33 results on '"Laura Shishkovsky"'
Search Results
2. The MAVERIC survey: a catalogue of radio sources in southern globular clusters from the Australia Telescope Compact Array
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Vlad Tudor, James C A Miller-Jones, Jay Strader, Arash Bahramian, Laura Shishkovsky, Richard M Plotkin, Laura Chomiuk, Craig O Heinke, Thomas J Maccarone, Gregory R Sivakoff, Evangelia Tremou, Gemma E Anderson, Thomas D Russell, and Anastasios K Tzioumis
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High Energy Astrophysical Phenomena (astro-ph.HE) ,Space and Planetary Science ,Astrophysics::High Energy Astrophysical Phenomena ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics::Galaxy Astrophysics - Abstract
Radio continuum observations offer a new window on compact objects in globular clusters compared to typical X-ray or optical studies. As part of the MAVERIC survey, we have used the Australia Telescope Compact Array to carry out a deep (median central noise level of approximately 4 microJy per beam) radio continuum survey of 26 southern globular clusters at central frequencies of 5.5 and 9.0 GHz. This paper presents a catalogue of 1285 radio continuum sources in the fields of these 26 clusters. Considering the surface density of background sources, we find significant evidence for a population of radio sources in seven of the 26 clusters, and also identify at least 11 previously known compact objects (6 pulsars and 5 X-ray binaries). While the overall density of radio continuum sources with 7.25-GHz flux densities greater than about 20 microJy in typical globular clusters is relatively low, the survey has already led to the discovery of several exciting compact binaries, including a candidate ultracompact black hole X-ray binary in 47 Tuc. Many of the unclassified radio sources near the centres of the clusters are likely to be true cluster sources, and multi-wavelength follow-up will be necessary to classify these objects and better understand the demographics of accreting compact binaries in globular clusters., 16 pages, 7 figures, accepted for publication in MNRAS
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- 2022
3. The MAVERIC Survey: Simultaneous Chandra and VLA observations of the transitional millisecond pulsar candidate NGC 6652B
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Evangelia Tremou, Richard M. Plotkin, Adela Kawka, Gregory R. Sivakoff, Aarran W. Shaw, Vlad Tudor, Christopher Britt, Thomas J. Maccarone, Laura Chomiuk, James Miller-Jones, Laura Shishkovsky, Arash Bahramian, Alessandro Paduano, Craig O. Heinke, Jay Strader, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
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Astrophysics::High Energy Astrophysical Phenomena ,FOS: Physical sciences ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,01 natural sciences ,Jansky ,stars: neutron ,X-rays: binaries ,accretion ,Observatory ,Millisecond pulsar ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,Absorption (logic) ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,High Energy Astrophysical Phenomena (astro-ph.HE) ,Physics ,Accretion (meteorology) ,010308 nuclear & particles physics ,Astronomy and Astrophysics ,accretion discs ,Neutron star ,Photometry (astronomy) ,Space and Planetary Science ,Globular cluster ,globular clusters: individual: NGC 6652 ,Astrophysics - High Energy Astrophysical Phenomena ,[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] - Abstract
Transitional millisecond pulsars are millisecond pulsars that switch between a rotation-powered millisecond pulsar state and an accretion-powered X-ray binary state, and are thought to be an evolutionary stage between neutron star low-mass X-ray binaries and millisecond pulsars. So far, only three confirmed systems have been identified in addition to a handful of candidates. We present the results of a multi-wavelength study of the low-mass X-ray binary NGC 6652B in the globular cluster NGC 6652, including simultaneous radio and X-ray observations taken by the Karl G. Jansky Very Large Array and the Chandra X-ray Observatory, and optical spectroscopy and photometry. This source is the second brightest X-ray source in NGC 6652 ($L_{\textrm{X}}\sim1.8\times10^{34}$ erg s$^{-1}$) and is known to be variable. We observe several X-ray flares over the duration of our X-ray observations, in addition to persistent radio emission and occasional radio flares. Simultaneous radio and X-ray data show no clear evidence of anti-correlated variability. Optical spectra of NGC 6652B indicate variable, broad H $\alpha$ emission which transitions from double-peaked emission to absorption over a time-scale of hours. We consider a variety of possible explanations for the source behaviour, and conclude that based on the radio and X-ray luminosities, short time-scale variability and X-ray flaring, and optical spectra, NGC 6652B is best explained as a transitional millisecond pulsar candidate that displays prolonged X-ray flaring behaviour. However, this could only be confirmed with observations of a change to the rotation-powered millisecond pulsar state., Comment: 15 pages, 8 figures, accepted for publication in MNRAS
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- 2021
4. The MAVERIC Survey: Radio Catalogs and Source Counts from Deep Very Large Array Imaging of 25 Galactic Globular Clusters
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Laura Shishkovsky, Jay Strader, Laura Chomiuk, Evangelia Tremou, Vlad Tudor, James C. A. Miller-Jones, Arash Bahramian, Craig O. Heinke, Thomas J. Maccarone, and Gregory R. Sivakoff
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- 2020
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5. PSR J1306-40: An X-Ray Luminous Redback with an Evolved Companion
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Samuel J. Swihart, Jay Strader, Laura Chomiuk, and Laura Shishkovsky
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- 2019
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6. The MAVERIC Survey: Variable Jet-Accretion Coupling in Luminous Accreting Neutron Stars in Galactic Globular Clusters
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Teresa Panurach, Jay Strader, Arash Bahramian, Laura Chomiuk, James C. A. Miller-Jones, Craig O. Heinke, Thomas J. Maccarone, Laura Shishkovsky, Gregory R. Sivakoff, Evangelia Tremou, Vlad Tudor, Ryan Urquhart, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
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High Energy Astrophysical Phenomena (astro-ph.HE) ,010308 nuclear & particles physics ,Astrophysics::High Energy Astrophysical Phenomena ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,Space and Planetary Science ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] ,Astrophysics - High Energy Astrophysical Phenomena ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics - Abstract
Accreting neutron stars in low-mass X-ray binaries show outflows -- and sometimes jets -- in the general manner of accreting black holes. However, the quantitative link between the accretion flow (traced by X-rays) and outflows and/or jets (traced by radio emission) is much less well-understood for neutron stars than for black holes, other than the general observation that neutron stars are fainter in the radio at a given X-ray luminosity. We use data from the deep MAVERIC radio continuum survey of Galactic globular clusters for a systematic radio and X-ray study of six luminous (L_X > 10^34 erg/s) persistent neutron star X-ray binaries in our survey, as well as two other transient systems also captured by our data. We find that these neutron star X-ray binaries show an even larger range in radio luminosity than previously observed. In particular, in quiescence at L_X ~ 3x10^34 erg/s, the confirmed neutron star binary GRS 1747--312 in Terzan 6 sits near the upper envelope of the black hole radio/X-ray correlation, and the persistently accreting neutron star systems AC 211 (in M15) and X1850--087 (in NGC 6712) show unusual radio variability and luminous radio emission. We interpret AC 211 as an obscured "Z source" that is accreting at close to the Eddington limit, while the properties of X1850--087 are difficult to explain, and motivate future coordinated radio and X-ray observations. Overall, our results show that neutron stars do not follow a single relation between inflow and outflow, and confirm that their accretion dynamics are more complex than for black holes., 27 pages, 9 figures, 4 tables, accepted for publication in ApJ
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- 2021
7. The loudest stellar heartbeat: characterizing the most extreme amplitude heartbeat star system
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Benjamin J. Shappee, Andrea K. Dupree, Katie Auchettl, Kristen C. Dage, Tharindu Jayasinghe, Ian B. Thompson, Laura Chomiuk, Elias Aydi, Karina T. Voggel, Kirill Sokolovsky, Laura Shishkovsky, Samuel J. Swihart, Jason T. Hinkle, Christopher S. Kochanek, Jay Strader, K. Z. Stanek, Todd A. Thompson, Patrick J. Vallely, A Hughes, Observatoire astronomique de Strasbourg (ObAS), and Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
