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Luis Colina

Publications and source records attributed to Luis Colina.

At least 55 records · Page 3Linked to original sources
arXiv2024

Extended high-ionization [MgIV] emission tracing widespread shocks in starbursts seen by JWST /NIRSpec

We report the detection of extended (>0.5-1kpc) high-ionization [MgIV] 4.487 $μ$m (80 eV) emission in four local luminous infrared galaxies observed with JWST/NIRSpec. Excluding the nucleus and outflow of the Type 1 active galactic nucleus (AGN) in the sample, we find that the [MgIV] luminosity is well correlated with that of H recombination lines, which mainly trace star forming clumps in these objects, and that the [ArVI] 4.530 $μ$m (75 eV), usually seen in AGN, is undetected. On 100-400pc scales, the [MgIV] line profiles are broader (sigma([MgIV])=90 +- 25 km/s) and shifted (Delta_v up to +- 50 km/s) compared to those of the H recombination lines and lower ionization transitions (e.g., sigma(Hu-12)=57 +- 15 km/s). The [MgIV] kinematics follow the large scale rotating velocity field of these galaxies and the broad [MgIV] profiles are compatible with the broad wings detected in the H recombination lines. Based on these observational results, extended highly ionized gas more turbulent than the ambient interstellar medium, possibly as a result of ionizing shocks associated with star-formation, is the most likely origin of the [MgIV] emission. We also computed new grids of photoionization and shock models to investigate where the [MgIV] line originates. Shocks with velocities of 100-130 km/s reproduce the observed line ratios and the [MgIV] luminosity agrees with that expected from the mechanical energy released by supernove (SNe) in these regions. Therefore, these models support shocks induced by SNe as the origin of the [MgIV] line. Future studies on the stellar feedback from SNe will benefit from the [MgIV] line that is little affected by obscuration and, in absence of an AGN, can only be produced by shocks due to its high ionization potential.

astro-ph.GA↗
arXiv2024

MINDS. The DR Tau disk I: combining JWST-MIRI data with high-resolution CO spectra to characterise the hot gas

The MRS mode of the JWST-MIRI instrument has been shown to be a powerful tool to characterise the molecular gas emission of the inner region of planet-forming disks. Here, we analyse the spectrum of the compact T-Tauri disk DR Tau, which is complemented by high spectral resolution (R~60000-90000) CO ro-vibrational observations. Various molecular species, including CO, CO$_2$, HCN, and C$_2$H$_2$ are detected in the JWST-MIRI spectrum, for which excitation temperatures of T~325-900 K are retrieved using LTE slab models. The high-resolution CO observations allow for a full treatment of the line profiles, which show evidence for two components of the main isotopologue, $^{12}$CO: a broad component tracing the Keplerian disk and a narrow component tracing a slow disk wind. Rotational diagrams yield excitation temperatures of T>725 K for CO, with consistently lower temperatures found for the narrow components, suggesting that the disk wind is launched from a larger distance. The inferred excitation temperatures for all molecules suggest that CO originates from the highest atmospheric layers close to the host star, followed by HCN and C$_2$H$_2$, which emit, together with $^{13}$CO, from slightly deeper layers, whereas the CO$_2$ originates from even deeper inside or further out in the disk. Additional analysis of the $^{12}$CO line wings hint at a misalignment between the inner (i~20 degrees) and outer disk (i~5 degrees). Finally, we emphasise the need for complementary high-resolution CO observations, as in combination with the JWST-MIRI observations they can be used to characterise the CO kinematics and the physical and chemical conditions of the other observed molecules with respect to CO.

