About

Deepto Chakrabarty is the William A. M. Burden Professor in Astrophysics and the Department Head of Physics at MIT. His research specialty is in high-energy astrophysics, focusing on the physics and astrophysics of neutron stars. His research interests include observational high-energy astrophysics, such as X-ray and gamma-ray astronomy, optical astronomy, and the study of neutron stars and black holes. Chakrabarty earned his S.B. in Physics from MIT in 1988 and completed his Ph.D. in Physics at Caltech in 1996. Following his doctorate, he worked as a staff physicist at Lawrence Berkeley National Laboratory on the Berkeley Automated Supernova Search and held a postdoctoral fellowship at MIT, including a visiting fellowship at Balliol College, Oxford University. He became an assistant professor at MIT in 1999, was tenured in 2004, and was named Associate Head of the Department in 2020. In 2022, he was appointed as the Head of the Department of Physics. Chakrabarty is a fellow of the American Physical Society and a legacy fellow of the American Astronomical Society. His awards include the 2006 Bruno Rossi Prize in High Energy Astrophysics, an Alfred P. Sloan Research Fellowship, the MIT Buechner Teaching Prize in Physics, and the 2017 MITx Prize for Teaching and Learning in MOOCs. He has chaired the Panel on Compact Objects and Energetic Phenomena of the Astro 2020 Decadal Survey on Astronomy and Astrophysics.

Research topics

• Astrophysics
• Physics
• Astronomy
• Optics

Selected publications

• X-Ray and Radio Campaign of the Z-source GX 340+0. II. The X-Ray Polarization in the Normal Branch

  The Astrophysical Journal · 2026-05-11

  preprintOpen access

  Abstract We present the first X-ray polarization measurement of the neutron star low-mass X-ray binary and Z-source, GX 340+0, in the normal branch (NB) using a 200 ks observation with the Imaging X-ray Polarimetric Explorer (IXPE). This observation was performed in 2024 August. Along with IXPE, we also conducted simultaneous observations with NICER, AstroSat, Insight-HXMT, the Australia Telescope Compact Array (ATCA), and the Giant Metrewave Radio Telescope (GMRT) to investigate the broadband spectral and timing properties in the X-ray and radio wavelengths. During the campaign, the source traced a complete Z-track during the IXPE observation but spent most of the time in the NB. We measure X-ray polarization degree (PD) of 1.3% ± 0.3% in the 2–8 keV energy band with a polarization angle (PA) of 38° ± 6°. The PD in the NB is observed to be weaker than in the horizontal branch (HB) but aligned in the same direction. The PD of the source exhibits a marginal increase with energy, while the PA shows no energy dependence. The joint spectro-polarimetric modeling is consistent with the observed X-ray polarization originating from a single spectral component from the blackbody, the Comptonized emission, or reflection feature, while the disk emission does not contribute toward the X-ray polarization. GMRT observations at 1.26 GHz during HB had a tentative detection at 4.5 ± 0.7 mJy, while ATCA observations a day later during the NB detected the source at 0.70 ± 0.05 mJy and 0.59 ± 0.05 mJy in the 5.5 and 9 GHz bands, respectively, suggesting an evolving jet structure depending on the Z-track position.

  PublisherDOI

• proto-Lightspeed: a high-speed, ultra-low read noise imager on the Magellan Clay Telescope

  ArXiv.org · 2026-01-22

  articleOpen access

  proto-Lightspeed is a new instrument that has been commissioned on the Nasmyth East port of the Magellan Clay Telescope at Las Campanas Observatory to deliver high-speed optical imaging with deep sub-electron read noise. Making use of commercial re-imaging lenses and the ORCA-Quest 2 camera from Hamamatsu, proto-Lightspeed images a field $1'$ in diameter at up to $200$ Hz or windowed fields at higher rates, up to 6600 Hz for a $1.6''\times 1'$ field of view. proto-Lightspeed delivers seeing-limited image quality in the $g'$, $r'$, and $i'$ bands and adjustable magnification for pixel scales between $0.017''-0.050''$. proto-Lightspeed is well suited to studying compact binary systems, exoplanet transits, rapid flaring associated with accretion, periodic optical emission from pulsars, occultations of background stars by small trans-Neptunian Objects, and any other rapidly variable source. proto-Lightspeed will be a P.I. instrument beginning in 2026B, available for use by members of the Magellan Consortium. In this paper, we discuss the design and performance of the instrument, results from its two commissioning runs, and plans for a facility instrument, Lightspeed, to support simultaneous multicolor imaging across a $7'\times4'$ field.

