arXiv subjects

Massimo Della Valle

Publications and source records attributed to Massimo Della Valle.

At least 37 records · Page 2Linked to original sources

arXiv2023

Nova Neutrinos in the Multi-Messenger Era

The recently discovered high energy emission from the recurrent nova RS Ophiuchi by Fermi-LAT ($>$ 100 MeV), H.E.S.S. and MAGIC ($>$ 100 GeV), hints towards a possible hadronic origin of this radiation component. From the observed high energy photon flux we derive the expected number of neutrino events that could be detected by present and future neutrino telescopes in the different energy ranges. We find that both hadronic and leptonic processes remain valid interpretations for this $ \ gamma $ emission. Preliminary estimates indicate that with the "next-generation" instrument IceCube-Gen2, the expected number of neutrino detections from Galactic novae is of the order of $\sim $ once per decade. Given the current uncertainties in the frequency of the occurrence of nova outbursts, the detection rate may possibly increase to up to once every $\sim $ three years.

astro-ph.HE↗

arXiv2023

Photometric and Spectroscopic Observations of GRB 190106A: Emission from Reverse and Forward Shocks with Late-time Energy Injection

Early optical observations of gamma-ray bursts can significantly contribute to the study of the central engine and physical processes therein. However, of the thousands observed so far, still only a few have data at optical wavelengths in the first minutes after the onset of the prompt emission. Here we report on GRB\,190106A, whose afterglow was observed in optical bands just 36 s after the {\em Swift}/BAT trigger, i.e., during the prompt emission phase. The early optical afterglow exhibits a bimodal structure followed by a normal decay, with a faster decay after $\sim \rm T_{0}+$1 day. We present optical photometric and spectroscopic observations of GRB\,190106A. We derive the redshift via metal absorption lines from Xinglong 2.16-m/BFOSC spectroscopic observations. From the BFOSC spectrum, we measure $z= 1.861\pm0.002$. The double-peak optical light curve is a significant feature predicted by the reverse-forward external shock model. The shallow decay followed by a normal decay in both the X-ray and optical light curves is well explained with the standard forward-shock model with late-time energy injection. Therefore, GRB\,190106A offers a case study for GRBs emission from both reverse and forward shocks.

astro-ph.HE↗

arXiv2023

SN 2021zny: an early flux excess combined with late-time oxygen emission suggests a double white dwarf merger event

We present a photometric and spectroscopic analysis of the ultra-luminous and slowly evolving 03fg-like Type Ia SN 2021zny. Our observational campaign starts from $\sim5.3$ hours after explosion (making SN 2021zny one of the earliest observed members of its class), with dense multi-wavelength coverage from a variety of ground- and space-based telescopes, and is concluded with a nebular spectrum $\sim10$ months after peak brightness. SN 2021zny displayed several characteristics of its class, such as the peak brightness ($M_{B}=-19.95$ mag), the slow decline ($Δm_{15}(B) = 0.62$ mag), the blue early-time colours, the low ejecta velocities and the presence of significant unburned material above the photosphere. However, a flux excess for the first $\sim1.5$ days after explosion is observed in four photometric bands, making SN 2021zny the third 03fg-like event with this distinct behavior, while its $+313$ d spectrum shows prominent [O I] lines, a very unusual characteristic of thermonuclear SNe. The early flux excess can be explained as the outcome of the interaction of the ejecta with $\sim0.04\:\mathrm{M_{\odot}}$ of H/He-poor circumstellar material at a distance of $\sim10^{12}$ cm, while the low ionization state of the late-time spectrum reveals low abundances of stable iron-peak elements. All our observations are in accordance with a progenitor system of two carbon/oxygen white dwarfs that undergo a merger event, with the disrupted white dwarf ejecting carbon-rich circumstellar material prior to the primary white dwarf detonation.