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arXiv2024

MINDS: The JWST MIRI Mid-INfrared Disk Survey

The study of protoplanetary disks has become increasingly important with the Kepler satellite finding that exoplanets are ubiquitous around stars in our galaxy and the discovery of enormous diversity in planetary system architectures and planet properties. High-resolution near-IR and ALMA images show strong evidence for ongoing planet formation in young disks. The JWST MIRI mid-INfrared Disk Survey (MINDS) aims to (1) investigate the chemical inventory in the terrestrial planet-forming zone across stellar spectral type, (2) follow the gas evolution into the disk dispersal stage, and (3) study the structure of protoplanetary and debris disks in the thermal mid-IR. The MINDS survey will thus build a bridge between the chemical inventory of disks and the properties of exoplanets. The survey comprises 52 targets (Herbig Ae stars, T Tauri stars, very low-mass stars and young debris disks). We primarily obtain MIRI/MRS spectra with high S/N (~100-500) covering the complete wavelength range from 4.9 to 27.9 μm. For a handful of selected targets we also obtain NIRSpec IFU high resolution spectroscopy (2.87-5.27 μm). We will search for signposts of planet formation in thermal emission of micron-sized dust - information complementary to near-IR scattered light emission from small dust grains and emission from large dust in the submillimeter wavelength domain. We will also study the spatial structure of disks in three key systems that have shown signposts for planet formation, TW Hya and HD 169142 using the MIRI coronagraph at 15.5 μm and 10.65 μm respectively and PDS70 using NIRCam imaging in the 1.87 μm narrow and the 4.8 μm medium band filter. ...

astro-ph.EP↗
arXiv2024

MIDIS: JWST NIRCam and MIRI unveil the stellar population properties of Ly$α$-emitters and Lyman-Break galaxies at z ~ 3-7

We study the stellar population properties of 182 spectroscopically-confirmed (MUSE/VLT) Lyman-$α$ emitters (LAEs) and 450 photometrically-selected Lyman-Break galaxies (LBGs) at z = 2.8 - 6.7 in the Hubble eXtreme Deep Field (XDF). Leveraging the combined power of HST and JWST NIRCam and MIRI observations, we analyse their rest-frame UV-through-near-IR spectral energy distributions (SEDs) with MIRI playing a crucial role in robustly assessing the LAE's stellar mass and ages. Our LAEs are low-mass objects (log$_{10}$(M$_\star$[M$_\odot$]) ~ 7.5), with little or no dust extinction (E(B - V) ~ 0.1) and a blue UV continuum slope ($β$ ~ -2.2). While 75% of our LAEs are young (< 100 Myr), the remaining 25% have significantly older stellar populations (> 100 Myr). These old LAEs are statistically more massive, less extinct and have lower specific star formation rate (sSFR) compared to young LAEs. Besides, they populate the M$_\star$ - SFR plane along the main-sequence (MS) of star-forming galaxies, while young LAEs populate the starburst region. The comparison between the LAEs properties to those of a stellar-mass matched sample of LBGs shows no statistical difference between these objects, except for the LBGs redder UV continuum slope and marginally larger E(B - V) values. Interestingly, 48% of the LBGs have ages < 10 Myr and are classified as starbursts, but lack detectable Ly$α$ emission. This is likely due to HI resonant scattering and/or selective dust extinction. Overall, we find that JWST observations are crucial in determining the properties of LAEs and shedding light on the properties and similarities between LAEs and LBGs.

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arXiv2023

15NH3 in the atmosphere of a cool brown dwarf

Brown dwarfs serve as ideal laboratories for studying the atmospheres of giant exoplanets on wide orbits as the governing physical and chemical processes in them are nearly identical. Understanding the formation of gas giant planets is challenging, often involving the endeavour to link atmospheric abundance ratios, such as the carbon-to-oxygen (C/O) ratio, to formation scenarios. However, the complexity of planet formation requires additional tracers, as the unambiguous interpretation of the measured C/O ratio is fraught with complexity. Isotope ratios, such as deuterium-to-hydrogen and 14N/15N, offer a promising avenue to gain further insight into this formation process, mirroring their utility within the solar system. For exoplanets only a handful of constraints on 12C/13C exist, pointing to the accretion of 13C-rich ice from beyond the disks' CO iceline. Here we report on the mid-infrared detection of the 14NH3 and 15NH3 isotopologues in the atmosphere of a cool brown dwarf with an effective temperature of 380 K in a spectrum taken with the Mid-InfraRed Instrument of the James Webb Space Telescope. As expected, our results reveal a 14N/15N value consistent with star-like formation by gravitational collapse, demonstrating that this ratio can be accurately constrained. Since young stars and their planets should be more strongly enriched in the 15N isotope, we expect that 15NH3 will be detectable in a number of cold, wide-separation exoplanets.