  PublisherOA PDF

• A persistent disk wind and variable jet outflow in the neutron-star low-mass X-ray binary GX 13+1

  ArXiv.org · 2025-04-07

  preprintOpen access

  In low-mass X-ray binaries (LMXBs), accretion flows are often associated with either jet outflows or disk winds. Studies of LMXBs with luminosities up to roughly 20% of the Eddington limit indicate that these outflows generally do not co-occur, suggesting that disk winds might inhibit jets. However, previous observations of LMXBs accreting near or above the Eddington limit show that jets and winds can potentially coexist. To investigate this phenomenon, we carried out a comprehensive multi-wavelength campaign (using VLA, Chandra/HETG, and NICER) on the near-Eddington neutron-star Z source LMXB GX 13+1. NICER and Chandra/HETG observations tracked GX 13+1 across the entire Z-track during high Eddington rates, detecting substantial resonance absorption features originating from the accretion disk wind in all X-ray spectra, which implies a persistent wind presence. Simultaneous VLA observations captured a variable radio jet, with radio emission notably strong during all flaring branch observations-contrary to typical behavior in Z-sources-and weaker when the source was on the normal branch. Interestingly, no clear correlation was found between the radio emission and the wind features. Analysis of VLA radio light curves and simultaneous Chandra/HETG spectra demonstrates that an ionized disk wind and jet outflow can indeed coexist in GX 13+1, suggesting that their launching mechanisms are not necessarily linked in this system.

  PublisherOA PDFDOI

• Parameter constraints for accreting millisecond pulsars with synthetic NICER data

  Monthly Notices of the Royal Astronomical Society · 2025-03-25 · 2 citations

  preprintOpen accessSenior author

  ABSTRACT Pulse profile modelling (PPM) is a technique for inferring mass, radius, and hotspot properties of millisecond pulsars. PPM is now regularly used for the analysis of rotation-powered millisecond pulsars with data from the Neutron Star Interior Composition ExploreR (NICER). Extending PPM to accreting millisecond pulsars (AMPs) is attractive, because they are a different source class featuring bright X-ray radiation from hotspots powered by accretion. In this paper, we present a modification of one of the PPM codes, x-psi, so that it can be used for AMPs. In particular, we implement a model of an accretion disc and atmosphere model appropriate for the hotspots of AMPs, and improve the overall computational efficiency. We then test parameter recovery with simulated NICER data in two scenarios with reasonable parameters for AMPs. We find in the first scenario, where the hotspot is large, that we are able to tightly and accurately constrain all parameters including mass and radius. In the second scenario, which is a high inclination system with a smaller hotspot, we find slightly widened posteriors, degeneracy between a subset of model parameters, and a slight bias in the inferred mass. This analysis of synthetic data lays the ground work for future analysis of AMPs with NICER data. Such an analysis could be complemented by future (joint) analysis of polarization data from the Imaging X-ray Polarimetry Explorer.

