The ASTRI Mini-Array is a next-generation system of nine imaging atmospheric Cherenkov telescopes that is going to be built at the Observatorio del Teide site. After a first phase, in which the ...instrument will be operated as an experiment prioritizing a schedule of primary science cases, an observatory phase is foreseen in which other significant targets will be pointed. We focus on the observational feasibility of extragalactic sources and on astrophysical processes that best complement and expand the ASTRI Mini-Array core science, presenting the most relevant examples that are at reach of detection over long-term time scales and whose observation can provide breakthrough achievements in the very-high energy extragalactic science. Such examples cover a wide range of γ-ray emitters, including the study of AGN low states in the multi-TeV energy range, the possible detection of Seyfert galaxies with long exposures and the searches of dark matter lines above 10 TeV. Simulations of the presented objects show that the instrument performance will be competitive at multi-TeV energies with respect to current arrays of Cherenkov telescopes.
Abstract
The blazar
TXS 0506+056
got into the spotlight of the astrophysical community in 2017 September, when a high-energy neutrino detected by IceCube (IceCube-170922A) was associated at the 3
σ
...level with a
γ
-ray flare from this source. This multi-messenger photon-neutrino association remains, as per today, the most significant association ever observed. TXS 0506+056 was a poorly studied object before the IceCube-170922A event. To better characterize its broadband emission, we organized a multiwavelength campaign lasting 16 months (2017 November to 2019 February), covering the radio band (Metsähovi, OVRO), the optical/UV (ASAS-SN, KVA, REM, Swift/UVOT), the X-rays (Swift/XRT, NuSTAR), the high-energy
γ
rays (Fermi/LAT), and the very high-energy (VHE)
γ
rays (MAGIC). In
γ
rays, the behavior of the source was significantly different from the behavior in 2017: MAGIC observations show the presence of flaring activity during 2018 December, while the source only shows an excess at the 4
σ
level during the rest of the campaign (74 hr of accumulated exposure); Fermi/LAT observations show several short (on a timescale of days to a week) flares, different from the long-term brightening of 2017. No significant flares are detected at lower energies. The radio light curve shows an increasing flux trend that is not seen in other wavelengths. We model the multiwavelength spectral energy distributions in a lepto-hadronic scenario, in which the hadronic emission emerges as Bethe-Heitler and pion-decay cascade in the X-rays and VHE
γ
rays. According to the model presented here, the 2018 December
γ
-ray flare was connected to a neutrino emission that was too brief and not bright enough to be detected by current neutrino instruments.
Context.
QSO B1420+326 is a blazar classified as a flat-spectrum radio quasar (FSRQ). At the beginning of the year 2020, it was found to be in an enhanced flux state and an extensive multiwavelength ...campaign allowed us to trace the evolution of the flare.
Aims.
We search for very high-energy (VHE) gamma-ray emission from QSO B1420+326 during this flaring state. We aim to characterize and model the broadband emission of the source over different phases of the flare.
Methods.
The source was observed with a number of instruments in radio, near-infrared, optical (including polarimetry and spectroscopy), ultraviolet, X-ray, and gamma-ray bands. We use dedicated optical spectroscopy results to estimate the accretion disk and the dust torus luminosity. We performed spectral energy distribution modeling in the framework of combined synchrotron-self-Compton and external Compton scenario in which the electron energy distribution is partially determined from acceleration and cooling processes.
Results.
During the enhanced state, the flux of both SED components of QSO B1420+326 drastically increased and the peaks were shifted to higher energies. Follow-up observations with the MAGIC telescopes led to the detection of VHE gamma-ray emission from this source, making it one of only a handful of FSRQs known in this energy range. Modeling allows us to constrain the evolution of the magnetic field and electron energy distribution in the emission region. The gamma-ray flare was accompanied by a rotation of the optical polarization vector during a low -polarization state. Also, a new superluminal radio knot contemporaneously appeared in the radio image of the jet. The optical spectroscopy shows a prominent FeII bump with flux evolving together with the continuum emission and a MgII line with varying equivalent width.
ABSTRACT We present the serendipitous discovery of a projected pair of quasi-stellar objects (QSOs) with an angular separation of Δθ = 4.50 arcsec. The redshifts of the two QSOs are widely different: ...one, our program target, is a QSO with a spectrum consistent with being a narrow line Seyfert 1 active galactic nucleus at z = 2.05. For this target we detect Ly , C iv, and C iii. The other QSO, which by chance was included on the spectroscopic slit, is a Type 1 QSO at a redshift of z = 1.68, for which we detect C iv, C iii, and Mg ii. We compare this system to previously detected projected QSO pairs and find that only about a dozen previously known pairs have smaller angular separation.
