Generation Of Telescopes Research Articles

Exoplanet Geology: What Can We Learn from Current and Future Observations?

OVERVIEW Nearly 30 years after the discovery of the first exoplanet around a main sequence star, thousands of planets have now been confirmed. These discoveries have completely revolutionized our understanding of planetary systems, revealing types of planets that do not exist in our solar system but are common in extrasolar systems, and a wide range of system architectures. Our solar system is clearly not the default for planetary systems. The community is now moving beyond basic characterization of exoplanets (mass, radius, and orbits) towards a deeper characterization of their atmospheres and even surfaces. With improved observational capabilities there is potential to now probe the geology of rocky exoplanets; this raises the possibility of an analogous revolution in our understanding of rocky planet evolution. However, characterizing the geology or geological processes occurring on rocky exoplanets is a major challenge, even with next generation telescopes. This chapter reviews what we may be able to accomplish with these efforts in the near-term and long-term. In the near-term, the James Webb Space Telescope (JWST) is revealing which rocky planets lose versus retain their atmospheres. This chapter discusses the implications of such discoveries, including how even planets with no or minimal atmospheres can still provide constraints on surface geology and long-term geological evolution. Longer-term possibilities are then reviewed, including whether the hypothesis of climate stabilization by the carbonate–silicate cycle can be tested by next generation telescopes. New modeling strategies sweeping through ranges of possibly evolutionary scenarios will be needed to use the current and future observations to constrain rocky exoplanet geology and evolution.

Low-frequency pulse-jitter measurement with the uGMRT I : PSR J0437–4715

Abstract High-precision pulsar timing observations are limited in their accuracy by the jitter noise that appears in the arrival time of pulses. Therefore, it is important to systematically characterise the amplitude of the jitter noise and its variation with frequency. In this paper, we provide jitter measurements from low-frequency wideband observations of PSR J0437–4715 using data obtained as part of the Indian Pulsar Timing Array experiment. We were able to detect jitter in both the 300 - 500 MHz and 1260 - 1460 MHz observations of the upgraded Giant Metrewave Radio Telescope (uGMRT). The former is the first jitter measurement for this pulsar below 700 MHz, and the latter is in good agreement with results from previous studies. In addition, at 300 - 500 MHz, we investigated the frequency dependence of the jitter by calculating the jitter for each sub-banded arrival time of pulses. We found that the jitter amplitude increases with frequency. This trend is opposite as compared to previous studies, indicating that there is a turnover at intermediate frequencies. It will be possible to investigate this in more detail with uGMRT observations at 550 - 750 MHz and future high sensitive wideband observations from next generation telescopes, such as the Square Kilometre Array. We also explored the effect of jitter on the high precision dispersion measure (DM) measurements derived from short duration observations. We find that even though the DM precision will be better at lower frequencies due to the smaller amplitude of jitter noise, it will limit the DM precision for high signal-to-noise observations, which are of short durations. This limitation can be overcome by integrating for a long enough duration optimised for a given pulsar.

Analysis of chiral oxirane molecules in preparation for next generation telescopes: A review, new analysis, & a chiral molecule database

Human biology has a preference for left-handed chiral molecules and an outstanding question is if this is imposed through astrophysical origins. We aim to evaluate the known information about chiral molecules within astrophysical and astrochemical databases, evaluate chemical modeling accuracy, and use high-level CCSD(T) calculations to characterize propylene oxide and other oxirane variants. By comparing these computational values with past laboratory experiments, we find a 99.9% similarity. We also have put together a new database dedicated to chiral molecules and variants of chiral molecules to assist in answering this question.

