A5077019669- Astrophysical Phenomena and Observations
- Galaxies: Formation, Evolution, Phenomena
- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Astronomy and Astrophysical Research
- Radio Astronomy Observations and Technology
- Astronomical Observations and Instrumentation
- Solar and Space Plasma Dynamics
- Pulsars and Gravitational Waves Research
- Adaptive optics and wavefront sensing
- Advanced Measurement and Metrology Techniques
- Stellar, planetary, and galactic studies
Osservatorio Astronomico di Padova
2018-2024
University of Padua
2018-2024
We considered the fourth catalog of gamma-ray point sources produced by Fermi Large Area Telescope (LAT) and selected only jetted active galactic nuclei (AGN) or with no specific classification, but a low-frequency counterpart. Our final list is composed 2980 sources. then searched for optical spectra in all available literature publicly databases, to measure redshifts confirm change original LAT classification. emitting AGN BL Lac Objects (40%), flat-spectrum radio quasars (23%), misaligned...
In the last decade of Active Galactic Nuclei (AGN) monitoring programs, Mets\"ahovi Radio Observatory detected multiple times seven powerful flaring narrow-line Seyfert 1 (NLS1) galaxies at 37 GHz. Several hypotheses have been proposed, but understanding this unique phenomenon is still far. To look case from a different point view, we performed an emission line analysis optical spectra, with aim identifying similarities among sources, that can be in turn possibly tied radio behavior. Our...
Over the last decade of active galactic nucleus (AGN) monitoring programs, Metsähovi Radio Observatory has made multiple detections seven powerful flaring narrow-line Seyfert 1 (NLS1) galaxies at 37 GHz. Several hypotheses have been proposed, but understanding this unique phenomenon is still far away. To look case from a different point view, we performed an emission line analysis optical spectra, with aim identifying similarities among sources, which in turn can possibly be tied radio...
Narrow-line Seyfert 1 (NLS1) galaxies are peculiar active galactic nuclei. Most of them do not show strong radio emission, but seven radio-quiet (or radio-silent) NLS1s have recently been detected flaring multiple times at 37 GHz by the Metsähovi Radio Telescope, indicating relativistic jets in these sources. We observed with Karl G. Jansky Very Large Array (JVLA) A configuration 1.6, 5.2, and 9.0 GHz. Our results that sources either extremely faint or JVLA bands. At frequencies, emission...
Abstract We present new 1.5–8.5 GHz Very Long Baseline Array (VLBA) observations and 0.32–1.26 Giant Meterwave Radio Telescope (GMRT) of J0354−1340, which is the only known radio-quiet (RQ) or radio-intermediate (RI) narrow-line Seyfert 1 galaxy with a 100 kpc, two-sided radio jet. A parsec-scale, one-sided jet in southeastern direction from core emission found VLBA observations, while kiloparsec-scale observed Karl G. Jansky Large (VLA) GMRT south–north direction. Core spectra on parsec...
We present the results of new radio observations carried out with Karl G. Jansky Very Large Array C-configuration at 5.5 GHz for a sample southern narrow-line Seyfert 1 galaxies (NLS1s). This work increases number known radio-detected NLS1s in hemisphere, and confirms that emission is mainly concentrated central region kpc-scale only few sources show diffuse emission. In radio-quiet NLS1s, luminosity tends to be higher steep-spectrum lower flat-spectrum sources, which opposite radio-loud...
Narrow-line Seyfert 1 (NLS1) galaxies are a peculiar sub-class of active galactic nuclei (AGNe). They have demonstrated that the presence relativistic jets in an AGN is not strictly related to its radio-loudness, black hole mass, or their host galaxy type. Here, we present remarkable example radio-quiet NLS1, 6dFGS gJ035432.8−134008 (J0354−1340). In our Karl G. Jansky Very Large Array observations at 5.5 GHz, source shows bright core with flat spectral index and extended emission...
Narrow-line Seyfert 1 (NLS1) galaxies are a class of active galactic nuclei (AGN) that, in some cases, can harbor powerful relativistic jets. One them, PKS 2004-447, shows gamma-ray emission, and underwent its first recorded multifrequency flare 2019. However, past studies revealed that radio this source be classified as compact steep-spectrum (CSS), suggesting unlike other sources, the jets 2004-447 have large inclination with respect to line sight. We present here set spectroscopic...
The term ‘active galactic nuclei’ (AGN) is applied to a huge variety of objects, classified on the basis their properties at different wavelengths. Peaked sources (PSs) represent class AGN first stage evolution, characterised by peaked radio spectrum. Among these sources, low-luminosity compact (LLC) can be identified as PSs accreting with high Eddington rate, harbouring low-power jets, and hosting low-mass black holes. These are also shared narrow-line Seyfert 1 galaxies (NLS1s). In 2016,...
