Steven R. Ehlert
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View article: Detection of Compton Scattering in the Jet of 3C 84
Detection of Compton Scattering in the Jet of 3C 84 Open
3C 84 is the brightest cluster galaxy in the Perseus Cluster. It is among the closest radio-loud active galaxies and among the very few that can be detected from low-frequency radio up to TeV γ -rays. Here we report on the first X-ray pola…
View article: Detection of Compton Scattering in the Jet of 3C 84
Detection of Compton Scattering in the Jet of 3C 84 Open
3C 84 is the brightest cluster galaxy in the Perseus Cluster. It is among the closest radio-loud active galaxies and among the very few that can be detected from low-frequency radio up to TeV γ -rays. Here we report on the first X-ray pola…
View article: X-Ray Polarization Detection of the Pulsar Wind Nebula in G21.5–0.9 with IXPE
X-Ray Polarization Detection of the Pulsar Wind Nebula in G21.5–0.9 with IXPE Open
We present the X-ray polarization observation of G21.5−0.9, a young Galactic supernova remnant (SNR), conducted with the Imaging X-ray Polarimetry Explorer (IXPE) in 2023 October, with a total livetime of approximately 837 ks. Using differ…
View article: First X-Ray Polarimetric View of a Low-luminosity Active Galactic Nucleus: The Case of NGC 2110
First X-Ray Polarimetric View of a Low-luminosity Active Galactic Nucleus: The Case of NGC 2110 Open
Low-luminosity active galactic nuclei (LLAGN) provide a unique view of Comptonization and nonthermal emission from accreting black holes in the low accretion rate regime. However, to decipher the exact nature of the Comptonizing corona in …
View article: Unveiling blazar synchrotron emission: a multiwavelength polarimetric study of HSP and LSP populations
Unveiling blazar synchrotron emission: a multiwavelength polarimetric study of HSP and LSP populations Open
Polarimetric properties of blazars allow us to put constraints on the acceleration mechanisms that fuel their powerful jets. By studying the multiwavelength polarimetric behaviour of high synchrotron peaked (HSP) and low synchrotron peaked…
View article: NuSTAR Analysis of the 2024 Periastron Passage of TeV Binary PSR B1259-63
NuSTAR Analysis of the 2024 Periastron Passage of TeV Binary PSR B1259-63 Open
PSR B1259-63 is a well-studied TeV binary, with an energetic pulsar in orbit around a Be star. Using Nuclear Spectroscopic Telescope Array observations during the 2024 passage of the pulsar through the circumstellar disk, we find the spect…
View article: IXPE Observations of the Blazar Mrk 501 in 2022: A Multiwavelength View
IXPE Observations of the Blazar Mrk 501 in 2022: A Multiwavelength View Open
The blazar Markarian 501 (Mrk 501) was observed on three occasions over a 4-month period between 2022 March and 2022 July with the Imaging X-ray Polarimetry Explorer (IXPE). In this paper, we report for the first time on the third IXPE obs…
View article: A Two-week IXPE Monitoring Campaign on Mrk 421
A Two-week IXPE Monitoring Campaign on Mrk 421 Open
X-ray polarization is a unique new probe of the particle acceleration in astrophysical jets made possible through the Imaging X-ray Polarimetry Explorer. Here we report on the first dense X-ray polarization monitoring campaign on the blaza…
View article: X-ray Polarization Detection of the Pulsar Wind Nebula in G21.5-0.9 with IXPE
X-ray Polarization Detection of the Pulsar Wind Nebula in G21.5-0.9 with IXPE Open
We present the X-ray polarization observation of G21.5-0.9, a young Galactic supernova remnant (SNR), conducted with the Imaging X-ray Polarimetry Explorer (IXPE) in October 2023, with a total livetime of approximately 837 ks. Using differ…
View article: Determining the origin of the X-ray emission in blazars through multiwavelength polarization
Determining the origin of the X-ray emission in blazars through multiwavelength polarization Open
The origin of the high-energy emission in astrophysical jets from black holes is a highly debated issue. This is particularly true for jets from supermassive black holes, which are among the most powerful particle accelerators in the Unive…