A star is born – using next generation telescopes to explore star formation

A star is born – using next generation telescopes to explore star formation

Polytropic fits of modern and unified equations of state

Equations of state for a cold neutron star's interior are presented in three-column tables that relate the baryonic density, the energy density, and the pressure. A few analytical expressions for those tables have been established these past two decades, as a convenient way to present a large number of nuclear models for neutron star matter. Some of those analytical representations are based on nonunified equations of state, in the sense that the high and the low density part of the star are not computed with the same nuclear model. Fits of equations of state based on a piecewise polytropic representation are revised by using unified tables of equations of state, that is to say models which have been calculated consistently for the core and the crust. A set of 52 unified equations of state is chosen. Each one is divided in seven polytropes via an adaptive segmentation, and two parameters per polytrope are fitted to the tabulated equation of state. The total mass, radius, tidal deformability and moment of inertia of neutron stars are modelled from the fits and compared with the quantities calculated from the original tables to ensure the accuracy of the fits on macroscopic parameters. We provide the polytropes parameters for 15 nucleonic relativistic mean field models, seven hyperonic relativistic mean field models, five hybrid relativistic mean-field models, 24 nucleonic Skyrme models, and one ab initio model. The fit error on the macroscopic parameters of neutron stars is small and well within the estimated measurement accuracy from current and next generation telescopes.

A RUL Estimation System from Clustered Run-to-Failure Degradation Signals.

The prognostics and health management disciplines provide an efficient solution to improve a system’s durability, taking advantage of its lifespan in functionality before a failure appears. Prognostics are performed to estimate the system or subsystem’s remaining useful life (RUL). This estimation can be used as a supply in decision-making within maintenance plans and procedures. This work focuses on prognostics by developing a recurrent neural network and a forecasting method called Prophet to measure the performance quality in RUL estimation. We apply this approach to degradation signals, which do not need to be monotonical. Finally, we test our system using data from new generation telescopes in real-world applications.

Third-Generation Calibrations for MeerKAT Observation

Superclusters and galaxy clusters offer a wide range of astrophysical science topics with regards to studying the evolution and distribution of galaxies, intra-cluster magnetization mediums, cosmic ray accelerations and large scale diffuse radio sources all in one observation. Recent developments in new radio telescopes and advanced calibration software have completely changed data quality that was never possible with old generation telescopes. Hence, radio observations of superclusters are a very promising avenue to gather rich information of a large-scale structure (LSS) and their formation mechanisms. These newer wide-band and wide field-of-view (FOV) observations require state-of-the-art data analysis procedures, including calibration and imaging, in order to provide deep and high dynamic range (DR) images with which to study the diffuse and faint radio emissions in supercluster environments. Sometimes, strong point sources hamper the radio observations and limit the achievement of a high DR. In this paper, we have shown the DR improvements around strong radio sources in the MeerKAT observation of the Saraswati supercluster by applying newer third-generation calibration (3GC) techniques using CubiCal and killMS software. We have also calculated the statistical parameters to quantify the improvements around strong radio sources. This analysis advocates for the use of new calibration techniques to maximize the scientific returns from new-generation telescopes.

Transient Radio Signatures from Neutron Star Encounters with QCD Axion Miniclusters.

The QCD axion is expected to form dense structures known as axion miniclusters if the Peccei-Quinn symmetry is broken after inflation. Miniclusters that have survived until today will interact with neutron stars (NSs) in the MilkyWay to produce transient radio signals from axion-photon conversion in the NS magnetosphere. We quantify the properties of these encounters and find that they occur frequently [O(1-100)day^{-1}], last between a day and a few months, are spatially clustered toward the Galactic Center, and can reach observable fluxes. These radio transients are within reach of current generation telescopes and therefore offer a promising pathway to discovering QCD axion dark matter.

Magnetohydrodynamic Waves in Open Coronal Structures

Modern observatories have revealed the ubiquitous presence of magnetohydrodynamic waves in the solar corona. The propagating waves (in contrast to the standing waves) are usually originated in the lower solar atmosphere which makes them particularly relevant to coronal heating. Furthermore, open coronal structures are believed to be the source regions of solar wind, therefore, the detection of MHD waves in these structures is also pertinent to the acceleration of solar wind. Besides, the advanced capabilities of the current generation telescopes have allowed us to extract important coronal properties through MHD seismology. The recent progress made in the detection, origin, and damping of both propagating slow mangetoacoustic waves and kink (Alfv\'{e}nic) waves is presented in this review article especially in the context of open coronal structures. Where appropriate, we give an overview on associated theoretical modelling studies. A few of the important seismological applications of these waves are discussed. The possible role of Aflv\'{e}nic waves in the acceleration of solar wind is also touched upon.

