arXiv subjects

María Sánchez-García

Publications and source records attributed to María Sánchez-García.

3 recordsLinked to original sources

arXiv2026

Multiphase Analysis of (U)LIRG Nuclear Activity (MAUNA). I. Spatially Resolved Optical Emission-Line Diagnostics

We present resolved optical integral-field spectroscopy of the 32 luminous and ultraluminous infrared galaxy systems of the Multiphase Analysis of (U)LIRG Nuclear Activity (MAUNA) sample, drawn from the GOALS survey and selected to have JWST/MIRI medium-resolution spectrometer (MRS) observations. The data set combines new Keck/KCWI observations of 10 systems with archival VLT/MUSE cubes for 22 systems, covering H$β$ to [S II] at ~1 arcsecond spatial resolution (~0.9 kpc at the sample median distance). Using the optical [N II]/H$α$ BPT diagram, we find that composite and LINER-like excitation together account for most of the classified area (median fractions 0.44 and 0.26), while Seyfert-like gas covers a median fraction of 0.02 but carries a far larger proportion of the line luminosity where it is present. Both the projected size of the Seyfert-classified region, $R_{\rm Sy}=0.08$-$7.5$ kpc, and its [O III] luminosity increase with the bolometric AGN luminosity, with $R_{\rm Sy}\propto L_{\rm AGN,bol}^{0.54\pm0.18}$, as expected for gas photoionized at a constant ionization parameter. The scatter about the luminosity relation depends on dust opacity: the [O III] luminosity per unit AGN luminosity falls by $1.09\pm0.25$ dex per unit depth of the 9.7 $μ$m silicate absorption feature (Spearman $ρ=-0.60$, $p=0.001$). Optical excitation diagnostics therefore locate AGN-excited gas reliably but systematically underestimate the luminosity the AGN supplies to the host in the most obscured (U)LIRGs.

astro-ph.GA↗

arXiv2024

The Arp 240 Galaxy Merger: A Detailed Look at the Molecular Kennicutt-Schmidt Star Formation Law on Sub-kpc Scales

The molecular Kennicutt-Schmidt (mK-S) Law has been key for understanding star formation (SF) in galaxies across all redshifts. However, recent sub-kpc observations of nearby galaxies reveal deviations from the nearly unity slope (N) obtained with disk-averaged measurements. We study SF and molecular gas (MG) distribution in the early-stage luminous infrared galaxy merger Arp240 (NGC5257-8). Using VLA radio continuum (RC) and ALMA CO(2-1) observations with a uniform grid analysis, we estimate SF rates and MG surface densities ($Σ_{\mathrm{SFR}}$ and $Σ_{\mathrm{H_2}}$, respectively). In Arp 240, N is sub-linear at 0.52 $\pm$ 0.17. For NGC 5257 and NGC 5258, N is 0.52 $\pm$ 0.16 and 0.75 $\pm$ 0.15, respectively. We identify two SF regimes: high surface brightness (HSB) regions in RC with N $\sim$1, and low surface brightness (LSB) regions with shallow N (ranging 0.15 $\pm$ 0.09 to 0.48 $\pm$ 0.04). Median CO(2-1) linewidth and MG turbulent pressure (P$_{\mathrm{turb}}$) are 25 km s$^{-1}$ and 9 $\times$10$^{5}$ K cm$^{-3}$. No significant correlation was found between $Σ_{\mathrm{SFR}}$ and CO(2-1) linewidth. However, $Σ_{\mathrm{SFR}}$ correlates with P$_{\mathrm{turb}}$, particularly in HSB regions ($ρ>$0.60). In contrast, SF efficiency moderately anti-correlates with P$_{\mathrm{turb}}$ in LSB regions but shows no correlation in HSB regions. Additionally, we identify regions where peaks in SF and MG are decoupled, yielding a shallow N ($\leq$ 0.28 $\pm$ 0.18). Overall, the range of N reflects distinct physical properties and distribution of both the SF and MG, which can be masked by disk-averaged measurements.

astro-ph.GA↗

arXiv2021

Vibrationally excited HC3N emission in NGC1068: Tracing the recent star formation in the starburst ring

Using ALMA data, we have studied the HC$_3$N and continuum emission in the starburst ring (SB ring) and the circumnuclear disc (CND) of the SB/AGN composite galaxy NGC 1068. We have detected emission from vibrationally excited HC$_3$N (HC$_3$N*) only towards one star-forming region of the SB ring. Remarkably, HC$_3$N* was not detected towards the CND despite its large HC$_3$N $v=0$ column density. From LTE and non-LTE modelling of HC$_3$N*, we obtained a dust temperature of $ T_\text{dust} \sim 250$ K and a density of $n_{\text{H}_2}=6\times10^5$ cm$^{-3}$ for this star-forming region. The estimated IR luminosity of $5.8\times10^8$ L$_\odot$ is typical of proto-Super Star Clusters (proto-SSC) observed in the SB galaxy NGC 253. We use the continuum emissions at $147$ GHz and $350$ GHz, along with CO and Pa $α$, to estimate the ages of other $14$ SSCs in the SB ring. We find the youngest SSCs to be associated with the region connecting the nuclear bar with the SB ring, supporting the scenario of sequential star formation. For the CND, our analysis yields $T_\text{dust} \leqslant 100$ K and $n_{\text{H}_2}\sim(3-6)\times10^5$cm$^{-3}$. The very different dust temperatures found for the CND and the proto-SSC indicates that, while the dust in the proto-SSC is being efficiently heated from the inside by the radiation from massive proto-stars, the CND is being heated externally by the AGN, which in the IR optically thin case can only heat the dust to $56$ K. We discuss the implications of the non-detection of HC$_3$N* near the luminous AGN in NGC 1068 on the interpretation of the HC$_3$N* emission observed in the SB/AGN composite galaxies NGC 4418 and Arp 220.

astro-ph.GA↗