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arXiv2023

MINDS. Abundant water and varying C/O across the disk of Sz 98 as seen by JWST/MIRI

MIRI/MRS on board the JWST allows us to probe the inner regions of protoplanetary disks. Here we examine the disk around the classical T Tauri star Sz 98, which has an unusually large dust disk in the millimetre with a compact core. We focus on the H$_2$O emission through both its ro-vibrational and pure rotational emission. Furthermore, we compare our chemical findings with those obtained for the outer disk from Atacama Large Millimeter/submillimeter Array (ALMA) observations. In order to model the molecular features in the spectrum, the continuum was subtracted and LTE slab models were fitted. The spectrum was divided into different wavelength regions corresponding to H$_2$O lines of different excitation conditions, and the slab model fits were performed individually per region. We confidently detect CO, H$_2$O, OH, CO$_2$, and HCN in the emitting layers. The isotopologue H$^{18}_2$O is not detected. Additionally, no other organics, including C$_2$H$_2$, are detected. This indicates that the C/O ratio could be substantially below unity, in contrast with the outer disk. The H$_2$O emission traces a large radial disk surface region, as evidenced by the gradually changing excitation temperatures and emitting radii. The OH and CO$_2$ emission are relatively weak. It is likely that H$_2$O is not significantly photodissociated; either due to self-shielding against the stellar irradiation, or UV-shielding from small dust particles. The relative emitting strength of the different identified molecular features point towards UV-shielding of H$_2$O in the inner disk of Sz 98, with a thin layer of OH on top. The majority of the organic molecules are either hidden below the dust continuum, or not present. In general, the inferred composition points to a sub-solar C/O ratio (<0.5) in the inner disk, in contrast with the larger than unity C/O ratio in the gas in the outer disk found with ALMA.

astro-ph.EP↗
arXiv2023

Reionization and the ISM/Stellar Origins with JWST and ALMA (RIOJA): The core of the highest redshift galaxy overdensity at $z = 7.88$ confirmed by NIRSpec/JWST

The protoclusters in the epoch of reionization, traced by galaxies overdensity regions, are ideal laboratories for studying the process of stellar assembly and cosmic reionization. We present the spectroscopic confirmation of the core of the most distant protocluster at $z = 7.88$, A2744-z7p9OD, with the James Webb Space Telescope NIRSpec integral field unit spectroscopy. The core region includes as many as 4 galaxies detected in [OIII] 4960 Å and 5008 Å in a small area of $\sim 3\arcsec \times 3\arcsec$, corresponding to $\sim$ 11 kpc $\times$ 11 kpc, after the lensing magnification correction. Three member galaxies are also tentatively detected in dust continuum in Atacama Large Millimeter/submillimeter Array Band 6, which is consistent with their red ultraviolet continuum slopes, $β\sim -1.3$. The member galaxies have stellar masses in the range of log($M_{*}/M_{\rm \odot}$) $\sim 7.6-9.2$ and star formation rates of $\sim 3-50$ $M_{\rm \odot}$ yr$^{-1}$, showing a diversity in their properties. FirstLight cosmological simulations reproduce the physical properties of the member galaxies including the stellar mass, [OIII] luminosity, and dust-to-stellar mass ratio, and predict that the member galaxies are on the verge of merging in a few to several tens Myr to become a large galaxy with $M_{\rm *}\sim 6\times10^{9} M_{\rm \odot}$. The presence of a multiple merger and evolved galaxies in the core region of A2744-z7p9OD indicates that environmental effects are already at work 650 Myr after the Big Bang.

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arXiv2023

First rest-frame infrared spectrum of a z>7 quasar: JWST/MRS observations of J1120+0641

We present a JWST/MRS spectrum of the quasar J1120+0641 at z=7.0848, the first spectroscopic observation of a reionisation-era quasar in the rest-frame infrared ($0.6<λ<3.4μ$m). In the context of the mysterious fast assembly of the first supermassive black holes at z>7, our observations enable for the first time the detection of hot torus dust, the H$α$ emission line, and the Paschen-series broad emission lines in a quasar at z>7. Hot torus dust is clearly detected as an upturn in the continuum emission at $λ_{\text{rest}}\simeq1.3μ$m, leading to a black-body temperature of $T=1413.5^{+5.7}_{-7.4}$K. Compared to similarly-luminous quasars at 0 6 ($2σ$ significance). We measure the black hole mass of J1120+0641 based on the H$α$ Balmer line, $M_{\text{BH}}=1.52\pm0.17\cdot 10^9 M_\odot$, which is in good agreement with the previous rest-UV MgII black hole mass measurement. The black hole mass based on the Paschen-series lines is also consistent, indicating no significant extinction in the rest-frame UV measurement. The broad H$α$, Pa-$α$ and Pa-$β$ emission lines are consistent with an origin in a common broad-line region (BLR) with density log$N_H/\text{cm}^{-3}\geq 12$, ionisation parameter $-7<$log$U<-4$, and extinction E(B-V)$\lesssim 0.1$mag. These BLR parameters are consistent with similarly-bright quasars at 0<z<4. Overall, we find that both J1120+0641's hot dust torus and hydrogen BLR properties show no significant peculiarity when compared to luminous quasars down to z=0. The quasar accretion structures must have therefore assembled very quickly, as they appear fully "mature" less than 760 million years after the Big Bang.