  PublisherDOI

• A Gravitational-wave-detectable Candidate Type Ia Supernova Progenitor

  The Astrophysical Journal · 2025-07-09 · 2 citations

  articleOpen access

  Abstract Type Ia supernovae (SNe Ia), critical for studying cosmic expansion, arise from thermonuclear explosions of white dwarfs, but their precise progenitor pathways remain unclear. Growing evidence supports the “double-degenerate scenario,” where two white dwarfs interact. The absence of nondegenerate companions capable of explaining the observed SN Ia rate, along with observations of hypervelocity white dwarfs, interpreted as surviving companions of such systems, provide compelling evidence for this scenario. Upcoming millihertz gravitational-wave observatories like the Laser Interferometer Space Antenna (LISA) are expected to detect thousands of double-degenerate systems, though the most compact known candidate SN Ia progenitors produce marginally detectable signals. Here, we report observations of ATLAS J1138-5139, a binary white dwarf system with an orbital period of just 28 minutes. Our analysis reveals a 1 M ☉ carbon–oxygen white dwarf accreting from a high-entropy helium-core white dwarf. Given its mass, the accreting carbon–oxygen white dwarf is poised to trigger a typical-luminosity SN Ia within a few million years, to evolve into a stably transferring AM Canum Venaticorum (or AM CVn) system, or undergo a merger into a massive white dwarf. ATLAS J1138-5139 provides a rare opportunity to calibrate binary evolution models by directly comparing observed orbital parameters and mass-transfer rates closer to merger than any known SN Ia progenitor. Its compact orbit ensures detectability by LISA, demonstrating the potential of millihertz gravitational-wave observatories to reveal a population of SN Ia progenitors on a Galactic scale, paving the way for multimessenger studies offering insights into the origins of these cosmologically significant explosions.

  PublisherDOI

• Reproduction Package: Parameter Constraints for Accreting Millisecond Pulsars with Synthetic NICER Data

  UvA-DARE (University of Amsterdam) · 2025-03-27

  datasetOpen access

  Reproduction package for the publication "Parameter constraints for accreting millisecond pulsars with synthetic NICER data". Please refer to the readme for detailed information.

  PublisherDOI

• The 2025 outburst of IGR J17511-3057: timing and spectral insights from NICER and NuSTAR

  ePrints Soton (University of Southampton) · 2025-11-01 · 2 citations

  articleOpen access

  Context: IGR J17511−3057 is an accreting millisecond X-ray pulsar and a known type-I burster. The source was observed in outburst for the first time in 2009 and again in 2015, followed by a decade-long quiescence phase. Aims. The source was observed in a new outburst phase starting in February 2025 and lasting at least nine days. We investigated the spectral and temporal properties of IGR J17511−3057, aiming to characterize its current status and highlight possible long-term evolution of its properties. Methods: we analyzed the available NICER and NuSTAR observations performed during the latest outburst of the source. We updated the ephemerides of the neutron star and compared them to previous outbursts to investigate its long-term evolution. We also performed a spectral analysis of the broadband energy spectrum in different outburst phases and investigated the time-resolved spectrum of the type-I X-ray burst event observed with NuSTAR. Results: we detected X-ray pulsations at the frequency of ∼245 Hz. The long-term evolution of the neutron star ephemerides suggests a spin-down derivative of ∼−2.3 × 10 ⁻¹⁵ Hz/s, compatible with a rotation-powered phase while in quiescence. Moreover, the evolution of the orbital period and the time of the ascending node suggests a fast orbital shrinkage, which challenges the standard evolution scenario for this class of pulsars involving angular momentum loss via gravitational wave emission. The spectral analysis revealed a dominant power law-like Comptonization component, along with a thermal blackbody component, consistent with a hard state. Weak broad emission residuals around 6.6 keV suggest the presence of a Kα transition of neutral or He-like Fe originating from the inner region of the accretion disk. A set of self-consistent reflection models confirmed the moderate ionization of the disk truncated at around (82–370) km from the neutron star. Finally, the study of the type-I X-ray burst revealed no signature of photospheric radius expansion. We found marginally significant burst oscillations during the rise and decay of the event, consistent with the neutron star spin frequency.