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Physics ,Heartbeat ,010308 nuclear & particles physics ,FOS: Physical sciences ,Balmer series ,Astronomy and Astrophysics ,Astrophysics ,Stellar classification ,01 natural sciences ,Exoplanet ,symbols.namesake ,Supernova ,Stars ,Astrophysics - Solar and Stellar Astrophysics ,13. Climate action ,Space and Planetary Science ,[SDU]Sciences of the Universe [physics] ,0103 physical sciences ,symbols ,Supergiant ,Large Magellanic Cloud ,010303 astronomy & astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) - Abstract
We characterize the extreme heartbeat star system MACHO 80.7443.1718 in the LMC using TESS photometry and spectroscopic observations from the Magellan Inamori Kyocera Echelle (MIKE) and SOAR Goodman spectographs. MACHO 80.7443.1718 was first identified as a heartbeat star system in the All-Sky Automated Survey for SuperNovae (ASAS-SN) with $P_{\rm orb}=32.836\pm0.008\,{\rm d}$. MACHO 80.7443.1718 is a young (${\sim}6$~Myr), massive binary, composed of a B0 Iae supergiant with $M_1 \simeq 35 M_\odot$ and an O9.5V secondary with $M_2 \simeq 16 M_\odot$ on an eccentric ($e=0.51\pm0.03$) orbit. In addition to having the largest variability amplitude amongst all known heartbeats stars, MACHO 80.7443.1718 is also one of the most massive heartbeat stars yet discovered. The B[e] supergiant has Balmer emission lines and permitted/forbidden metallic emission lines associated with a circumstellar disk. The disk rapidly dissipates at periastron which could indicate mass transfer to the secondary, but re-emerges immediately following periastron passage. MACHO 80.7443.1718 also shows tidally excited oscillations at the $N=25$ and $N=41$ orbital harmonics and has a rotational period of 4.4 d., 21 pages, 16 figures. Submitted to MNRAS
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- 2021
8. Discovery of a New Redback Millisecond Pulsar Candidate: 4FGL J0940.3-7610
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Elias Aydi, Laura Chomiuk, Jay Strader, Laura Shishkovsky, Samuel J. Swihart, and Kristen C. Dage
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010504 meteorology & atmospheric sciences ,Astrophysics::High Energy Astrophysical Phenomena ,X-ray binary ,FOS: Physical sciences ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,law.invention ,Telescope ,Millisecond pulsar ,law ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,0105 earth and related environmental sciences ,Physics ,Orbital elements ,High Energy Astrophysical Phenomena (astro-ph.HE) ,Center (category theory) ,Astronomy and Astrophysics ,Light curve ,Orbit ,Neutron star ,Space and Planetary Science ,Astrophysics::Earth and Planetary Astrophysics ,Astrophysics - High Energy Astrophysical Phenomena - Abstract
We have discovered a new candidate redback millisecond pulsar binary near the center of the error ellipse of the bright unassociated Fermi-LAT $\gamma$-ray source 4FGL J0940.3-7610. The candidate counterpart is a variable optical source that also shows faint X-ray emission. Optical photometric and spectroscopic monitoring with the SOAR telescope indicates the companion is a low-mass star in a 6.5-hr orbit around an invisible primary, showing both ellipsoidal variations and irradiation and consistent with the properties of known redback millisecond pulsar binaries. Given the orbital parameters, preliminary modeling of the optical light curves suggests an edge-on inclination and a low-mass ($\sim 1.2$ - $1.4\,M_{\odot}$) neutron star, along with a secondary mass somewhat more massive than typical $\gtrsim 0.4\,M_{\odot}$. This combination of inclination and secondary properties could make radio eclipses more likely for this system, explaining its previous non-discovery in radio pulsation searches. Hence 4FGL J0940.3-7610 may be a strong candidate for a focused search for $\gamma$-ray pulsations to enable the future detection of a millisecond pulsar., Comment: 8 pages, 3 figures, 1 table; Accepted to ApJ
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- 2021
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9. The MAVERIC Survey: Dynamical Origin of Radio Sources in Galactic Globular Clusters
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Arash Bahramian, Craig O. Heinke, Yue Zhao, Gregory R. Sivakoff, Laura Shishkovsky, Thomas J. Maccarone, Laura Chomiuk, James Miller-Jones, Evangelia Tremou, Jay Strader, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
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High Energy Astrophysical Phenomena (astro-ph.HE) ,Physics ,010504 meteorology & atmospheric sciences ,Astrophysics::High Energy Astrophysical Phenomena ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Radius ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,Luminosity ,Black hole ,Neutron star ,Space and Planetary Science ,Millisecond pulsar ,Stellar dynamics ,Globular cluster ,0103 physical sciences ,Source counts ,Astrophysics - High Energy Astrophysical Phenomena ,[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,0105 earth and related environmental sciences - Abstract
We investigate potential correlations between radio source counts (after background corrections) of 22 Galactic globular clusters (GCs) from the MAVERIC survey, and stellar encounter rates ($\Gamma$) and masses ($M$) of the GCs. Applying a radio luminosity limit of $L_\mathrm{lim}=5.0\times 10^{27}~\mathrm{erg~s^{-1}}$, we take a census of radio sources in the core and those within the half-light radius. By following a maximum likelihood method and adopting a simplified linear model, we find an unambiguous dependence of core radio source counts on $\Gamma$ and/or $M$ at 90% confidence, but no clear dependence of source counts within the half-light radius on either $\Gamma$ or $M$. Five of the identified radio sources in cores above our adopted limit are millisecond pulsars or neutron star X-ray binaries (XRBs), the dependence of which on $\Gamma$ is well-known, but another is a published black hole (BH) XRB candidate, and ten others are not identified. Accounting for the verified cluster members increases the significance of correlation with $M$ and/or $\Gamma$ (to 99% confidence), for fits to core and half-light region source counts, while excluding a dependence on $\Gamma$ alone at 90% (core) and 68% (half-light) confidence. This is consistent with published dynamical simulations of GC BH interactions that argue $\Gamma$ will be a poor predictor of the distribution of accreting BHs in GCs. Future multiwavelength follow-up to verify cluster membership will enable stronger constraints on the dependence of radio source classes on cluster properties, promising a new view on the dynamics of BHs in GCs., Comment: 12 pages, 4 figures, accepted for publication in ApJ
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- 2021
10. The MAVERIC Survey: New compact binaries revealed by deep radio continuum observations of the Galactic globular cluster Terzan 5
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James Miller-Jones, Samuel J. Swihart, Yuankun Wang, Jay Strader, Ryan Urquhart, Vlad Tudor, Evangelia Tremou, Gregory R. Sivakoff, Scott M. Ransom, Arash Bahramian, Laura Shishkovsky, Craig O. Heinke, Thomas J. Maccarone, Laura Chomiuk, Alexandra J. Tetarenko, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)
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010504 meteorology & atmospheric sciences ,Astrophysics::High Energy Astrophysical Phenomena ,Population ,Continuum (design consultancy) ,FOS: Physical sciences ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,Radio spectrum ,Jansky ,Pulsar ,Millisecond pulsar ,0103 physical sciences ,education ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,0105 earth and related environmental sciences ,Physics ,High Energy Astrophysical Phenomena (astro-ph.HE) ,education.field_of_study ,Astrophysics::Instrumentation and Methods for Astrophysics ,Astronomy and Astrophysics ,Light curve ,Space and Planetary Science ,Globular cluster ,[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] ,Astrophysics - High Energy Astrophysical Phenomena - Abstract
