Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
4.3
2.5
Journals
Universe
Special Issues
Universe: Feature Papers 2025—Space Science
share announcement

Universe: Feature Papers 2025—Space Science

A special issue of Universe (ISSN 2218-1997). This special issue belongs to the section "Space Science".

Deadline for manuscript submissions: 31 December 2025 | Viewed by 3168

Special Issue Editor

Dr. Ezio Caroli

E-Mail Website
Guest Editor
National Institute for Astrophysics (INAF), Astrophysics and Space Science Observatory of Bologna (OAS), Via P. Gobetti 101, 40129 Bologna, Italy
Interests: hard X and soft gamma ray polarimtery; broad band laue lens for hard X and soft gamma rays; room temperature solid state detector; code mask imaging; 2D/3D spectroscopic imager for X and gamma rays
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

This Special Issue aims to set itself at the cutting edge of the most recent advances and perspective in Space Science across the entire electromagnetic spectrum and in the intertwined links with other fields at all relevant scales from mutually fertilizing theoretical, phenomenological and experimental perspectives. Topics include, but are not limited to, the following:

  • space instrumentation from radio to gamma rays;
  • astrophysics from radio to gamma rays;
  • Multimessenger Astrophysics Space Intrumentation and Methods;
  • Astroparticle and Cosmic Rays from Space;
  • Space Astronomy Observational Techniques and Data Analysis Methods;
  • Extrasolar System Exploration;
  • Planetary Exploration and Sciences;
  • Interactions between Space Science and other Scientific Disciplines.

You are welcome to send short proposals for submissions of Feature Papers to our Editorial Office (universe@mdpi.com). They will be evaluated by Editors first, and the selected papers will be thoroughly and rigorously peer reviewed.

Dr. Ezio Caroli
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Universe is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • space mission/instrument/telescope concepts
  • inflight/in preparation space instrument
  • instrument performance evaluation
  • detectors technologies and perspectives
  • imaging and timing techniques and methods
  • spectroscopy and polarimetry techniques and methods
  • observational and analysis techniques and methods
  • cosmic ray sources emission models
  • methods for observing gravitational waves and counterparts at other frequencies (from radio to gamma)
  • methods and techniques for planetary (solar and extrasolar) science and exploration
  • space technology and biomedicine, environmental science, telecommunications, materials science

Benefits of Publishing in a Special Issue

  • Ease of navigation: Grouping papers by topic helps scholars navigate broad scope journals more efficiently.
  • Greater discoverability: Special Issues support the reach and impact of scientific research. Articles in Special Issues are more discoverable and cited more frequently.
  • Expansion of research network: Special Issues facilitate connections among authors, fostering scientific collaborations.
  • External promotion: Articles in Special Issues are often promoted through the journal's social media, increasing their visibility.
  • Reprint: MDPI Books provides the opportunity to republish successful Special Issues in book format, both online and in print.

Further information on MDPI's Special Issue policies can be found here.

Published Papers (6 papers)

Download All Papers
Order results
Result details
Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:

