Explanipedia

Noisy Timing Behavior is a Feature of Central Compact Object Pulsars Open

Karen I. Perez, E. V. Gotthelf, J. P. Halpern · 2025

We present a timing study of the three known central compact object (CCO) pulsars, isolated cooling neutron stars in supernova remnants, using Chandra, XMM-Newton and NICER observations spanning two decades. Relative to canonical young pul…

A Large Systematic Search for Close Supermassive Binary and Rapidly Recoiling Black Holes. IV. Ultraviolet Spectroscopy*† Open

Jessie C. Runnoe, Michael Eracleous, Tamara Bogdanović, J. P. Halpern, Steinn Sigurðsson · 2025

We present Hubble Space Telescope ultraviolet (UV) spectroscopy of 13 quasars at z < 0.7, along with contemporaneous optical spectra from ground-based telescopes. The targets were selected to have broad H β emission lines with substantial …

The Proper Motion of the High Galactic Latitude Pulsar Calvera Open

Michela Rigoselli, S. Mereghetti, J. P. Halpern, E. V. Gotthelf, C. Bassa · 2024

Calvera (1RXS J141256.0+792204) is a pulsar of characteristic age 285 kyr at a high Galactic latitude of b = +37°, detected only in soft thermal X-rays. We measure a new and precise proper motion for Calvera using Chandra High Resolution C…

The Proper Motion of the High Galactic Latitude Pulsar Calvera Open

Michela Rigoselli, S. Mereghetti, J. P. Halpern, E. V. Gotthelf, C. Bassa · 2024

Calvera (1RXS J141256.0+792204) is a pulsar of characteristic age 285 kyr at a high Galactic latitude of b=+37°, detected only in soft thermal X-rays. We measure a new and precise proper motion for Calvera using Chandra HRC-I observations …

X-ray measurement of a high-mass white dwarf and its spin for the intermediate polar IGR J18434−0508 Open

J. Gerber, Jeremy Hare, John A. Tomsick, Benjamin M. Coughenour, A. W. Shaw , et al. · 2024

IGR J18434−0508 is a Galactic Intermediate Polar (IP) type Cataclysmic Variable (CV) previously classified through optical spectroscopy. The source is already known to have a hard Chandra spectrum. In this paper, we have used follow-up XMM…

X-ray measurement of a high-mass white dwarf and its spin for the intermediate polar IGR J18434-0508 Open

J. Gerber, Jeremy Hare, John A. Tomsick, Benjamin M. Coughenour, A. W. Shaw , et al. · 2024

IGR J18434-0508 is a Galactic Intermediate Polar (IP) type Cataclysmic Variable (CV) previously classified through optical spectroscopy. The source is already known to have a hard Chandra spectrum. In this paper, we have used follow-up XMM…

Resolving the Periods of the Asynchronous Polar 1RXS J083842.1–282723 Open

J. P. Halpern · 2024

1RXS J083842.1−282723 is a nearly synchronous magnetic cataclysmic variable with a simple X-ray light curve. While its orbital period was fairly well established at P orb = 98.4 minutes from optical spectroscopy, indirect estimates of P sp…

Resolving the Periods of the Asynchronous Polar 1RXS J083842.1$-$282723 Open

J. P. Halpern · 2024

1RXS J083842.1$-$282723 is a nearly synchronous magnetic cataclysmic variable with a simple X-ray light curve. While its orbital period was fairly well established at $P_{\rm orb}=98.4$ minutes from optical spectroscopy, indirect estimates…

The 2018 X-Ray and Radio Outburst of Magnetar XTE J1810-197 Open

E. V. Gotthelf, J. P. Halpern, Jason Alford, T. Mihara, H. Negoro , et al. · 2024

We present the earliest X-ray observations of the 2018 outburst of XTE. J1810-197, the first outburst since its 2003 discovery as the prototypical transient and radio-emitting anomalous X-ray pulsar (AXP). The Monitor of Allsky X-ray Image…

A Surprising Periodicity Detected during a Super-outburst of V844 Herculis by TESS Open

Anousha Greiveldinger, P. Garnavich, Colin Littlefield, Mark Kennedy, J. P. Halpern , et al. · 2023