Owing to its massive, dense core, Terzan 5 has the richest population of millisecond pulsars known among Galactic globular clusters. Here we report new deep $2-8\,$GHz radio continuum observations of Terzan\,5 obtained with the Karl G. Jansky Very Large Array. We have identified a total of 24 sources within the cluster half-light radius, including 17 within the core radius. 19 are associated with previously studied millisecond pulsars and X-ray binaries. Three of the new radio sources have steep radio spectra and are located within the cluster core, as expected for millisecond pulsars. These three sources have hard X-ray photon indices ($\Gamma=1.3-1.5$) and highly variable X-ray emission, suggesting they are binary millisecond pulsars belonging to the spider class. For the most X-ray luminous of these sources, the redback spider classification is confirmed by its X-ray light curve, which shows an orbital period of 12.32 hr and double peaked structure around X-ray maximum. The likely discovery of bright binary millisecond pulsars in a well-studied cluster like Terzan 5 highlights how deep radio continuum imaging can complement pulsar search and timing observations in finding probable eclipsing systems. The other new radio source in the core has a flat radio spectrum and is X-ray faint ($L_X \approx 2\times 10^{31}$ erg s$^{-1}$) with a photon index $\Gamma=2.1\pm0.5$, consistent with the properties expected for a quiescent stellar-mass black hole X-ray binary., Comment: 19 pages, 12 figures, 3 tables. Accepted for publication in ApJ
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- 2020
11. A deep Chandra survey for faint X-ray sources in the Galactic globular cluster M30, and searches for optical and radio counterparts
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James Miller-Jones, Yue Zhao, Thomas J. Maccarone, Laura Chomiuk, Phyllis M. Lugger, Arash Bahramian, Constanza Echiburú, Evangelia Tremou, Haldan N. Cohn, Jay Strader, Laura Shishkovsky, Craig O. Heinke, Gregory R. Sivakoff, Sebastien Guillot, Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Centre National d'Études Spatiales [Toulouse] (CNES), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)
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Physics ,High Energy Astrophysical Phenomena (astro-ph.HE) ,Active galactic nucleus ,010308 nuclear & particles physics ,galaxies: star clusters: individual: M30 ,X-ray ,Binary number ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Radius ,Type (model theory) ,01 natural sciences ,Jansky ,X-rays: binaries ,Space and Planetary Science ,Millisecond pulsar ,Globular cluster ,0103 physical sciences ,Astrophysics - High Energy Astrophysical Phenomena ,[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] ,010303 astronomy & astrophysics - Abstract
We present a deep ($\sim 330~\mathrm{ks}$) {\it Chandra} survey of the Galactic globular cluster M30 (NGC 7099). Combining the new Cycle 18 with the previous Cycle 3 observations we report a total of 10 new X-ray point sources within the $1.03$ arcmin half-light radius, compiling an extended X-ray catalogue of a total of 23 sources. We incorporate imaging observations by the {\it Hubble Space Telescope} and the {\it Karl G. Jansky Very Large Array} from the MAVERIC survey to search for optical and radio counterparts to the new and old sources. Two X-ray sources are found to have a radio counterpart, including the known millisecond pulsar PSR J2140$-$2310A, the radio position of which also matches a previously reported faint optical counterpart which is slightly redder than the main sequence. We found optical counterparts to $18$ of the $23$ X-ray sources, identifying $2$ new cataclysmic variables (CVs), $5$ new CV candidates, $2$ new candidates of RS CVn type of active binary (AB), and $2$ new candidates of BY Dra type of AB. The remaining unclassified X-ray sources are likely background active galactic nuclei (AGN), as their number is consistent with the expected number of AGN at our X-ray sensitivity. Finally, our analysis of radial profiles of different source classes suggests that bright CVs are more centrally distributed than faint CVs in M30, consistent with other core-collapsed globular clusters., Comment: 24 pages, 12 figures, accepted for publication in Monthly Notices of the Royal Astronomical Society
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- 2020
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12. Early spectral evolution of classical novae: consistent evidence for multiple distinct outflows
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E. Steinberg, J. Leahy-McGregor, E. J. Harvey, Marina Orio, Koji Mukai, Luca Izzo, David A. H. Buckley, A. Kawash, Patrick A. Woudt, Elias Aydi, F. M. Walter, Christopher S. Kochanek, J. L. Sokoloski, Brian D. Metzger, Laura Shishkovsky, Benjamin J. Shappee, Jay Strader, J. D. Linford, Samuel J. Swihart, Laura Chomiuk, and Kirill Sokolovsky
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Physics ,High Energy Astrophysical Phenomena (astro-ph.HE) ,010504 meteorology & atmospheric sciences ,Astrophysics::High Energy Astrophysical Phenomena ,Cataclysmic variable star ,White dwarf ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,01 natural sciences ,Common envelope ,Stars ,13. Climate action ,Space and Planetary Science ,0103 physical sciences ,Binary star ,Astrophysics::Solar and Stellar Astrophysics ,Variable star ,Circumbinary planet ,Ejecta ,Astrophysics - High Energy Astrophysical Phenomena ,010303 astronomy & astrophysics ,0105 earth and related environmental sciences - Abstract
The physical mechanism driving mass ejection during a nova eruption is still poorly understood. Possibilities include ejection in a single ballistic event, a common envelope interaction, a continuous wind, or some combination of these processes. Here we present a study of 12 Galactic novae, for which we have pre-maximum high-resolution spectroscopy. All 12 novae show the same spectral evolution. Before optical peak, they show a slow P Cygni component. After peak a fast component quickly arises, while the slow absorption remains superimposed on top of it, implying the presence of at least two physically distinct flows. For novae with high-cadence monitoring, a third, intermediate-velocity component is also observed. These observations are consistent with a scenario where the slow component is associated with the initial ejection of the accreted material and the fast component with a radiation-driven wind from the white dwarf. When these flows interact, the slow flow is swept up by the fast flow, producing the intermediate component. These colliding flows may produce the gamma-ray emission observed in some novae. Our spectra also show that the transient heavy element absorption lines seen in some novae have the same velocity structure and evolution as the other lines in the spectrum, implying an association with the nova ejecta rather than a pre-existing circumbinary reservoir of gas or material ablated from the secondary. While this basic scenario appears to qualitatively reproduce multi-wavelength observations of classical novae, substantial theoretical and observational work is still needed to untangle the rich diversity of nova properties., Comment: 39 pages, 35 figures, submitted to ApJ
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- 2020
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13. The MAVERIC survey: A hidden pulsar and a black hole candidate in ATCA radio imaging of the globular cluster NGC 6397
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Gregory R. Sivakoff, Manuel Pichardo Marcano, Arash Bahramian, James Miller-Jones, Yue Zhao, Thomas J. Maccarone, Laura Chomiuk, Vlad Tudor, Jay Strader, Joseph D. Gelfand, Laura Shishkovsky, and Craig O. Heinke
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Physics ,High Energy Astrophysical Phenomena (astro-ph.HE) ,010308 nuclear & particles physics ,Astrophysics::High Energy Astrophysical Phenomena ,FOS: Physical sciences ,Astronomy and Astrophysics ,Radius ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,Galaxy ,law.invention ,Telescope ,Black hole ,Pulsar ,Space and Planetary Science ,Millisecond pulsar ,law ,Globular cluster ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics - High Energy Astrophysical Phenomena ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,Eclipse - Abstract
Using a 16.2 hr radio observation by the Australia Telescope Compact Array (ATCA) and archival Chandra data, we found $>5\sigma$ radio counterparts to 4 known and 3 new X-ray sources within the half-light radius ($r_\mathrm{h}$) of the Galactic globular cluster NGC 6397. The previously suggested millisecond pulsar (MSP) candidate, U18, is a steep-spectrum ($S_\nu \propto \nu^\alpha$; $\alpha=-2.0^{+0.4}_{-0.5}$) radio source with a 5.5 GHz flux density of $54.7\pm 4.3~\mathrm{\mu Jy}$. We argue that U18 is most likely a "hidden" MSP that is continuously hidden by plasma shocked at the collision between the winds from the pulsar and companion star. The nondetection of radio pulsations so far is probably the result of enhanced scattering in this shocked wind. On the other hand, we observed 5.5 GHz flux of the known MSP PSR J1740-5340 (U12) to decrease by a factor of $>2.8$ during epochs of 1.4 GHz eclipse, indicating that the radio flux is absorbed in its shocked wind. If U18 is indeed a pulsar whose pulsations are scattered, we note the contrast with U12's flux decrease in eclipse, which argues for two different eclipse mechanisms at the same radio frequency. In addition to U12 and U18, we also found radio associations for 5 other Chandra X-ray sources, four of which are likely background galaxies. The last, U97, which shows strong H$\alpha$ variability, is mysterious; it may be either a quiescent black hole low-mass X-ray binary, or something more unusual., Comment: Accepted for publication in Monthly Notices of the Royal Astronomical Society. 18 pages, 9 figures, 4 tables
