arXiv subjects

V. Reynaldi

Publications and source records attributed to V. Reynaldi.

13 recordsLinked to original sources

arXiv2026

JWST resolves jet-driven H2 and ionized outflows in radio galaxy 3C305

We present JWST MIRI MRS, NIRSpec, NIRCam, and MIRI imaging observations of 3C 305, a radio galaxy with a compact jet that is confined within the galaxy. We use the H2 0-0 S(1)-S(7) lines, several mid-IR fine-structure lines, and PAH emission in the MIRI MRS spectrum to conduct a multiphase study of the radio jet's impact on the interstellar medium. Multiple tracers, including H2/PAH 11.3 um and [Fe II] 5.34 um, provide evidence for shocks at the jet termination locations. Two Gaussian components are required to reproduce the warm H2 kinematics adequately, with one representing the bulk low-velocity component and the other corresponding to an outflow. The ionized gas reaches higher outflow velocities than the H2 gas, and the sharp increase in velocity at the jet hotspots points to jet-driven outflows. We fit the H2 excitation diagram with a power-law temperature distribution and find that the hotspots exhibit flatter slopes, indicating a larger warm/hot gas mass fraction at these locations. Our MAPPINGS line-ratio analysis indicates that most of the mid-IR ionized gas can be fit by a shock-plus-precursor model. We find that strong radiative losses dominated by line cooling, together with moderate kinetic power in the molecular and ionized gas outflows, can account for the estimated jet power, indicating high jet coupling efficiency in 3C 305. Together with other studies of multiphase gas, our results show that jets can efficiently shock-heat and accelerate the gas they encounter, driving massive, kiloparsec-scale, multiphase outflows.

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arXiv2025

High-resolution radio imaging of TGSSJ1530+1049, a radio galaxy in a dense environment at z=4

High-redshift radio galaxies can provide insights into the structure formation and galaxy evolution at earlier cosmological epochs. TGSSJ1530+1049 was selected as a candidate high-redshift radio galaxy. Subsequent observations with the James Webb Space Telescope (JWST) presented in a companion paper (Saxena et al., 2026) have shown that it is located at a redshift z=4.0. The JWST data furthermore showed that the radio source is part of one of the densest structures of galaxies and ionized gas known at these redshifts. The complex system qualitatively resembles a massive (cluster) galaxy forming early through a rapid succession of mergers. TGSSJ1530+1049 is an unresolved source down to ~0.6" scale in multiple radio surveys. To reveal its high-resolution radio structure and allow for a detailed comparison with JWST observations, we studied its morphology at various angular scales with different radio interferometric instruments. We observed TGSSJ1530+1049 at milliarcsecond (mas) scale angular resolution with the European VLBI Network (EVN), and at ~100-mas scale resolution with the enhanced Multi-Element Remotely Linked Interferometer Network (e-MERLIN). We recovered a complex north--south oriented structure with steep-spectrum radio-emitting features, which are associated with lobes and hot spots of a jetted active galactic nucleus. The centre of the radio galaxy proved to be too faint at cm wavelengths to be unambiguously detected in our observations. Nevertheless, the linear size (~5.5 kpc) and the radio power place it among the so-called medium-sized symmetric objects, a smaller and/or confined version of larger radio galaxies. Comparison between the radio morphology and that of the ionized gas observed by JWST shows that the two are closely aligned. However, the optical emission line gas extends out to ~25 kpc, which is well beyond the detected radio structures. (Abridged)

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arXiv2025

Shocked, Heated, and Now Resolved: H$_2$ excitation in the low-luminosity AGN at M58 core with JWST

We present JWST NIRSpec and MIRI MRS observations of the central kiloparsec of M58 (NGC 4579), a nearby LINER galaxy hosting a low-luminosity AGN (LLAGN; $L_\mathrm{bol} \sim 10^{42}$ erg s$^{-1}$) with a low-power jet. These data provide an unprecedented view of the warm molecular gas phase and reveal clear signatures of feedback. We detect 44 H$_2$ lines, including bright pure rotational lines (S(1)-S(18)) and rovibrational lines up to $\nu=2$, probing a wide range of excitation conditions. Excitation diagrams show that rotational lines follow a power-law temperature distribution with an exponential cutoff, consistent with heating by low-velocity shocks. H$_2$ rovibrational lines deviate from thermal models primarily because of sub-thermal excitation at low density. Additionally, there may be a 10% contribution powered by AGN X-ray photons in the nucleus. The dust lanes associated with the spiral inflow appear dynamically undisturbed but show signs of shock heating, while the inner $\sim$200 pc exhibits turbulent kinematics produced by outflowing molecular gas. These results reveal the subtle yet measurable impact of LLAGN feedback on the interstellar medium, demonstrating that even weak, vertically oriented jets and low radiative accretion rates can perturb molecular gas and regulate nuclear reservoirs. This study highlights JWST's transformative ability to uncover hidden modes of AGN feedback.