We identify a previously undetected periodicity at a frequency of 49.08 ± 0.01 days −1 (period of 29.34 ± 0.01 minutes) during a super-outburst of V844 Her observed by TESS. V844 Her is an SU UMa type cataclysmic variable with an orbital p…

A Surprising Periodicity Detected During a Super-outburst of V844 Herculis by TESS Open

Anousha Greiveldinger, P. Garnavich, Colin Littlefield, Mark Kennedy, J. P. Halpern , et al. · 2023

We identify a previously undetected periodicity at a frequency of 49.08$\pm$0.01 d$^{-1}$ (period of 29.34$\pm$0.01 minutes) during a super-outburst of V844 Her observed by TESS. V844 Her is an SU UMa type cataclysmic variable with an orbi…

Green Bank Telescope Discovery of the Redback Binary Millisecond Pulsar PSR J0212+5321 Open

Karen I. Perez, Slavko Bogdanov, J. P. Halpern, Vishal Gajjar · 2023

We report the discovery of a 2.11 ms binary millisecond pulsar during a targeted search of the redback optical candidate coincident with the γ -ray source 3FGL J0212.5+5320 using the Robert C. Byrd Green Bank Telescope (GBT) with the Break…

Green Bank Telescope Discovery of the Redback Binary Millisecond Pulsar PSR J0212+5321 Open

Karen I. Perez, Slavko Bogdanov, J. P. Halpern, Vishal Gajjar · 2023

We report the discovery of a 2.11 ms binary millisecond pulsar during a targeted search of the redback optical candidate coincident with the $γ$-ray source 3FGL J0212.5+5320 using the Robert C. Byrd Green Bank Telescope (GBT) with the Brea…

Do Central Compact Objects have Carbon Atmospheres? Open

Jason Alford, E. V. Gotthelf, J. P. Halpern · 2023

Only three of the dozen central compact objects (CCOs) in supernova remnants (SNRs) show thermal X-ray pulsations due to non-uniform surface temperature (hot-spots). The absence of X-ray pulsations from several unpulsed CCOs has motivated …

Do Central Compact Objects have Carbon Atmospheres? Open

Jason Alford, J. P. Halpern · 2023

Only three of the dozen central compact objects (CCOs) in supernova remnants (SNRs) show thermal X-ray pulsations due to nonuniform surface temperature (hot spots). The absence of X-ray pulsations from several unpulsed CCOs has motivated s…

Luminous Optical and X-Ray Flaring of the Putative Redback Millisecond Pulsar 1FGL J0523.5–2529 Open

J. P. Halpern, Karen I. Perez, Slavko Bogdanov · 2022

Several redback and black widow millisecond pulsar binaries have episodes of flaring in X-rays and optical. We initially detected such behavior from the Fermi selected redback candidate 1FGL J0523.5–2529 during optical time-series monitori…

Swift J0503.7−2819: a Short-period Asynchronous Polar or Stream-fed Intermediate Polar Open

J. P. Halpern · 2022

We analyze a 7.4 hr XMM-Newton light curve of the cataclysmic variable Swift J0503.7−2819, previously classified using optical periods as an intermediate polar (IP) with an orbital period of 0.0567 days. A photometric signal at 975 s, prev…

Luminous Optical and X-ray Flaring of the Putative Redback Millisecond Pulsar 1FGL J0523.5$-$2529 Open

J. P. Halpern, Karen I. Perez, Slavko Bogdanov · 2022

Several redback and black widow millisecond pulsar binaries have episodes of flaring in X-rays and optical. We initially detected such behavior from the Fermi selected redback candidate 1FGL J0523.5$-$2529 during optical time-series monito…

Optical Light Curve of 4FGL J0935.3+0901: A Flaring Black Widow Candidate Open

J. P. Halpern · 2022

I obtained time-series photometry of the compact binary candidate for the Fermi source 4FGL J0935.3+0901. Superposed on the 2.44 hr orbital modulation are day-to-day variations and frequent flaring as seen in several redback and black wido…

Discovery, Timing, and Multiwavelength Observations of the Black Widow Millisecond Pulsar PSR J1555–2908 Open

Paul S. Ray, L. Nieder, C. J. Clark, S. M. Ransom, H. Thankful Cromartie , et al. · 2022

We report the discovery of PSR J1555−2908, a 1.79 ms radio and gamma-ray pulsar in a 5.6 hr binary system with a minimum companion mass of 0.052 M ⊙ . This fast and energetic ( erg s −1 ) millisecond pulsar was first detected…