astro-ph.HE↗

arXiv2022

Unveiling the Universe with Emerging Cosmological Probes

The detection of the accelerated expansion of the Universe has been one of the major breakthroughs in modern cosmology. Several cosmological probes (CMB, SNe Ia, BAO) have been studied in depth to better understand the nature of the mechanism driving this acceleration, and they are being currently pushed to their limits, obtaining remarkable constraints that allowed us to shape the standard cosmological model. In parallel to that, however, the percent precision achieved has recently revealed apparent tensions between measurements obtained from different methods. These are either indicating some unaccounted systematic effects, or are pointing toward new physics. Following the development of CMB, SNe, and BAO cosmology, it is critical to extend our selection of cosmological probes. Novel probes can be exploited to validate results, control or mitigate systematic effects, and, most importantly, to increase the accuracy and robustness of our results. This review is meant to provide a state-of-art benchmark of the latest advances in emerging beyond-standard cosmological probes. We present how several different methods can become a key resource for observational cosmology. In particular, we review cosmic chronometers, quasars, gamma-ray bursts, standard sirens, lensing time-delay with galaxies and clusters, cosmic voids, neutral hydrogen intensity mapping, surface brightness fluctuations, stellar ages of the oldest objects, secular redshift drift, and clustering of standard candles. The review describes the method, systematics, and results of each probe in a homogeneous way, giving the reader a clear picture of the available innovative methods that have been introduced in recent years and how to apply them. The review also discusses the potential synergies and complementarities between the various probes, exploring how they will contribute to the future of modern cosmology.

astro-ph.CO↗

arXiv2022

Central engine of GRB170817A: Neutron star versus Kerr black hole based on multimessenger calorimetry and event timing

The central engine of GRB170817A post-merger to GW170817 is probed by GW-calorimetry and event timing, applied to a post-merger descending chirp which can potentially break the degeneracy in spin-down of a neutron star or black hole remnant by the relatively large energy reservoir in the angular momentum, $E_J$, of the latter according to the Kerr metric. This analysis derives from model-agnostic spectrograms with equal sensitivity to ascending and descending chirps generated by time-symmetric butterfly matched filtering. The sensitivity was calibrated by response curves generated by software injection experiments. The statistical significance for candidate emission from the central engine of GRB170817A is expressed by probabilities of false alarm (PFA; type I errors) derived from an event-timing analysis. PDFs were derived for start-time $t_s$, identified via high-resolution image analyses of the available spectrograms. For merged (H1,L1)-spectrograms of the LIGO detectors, a PFA $p_1$ derives from causality in $t_s$ given GW170817-GRB17081A. A statistically independent confirmation is presented in individual H1 and L1 analyses, in a second PFA $p_2$ of consistency in their respective observations of $t_s$. A combined PFA derives from their product since mean and (respectively) difference in timing are statistically independent. Applied to GW170817-GRB170817A, PFAs of event timing in $t_s$ produce $p_1=8.3\times 10^{-4}$ and $p_2=4.9\times 10^{-5}$ of a post-merger output ${\cal E}_{GW}\simeq 3.5\%M_\odot c^2$ ($p_1p_2=4.1\times 10^{-8}$, equivalent $Z$-score 5.48). ${\cal E}_{GW}$ exceeds $E_J$ of the hyper-massive neutron star in the immediate aftermath of GW170817, yet it is consistent with $E_J$ rejuvenated in delayed gravitational collapse to a Kerr black hole. Similar emission may be expected from energetic core-collapse supernovae producing black holes. (Abbr.)

astro-ph.HE↗

arXiv2022

Laboratory test of the VIS detector system of SOXS for the ESO-NTT telescope

SOXS is the new spectrograph for the ESO NTT telescope able to cover the optical and NIR bands thanks to two different arms: the UV-VIS (350-850 nm), and the NIR (800-2000 nm). In this article, we describe the final design of the visible camera cryostats, the test facilities for the CCD characterization, and the first results with the scientific detector. The UV-VIS detector system is based on a e2v CCD 44-82, a custom detector head coupled with the ESO Continuous Flowing Cryostat (CFC) cooling system and the New General Detector Controller (NGC) developed by ESO. The laboratory facility is based on an optical bench equipped with a Xenon lamp, filter wheels to select the wavelength, an integrating sphere, and a calibrated diode to measure the flux. This paper outlines the visible camera cryostat, the test facilities for the CCD characterization and the first results with the scientific detector in the laboratory and after the integration to the instrument.