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- 2020
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14. The MAVERIC Survey: Chandra/ACIS Catalog of Faint X-ray sources in 38 Galactic globular clusters
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Arash Bahramian, James Miller-Jones, Craig O. Heinke, Jay Strader, Gregory R. Sivakoff, Vlad Tudor, Evangelia Tremou, Yue Zhao, K. L. Li, David Pooley, Thomas J. Maccarone, Laura Chomiuk, Johannes Buchner, Laura Shishkovsky, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)
- Subjects
010504 meteorology & atmospheric sciences ,Astrophysics::High Energy Astrophysical Phenomena ,FOS: Physical sciences ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,Millisecond pulsar ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,0105 earth and related environmental sciences ,High Energy Astrophysical Phenomena (astro-ph.HE) ,Physics ,[PHYS]Physics [physics] ,biology ,X-ray ,Astronomy and Astrophysics ,biology.organism_classification ,Acis ,Black hole ,Neutron star ,Space and Planetary Science ,Globular cluster ,Astrophysics - High Energy Astrophysical Phenomena ,[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] - Abstract
Globular clusters host a variety of lower-luminosity ($L_X 10^{33}$ erg s$^{-1}$. Among these moderately bright systems, we discover a new source in NGC 6539 that may be a candidate accreting stellar-mass black hole or a transitional millisecond pulsar. We show that quiescent neutron star LMXBs in globular clusters may spend ~2% of their lifetimes as transitional millisecond pulsars in their active ($L_X>10^{33}$ erg s$^{-1}$) state. Finally, we identify a substantial under-abundance of bright ($L_X>10^{33}$ erg s$^{-1}$) intermediate polars in globular clusters compared to the Galactic field, in contrast with the literature of the past two decades., 35 pages, 14 figures, ApJ, in press. The complete catalog is available in a machine-readable format via "Other formats" (source)
- Published
- 2020
15. A New Likely Redback Millisecond Pulsar Binary with a Massive Neutron Star: 4FGL J2333.1--5527
- Author
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Elias Aydi, Ryan Urquhart, Laura Shishkovsky, Jerome A. Orosz, Adam Kawash, Samuel J. Swihart, Laura Chomiuk, R. Salinas, Jay Strader, and Kristen C. Dage
- Subjects
010504 meteorology & atmospheric sciences ,Astrophysics::High Energy Astrophysical Phenomena ,Binary number ,FOS: Physical sciences ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,law.invention ,Telescope ,Pulsar ,Millisecond pulsar ,law ,Primary (astronomy) ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,0105 earth and related environmental sciences ,Physics ,High Energy Astrophysical Phenomena (astro-ph.HE) ,Inclined orbit ,Astronomy and Astrophysics ,Neutron star ,Space and Planetary Science ,Astrophysics::Earth and Planetary Astrophysics ,Astrophysics - High Energy Astrophysical Phenomena ,Fermi Gamma-ray Space Telescope - Abstract
We present the discovery of a likely new redback millisecond pulsar binary associated with the \emph{Fermi} $\gamma$-ray source 4FGL J2333.1--5527. Using optical photometric and spectroscopic observations from the SOAR telescope, we identify a low-mass, main sequence-like companion in a 6.9-hr, highly inclined orbit around a suspected massive neutron star primary. Archival XMM-Newton X-ray observations show this system has a hard power-law spectrum $\Gamma = 1.6\pm0.3$ and $L_X \sim 5 \times 10^{31}$ erg s$^{-1}$, consistent with redback millisecond pulsar binaries. Our data suggest that for secondary masses typical of redbacks, the mass of the neutron star is likely well in excess of $\sim1.4\,M_{\odot}$, but future timing of the radio pulsar is necessary to bolster this tentative conclusion. This work shows that a bevy of nearby compact binaries still await discovery, and that unusually massive neutron stars continue to be common in redbacks., Comment: Accepted to ApJ; 9 pages, 6 figures, 1 table
- Published
- 2019
16. 2FGL J0846.0+2820: A New Neutron Star Binary with a Giant Secondary and Variable gamma-Ray Emission
- Author
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Tyrel J. Johnson, Laura Chomiuk, Søren S. Larsen, Asher Wasserman, David J. Sand, Daniel E. Reichart, G. V. Simonian, Jean P. Brodie, J. B. Haislip, Samuel J. Swihart, Evangelia Tremou, Jay Strader, C. C. Cheung, and Laura Shishkovsky
- Subjects
Physics ,010308 nuclear & particles physics ,Astronomy ,Astrophysics::High Energy Astrophysical Phenomena ,Binary number ,Astronomy and Astrophysics ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,Neutron star ,Variable (computer science) ,Space and Planetary Science ,0103 physical sciences ,ComputingMethodologies_DOCUMENTANDTEXTPROCESSING ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,Astrophysics - High Energy Astrophysical Phenomena ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics - Abstract
We present optical photometric and spectroscopic observations of the likely stellar counterpart to the unassociated \emph{Fermi}-Large Area Telescope (LAT) $\gamma$-ray source 2FGL J0846.0+2820, selected for study based on positional coincidences of optical variables with unassociated LAT sources. Using optical spectroscopy from the SOAR telescope, we have identified a late-G giant in an eccentric ($e$ = 0.06) 8.133 day orbit with an invisible primary. Modeling the spectroscopy and photometry together lead us to infer a heavy neutron star primary of $\sim 2 M_{\odot}$ and a partially stripped giant secondary of $\sim 0.8 M_{\odot}$. H$\alpha$ emission is observed in some of the spectra, perhaps consistent with the presence of a faint accretion disk. We find the $\gamma$-ray flux of 2FGL J0846.0+2820 dropped substantially in mid-2009, accompanied by an increased variation in the optical brightness, and since then it has not been detected by \emph{Fermi}. The long period and giant secondary are reminiscent of the $\gamma$-ray bright binary 1FGL J1417.7--4407, which hosts a millisecond pulsar apparently in the final stages of the pulsar recycling process. The discovery of 2FGL J0846.0+2820 suggests the identification of a new subclass of millisecond pulsar binaries that are the likely progenitors of typical field millisecond pulsars., Comment: 12 pages, 8 figures, 3 tables. Accepted for publication in ApJ
- Published
- 2017
17. Observations of the Ultra-compact X-ray Binary 4U 1543-624 in Outburst with NICER, INTEGRAL, Swift, and ATCA
- Author
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Gaurava K. Jaisawal, James Miller-Jones, Edward M. Cackett, Jonah Miller, Diego Altamirano, Peter Bult, Mark Reynolds, Tod E. Strohmayer, Lorenzo Natalucci, Andrew C. Fabian, Laura Shishkovsky, Keith C. Gendreau, Mariateresa Fiocchi, Javier A. García, Sebastien Guillot, Renee M. Ludlam, Abderahmen Zoghbi, Deepto Chakrabarty, Zaven Arzoumanian, Arash Bahramian, Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Centre National d'Études Spatiales [Toulouse] (CNES), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), and Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
Accretion ,010504 meteorology & atmospheric sciences ,Astrophysics::High Energy Astrophysical Phenomena ,X-ray binary ,Binary number ,FOS: Physical sciences ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,Gravitation ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,Emission spectrum ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,0105 earth and related environmental sciences ,Line (formation) ,Physics ,High Energy Astrophysical Phenomena (astro-ph.HE) ,Accretion (meteorology) ,Plane (geometry) ,Astronomy and Astrophysics ,neutron [Stars] ,Neutron star ,13. Climate action ,Space and Planetary Science ,Accretion disks ,Astrophysics::Earth and Planetary Astrophysics ,Astrophysics - High Energy Astrophysical Phenomena ,[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] - Abstract
We report on X-ray and radio observations of the ultra-compact X-ray binary 4U 1543-624 taken in August 2017 during an enhanced accretion episode. We obtained NICER monitoring of the source over a $\sim10$ day period during which target-of-opportunity observations were also conducted with Swift, INTEGRAL, and ATCA. Emission lines were measured in the NICER X-ray spectrum at $\sim0.64$ keV and $\sim6.4$ keV that correspond to O and Fe, respectively. By modeling these line components, we are able to track changes in the accretion disk throughout this period. The innermost accretion flow appears to move inwards from hundreds of gravitational radii ($R_{g}=GM/c^{2}$) at the beginning of the outburst to $, Comment: 13 pages, 9 figures, 2 tables, accepted for publication in ApJ
