties, then we introduce the scaling relations at kpc scales derived using the technique called Integral Field Spectroscopy (IFS) for large samples of galaxies in the nearby Universe.The very existence of scaling relations at kpc scales is a strong evidence that any physical scenario that explains the observed global scaling relations must be able to also explain their local counterpart.

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arXiv2019

The EDGE-CALIFA Survey: Using Optical Extinction to Probe the Spatially-Resolved Distribution of Gas in Nearby Galaxies

We present an empirical relation between the cold gas surface density ($Σ_{\rm gas}$) and the optical extinction (${\rm A_V}$) in a sample of 103 galaxies from the Extragalactic Database for Galaxy Evolution (EDGE) survey. This survey provides CARMA interferometric CO observations for 126 galaxies included in the Calar Alto Legacy Integral Field Area (CALIFA) survey. The matched, spatially resolved nature of these data sets allows us to derive the $Σ_{\rm gas}$-${\rm A_V}$ relation on global, radial, and kpc (spaxel) scales. We determine ${\rm A_V}$ from the Balmer decrement (H$α$/H$β$). We find that the best fit for this relation is $Σ_{\rm gas} ({\rm M_\odot pc^{-2}})\sim~26~\times~ {\rm A_V}({\rm mag})$, and that it does not depend on the spatial scale used for the fit. However, the scatter in the fits increases as we probe smaller spatial scales, reflecting the complex relative spatial distributions of stars, gas, and dust. We investigate the $Σ_{\rm gas}$/ ${\rm A_V}$ ratio on radial and spaxel scales as a function of ${\rm EW(Hα)}$. We find that at larger values of ${\rm EW(Hα)}$ (i.e., actively star-forming regions) this ratio tend to converge to the value expected for dust-star mixed geometries ($\sim$ 30 $\mathrm{M_{\odot} \,pc^{-2}\,mag^{-1}}$). On radial scales, we do not find a significant relation between the $Σ_{\rm gas}$/${\rm A_V}$ ratio and the ionized gas metallicity. We contrast our estimates of $Σ_{\rm gas}$ using ${\rm A_V}$ with compilations in the literature of the gas fraction on global and radial scales as well as with well known scaling relations such as the radial star-formation law and the $Σ_{\rm gas}$-$Σ_*$ relation. These tests show that optical extinction is a reliable proxy for estimating $Σ_{\rm gas}$ in the absence of direct sub/millimeter observations of the cold gas.

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arXiv2019

Secondary Infall in the Seyfert's Sextet: A Plausible Way Out of the Short Crossing Time Paradox

We used integral field spectroscopy from CALIFA DR3 and multiwavelength publicly-available data to investigate the star-formation histories of galaxies in the Seyfert's Sextet (SS, HCG 79). The galaxies H79a, H79b, H79c, and H79f have low star-formation rates despite showing strong signs of interaction. By exploring their individual specific star formation histories (sSFH), we identified three earlier episodes of strong star formation common to these four galaxies. We use the last two episodes as markers of the epochs when the galaxies were crossing. We suggest that after the first turn-around, initially gas-rich galaxies crossed for the first time, consuming most of their gas. Hence after the second turn-around most mergers from second crossings would be mixed or dry. The exception would be gas-rich galaxies intruding for the first time. Therefore, we suggest that SS galaxies have survived one crossing during a Hubble time. Strong Balmer absorption lines and the presence of counter-rotating disks provide independent bounds to the second and first crossing, respectively. This scenario provides a plausible way out of the short crossing time paradox.

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arXiv2019

SDSS-IV MaNGA: Spatial Evolution of Star Formation Triggered by Galaxy Interactions

Galaxy interaction is considered a key driver of galaxy evolution and star formation (SF) history. In this paper, we present an empirical picture of the radial extent of interaction-triggered SF along the merger sequence. The samples under study are drawn from the integral field spectroscopy (IFS) survey SDSS-IV MaNGA, including 205 star-forming galaxies in pairs/mergers and ~1350 control galaxies. For each galaxy in pairs, the merger stage is identified according to its morphological signatures: incoming phase, at first pericenter passage, at apocenter, in merging phase, and in final coalescence. The effect of interactions is quantified by the global and spatially resolved SF rate relative to the SF rate of a control sample selected for each individual galaxy ($Δ$logSFR and $Δ$logsSFR(r), respectively). Analysis of the radial $Δ$logsSFR(r) distributions shows that galaxy interactions have no significant impact on the $Δ$logsSFR(r) during the incoming phase. Right after the first pericenter passage, the radial $Δ$logsSFR(r) profile decreases steeply from enhanced to suppressed activity for increasing galactocentric radius. Later on, SF is enhanced on a broad spatial scale out to the maximum radius we explore (~6.7 kpc) and the enhancement is in general centrally peaked. The extended SF enhancement is also observed for systems at their apocenters and in the coalescence phase, suggesting that interaction-triggered SF is not restricted to the central region of a galaxy. Further explorations of a wide range in parameter space of merger configurations (e.g., mass ratio) are required to constrain the whole picture of interaction-triggered SF.

