Stephen Eikenberry’s research interests include black holes, neutron stars, and astronomical instruments including the FLAMINGOS2 near-infrared spectrograph.
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Erupting Black Hole Shows Intriguing "Light Echoes"
Scientific American online
Zeroing in on the corona is especially helpful because scientists think this region is likely the base from which powerful beams of particles and light, called relativistic jets, are launched. These jets travel close to light-speed and can be spotted coming from black holes across the universe. “The big fun of this paper, from my point of view, is that we really can ‘see’ the corona shrinking during the evolution of the outburst,” says Stephen Eikenberry of the University of Florida, a co-author on the new paper. “I don’t know of any real theoretical prediction for this ‘shrinkage’ nor of any prior observation of it, so this result will already require overhauling of the theories we have for jet formation.”
The Astronomer Jocelyn Bell Burnell Looks Back on Her Cosmic Legacy
The New Yorker online
The existence of both neutron stars and black holes was predicted in the nineteen-thirties, and the discovery of pulsars—identified as a type of neutron star soon after CP 1919 was reported—suggested that black holes must be out there, too. The first confirmed black hole was reported a few years later. Pulsars “meant that a lot of this kind of crazy theory that had been kicking around since Einstein dropped the general theory of relativity on us, that maybe it was real,” Stephen Eikenberry, a professor of astronomy at the University of Florida, told me. “Think of it this way: people were asking us to believe in fairies and elves. But then, when you meet an elf, fairies seem like not such a crazy idea.”
Astronomers might need to rethink the way black holes form jets
That poses a challenge for the theories currently used to explain the jets as a result of interactions between the black hole’s magnetic field and matter in its accretion disk — the swirling disk of gas and dust created as matter is trapped by the black hole’s gravity and falls inward. This disk lies outside the event horizon, rendering it visible to astronomers and allowing them to spot the black hole via its light. “Our surprisingly low measurements will force new constraints on theoretical models that previously focused on strong magnetic fields accelerating and directing the jet flows,” said UF professor and study co-author Stephen Eikenberry in a press release. “We weren't expecting this, so it changes much of what we thought we knew."
Black holes' magnetism surprisingly wimpy
The measurements also will help scientists solve the half-century-old mystery of how "jets" of particles traveling at nearly the speed of light shoot out of black holes' magnetic fields, while everything else is sucked into their abysses, said study co-author Stephen Eikenberry, a professor of astronomy in UF's College of Liberal Arts and Sciences.
How strong are black holes really?
UF Innovate online
The measurements also will help scientists solve the half-century-old mystery of how “jets” of particles traveling at nearly the speed of light shoot out of black holes’ magnetic fields, while everything else is sucked into their abysses, said study co-author Stephen Eikenberry, a professor of astronomy in UF’s College of Liberal Arts and Sciences.
Pulsating in Unison at Optical and X-Ray Energies: Simultaneous High Time Resolution Observations of the Transitional Millisecond Pulsar PSR J1023+0038The Astrophysical Journal
PSR J1023+0038 is the first millisecond pulsar discovered to pulsate in the visible band; such a detection took place when the pulsar was surrounded by an accretion disk and also showed X-ray pulsations. We report on the first high time resolution observational campaign of this transitional pulsar in the disk state, using simultaneous observations in the optical (Telescopio Nazionale Galileo, Nordic Optical Telescope, Telescopi Joan Oró), X-ray (XMM-Newton, NuSTAR, NICER), infrared (Gran Telescopio Canarias), and UV (Swift) bands.
Astro2020 Science White Paper: Compact Stellar JetsarXiv preprint arXiv
This paper outlines the importance of understanding jets from compact binaries for the problem of understanding the broader phenomenology of jet production. Because X-ray binaries are nearby and bright, have well-measured system parameters, and vary by factors of ∼106 on ∼ year timescales, they provide a unique opportunity to understand how various aspects of the jet physics change in response to changes in the accretion flow, giving the possibility of looking for trends within individual systems and testing their universality with other systems, rather than trying to interpret large samples of objects on a statistical basis.
Radio frequency timing analysis of the compact jet in the black hole X-ray binary Cygnus X-1Monthly Notices of the Royal Astronomical Society
We present simultaneous multiband radio and X-ray observations of the black hole X-ray binary Cygnus X-1, taken with the Karl G. Jansky Very Large Array and the Nuclear Spectroscopic Telescope Array. With these data, we detect clear flux variability consistent with emission from a variable compact jet. To probe how the variability signal propagates down the jet flow, we perform detailed timing analyses of our data.
Classification and photometric redshift estimation of quasars in photometric surveysProceedings of the International Astronomical Union
We present a machine learning methodology to separate quasars from galaxies and stars using data from S-PLUS in the Stripe-82 region. In terms of quasar classification, we achieved 95.49% for precision and 95.26% for recall using a Random Forest algorithm. For photometric redshift estimation, we obtained a precision of 6% using k-Nearest Neighbour.
The corona contracts in a black-hole transientNature
The geometry of the accretion flow around stellar-mass black holes can change on timescales of days to months1,2,3. When a black hole emerges from quiescence (that is, it ‘turns on’ after accreting material from its companion) it has a very hard (high-energy) X-ray spectrum produced by a hot corona4,5 positioned above its accretion disk, and then transitions to a soft (lower-energy) spectrum dominated by emission from the geometrically thin accretion disk, which extends to the innermost stable circular orbit.
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