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I. Prandoni

Publications and source records attributed to I. Prandoni.

At least 37 records · Page 2Linked to original sources
arXiv2025

Spectroscopic confirmation of a dust-obscured, metal-rich dwarf galaxy at z~5

We present the first spectroscopic confirmation of a dust-obscured dwarf galaxy, CEERS-14821. The analysis is performed combining JWST NIRCam broad-band photometry and NIRSpec/PRISM spectroscopic data. From the detection of multiple rest-frame optical lines, we derive that CEERS-14821 is located at $z=4.883\pm0.003$. Moreover, from a secure detection of the $H_α$ and $H_β$ we derived that the galaxy has a dust extinction ranging from Av=2.2 to Av=3.3, depending on the assumed reddening law. This value is extremely large given that we estimated a low stellar mass around log(M/Mo)=8.0-8.2. Moreover, using different metallicity tracers, we verify that the galaxy is also metal-rich, with 12+log(O/H)>8.3. This is well above the expectation from both the mass-metallicity relation and the fundamental mass-metalliticy relation. CEERS-14821 is going through a burst of star formation, there are no indications of a strong contribution from an active galactic nuclei (f(AGN)<0.5 with respect to the total dust luminosity). Based on the rest-frame optical images, this source has a size compatible with galaxies of similar stellar mass and redshift. Finally, with the current data, it seems that there are galaxies closely interacting with CEERS-14821.

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arXiv2025

The LOFAR Two-metre Sky Survey: Deep Fields Data Release 2. I. The ELAIS-N1 field

We present the final 6'' resolution data release of the ELAIS-N1 field from the LOw-Frequency ARray (LOFAR) Two-metre Sky Survey Deep Fields project (LoTSS Deep). The 144MHz images are the most sensitive achieved to date at this frequency and were created from 290 TB of data obtained from 505 hrs on-source observations taken over 7.5 years. The data were processed following the strategies developed for previous LoTSS and LoTSS Deep data releases. The resulting images span 24.53 square degrees and, using a refined source detection approach, we identified 154,952 radio sources formed from 182,184 Gaussian components within this area. The maps reach a noise level of 10.7 $μ$Jy/beam at 6'' resolution where approximately half of the noise is due to source confusion. In about 7.4% of the image our limited dynamic range around bright sources results in a further > 5% increase in the noise. The images have a flux density scale accuracy of about 9% and the standard deviation of offsets between our source positions and those from Pan-STARRS is 0.2'' in RA and Dec for high significance detections. We searched individual epoch images for variable sources, identifying 39 objects with considerable variation. We also searched for circularly polarised sources achieving three detections of previously known emitters (two stars and one pulsar) whilst constraining the typical polarisation fraction plus leakage to be less than 0.045%.

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arXiv2024

LOFAR Deep Fields: Probing the sub-mJy regime of polarized extragalactic sources in ELAIS-N1. II. Analysis

Deep polarization surveys at low radio frequencies are key to cosmic magnetism studies: Larger catalogs of polarized extragalactic sources and increased precision on Faraday rotation measures (RMs) make it possible to probe the magneto-ionic medium along the lines of sight of the sources and to construct denser RM grids. In a first paper, we presented a search for polarized sources in deep observations of the 25 square degree area of the European Large Area ISO Survey North 1 (ELAIS-N1) field with the LOw Frequency ARray (LOFAR) in the range 114.9 to 177.4 MHz. In this paper, we investigate the properties of the polarized radio galaxies and use the catalog to produce an RM grid of the field. After identifying the host galaxies and collecting redshift information, we characterized the radio galaxies in terms of their radio morphologies, rest frame radio luminosities, and linear sizes. We calculated residual rotation measures (RRMs) by removing the Galactic RM and studied the variation in the RRMs with redshift and degree of polarization. We produced an RRM grid of the field and compared the positions of the polarized sources with those of galaxy clusters and superclusters. The radio galaxies show a variety of morphologies, including diffuse emission; Fanaroff Riley type II sources make up about half of the sample. Using available multiband catalogs, we found redshifts for the hosts of all polarized sources in the range of 0.06 to 1.9. Polarized emission is detected mainly from large radio galaxies. The RRM values have a median close to zero, and they appear to be independent of redshift and degree of polarization. The sources in the lines of sight of clusters of galaxies and of a supercluster are indistinguishable in their polarization and RRM properties from the population of sources that are not behind these structures.

