| 11. |
- Pezzotta, A., et al.
(author)
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Euclid preparation XLI. Galaxy power spectrum modelling in real space
- 2024
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 687
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Journal article (peer-reviewed)abstract
- We investigate the accuracy of the perturbative galaxy bias expansion in view of the forthcoming analysis of the Euclid spectroscopic galaxy samples. We compare the performance of a Eulerian galaxy bias expansion using state-of-the-art prescriptions from the effective field theory of large-scale structure (EFTofLSS) with a hybrid approach based on Lagrangian perturbation theory and high-resolution simulations. These models are benchmarked against comoving snapshots of the flagship I N-body simulation at z = (0.9, 1.2, 1.5, 1.8), which have been populated with H alpha galaxies leading to catalogues of millions of objects within a volume of about 58 h(-3) Gpc(3). Our analysis suggests that both models can be used to provide a robust inference of the parameters (h, omega c) in the redshift range under consideration, with comparable constraining power. We additionally determine the range of validity of the EFTofLSS model in terms of scale cuts and model degrees of freedom. From these tests, it emerges that the standard third-order Eulerian bias expansion - which includes local and non-local bias parameters, a matter counter term, and a correction to the shot-noise contribution - can accurately describe the full shape of the real-space galaxy power spectrum up to the maximum wavenumber of k(max) = 0.45 h Mpc(-1), and with a measurement precision of well below the percentage level. Fixing either of the tidal bias parameters to physically motivated relations still leads to unbiased cosmological constraints, and helps in reducing the severity of projection effects due to the large dimensionality of the model. We finally show how we repeated our analysis assuming a volume that matches the expected footprint of Euclid, but without considering observational effects, such as purity and completeness, showing that we can get constraints on the combination (h, omega c) that are consistent with the fiducial values to better than the 68% confidence interval over this range of scales and redshifts.
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| 12. |
- Baldi, R. D., et al.
(author)
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LeMMINGs - II. The e-MERLIN legacy survey of nearby galaxies. The deepest radio view of the Palomar sample on parsec scale
- 2021
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In: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 500:4, s. 4749-4767
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Journal article (peer-reviewed)abstract
- We present the second data release of high-resolution (≤0.2 arcsec) 1.5-GHz radio images of 177 nearby galaxies from the Palomar sample, observed with the e-MERLIN array, as part of the Legacy e-MERLIN Multi-band Imaging of Nearby Galaxies Sample (LeMMINGs) survey. Together with the 103 targets of the first LeMMINGs data release, this represents a complete sample of 280 local active (LINER and Seyfert) and inactive galaxies (H ii galaxies and absorption line galaxies, ALG). This large program is the deepest radio survey of the local Universe, ≳1017.6 W Hz-1, regardless of the host and nuclear type: we detect radio emission ≳0.25 mJy beam-1 for 125/280 galaxies (44.6 per cent) with sizes of typically ≲100 pc. Of those 125, 106 targets show a core which coincides within 1.2 arcsec with the optical nucleus. Although we observed mostly cores, around one third of the detected galaxies features jetted morphologies. The detected radio core luminosities of the sample range between ∼1034 and 1040 erg s-1. LINERs and Seyferts are the most luminous sources, whereas H ii galaxies are the least. LINERs show FR I-like core-brightened radio structures while Seyferts reveal the highest fraction of symmetric morphologies. The majority of H ii galaxies have single radio core or complex extended structures, which probably conceal a nuclear starburst and/or a weak active nucleus (seven of them show clear jets). ALGs, which are typically found in evolved ellipticals, although the least numerous, exhibit on average the most luminous radio structures, similar to LINERs.
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| 13. |
- Baldi, R. D., et al.