- Published
- 2019
18. The MAVERIC Survey: Radio Catalogs and Source Counts from Deep Very Large Array Imaging of 25 Galactic Globular Clusters
- Author
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Jay Strader, Gregory R. Sivakoff, Vlad Tudor, Laura Shishkovsky, Thomas J. Maccarone, Laura Chomiuk, Craig O. Heinke, Arash Bahramian, James Miller-Jones, Evangelia Tremou, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)
- Subjects
High Energy Astrophysical Phenomena (astro-ph.HE) ,Physics ,Very large array ,Astrophysics::High Energy Astrophysical Phenomena ,X-ray binary ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Astrophysics - Astrophysics of Galaxies ,01 natural sciences ,010305 fluids & plasmas ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Astrophysics of Galaxies (astro-ph.GA) ,Globular cluster ,0103 physical sciences ,Source counts ,Astrophysics - High Energy Astrophysical Phenomena ,[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] ,010303 astronomy & astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,Astrophysics::Galaxy Astrophysics - Abstract
The MAVERIC survey is the first deep radio continuum imaging survey of Milky Way globular clusters, with a central goal of finding and classifying accreting compact binaries, including stellar-mass black holes. Here we present radio source catalogs for 25 clusters with ultra-deep Karl G. Jansky Very Large Array observations. The median observing time was 10 hr per cluster, resulting in typical rms sensitivities of 2.3 and 2.1 uJy per beam at central frequencies of 5.0 and 7.2 GHz, respectively. We detect nearly 1300 sources in our survey at 5 sigma, and while many of these are likely to be background sources, we also find strong evidence for an excess of radio sources in some clusters. The radio spectral index distribution of sources in the cluster cores differs from the background, and shows a bimodal distribution. We tentatively classify the steep-spectrum sources (those much brighter at 5.0 GHz) as millisecond pulsars and the flat-spectrum sources as compact or other kinds of binaries. These provisional classifications will be solidified with the future addition of X-ray and optical data. The outer regions of our images represent a deep, relatively wide field (~ 0.4/sq. deg) and high resolution C band background survey, and we present source counts calculated for this area. We also release radio continuum images for these 25 clusters to the community., published in ApJ. table 3 available as an ancillary CSV file. pending final hosting by the NRAO archive, the FITS images may be found at: https://www.dropbox.com/sh/a7a9qsqrepq5fmb/AABTtfMkftMSTUEFjzw6NU6Xa
- Published
- 2020
19. Erratum: The Swift Bulge Survey: optical and near-IR follow-up featuring a likely symbiotic X-ray binary & a focused wind CV
- Author
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A. J. Tetarenko, J. A. Kennea, L. E. Rivera Sandoval, Rudy Wijnands, Jay Strader, Arash Bahramian, G. R. Sivakoff, J. J. M. in 't Zand, Laura Shishkovsky, Craig O. Heinke, E. Kuulkers, Arne Rau, Nathalie Degenaar, Samuel J. Swihart, T. J. Maccarone, and Aarran W. Shaw
- Subjects
Physics ,Swift ,Space and Planetary Science ,Bulge ,X-ray binary ,Astronomy and Astrophysics ,Astrophysics ,computer ,computer.programming_language - Published
- 2020
20. The Maveric Survey: a Red Straggler Binary with an Invisible Companion in the Galactic Globular Cluster M10
- Author
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Thomas J. Maccarone, Laura Chomiuk, Arash Bahramian, James Miller-Jones, Gregory R. Sivakoff, Jay Strader, Vlad Tudor, R. Salinas, Laura Shishkovsky, Evangelia Tremou, K. L. Li, and Craig O. Heinke
- Subjects
Physics ,High Energy Astrophysical Phenomena (astro-ph.HE) ,010308 nuclear & particles physics ,Astrophysics::High Energy Astrophysical Phenomena ,White dwarf ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,Radio spectrum ,Luminosity ,Red-giant branch ,Black hole ,Neutron star ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Globular cluster ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,Continuum (set theory) ,Astrophysics - High Energy Astrophysical Phenomena ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) - Abstract
We present the discovery and characterization of a radio-bright binary in the Galactic globular cluster M10. First identified in deep radio continuum data from the Karl G. Jansky Very Large Array, M10-VLA1 has a flux density of $27\pm4$ $\mu$Jy at 7.4 GHz and a flat to inverted radio spectrum. Chandra imaging shows an X-ray source with $L_X \approx 10^{31}$ erg s$^{-1}$ matching the location of the radio source. This places M10-VLA1 within the scatter of the radio--X-ray luminosity correlation for quiescent stellar-mass black holes, and a black hole X-ray binary is a viable explanation for this system. The radio and X-ray properties of the source disfavor, though do not rule out, identification as an accreting neutron star or white dwarf system. Optical imaging from the Hubble Space Telescope and spectroscopy from the SOAR telescope show the system has an orbital period of 3.339 d and an unusual "red straggler" component: an evolved star found redward of M10's red giant branch. These data also show UV/optical variability and double-peaked H$\alpha$ emission characteristic of an accretion disk. However, SOAR spectroscopic monitoring reveals that the velocity semi-amplitude of the red straggler is low. We conclude that M10-VLA1 is most likely either a quiescent black hole X-ray binary with a rather face-on ($ i < $ 4$^{\circ}$) orientation or an unusual flaring RS CVn-type active binary, and discuss future observations that could distinguish between these possibilities., Comment: ApJ accepted, 13 pages, 8 figures
- Published
- 2018
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21. The MAVERIC survey: A transitional millisecond pulsar candidate in Terzan 5
- Author
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Vlad Tudor, Gregory R. Sivakoff, Nathalie Degenaar, Scott M. Ransom, Thomas J. Maccarone, Laura Chomiuk, Rudy Wijnands, Alexandra J. Tetarenko, Evangelia Tremou, James Miller-Jones, Arash Bahramian, Jay Strader, Laura Shishkovsky, Craig O. Heinke, Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), and High Energy Astrophys. & Astropart. Phys (API, FNWI)
- Subjects
Brightness ,Astrophysics::High Energy Astrophysical Phenomena ,Continuum (design consultancy) ,FOS: Physical sciences ,Binary number ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,Luminosity ,X-rays: binaries ,stars: neutron ,Pulsar ,accretion ,Millisecond pulsar ,0103 physical sciences ,010303 astronomy & astrophysics ,High Energy Astrophysical Phenomena (astro-ph.HE) ,Physics ,Millisecond ,010308 nuclear & particles physics ,accretion disks ,Astrophysics::Instrumentation and Methods for Astrophysics ,Astronomy and Astrophysics ,Space and Planetary Science ,Globular cluster ,Astrophysics - High Energy Astrophysical Phenomena ,[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] ,globular clusters: individual - Abstract
Transitional millisecond pulsars are accreting millisecond pulsars that switch between accreting X-ray binary and millisecond radio pulsar states. Only a handful of these objects have been identified so far. Terzan 5 CX1 is a variable hard X-ray source in the globular cluster Terzan 5. In this paper, we identify a radio counterpart to CX1 in deep Very Large Array radio continuum data. Chandra observations over the last fourteen years indicate that CX1 shows two brightness states: in 2003 and 2016 the source was the brightest X-ray source in the cluster (at L$_X \sim 10^{33}$ erg s$^{-1}$), while in many intermediate observations, its luminosity was almost an order of magnitude lower. We analyze all available X-ray data of CX1, showing that the two states are consistent with the spectral and variability properties observed for the X-ray active and radio pulsar states of known transitional millisecond pulsars. Finally, we discuss the prospects for the detection of CX1 as a radio pulsar in existing timing data., Comment: 14 pages, 6 figures, ApJ, in press
- Published
- 2018
22. A multi-wavelength view of the neutron star binary 1FGL J1417.7--4402: A progenitor to canonical millisecond pulsars
- Author
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Craig O. Heinke, C. C. Cheung, Laura Chomiuk, Arash Bahramian, James Miller-Jones, Samuel J. Swihart, Laura Shishkovsky, Philip G. Edwards, and Jay Strader
- Subjects
Physics ,High Energy Astrophysical Phenomena (astro-ph.HE) ,Astrophysics::High Energy Astrophysical Phenomena ,Binary number ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,Neutron star ,Space and Planetary Science ,Millisecond pulsar ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,010306 general physics ,Astrophysics - High Energy Astrophysical Phenomena ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics - Abstract