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arXiv2024

Radio-AGN activity across the galaxy population: dependence on stellar mass, star-formation rate, and redshift

We characterise the co-evolution of radio-loud AGN and their galaxies by mapping the dependence of radio-loud AGN activity on stellar mass and star-formation rate (SFR) across cosmic time (out to $z \sim 1.5$). Deep LOFAR radio observations are combined with large galaxy samples to study the incidence of radio-loud AGN across the galaxy population; the AGN are further split into low-excitation radio galaxies (LERGs) and high-excitation radio galaxies (HERGs). We find that LERG activity occurs over a wide range of SFRs, whereas HERGs are typically found in galaxies with ongoing star formation. The LERGs are then split based on their SFRs relative to the main sequence, across redshift. Within quiescent galaxies, LERG activity shows a steep stellar mass dependence with the same normalisation across the past $\sim$ 10 Gyr; this indicates that hot gas fuels LERGs in quiescent galaxies across cosmic time. In massive galaxies ($\log_{10}(M/\rm{M_{\odot}}) \gtrsim 11$), the incidence of LERGs is roughly constant across the galaxy population, suggesting that LERGs in massive galaxies may be fuelled by hot gas regardless of the star-formation activity. At lower masses, however, LERG activity is significantly more enhanced (by a factor of up to 10) in star-forming galaxies compared to quiescent galaxies; this suggests that an additional fuelling mechanism, likely associated with cold gas, may fuel the LERGs in galaxies with higher SFRs. We find that HERGs typically accrete above 1 per cent of the Eddington-scaled accretion rate, and the LERGs typically accrete below this level.

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arXiv2024

Euclid preparation. XLIX. Selecting active galactic nuclei using observed colours

Euclid will cover over 14000 $deg^{2}$ with two optical and near-infrared spectro-photometric instruments, and is expected to detect around ten million active galactic nuclei (AGN). This unique data set will make a considerable impact on our understanding of galaxy evolution and AGN. In this work we identify the best colour selection criteria for AGN, based only on Euclid photometry or including ancillary photometric observations, such as the data that will be available with the Rubin legacy survey of space and time (LSST) and observations already available from Spitzer/IRAC. The analysis is performed for unobscured AGN, obscured AGN, and composite (AGN and star-forming) objects. We make use of the spectro-photometric realisations of infrared-selected targets at all-z (SPRITZ) to create mock catalogues mimicking both the Euclid Wide Survey (EWS) and the Euclid Deep Survey (EDS). Using these catalogues we estimate the best colour selection, maximising the harmonic mean (F1) of completeness and purity. The selection of unobscured AGN in both Euclid surveys is possible with Euclid photometry alone with F1=0.22-0.23, which can increase to F1=0.43-0.38 if we limit at z>0.7. Such selection is improved once the Rubin/LSST filters (a combination of the u, g, r, or z filters) are considered, reaching F1=0.84 and 0.86 for the EDS and EWS, respectively. The combination of a Euclid colour with the [3.6]-[4.5] colour, which is possible only in the EDS, results in an F1-score of 0.59, improving the results using only Euclid filters, but worse than the selection combining Euclid and LSST. The selection of composite ($f_{\rm AGN}$=0.05-0.65 at 8-40 $μm$) and obscured AGN is challenging, with F1<0.3 even when including ancillary data. This is driven by the similarities between the broad-band spectral energy distribution of these AGN and star-forming galaxies in the wavelength range 0.3-5 $μm$.

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arXiv2024

LOFAR Deep Fields: Probing the sub-mJy regime of polarized extragalactic sources in ELAIS-N1. I. The catalog

The aim of this study is to probe the sub-mJy polarized source population with LOFAR. We present the method used to stack LOFAR polarization datasets, the resulting catalog of polarized sources, and the derived polarized source counts. The ELAIS-N1 field was selected for a polarimetric study at 114.9-177.4 MHz. A total area of 25 deg2 was imaged at 6"- resolution in the Stokes Q and U parameters. Alignment of polarization angles was done both in frequency and in Faraday space before stacking datasets from 19 eight-hour-long epochs. A search for polarized sources was carried out in the final, stacked dataset, and the properties of the detected sources were examined. The depolarization level of sources known to be polarized at 1.4 GHz was quantified. A one-sigma noise level of 19 μJy/beam was reached in the central part of the field after stacking. Twenty-five polarized sources were detected above 8σ, five of which had not been detected in polarization at any other radio frequencies before. Seven additional polarized components were found by lowering the threshold to 6σat positions corresponding to sources known to be polarized at 1.4 GHz. In two radio galaxies, polarization was detected from both radio lobes, so the final number of associated radio continuum sources is 31. The detected sources are weakly polarized, with a median degree of polarization of 1.75% for the sample of sources detected in polarized emission. The sources previously detected in polarization at 1.4 GHz are significantly depolarized at 150 MHz. The catalog is used to derive the polarized source counts at 150 MHz. This is the deepest and highest-resolution polarization study at 150 MHz to date.