Research

19 pages, 1784 KiB  
Article
On the Relationship Between ULF Wave Power and Changes of Relativistic Electron Fluxes in the Outer Radiation Belt
by Christopher Lara, Victor A. Pinto, Javier Silva, Bea Zenteno-Quinteros and Pablo S. Moya
Universe 2025, 11(5), 151; https://doi.org/10.3390/universe11050151 - 6 May 2025
Viewed by 224
Abstract
We performed a statistical study on the correlation between electromagnetic Ultra Low Frequency (ULF) waves and the evolution of relativistic electron fluxes in the outer radiation belt for 3.1<L∗<6.0 during 101 geomagnetic storms that occurred between January 2013 [...] Read more.
We performed a statistical study on the correlation between electromagnetic Ultra Low Frequency (ULF) waves and the evolution of relativistic electron fluxes in the outer radiation belt for 3.1<L∗<6.0 during 101 geomagnetic storms that occurred between January 2013 and November 2018. We used the Van Allen Probes MagEIS and REPT instruments to study electron fluxes from 0.47 MeV to 5.2 MeV, and we utilized magnetic field data from EMFISIS to calculate magnetic field fluctuations parallel and perpendicular to the background magnetic field direction and obtain the ULF integrated power between 1 mHz and 10 mHz. We analyzed the data during the following three different time intervals: the main phase, the recovery phase, and the entire storm. We computed the Pearson’s correlation coefficient and mutual information score between the ratio of fluxes before and after each given phase and the total integrated ULF power during the same time interval. Our results show a significant correlation between ULF wave power and changes in fluxes of hundreds of keV electrons during the main phase of the storms and for MeV electrons during the recovery phase of the storms. By studying fluxes at independent L∗, the largest correlations correspond to changes in fluxes before and after the entire storm and ULF fluctuations parallel to the field, especially for L∗<4.6. We evaluated the drift resonance frequency for azimuthal wavenumber 1≤m≤10 and found that for all considered energies and frequencies, the drift resonance with Pc5 ULF waves may occur in our region of study, which is consistent with the statistical results. Full article
(This article belongs to the Special Issue Universe: Feature Papers 2025—Space Science)
►▼ Show Figures

Figure 1

22 pages, 4452 KiB  
Article
Influence of Solar Wind Driving and Geomagnetic Activity on the Variability of Sub-Relativistic Electrons in the Inner Magnetosphere
by Evangelia Christodoulou, Christos Katsavrias, Panayotis Kordakis and Ioannis A. Daglis
Universe 2025, 11(3), 101; https://doi.org/10.3390/universe11030101 - 18 Mar 2025
Viewed by 351
Abstract
Motivated by the need for more accurate radiation environment modeling, this study focuses on identifying and analyzing the drivers behind the sub-relativistic electron flux variations in the inner magnetosphere. We utilize electron flux data between 1 and 500 keV from the Hope and [...] Read more.
Motivated by the need for more accurate radiation environment modeling, this study focuses on identifying and analyzing the drivers behind the sub-relativistic electron flux variations in the inner magnetosphere. We utilize electron flux data between 1 and 500 keV from the Hope and MagEIS instruments on board the RBSP satellites, as well as from the FEEPS instruments on board the MMS spacecrafts, along with solar wind parameters and geomagnetic indices obtained from the OmniWeb2 and SuperMag data services. We calculate the correlation coefficients between these parameters and electron flux. Our analysis shows that substorm activity is a crucial driver of the source electron population (10–100 keV), while also showing that seed electrons (100–400 keV) are not purely driven by substorm events but also from enhanced convection/inward diffusion. By introducing time lags, we observed a delayed response of electron flux to changes in geospace conditions, and we identified specific time lag periods where the correlation is maximum. This work contributes to our broader understanding of the outer belt sub-relativistic electron dynamics and forms the basis for future research. Full article
(This article belongs to the Special Issue Universe: Feature Papers 2025—Space Science)
►▼ Show Figures

Figure 1

14 pages, 1434 KiB  
Article
From Known to Unknown: Cosmic Ray Transitions from the Sun, the Galaxy, and Extra-Galactic Systems
by Yuhua Yao, Yiqing Guo and Wei Liu
Universe 2025, 11(3), 96; https://doi.org/10.3390/universe11030096 - 14 Mar 2025
Viewed by 389
Abstract
The question of at which energy the transition from galactic to extra-galactic cosmic rays takes place has been a long-standing conundrum in cosmic ray physics. The sun stands out as the closest and clearest astrophysical accelerator of cosmic rays, while other objects within [...] Read more.
The question of at which energy the transition from galactic to extra-galactic cosmic rays takes place has been a long-standing conundrum in cosmic ray physics. The sun stands out as the closest and clearest astrophysical accelerator of cosmic rays, while other objects within and beyond the galaxy remain enigmatic. It is probable that the cosmic ray spectrum and mass components from these celestial sources share similarities, offering a novel approach to study their origin. In this study, we perform joint analysis of spectra and mass in the energy range from MeV to 10 EeV, and find the following: (1) lnA demonstrates three clear peaks, tagging component transition; (2) a critical variable Δ is adopted to define the location of the transition; (3) for protons, the knee is located at ∼1.8 PeV, and the boundary between the galaxy and extra-galaxy occurs at ∼60 PeV, marked by a spectral dip; and (4) the all-particle spectrum exhibits hardening at ∼60 PeV due to the contribution of nearby galaxies, and the extra-galaxy dominates ∼0.8 EeV. We hope the LHAASO experiment can perform spectral measurements of individual species to validate these specific observations. Full article
(This article belongs to the Special Issue Universe: Feature Papers 2025—Space Science)
►▼ Show Figures