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arXiv2025

The JWST View of Cygnus A: Jet-Driven Coronal Outflow with a Twist

We present first results from James Webb Space Telescope (JWST) Near-Infrared Spectrograph (NIRSpec), Mid-Infrared Instrument (MIRI), and Keck Cosmic Webb Imager (KCWI) integral field spectroscopy of the powerful but highly obscured host-galaxy of the jetted radio source Cygnus A. We detect 169 infrared emission lines at 1.7--27 micron and explore the kinematics and physical properties of the extended narrow-line region (NLR) in unprecedented detail. The density-stratified NLR appears to be shaped by the initial blow-out and ongoing interaction of the radio jet with the interstellar medium, creating a multi-phase bicone with a layered structure composed of molecular and ionized gas. The NLR spectrum, with strong coronal emission at kpc-scale, is well-modeled by AGN photoionization. We find evidence that the NLR is rotating around the radio axis, perhaps mediated by magnetic fields and driven by angular momentum transfer from the radio jet. The overall velocity field of the NLR is well described by 250 km/s outflow along biconical spiral flow lines, combining both rotation and outflow signatures. There is particularly bright [Fe II] 1.644 micron emission from a dense, high-velocity dispersion, photoionized clump of clouds found near the projected radio axis. Outflows of 600--2000 km/s are found in bullets and streamers of ionized gas that may be ablated by the radio jet from these clouds, driving a local outflow rate of 40 Msun/yr.

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arXiv2023

Powerful Radio Sources in the Southern Sky. II. A SWIFT X-Ray Perspective

We recently constructed the G4Jy-3CRE, a catalog of extragalactic radio sources based on the GLEAM 4-Jy (G4Jy) sample, with the aim of increasing the number of powerful radio galaxies and quasars with similar selection criteria to those of the revised release of the Third Cambridge catalog (3CR). The G4Jy-3CRE consists of a total of 264 radio sources mainly visible from the Southern Hemisphere. Here, we present an initial X-ray analysis of 89 G4Jy-3CRE radio sources with archival X- ray observations from the Neil Gehrels Swift Observatory. We reduced a total of 615 Swift observations, for about 0.89 Msec of integrated exposure time, we found X-ray counterparts for 61 radio sources belonging to the G4Jy-3CRE, 11 of them showing extended X-ray emission. The remaining 28 sources do not show any X-ray emission associated with their radio cores. Our analysis demonstrates that X-ray snapshot observations, even if lacking uniform exposure times, as those carried out with Swift, allow us to (i) verify and/or re ne the host galaxy identi cation; (ii) discover the extended X-ray emission around radio galaxies of the intracluster medium when harbored in galaxy clusters, as the case of G4Jy 1518 and G4Jy 1664, and (iii) detect X-ray radiation arising from their radio lobes, as for G4Jy 1863.

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arXiv2023

Powerful Radio Sources in the Southern Sky. I. Optical Identifications

Since the early sixties, our view of radio galaxies and quasars has been drastically shaped by discoveries made thanks to observations of radio sources listed in the Third Cambridge catalog and its revised version (3CR). However, the largest fraction of data collected to date on 3CR sources was performed with relatively old instruments, rarely repeated and/or updated. Importantly, the 3CR contains only objects located in the Northern Hemisphere thus having limited access to new and innovative astronomical facilities. To mitigate these limitations we present a new catalog of powerful radio sources visible from the Southern Hemisphere, extracted from the GLEAM 4-Jy (G4Jy) catalog and based on equivalent selection criteria as the 3CR. This new catalog, named G4Jy- 3CRE, where the E stands for "equivalent", lists a total of 264 sources at declination below -5 degrees and with 9 Jy limiting sensitivity at ~178 MHz. We explored archival radio maps obtained with different surveys and compared then with optical images available in the Pan-STARRS, DES and DSS databases to search for optical counterparts of their radio cores. We compared mid-infrared counterparts, originally associated in the G4Jy, with the optical ones identified here and we present results of a vast literature search carried out to collect redshift estimates for all G4Jy-3CRE sources resulting in a total of 145 reliable z measurements.