  PublisherOA PDFDOI

• A Persistent Disk Wind and Variable Jet Outflow in the Neutron-star Low-mass X-Ray Binary GX 13+1

  The Astrophysical Journal · 2025-06-04 · 6 citations

  articleOpen access

  Abstract In low-mass X-ray binaries (LMXBs), accretion flows are often associated with either jet outflows or disk winds. Studies of LMXBs with luminosities up to roughly 20% of the Eddington limit indicate that these outflows generally do not co-occur, suggesting that disk winds might inhibit jets. However, previous observations of LMXBs accreting near or above the Eddington limit show that jets and winds can potentially coexist. To investigate this phenomenon, we carried out a comprehensive multiwavelength campaign (using the Very Large Array (VLA), Chandra/High Energy Transmission Grating Spectrometer (HETG), and NICER) on the near-Eddington neutron-star Z-source LMXB GX 13+1. NICER and Chandra/HETG observations tracked GX 13+1 across the entire Z track during high Eddington rates, detecting substantial resonance absorption features originating from the accretion disk wind in all X-ray spectra, which implies a persistent wind presence. Simultaneous VLA observations captured a variable radio jet, with radio emission notably strong during all flaring branch observations—contrary to typical behavior in Z sources—and weaker when the source was on the normal branch. Interestingly, no clear correlation was found between the radio emission and the wind features. Analysis of VLA radio light curves and simultaneous Chandra/HETG spectra demonstrates that an ionized disk wind and jet outflow can indeed coexist in GX 13+1, suggesting that their launching mechanisms are not necessarily linked in this system.

  PublisherDOI

• The black hole low-mass X-ray binary V404 Cygni is part of a wide triple

  Nature · 2024-10-23 · 24 citations

  article
  PublisherDOI

• A gravitational wave detectable candidate Type Ia supernova progenitor

  White Rose Research Online (University of Leeds, The University of Sheffield, University of York) · 2024-11-29

  preprintOpen access

  Type Ia supernovae, critical for studying cosmic expansion, arise from thermonuclear explosions of white dwarfs, but their precise progenitor pathways remain unclear. Growing evidence supports the ``double-degenerate'' scenario, where two white dwarfs interact. The absence of other companion types capable of explaining the observed Ia rate, along with observations of hyper-velocity white dwarfs interpreted as surviving companions of such systems provide compelling evidence in favor of this scenario. Upcoming millihertz gravitational wave observatories like the Laser Interferometer Space Antenna (LISA) are expected to detect thousands of double-degenerate systems, though the most compact known candidate Ia progenitors produce only marginally detectable gravitational wave signals. Here, we report observations of ATLAS J1138-5139, a binary white dwarf system with an orbital period of 28 minutes. Our analysis reveals a 1 solar mass carbon-oxygen white dwarf accreting from a helium-core white dwarf. Given its mass, the accreting carbon-oxygen white dwarf is poised to trigger a typical-luminosity Type Ia supernova within a few million years, or to evolve into a stably mass-transferring AM CVn system. ATLAS J1138-5139 provides a rare opportunity to calibrate binary evolution models by directly comparing observed orbital parameters and mass transfer rates closer to merger than any previously identified candidate Type Ia progenitor. Its compact orbit ensures detectability by LISA, demonstrating the potential of millihertz gravitational wave observatories to reveal a population of Type Ia progenitors on a Galactic scale, paving the way for multi-messenger studies offering insights into the origins of these cosmologically significant explosions.

  PublisherOA PDFDOI

Frequent coauthors

• Sebastien Guillot

  Institut de Recherche en Astrophysique et Planétologie

  202 shared

• Tod E. Strohmayer

  Goddard Space Flight Center

  148 shared

• Paul S. Ray

  United States Naval Research Laboratory

  123 shared

• Keith C. Gendreau

  113 shared

• Zaven Arzoumanian

  108 shared

• C. B. Markwardt

  89 shared

• Anna L. Watts

  The Netherlands Cancer Institute

  89 shared

• D. K. Galloway

  Monash University

  80 shared

Education

• PhD, Physics

  California Institute of Technology

  1996

• SB, Physics

  Massachusetts Institute of Technology

  1988

Awards & honors

• American Astronomical Society Legacy Fellow (2020)
• MITx Prize for Teaching and Learning in MOOCs (2017)
• Bruno Rossi Prize in High Energy Astrophysics (2006)
• Sloan Research Fellowship (2001)
• Buechner Teaching Prize in Physics (MIT) (2001)