Estimating the neutrino flux from choked gamma-ray bursts

The strong constraints from the Fermi-LAT data on the isotropic gamma-ray background suggest that the neutrinos observed by IceCube might possibly come from sources that are hidden to gamma-ray observations. A possibility recently discussed in the literature is that neutrinos may come from jets of collapsing massive stars which fail to break out of the stellar envelope, and for this reason they are known as choked jets, or choked Gamma-Ray Bursts (GRBs). In this paper, we estimate the neutrino flux and spectrum expected from these sources, focusing on Type II SNe. We perform detailed calculations of pγ interactions, accounting for all the neutrino production channels and scattering angles. We provide predictions of expected event rates for operating neutrino telescopes, such as ANTARES and IceCube, as well as for the future generation telescope KM3NeT. We find that for GRB energies channeled into protons spanning between ∼ 1051–1053 erg, choked GRBs may substantially contribute to the observed astrophysical neutrino flux, if their local rate is ∼ 80–1 Gpc-3yr-1 respectively.

Modelled 3D distribution of OH/IR stars in the Galactic disc

ABSTRACT We have modelled the 3D distribution of OH/IR stars in the Galactic plane, traced by 1612 MHz OH maser sources with classic double horned spectral profiles. We statistically analysed over 700 maser sources detected by the HI/OH/Recombination line survey of the Milky Way (THOR) and the Australia Telescope Compact Array interferometric follow-up observations of the Southern Parkes Large-Area Survey in Hydroxyl (SPLASH). With a simple model constructed from a classical density distribution of stars and luminosity functions of OH maser sources in the Galaxy, we estimate the scale height, or the half thickness of the OH/IR star distribution along the Galactic disc to be 90–290 pc. The simple model also implies that there are ∼4000 OH/IR stars hosting 1612 MHz OH masers along the Galactic Plane. Therefore, next generation telescopes such as the Australian Square Kilometre Array Pathfinder (ASKAP) and SKA Phase 1 will detect about 80 per cent of such OH/IR stars in the Galaxy at a 10 mJy detection limit. Comparing the data of previously detected circumstellar 1612 MHz OH maser sources with those of THOR and SPLASH, the maser source lifetime is estimated to be ∼300 yr. This is likely a lower limit, since non-detections of masers in some cases could be affected by the flux variation of the maser source.

Towards an astronomical science platform: Experiences and lessons learned from Chinese Virtual Observatory

In the era of big data astronomy, next generation telescopes and large sky surveys produce data sets at the TB or even PB level. Due to their large data volumes, these astronomical data sets are extremely difficult to transfer and analyze using personal computers or small clusters. In order to offer better access to data, data centers now generally provide online science platforms that enable analysis close to the data. The Chinese Virtual Observatory (China-VO) is one of the member projects in the International Virtual Observatory Alliance and it is dedicated to providing a research and education environment where globally distributed astronomy archives are simple to find, access, and interoperate. In this study, we summarize highlights of the work conducted at the China-VO, as well the experiences and lessons learned during the full life-cycle management of astronomical data. Finally, We discuss the challenges and future trends for astronomical science platforms.

Slow Degradation Fault Detection in a Harsh Environment

The ever increasing challenges posed by the science projects in astronomy have skyrocketed the complexity of the new generation telescopes. Due to the climate and sky requirements, these high-precision instruments are generally located in remote areas, suffering from the harsh environments around it. These modern telescopes not only produce massive amounts of scientific data, but they also generate an enormous amount of operational information. The Atacama Large Millimeter/submillimeter Array (ALMA) is one of these unique instruments, generating more than 50 Gb of operational data every day while functioning in conditions of extreme dryness and altitude. To maintain the array working under extreme conditions, the engineering teams must check over 130,000 monitoring points, combing through the massive datasets produced every day. To make this possible, predictive tools are needed to identify, hopefully beforehand, the occurrence of failures in all the different subsystems. This work presents a novel fault detection scheme for one of these subsystems, the Intermediate Frequency Processors (IFP). This subsystem is critical to process the information gathered by each antenna and communicate it, reliably, to the correlator for processing. Our approach is based on echo state networks, a configuration of artificial neural networks, used to learn and predict the signal patterns. These patterns are later compared to the actual signal, to identify failure modes. Additional preprocessing techniques were also added since the signal-to-noise ratio of the data used was very low. The proposed scheme was tested in over seven years of data from 132 IFPs at ALMA, showing an accuracy of over 70%. Furthermore, the detection was done several months earlier, on average, when compared to what human operators did. These results help the maintenance procedures, increasing reliability while reducing humans’ exposure to the harsh environment where the antennas are. Although applied to a specific fault, this technique is broad enough to be applied to other types of faults and settings.