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arXiv2022

Disentangling the nature of the prototype radio weak BL Lac: Contemporaneous multifrequency observations of WISE J141046.00 + 740511.2

Context. The gamma-ray emitting source WISE J141046.00+740511.2 has been associated with a Fermi-LAT detection by crossmatching with Swift/XRT data. It has shown all the canonical observational characteristics of a BL Lac source, including a power-law, featureless optical spectrum. However, it was only recently detected at radio frequencies and its radio flux is significantly low. Aims. Given that a radio detection is fundamental to associate lower-energy counterparts to Fermi-LAT sources, we aim to unambiguously classify this source by performing a multiwavelength analysis based on contemporaneous data. Methods. By using multifrequency observations at the Jansky Very Large Array, Giant Metrewave Radio Telescope, Gran Telescopio Canarias, Gemini, William Herschel Telescope and Liverpool observatories, together with Fermi-LAT and Swift data, we carried out two kinds of analyses. On one hand, we studied several known parameters that account for the radio loudness or weakness characterization and their application to blazars (in general) and to our source (in particular). And, on the other hand, we built and analyzed the observed spectral energy distribution (SED) of this source to try to explain its peculiar characteristics. Results. The multiwavelength analysis indicates that WISE J141046.00+740511.2 is a blazar of the high-frequency peaked (HBL) type that emits highly polarized light and that is likely located at a low redshift. In addition, the one-zone model parameters that best fit its SED are those of an extreme HBL (EHBL); this blazar type has been extensively predicted in theory to be lacking in the radio emission that is otherwise typical of canonical gamma-ray blazars. Conclusions. We confirm that WISE J141046.00+740511.2 is indeed a highly polarized BL Lac of the HBL type. Further studies will be conducted to explain the atypical low radio flux detected for this source.

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arXiv2021

The ionised gas outflow in the Circinus galaxy: kinematics and physical conditions

We employ MUSE/VLT data to study the ionised and highly ionised gas phases of the feedback in Circinus, the closest Seyfert 2 galaxy to us. The analysis of the nebular emission allowed us to detect a remarkable high-ionisation gas outflow beyond the galaxy plane traced by the coronal lines [Fe VII] $\lambda$6089 and [Fe X] $\lambda$6374, extending up to 700 pc and 350 pc NW from the nucleus, respectively. This is the first time that the [Fe X] emission is observed at such distances from the central engine in an AGN. The gas kinematics reveals expanding gas shells with velocities of a few hundred km s$^{-1}$, spatially coincident with prominent hard X-ray emission detected by Chandra. Density and temperature sensitive line ratios show that the extended high-ionisation gas is characterized by a temperature reaching 25000 K and an electron density > 10$^2$ cm$^{-3}$. We found that local gas excitation by shocks produced by the passage of a radio jet leads to the spectacular high-ionisation emission in this object. This hypothesis is fully supported by photoionisation models that accounts for the combined effects of the central engine and shocks. They reproduce the observed emission line spectrum at different locations inside and outside of the NW ionisation cone. The energetic outflow produced by the radio jet is spatially located close to an extended molecular outflow recently reported using ALMA which suggests that they both represent different phases of the same feedback process acting on the AGN.

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arXiv2021

The Fornax Cluster through S-PLUS

The Southern Photometric Local Universe Survey (S-PLUS) aims to map $\approx$ 9300 deg$^2$ of the Southern sky using the Javalambre filter system of 12 optical bands, 5 Sloan-like filters and 7 narrow-band filters centered on several prominent stellar features ([OII], Ca H+K, D4000, H$_{\delta}$, Mgb, H$_{\alpha}$ and CaT). S-PLUS is carried out with the T80-South, a new robotic 0.826-m telescope located on CTIO, equipped with a wide FoV camera (2 deg$^2$). In this poster we introduce project #59 of the S-PLUS collaboration aimed at studying the Fornax galaxy cluster covering an sky area of $\approx$ 11 $\times$ 7 deg$^2$, and with homogeneous photometry in the 12 optical bands of S-PLUS (Coordinator: A. Smith Castelli).

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arXiv2020

On the origin of X-ray oxygen emission-lines in obscured AGN

We present the Catalog of High REsolution Spectra of Obscured Sources (CHRESOS) from the XMM-Newton Science Archive. It comprises the emission-line luminosities of H- and He-like transitions from C to Si, and the Fe 3C and Fe 3G L-shell ones. Here, we concentrate on the soft X-ray OVII(f) and OVIII Ly_alpha emission lines to shed light onto the physical processes with which their formation can be related to: active galactic nucleus vs. star forming regions. We compare their luminosity with that of two other important oxygen key lines [OIII]5007A, in the optical, and [OIV]25.89mic, in the IR. We also test OVII(f) and OVIIILy_alpha luminosities against that of continuum bands in the IR and hard X-rays, which point to different ionization processes. We probe into those processes by analyzing photoionization and colisional ionization model predictions upon our lines. We show that both scenarios can explain the formation and observed intensities of OVII(f) and OVIII Ly_alpha. By analyzing the relationships between OVII(f) and OVIII Ly_alpha, and all other observables: [OIII]5007A, [OIV]25.89mic emission lines, and MIR-12mic, FIR-60mic, FIR-100mic, 2-10 keV and 14-195 keV continuum bands, we conclude that the AGN radiation field is mainly responsible of the soft X-ray oxygen excitation.

