Research Interests


NuSTAR is the first focusing hard X-ray satellite in orbit, providing more than two orders of magnitude improvement in sensitivity as compared to previous high-energy missions working at similar energies. The primary science goals of NuSTAR are broad, and include studying a range of high-energy sources, including black holes, supernovae explosions, neutron stars, relativistic jets, and the Sun.

Accreting Compact Objects

Accreting compact objects, such as black holes and neutron stars bend and twist space-time, or contain degenerate matter with unique properties. We use X-ray telescopes like NuSTAR (among others) to observe the high-energy emission from these objects in binary systems, in which the compact object is gravitationally tied to a stellar companion.


Ultraluminous X-ray Sources (ULXs) are X-ray binaries in other galaxies undergoing such extreme accretion that they are some of the most luminous X-ray sources in the nearby Universe outside of the centers of galaxies.

More Research!

There's a whole lot more for NuSTAR to look at beyond accreting compact objects and ULXs alone! Click below to hear about some more of the fascinating topics that our team devote their time to exploring.

Group Members

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Upcoming and Recent Group Activity

  • Jan 20

    Summer undergraduate research opportunities in the HEA Group

    Do you want to spend a summer doing research in the HEA Group? Caltech offers the Summer Undergraduate Research Fellowships (SURF) program which gives undergraduate students the opportunity to conduct research under the guidance of experienced mentors working at the frontier of their fields. Check here for opportunities, including in the HEA Group.

  • Jan 12

    The HEA Group attends AAS 241

    Several members of the HEA Group including Amruta, Dan, Ed, Javier, Hannah, Karl, Margaret, Murray, Peter and Yuhan traveled to Seattle to attend the 241st Meeting of the American Astronomical Society (AAS 241). There they presented their work through talks, iposters and press conferences, and met with colleagues old and new.

  • Dec 20

    Yuhan's work is highlighted in a JPL press release

    Graduate student Yuhan Yao’s results on the tidal disruption event AT2021ehb were highlighted in a JPL press release. Congratulations Yuhan!

  • Dec 15

    Peter gives a talk at the Torus 2022 workshop

    Postdoc Peter Boorman gave a talk on the NuSTAR Local AGN NH Distribution Survey (NuLANDS) at the TORUS 2022 workshop in Leiden in the Netherlands. The conference discussed the latest in modelling and observations of the circum-nuclear region surrounding AGN, as well as plans for future ground-and space-based missions.

  • Dec 14

    Yuhan gets NICER Cycle 5 observations

    Graduate student Yuhan Yao has been awarded observations with NASA's Neutron Star Interior Composition Explorer Mission (NICER) in their Cycle 5 call for proposals. She proposed for NICER+NuSTAR observations of two tidal disruption events. Congratulations Yuhan!

  • Dec 7

    Fiona gives a talk at the University of Michigan

    NuSTAR PI and HEA Group leader Professor Fiona Harrison traveled to Ann Arbor, Michigan this week to give the Mohler Prize lecture on The Science of NuSTAR.

  • Dec 6

    Brian and Hiro's paper is published

    NuSTAR Scientists Brian Grefenstette and Hiro Miyasaka have a new paper out in the Journal of Astronomical Telescopes, Instruments, and Systems (JATIS) describing the NuSTAR background.

  • Dec 2

    The HEA Group gets a visit from Dr. Mike Koss of Eurika Scientific

    Friend of the HEA Group Mike Koss visited this week and have a presentation on his work on NuSTAR observations of Swift/BAT selected AGN.

  • Nov 30

    Yuhan's work is published in Nature

    Graduate student Yuhan Yao was involved in a study of the tidal disruption event AT 2022cmc that was published in Nature this week. Congratulations Yuhan!

  • Nov 14

    Amruta travels to Texas and Michigan to talk about her work

    This week postdoc Amruta Jaodand presented her latest work on the discovery of UV millisecond pulsations in transitional millisecond pulsars in a colloquium at the University of Texas Rio Grande Valley and a seminar at Wayne State University. She also spoke with PhD and undergraduate students and advised them on applying for postdocs including in the HEA group.