View article: High Optical-to-X-Ray Polarization Ratio Reveals Compton Scattering in BL Lacertae’s Jet
High Optical-to-X-Ray Polarization Ratio Reveals Compton Scattering in BL Lacertae’s Jet Open
Blazars, supermassive black hole systems with highly relativistic jets aligned with the line of sight, are the most powerful long-lived emitters of electromagnetic emission in the Universe. We report here on a radio-to-gamma-ray multiwavel…
View article: X-Ray Polarization of the High-synchrotron-peak BL Lacertae Object 1ES 1959+650 during Intermediate and High X-Ray Flux States
X-Ray Polarization of the High-synchrotron-peak BL Lacertae Object 1ES 1959+650 during Intermediate and High X-Ray Flux States Open
We report the Imaging X-ray Polarimetry Explorer (IXPE) polarimetric and simultaneous multiwavelength observations of the high-energy-peaked BL Lacertae object (HBL) 1ES 1959+650, performed in 2022 October and 2023 August. In 2022 October,…
View article: IXPE observation of the low-synchrotron peaked blazar S4 0954+65 during an optical-X-ray flare
IXPE observation of the low-synchrotron peaked blazar S4 0954+65 during an optical-X-ray flare Open
The X-ray polarization observations, made possible with the Imaging X-ray Polarimetry Explorer (IXPE), offer new ways of probing high-energy emission processes in astrophysical jets from blazars. Here, we report the first X-ray polarizatio…
View article: Evidence for a shock-compressed magnetic field in the northwestern rim of Vela Jr. from X-ray polarimetry
Evidence for a shock-compressed magnetic field in the northwestern rim of Vela Jr. from X-ray polarimetry Open
Synchrotron X-ray emission has been detected from nearly a dozen young supernova remnants (SNRs). X-rays of synchrotron origin exhibit linear polarization in a regular, non-randomly oriented magnetic field. The significant polarized X-ray …
View article: A Two-Week $IXPE$ Monitoring Campaign on Mrk 421
A Two-Week $IXPE$ Monitoring Campaign on Mrk 421 Open
X-ray polarization is a unique new probe of the particle acceleration in astrophysical jets made possible through the Imaging X-ray Polarimetry Explorer. Here we report on the first dense X-ray polarization monitoring campaign on the blaza…
View article: Magnetic Field Geometry of the Gamma-Ray Binary PSR B1259–63 Revealed via X-Ray Polarization
Magnetic Field Geometry of the Gamma-Ray Binary PSR B1259–63 Revealed via X-Ray Polarization Open
Some X-ray binaries containing an energetic pulsar in orbit around a normal star accelerate particles to high energies in the shock cone formed where the pulsar and stellar winds collide. The magnetic field geometry in the acceleration reg…
View article: A Comparison of the X-Ray Polarimetric Properties of Stellar and Supermassive Black Holes
A Comparison of the X-Ray Polarimetric Properties of Stellar and Supermassive Black Holes Open
X-ray polarization provides a new way to probe accretion geometry in black hole systems. If the accretion geometry of black holes is similar regardless of mass, we should expect the same to be true of their polarization properties. We comp…
View article: X-Ray and Multiwavelength Polarization of Mrk 501 from 2022 to 2023
X-Ray and Multiwavelength Polarization of Mrk 501 from 2022 to 2023 Open
We present multiwavelength polarization measurements of the luminous blazar Mrk 501 over a 14 month period. The 2–8 keV X-ray polarization was measured with the Imaging X-ray Polarimetry Explorer (IXPE) with six 100 ks observations spannin…
View article: Analysis of Crab X-Ray Polarization Using Deeper Imaging X-Ray Polarimetry Explorer Observations
Analysis of Crab X-Ray Polarization Using Deeper Imaging X-Ray Polarimetry Explorer Observations Open
We present Crab X-ray polarization measurements using Imaging X-Ray Polarimetry Explorer (IXPE) data with a total exposure of 300 ks, three times more than the initial 2022 discovery paper. Polarization is detected in three times more puls…
View article: Magnetic field geometry of the gamma-ray binary PSR B1259-63 revealed via X-ray polarization
Magnetic field geometry of the gamma-ray binary PSR B1259-63 revealed via X-ray polarization Open