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arXiv2024

A novel Bayesian approach for decomposing the radio emission of quasars: I. Modelling the radio excess in red quasars

Studies show that both radio jets from the active galactic nuclei (AGN) and the star formation (SF) activity in quasar host galaxies contribute to the quasar radio emission; yet their relative contributions across the population remain unclear. Here, we present an improved parametric model that allows us to statistically separate the SF and AGN components in observed quasar radio flux density distributions, and investigate how their relative contributions evolve with AGN bolometric luminosity ($L_\mathrm{bol}$) and redshift ($z$) using a fully Bayesian method. Based on the newest data from LOFAR Two-Metre Sky Survey Data Release 2, our model gives robust fitting results out to $z\sim4$, showing a quasar host galaxy SFR evolution that increases with bolometric luminosity and with redshift out to $z\sim4$. This differs from the global cosmic SFR density, perhaps due to the importance of galaxy mergers. The prevalence of radio AGN emissions increases with quasar luminosity, but has little dependence on redshift. Furthermore, our new methodology and large sample size allow us to subdivide our dataset to investigate the role of other parameters. Specifically, in this paper, we explore quasar colour and demonstrate that the radio excess in red quasars is due to an enhancement in AGN-related emission, since the host galaxy SF contribution to the total radio emission is independent of quasar colour. We also find evidence that this radio enhancement occurs mostly in quasars with weak or intermediate radio power.

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arXiv2024

How does the radio enhancement of broad absorption line quasars relate to colour and accretion rate?

The origin of radio emission in different populations of radio-quiet quasars is relatively unknown, but recent work has uncovered various drivers of increased radio-detection fraction. In this work, we pull together three known factors: optical colour ($g-i$), \CIV Distance (a proxy for $L/L_{Edd}$) and whether or not the quasar contains broad absorption lines (BALQSOs) which signify an outflow. We use SDSS DR14 spectra along with the LOFAR Two Metre Sky Survey Data Release 2 and find that each of these properties have an independent effect. BALQSOs are marginally more likely to be radio-detected than non-BALQSOs at similar colours and $L/L_{Edd}$, moderate reddening significantly increases the radio-detection fraction and the radio-detection increases with $L/L_{Edd}$ above a threshold for all populations. We test a widely used simple model for radio wind shock emission and calculate energetic efficiencies that would be required to reproduce the observed radio properties. We discuss interpretations of these results concerning radio-quiet quasars more generally. We suggest that radio emission in BALQSOs is connected to a different physical origin than the general quasar population since they show different radio properties independent of colour and \CIV distance.

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arXiv2023

EMU/GAMA: Radio detected galaxies are more obscured than optically selected galaxies

We demonstrate the importance of radio selection in probing heavily obscured galaxy populations. We combine Evolutionary Map of the Universe (EMU) Early Science data in the Galaxy and Mass Assembly (GAMA) G23 field with the GAMA data, providing optical photometry and spectral line measurements, together with Wide-field Infrared Survey Explorer (WISE) infrared (IR) photometry, providing IR luminosities and colours. We investigate the degree of obscuration in star forming galaxies, based on the Balmer decrement (BD), and explore how this trend varies, over a redshift range of 0<z<0.345. We demonstrate that the radio detected population has on average higher levels of obscuration than the parent optical sample, arising through missing the lowest BD and lowest mass galaxies, which are also the lower star formation rate (SFR) and metallicity systems. We discuss possible explanations for this result, including speculation around whether it might arise from steeper stellar initial mass functions in low mass, low SFR galaxies.