(author)
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LeMMINGs III. The e-MERLIN legacy survey of the Palomar sample: Exploring the origin of nuclear radio emission in active and inactive galaxies through the [O iii] - Radio connection
- 2021
-
In: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 508:2, s. 2019-2038
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Journal article (peer-reviewed)abstract
- What determines the nuclear radio emission in local galaxies? To address this question, we combine optical [O iii] line emission, robust black hole (BH) mass estimates, and high-resolution e-MERLIN 1.5-GHz data, from the LeMMINGs survey, of a statistically complete sample of 280 nearby optically active (LINER and Seyfert) and inactive [H ii and absorption line galaxies (ALGs)] galaxies. Using [O iii] luminosity (L[O III]) as a proxy for the accretion power, local galaxies follow distinct sequences in the optical-radio planes of BH activity, which suggest different origins of the nuclear radio emission for the optical classes. The 1.5-GHz radio luminosity of their parsec-scale cores (Lcore) is found to scale with BH mass (MBH) and [O iii] luminosity. Below MBH ∼106.5 M⊙, stellar processes from non-jetted H ii galaxies dominate with Lcore ∝ MBH0.61 ± 0.33 and Lcore ∝ L[O III]0.79 ± 0.30. Above MBH ∼106.5 M⊙, accretion-driven processes dominate with Lcore ∝ MBH1.5-1.65 and Lcore ∝ L[O III]0.99-1.31 for active galaxies: radio-quiet/loud LINERs, Seyferts, and jetted H ii galaxies always display (although low) signatures of radio-emitting BH activity, with L1.5 GHz ≳ 1019.8 W Hz-1 and MBH ≳ 107 M⊙, on a broad range of Eddington-scaled accretion rates (m). Radio-quiet and radio-loud LINERs are powered by low-m discs launching sub-relativistic and relativistic jets, respectively. Low-power slow jets and disc/corona winds from moderately high to high-m discs account for the compact and edge-brightened jets of Seyferts, respectively. Jetted H ii galaxies may host weakly active BHs. Fuel-starved BHs and recurrent activity account for ALG properties. In conclusion, specific accretion-ejection states of active BHs determine the radio production and the optical classification of local active galaxies.
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| 14. |
- Contarini, S., et al.
(author)
-
Euclid : cosmological forecasts from the void size function
- 2022
-
In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 667
-
Journal article (peer-reviewed)abstract
- The Euclid mission - with its spectroscopic galaxy survey covering a sky area over 15 000 deg(2) in the redshift range 0.9 < z < 1.8 - will provide a sample of tens of thousands of cosmic voids. This paper thoroughly explores for the first time the constraining power of the void size function on the properties of dark energy (DE) from a survey mock catalogue, the official Euclid Flagship simulation. We identified voids in the Flagship light-cone, which closely matches the features of the upcoming Euclid spectroscopic data set. We modelled the void size function considering a state-of-the art methodology: we relied on the volume-conserving (Vdn) model, a modification of the popular Sheth & van de Weygaert model for void number counts, extended by means of a linear function of the large-scale galaxy bias. We found an excellent agreement between model predictions and measured mock void number counts. We computed updated forecasts for the Euclid mission on DE from the void size function and provided reliable void number estimates to serve as a basis for further forecasts of cosmological applications using voids. We analysed two different cosmological models for DE: the first described by a constant DE equation of state parameter, w, and the second by a dynamic equation of state with coefficients w(0) and w(a). We forecast 1 sigma errors on w lower than 10% and we estimated an expected figure of merit (FoM) for the dynamical DE scenario FoM(w0,wa) = 17 when considering only the neutrino mass as additional free parameter of the model. The analysis is based on conservative assumptions to ensure full robustness, and is a pathfinder for future enhancements of the technique. Our results showcase the impressive constraining power of the void size function from the Euclid spectroscopic sample, both as a stand-alone probe, and to be combined with other Euclid cosmological probes.
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| 15. |
- Dullo, B. T., et al.
