Home of the Caltech NuSTAR Science Team
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.
UVEX is a new NASA Medium Explorer mission to explore the ultraviolet sky, with an expected launch date in 2030. With a wide-field, two-band ultraviolet imager and long, multi-width slit spectrometer, UVEX will address outstanding questions in our understanding of the Universe, including the nature of the low-mass, low-metallicity galaxy population and the early ultraviolet emission of explosive transients. UVEX will also leave a rich legacy of all-sky ultraviolet data.
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.
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.
Postdoc Peter Boorman's latest paper entitled "XMM-Newton Conclusively Identifies an Active Galactic Nucleus in a Green Pea Galaxy" has been accepted for publication by The Astrophysical Journal. In it Peter analyzes data on a relatively nearby low-mass, low-metallicity star-forming galaxy, known as a "Green Pea galaxy" because of its color, similar to the types of galaxies expected in the early Universe. He finds that the X-ray emission coming from this galaxy must be from an accreting supermassive black hole, which has not previously been found for this kind of galaxy. Congratulations Peter!
Postdoc Elias Kammoun's latest paper has been published in the journal Astronomy & Astrophysics. In this paper, he explored the origin of the tight UV-to-X-ray correlation seen in quasars, from the lens of X-ray illumination of accretion disks. He found that this model can indeed explain the observed correlation by implying a correlation between the black hole mass, the accretion rate, and the coronal power, which can shed light on the evolution of black holes in quasars and the physics regulating the X-ray corona. Congratulations Elias!
The results of the NuSTAR Cycle 11 review have been released. Among the successful proposers were group members Murray, Xiurui, Peter and Lea as well as former members Dom, Matteo and Ed. The group members will use NuSTAR to study transient ultraluminous X-ray sources, the AGN corona, a 'green pea' galaxy, Galactic Gamma-ray sources, a flaring extragalactic very high energy Gamma-ray source and more! Congratulations all!
Staff scientist Murray Brightman traveled to Florence, Italy to take part in the Celebrating 20 years of Swift Discoveries meeting. When the Neil Gehrels Swift Observatory was launched on November 20, 2004, its prime objective was to chase Gamma-Ray Bursts. Since then, the mission has far exceeded its original scientific goals. Murray gave a talk on his discovery of transient ultraluminous X-ray sources using Swift data.
Demet joins us from the University of British Columbia in Canada, read her bio here. Welcome Demet!
Postdocs Shina Adegoke, Peter Boorman and Ed Nathan traveled to conferences this month. Shina and Ed went to Tempe, Arizona for the XRISM science meeting where they presented their work on high resolution X-ray spectroscopy. Peter went to Jukkasjärvi, Sweden for the Beyond the Curtain of Dust V meeting where he spoke about his work on heavily obscured active galactic nuclei.
Several members of the HEA Group traveled to Maryland to attend the 245th Meeting of the American Astronomical Society (AAS 245) and postdocs Peter Boorman and Lea Marcotulli talked to the press about their recent results. Peter presented his results investigating how commonly growing supermassive black holes are obscured by intervening gas and dust in a press release entitled "How Many Black Holes Are Hiding? NASA Study Homes in on Answer". Lea presented her paper on her investigation into a growing supermassive black hole in the early universe and was entitled "This quasar may have helped turn the lights on for the universe". Peter's press briefing video can be seen here and Lea's can be found here.
The HEA group is offering up to 4 SURF opportunities for the summer of 2025. The SURF projects on offer will be in all group research areas and be mentored by the staff scientists and postdocs of the group. Caltech students will be prioritized, however we welcome applications from other universities and will consider them once Caltech students have been taken care of. Interested students should email heag[at]caltech[dot]edu listing which areas of HEAG research they are most interested in and which mentors they are most interested in working with, listed by preference, and a CV. We expect to carry out interviews with prospective candidates by the end of January/beginning of February in preparation for the SURF application deadline on February 22, 2025. The HEAG also welcomes WAVE students which has a separate application procedure. These are due January 10, 2025.
The results of XMM-Newton's Cycle 24 proposals have been released. Among the successful proposals were those of postdocs Peter Boorman and Lea Marcotulli. Peter will observe the galaxy ESO495-5 with XMM-Newton and NuSTAR to investigate why it is faint in X-rays, which could be due to a high accretion rate or high levels of obscuration. Lea will observe 5 candidate gamma-ray sources in our Galaxy to determine if they could be supernova remnants, pulsars, or pulsar wind nebulae. Congratulations Peter and Lea!
Postdoc Asia Piotrowska gave a talk on AI in astrophysics at the SMASH Initiative (UC San Diego Meetings between Astro/physics, SDSC, & HDSI) at UC San Diego. She was also invited to give the Astronomy & Cosmology Seminar at UCSD on November 4th, and was invited to give the Astronomy & Physics colloquium at UC Irvine on October 10th. Nice work Asia!
Postdoc Xiurui Zhao's paper An X-Ray Significantly Variable, Luminous, Type 2 Quasar at z = 2.99 with a Massive Host Galaxy has been published in the Astrophysical Journal. In it he describes his investigation into a very massive galaxy that is both forming stars at a high rate as well as hosting a rapidly growing supermassive black hole in its center, using NuSTAR data in his analysis. Congratulations Xiurui!