Discrimination of heavy elements originating from Pop III stars in z = 3 intergalactic medium

ABSTRACT We investigate the distribution of metals in the cosmological volume at $z$ ∼ 3, in particular, provided by massive Population III (Pop III) stars using a cosmological N-body simulation in which a model of Pop III star formation is implemented. Owing to the simulation, we can choose minihaloes where Pop III star formation occurs at $z$ > 10 and obtain the spatial distribution of the metals at lower redshifts. To evaluate the amount of heavy elements provided by Pop III stars, we consider metal yield of pair-instability or core-collapse supernovae (SNe) explosions of massive stars. By comparing our results to the Illustris-1 simulation, we find that heavy elements provided by Pop III stars often dominate those from galaxies in low-density regions. The median value of the volume averaged metallicity is $Z\sim 10^{-4.5 - -2} \, \mathrm{Z}_{\odot }$ at the regions. Spectroscopic observations with the next generation telescopes are expected to detect the metals imprinted on quasar spectra.

FocusGEO observations of space debris at Geosynchronous Earth Orbit

A new generation telescope for objects at Geosynchronous Earth Orbit (GEO) was developed by Shanghai Astronomical Observatory at the end of 2017, it’s called FocusGEO telescope. The goal is to observe nearly all the GEO objects over the observation station near real-time. FocusGEO telescope consists of three refracting telescopes of 18 cm aperture and 22 cm focal length, forming a super-large rectangular field of view(FOV) of 3 × 9.5°×9.5°. Each 15 min FocusGEO telescope scans a strip of sky 112.9°long × 28.3°high, almost fully covers the GEO belt over the station. In early 2018, FocusGEO observations were carried out at the Lijiang Observatory site of Yunnan Observatory, the results show that FocusGEO can observe about 380 GEO objects over the station per night. Its observation completeness is over 90% to GEO objects catalogued by USSTRATCOM. In the case of exposure for 5 s, FocusGEO can observe 15 magnitude GEO objects. The observation precision is about 3″ in azimuth and elevation.

The gravitational and lensing-ISW bispectrum of 21 cm radiation

Cosmic Microwave Background experiments from COBE to Planck, have launched cosmology into an era of precision science, where many cosmological parameters are now determined to the percent level. Next generation telescopes, focussing on the cosmological 21cm signal from neutral hydrogen, will probe enormous volumes in the low-redshift Universe, and have the potential to determine dark energy properties and test modifications of Einstein's gravity. We study the 21cm bispectrum due to gravitational collapse as well as the contribution by line of sight perturbations in the form of the lensing-ISW bispectrum at low-redshifts ($z \sim 0.35-3$), targeted by upcoming neutral hydrogen intensity mapping experiments. We compute the expected bispectrum amplitudes and use a Fisher forecast model to compare power spectrum and bispectrum observations of intensity mapping surveys by CHIME, MeerKAT and SKA-mid. We find that combined power spectrum and bispectrum observations have the potential to decrease errors on the cosmological parameters by an order of magnitude compared to Planck. Finally, we compute the contribution of the lensing-ISW bispectrum, and find that, unlike for the cosmic microwave background analyses, it can safely be ignored for 21cm bispectrum observations.

GeV–TeV γ-rays produced by electrons in the kpc-scale jet as a result of Comptonization of the inner jet emission

A few radio galaxies have been discovered to emit GeV-TeV gamma-ray emission in spite of relatively large viewing angles of their jets. We consider a scenario in which such large angle gamma-ray emission is preferentially produced by isotropically distributed relativistic electrons in the kpc scale jet. These electrons comptonize soft, non-thermal radiation from the inner jet which is beamed due to its relativistic motion. In terms of such a model, we interpret recently discovered TeV gamma-ray emission from the kpc scale jets in Cen~A. Interestingly, due to the geometry of the inverse Compton scattering process, intensity of the gamma-ray emission from the counter-jet is predicted to be on a higher level than the emission from the jet. This is true provided that both, a jet and a counter-jet, are twins, i.e. the physical processes in the jet and counter-jet result in the acceleration of particles in a similar way. However, in general, the jet and counter-jet can differ significantly. Therefore, their relative contribution to the gamma-ray emission from the jets in Cen~A can become more complicated. Investigation of the distribution of the TeV gamma-ray emission along jets of nearby radio galaxies with the next generation telescopes should provide constraints on the considered model and the content of the kpc-scale jets.