astro-ph.IM↗

arXiv2022

Dynamic scheduling for SOXS instrument: environment, algorithms and development

We present development progress of the scheduler for the Son Of X-Shooter (SOXS) instrument at the ESO-NTT 3.58 meter telescope. SOXS will be a single object spectroscopic facility, consisting of a two-arms high-efficiency spectrograph covering the spectral range 350-2000 nanometer with a mean resolving power R$\approx$4500. SOXS will be uniquely dedicated to the UV-visible and near infrared follow up of astrophysical transients, with a very wide pool of targets available from the streaming services of wide-field telescopes, current and future. This instrument will serve a variety of scientific scopes in the astrophysical community, with each scope eliciting its specific requirements for observation planning, that the observing scheduler has to meet. Due to directions from the European Southern Observatory (ESO), the instrument will be operated only by La Silla staff, with no astronomer present on the mountain. This implies a new challenge for the scheduling process, requiring a fully automated algorithm that should be able to present the operator not only with and ordered list of optimal targets, but also with optimal back-ups, should anything in the observing conditions change. This imposes a fast-response capability to the scheduler, without compromising the optimization process, that ensures good quality of the observations. In this paper we present the current state of the scheduler, that is now almost complete, and of its web interface.

astro-ph.IM↗

arXiv2022

The Quality Check system architecture for Son-Of-X-Shooter SOXS

We report the implemented architecture for monitoring the health and the quality of the Son Of X-Shooter (SOXS) spectrograph for the New Technology Telescope in La Silla at the European Southern Observatory. Briefly, we report on the innovative no-SQL database approach used for storing time-series data that best suits for automatically triggering alarm, and report high-quality graphs on the dashboard to be used by the operation support team. The system is designed to constantly and actively monitor the Key Performance Indicators (KPI) metrics, as much automatically as possible, reducing the overhead on the support and operation teams. Moreover, we will also detail about the interface designed to inject quality checks metrics from the automated SOXS Pipeline (Young et al. 2022).

astro-ph.IM↗

arXiv2022

Progress on the SOXS NIR Spectrograph AIT

The Son Of X-Shooter (SOXS) is a single object spectrograph, built by an international consortium for the 3.58-m ESO New Technology Telescope at the La Silla Observatory, ranging from 350 to 2000 nm. In this paper, we present the progress in the AIT phase of the Near InfraRed (NIR) arm. We describe the different AIT phases of the cryo, vacuum, opto-mechanics and detector subsystems, that finally converged at the INAF-OAB premises in Merate (Italy), where the NIR spectrograph is currently being assembled and tested, before the final assembly on SOXS.

astro-ph.IM↗

arXiv2022

SOXS AIT: a paradigm for system engineering of a medium class telescope instrument

SOXS (SOn of X-Shooter) is a high-efficiency spectrograph with a mean Resolution-Slit product of 3500 over the entire band capable of simultaneously observing the complete spectral range 350-2000 nm. It consists of three scientific arms (the UV-VIS Spectrograph, the NIR Spectrograph and the Acquisition Camera) connected by the Common Path system to the NTT, and the Calibration Unit. We present an overview of the flow from the scientific to the technical requirements, and the realization of the sub-systems. Further, we give an overview of the methodologies used for planning and managing the assembly of the sub-systems, their integration and tests before the acceptance of the instrument in Europe (PAE) along with the plan for the integration of SOXS to the NTT. SOXS could be used as an example for the system engineering of an instrument of moderate complexity, with a large geographic spread of the team.

astro-ph.IM↗

arXiv2022

The Son-Of-X-shooter (SOXS) Data-Reduction Pipeline

The Son-Of-XShooter (SOXS) is a single object spectrograph (UV-VIS & NIR) and acquisition camera scheduled to be mounted on the ESO 3.58-m New Technology Telescope at the La Silla Observatory. Although the underlying data reduction processes to convert raw detector data to fully-reduced science ready data are complex and multi-stepped, we have designed the SOXS Data Reduction pipeline with the core aims of providing end-users with a simple-to-use, well-documented command-line interface while also allowing the pipeline to be run in a fully automated state; streaming reduced data into the ESO Science Archive Facility without need for human intervention. To keep up with the stream of data coming from the instrument, there is the requirement to optimise the software to reduce each observation block of data well within the typical observation exposure time. The pipeline is written in Python 3 and has been built with an agile development philosophy that includes CI and adaptive planning.

