High-Energy Astrophysics Research Enabled By The Probe-Class Mission Concept HEX-P

About this Research Topic

Background

The Astro 2020 Decadal report (Pathways to Discovery in Astronomy and Astrophysics for the 2020s) identified the need for a new class of mission for the next decade that fills the gap between a Mid-sized Explorer (MIDEX) and Flagship (Large) mission. The report specifically recommends that a cadence of one probe mission per decade with a cost cap of $1.5 billion balances scientific scope with timeliness. NASA has followed this recommendation and opened a call for Astrophysics Probe Explorer (APEX) proposals, restricted to either a far-infrared or an X-ray mission, due in Fall 2023 with a planned launch date in no later than 2032.

In response to this call, the High-Energy X-ray Probe (HEX-P) concept has been developed as a partnership between NASA’s Jet Propulsion Laboratory (JPL), the California Institute of Technology (Caltech), and the NASA Goddard Space Flight Center (GSFC), with international partnership from the Italian Space Agency (ASI; Italy), the German Space Agency (DLR), and the Max Planck Institute for Extraterrestrial Physics (MPE; Germany). HEX-P is a mission concept that offers sensitive broad-band coverage from soft to hard X-rays (0.2 − 80 keV), with an exceptional combination of spectral, timing, and angular capabilities. It features two high-energy telescopes (HETs) that focus hard X-rays, and one low-energy telescope (LET) that focuses lower energy X-rays, building upon the heritage of previous successful missions such as XMM-Newton and NuSTAR.

With this leap in observational capability, HEX-P will be capable of addressing fundamental questions about the extreme environments around black holes and neutron stars, map the growth of supermassive black holes, and quantify the effect they have on their environments. HEX-P will resolve the hard X-ray emission from dense regions of our Galaxy to understand the high-energy source populations and investigate dark matter candidate particles through their decay channel signatures.

In this Frontiers Research Topic we present a collection of papers which delve into some of the most exciting scientific questions that can be addressed with a mission like HEX-P. The papers have been prepared by members of the HEX-P collaboration, which is organized into four main scientific pillars:

• Black Hole Growth
• Accretion Power
• Stellar Evolution
• Time-Domain and Multi-Messenger Astronomy

The individual papers cover a range of topics, including:

• The cosmic X-ray background
• Seyfert galaxies, Compton-thick active galaxies, and blazars
• Black hole binaries, neutron stars, magnetars, ultraluminous X-ray sources, and tidal disruption events
• The physics of the X-ray corona
• X-ray populations in nearby galaxies
• Supernova remnants, pulsar wind nebulae, and nuclear astrophysics
• Galactic PeVatrons, star clusters, superbubbles, microquasar jets, and gamma-ray binaries
• The Galactic Center
• Supermassive black spin measurements and dual active galaxies
• Pulsar Timing, electromagnetic counterparts of gravitational wave sources and transient phenomena

The main goal of this Research Topic is to present detailed modeling and simulations for a range of HEX-P science cases in order to demonstrate the capabilities of HEX-P in serving the astrophysics community in the next decade.

The members of the HEX-P mission are welcome to present Original Research papers, as well as any other kind of article types that fit their manuscript. Please, have a look at here to choose the appropriate article type to submit to this collection.


This Research Topic is organized by the researchers of the HEX-P mission. Authors and Guest Editors belong to the same consortium. Furthermore, Dr. Daniel Stern and Dr. Javier Garcia are the Principal Investigator and the Project Scientist of the mission respectively. All manuscripts will be peer-reviewed by researchers external to the collaboration.

Keywords: HEX-P, black hole, accretion power, stellar evolution, time-domain astronomy, multi-messenger astronomy

Important note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.

Frequently asked questions

• What is a Research Topic?

  Frontiers' Research Topics are collaborative hubs built around an emerging theme.Defined, managed, and led by renowned researchers, they bring communities together around a shared area of interest to stimulate collaboration and innovation.

  Unlike section journals, which serve established specialty communities, Research Topics are pioneer hubs, responding to the evolving scientific landscape and catering to new communities.

• Why does Frontiers publish Research Topics? 

  The goal of Frontiers' publishing program is to empower research communities to actively steer the course of scientific publishing. Our program was implemented as a three-part unit with fixed field journals, flexible specialty sections, and dynamically emerging Research Topics, connecting communities of different sizes and maturity.

  Research Topics originate from the scientific community. Many of our Research Topics are suggested by existing editorial board members who have identified critical challenges or areas of interest in their field.

• Why are Research Topics important for journals?

