An X-ray image of the Tycho supernova remnant built up from years of
observations by the Chandra space telescope, showing the clumpy shape of
the explosion's debris. New NuSTAR data will locate energetic sites of
cosmic ray acceleration within the remnant.
Image credit: NASA/CXC/RIKEN & GSFC/T. Sato et al; DSS. Download Image
NuSTAR recently observed the distant gamma-ray blazar 4FGL
J1428.9+5406 in response to a flare detected by NASA’s Fermi-LAT
gamma-ray telescope. Blazars are a subclass of active galaxies—that is,
galaxies containing a central supermassive black hole that is actively
consuming matter—capable of launching relativistic jets aligned with our
line of sight. These objects are highly variable and can produce bright
flares lasting from a few days to several weeks. In the early Universe,
blazars are typically faint gamma-ray sources and are only detectable
during such flare events. These rare flares offer valuable insights into
the physics of black hole jets at redshifts greater than 3—that is,
within the first 2 billion years after the Big Bang. This NuSTAR
observation of 4FGL J1428.9+5406 was triggered by a team monitoring
about 80 high-redshift blazars with Fermi-LAT. Their program aims to
collect near-simultaneous data across multiple wavelengths, from radio
to X-ray, which are essential for probing the origin of the flare and
constraining the power of the jet. Understanding how such powerful jets
are launched and sustained in the early Universe will inform models of
black hole growth and feedback during this epoch of high activity.
Last week, NuSTAR observed the Tycho supernova remnant, the remains of a stellar explosion that was famously visible to the naked eye 453 years ago. Young supernova remnants like Tycho are known to accelerate cosmic rays, such as electrons, to ultra-relativistic energies exceeding 1 TeV. This extreme phenomenon can be detected in the high energy X-ray band through synchrotron radiation emitted by these energetic electrons. NuSTAR first observed the Tycho remnant in 2014 for a total of 750 ks—more than eight days of exposure time—showcasing its exceptional high energy X-ray imaging and spectral capabilities by pinpointing the most energetic acceleration sites down to arcminute scales within this 9-arcminute-wide remnant, and precisely measuring their synchrotron spectra to high X-ray energies of 40 keV. A new observation begun last week totaling 500 ks, or nearly six days, will reveal how Tycho's electron acceleration has evolved over the past decade, providing a unique opportunity to tightly constrain the spectrum of accelerated electrons, deepen our understanding of cosmic-ray acceleration mechanisms, and estimate Tycho's contribution to the most energetic Galactic cosmic rays. For a related study by the same team of researchers on a similar source, see this recent article about Cassiopeia A.
Authors: Andrea Gokus (McDonnell Center Postdoctoral Fellow, Washington University), Jooyun Woo (Postdoctoral scholar, Columbia University), Hannah Earnshaw (NuSTAR Project Scientist, Caltech).
Last week, NuSTAR observed the Tycho supernova remnant, the remains of a stellar explosion that was famously visible to the naked eye 453 years ago. Young supernova remnants like Tycho are known to accelerate cosmic rays, such as electrons, to ultra-relativistic energies exceeding 1 TeV. This extreme phenomenon can be detected in the high energy X-ray band through synchrotron radiation emitted by these energetic electrons. NuSTAR first observed the Tycho remnant in 2014 for a total of 750 ks—more than eight days of exposure time—showcasing its exceptional high energy X-ray imaging and spectral capabilities by pinpointing the most energetic acceleration sites down to arcminute scales within this 9-arcminute-wide remnant, and precisely measuring their synchrotron spectra to high X-ray energies of 40 keV. A new observation begun last week totaling 500 ks, or nearly six days, will reveal how Tycho's electron acceleration has evolved over the past decade, providing a unique opportunity to tightly constrain the spectrum of accelerated electrons, deepen our understanding of cosmic-ray acceleration mechanisms, and estimate Tycho's contribution to the most energetic Galactic cosmic rays. For a related study by the same team of researchers on a similar source, see this recent article about Cassiopeia A.
Authors: Andrea Gokus (McDonnell Center Postdoctoral Fellow, Washington University), Jooyun Woo (Postdoctoral scholar, Columbia University), Hannah Earnshaw (NuSTAR Project Scientist, Caltech).