astro-ph.IM↗

arXiv2022

Shocks in the outflow of the RS Oph 2021 eruption observed with X-ray gratings

The 2021 outburst of the symbiotic recurrent nova RS Oph was observed with the Chandra High Energy Transmission Gratings (HETG) on day 18 after optical maximum and with XMM-Newton and its Reflection Grating Spectrographs (RGS) on day 21, before the supersoft X-ray source emerged and when the emission was due to shocked ejecta. The absorbed flux in the HETG 1.3-31 Angstrom range was 2.6 x 10(-10) erg/cm(-2)/s, three orders of magnitude lower than the gamma-ray flux measured on the same date. The spectra are well fitted with two components of thermal plasma in collisional ionization equilibrium, one at a temperature ~0.75 keV, and the other at temperature in the 2.5-3.4 keV range. With the RGS we measured an average flux 1.53 x 10(-10) erg/cm(-2)/s in the 5-35 Angstrom range, but the flux in the continuum and especially in the lines in the 23-35 Angstrom range decreased during the 50 ks RGS exposure by almost 10%, indicating short term variability on hours' time scale. The RGS spectrum can be fitted with three thermal components, respectively at plasma temperature between 70 and 150 eV, 0.64 keV and 2.4 keV. The post-maximum epochs of the exposures fall between those of two grating spectra observed in the 2006 eruption on days 14 and 26: they are consistent with a similar spectral evolution, but in 2021 cooling seems to have been more rapid. Iron is depleted in the ejecta with respect to solar values, while nitrogen is enhanced.

astro-ph.HE↗

arXiv2022

Weak Mass Loss from the Red Supergiant Progenitor of the Type II SN 2021yja

We present high-cadence optical, ultraviolet (UV), and near-infrared data of the nearby ($D\approx23$ Mpc) Type II supernova (SN) 2021yja. Many Type II SNe show signs of interaction with circumstellar material (CSM) during the first few days after explosion, implying that their red supergiant (RSG) progenitors experience episodic or eruptive mass loss. However, because it is difficult to discover SNe early, the diversity of CSM configurations in RSGs has not been fully mapped. SN 2021yja, first detected within ${\approx}5.4$ hours of explosion, shows some signatures of CSM interaction (high UV luminosity, radio and x-ray emission) but without the narrow emission lines or early light curve peak that can accompany CSM. Here we analyze the densely sampled early light curve and spectral series of this nearby SN to infer the properties of its progenitor and CSM. We find that the most likely progenitor was an RSG with an extended envelope, encompassed by low-density CSM. We also present archival Hubble Space Telescope imaging of the host galaxy of SN 2021yja, which allows us to place a stringent upper limit of ${\lesssim}9\ M_\odot$ on the progenitor mass. However, this is in tension with some aspects of the SN evolution, which point to a more massive progenitor. Our analysis highlights the need to consider progenitor structure when making inferences about CSM properties, and that a comprehensive view of CSM tracers should be made to give a fuller view of the last years of RSG evolution.

astro-ph.HE↗

arXiv2021

Detection of $^7$Be II in the Small Magellanic Cloud

We analyse high resolution spectra of two classical novae that exploded in the Small Magellanic Cloud. $^7$Be II resonance transitions are detected in both ASASSN-19qv and ASASSN-20ni novae. This is the first detection outside the Galaxy and confirms that thermo-nuclear runaway reactions, leading to the $^7$Be formation, are effective also in the low metallicity regime, characteristic of the SMC. Derived yields are of N($^7$Be=$^7$Li)/N(H) = (5.3 $\pm$ 0.2) $\times$ 10$^{-6}$ which are a factor 4 lower than the typical values of the Galaxy. Inspection of two historical novae in the Large Magellanic Cloud observed with IUE in 1991 and 1992 showed also the possible presence of $^7$Be and similar yields. For an ejecta of $M_{H,ej} =$ 10$^{-5}$ M$_{\odot}$, the amount of $^7$Li produced is of $M_{^7 Li} = (3.7 \pm 0.6) \times 10^{-10}$ M$_{\odot}$ per nova event. Detailed chemical evolutionary model for the SMC shows that novae could have made an amount of lithium in the SMC corresponding to a fractional abundance of A(Li) $\approx$ 2.6. Therefore, it is argued that a comparison with the abundance of Li in the SMC, as measured by its interstellar medium, could effectively constrain the amount of the initial abundance of primordial Li, which is currently controversial.