Some X-ray binaries containing an energetic pulsar in orbit around a normal star accelerate particles to high energies in the shock cone formed where the pulsar and stellar winds collide. The magnetic field geometry in the acceleration reg…
View article: Studying geometry of the ultraluminous X-ray pulsar Swift J0243.6+6124 using X-ray and optical polarimetry
Studying geometry of the ultraluminous X-ray pulsar Swift J0243.6+6124 using X-ray and optical polarimetry Open
Discovery of pulsations from a number of ultra-luminous X-ray (ULX) sources proved that accretion onto neutron stars can produce luminosities exceeding the Eddington limit by several orders of magnitude. The conditions necessary to achieve…
View article: A Comparison of the X-ray Polarimetric Properties of Stellar and Supermassive Black Holes
A Comparison of the X-ray Polarimetric Properties of Stellar and Supermassive Black Holes Open
X-ray polarization provides a new way to probe accretion geometry in black hole systems. If the accretion geometry of black holes is similar regardless of mass, we should expect the same to be true of their polarization properties. We comp…
View article: Discovery of a strong rotation of the X-ray polarization angle in the galactic burster GX 13+1
Discovery of a strong rotation of the X-ray polarization angle in the galactic burster GX 13+1 Open
Weakly magnetized neutron stars in X-ray binaries show a complex phenomenology with several spectral components that can be associated with the accretion disk, the boundary, and/or a spreading layer, a corona, and a wind. Spectroscopic inf…
View article: X-ray and multiwavelength polarization of Mrk 501 from 2022 to 2023
X-ray and multiwavelength polarization of Mrk 501 from 2022 to 2023 Open
We present multiwavelength polarization measurements of the luminous blazar Mrk~501 over a 14-month period. The 2--8 keV X-ray polarization was measured with the Imaging X-ray Polarimetry Explorer (IXPE) with six 100-ks observations spanni…
View article: An IXPE-led X-Ray Spectropolarimetric Campaign on the Soft State of Cygnus X-1: X-Ray Polarimetric Evidence for Strong Gravitational Lensing
An IXPE-led X-Ray Spectropolarimetric Campaign on the Soft State of Cygnus X-1: X-Ray Polarimetric Evidence for Strong Gravitational Lensing Open
We present the first X-ray spectropolarimetric results for Cygnus X-1 in its soft state from a campaign of five IXPE observations conducted during 2023 May–June. Companion multiwavelength data during the campaign are likewise shown. The 2–…
View article: IXPE observation of PKS 2155–304 reveals the most highly polarized blazar
IXPE observation of PKS 2155–304 reveals the most highly polarized blazar Open
We report the X-ray polarization properties of the high-synchrotron-peaked (HSP) blazar PKS 2155−304 based on observations with the Imaging X-ray Polarimetry Explorer (IXPE). We observed the source between Oct 27 and Nov 7, 2023. We also c…
View article: Cygnus X-3 revealed as a Galactic ultraluminous X-ray source by IXPE
Cygnus X-3 revealed as a Galactic ultraluminous X-ray source by IXPE Open
View article: Complex rotational dynamics of the neutron star in Hercules X-1 revealed by X-ray polarization
Complex rotational dynamics of the neutron star in Hercules X-1 revealed by X-ray polarization Open
View article: IXPE observation of PKS 2155-304 reveals the most highly polarized blazar
IXPE observation of PKS 2155-304 reveals the most highly polarized blazar Open
We report the X-ray polarization properties of the high-synchrotron-peaked (HSP) blazar PKS 2155$-$304 based on observations with the Imaging X-ray Polarimetry Explorer (IXPE). We observed the source between Oct 27 and Nov 7, 2023. We also…
View article: Tracking the X-Ray Polarization of the Black Hole Transient Swift J1727.8–1613 during a State Transition
Tracking the X-Ray Polarization of the Black Hole Transient Swift J1727.8–1613 during a State Transition Open
We report on an observational campaign on the bright black hole (BH) X-ray binary Swift J1727.8–1613 centered around five observations by the Imaging X-ray Polarimetry Explorer. These observations track for the first time the evolution of …