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arXiv2023

Life beyond 30: probing the -20<M_UV<-17 luminosity function at 8<z<13 with the NIRCam parallel field of the MIRI Deep Survey

We present the ultraviolet luminosity function and an estimate of the cosmic star formation rate density at $8 8$ galaxy candidates based on their dropout nature in the F115W and/or F150W filters, a high probability for their photometric redshifts, estimated with three different codes, being at $z>8$, good fits based on $χ^2$ calculations, and predominant solutions compared to $z<8$ alternatives. We find mild evolution in the luminosity function from $z\sim13$ to $z\sim8$, i.e., only a small increase in the average number density of $\sim$0.2 dex, while the faint-end slope and absolute magnitude of the knee remain approximately constant, with values $α=-2.2\pm0.1$ and $M^*=-20.8\pm0.2$ mag. Comparing our results with the predictions of state-of-the-art galaxy evolution models, we find two main results: (1) a slower increase with time in the cosmic star formation rate density compared to a steeper rise predicted by models; (2) nearly a factor of 10 higher star formation activity concentrated in scales around 2 kpc in galaxies with stellar masses $\sim10^8$ M$_\odot$ during the first 350 Myr of the Universe, $z\sim12$, with models matching better the luminosity density observational estimations $\sim$150 Myr later, by $z\sim9$.

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arXiv2023

A SPectroscopic survey of biased halos In the Reionization Era (ASPIRE): A First Look at the Rest-frame Optical Spectra of $z > 6.5$ Quasars Using JWST

Studies of rest-frame optical emission in quasars at $z>6$ have historically been limited by the wavelengths accessible by ground-based telescopes. The James Webb Space Telescope (JWST) now offers the opportunity to probe this emission deep into the reionization epoch. We report the observations of eight quasars at $z>6.5$ using the JWST/NIRCam Wide Field Slitless Spectroscopy, as a part of the ''A SPectroscopic survey of biased halos In the Reionization Era (ASPIRE)" program. Our JWST spectra cover the quasars' emission between rest frame $\sim$ 4100 and 5100 Å. The profiles of these quasars' broad H$β$ emission lines span a FWHM from 3000 to 6000 $\rm{km~s^{-1}}$. The H$β$-based virial black hole (BH) masses, ranging from 0.6 to 2.1 billion solar masses, are generally consistent with their MgII-based BH masses. The new measurements based on the more reliable H$β$ tracer thus confirm the existence of billion solar-mass BHs in the reionization epoch. In the observed [OIII] $λλ$4960,5008 doublets of these luminous quasars, broad components are more common than narrow core components ($\le~1200~\rm{km~s^{-1}}$), and only one quasar shows stronger narrow components than broad. Two quasars exhibit significantly broad and blueshifted [OIII] emission, thought to trace galactic-scale outflows, with median velocities of $-610~\rm{km~s^{-1}}$ and $-1430~\rm{km~s^{-1}}$ relative to the [CII] $158\,μ$m line. All eight quasars show strong optical FeII emission, and follow the Eigenvector 1 relations defined by low-redshift quasars. The entire ASPIRE program will eventually cover 25 quasars and provide a statistical sample for the studies of the BHs and quasar spectral properties.

