NICER Study of Pulsed Thermal X-Rays from Calvera: A Neutron Star Born in the Galactic Halo?

Calvera (1RXS J141256.0+792204) is an isolated neutron star detected only through its thermal X-ray emission. Its location at high Galactic latitude (b = +37 ) is unusual if Calvera is a relatively young pulsar, as suggested by its spin period (59 ms) and period derivative (3.2 10-15 s s-1). Using the Neutron Star Interior Composition Explorer, we obtained a phase-connected timing solution spanning four years, which allowed us to measure the second derivative of the frequency d? ? =-2.5× 10-23 Hz s-2 and to reveal timing noise consistent with that of normal radio pulsars. A magnetized hydrogen atmosphere model, covering the entire star surface, provides a good description of the phase-resolved spectra and energy-dependent pulsed fraction. However, we found that a temperature map more anisotropic than that produced by a dipole field is required, with a hotter zone concentrated toward the poles. By adding two small polar caps, we found that the surface effective temperature and that of the caps are ~0.1 and ~0.36 keV, respectively. The inferred distance is ~3.3 kpc. We confirmed the presence of an absorption line at 0.7 keV associated with the emission from the whole star surface, difficult to interpret as a cyclotron feature and more likely originating from atomic transitions. We searched for pulsed ?-ray emission by folding seven years of Fermi-LAT data using the X-ray ephemeris, but no evidence for pulsations was found. Our results favor the hypothesis that Calvera is a normal rotation-powered pulsar, with the only peculiarity of being born at a large height above the Galactic disk

Galactic observatory science with the ASTRI Mini-Array at the Observatorio del Teide

The ASTRI (Astrofisica con Specchi a Tecnologia Replicante Italiana) Mini-Array will be composed of nine imaging atmospheric Cherenkov telescopes at the Observatorio del Teide site. The array will be best suited for astrophysical observations in the 0.3-200 TeV range with an angular resolution of few arc-minutes and an energy resolution of 10-15%. A core-science programme in the first four years will be devoted to a limited number of key targets, addressing the most important open scientific questions in the very-high energy domain. At the same time, thanks to a wide field of view of about 10 degrees, ASTRI Mini-Array will observe many additional field sources, which will constitute the basis for the long-term observatory programme that will eventually cover all the accessible sky. In this paper, we review different astrophysical Galactic environments, e.g. pulsar wind nebulae, supernova remnants, and gamma -ray binaries, and show the results from a set of ASTRI Mini-Array simulations of some of these field sources made to highlight the expected performance of the array (even at large offset angles) and the important additional observatory science that will complement the core-science program

Sensitivity of the Cherenkov Telescope Array to TeV photon emission from the Large Magellanic Cloud

A deep survey of the Large Magellanic Cloud at ∼0.1-100 TeV photon energies with the Cherenkov Telescope Array is planned. We assess the detection prospects based on a model for the emission of the galaxy, comprising the four known TeV emitters, mock populations of sources, and interstellar emission on galactic scales. We also assess the detectability of 30 Doradus and SN 1987A, and the constraints that can be derived on the nature of dark matter. The survey will allow for fine spectral studies of N 157B, N 132D, LMC P3, and 30 Doradus C, and half a dozen other sources should be revealed, mainly pulsar-powered objects. The remnant from SN 1987A could be detected if it produces cosmic-ray nuclei with a flat power-law spectrum at high energies, or with a steeper index 2.3-2.4 pending a flux increase by a factor of >3-4 over ∼2015-2035. Large-scale interstellar emission remains mostly out of reach of the survey if its >10 GeV spectrum has a soft photon index ∼2.7, but degree-scale 0.1-10 TeV pion-decay emission could be detected if the cosmic-ray spectrum hardens above >100 GeV. The 30 Doradus star-forming region is detectable if acceleration efficiency is on the order of 1−10 per cent of the mechanical luminosity and diffusion is suppressed by two orders of magnitude within <100 pc. Finally, the survey could probe the canonical velocity-averaged cross-section for self-annihilation of weakly interacting massive particles for cuspy Navarro-Frenk-White profiles

Southern African Large Telescope Spectroscopy of BL Lacs for the CTA project

In the last two decades, very-high-energy gamma-ray astronomy has reached maturity: over 200 sources have been detected, both Galactic and extragalactic, by ground-based experiments. At present, Active Galactic Nuclei (AGN) make up about 40% of the more than 200 sources detected at very high energies with ground-based telescopes, the majority of which are blazars, i.e. their jets are closely aligned with the line of sight to Earth and three quarters of which are classified as high-frequency peaked BL Lac objects. One challenge to studies of the cosmological evolution of BL Lacs is the difficulty of obtaining redshifts from their nearly featureless, continuum-dominated spectra. It is expected that a significant fraction of the AGN to be detected with the future Cherenkov Telescope Array (CTA) observatory will have no spectroscopic redshifts, compromising the reliability of BL Lac population studies, particularly of their cosmic evolution. We started an effort in 2019 to measure the redshifts of a large fraction of the AGN that are likely to be detected with CTA, using the Southern African Large Telescope (SALT). In this contribution, we present two results from an on-going SALT program focused on the determination of BL Lac object redshifts that will be relevant for the CTA observatory