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arXiv2018

Anomalously low metallicity regions in MaNGA star-forming galaxies: Accretion Caught in Action?

We use data from 1222 late-type star-forming galaxies in the SDSS IV MaNGA survey to identify regions in which the gas-phase metallicity is anomalously-low compared to expectations from the tight empirical relation between metallicity and stellar surface mass-density at a given stellar mass. We find anomalously low metallicity (ALM) gas in 10% of the star-forming spaxels, and in 25% of the galaxies in the sample. The incidence rate of ALM gas increases strongly with both global and local measures of the specific star-formation rate, and is higher in lower mass galaxies and in the outer regions of galaxies. The incidence rate is also significantly higher in morphologically disturbed galaxies. We estimate that the lifetimes of the ALM regions are a few hundred Myr. We argue that the ALM gas has been delivered to its present location by a combination of interactions, mergers, and accretion from the halo, and that this infusion of gas stimulates star-formation. Given the estimated lifetime and duty cycle of such events, we estimate that the time-averaged accretion rate of ALM gas is similar to the star-formation rate in late type galaxies over the mass-range M$_* \sim10^9$ to 10$^{10}$ M$_{\odot}$.

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arXiv2018

Systematic study of outflows in the Local Universe using CALIFA: I. Sample selection and main properties

We present a sample of 17 objects from the CALIFA survey where we find initial evidence of galactic winds based on their off-axis ionization properties. We identify the presence of outflows using various optical diagnostic diagrams (e.g., EW(H$α$), [Nii]/H$α$, [Sii]/H$α$, [Oi]/H$α$ line-ratio maps). We find that all 17 candidate outflow galaxies lie along the sequence of active star formation in the M$_\star$ vs. star-formation rate diagram, without a clear excess in the integrated SFR. The location of galaxies along the star-formation main sequence (SFMS) does not influence strongly the presence or not of outflows. The analysis of the star-formation rate density ($Σ_{\rm SFR}$) reveals that the CALIFA sources present higher values when compared with normal star-forming galaxies. The strength of this relation depends on the calibrator used to estimate the SFR. This excess in $Σ_{\rm SFR}$ is significant within the first effective radius supporting the idea that most outflows are driven by processes in the inner regions of a galaxy. We find that the molecular gas mass density ($Σ_\mathrm{gas}$) is a key parameter that plays an important role in the generation of outflows through its association with the local SFR. The canonical threshold reported for the generation of outflows -- $Σ_{\rm SFR}>0.1$ $\mathrm{M}_\odot \mathrm{yr}^{-1} \mathrm{kpc}^{-2}$ -- is only marginally exceeded in our sample. Within the Kennicutt-Schmidt diagram we propose a domain for galaxies hosting starburst-driven outflows defined by $Σ_{\rm SFR}>10^{-2} \,\mathrm{M}_\odot \mathrm{yr}^{-1} \mathrm{kpc}^{-2}$ and $Σ_\mathrm{gas}>10^{1.2} \, \mathrm{M}_\odot \mathrm{pc}^{-2}$ within a central kiloparcec region.