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arXiv2023

A SPectroscopic survey of biased halos In the Reionization Era (ASPIRE): JWST Reveals a Filamentary Structure around a z=6.61 Quasar

We present the first results from the JWST ASPIRE program (A SPectroscopic survey of biased halos In the Reionization Era). This program represents an imaging and spectroscopic survey of 25 reionization-era quasars and their environments by utilizing the unprecedented capabilities of NIRCam Wide Field Slitless Spectroscopy (WFSS) mode. ASPIRE will deliver the largest ($\sim280~{\rm arcmin}^2$) galaxy redshift survey at 3-4 $μ$m among JWST Cycle-1 programs and provide extensive legacy values for studying the formation of the earliest supermassive black holes (SMBHs), the assembly of galaxies, early metal enrichment, and cosmic reionization. In this first ASPIRE paper, we report the discovery of a filamentary structure traced by the luminous quasar J0305-3150 and ten [OIII] emitters at $z=6.6$. This structure has a 3D galaxy overdensity of $δ_{\rm gal}=12.6$ over 637 cMpc$^3$, one of the most overdense structures known in the early universe, and could eventually evolve into a massive galaxy cluster. Together with existing VLT/MUSE and ALMA observations of this field, our JWST observations reveal that J0305-3150 traces a complex environment where both UV-bright and dusty galaxies are present, and indicate that the early evolution of galaxies around the quasar is not simultaneous. In addition, we discovered 31 [OIII] emitters in this field at other redshifts, $5.3<z<6.7$, with half of them situated at $z\sim5.4$ and $z\sim6.2$. This indicates that star-forming galaxies, such as [OIII] emitters, are generally clustered at high redshifts. These discoveries demonstrate the unparalleled redshift survey capabilities of NIRCam WFSS and the potential of the full ASPIRE survey dataset.

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arXiv2023

MINDS. The detection of $^{13}$CO$_{2}$ with JWST-MIRI indicates abundant CO$_{2}$ in a protoplanetary disk

We present JWST-MIRI MRS spectra of the protoplanetary disk around the low-mass T Tauri star GW Lup from the MIRI mid-INfrared Disk Survey (MINDS) GTO program. Emission from $^{12}$CO$_{2}$, $^{13}$CO$_{2}$, H$_{2}$O, HCN, C$_{2}$H$_{2}$, and OH is identified with $^{13}$CO$_{2}$ being detected for the first time in a protoplanetary disk. We characterize the chemical and physical conditions in the inner few au of the GW Lup disk using these molecules as probes. The spectral resolution of JWST-MIRI MRS paired with high signal-to-noise data is essential to identify these species and determine their column densities and temperatures. The $Q$-branches of these molecules, including those of hot-bands, are particularly sensitive to temperature and column density. We find that the $^{12}$CO$_{2}$ emission in the GW Lup disk is coming from optically thick emission at a temperature of $\sim$400 K. $^{13}$CO$_{2}$ is optically thinner and based on a lower temperature of $\sim$325 K, may be tracing deeper into the disk and/or a larger emitting radius than $^{12}$CO$_{2}$. The derived $N_{\rm{CO_{2}}}$/$N_{\rm{H_{2}O}}$ ratio is orders of magnitude higher than previously derived for GW Lup and other targets based on \textit{Spitzer}-IRS data. This high column density ratio may be due to an inner cavity with a radius in between the H$_{2}$O and CO$_{2}$ snowlines and/or an overall lower disk temperature. This paper demonstrates the unique ability of JWST to probe inner disk structures and chemistry through weak, previously unseen molecular features.

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arXiv2022

High Resolution HST Imaging Survey of Local Star-Forming Galaxies I: Spatially-Resolved Obscured Star Formation with H$α$ and Paschen-$β$ Recombination Lines

We present a sample of 24 local star-forming galaxies observed with broad- and narrow-band photometry from the Hubble Space Telescope, that are part of the GOALS survey of local luminous and ultra-luminous infrared galaxies. With narrow-band filters around the emission lines H$α$ (and [NII]) and Pa$β$, we obtain robust estimates of the dust attenuation affecting the gas in each galaxy, probing higher attenuation than can be traced by the optical Balmer decrement H$α$/H$β$ alone by a factor of $>1$ mag. We also infer the dust attenuation towards the stars via a spatially-resolved SED-fitting procedure that uses all available HST imaging filters. We use various indicators to obtain the star formation rate (SFR) per spatial bin, and find that Pa$β$ traces star-forming regions where the H$α$ and the optical stellar continuum are heavily obscured. The dust-corrected Pa$β$ SFR recovers the 24$μ$m-inferred SFR with a ratio $-0.14\pm0.32$ dex and the SFR inferred from the $8\mathrm{-}1000\,μ\mathrm{m}$ infrared luminosity at $-0.04\pm0.23$ dex. Both in a spatially-resolved and integrated sense, rest-frame near infrared recombination lines can paint a more comprehensive picture of star formation across cosmic time, particularly with upcoming JWST observations of Paschen-series line emission in galaxies as early as the epoch of reionization.

