R. Arcodia
A5040626561- Astrophysical Phenomena and Observations
- Galaxies: Formation, Evolution, Phenomena
- Gamma-ray bursts and supernovae
- Astrophysics and Cosmic Phenomena
- Astronomy and Astrophysical Research
- Pulsars and Gravitational Waves Research
- Astronomical Observations and Instrumentation
- Mechanics and Biomechanics Studies
- Stellar, planetary, and galactic studies
- Radio Astronomy Observations and Technology
- Cosmology and Gravitation Theories
- High-pressure geophysics and materials
- Dark Matter and Cosmic Phenomena
- Solar and Space Plasma Dynamics
- Fluid Dynamics and Turbulent Flows
- Particle accelerators and beam dynamics
- Statistics Education and Methodologies
- Black Holes and Theoretical Physics
- Geophysics and Gravity Measurements
- X-ray Spectroscopy and Fluorescence Analysis
- Relativity and Gravitational Theory
- Methane Hydrates and Related Phenomena
- Structural Health Monitoring Techniques
- Particle Detector Development and Performance
- SAS software applications and methods
Massachusetts Institute of Technology
2023-2025
Center for Astrophysics Harvard & Smithsonian
2025
Kavli Institute for Particle Astrophysics and Cosmology
2025
Max Planck Institute for Extraterrestrial Physics
2018-2024
Vassar College
2023-2024
University of Milano-Bicocca
2016-2018
Brera Astronomical Observatory
2016-2018
This paper documents the sixteenth data release (DR16) from Sloan Digital Sky Surveys; fourth and penultimate phase (SDSS-IV). is first of southern hemisphere survey Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2); new APOGEE-2 North are also included. DR16 notable as final for main cosmological program Extended Baryon Oscillation Spectroscopic Survey (eBOSS), all raw reduced spectra that project released here. includes Time Domain (TDSS) SPectroscopic IDentification...
The eROSITA telescope array aboard the Spektrum Roentgen Gamma (SRG) satellite began surveying sky in December 2019, with aim of producing all-sky X-ray source lists and maps an unprecedented depth. Here we present catalogues both point-like extended sources using data acquired first six months survey operations (eRASS1; completed June 2020) over half whose proprietary rights lie German Consortium. We describe observation process, analysis pipelines, characteristics sources. With nearly 930...
Context. In November 2019, eROSITA on board of the Spektrum-Roentgen-Gamma (SRG) observatory started to map entire sky in X-rays. After four-year survey program, it will reach a flux limit that is about 25 times deeper than ROSAT. During SRG performance verification phase, observed contiguous 140 deg 2 area down final depth all-sky (eROSITA Final Equatorial-Depth Survey; eFEDS), with goal obtaining census X-ray emitting populations (stars, compact objects, galaxies, clusters and active...
Stars that interact with supermassive black holes (SMBHs) can either be completely or partially destroyed by tides. In a partial tidal disruption event (TDE) the high-density core of star remains intact, and low-density, outer envelope is stripped feeds luminous accretion episode. The TDE AT2018fyk, an inferred hole mass $10^{7.7\pm0.4}$ M$_{\odot}$, experienced extreme dimming at X-ray (factor $>$6000) UV $\sim$15) wavelengths $\sim$500--600 days after discovery. Here we report on...
X-ray quasi-periodic eruptions (QPEs) represent a recently discovered example of extreme variability associated with supermassive black holes. These are high-amplitude bursts recurring every few hours that detected in the soft band from nuclei nearby galaxies whose optical spectra lack broad emission lines typically observed unobscured active galaxies. The physical origin this new phenomenon is still unknown and several theoretical models have been presented. However, no attempt has made so...
X-ray quasi-periodic eruptions (QPEs) are a novel addition to the group of extragalactic transients. With only select number known sources, and many more models published trying explain them, we so far limited in our understanding by small statistics. In this work, report discovery two further galaxies showing QPEs, hereafter named eRO-QPE3 eRO-QPE4, with eROSITA telescope on board Spectrum Roentgen Gamma observatory, followed XMM-Newton , NICER, Swift -XRT, SALT ( z = 0.024 0.044,...
Abstract The Lunar Gravitational-wave Antenna (LGWA) is a proposed array of next-generation inertial sensors to monitor the response Moon gravitational waves (GWs). Given size and expected noise produced by lunar seismic background, LGWA would be able observe GWs from about 1 mHz Hz. This make missing link between space-borne detectors like LISA with peak sensitivities around few millihertz future terrestrial Einstein Telescope or Cosmic Explorer. In this article, we provide first...
Abstract Quasi-periodic eruptions (QPEs) are a recently identified class of X-ray transient associated with tidal disruption events by supermassive black holes, and for which there multiple possible explanations. In this paper we present simple model requires the hole be spinning, misaligned accretion flow (both conditions almost certainly met) that rate is few times Eddington limit. We speculate resulting Lense-Thirring torques force disc entrained outflows to precess, leading increased...
Context: After the successful launch of Spectrum-Roentgen-Gamma (SRG) mission in July 2019, eROSITA, soft X-ray instrument aboard SRG, performed scanning observations a large contiguous field, namely eROSITA Final Equatorial Depth Survey (eFEDS), ahead planned four-year all-sky survey. eFEDS yielded sample sources with very rich multi-band photometric and spectroscopic coverage. Aims: We present here Active Galactic Nuclei (AGN) catalog spectral properties sources. Methods: Using Bayesian...
GSN 069 is the first galactic nucleus where quasi-periodic eruptions (QPEs) have been identified. These are high-amplitude, soft X-ray bursts recurring every ~9 hr, lasting ~1 and during which count rate increases by up to two orders of magnitude with respect an otherwise stable quiescent level. The spectral properties long-term evolution in few years consistent a long-lived tidal disruption event (TDE). Here we derive QPEs over past 12 yr studying timing data from 11 XMM-Newton, one...