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arXiv2023

Ubiquitous radio emission in quasars: predominant AGN origin and a connection to jets, dust and winds

We present a comprehensive study of the physical origin of radio emission in optical quasars at redshifts z < 2.5. We focus particularly on the associations between compact radio emission, dust reddening, and outflows identified in our earlier work. Leveraging the deepest low-frequency radio data available to date (LoTSS Deep DR1), we achieve radio detection fractions of up to 94%, demonstrating the virtual ubiquity of radio emission in quasars, and a continuous distribution in radio loudness. Through our analysis of radio properties, combined with spectral energy distribution modeling of multiwavelength photometry, we establish that the primary source of radio emission in quasars is the AGN, rather than star formation. Modeling the dust reddening of the accretion disk emission shows a continuous increase in radio detection in quasars as a function of the reddening parameter E(B-V), suggesting a causal link between radio emission and dust reddening. Confirming previous findings, we observe that the radio excess in red quasars is most pronounced for sources with compact radio morphologies and intermediate radio loudness. We find a significant increase in [Oiii] and Civ outflow velocities for red quasars not seen in our control sample, with particularly powerful [Oiii] winds in those around the radio-quiet/radio-loud threshold. Based on the combined characterisation of radio, reddening, and wind properties in our sample, we favor a model in which the compact radio emission observed in quasars originates in compact radio jets and their interaction with a dusty, circumnuclear environment. Our results align with the theory that jet-induced winds and shocks resulting from this interaction are the origin of the enhanced radio emission in red quasars. Further investigation of this model is crucial for advancing our understanding of quasar feedback mechanisms and their role in galaxy evolution.

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arXiv2023

LOFAR HBA Observations of the Euclid Deep Field North (EDFN)

We present the first deep (72 hours of observations) radio image of the Euclid Deep Field North (EDFN) obtained with the LOw-Frequency ARray (LOFAR) High Band Antenna (HBA) at 144 MHz. The EDFN is the latest addition to the LOFAR Two-Metre Sky Survey (LoTSS) Deep Fields and these observations represent the first data release for this field. The observations produced a 6" resolution image with a central r.m.s. noise of $32\,μ$Jy\,beam$^{-1}$. A catalogue of $\sim 23,000$ radio sources above a signal-to-noise ratio (SNR) threshold of 5 is extracted from the inner circular 10 deg$^2$ region. We discuss the data analysis and we provide a detailed description of how we derived the catalogue of radio sources and on the issues related to direction-dependent calibration and their effects on the final products. Finally, we derive the radio source counts at 144 MHz in the EDFN using catalogues of mock radio sources to derive the completeness correction factors. The source counts in the EDFN are consistent with those obtained from the first data release of the other LoTSS Deep Fields (ELAIS-N1, Lockman Hole and Bootes), despite the different method adopted to construct the final catalogue and to assess its completeness.

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arXiv2023

The LOFAR Two-Metre Sky Survey (LoTSS): VI. Optical identifications for the second data release

The second data release of the LOFAR Two-Metre Sky Survey (LoTSS) covers 27% of the northern sky, with a total area of $\sim 5,700$ deg$^2$. The high angular resolution of LOFAR with Dutch baselines (6 arcsec) allows us to carry out optical identifications of a large fraction of the detected radio sources without further radio followup; however, the process is made more challenging by the many extended radio sources found in LOFAR images as a result of its excellent sensitivity to extended structure. In this paper we present source associations and identifications for sources in the second data release based on optical and near-infrared data, using a combination of a likelihood-ratio cross-match method developed for our first data release, our citizen science project Radio Galaxy Zoo: LOFAR, and new approaches to algorithmic optical identification, together with extensive visual inspection by astronomers. We also present spectroscopic or photometric redshifts for a large fraction of the optical identifications. In total 4,116,934 radio sources lie in the area with good optical data, of which 85% have an optical or infrared identification and 58% have a good redshift estimate. We demonstrate the quality of the dataset by comparing it with earlier optically identified radio surveys. This is by far the largest ever optically identified radio catalogue, and will permit robust statistical studies of star-forming and radio-loud active galaxies.

