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

  • May 29

    Margaret's paper on high mass X-ray binaries in M33 was accepted for publication

    Postdoctoral fellow Margaret Lazzarini's paper on the high mass X-ray binary population of nearby galaxy M33 was accepted for publication in the Astrophysical Journal. Congratulations Margaret!

  • May 22

    Yuhan defends her thesis!

    Graduate student Yuhan Yao successfully defended her PhD thesis entitled “High Energy Transients Powered by Black Holes”. In August, she will start a Miller fellowship at UC Berkeley. Congratulations Yuhan!

  • May 19

    NuSTAR detects hard X-rays from a nearby supernova

    The closest supernova in a decade, SN 2023ixf, was found in the Pinwheel galaxy (M101) and is thought to have been produced by the collapse of a massive star. Telescopes all over the world, and in space, rushed to observe this rare event. Staff Scientist Brian Grefenstette organised for NuSTAR to observe it, and reported on the detection of hard X-rays in an Astronomer's Telegram

  • May 12

    Peter gives a talk to an Astronomy Club

    Peter Boorman gave a lecture to the Antelope Valley Astronomy Club in Palmdale. The talk overviewed the history of X-ray astronomy, and the different multi-wavelength techniques available today to identify and study accreting supermassive black holes observationally. The talk also presented some of the exciting research highlights from the past ~11 years of NuSTAR operation and the prospects on the horizon with the High Energy X-ray Probe mission concept.

  • May 4

    Murray's paper on transient ULXs was accepted for publication

    Staff Scientist Murray Brightman's paper on a new sample of transient ultraluminous X-ray sources he found was accepted for publication by the Astrophysical Journal. Congratulations Murray!

  • May 1

    Dr. Asia (Joanna) Piotrowska joins the HEA Group

    Asia joins us from Cambridge University in the UK as a postdoctoral researcher. Welcome Asia!

  • Apr 29

    HEA Group members volunteer at Explore JPL

    NASA's Jet Propulsion Laboratory held their annual open house event, Explore JPL, which is a chance for visitors to to learn more about space exploration, robotics, and technology being developed. HEA Group members Ed, Lynnie, Peter and Shina took part to share their knowledge on NuSTAR and black holes.

  • Apr 24

    Karl attends IACHEC

    NuSTAR Science Operations Manager, Karl Forster, attended the 15th meeting of the International Astronomical Consortium for High-Energy Calibration (IACHEC) in Pelham, Germany. These annual meetings bring together calibration teams from all the high-energy astrophysics missions in operation, development and those being planned. The years of experience of the IACHEC members has helped with the calibration of many missions, including NuSTAR, and these annual working meetings provide a forum for the community to discuss and coordinate calibration activities.

  • Apr 17

    NuSTAR Cycle 9 results are out!

    The results from the NuSTAR Cycle 9 peer review have now been published. Among the successful proposers were HEA Group members Amruta, Javier, Peter and Shina. Congratulations!

  • Apr 14

    Peter gives a seminar at Wayne State University

    Postdoc Peter Boorman gave seminar at Wayne State University on the NuSTAR Local AGN NH Distribution Survey (NuLANDS).

  • Apr 10

    Labani gives a seminar at CSU Stanislaus

    Postdoc Labani Mallik visited California State University, Stanislaus this week and gave an invited seminar. The title of her talk was "Accreting Massive Black Holes at the Center of Galaxies and their Impacts on Small and Large Scales."

  • Apr 6

    Matteo's result is highlighted in a JPL press release

    Former HEA Group member Matteo Bachetti's work on the orbital decay of the ultraluminous X-ray pulsar powering M82 X-2 was highlighted in a JPL press release. His result confirmed that the pulsar is intrinsically as bright as it appears, and is not a result of the emission being beamed in our direction. Congratulations Matteo!

  • Mar 26

    The HEA Group travels to Hawaii for HEAD 20

    The 20th Meeting of the High Energy Astrophysics Division of the AAS will take place on the Big Island of Hawaii, March 26-30. Many members of the HEA Group will be in attendence to present their work on ultraluminous X-ray sources, X-ray binaries and active galactic nuclei. There will also be a special session on X-ray probe concepts, including the High Energy X-ray Probe (HEX-P) lead by NuSTAR Project Scientist Daniel Stern.

  • Mar 15

    Caltech hosts the First UVEX Community Workshop

    This week Caltech hosted the First UVEX Community Workshop: Synergies and New Opportunities. Astronomers from all over the US and abroad came to hear and talk about Gravitational Wave astronomy, stars, galaxies, dust and time domain astronomy in the UV.