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arXiv2020

Optical spectroscopic classification of 35 hard X-ray sources from the Swift-BAT 70-month catalogue

The nature of a substantial percentage (about one fifth) of hard X-ray sources discovered with the BAT instrument onboard the Neil Gehrels Swift Observatory (hereafter Swift) is unknown because of the lack of an identified longer-wavelength counterpart. Without such follow-up, an X-ray catalogue is of limited astrophysical value: we therefore embarked, since 2009, on a long-term project to uncover the optical properties of sources identified by Swift by using a large suite of ground-based telescopes and instruments. In this work, we continue our programme of characterization of unidentified or poorly studied hard X-ray sources by presenting the results of an optical spectroscopic campaign aimed at pinpointing and classifying the optical counterparts of 35 hard X-ray sources taken from the 70-month BAT catalogue. (...) With the use of optical spectra taken at six different telescopes we were able to identify the main spectral characteristics (continuum type, redshift, and emission or absorption lines) of the observed objects, and determined their nature. We identify and characterize a total of 41 optical candidate counterparts corresponding to 35 hard X-ray sources given that, because of positional uncertainties, multiple lower energy counterparts can sometimes be associated with higher energy detections. We discuss which ones are the actual (or at least most likely) counterparts based on our observational results. In particular, 31 sources in our sample are active galactic nuclei: 16 are classified as Type 1 (with broad and narrow emission lines) and 13 are classified as Type 2 (with narrow emission lines only); two more are BL Lac-type objects. We also identify one LINER, one starburst, and 3 elliptical galaxies. The remaining 5 objects are galactic sources: we identify 4 of them as cataclysmic variables, whereas one is a low mass X-ray binary.

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arXiv2015

The fingerprints of Photoionization and Shock-Ionization in two CSS sources

We investigate the ionization state of the Extended Emission-Line Regions (EELRs) around two compact steep-spectrum (CSS) radio galaxies, 3C~268.3 and 3C~303.1, in order to identify the contribution of photoionization and shock-ionization. We perform a new spectroscopical (long-slit) analysis with GMOS/Gemini with the slit oriented in the radio-jet direction, where outflows are known to exist. The [Ne V]$\lambda 3426$ emission is the most interesting feature of the spectra and the key to breaking the degeneracy between the models: since this emission-line is more extended than HeII, it challenges the ionization structure proposed by any photoionization model, also its intensity relative to H$\beta$ does not behave as expected with respect to the ionization parameter U in the same scenario. On the contrary, when it is compared to the intensity of [OII]$\lambda3727$/H$\beta$ and all these results are joined, the whole scenario is plausible to be explained as emission coming from the hot, compressed, shocked gas in shock-ionization models. Although the model fitting is strongly sensitive to the chosen line-ratios, it argues for the presence of external and strong ionizing fields, such as the precursor field created by the shock or/and the AGN radiation field. In this paper, we show how AGN photoionization and shock-ionization triggered by jet-cloud interaction work together in these EELRs in order to explain the observed trends and line-ratio behaviours in a kinematically acceptable way.

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arXiv2013

Searching for evidence of jet-cloud interaction in radio galaxies. First results for 3C 381

We present results of Gemini spectroscopy and Hubble Space Telescope imaging of the 3C~381 radio galaxy. Possible ionising mechanisms for the Extended Emission-Line Region were studied through state-of-the-art diagnostic analysis employing line-ratios. Photoionisation from the central engine as well as mixed-medium photoionisation models fail in reproducing both the strengths and the behaviour of the highest-excitation lines, such as [NeV]3424, HeII, and [OIII}]5007, which are measured at very large distances from the AGN. Shock-ionisation models provide a better fit to the observation. Expanding shocks with velocities higher than 500 km/s are capable of reaching the observed intensity ratios for lines with different ionisation states and excitation degrees. This model also provide a direct explanation of the mechanical energy input needed to explain the high-velocity line-splitting observed in the velocity field.

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