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arXiv2023

Cosmic evolution of radio-AGN feedback: confronting models with data

Radio-mode feedback is a key ingredient in galaxy formation and evolution models, required to reproduce the observed properties of massive galaxies in the local Universe. We study the cosmic evolution of radio-AGN feedback out to $z\sim2.5$ using a sample of 9485 radio-excess AGN. We combine the evolving radio luminosity functions with a radio luminosity scaling relationship to estimate AGN jet kinetic powers and derive the cosmic evolution of the kinetic luminosity density, $Ω_{\rm{kin}}$ (i.e. the volume-averaged heating output). Compared to all radio-AGN, low-excitation radio galaxies (LERGs) dominate the feedback activity out to $z\sim2.5$, with both these populations showing a constant heating output of $Ω_{\rm{kin}} \approx 4-5 \times 10^{32}\,\rm{W\,Mpc^{-3}}$ across $0.5 < z < 2.5$. We compare our observations to predictions from semi-analytical and hydrodynamical simulations, which broadly match the observed evolution in $Ω_{\rm{kin}}$, although their absolute normalisation varies. Comparison to the Semi-Analytic Galaxy Evolution (SAGE) model suggests that radio-AGN may provide sufficient heating to offset radiative cooling losses, providing evidence for a self-regulated AGN feedback cycle. We integrate the kinetic luminosity density across cosmic time to obtain the kinetic energy density output from AGN jets throughout cosmic history to be $\sim 10^{50}\,\rm{J\,Mpc^{-3}}$. Compared to AGN winds, the kinetic energy density from AGN jets dominates the energy budget at $z \lesssim 2$; this suggests that AGN jets play an important role in AGN feedback across most of cosmic history.

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arXiv2023

The LOFAR Two-metre Sky Survey: the radio view of the cosmic star formation history

We present a detailed study of the cosmic star formation history over $90$ per cent of cosmic time ($0\lesssim z\lesssim4$), using deep, radio continuum observations that probe star formation activity independent of dust. The Low Frequency Array Two Metre Sky Survey has imaged three well-studied extragalactic fields, Elais-N1, Boötes and the Lockman Hole, reaching $\sim20\,μ\rm{Jy/beam}$ rms sensitivity at $150\,\rm{MHz}$. The availability of high-quality ancillary data from ultraviolet to far-infrared wavelengths has enabled accurate photometric redshifts and the robust separation of radio-bright AGN from their star-forming counterparts. We capitalise on this unique combination of deep, wide fields and robustly-selected star-forming galaxies to construct radio luminosity functions and derive the cosmic star formation rate density. We carefully constrain and correct for scatter in the $L_{150\,\rm{MHz}}-\rm{SFR}$ relation, which we find to be $\sim0.3\,\rm{dex}$. Our derived star formation rate density lies between previous measurements at all redshifts studied. We derive higher star formation rate densities between $z\sim0$ and $z\sim3$ than are typically inferred from short wavelength emission; at earlier times, this discrepancy is reduced. Our measurements are generally in good agreement with far-infrared and radio-based studies, with small offsets resulting from differing star formation rate calibrations.

astro-ph.GA↗
arXiv2023

The LOFAR Two-metre Sky Survey Deep Fields Data Release 1: V. Survey description, source classifications and host galaxy properties

Source classifications, stellar masses and star formation rates are presented for 80,000 radio sources from the first data release of the Low Frequency Array Two-metre Sky Survey (LoTSS) Deep Fields, which represents the widest deep radio survey ever undertaken. Using deep multi-wavelength data spanning from the ultraviolet to the far-infrared, spectral energy distribution (SED) fitting is carried out for all of the LoTSS-Deep host galaxies using four different SED codes, two of which include modelling of the contributions from an active galactic nucleus (AGN). Comparing the results of the four codes, galaxies that host a radiative AGN are identified, and an optimised consensus estimate of the stellar mass and star-formation rate for each galaxy is derived. Those galaxies with an excess of radio emission over that expected from star formation are then identified, and the LoTSS-Deep sources are divided into four classes: star-forming galaxies, radio-quiet AGN, and radio-loud high-excitation and low-excitation AGN. Ninety-five per cent of the sources can be reliably classified, of which more than two-thirds are star-forming galaxies, ranging from normal galaxies in the nearby Universe to highly-starbursting systems at z>4. Star-forming galaxies become the dominant population below 150-MHz flux densities of about 1 mJy, accounting for 90 per cent of sources at a 150-MHz flux density of 100 microJy. Radio-quiet AGN comprise around 10 per cent of the overall population. Results are compared against the predictions of the SKADS and T-RECS radio sky simulations, and improvements to the simulations are suggested.