In this paper, we present the analysis of new radio and optical observations narrow-line Seyfert 1 galaxy Mrk 783. 1.6 GHz performed with e-MERLIN interferometer confirm presence diffuse emission previously observed. The Very Long Baseline Array (VLBA) also detects nuclear source both at (L-Band) 5 (C-band). While L-band image shows only an unresolved core, C-band a partially resolved structure, position angle 60{\deg}. brightness temperature in bands ($>10^6$ K) suggests that it is pc-scale...
We present first results of the analysis optical spectra two complementary samples Seyfert galaxies (Seyferts). The sample was extracted from a selection 4th Fermi Gamma-ray Large Area Telescope (4FGL) catalog and consists 11 γ-ray-emitting jetted galaxies. second one Swift-BAT AGN Spectroscopic Survey (BASS) is composed 38 hard-X-ray-selected active galactic nuclei (AGN). These are complementary, with former being expected to have smaller viewing angles, while latter may include objects...
We present the X-ray spectral analysis of two complementary sets intermediate Seyfert galaxies (ISs). Analyzing data, we estimate hydrogen abundance $N_H$ and test its connection with [O III] luminosity acquired from optical observations. The results confirm conclusions drawn in a previous study concerning lack direct correlation between obscuration measure ($N_H$) intrinsic characteristics active nuclei ([O luminosity). Instead, validate existence type parameter, employing separation...
The term 'active galactic nuclei' (AGN) subtends a huge variety of objects, classified on their properties at different wavelengths. Peaked sources (PS) represent class AGN the first stage evolution, characterised by peaked radio spectrum. Among these sources, low-luminosity compact (LLC) can be identified as PS accreting with high Eddington rate, harbouring low-power jets and hosting low-mass black holes. These are also shared narrow-line Seyfert 1 galaxies (NLS1s). In 2016, LLCs were...
Narrow-line Seyfert 1 galaxies (NLS1s) are a subclass of active galactic nuclei (AGN). It is often believed that these AGN have small black hole mass, which responsible for the narrowness permitted lines. They also characterised by high accretion rate, typically closer to Eddington limit. Nevertheless, narrow lines might be caused disk-like broad-line region (BLR) viewed pole-on. This class objects presents strong X-ray emission, very steep spectral index described single power law. In...
Narrow-line Seyfert 1 galaxies (NLS1s) are a subclass of active galactic nuclei (AGN). It is often believed that these AGN have small black hole mass, which responsible for the narrowness permitted lines. They also characterised by high accretion rate, typically closer to Eddington limit. Nevertheless, narrow lines might be caused disk-like broad-line region (BLR) viewed pole-on. This class objects presents strong X-ray emission, very steep spectral index described single power law. In...
We present preliminary results of the analysis optical spectra two complementary samples Seyfert galaxies. The first sample was extracted from a selection 4th Fermi Gamma-ray Large Area Telescope (4FGL) catalog, and consists 9 $\gamma$-ray emitting jetted second one Swift-BAT AGN Spectroscopic Survey (BASS), is composed 38 hard-X ray selected Active Galactic Nuclei (AGN). These are complementary, with former expected to have smaller viewing angles, while latter may include objects larger...
We present new 1.5-8.5 GHz Very Long Baseline Array (VLBA) observations and 0.32-1.26 Giant Meterwave Radio Telescope (GMRT) of J0354-1340, which is the only known radio-quiet (RQ) or radio-intermediate (RI) narrow-line Seyfert 1 galaxy with a 100-kpc two-sided radio jet. A pc-scale one-sided jet in southeast direction from core emission found VLBA observations, while kpc-scale observed Karl G. Jansky Large (VLA) GMRT south-north direction. The spectra on pc kpc scales are presented...
Properties of the broad line region (BLR) in active galactic nuclei (AGNs) are commonly used to estimate mass supermassive black hole (SMBH) that powers an AGN. However, understanding physics behind BLR remains incomplete. The AGNs exhibit strong optical variability, observed change profiles and fluxes emission lines. Utilizing this variability provides opportunity constrain BLR, understand interplay with SMBH surrounding regions. Here, we present long-term monitoring campaign a sample known...
We present a detailed study of 11 narrow-line Seyfert 1 galaxies (NLS1s) from the Six-degree Field Galaxy Survey (6dFGS) that both have optical and X-ray spectroscopic observations. There are five complex NLS1s (C-NLS1s) six simple (S-NLS1s). propose possible correlation between [O III] line asymmetry complexity. The outflow or wind inner accretion disk is commonly in mostly directed along system axis. In C-NLS1s only weak effects measured, spectral complexity might be caused by presence...