3 citations · 5 across the 13 of their papers we have counts for
13 papers
A new Chandra look at the globular cluster NGC 6540 and its peculiar X-ray flaring source
A. Sacchi, S. Mereghetti, R. Di Stefano +4
We report the results of a deep ( ks) Chandra exposure of the globular cluster NGC 6540, obtained by combining three observations carried out in 2023-2024 to investigate…
The X-ray-to-UV relation does not evolve in homogeneous quasar samples
G. Risaliti, E. Lusso, E. Nardini +6
We present a new, highly homogeneous quasar sample with X-ray and UV observations optimized to reliably estimate distances via the non-linear X-ray-to-UV relation. Cross-matching t…
A supermassive black hole under the radar: Repeating X-ray variability in a Seyfert galaxy
Matteo Imbrogno, Andrea Sacchi, Giovanni Miniutti +4
In the last few years, a few supermassive black holes (SMBHs) have shown short-term (of the order of hours) X-ray variability. Given the limited size of the sample, every new addit…
Chandra Rules Out Super-Eddington Accretion Models For Little Red Dots
Andrea Sacchi, Akos Bogdan
One of the most puzzling discoveries by JWST is the population of high-redshift, red, and compact galaxies dubbed little red dots (LRDs). Based on broad-line diagnostics, these gal…
Probing the interstellar medium toward GRB 221009A through X-ray dust scattering
B. Vaia, Ž. Bošnjak, A. Bracco +5
The observation of 21 X-ray dust-scattering rings around the extraordinarily bright gamma-ray burst (GRB) 221009A provides a unique opportunity to study the interstellar medium (IS…
Hyperluminous Supersoft X-Ray Sources in the Chandra Catalog
Andrea Sacchi, Kevin Paggeot, Steven Dillmann +2
Hyperluminous supersoft X-ray sources, such as bright extragalactic sources characterized by particularly soft X-ray spectra, offer a unique opportunity to study accretion onto sup…
Detection of Anisotropies in the Circumgalactic Medium of Disk Galaxies: Supermassive Black Hole Activity or Star Formation-driven Outflows?
Andrea Sacchi, Akos Bogdan, Nhut Truong
Gamma and X-ray observatories have revealed spectacular structures in the emission of the tenuous hot gas surrounding the Milky Way (MW), known as the Fermi and eROSITA bubbles. Ga…
The impact of periastron passage on the X-ray and optical properties of the Symbiotic System R Aquarii
D. A. Vásquez-Torres, J. A. Toalá, A. Sacchi +4
Multi-epoch Chandra and XMM-Newton observations of the symbiotic system R Aquarii (R Aqr) spanning 22 yr are analysed by means of a reflection model produced by an accretion disc.…
The restless population of bright X-ray sources of NCG 3621
A. Sacchi, M. Imbrogno, S. E. Motta +9
We report on the multi-year evolution of the population of X-ray sources in the nuclear region of NGC 3621 based on Chandra, XMM-Newton and Swift observations. Among these, two sou…
The X-ray rise and fall of the Recurrent Symbiotic System T CrB
Jesús A. Toalá, Omaira González-Martín, Andrea Sacchi +1
We present the analysis of publicly available NuSTAR, Suzaku and XMM-Newton observations of the symbiotic recurrent nova T CrB covering the 2006.77-2022.66 yr period. The X-ray spe…
Detection of a Highly Ionized Outflow in the Quasi-periodically Erupting Source GSN 069
P. Kosec, E. Kara, L. Brenneman +8
Quasi-periodic eruptions (QPEs) are high-amplitude, soft X-ray bursts recurring every few hours, associated with supermassive black holes. Many interpretations for QPEs were propos…
Front-row seat of the recent R Aqr periastron passage: X-ray multi-epoch spectral and spatial analysis
A. Sacchi, M. Karovska, J. Raymond +7
We report on the X-ray spectral and spatial evolution of the Symbiotic star R Aqr. Through a multi-epoch observational campaign performed with Chandra between 2017 and 2022, we stu…
A soft and transient ultraluminous X-ray source with 6-h modulation in the NGC 300 galaxy
A. Sacchi, P. Esposito, D. de Martino +13
We investigate the nature of CXOU J005440.5-374320 (J0054), a peculiar bright ( erg/s) and soft X-ray transient in the spiral galaxy NGC 300 with a 6-hour per…