Postdoc Peter Boorman had a good week having two papers accepted for publication. The first is entitled The NuSTAR Local AGN NH Distribution Survey (NuLANDS) I: Towards a Truly Representative Column Density Distribution in the Local Universe and describes how commonly growing supermassive black holes are obscured by intervening gas and dust close to the black hole. The second is entitled An Intermediate Mass Black Hole Hidden Behind Thick Obscuration where Peter and collaborators study an example of a relatively rare class of intermediate-mass black hole, finding it too is heavily obscured by gas close to it. Both studies used the capabilities of NuSTAR to characterise the high-energy X-rays that can pass through these layers of gas, and both papers will appear in the Astrophysical Journal. Congratulations Peter!
Postdoc Shina Adegoke's paper entitled Characterizing the Broadband Reflection Spectrum of MAXI J1803-298 During its 2021 Outburst with NuSTAR and NICER was recently accepted for publication by the Astrophysical Journal. In it he reported on his analysis of NuSTAR and NICER observations of a black hole binary where he was able to measure the spin of the black hole and find evidence for absorption by ionized gas. Congratulations Shina!
One Friday night a month, Caltech Astronomy hosts a free public lecture on astronomy and space science given by a member of the department followed by guided stargazing with telescopes. On September 27th, postdoc Asia Piotrowska gave one of these lectures entitled "Artificial Intelligence in Astrophysics". She talked about how the advent of artificial intelligence and machine learning is changing astrophysics and what new astronomical discoveries will be possible with these exciting technologies. The event was recorded and can be viewed on YouTube!
Postdoc Peter Boorman visited the Green Bank Observatory in West Virginia. Peter gave a colloquium entitled "Understanding the Dining Habits of Supermassive Black Holes", in which he described the various ways astronomers try to understand the growth of supermassive black holes in as unbiased a way as possible.
The list of approved targets for Chandra's Cycle 26 have been posted and Staff Scientist Murray Brightman was awarded a target of opportunity observation to observe a transient X-ray source identified in Swift/XRT observations. Congratulations Murray!
Elias joins us from Università Roma Tre in Italy. Welcome Elias!
Postdoc Ed Nathan's paper entitled Proof of principle X-ray reflection mass measurement of the black hole in H1743-322 has been published in the Monthly Notices of the Royal Astronomical Society. He modeled the X-ray emission from a black hole in our Galaxy to infer its mass, finding it to be around 12 times the mass of our Sun. He also posted a preprint on arXiv. Congratulations Ed!
The results from the X-ray Imaging and Spectroscopy Mission (XRISM) Cycle 1 review have been published and postdoc Peter Boorman has been awarded an observation of the Compton-thick active galactic nucleus in the nearby galaxy NGC 4945. Congratulations Peter! XRISM is a joint mission between the Japanese Space Agency, JAXA, and NASA, and carries a high-resolution X-ray spectrometer that is one of the coldest instruments ever designed and its spectra are the most detailed ever captured for a wide variety of objects in the universe.
Postdocs Peter Boorman, Ed Nathan and Asia Piotrowska kicked off the summer conference season by travelling to three conferences on three different continents. Peter went to The European Astronomical Society Annual Meeting in Padova, Italy, Asia went to The Latin American Conference on Astrophysics and Relativity in Bogota, Colombia and both Ed and Asia attended COSPAR 2024 in Busan, South Korea.
NuSTAR Science Operations Manager, Karl Forster, was selected to receive NASA’s Exceptional Public Achievement Medal. The award is for a significant specific achievement or substantial improvement in operations, efficiency, service, financial savings, science, or technology which contributes to the mission of NASA. Karl received it for "exceptional achievement in scheduling NuSTAR, enabling it to become a key element of NASA's time-domain and multi-messenger astrophysics program". Congratulations Karl! Very well deserved indeed.
The arrival of summer brings the lastest group of SURF and WAVE fellows to Caltech, here for 10 weeks to undertake summer research. The HEA Group welcomes Sophia Andrews, Indie Desiderio-Sloane, Ollie Jackson, Rahel Joshi, Grace Kallman, Ai-Dan Le, Krystyn Roldan and Paul Shen. Wishing you all a productive and fun time with us!
SPIE is the international society for optics and photonics and held the SPIE Astronomical Telescopes + Instrumentation meeting in Yokohama, Japan. Several members of the UVEX team traveled there to take part, including the UVEX PI Professor Fiona Harrison and Project Scientist Brian Grefenstette. Fiona gave a plenary talk on UVEX where she described the UVEX scientific program and provided an overview of the instrument and mission.
Staff Scientist Hannah Earnshaw traveled to Madrid, Spain to attend the XMM-Newton 2024 Science Workshop on the X-ray mysteries of neutron stars and white dwarfs. They presented their work on ultraluminous X-ray sources in nearby galaxies entitled "The long-term variability of a population of ULXs monitored by Chandra".
Archived HEAG News can be found here!