Figure 1

12 pages, 635 KiB  
Article
Simultaneous Optical-to-X-Ray Spectrum of OJ 287 During Lowest X-Ray State: Synchrotron-Soft Tail and Harder X-Ray Spectrum
by Pankaj Kushwaha
Universe 2025, 11(3), 84; https://doi.org/10.3390/universe11030084 - 5 Mar 2025
Viewed by 438
Abstract
The X-ray spectrum of OJ 287 has exhibited diverse variations with broadband spectral behavior representative of all the spectral classes of blazars. These changes have been explained either via new emission components or as the sum of the jet synchrotron and its inverse [...] Read more.
The X-ray spectrum of OJ 287 has exhibited diverse variations with broadband spectral behavior representative of all the spectral classes of blazars. These changes have been explained either via new emission components or as the sum of the jet synchrotron and its inverse Compton part. In the current work, we focus on the systematic spectral investigation of the lowest X-ray state recorded by the Swift facility to understand X-ray spectral changes. Considering optical-to-X-ray observations jointly, we found a power-law optical–UV spectrum with a photon spectrum of 2.71 ± 0.03 extending to X-ray energies. Accounting for this contribution in X-rays, we inferred a power-law photon X-ray spectrum of 1.22 ± 0.20 that improves to 1.29 ± 0.06 when considering other observations with similar X-ray spectra. An extended optical–UV spectrum with an associated low hard X-ray spectrum is further strengthened by the natural explanation of another optical–UV state of similar flux with a very different optical–UV-to-X-ray spectrum by its synchrotron and this hard X-ray spectrum. This is the hardest reported X-ray spectrum (0.3–10 keV), consistent with the Swift-BAT X-ray spectrum. We further found that this X-ray spectrum can reproduce most of the flat X-ray spectra when combined with the corresponding optical–UV continuum during the low and intermediate flux states, strengthening the synchrotron as the primary driver of most of the X-ray spectral changes in the LBL state of the source. Compared with the sharp steepening/cutoff of the optical–UV spectrum during bright phases, the inferred extended spectrum implies a comparatively larger emission region and could be associated with large-scale jet emission. The optical–UV spectrum implies a high-energy power-law particle spectrum of ∼4.4, while X-ray implies a hard low-energy particle spectrum of 1.3–1.6 that alternatively can also result from a higher lower-energy cutoff in the particle spectrum. Full article
(This article belongs to the Special Issue Universe: Feature Papers 2025—Space Science)
►▼ Show Figures