Measuring the Nonaxially Symmetric Surface Temperature Distribution of the Central Compact Object in Puppis A Open

Jason Alford, E. V. Gotthelf, Rosalba Perna, J. P. Halpern · 2022

The surface temperature distributions of central compact objects (CCOs) are powerful probes of their crustal magnetic field strengths and geometries. Here we model the surface temperature distribution of RX J0822−4300, the CCO in the Puppi…

Optical data of PSR J1555-2908 Open

Mark Kennedy, R. P. Breton, C. J. Clark, D. Mata Sánchez, Guillaume Voisin , et al. · 2022

The optical data used in the analysis of PSR J1555-2908 presented in Kennedy et al. 2021. The photometry was taken with the ULTRACAM instrument on ESO's New Technology Telescope. The spectroscopy was taken using X-SHOOTER mounted on one of…

Optical data of PSR J1555-2908 Open

Mark Kennedy, R. P. Breton, C. J. Clark, D. Mata Sánchez, Guillaume Voisin , et al. · 2022

The optical data used in the analysis of PSR J1555-2908 presented in Kennedy et al. 2021. The photometry was taken with the ULTRACAM instrument on ESO's New Technology Telescope. The spectroscopy was taken using X-SHOOTER mounted on one of…

Measuring the mass of the black widow PSR J1555-2908 Open

Mark Kennedy, R. P. Breton, C. J. Clark, D. Mata Sánchez, Guillaume Voisin , et al. · 2022

Accurate measurements of the masses of neutron stars are necessary to test binary evolution models, and to constrain the neutron star equation of state. In pulsar binaries with no measurable post-Keplerian parameters, this requires an accu…

Optical Studies of 10 Hard X-Ray-selected Cataclysmic Binaries Open

J. P. Halpern, J. R. Thorstensen · 2022

We conducted time-resolved optical spectroscopy and/or photometry of 10 cataclysmic binaries that were discovered in hard X-ray surveys, with the goal of measuring their orbital periods and searching for evidence that they are magnetic. Fo…

Multiwavelength Observation Campaign of the TeV Gamma-Ray Binary HESS J0632 + 057 with NuSTAR, VERITAS, MDM, and Swift Open

Yarone M. Tokayer, Hongjun An, J. P. Halpern, Jinyoung Kim, Kaya Mori , et al. · 2021

HESS J0632+057 belongs to a rare subclass of binary systems that emit gamma rays above 100 GeV. It stands out for its distinctive high-energy light curve, which features a sharp “primary” peak and broader “secondary” peak. We present the r…

The Rapidly Flaring Afterglow of the Very Bright and Energetic GRB 070125 Open

A. C. Updike, J. B. Haislip, M. Nysewander, A. S. Fruchter, Д. А. Канн , et al. · 2021

We report on multi-wavelength observations, ranging from the X-ray to radio wave bands, of the IPN-localized gamma-ray burst GRB 070125. Spectroscopic observations reveal the presence of absorption lines due to O I, Si II, and C IV, implyi…

The Timing Behavior of the Central Compact Object Pulsar 1E 1207.4−5209 Open

E. V. Gotthelf, J. P. Halpern · 2020

We present 20 yr of timing observations for 1E 1207.4−5209, the central compact object in supernova remnant PKS 1209−51/52, to follow up on our detection of an unexpected timing glitch in its spin-down. Using new XMM-Newton and NICER obser…

The Timing Behavior of the Central Compact Object Pulsar 1E 1207.4-5209 Open

E. V. Gotthelf, J. P. Halpern · 2020

We present 20 years of timing observations for 1E 1207.4-5209, the central compact object in supernova remnant PKS 1209-51/52, to follow up on our detection of an unexpected timing glitch in its spin-down. Using new XMM-Newton and NICER ob…

Multiband Optical Light Curves of Black-widow Pulsars Open

Paul A. Draghis, Roger W. Romani, A. V. Filippenko, Thomas G. Brink, WeiKang Zheng , et al. · 2019

We collect new and archival optical observations of nine “black-widow” millisecond pulsar binaries. New measurements include direct imaging with the Keck, Gemini-S, MDM, and Las Cumbres Observatory 2 m telescopes. This is supplemented by s…

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