(author)
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LeMMINGs. Multiwavelength constraints on the co-existence of nuclear star clusters and AGN in nucleated galaxies
- 2024
-
In: Monthly Notices of the Royal Astronomical Society. - 0035-8711 .- 1365-2966. ; 532:4, s. 4729-4751
-
Journal article (peer-reviewed)abstract
- The relation between nuclear star clusters (NSCs) and the growth of the central supermassive black holes (SMBHs), as well as their connection to the properties of the host galaxies, is crucial for understanding the evolution of galaxies. Recent observations have revealed that about 10 per cent of nucleated galaxies host hybrid nuclei, consisting of both NSCs and accreting SMBHs that power active galactic nuclei (AGNs). Motivated by the potential of the recently published multiwavelength data sets from LeMMINGs survey, here we present the most thorough investigation to date of the incidence of hybrid nuclei in a large sample of 100 nearby nucleated galaxies (10 E, 25 S0, 63 S, and 2 Irr), covering a wide range in stellar mass (M∗,gal ∼ 108.7 - 1012 M☉). We identify the nuclei and derive their properties by performing detailed 1D and 2D multicomponent decompositions of the optical and near-infrared HST stellar light distributions of the galaxies using Sérsic and core-Sérsic models. Our AGN diagnostics are based on homogeneously derived nuclear 1.5 GHz e-MERLIN radio, Chandra X-ray (0.3–10 keV), and optical emission-line data. We determine the nucleation fraction (fnuc) as the relative incidence of nuclei across the LeMMINGs HST sample and find fnuc = 100/149 (= 67 ± 7 per cent), confirming previous work, with a peak value of 49/56 (= 88 ± 13 per cent) at bulge masses M∗,bulge ∼ 109.4 - 1010.8 M☉. We identify 30 nucleated LeMMINGs galaxies that are optically active, radio-detected, and X-ray luminous (LX > 1039 erg s-1). This indicates that our nucleated sample has a lower limit ∼ 30 per cent occupancy of hybrid nuclei, which is a function of M∗,bulge and M∗,gal. We find that hybrid nuclei have a number density of (1.5 ± 0.4) × 10-5 Mpc-3, are more common at M∗,gal ∼ 1010.6 - 1011.8 M☉ and occur, at least, three times more frequently than previously reported.
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| 16. |
- Dullo, B. T., et al.
(author)
-
LeMMINGs. VI. Connecting nuclear activity to bulge properties of active and inactive galaxies: radio scaling relations and galaxy environment
- 2023
-
In: Monthly Notices of the Royal Astronomical Society. - 0035-8711 .- 1365-2966. ; 522:3, s. 3412-3438
-
Journal article (peer-reviewed)abstract
- Multiwavelength studies indicate that nuclear activity and bulge properties are closely related, but the details remain unclear. To study this further, we combine Hubble Space Telescope bulge structural and photometric properties with 1.5 GHz, e-MERLIN nuclear radio continuum data from the LeMMINGs survey for a large sample of 173 'active' galaxies (LINERs and Seyferts) and 'inactive' galaxies (H IIs and absorption line galaxies, ALGs). Dividing our sample into active and inactive, they define distinct (radio core luminosity)-(bulge mass), LR,core − M∗,bulge, relations, with a mass turnover at M∗,bulge ∼ 109.8±0.3M☉ (supermassive blackhole mass MBH ∼ 106.8±0.3M☉), which marks the transition from AGN-dominated nuclear radio emission in more massive bulges to that mainly driven by stellar processes in low-mass bulges. None of our 10/173 bulge-less galaxies host an AGN. The AGN fraction increases with increasing M∗,bulge such that foptical_AGN ∝ M∗,bulge0.24±0.06 and fradio_AGN ∝ M∗,bulge0.24±0.05. Between M∗,bulge ∼ 108.5 and 1011.3M☉, foptical_AGN steadily rises from 15 ± 4 to 80 ± 5 per cent. We find that at fixed bulge mass, the radio loudness, nuclear radio activity, and the (optical and radio) AGN fraction exhibit no dependence on environment. Radio-loud hosts preferentially possess an early-type morphology than radio-quiet hosts, the two types are however indistinguishable in terms of bulge Sérsic index and ellipticity, while results on the bulge inner logarithmic profile slope are inconclusive. We finally discuss the importance of bulge mass in determining the AGN triggering processes, including potential implications for the nuclear radio emission in nearby galaxies.