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arXiv2021

The UV-brightest Lyman continuum emitting star-forming galaxy

We report the discovery of J0121+0025, an extremely luminous and young star-forming galaxy (M_UV = -24.11, log[L_Lya / erg s^-1] = 43.8) at z = 3.244 showing copious Lyman continuum (LyC) leakage (f_esc,abs ~ 40%). High signal-to-noise ratio rest-frame UV spectroscopy with the Gran Telescopio Canarias reveals a high significance (7.9 sigma) emission below the Lyman limit (< 912A), with a flux density level f_900A = 0.78 +/- 0.10 uJy, and strong P-Cygni in wind lines of OVI 1033A, NV 1240A and CIV 1550A that are indicative of a young age of the starburst (<10 Myr). The spectrum is rich in stellar photospheric features, for which a significant contribution of an AGN at these wavelengths is ruled out. Low-ionization ISM absorption lines are also detected, but are weak (EW0 ~ 1A) and show large residual intensities, suggesting a clumpy geometry of the gas with a non-unity covering fraction or a highly ionized ISM. The contribution of a foreground and AGN contamination to the LyC signal is unlikely. Deep optical to Spitzer/IRAC 4.5um imaging show that the spectral energy distribution of J0121+0025 is dominated by the emission of the young starburst, with log(M*/Msun) = 9.9 +/- 0.1 and SFR = 981 +/- 232 Msun yr^-1. J0121+0025 is the most powerful LyC emitter known among the star-forming galaxy population. The discovery of such luminous and young starburst leaking LyC radiation suggests that a significant fraction of LyC photons can escape in sources with a wide range of UV luminosities and are not restricted to the faintest ones as previously thought. These findings might shed further light on the role of luminous starbursts to the cosmic reionization.

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arXiv2021

Stellar kinematics in the nuclear regions of nearby LIRGs with VLT-SINFONI. Comparison with gas phases and implications for dynamical mass estimations

In this work we use seeing-limited SINFONI H- and K-band spectroscopy to analyse the spatially resolved kinematics of the stellar component in the inner r<1-2 kpc of ten nearby (mean z=0.014) LIRGs. We compare the stellar kinematics with those for different gas phases, and analyse the relative effects of using different tracers when estimating dynamical masses. The stellar velocity and velocity dispersion maps are extracted in both near-IR bands by fitting the continuum emission using pPXF while we use the gas kinematics from previous works. We find that the different gas phases have similar kinematics, whereas the stellar component is rotating with slightly lower velocities (V$_*$~0.8V$_g$) but in significantly warmer orbits ($σ_*$~2$σ_g$) than the gas phases. These values indicate that stars are rotating in thick discs while the gas phases are confined in dynamically cooler rotating discs. However, these differences do not lead to significant discrepancies between the dynamical mass estimations based on the stellar and gas kinematics. This result suggests that the gas kinematics can be used to estimate M$_{dyn}$ also in z~2 SFGs, a galaxy population that shares many structural and kinematic properties with local LIRGs.

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arXiv2020

A proto-pseudobulge in ESO 320-G030 fed by a massive molecular inflow driven by a nuclear bar