Figure 1

13 pages, 2913 KiB  
Article
Low-Latitude Ionospheric and Geomagnetic Disturbances Caused by the X7.13 Solar Flare of 25 February 2014
by Zane Nikia C. Domingo, Ernest P. Macalalad and Akimasa Yoshikawa
Universe 2025, 11(2), 70; https://doi.org/10.3390/universe11020070 - 17 Feb 2025
Viewed by 515
Abstract
On 25 February 2014 at around 00:39 UT, a major solar flare (code: SOL2014-02-25T00:39) erupted at sunspot region AR11990. Using the updated science quality data of GOES-15, it has been classified as an X7.13 solar flare. This gave rise to the electron density [...] Read more.
On 25 February 2014 at around 00:39 UT, a major solar flare (code: SOL2014-02-25T00:39) erupted at sunspot region AR11990. Using the updated science quality data of GOES-15, it has been classified as an X7.13 solar flare. This gave rise to the electron density changes that affected the strengths of ionospheric electric currents. In this work, the difference in total electron content (TEC), between the TEC during a flare day and a quiet, fitted TEC, ΔTEC, and rate of change of TEC, dTEC/dt, are determined to observe electron density changes due to the solar flare over a low-latitude region. These stations are at Quezon City (PIMO) and Taguig City (PTAG). Also, responses in the geomagnetic field component, ΔH, are calculated along with the variations in the equatorial electrojet (EEJ) strength. These are observed at equatorial, Davao (DAV) and Cagayan de Oro (CDO), and off-equatorial, Muntinlupa (MUT) and Legazpi (LGZ), stations. The resulting ΔTEC values were 1.17–1.97 TECU while dTEC/dt maxima were 0.29–0.48 TECU/min. The dTEC/dt maxima were found to concur with the time the solar EUV reached peak intensity at 00:45 UT, 4 min before the flare (i.e., X-ray) peaked. Furthermore, the ΔH variations exhibited larger enhancements at the equatorial stations. These are mostly attributed to the EEJ contributing to the geomagnetic field variations. The amplification experienced by the EEJ due to the increased ionospheric conductivity is then reflected in the geomagnetic responses. For the CDO-LGZ stations, the EEJ strength reached ~37 nT, while for the DAV-MUT, this was ~60 nT. Full article
(This article belongs to the Special Issue Universe: Feature Papers 2025—Space Science)
►▼ Show Figures

Figure 1

13 pages, 5350 KiB  
Article
Cosmic Ray Spectra and Anisotropy in an Anisotropic Propagation Model with Spiral Galactic Sources
by Aifeng Li, Zhaodong Lv, Wei Liu, Yiqing Guo and Fangheng Zhang
Universe 2025, 11(2), 53; https://doi.org/10.3390/universe11020053 - 7 Feb 2025
Viewed by 540
Abstract
In our previous work, we investigated the spectra and anisotropy of galactic cosmic rays (GCRs) under the assumption of an axisymmetric distribution of galactic sources. Currently, much observational evidence indicates that the Milky Way is a typical spiral galaxy. In this work, we [...] Read more.
In our previous work, we investigated the spectra and anisotropy of galactic cosmic rays (GCRs) under the assumption of an axisymmetric distribution of galactic sources. Currently, much observational evidence indicates that the Milky Way is a typical spiral galaxy. In this work, we further utilize an anisotropic propagation model under the framework of spiral distribution sources to study spectra and anisotropy. During the calculation process, we adopt the spatial-dependent propagation (SDP) model, while incorporating the contribution from the nearby Geminga source and the anisotropic diffusion of cosmic rays (CRs) induced by the local regular magnetic field (LRMF). By comparing the results of background sources with spiral and axisymmetric distribution models, it is found that both of them can well reproduce the CR spectra and anisotropy. However, there exist differences in their propagation parameters. The diffusion coefficient with spiral distribution is larger than that with axisymmetric distribution, and its spectral indices are slightly harder. To investigate the effects of a nearby Geminga source and LRMF on anisotropy, two-dimensional (2D) anisotropy sky maps under various contributing factors are compared. Below 100 TeV, the anisotropy is predominantly influenced by both the nearby Geminga source and the LRMF, causing the phase to align with the direction of the LRMF. Above 100 TeV, the background sources become dominant, resulting in the phase pointing towards the Galactic Center (GC). Future high-precision measurements of CR anisotropy and spectra, such as the LHAASO experiment, will be crucial in evaluating the validity of our proposed model. Full article
(This article belongs to the Special Issue Universe: Feature Papers 2025—Space Science)
►▼ Show Figures

Figure 1

Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:
 
Displaying articles 1-6
Back to TopTop