Quasi-periodic X-ray eruptions (QPEs) are a recently discovered phenomenon, the nature of which remains unclear. Based on their discovery in active galactic nuclei (AGN), explanations related to an AGN accretion disk, or potentially stellar tidal disruption event (TDE), were put forward. Following report QPEs apparently passive galaxies, alternatives including highly unequal mass compact object binaries have been proposed explain properties. We perform systematic study five known QPE host...
The ROSAT-selected tidal disruption event (TDE) candidate RX J133157.6-324319.7 (J1331), was detected in 1993 as a bright (0.2-2 keV flux of $(1.0 \pm 0.1) \times 10^{-12}$ erg s$^{-1}$ cm$^{-2}$), ultra-soft ($kT=0.11 0.03$ keV) X-ray flare from quiescent galaxy ($z=0.05189$). During its fifth All-Sky survey (eRASS5) 2022, SRG/eROSITA the repeated flaring J1331, where it had rebrightened to an observed 0.2-2 $(6.0 0.7) 10^{-13}$ cm$^{-2}$, with spectral properties ($kT=0.115 0.007$...
Context. Quasi-periodic eruptions (QPEs) are repeating thermal X-ray bursts associated with accreting massive black holes, the precise underlying physical mechanisms of which still unclear. Aims. We present a new candidate QPE source, AT 2019vcb (nicknamed Tormund by Zwicky Transient Facility Collaboration), was found during an archival search for QPEs in XMM-Newton archive. It first discovered 2019 as optical tidal disruption event (TDE) at z = 0.088, and its follow-up exhibited QPE-like...
X-ray quasi-periodic eruptions (QPEs) are intense repeating soft bursts from the nuclei of nearby galaxies. Their physical origin is still largely unconstrained, and several theoretical models have been proposed to date. We present here results a recent XMM-Newton observation GSN 069, galactic nucleus where QPEs were first discovered. After about two years absence, reappeared in we detect consecutive separated by much shorter recurrence time than ever before. Moreover, their intensities peak...
Abstract Quasi-periodic eruptions (QPEs) are luminous X-ray outbursts recurring on hour timescales, observed from the nuclei of a growing handful nearby low-mass galaxies. Their physical origin is still debated, and usually modeled as (a) accretion disk instabilities or (b) interaction supermassive black hole (SMBH) with lower mass companion in an extreme mass-ratio inspiral (EMRI). EMRI models can be tested several predictions related to short- long-term behavior QPEs. In this study, we...
Multi-wavelength extragalactic nuclear transients, particularly those detectable as multi-messengers, are among the primary drivers for next-generation observatories. X-ray quasi-periodic eruptions (QPEs) most recent and perhaps peculiar addition to this group. Here, we report a first estimate of volumetric rate QPEs based on four discoveries with eROSITA telescope onboard Spectrum Roentgen Gamma observatory. Under assumption, supported by suite simulated light curves, that these sources...
Quasi-periodic Eruptions (QPEs) represent a novel class of extragalactic X-ray transients that are known to repeat at roughly regular intervals few hours days. Their underlying physical mechanism is topic heated debate, with most models proposing they originate either from instabilities within the inner accretion flow or orbiting objects. At present, our knowledge how QPEs evolve over an extended timescale multiple years limited, except for unique QPE source GSN 069. In this study, we...
Binaries containing a compact object orbiting supermassive black hole are thought to be precursors of gravitational wave events, but their identification has been extremely challenging. Here, we report quasi-periodic variability in x-ray absorption, which interpret as outflows (QPOuts) from previously low-luminosity active galactic nucleus after an outburst, likely caused by stellar tidal disruption. We rule out several models based on observed properties and instead show using general...
X-ray quasi-periodic eruptions (QPEs) are a novel mode of variability in nearby galactic nuclei whose origin remains unknown. Their multi-wavelength properties poorly constrained, as studies have focused almost entirely on the band. Here we report time-resolved, coordinated Hubble Space Telescope far ultraviolet and XMM-Newton observations shortest period QPE source currently known, eRO-QPE2. We detect bright UV point ($L_{\rm FUV} \approx {\rm few} \times 10^{41}$ erg s$^{-1}$) that does...
Abstract X-ray quasiperiodic eruptions (QPEs) are a novel mode of variability in nearby galactic nuclei whose origin remains unknown. Their multiwavelength properties poorly constrained, as studies have focused almost entirely on the band. Here, we report time-resolved, coordinated Hubble Space Telescope far-ultraviolet (FUV) and XMM-Newton observations shortest period QPE source currently known, eRO-QPE2. We detect bright UV point ( L FUV ≈ few × 10 41 erg s −1 ) that does not show...
Quasi-periodic eruptions (QPEs) are recurrent X-ray bursts found so far in the nuclei of low-mass galaxies. Their trigger mechanism is still unknown, but recent models involving one or two stellar-mass companions around central massive ($\approx10^5-10^6$ solar masses) black hole have gathered significant attention. While these been compared only qualitatively with observations, phenomenology QPEs developing at a fast pace, potential to reveal new insights. Here we report observational...
Context . Massive black holes (MBHs) are typically hosted in the centres of massive galaxies but they appear to become rarer lower mass galaxies, where nuclear star clusters (NSCs) frequently instead. The transition region, both an MBH and NSC can co-exist, has been poorly studied date only a few dozen known host them. One avenue for detecting new with is look accretion signatures MBHs. Aims Here, we use SRG/eROSITA all-sky survey eRASS:4 data search X-ray accreting MBHs NSCs, while also...