Background: The aim of this work was to investigate adolescents′ propensity to donate blood, the incidence in this population of risk behaviors that limit and restrict the potential for blood ...donation, thus reducing the number of possible subjects suitable for donation, and the link between propensity to donate and healthy lifestyles. Materials and Methods: Adolescents were asked to complete an anonymous self-report questionnaire during class time. The questionnaire included ad hoc items designed to investigate the intention to donate blood and behaviors traditionally considered to put adolescents′ health "at risk." Participants were 201 students from northern Italy (range 12-19, M = 17.98, SD = 1.82; 38.9% male, 61.1% female). Results: About half of respondents perceived that they were able to donate blood and could overcome any obstacle that might prevent them from doing so. Some of the examined risk behaviors were widespread in the population under consideration. The linear regressions run show that there is no link between the propensity to give blood and a tendency to engage in healthy lifestyles. Conclusion: The study shows that adolescents demonstrate an interest in blood donation; however, it shows a real lack of "action" to make it happen: there is, indeed, a serious lack of attention to matters related to healthy lifestyles. In fact, adolescents are not aware of how to act to access the world of donation, with the risk that they present themselves at blood donation centers and are then found to be unfit to donate. The research offers many suggestions and implications.
The present work proposes to explore a phenomenon well known in the world of blood donation, but little explored by literature: multi-affiliations. By that term, in this paper we mean blood donors’ ...engagement in multiple associations of various natures (donation, recreation, sports, etc.) simultaneously.
The first objective proposes to explore the phenomenon of multi-affiliations in descriptive terms; the second is to look into the differences—in terms of motivations, family-work-volunteerism reconciliation, life satisfaction, and membership satisfaction—between those who “only” carry out blood donation activity and those who instead participate in multiple associative realities concurrently.
Participating in the research were 2674 donors from the Italian Association of Blood Donors (AVIS) (age range 18–65; 66.6% male) to which a self-report questionnaire was administered in the waiting rooms of numerous blood donation centers.
Regarding the first objective, it emerged that only 35.9% of the participants “only” donate blood, while a good 64.1% is engaged also in other associations. Regarding the second objective, statistically significant differences emerge regarding many of the variables considered: social, values, ego-protection, and career motivation; capacity to reconcile family-volunteering and work-volunteering; life satisfaction; and membership satisfaction.
The study offers precious information to the agencies that handle recruiting and retaining of donors. The agencies in fact can take away information on how to improve the multi-affiliations of their donors, an aspect that can facilitate their long-term retention.
Patients with fatty liver (FL) disease have a high risk of developing diabetes and cardiovascular diseases. The aim was to evaluate the association between FL, insulin resistance (IR), coronary heart ...disease (CHD) risk, and early atherosclerosis in a large European population (RISC Study). In 1,307 nondiabetic subjects (age 30‐60 years) recruited at 19 centers, we evaluated liver enzymes, lipids, insulin sensitivity (by euglycemic‐hyperinsulinemic clamp), glucose tolerance (by 75 g oral glucose tolerance test), carotid atherosclerosis as intima media thickness (IMT), CHD risk by the Framingham Heart study prediction score, and physical activity (by accelerometer). The presence of FL was estimated using the fatty liver index (FLI; >60, likelihood >78% presence FL; FLI <20 likelihood >91% absence of FL). Subjects were divided into three groups: G1: FLI <20 (n = 608); G3: FLI >60 (n = 234), G2: intermediate group (n = 465). Compared to G1, G3 included more men (70% versus 24%) and people with impaired glucose tolerance (23% versus 5%). IMT increased with FLI (G3 = 0.64 ± 0.08 versus G1 = 0.58 ± 0.08 mm, P < 0.0001). FLI was associated with increased CHD risk (r = 0.48), low‐density lipoprotein cholesterol (r = 0.33), alanine aminotransferase (r = 0.48), aspartate aminotransferase (r = 0.25), systolic blood pressure (r = 0.39) and IMT (r = 0.30), and reduced insulin sensitivity (r = −0.43), high‐density lipoprotein cholesterol (r = −0.50), adiponectin (r = −0.42), and physical activity (r = −0.16, all P < 0.0001). The correlations hold also in multivariate analysis after adjusting for age, gender, and recruiting center. Conclusion: In middle‐age nondiabetic subjects, increased IMT, CHD risk, and reduced insulin sensitivity are associated with high values of FLI. (HEPATOLOGY 2009.)