  • Nov 14

    Margaret goes observing to Keck on the Big Island of Hawaii

    This week postdoc Margaret Lazzarini went to Hawaii to observe on the Keck Telescopes. She used the DEIMOS spectrograph on Keck II to get optical spectra of companion stars in high mass X-ray binary systems in nearby galaxies Andromeda (M31) and Triangulum (M33).

  • Nov 2

    Murray gets follow-up observations of the X-ray transient he found

    Staff Scientist Murray Brightman got observations of the new X-ray source he found in the galaxy NGC 7793 with Swift, NuSTAR and Chandra which revealed it to be a new ultraluminous X-ray source. He reported on it in an Astronomer's Telegram.

  • Oct 31

    Dr. Ed Nathan joins the HEA Group

    Ed joins us from Oxford University in the UK as a postdoctoral researcher. Welcome Ed!

  • Oct 14

    Dr. Peter Boorman joins the HEA Group

    Peter joins us from Czech Academy of Sciences in Czechia as a postdoctoral researcher. Welcome Peter!

  • Oct 6

    Hannah gives a talk to science educators

    Staff Scientist Hannah Earnshaw gave a talk about NuSTAR to NASA's Universe of Learning to celebrate 10 years of NuSTAR!

  • Sep 26

    Murray finds an X-ray transient in a nearby galaxy

    Staff Scientist Murray Brightman found a new X-ray source in the galaxy NGC 7793 that had never been detected before. He reported on it in an Astronomer's Telegram.

  • Aug 31

    Dr. Oluwashina (Shina) Adegoke joins the HEA Group

    Shina joins us from Afe Babalola University in Nigeria as a postdoctoral researcher. Welcome Shina!

  • Aug 24

    Gullo's paper is accepted for publication!

    Postdoc Gullo Mastroserio's paper on the high energy X-ray spectrum of Cyg X-1 with NuSTAR stray light and INTEGRAL has been accepted for publication in ApJ. Congratulations Gullo!

  • Aug 18

    Summer Seminar Day

    Summer Seminar Day marks the end of the project for most of our Summer Undergraduate Research Fellows. Our SURFs gave excellent poster and oral presentations of their final projects. Thank you for a wonderful summer of science, SURFs, and best of luck with your next year of school!

  • Aug 4

    Amruta does virtual science outreach

    Postdoc Amruta Jaodand is passionate about promoting science with a focus on inspiring students from diverse, traditionally under-represented background. She has presented many public lectures, organised star gazing nights and for the last two years has been dedicating time to visit schools virtually or in person through Skype a Scientist Initiative. This week she 'visited' a school in Wandin, Australia to talk about various topics such as pulsars, space telescopes such as NuSTAR and growing need for coding and computational resources in astronomy analysis. There were 2 classroom of very excited students in age groups of 10-14. The virtual Q&A after talk lasted almost an hour, and ended with the students giving the 'Live Long and Prosper' sign.

  • July 20

    Brian gives public lecture

    Staff scientist Brian Grefenstette gave a public lecture to the Night Sky Network about NuSTAR and the exciting X-ray science it has covered in its 10 years of operation. Read more about the talk and watch the recording here!

  • July 18

    Sean successfully defends his Ph.D. thesis!

    Graduate student Sean Pike successfully defended his Ph.D. thesis. Congratulations Dr. Pike!

  • July 14

    Riley's paper is accepted for publication!

    Postdoc Riley Connors' paper, titled "The long-stable hard state of XTE J1752-223 and the disk truncation dilemma," has been accepted for publication in ApJ. You can read the full paper here. Congratulations Riley!

  • July 8

    Margaret's paper is accepted for publication!

    Postdoc Margaret Lazzarini's paper on measuring the star formation history in the Triangulum Galaxy has been accepted for publication in ApJ. You can read the full paper here, or check out the awesome Astrobites article on the paper instead! Congratulations Margaret!

  • July 7

    Renee's paper is accepted for publication!

    Postdoc Renee Ludlam's paper, titled " StrayCats II: An Updated Catalog of NuSTAR Stray Light Observations," has been accepted for publication in ApJ. You can read the full paper here, and learn more about the StrayCats project on their website! Congratulations Renee!