The Fermi $\gamma$-ray source 1FGL J1417.7--4407 (J1417) is a compact X-ray binary with a neutron star primary and a red giant companion in a $\sim$5.4 day orbit. This initial conclusion, based on optical and X-ray data, was confirmed when a 2.66 ms radio pulsar was found at the same location (and with the same orbital properties) as the optical/X-ray source. However, these initial studies found conflicting evidence about the accretion state and other properties of the binary. We present new optical, radio, and X-ray observations of J1417 that allow us to better understand this unusual system. We show that one of the main pieces of evidence previously put forward for an accretion disk---the complex morphology of the persistent H$\alpha$ emission line---can be better explained by the presence of a strong, magnetically driven stellar wind from the secondary and its interaction with the pulsar wind. The radio spectral index derived from VLA/ATCA observations is broadly consistent with that expected from a millisecond pulsar, further disfavoring an accretion disk scenario. X-ray observations show evidence for a double-peaked orbital light curve, similar to that observed in some redback millisecond pulsar binaries and likely due to an intrabinary shock. Refined optical light curve fitting gives a distance of 3.1$\pm$0.6 kpc, confirmed by a Gaia DR2 parallax measurement. At this distance the X-ray luminosity of J1417 is (1.0$^{+0.4}_{-0.3}$) $\times 10^{33}$ erg s$^{-1}$, which is more luminous than all known redback systems in the rotational-powered pulsar state, perhaps due to the wind from the giant companion. The unusual phenomenology of this system and its differing evolutionary path from redback millisecond pulsar binaries points to a new eclipsing pulsar "spider" subclass that is a possible progenitor of normal field millisecond pulsar binaries., Comment: 14 pages, 7 figures, 6 tables, Accepted for publication in ApJ
- Published
- 2018
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23. A new γ-ray loud, eclipsing low-mass X-ray binary
- Author
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Craig O. Heinke, Andrzej Udalski, Mark B. Peacock, Kwan-Lok Li, Laura Shishkovsky, Laura Chomiuk, Evangelia Tremou, and Jay Strader
- Subjects
Astrophysics::High Energy Astrophysical Phenomena ,X-ray binary ,FOS: Physical sciences ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,Pulsar ,Millisecond pulsar ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,Emission spectrum ,010303 astronomy & astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,Astrophysics::Galaxy Astrophysics ,Physics ,High Energy Astrophysical Phenomena (astro-ph.HE) ,010308 nuclear & particles physics ,Astronomy and Astrophysics ,Light curve ,Radial velocity ,Neutron star ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Astrophysics::Earth and Planetary Astrophysics ,Astrophysics - High Energy Astrophysical Phenomena ,Fermi Gamma-ray Space Telescope - Abstract
We report the discovery of an eclipsing low-mass X-ray binary at the center of the 3FGL error ellipse of the unassociated Fermi/Large Area Telescope gamma-ray source 3FGL J0427.9-6704. Photometry from OGLE and the SMARTS 1.3-m telescope and spectroscopy from the SOAR telescope have allowed us to classify the system as an eclipsing low-mass X-ray binary (P = 8.8 hr) with a main sequence donor and a neutron star accretor. Broad double-peaked H and He emission lines suggest the ongoing presence of an accretion disk. Remarkably, the system shows shows separate sets of absorption lines associated with the accretion disk and the secondary, and we use their radial velocities to find evidence for a massive (~ 1.8-1.9 M_sun) neutron star primary. In addition to a total X-ray eclipse of duration ~ 2200 s observed with NuSTAR, the X-ray light curve also shows properties similar to those observed among known transitional millisecond pulsars: short-term variability, a hard power-law spectrum (photon index ~ 1.7), and a comparable 0.5-10 keV luminosity (~ 2.4 x 10^33 erg/s). We find tentative evidence for a partial (~ 60%) gamma-ray eclipse at the same phase as the X-ray eclipse, suggesting the gamma-ray emission may not be confined to the immediate region of the compact object. The favorable inclination of this binary is promising for future efforts to determine the origin of gamma-rays among accreting neutron stars., Comment: ApJ in press
- Published
- 2016
24. Optical Spectroscopy and Demographics of Redback Millisecond Pulsar Binaries
- Author
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Jerome A. Orosz, Christopher T. Britt, Arash Bahramian, Jay Strader, R. Salinas, Samuel J. Swihart, Evangelia Tremou, Mark B. Peacock, C. C. Cheung, Kristen C. Dage, Roberto Mignani, Laura Shishkovsky, Laura Chomiuk, K. L. Li, Jules P. Halpern, Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), and Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)
- Subjects
010504 meteorology & atmospheric sciences ,Astrophysics::High Energy Astrophysical Phenomena ,FOS: Physical sciences ,Context (language use) ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,gamma rays: stars ,01 natural sciences ,Luminosity ,stars: neutron ,X-rays: binaries ,Pulsar ,Millisecond pulsar ,pulsars: general ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,Spectroscopy ,010303 astronomy & astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,Astrophysics::Galaxy Astrophysics ,0105 earth and related environmental sciences ,High Energy Astrophysical Phenomena (astro-ph.HE) ,Physics ,Sigma ,Astronomy and Astrophysics ,Radial velocity ,Neutron star ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Astrophysics::Earth and Planetary Astrophysics ,[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] ,Astrophysics - High Energy Astrophysical Phenomena ,binaries: spectroscopic - Abstract
We present the first optical spectroscopy of five confirmed (or strong candidate) redback millisecond pulsar binaries, obtaining complete radial velocity curves for each companion star. The properties of these millisecond pulsar binaries with low-mass, hydrogen-rich companions are discussed in the context of the 14 confirmed and 10 candidate field redbacks. We find that the neutron stars in redbacks have a median mass of 1.78 +/- 0.09 M_sun with a dispersion of sigma = 0.21 +/- 0.09. Neutron stars with masses in excess of 2 M_sun are consistent with, but not firmly demanded by, current observations. Redback companions have median masses of 0.36 +/- 0.04 M_sun with a scatter of sigma = 0.15 +/- 0.04, and a tail possibly extending up to 0.7-0.9 M_sun. Candidate redbacks tend to have higher companion masses than confirmed redbacks, suggesting a possible selection bias against the detection of radio pulsations in these more massive candidate systems. The distribution of companion masses between redbacks and the less massive black widows continues to be strongly bimodal, which is an important constraint on evolutionary models for these systems. Among redbacks, the median efficiency of converting the pulsar spindown energy to gamma-ray luminosity is ~10%., Apj in press. Long/large tables 6 and 7 also included as ancillary machine-readable files; numbering different from published version for ease of use
- Published
- 2019
25. The MAVERIC Survey: Still No Evidence for Accreting Intermediate-mass Black Holes in Globular Clusters
- Author
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Thomas J. Maccarone, Laura Chomiuk, Gregory R. Sivakoff, Evangelia Tremou, Vlad Tudor, Anil C. Seth, Laura Shishkovsky, Jay Strader, Craig O. Heinke, Eva Noyola, and James Miller-Jones
- Subjects
High Energy Astrophysical Phenomena (astro-ph.HE) ,Physics ,Very large array ,010308 nuclear & particles physics ,Astrophysics::High Energy Astrophysical Phenomena ,Continuum (design consultancy) ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,01 natural sciences ,Accretion (astrophysics) ,law.invention ,Telescope ,Black hole ,Space and Planetary Science ,law ,Globular cluster ,0103 physical sciences ,Cluster (physics) ,Astrophysics - High Energy Astrophysical Phenomena ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics - Abstract
We present the results of an ultra-deep, comprehensive radio continuum survey for the accretion signatures of intermediate-mass black holes in globular clusters. The sample, imaged with the Karl G.~Jansky Very Large Array and the Australia Telescope Compact Array, comprises 50 Galactic globular clusters. No compelling evidence for an intermediate-mass black hole is found in any cluster in our sample. In order to achieve the highest sensitivity to low-level emission, we also present the results of an overall stack of our sample, as well as various subsamples, also finding non-detections. These results strengthen the idea that intermediate-mass black holes with masses $\gtrsim 1000 M_{\odot}$ are rare or absent in globular clusters., Comment: 27 pages, 7 figures, 2 tables. Accepted for publication in ApJ