astro-ph.SR↗

arXiv2021

Less than 1% of Core-Collapse Supernovae in the local universe occur in elliptical galaxies

We present observations of three Core-collapse supernovae (CCSNe) in elliptical hosts, detected by the Zwicky Transient Facility Bright Transient Survey (BTS). SN 2019ape is a SN Ic that exploded in the main body of a typical elliptical galaxy. Its properties are consistent with an explosion of a regular SN Ic progenitor. A secondary g-band light curve peak could indicate interaction of the ejecta with circumstellar material (CSM). An H$α$-emitting source at the explosion site suggests a residual local star formation origin. SN 2018fsh and SN 2020uik are SNe II which exploded in the outskirts of elliptical galaxies. SN 2020uik shows typical spectra for SNe II, while SN 2018fsh shows a boxy nebular H$α$ profile, a signature of CSM interaction. We combine these 3 SNe with 7 events from the literature and analyze their hosts as a sample. We present multi-wavelength photometry of the hosts, and compare this to archival photometry of all BTS hosts. Using the spectroscopically complete BTS we conclude that $0.3\%^{+0.3}_{-0.1}$ of all CCSNe occur in elliptical galaxies. We derive star-formation rates and stellar masses for the host-galaxies and compare them to the properties of other SN hosts. We show that CCSNe in ellipticals have larger physical separations from their hosts compared to SNe Ia in elliptical galaxies, and discuss implications for star-forming activity in elliptical galaxies.

astro-ph.HE↗

arXiv2020

The SOXS scheduler for remote operation at LaSilla:Concept and design

In this paper we present the SOXS Scheduler, a web-based application aimed at optimising remote observations at the NTT-ESO in the context of scientific topics of both the SOXS Consortium and regular ESO proposals.This paper will give details of how detected transients from various surveys are inserted, prioritised, and selected for observations with SOXS at the NTT while keeping the correct sharing between GTO time (for the SOXSConsortium) and the regularly approved observing time from ESO proposals. For the 5-years of operation ofSOXS this vital piece of software will provide a night-by-night dynamical schedule, allowing the user to face rapid changes during the operations that might come from varying weather conditions or frequent target of opportunity (ToO) observations that require a rapid response. The scheduler is developed with high available and scalable architecture in mind and it implements the state-of-the-art technologies for API Restful application like Docker Containers, API Gateway, and Python-based Flask frameworks.

astro-ph.IM↗

arXiv2020

The SOXS Data-Reduction Pipeline

The SOXS is a dual-arm spectrograph (UV-VIS & NIR) and AC due to mounted on the ESO 3.6m NTT in La Silla. Designed to simultaneously cover the optical and NIR wavelength range from 350-2050 nm, the instrument will be dedicated to the study of transient and variable events with many Target of Opportunity requests expected. The goal of the SOXS Data Reduction pipeline is to use calibration data to remove all instrument signatures from the SOXS scientific data frames for each of the supported instrument modes, convert this data into physical units and deliver them with their associated error bars to the ESO SAF as Phase 3 compliant science data products, all within 30 minutes. The primary reduced product will be a detrended, wavelength and flux calibrated, telluric corrected 1D spectrum with UV-VIS + NIR arms stitched together. The pipeline will also generate QC metrics to monitor telescope, instrument and detector health. The pipeline is written in Python 3 and has been built with an agile development philosophy that includes adaptive planning and evolutionary development. The pipeline is to be used by the SOXS consortium and the general user community that may want to perform tailored processing of SOXS data. Test driven development has been used throughout the build using `extreme' mock data. We aim for the pipeline to be easy to install and extensively and clearly documented.

astro-ph.IM↗

arXiv2020

The AIV strategy of the Common Path of Son of X-Shooter

Son Of X-Shooter (SOXS) is a double-armed (UV-VIS, NIR) spectrograph designed to be mounted at the ESO-NTT in La Silla, now in its Assembly Integration and Verification (AIV) phase. The instrument is designed following a modular approach so that each sub-system can be integrated in parallel before their assembly at system level. INAF-Osservatorio Astronomico di Padova will deliver the Common Path (CP) sub-system, which represents the backbone of the entire instrument. In this paper, we describe the foreseen operation for the CP alignment and we report some results already achieved, showing that we envisaged the suitable setup and the strategy to meet the opto-mechanical requirements.

astro-ph.IM↗