Abstract Background The economic crisis has exasperated people's feelings of loneliness; job instability often does not allow people to commit to voluntary work. The present work proposes to examine ...whether the motivations to donate blood have changed before and during the period of economic crisis, taking into consideration donors' gender. We adopted Omoto & Snyder's functionalist approach, which states that blood donation serves different functions for any one person, who may have different motivations from those held by other people. Materials and Methods We compared six-year pre–post (t1 “pre-crisis”: 2008 – t2 “during the crisis”: 2014) data on a sample of blood donors in a single blood donation center situated in Northern Italy. T-test was used for data analysis. Three hundred thirty donors (age range 18–60, M = 32.6, SD = 9.53; 54.5% male) were administered a survey at t1 and 444 (age range 18–60, M = 37.8, SD = 10.16; 68% male) six years later at t2. In both surveys, participants were administered a questionnaire with socio-demographic items and a version of Omoto & Snyder's Motivations to Volunteer scale adapted to blood donation. Results Donors' motivation priorities did not vary over time. Values and Self-enhancement motivations are the most prevalent. Knowledge and Ego-protection motivations decreased with the upsurge of the crisis. Women, in general, report higher mean values than men do for Values and Ego-protection motivations. Conclusion These results can offer valuable clues for the agencies that manage blood collection.
Context. The study of high-redshift bright quasars is crucial to gather information about the history of galaxy assembly and evolution. Variability analyses can provide useful data on the physics of ...quasar processes and their relation with the host galaxy. Aims. In this study, we aim to measure the black hole mass of the bright lensed BAL QSO APM 08279+5255 at z = 3.911 through reverberation mapping, and to update and extend the monitoring of its C IV absorption line variability. Methods. We perform the first reverberation mapping of the Si IV and C IV emission lines for a high-luminosity quasar at high redshift with the use of 138 R-band photometric data and 30 spectra available over 16 years of observations. We also cross-correlate the C IV absorption equivalent width variations with the continuum light curve to estimate the recombination time lags of the various absorbers and infer the physical conditions of the ionised gas. Results. We find a reverberation-mapping time lag of ~900 rest-frame days for both Si IV and C IV emission lines. This is consistent with an extension of the BLR size-to-luminosity relation for active galactic nuclei up to a luminosity of ~1048 erg s-1, and implies a black hole mass of 1010 M⊙. Additionally, we measure a recombination time lag of ~160 days in the rest frame for the C IV narrow absorption system, which implies an electron density of the absorbing gas of ~2.5 × 104 cm-3. Conclusions. The measured black hole mass of APM 08279+5255 indicates that the quasar resides in an under-massive host-galaxy bulge with Mbulge ~ 7.5MBH, and that the lens magnification is lower than ~8. Finally, the inferred electron density of the narrow-line absorber implies a distance of the order of 10 kpc of the absorbing gas from the quasar, placing it within the host galaxy.
Context.
The BL Lac object 1ES 0647+250 is one of the few distant
γ
-ray emitting blazars detected at very high energies (VHEs; ≳100 GeV) during a non-flaring state. It was detected with the MAGIC ...telescopes during a period of low activity in the years 2009−2011 as well as during three flaring activities in the years 2014, 2019, and 2020, with the highest VHE flux in the last epoch. An extensive multi-instrument data set was collected as part of several coordinated observing campaigns over these years.
Aims.
We aim to characterise the long-term multi-band flux variability of 1ES 0647+250, as well as its broadband spectral energy distribution (SED) during four distinct activity states selected in four different epochs, in order to constrain the physical parameters of the blazar emission region under certain assumptions.
Methods.
We evaluated the variability and correlation of the emission in the different energy bands with the fractional variability and the Z-transformed discrete correlation function, as well as its spectral evolution in X-rays and
γ
rays. Owing to the controversy in the redshift measurements of 1ES 0647+250 reported in the literature, we also estimated its distance in an indirect manner through a comparison of the GeV and TeV spectra from simultaneous observations with
Fermi
-LAT and MAGIC during the strongest flaring activity detected to date. Moreover, we interpret the SEDs from the four distinct activity states within the framework of one-component and two-component leptonic models, proposing specific scenarios that are able to reproduce the available multi-instrument data.
Results.
We find significant long-term variability, especially in X-rays and VHE
γ
rays. Furthermore, significant (3−4
σ
) correlations were found between the radio, optical, and high-energy (HE)
γ
-ray fluxes, with the radio emission delayed by about ∼400 days with respect to the optical and
γ
-ray bands. The spectral analysis reveals a harder-when-brighter trend during the non-flaring state in the X-ray domain. However, no clear patterns were observed for either the enhanced states or the HE (30 MeV <
E
< 100 GeV) and VHE
γ
-ray emission of the source. The indirect estimation of the redshift yielded a value of
z
= 0.45 ± 0.05, which is compatible with some of the values reported in the literature. The SEDs related to the low-activity state and the three flaring states of 1ES 0647+250 can be described reasonably well with the both one-component and two-component leptonic scenarios. However, the long-term correlations indicate the need for an additional radio-producing region located about 3.6 pc downstream from the gamma-ray producing region.
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