- Published
- 2018
26. A New Likely Redback Millisecond Pulsar Binary with a Massive Neutron Star: 4FGL J2333.1–5527.
- Author
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Samuel J. Swihart, Jay Strader, Ryan Urquhart, Jerome A. Orosz, Laura Shishkovsky, Laura Chomiuk, Ricardo Salinas, Elias Aydi, Kristen C. Dage, and Adam M. Kawash
- Subjects
SUPERGIANT stars ,NEUTRON stars ,BINARY pulsars ,X-ray binaries ,STELLAR mass ,PULSARS - Abstract
We present the discovery of a likely new redback millisecond pulsar (MSP) binary associated with the Fermi γ-ray source 4FGL J2333.1–5527. Using optical photometric and spectroscopic observations from the Southern Astrophysical Research telescope, we identify a low-mass, main-sequence-like companion in a 6.9 hr, highly inclined orbit around a suspected massive neutron star primary. Archival XMM-Newton X-ray observations show this system has a hard power-law spectrum Γ = 1.6 ± 0.3 and L
X ∼ 5 × 1031 erg s−1 , consistent with redback MSP binaries. Our data suggest that for secondary masses typical of redbacks, the mass of the neutron star is likely well in excess of ∼1.4 M⊙ , but future timing of the radio pulsar is necessary to bolster this tentative conclusion. This work shows that a bevy of nearby compact binaries still await discovery, and that unusually massive neutron stars continue to be common in redbacks. [ABSTRACT FROM AUTHOR]- Published
- 2020
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27. Optical Spectroscopy and Demographics of Redback Millisecond Pulsar Binaries.
- Author
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Jay Strader, Samuel Swihart, Laura Chomiuk, Arash Bahramian, Chris Britt, C. C. Cheung, Kristen Dage, Jules Halpern, Kwan-Lok Li, Roberto P. Mignani, Jerome A. Orosz, Mark Peacock, Ricardo Salinas, Laura Shishkovsky, and Evangelia Tremou
- Subjects
OPTICAL spectroscopy ,RADIAL velocity of stars ,PULSARS ,BINARY stars ,HYDROGEN - Abstract
We present the first optical spectroscopy of five confirmed (or strong candidate) redback millisecond pulsar binaries, obtaining complete radial velocity curves for each companion star. The properties of these millisecond pulsar binaries with low-mass, hydrogen-rich companions are discussed in the context of the 14 confirmed and 10 candidate field redbacks. We find that the neutron stars in redbacks have a median mass of 1.78 ± 0.09 M
⊙ with a dispersion of σ = 0.21 ± 0.09. Neutron stars with masses in excess of 2 M⊙ are consistent with, but not firmly demanded by, current observations. Redback companions have median masses of 0.36 ± 0.04 M⊙ with a scatter of σ = 0.15 ± 0.04 M⊙ , and a tail possibly extending up to 0.7–0.9 M⊙ . Candidate redbacks tend to have higher companion masses than confirmed redbacks, suggesting a possible selection bias against the detection of radio pulsations in these more massive candidate systems. The distribution of companion masses between redbacks and the less massive black widows continues to be strongly bimodal, which is an important constraint on evolutionary models for these systems. Among redbacks, the median efficiency of converting the pulsar spin-down energy to γ-ray luminosity is ∼10%. [ABSTRACT FROM AUTHOR]- Published
- 2019
- Full Text
- View/download PDF
28. A Multiwavelength View of the Neutron Star Binary 1FGL J1417.7–4402: A Progenitor to Canonical Millisecond Pulsars.
- Author
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Samuel J. Swihart, Jay Strader, Laura Shishkovsky, Laura Chomiuk, Arash Bahramian, Craig O. Heinke, James C. A. Miller-Jones, Philip G. Edwards, and C. C. Cheung
- Subjects
NEUTRON stars ,BINARY stars ,PULSARS ,RED giants ,X-ray spectra - Abstract
The Fermi γ-ray source 1FGL J1417.7–4407 (J1417) is a compact X-ray binary with a neutron star primary and a red giant companion in a ∼5.4 days orbit. This initial conclusion, based on optical and X-ray data, was confirmed when a 2.66 ms radio pulsar was found at the same location (and with the same orbital properties) as the optical/X-ray source. However, these initial studies found conflicting evidence about the accretion state and other properties of the binary. We present new optical, radio, and X-ray observations of J1417 that allow us to better understand this unusual system. We show that one of the main pieces of evidence previously put forward for an accretion disk—the complex morphology of the persistent Hα emission line—can be better explained by the presence of a strong, magnetically driven stellar wind from the secondary and its interaction with the pulsar wind. The radio spectral index derived from VLA/ATCA observations is broadly consistent with that expected from a millisecond pulsar, further disfavoring an accretion disk scenario. X-ray observations show evidence for a double-peaked orbital light curve, similar to that observed in some redback millisecond pulsar binaries and likely due to an intrabinary shock. Refined optical light-curve fitting gives a distance of 3.1 ± 0.6 kpc, confirmed by a Gaia DR2 parallax measurement. At this distance the X-ray luminosity of J1417 is () ×10
33 erg s−1 , which is more luminous than all known redback systems in the rotational-powered pulsar state, perhaps due to the wind from the giant companion. The unusual phenomenology of this system and its differing evolutionary path from redback millisecond pulsar binaries points to a new eclipsing pulsar “spider” subclass that is a possible progenitor of normal field millisecond pulsar binaries. [ABSTRACT FROM AUTHOR]- Published