  As an editor, Research Topics will help you build your journal, as well as your community, around emerging, cutting-edge research. As research trailblazers, Research Topics attract high-quality submissions from leading experts all over the world.

  A thriving Research Topic can potentially evolve into a new specialty section if there is sustained interest and a growing community around it.

• How do we ensure the quality of articles within Research Topics?

  Each Research Topic must be approved by the specialty chief editor, and it falls under the editorial oversight of our editorial boards, supported by our in-house research integrity team. The same standards and rigorous peer review processes apply to articles published as part of a Research Topic as for any other article we publish.

  In 2023, 80% of the Research Topics we published were edited or co-edited by our editorial board members, who are already familiar with their journal's scope, ethos, and publishing model. All other topics are guest edited by leaders in their field, each vetted and formally approved by the specialty chief editor.

• What are the benefits of publishing my article in a Research Topic?

  Publishing your article within a Research Topic with other related articles increases its discoverability and visibility, which can lead to more views, downloads, and citations. Research Topics grow dynamically as more published articles are added, causing frequent revisiting, and further visibility.

  As Research Topics are multidisciplinary, they are cross-listed in several fields and section journals – increasing your reach even more and giving you the chance to expand your network and collaborate with researchers in different fields, all focusing on expanding knowledge around the same important topic.

  Our larger Research Topics are also converted into ebooks and receive social media promotion from our digital marketing team.

   
• What types of articles can be published in a Research Topic?

  Frontiers offers multiple article types, but it will depend on the field and section journals in which the Research Topic will be featured. The available article types for a Research Topic will appear in the drop-down menu during the submission process.

  Check available article types here 

• Can I suggest a new Research Topic? 

  Yes, we would love to hear your ideas for a topic. Most of our Research Topics are community-led and suggested by researchers in the field. Our in-house editorial team will contact you to talk about your idea and whether you’d like to edit the topic. If you’re an early-stage researcher, we will offer you the opportunity to coordinate your topic, with the support of a senior researcher as the topic editor. 

  Suggest your topic here 

• Who leads a Research Topic? 

  A team of guest editors (called topic editors) lead their Research Topic. This editorial team oversees the entire process, from the initial topic proposal to calls for participation, the peer review, and final publications.

  The team may also include topic coordinators, who help the topic editors send calls for participation, liaise with topic editors on abstracts, and support contributing authors. In some cases, they can also be assigned as reviewers.

• What is the role of a topic editor?

  As a topic editor (TE), you will take the lead on all editorial decisions for the Research Topic, starting with defining its scope. This allows you to curate research around a topic that interests you, bring together different perspectives from leading researchers across different fields and shape the future of your field. 

   

  You will choose your team of co-editors, curate a list of potential authors, send calls for participation and oversee the peer review process, accepting or recommending rejection for each manuscript submitted.

• What support will I receive when editing a new Research Topic? 

  As a topic editor, you're supported at every stage by our in-house team. You will be assigned a single point of contact to help you on both editorial and technical matters. Your topic is managed through our user-friendly online platform, and the peer review process is supported by our industry-first AI review assistant (AIRA).

• As a junior researcher, can I be involved in editing a Research Topic? 

  If you’re an early-stage researcher, we will offer you the opportunity to coordinate your topic, with the support of a senior researcher as the topic editor. This provides you with valuable editorial experience, improving your ability to critically evaluate research articles and enhancing your understanding of the quality standards and requirements for scientific publishing, as well as the opportunity to discover new research in your field, and expand your professional network.

• Can I get a certificate for editing a Research Topic?

  Yes, certificates can be issued on request. We are happy to provide a certificate for your contribution to editing a successful Research Topic.

• Who will I collaborate with?

  Research Topics thrive on collaboration and their multi-disciplinary approach around emerging, cutting-edge themes, attract leading researchers from all over the world.

• How long does it take to publish a Research Topic?

  As a topic editor, you can set the timeline for your Research Topic, and we will work with you at your pace. Typically, Research Topics are online and open for submissions within a few weeks and remain open for participation for 6 – 12 months. Individual articles within a Research Topic are published as soon as they are ready.

  Find out more about our Research Topics

• What fee support is available to authors publishing in a Research Topic?

  Our fee support program ensures that all articles that pass peer review, including those published in Research Topics, can benefit from open access – regardless of the author's field or funding situation.

  Authors and institutions with insufficient funding can apply for a discount on their publishing fees. A fee support application form is available on our website.

• Will there be a printed version of my Research Topic?

  In line with our mission to promote healthy lives on a healthy planet, we do not provide printed materials. All our articles and ebooks are available under a CC-BY license, so you can share and print copies.