The Software Architecture and development approach for the ASTRI Mini-Array gamma-ray air-Cherenkov experiment at the Observatorio del Teide

The ASTRI Mini-Array is an international collaboration led by the Italian National Institute for Astrophysics (INAF) and devoted to the imaging of atmospheric Cherenkov light for very-high gamma-ray astronomy. The project is deploying an array of 9 telescopes sensitive above 1 TeV. In this contribution, we present the architecture of the software that covers the entire life cycle of the observatory, from scheduling to remote operations and data dissemination. The high-speed networking connection available between the observatory site, at the Canary Islands, and the Data Center in Rome allows for ready data availability for stereo triggering and data processing

Porcine embryonic stem cells : facts, challenges and hopes

Embryonic stem cells (ESCs) represent a promising tool for cell therapy, regenerative medicine and tissue repair. At the same time they constitute an invaluable model for basic investigations in developmental biology, nuclear reprogramming and differentiation process. ESCs are very unique due to their unlimited self-renewal ability and high plasticity that allow them to differentiate into all embryonic tissues. However, these properties have been so far only demonstrated in the mouse and, to a lesser extent, in man. Assessment of ESC capabilities in species different from the mouse is an ongoing topic of interest and is crucial in view of their potential use as experimental models in pre-clinical applications. The mouse model is not adequate when long-term effects of cell replacement need to be evaluated. The pig has been considered for a long time among the best models for pre-clinical development of therapeutic approaches and represents an innovative model due to its morphological and functional affinity with man; therefore, pig ESCs are attracting renewed interest. However, a number of open questions need to be addressed since no validated protocols for the derivation and maintenance of pig ESCs have yet been established. In the present paper data from the literature will be presented together with experimental evidence recently obtained in our laboratory. We will discuss aspects related to the timing of isolation, the initiation of primary cultures, the use of different culture conditions and cytokines. The identification of pluripotency-related molecular markers in the pig will also be examined. Finally, the ability to respond to specifically formulated medium with spontaneous as well as induced differentiation will be assessed

Derivation and characterization of pluripotent cell lines from pig embryos of different origins

Embryonic stem cells (ESCs) hold great promise for therapeutic use and represent a unique tool for investigating the process of self-renewal and differentiation. The properties that make ESCs unique are their capacity of unlimited self-renewal coupled with the property of re-entering the developmental process if returned inside a blastocyst. Such plasticity enable ESCs to form all embryonic tissues including germ cells. However, these remarkable properties, at present, have been demonstrated only for mouse ESCs even if cells with somehow more limited capacities have been derived in many different species including humans. The isolation of pluripotent embryonic cells lines from human embryos marked a crucial change of perspective in evaluating the properties defining an embryonic stem cell lines moving the focus from the generation of a germ-line chimera, obviously not feasible nor desirable in human, to the capacity of these cells to differentiate both in vivo and in vitro in fully mature and functional cell types of all kinds. Therefore, ESCs properties in species different from the mouse are being reassessed and re-evaluated, in view of their potential use as experimental models for the development of clinical applications. Among the species that may play a useful role in this field, the pig has a long-standing history as a prime animal model for pre-clinical biomedical applications and therefore, pig ESCs are attracting renewed interest. In this review, we will summarize the current knowledge on this topic and will contrast the relatively limited data available in this species with the much larger wealth of information available for mouse and human ESCs, in an attempt to assess whether or not pig ESCs can actually become a useful tool in the fast growing field of cell therapy

NICER Study of Pulsed Thermal X-Rays from Calvera: A Neutron Star Born in the Galactic Halo?

Calvera (1RXS J141256.0+792204) is an isolated neutron star detected only through its thermal X-ray emission. Its location at high Galactic latitude (b = +37 degrees) is unusual if Calvera is a relatively young pulsar, as suggested by its spin period (59 ms) and period derivative (3.2 x 10(-15) s s(-1)). Using the Neutron Star Interior Composition Explorer, we obtained a phase-connected timing solution spanning four years, which allowed us to measure the second derivative of the frequency (nu)over dot = -2.5 x 10(-23) Hz s(-2) and to reveal timing noise consistent with that of normal radio pulsars. A magnetized hydrogen atmosphere model, covering the entire star surface, provides a good description of the phase-resolved spectra and energy-dependent pulsed fraction. However, we found that a temperature map more anisotropic than that produced by a dipole field is required, with a hotter zone concentrated toward the poles. By adding two small polar caps, we found that the surface effective temperature and that of the caps are similar to 0.1 and similar to 0.36 keV, respectively. The inferred distance is similar to 3.3 kpc. We confirmed the presence of an absorption line at 0.7 keV associated with the emission from the whole star surface, difficult to interpret as a cyclotron feature and more likely originating from atomic transitions. We searched for pulsed gamma-ray emission by folding seven years of Fermi-LAT data using the X-ray ephemeris, but no evidence for pulsations was found. Our results favor the hypothesis that Calvera is a normal rotation-powered pulsar, with the only peculiarity of being born at a large height above the Galactic disk