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| 17. |
- Hamaus, N., et al.
(author)
-
Euclid : Forecasts from redshift-space distortions and the Alcock-Paczynski test with cosmic voids
- 2022
-
In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 658
-
Journal article (peer-reviewed)abstract
- Euclid is poised to survey galaxies across a cosmological volume of unprecedented size, providing observations of more than a billion objects distributed over a third of the full sky. Approximately 20 million of these galaxies will have their spectroscopy available, allowing us to map the three-dimensional large-scale structure of the Universe in great detail. This paper investigates prospects for the detection of cosmic voids therein and the unique benefit they provide for cosmological studies. In particular, we study the imprints of dynamic (redshift-space) and geometric (Alcock-Paczynski) distortions of average void shapes and their constraining power on the growth of structure and cosmological distance ratios. To this end, we made use of the Flagship mock catalog, a state-of-the-art simulation of the data expected to be observed with Euclid. We arranged the data into four adjacent redshift bins, each of which contains about 11000 voids and we estimated the stacked void-galaxy cross-correlation function in every bin. Fitting a linear-theory model to the data, we obtained constraints on f/b and DMH, where f is the linear growth rate of density fluctuations, b the galaxy bias, D-M the comoving angular diameter distance, and H the Hubble rate. In addition, we marginalized over two nuisance parameters included in our model to account for unknown systematic effects in the analysis. With this approach, Euclid will be able to reach a relative precision of about 4% on measurements of f/b and 0.5% on DMH in each redshift bin. Better modeling or calibration of the nuisance parameters may further increase this precision to 1% and 0.4%, respectively. Our results show that the exploitation of cosmic voids in Euclid will provide competitive constraints on cosmology even as a stand-alone probe. For example, the equation-of-state parameter, w, for dark energy will be measured with a precision of about 10%, consistent with previous more approximate forecasts.
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| 18. |
- Pöntinen, M., et al.
(author)
-
Euclid: Identification of asteroid streaks in simulated images using deep learning
- 2023
-
In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 679
-
Journal article (peer-reviewed)abstract
- The material composition of asteroids is an essential piece of knowledge in the quest to understand the formation and evolution of the Solar System. Visual to near-infrared spectra or multiband photometry is required to constrain the material composition of asteroids, but we currently have such data, especially in the near-infrared wavelengths, for only a limited number of asteroids. This is a significant limitation considering the complex orbital structures of the asteroid populations. Up to 150 000 asteroids will be visible in the images of the upcoming ESA Euclid space telescope, and the instruments of Euclid will offer multiband visual to near-infrared photometry and slitless near-infrared spectra of these objects. Most of the asteroids will appear as streaks in the images. Due to the large number of images and asteroids, automated detection methods are needed. A non-machine-learning approach based on the Streak Det software was previously tested, but the results were not optimal for short and/or faint streaks. We set out to improve the capability to detect asteroid streaks in Euclid images by using deep learning. We built, trained, and tested a three-step machine-learning pipeline with simulated Euclid images. First, a convolutional neural network (CNN) detected streaks and their coordinates in full images, aiming to maximize the completeness (recall) of detections. Then, a recurrent neural network (RNN) merged snippets of long streaks detected in several parts by the CNN. Lastly, gradient-boosted trees (XGBoost) linked detected streaks between different Euclid exposures to reduce the number of false positives and improve the purity (precision) of the sample. The deep-learning pipeline surpasses the completeness and reaches a similar level of purity of a non-machine-learning pipeline based on the StreakDet software. Additionally, the deep-learning pipeline can detect asteroids 0.25–0.5 magnitudes fainter than StreakDet. The deep-learning pipeline could result in a 50% increase in the number of detected asteroids compared to the StreakDet software. There is still scope for further refinement, particularly in improving the accuracy of streak coordinates and enhancing the completeness of the final stage of the pipeline, which involves linking detections across multiple exposures.
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| 19. |
- Williams, D. R.A., et al.