  • Mar 12

    Labani gets a CITA National Fellowship

    Postdoc Labani Mallick was offered and accepted a CITA National Fellowship. She will conduct independent research on high-energy astrophysics at the University of Manitoba under the CITA National Fellowship program.

  • Feb 27

    McKinley becomes a professor

    Former postdoc McKinley Brumback has accepted a tenure-track position as Assistant Professor of Physics at Middlebury College in Middlebury, Vermont, beginning in July 2023. In her new role, Professor Brumback will teach physics core curriculum, mentor undergraduates in high energy astrophysics research, and help the Middlebury Physics Department expand its offered astronomy curriculum. Congratulations McKinley!

  • Feb 15

    The HEA Group gets a visit from Professor Adlyka Annuar

    Professor Adlyka (Ady) Annuar is currently visiting the HEA Group from the National University of Malaysia. She is visiting for a month to work on a sample of local AGN mainly using NuSTAR and Chandra data. Welcome Ady!

  • Feb 13

    Peter gives a talk at Astronomy on Tap

    Postdoc Peter Boorman presented his research at Astronomy on Tap about finding accreting supermassive black holes. Astronomy on Tap is a regular nation-wide event in which astronomers present their research in an informal setting at local bars. For more details of future events in Pasadena, see the webpage here.

  • Feb 10

    Swift Cycle 19 results are out

    The results from the Swift Cycle 19 peer review have now been published. Among the successful proposers is NuSTAR Project Scientist Daniel Stern, who has been awarded time to observe the potential electromagnetic counterparts from black hole mergers in the accretion disks of AGN. Congratulations Dan!

  • Feb 9

    NuSTAR observations of the Sun highlighted in a JPL press release

    This week JPL highlighted observations of the Sun made by NuSTAR in a press release. NuSTAR observed the Sun at the same time the X-ray Telescope (XRT) on the Japanese Aerospace Exploration Agency’s Hinode mission and and the Atmospheric Imaging Assembly (AIA) on NASA’s Solar Dynamics Observatory. These observations occurred in June 2022 during the perihelion pass of the Parker Solar Probe, which enables scientists to link activity observed remotely in the Sun’s atmosphere with the direct samples of the solar environment taken by the probe.

  • Feb 3

    Peter gives a tutorial on Bayesian X-ray spectral fitting

    Postdoc Peter Boorman visited the University of Clemson to present a colloquium and give a tutorial on Bayesian X-ray spectral fitting. Bayesian spectral analysis is useful for systematic fitting with minimal user input of initial parameters, efficient systematic fitting of large datasets with many sources or comparing many models and provides accurate parameter constraints, even for (very) low counts or for complex parameter spaces with strong degeneracies.

  • Jan 30

    Caltech to host the First UVEX Community Workshop

    On March 13-15, 2023, Caltech will be hosting the First UVEX Community Workshop: Synergies and New Opportunities, to explore the potential science opportunities presented by the Ultraviolet Explorer, a proposed MIDEX mission currently in Phase A of development and led by Professor Fiona Harrison. For more information and to register, see here.

  • Jan 26

    NuSTAR Cycle 9 proposals submitted

    The deadline for NuSTAR Cycle 9 proposals was on January 26th and many members of the HEA Group made submissions to have their targets observed. Successful proposals will be selected by an anonymous review panel and observations will start in June 2023. Good luck to everyone who submitted a proposal!

  • Jan 23

    Renee wins the 2023 Newton Lacy Pierce Prize

    Former postdoc Renee Ludlam is the recipient of the American Astronomical Society's (AAS) 2023 Newton Lacy Pierce Prize. The prize is awarded for outstanding achievement in observational astronomical research based on measurements of radiation from an astronomical object. Renee won for her novel explorations of the relativistic universe that have revealed fundamental properties of neutron stars. Congratulations Renee!

  • 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

    Hannah goes observing to Hawaii

    Staff Scientist Hannah Earnshaw went to Hawaii to use the near infrared camera NIRC2 on the Keck telescope to look for infrared counterparts to ultraluminous X-ray sources in nearby galaxies. The laser guide star system on Keck allows for taking very high-resolution images, which they will use to find out which exact star is the companion to the X-ray source.

  • 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.

  • Jan 9

    Aria get a Posse Scholarship

    Aria Gasca, a high school student who worked with Margaret Lazzarini as part of the Hybrid Summer Research Connections program in the summer of 2022, was recently awarded a prestigious Posse Scholarship to attend Tulane University next year. Aria worked on a research project combining NuSTAR, Chandra, and Hubble observations of the nearby galaxy Triangulum to identify optical counterparts to hard X-ray sources in the galaxy.

  • 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.