GAMMA-400 Project

Extraterrestrial gamma-ray astronomy is now a source of a new knowledge in the fields of astrophysics, cosmic-ray physics, and the nature of dark matter. The next absolutely necessary step in the development of extraterrestrial high-energy gamma-ray astronomy is the improvement of the physical and technical characteristics of gamma-ray telescopes, especially their angular and energy resolutions. Such a new generation telescope will be GAMMA-400, currently under development. Together with an X-ray telescope, it will perform precise and detailed observations in the energy range of ~20 MeV to ~10 000 GeV and 3–30 keV the Galactic plane, especially, toward the Galactic Center, Fermi Bubbles, Crab, Cygnus, etc. The GAMMA-400 will operate in the highly elliptic orbit continuously for a long time with the unprecedented angular (~0.01◦ at Eγ = 100 GeV) and energy (~1% at Eγ = 100 GeV) resolutions, exceeding the Fermi-LAT as well as ground-based gamma-ray telescopes by a factor of 5–10. GAMMA-400 will permit resolving gamma rays from annihilation or decay of dark matter particles, identifyingmany discrete sources (many of which are variable), clarifying the structure of extended sources, specifying the data on the diffuse emission, as well as measuring electron + positron fluxes and specifying electron + positron spectrum in the energy range from 1 GeV to 10 000 GeV.

Capabilities of next generation telescopes for cosmic magnetism

AbstractThe next generation of radio telescopes offer significant improvement in bandwidth and survey speed. We examine the ability to resolve Faraday thick objects in Faraday space as a function of survey parameters. The necessary combination of λmax and λmin to resolve objects with modest Faraday thick components requires one or two surveys with instantaneous bandwidth 300 MHz to 750 MHz offered by next generation telescopes. For spiral galaxies, bandwidths in excess of 1.5 GHz are required. Correction for Galactic Faraday rotation must account for common gradients of order 10 rad m−2 per degree. How effective a new rotation measure grid is in probing the foreground depends on off-axis polarization calibration.

Modelling of Lyman-alpha emitting galaxies and ionized bubbles at the epoch of reionization

Understanding Ly$\alpha$ emitting galaxies (LAEs) can be a key to reveal cosmic reionization and galaxy formation in the early Universe. Based on halo merger trees and Ly$\alpha$ radiation transfer calculations, we model redshift evolution of LAEs and their observational properties at $z \ge 6$. We consider ionized bubbles associated with individual LAEs and IGM transmission of Ly$\alpha$ photons. We find that Ly$\alpha$ luminosity tightly correlates with halo mass and stellar mass, while the relation with star formation rate has a large dispersion. Comparing our models with the observed luminosity function by Konno et al., we suggest that LAEs at $z \sim 7$ have galactic wind of $V_{\rm out} \gtrsim 100~\rm km\, s^{-1}$ and HI column density of $N_{\rm HI} \gtrsim 10^{20}~\rm cm^{-2}$. Number density of bright LAEs rapidly decreases as redshift increases, due to both lower star formation rate and smaller HII bubbles. Our model predicts future wide deep surveys with next generation telescopes, such as JWST, E-ELT and TMT, can detect LAEs at $z \sim 10$ with a number density of $n_{\rm LAE} \sim {\rm a~few~} \times10^{-6} ~\rm Mpc^{-3}$ for the flux sensitivity of $10^{-18} ~\rm erg\, cm^{-2}\, s^{-1}$. By combining these surveys with future 21-cm observations, it could be possible to detect both LAEs with $L_{Ly\alpha} \gtrsim 10^{42}~\rm erg~s^{-1}$ and their associated giant HII bubbles with the size $\gtrsim 250 ~\rm kpc$ at $z \sim 10$.