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arXiv2018

The EDGE-CALIFA Survey: Molecular and Ionized Gas Kinematics in Nearby Galaxies

We present a comparative study of molecular and ionized gas kinematics in nearby galaxies. These results are based on observations from the EDGE survey, which measured spatially resolved $^{12}$CO(J=1-0) in 126 nearby galaxies. Every galaxy in EDGE has corresponding resolved ionized gas measurements from CALIFA. Using a sub-sample of 17 rotation dominated, star-forming galaxies where precise molecular gas rotation curves could be extracted, we derive CO and H$α$ rotation curves using the same geometric parameters out to $\gtrsim$1 $R_e$. We find that $\sim$75% of our sample galaxies have smaller ionized gas rotation velocities than the molecular gas in the outer part of the rotation curve. In no case is the molecular gas rotation velocity measurably lower than that of the ionized gas. We suggest that the lower ionized gas rotation velocity can be attributed to a significant contribution from extraplanar diffuse ionized gas in a thick, turbulence supported disk. Using observations of the H$γ$ transition also available from CALIFA, we measure ionized gas velocity dispersions and find that these galaxies have sufficiently large velocity dispersions to support a thick ionized gas disk. Kinematic simulations show that a thick disk with a vertical rotation velocity gradient can reproduce the observed differences between the CO and H$α$ rotation velocities. Observed line ratios tracing diffuse ionized gas are elevated compared to typical values in the midplane of the Milky Way. In galaxies affected by this phenomenon, dynamical masses measured using ionized gas rotation curves will be systematically underestimated.

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arXiv2017

A Local Leaky-box Model for the Local Stellar Surface Density - Gas Surface Density - Gas Phase Metallicity Relation

We revisit the relation between the stellar surface density, the gas surface density, and the gas-phase metallicity of typical disk galaxies in the local Universe with the SDSS-IV/MaNGA survey, using the star formation rate surface density as an indicator for the gas surface density. We show that these three local parameters form a tight relationship, confirming previous works (e.g., by the PINGS and CALIFA surveys), but with a larger sample. We present a new local leaky-box model, assuming star formation history and chemical evolution is localized except for outflowing materials. We derive closed-form solutions for the evolution of stellar surface density, gas surface density and gas-phase metallicity, and show that these parameters form a tight relation independent of initial gas density and time. We show that, with canonical values of model parameters, this predicted relation match the observed one well. In addition, we briefly describe a pathway to improving the current semi-analytic models of galaxy formation by incorporating the local leaky-box model in the cosmological context, which can potentially explain simultaneously multiple properties of Milky Way-type disk galaxies, such as the size growth and the global stellar mass-gas metallicity relation.

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arXiv2017

Zooming into local active galactic nuclei: The power of combining SDSS-IV MaNGA with higher resolution integral field unit observations

Ionised gas outflows driven by active galactic nuclei (AGN) are ubiquitous in high luminosity AGN with outflow speeds apparently correlated with the total bolometric luminosity of the AGN. This empirical relation and theoretical work suggest that in the range L_bol ~ 10^43-45 erg/s there must exist a threshold luminosity above which the AGN becomes powerful enough to launch winds that will be able to escape the galaxy potential. In this paper, we present pilot observations of two AGN in this transitional range that were taken with the Gemini North Multi-Object Spectrograph Integral Field Unit (IFU). Both sources have also previously been observed within the Sloan Digital Sky Survey-IV (SDSS) Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey. While the MaNGA IFU maps probe the gas fields on galaxy-wide scales and show that some regions are dominated by AGN ionization, the new Gemini IFU data zoom into the centre with four times better spatial resolution. In the object with the lower L_bol we find evidence of a young or stalled biconical AGN-driven outflow where none was obvious at the MaNGA resolution. In the object with the higher L_bol we trace the large-scale biconical outflow into the nuclear region and connect the outflow from small to large scales. These observations suggest that AGN luminosity and galaxy potential are crucial in shaping wind launching and propagation in low-luminosity AGN. The transition from small and young outflows to galaxy-wide feedback can only be understood by combining large-scale IFU data that trace the galaxy velocity field with higher resolution, small scale IFU maps.

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arXiv2016

Do galaxy global relationships emerge from local ones? The SDSS IV MaNGA surface mass density-metallicity relation

We present the stellar surface mass density {\it vs.} gas metallicity ($Σ_*-Z$) relation for more than 500,000 spatially-resolved star-forming resolution elements (spaxels) from a sample of 653 disk galaxies included in the SDSS IV MaNGA survey. We find a tight relation between these local properties, with higher metallicities as the surface density increases. This relation extends over three orders of magnitude in the surface mass density and a factor of four in metallicity. We show that this local relationship can simultaneously reproduce two well-known properties of disk galaxies: their global mass-metallicity relationship {\it and} their radial metallicity gradients. We also find that the $Σ_* - Z$ relation is largely independent of the galaxy's total stellar mass and specific star-formation rate (sSFR), except at low stellar mass and high sSFR. These results suggest that in the present-day universe local properties play a key role in determining the gas-phase metallicity in typical disk galaxies.

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