Galaxies with nuclear bars are believed to efficiently drive gas inward, generating a nuclear starburst and possibly an active galactic nucleus (AGN). We confirm this scenario for the isolated, double-barred, luminous infrared galaxy ESO 320-G030 based on an analysis of Herschel and ALMA spectroscopic observations. Herschel/PACS and SPIRE observations of ESO 320-G030 show absorption/emission in 18 lines of H2O, which we combine with the ALMA H2O 423-330 448 GHz line (Eupper~400 K) and continuum images to study the nuclear region. Radiative transfer models indicate that 3 nuclear components are required to account for the H2O and continuum data. An envelope, with R~130-150 pc, T_dust~50 K, and N_H2~2x10^{23} cm^{-2}, surrounds a nuclear disk with R~40 pc and tau_100um~1.5-3 (N_H2~2x10^{24} cm^{-2}) and an extremely compact (R~12 pc), warm (~100 K), and buried (tau_100um>5, N_H2>~5x10^{24} cm^{-2}) core component. The three nuclear components account for 70% of the galaxy L_IR (SFR~16-18 Msun yr^{-1}). The nucleus is fed by a molecular inflow observed in CO 2-1 with ALMA, which is associated with the nuclear bar. With decreasing radius (r=450-225 pc), the mass inflow rate increases up to ~20 Msun yr^{-1}, which is similar to the nuclear SFR, indicating that the starburst is sustained by the inflow. At lower r, the inflow is best probed by the far-infrared OH ground-state doublets, with an estimated inflow rate of ~30 Msun yr^{-1}. The short timescale of ~20 Myr for nuclear gas replenishment indicates quick secular evolution, and indicates that we are witnessing an intermediate stage (<100 Myr) proto-pseudobulge fed by a massive inflow that is driven by a strong nuclear bar. We also apply the H2O model to the Herschel far-infrared spectroscopic observations of H2^{18}O, OH, $^{18}OH, OH+, H2O^+, H3O^+, NH, NH2, NH3, CH, CH^+, ^{13}CH^+, HF, SH, and C3, and estimate their abundances.

astro-ph.GA↗
arXiv2019

Properties of ionized outflows in MaNGA DR2 galaxies

We present the results from a systematic search and characterization of ionized outflows in nearby galaxies using the data from the second Data Release of the MaNGA Survey (DR2; > 2700 galaxies, z < 0.015). Using the spatially-resolved spectral information provided by the MANGA data, we have identified ~5200 Halpha-emitting regions across the galaxies and searched for signatures of ionized outflows. We find evidence for ionized outflows in 105 regions from 103 galaxies, roughly 7% of all the Halpha-emitting galaxies identified in this work. Our analysis allows us to study ionized outflows in individual regions with SFRs down to ~0.01 Msun yr-1, extending the ranges probed by previous works. The kinematics of the outflowing gas are strongly linked to the type of ionization mechanism: regions characterized by LIER emission host outflows with more extreme kinematics (FWHM_broad ~900 km/s), followed by those originated in AGN (~550 km/s), `Intermediate' (~450 km/s) and SF (~350 km/s) regions. Moreover, in most of the outflows we find evidence for gas ionized by shocks. We find a trend for higher outflow kinematics towards larger stellar masses of the host galaxies but no significant variation as a function of star formation. The fraction of outflowing gas that can escape from galaxies decreases towards higher dynamical masses, contributing to the preservation of the mass-metallicity relation by regulating the amount of metals in galaxies. Finally, assuming that the extensions of the outflows are significantly larger than the individual star-forming regions, as found in previous works, our results also support the presence of star formation within ionized outflows, as recently reported by Maiolino et al. 2017 and Gallagher et al. 2019.

astro-ph.GA↗
arXiv2018

A SINFONI view of the nuclear activity and circumnuclear star formation in NGC 4303 - II: Spatially resolved stellar populations

We present a spatially resolved stellar population study of the inner $\sim$200\,pc radius of NGC4303 based on near-infrared integral field spectroscopy with SINFONI/VLT at a spatial resolution of 40-80pc and using the STARLIGHT code. We found the distribution of the stellar populations presents a spatial variation, suggesting an age stratification. Three main structures stand out. Two nuclear blobs, one composed by young stars (t $\leq$ 50Myr) and one with intermediate-age stars (50Myr $<$ t $\leq$ 2Gyr) both shifted from the centre. The third one is an internal intermediate-age spiral arm-like structure, surrounding the blob of young stars. Our results indicate star formation has occurred through multiple bursts in this source. Furthermore, the youngest stellar populations (t $\lesssim$ 2Gyr) are distributed along a circumnuclear star-forming ring with r$\sim$250pc. The ring displays star formation rates (SFRs) in the range of 0.002-0.14M$_{\odot}$yr$^{-1}$, favoring the `pearls-on-a-string' scenario. The old underlying bulge stellar population component (t $>$ 2Gyr) is distributed outside the two blob structures. For the nuclear region (inner $\sim$60pc radius) we derived a SFR of 0.43\,M$_{\odot}$yr$^{-1}$ and found no signatures of non-thermal featureless continuum and hot dust emission, supporting the scenario in which a LLAGN/LINER-like source is hidden in the centre of NGC4303. Thus, our results reveal a rather complex star formation history in NGC4303, with different stellar population components coexisting with a low efficiency accreting black hole in its centre.

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