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arXiv2023

The AGN fuelling/feedback cycle in nearby radio galaxies - V. The cold atomic gas of NGC 3100 and its group

We present Australia Compact Telescope Array (ATCA) 21-cm observations of the nearby low-excitation radio galaxy (LERG) NGC 3100. This is the brightest galaxy of a loose group and hosts a young ($\sim 2$ Myr) radio source. The ATCA observations reveal for the first time the presence of neutral hydrogen (HI) gas in absorption in the centre of this radio galaxy, and in emission in two low-mass galaxies of the group and in a diffuse dark cloud in the proximity of NGC 3100. The sensitivity to low-column density gas ($N_{\rm HI}\sim 10^{19}$ cm$^{-2}$) allows us to reveal asymmetries in the periphery of most the HI-detected galaxies, suggesting that tidal interactions may be on-going. The diffuse cloud does not show a stellar counterpart down to $27$ mag/arcsec$^2$ and could be the remnant of these interactions. The analysis of the HI absorption complex in NGC 3100 indicates that the atomic phase of the hydrogen is distributed as its molecular phase (observed at arcsecond resolution through several carbon monoxide emission lines). We suggest that the interactions occurring within the group are causing turbulent cold gas clouds in the intra-group medium to be slowly accreted towards the centre of NGC 3100. This caused the recent formation of the cold circum-nuclear disk which is likely sustaining the young nuclear activity.

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arXiv2023

AGN feedback in an infant galaxy cluster: the LOFAR-Chandra view of the giant FRII radio galaxy J103025+052430 at z=1.7

In the nearby universe jets from AGN are observed to have a dramatic impact on their surrounding extragalactic environment. Their effect at the `cosmic noon' (z>1.5), the epoch when star formation and AGN activity peak, is instead much less constrained. Here we present a study of the giant (750 kpc) radio galaxy 103025+052430 located at the centre of a protocluster at redshift z=1.7, with a focus on its interaction with the external medium. We present new LOFAR observations at 144 MHz, which we combine with VLA 1.4 GHz and 0.5-7 keV Chandra archival data. The new map at 144 MHz confirms that the source has a complex morphology, possibly consistent with the `hybrid morphology' classification. The large size of the source gave us the possibility to perform a resolved radio spectral index analysis, a very unique opportunity for a source at such high redshift. This reveals a tentative flattening of the radio spectral index at the edge of the backflow in the Western lobe, which might be indicating plasma compression. The spatial coincidence between this region and the thermal X-ray bubble C suggests a causal connection between the two. Contrary to previous estimates for the bright X-ray component A, we find that inverse Compton scattering between the radio-emitting plasma of the Eastern lobe and the CMB photons can account for a large fraction (~45%-80%) of its total 0.5-7 keV measured flux. Finally, the X-ray bubble C, which is consistent with a thermal origin, is found to be significantly overpressurised with respect to the ambient medium. This suggests that it will tend to expand and release its energy in the surroundings, contributing to the overall intracluster medium heating. Overall, 103025+052430 gives us the chance to investigate the interaction between AGN jets and the surrounding gas in a system that is likely the predecessor of the rich galaxy clusters we all well know at z=0.

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arXiv2023

The LOFAR LBA Sky Survey II. First data release

The Low Frequency Array (LOFAR) is the only existing radio interferometer able to observe at ultra-low frequencies (<100 MHz) with high resolution (<15") and high sensitivity (<1 mJy/beam). To exploit these capabilities, the LOFAR Surveys Key Science Project is using the LOFAR Low Band Antenna (LBA) to carry out a sensitive wide-area survey at 41-66 MHz named the LOFAR LBA Sky Survey (LoLSS). LoLSS is covering the whole northern sky above declination 24 deg with a resolution of 15" and a sensitivity of 1-2 mJy/beam (1 sigma) depending on declination, field properties, and observing conditions. Here we present the first data release. An automated pipeline was used to reduce the 95 fields included in this data release. The data reduction procedures developed for this project have general application and are currently being used to process LOFAR LBA interferometric observations. Compared to the preliminary release, direction-dependent errors have been corrected for during the calibration process. This results in a typical sensitivity of 1.55 mJy/beam at the target resolution of 15". The first data release of the LOFAR LBA Sky Survey covers 650 sqdeg in the HETDEX spring field. The resultant data products released to the community include mosaic images (I and V Stokes) of the region, and a catalogue of 42463 detected sources and related Gaussian components used to describe sources' morphologies. Separate catalogues for 6 in-band frequencies are also released. The first data release of LoLSS shows that, despite the influences of the ionosphere, LOFAR can conduct large-scale surveys in the frequency window 42-66 MHz with unprecedentedly high sensitivity and resolution. The data can be used to derive unique information on the low-frequency spectral properties of many thousands of sources with a wide range of applications in extragalactic and galactic astronomy.

astro-ph.IM↗