- 2018
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- View/download PDF
29. The MAVERIC Survey: A Transitional Millisecond Pulsar Candidate in Terzan 5.
- Author
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Arash Bahramian, Jay Strader, Laura Chomiuk, Craig O. Heinke, James C. A. Miller-Jones, Nathalie Degenaar, Alexandra J. Tetarenko, Vlad Tudor, Evangelia Tremou, Laura Shishkovsky, Rudy Wijnands, Thomas J. Maccarone, Gregory R. Sivakoff, and Scott Ransom
- Subjects
PULSARS ,X-ray binaries ,ACCRETION (Astrophysics) ,VERY large array telescopes ,GLOBULAR clusters ,HARD X-rays - Abstract
Transitional millisecond pulsars are accreting millisecond pulsars that switch between accreting X-ray binary and millisecond radio pulsar states. Only a handful of these objects have been identified so far. Terzan 5 CX1 is a variable hard-X-ray source in the globular cluster Terzan 5. In this paper, we identify a radio counterpart to CX1 in deep Very Large Array radio continuum data. Chandra observations over the last 14 years indicate that CX1 shows two brightness states: in 2003 and 2016 the source was the brightest X-ray source in the cluster (at L
X ∼ 1033 erg s−1 ), while in many intermediate observations, its luminosity was almost an order of magnitude lower. We analyze all available X-ray data of CX1, showing that the two states are consistent with the spectral and variability properties observed for the X-ray active and radio pulsar states of known transitional millisecond pulsars. Finally, we discuss the prospects for the detection of CX1 as a radio pulsar in existing timing data. [ABSTRACT FROM AUTHOR]- Published
- 2018
- Full Text
- View/download PDF
30. The MAVERIC Survey: Still No Evidence for Accreting Intermediate-mass Black Holes in Globular Clusters.
- Author
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Evangelia Tremou, Jay Strader, Laura Chomiuk, Laura Shishkovsky, Thomas J. Maccarone, James C. A. Miller-Jones, Vlad Tudor, Craig O. Heinke, Gregory R. Sivakoff, Anil C. Seth, and Eva Noyola
- Subjects
STELLAR black holes ,GLOBULAR clusters ,STELLAR mass ,VERY large array telescopes ,ACCRETION (Astrophysics) - Abstract
We present the results of an ultradeep, comprehensive radio continuum survey for the accretion signatures of intermediate-mass black holes (IMBHs) in globular clusters (GCs). The sample, imaged with the Karl G. Jansky Very Large Array and the Australia Telescope Compact Array, comprises 50 Galactic GCs. No compelling evidence for an IMBH is found in any cluster in our sample. In order to achieve the highest sensitivity to low-level emission, we also present the results of an overall stack of our sample as well as various subsamples, also finding nondetections. These results strengthen the idea that IMBHs with masses ≳1000M
⊙ are rare or absent in GCs. [ABSTRACT FROM AUTHOR]- Published
- 2018
- Full Text
- View/download PDF
31. The MAVERIC Survey: A Red Straggler Binary with an Invisible Companion in the Galactic Globular Cluster M10.
- Author
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Laura Shishkovsky, Jay Strader, Laura Chomiuk, Arash Bahramian, Evangelia Tremou, Kwan-Lok Li, Ricardo Salinas, Vlad Tudor, James C. A. Miller-Jones, Thomas J. Maccarone, Craig O. Heinke, and Gregory R. Sivakoff
- Subjects
- *
GALACTIC dynamics , *STELLAR black holes , *BINARY stars , *DWARF galaxies - Abstract
We present the discovery and characterization of a radio-bright binary in the Galactic globular cluster M10. First identified in deep radio continuum data from the Karl G. Jansky Very Large Array, M10-VLA1 has a flux density of 27 ± 4 μJy at 7.4 GHz and a flat-to-inverted radio spectrum. Chandra imaging shows an X-ray source with LX ≈ 1031 erg s−1 matching the location of the radio source. This places M10-VLA1 within the scatter of the radio-X-ray luminosity correlation for quiescent stellar-mass black holes, and a black hole X-ray binary is a viable explanation for this system. The radio and X-ray properties of the source disfavor, but do not rule out, identification as an accreting neutron star or white dwarf system. Optical imaging from the Hubble Space Telescope and spectroscopy from the SOAR telescope show that the system has an orbital period of 3.339 days and an unusual “red straggler” component: an evolved star found redward of the M10 red giant branch. These data also show UV/optical variability and double-peaked Hα emission characteristic of an accretion disk. However, SOAR spectroscopic monitoring reveals that the velocity semi-amplitude of the red straggler is low. We conclude that M10-VLA1 is most likely either a quiescent black hole X-ray binary with a rather face-on (i < 4°) orientation or an unusual flaring RS Canum Venaticorum variable-type active binary, and discuss future observations that could distinguish between these possibilities. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
32. 2FGL J0846.0+2820: A New Neutron Star Binary with a Giant Secondary and Variable γ-Ray Emission.
- Author
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Samuel J. Swihart, Jay Strader, Tyrel J. Johnson, C. C. Cheung, David Sand, Laura Chomiuk, Asher Wasserman, Søren Larsen, Jean P. Brodie, Gregory V. Simonian, Evangelia Tremou, Laura Shishkovsky, Daniel E. Reichart, and Joshua Haislip
- Subjects
BINARY stars ,SPECTROSCOPIC light sources ,GAMMA ray polarization ,ASTRONOMICAL observations ,SOLAR system ,STAR formation - Abstract
We present optical photometric and spectroscopic observations of the likely stellar counterpart to the unassociated Fermi Large Area Telescope (LAT) γ-ray source 2FGL J0846.0+2820, selected for study based on positional coincidences of optical variables with unassociated LAT sources. Using optical spectroscopy from the SOAR telescope, we have identified a late-G giant in an eccentric (e = 0.06) 8.133-day orbit with an invisible primary. Modeling the spectroscopy and photometry together led us to infer a heavy neutron star primary of and a partially stripped giant secondary of . Hα emission is observed in some of the spectra, perhaps consistent with the presence of a faint accretion disk. We find that the γ-ray flux of 2FGL J0846.0+2820 dropped substantially in mid-2009, accompanied by an increased variation in the optical brightness, and since then, it has not been detected by Fermi. The long period and giant secondary are reminiscent of the γ-ray bright binary 1FGL J1417.7–4407, which hosts a millisecond pulsar (MSP) apparently in the final stages of the pulsar recycling process. The discovery of 2FGL J0846.0+2820 suggests the identification of a new subclass of MSP binaries that are the likely progenitors of typical field MSPs. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
33. A NEW γ-RAY LOUD, ECLIPSING LOW-MASS X-RAY BINARY.
- Author
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Jay Strader, Kwan-Lok Li, Laura Chomiuk, Craig O. Heinke, Andrzej Udalski, Mark Peacock, Laura Shishkovsky, and Evangelia Tremou
- Subjects
DUAL-energy X-ray absorptiometry ,TELESCOPES ,ACCRETION disks ,BINARY stars ,RADIAL velocity of stars ,SPECTRUM analysis - Abstract
We report the discovery of an eclipsing low-mass X-ray binary at the center of the 3FGL error ellipse of the unassociated Fermi/Large Area Telescope γ-ray source 3FGL J0427.9–6704. Photometry from OGLE and the SMARTS 1.3 m telescope and spectroscopy from the SOAR telescope have allowed us to classify the system as an eclipsing low-mass X-ray binary (P = 8.8 hr) with a main-sequence donor and a neutron-star accretor. Broad double-peaked H and He emission lines suggest the ongoing presence of an accretion disk. Remarkably, the system shows separate sets of absorption lines associated with the accretion disk and the secondary, and we use their radial velocities to find evidence for a massive (∼1.8–1.9 M
⊙ ) neutron-star primary. In addition to a total X-ray eclipse with a duration of ∼2200 s observed with NuSTAR, the X-ray light curve also shows properties similar to those observed among known transitional millisecond pulsars: short-term variability, a hard power-law spectrum (), and a comparable 0.5–10 keV luminosity ( erg s−1 ). We find tentative evidence for a partial () γ-ray eclipse at the same phase as the X-ray eclipse, suggesting the γ-ray emission may not be confined to the immediate region of the compact object. The favorable inclination of this binary is promising for future efforts to determine the origin of γ-rays among accreting neutron stars. [ABSTRACT FROM AUTHOR]- Published
- 2016
- Full Text
- View/download PDF
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