(author)
-
LeMMINGs - IV. The X-ray properties of a statistically complete sample of the nuclei in active and inactive galaxies from the Palomar sample
- 2022
-
In: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 510:4, s. 4909-4928
-
Journal article (peer-reviewed)abstract
- All 280 of the statistically complete Palomar sample of nearby ( < 120 Mpc) galaxies δ> 20 ◦have been observed at 1.5 GHz as part of the LeMMINGs e -MERLIN le gac y surv e y. Here, we present Chandr a X-ray observations of the nuclei of 213 of these galaxies, including a statistically complete sub-set of 113 galaxies in the declination range 40 ◦<δ< 65 ◦. We observed galaxies of all optical spectral types, including 'active' galaxies [e.g. low-ionization nuclear emission line regions (LINERs) and Seyferts] and 'inactive' galaxies like H II galaxies and absorption line galaxies (ALG). The X-ray flux limit of our surv e y is 1.65 ×10 -14 erg s -1 cm -2 (0.3 -10 keV). We detect X-ray emission coincident within 2 arcsec of the nucleus in 150/213 galaxies, including 13/14 Seyferts, 68/77 LINERs, 13/22 ALGs and 56/100 H II galaxies, but cannot completely rule out contamination from non-AGN processes in sources with nuclear luminosities ≲ 10 39 erg s -1 . We construct an X-ray Luminosity function (XLF) and find that the local galaxy XLF, when including all active galactic nucleus (AGN) types, can be represented as a single power law of slope -0.54 ±0.06. The Eddington ratio of the Seyferts is usually 2 -4 decades higher than that of the LINERs, ALGs, and H II galaxies, which are mostly detected with Eddington ratios ≲ 10 -3 . Using [ O III ] line measurements and black hole masses from the literature, we show that LINERs, H II galaxies and ALGs follow similar correlations to low luminosities, suggesting that some 'inactive' galaxies may harbour AGN.
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| 20. |
- Dullo, B. T., et al.
(author)
-
LeMMINGs: V. Nuclear activity and bulge properties: A detailed multi-component decomposition of e -MERLIN Palomar galaxies with HST
- 2023
-
In: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 675
-
Journal article (peer-reviewed)abstract
- We used high-resolution HST imaging and e-MERLIN 1.5-GHz observations of galaxy cores from the LeMMINGs survey to investigate the relation between optical structural properties and nuclear radio emission for a large sample of galaxies. We performed accurate, multi-component decompositions of new surface brightness profiles extracted from HST images for 163 LeMMINGs galaxies and fitted up to six galaxy components (e.g. bulges, discs, AGN, bars, rings, spiral arms, and nuclear star clusters) simultaneously with Sérsic and/or core-Sérsic models. By adding such decomposition data for ten LeMMINGs galaxies from our past work, the final sample of 173 nearby galaxies (102 Ss, 42 S0s, 23 Es, plus six Irr) with a typical bulge stellar mass of M∗,bulge ~ 106 -1012.5 M⊙ encompasses all optical spectral classes: low-ionisation nuclear emission-line region (LINER), Seyfert, Absorption Line Galaxy (ALG), and H′ ¯II. We show that the bulge mass can be significantly overestimated in many galaxies when components such as bars, rings, and spirals are not included in the fits. We additionally implemented a Monte Carlo method to determine errors on the bulge, disc, and other fitted structural parameters. Moving (in the opposite direction) across the Hubble sequence, that is from the irregular to elliptical galaxies, we confirm that bulges become larger, more prominent, and round. Such bulge dominance is associated with a brighter radio core luminosity. We also find that the radio detection fraction increases with bulge mass. At M∗,bulge ≫ 1011 M⊙, the radio detection fraction is 77%, declining to 24% for M∗,bulge < 1010 M⊙. Furthermore, we observe that core-Sérsic bulges tend to be systematically round and to possess high radio core luminosities and boxy-distorted or pure elliptical isophotes. However, there is no evidence for the previously alleged strong tendency of galaxies'central structures (i.e. a sharp Sérsic, core-Sérsic dichotomy) with their radio loudness, isophote shape, and flattening.
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