169 results on '"F. E. Marshall"'
Search Results
2. Short gamma-ray bursts within 200 Mpc
- Author
-
S Dichiara, E Troja, B O’Connor, F E Marshall, P Beniamini, J K Cannizzo, A Y Lien, and T Sakamoto
- Published
- 2020
- Full Text
- View/download PDF
3. Swift Multiwavelength Follow-up of LVC S200224ca and the Implications for Binary Black Hole Mergers
- Author
-
N J Klinger, A Lien, S R Oates, J A Kennea, P A Evans, A Tohuvavohu, B Zhang, K L Page, S B Cenko, S D Barthelmy, A P Beardmore, M G Bernardini, A A Breeveld, P J Brown, D N Burrows, S Campana, G Cusumano, A D'Ai, P D'Avanzo, V D'Elia, M de Pasquale, S W K Emery, J Garcia, P Giommi, C Gronwall, D H Hartmann, H A Krimm, N P M Kuin, D B Malesani, F E Marshall, A Melandri, J A Nousek, P T O'Brien, J P Osborne, D M Palmer, M J Page, M Perri, J L Racusin, T Sakamoto, B Sbarufatti, J E Schlieder, M H Siegel, G Tagliaferri, and E Troja
- Subjects
Astronomy - Abstract
On 2020 February 24, during their third observing run (“O3”), the Laser Interferometer Gravitational-wave Observatory and Virgo Collaboration detected S200224ca: a candidate gravitational wave (GW) event produced by a binary black hole (BBH) merger. This event was one of the best-localized compact binary coalescences detected in O3 (with 50%/90% error regions of 13/72 deg2), and so the Neil Gehrels Swift Observatory performed rapid near-UV/X-ray follow-up observations. Swift-XRT and UVOT covered approximately 79.2% and 62.4% (respectively) of the GW error region, making S200224ca the BBH event most thoroughly followed-up in near-UV (u-band) and X-ray to date. No likely EM counterparts to the GW event were found by the Swift BAT, XRT, or UVOT, nor by other observatories. Here, we report on the results of our searches for an EM counterpart, both in the BAT data near the time of the merger, and in follow-up UVOT/XRT observations. We also discuss the upper limits we can place on EM radiation from S200224ca, as well as the implications these limits have on the physics of BBH mergers. Namely, we place a shallow upper limit on the dimensionless BH charge, qˆ < 1.4 x 10-4, and an upper limit on the isotropic-equivalent energy of a blast wave E<4.1×1051 erg (assuming typical GRB parameters).
- Published
- 2021
- Full Text
- View/download PDF
4. Swift-XRT Follow-up of Gravitational-wave Triggers in the Second Advanced LIGO/Virgo Observing Run
- Author
-
N. J. Klingler, J. A. Kennea, P. A. Evans, A. Tohuvavohu, S. B. Cenko, S. D. Barthelmy, A. P. Beardmore, A. A. Breeveld, P. J. Brown, D. N. Burrows, S. Campana, G. Cusumano, A. D'Aì, P. D’Avanzo, V. D’Elia, M. de Pasquale, S. W. K. Emery, J. Garcia, P. Giommi, C. Gronwall, D. H. Hartmann, H. A. Krimm, N. P. M. Kuin, A. Lien, D. B. Malesani, F. E. Marshall, A. Melandri, J. A. Nousek, S. R. Oates, P. T. O’Brien, J. P. Osborne, K. L. Page, D. M. Palmer, M. Perri, J. L. Racusin, M. H. Siegel, T. Sakamoto, B. Sbarufatti, Gianpiero Tagliaferri, and E. Troja
- Subjects
Astrophysics ,Astronomy - Abstract
The Neil Gehrels Swift Observatory carried out prompt searches for gravitational-wave (GW) events detected by the LIGO/Virgo Collaboration (LVC) during the second observing run ("O2"). Swift performed extensive tiling of eight LVC triggers, two of which had very low false-alarm rates (GW170814 and the epochal GW170817), indicating a high confidence of being astrophysical in origin; the latter was the first GW event to have an electromagnetic counterpart detected. In this paper we describe the follow-up performed during O2 and the results of our searches. No GW electromagnetic counterparts were detected; this result is expected, as GW170817 remained the only astrophysical event containing at least one neutron star after LVC's later retraction of some events. A number of X-ray sources were detected, with the majority of identified sources being active galactic nuclei. We discuss the detection rate of transient X-ray sources and their implications in the O2 tiling searches. Finally, we describe the lessons learned during O2 and how these are being used to improve the Swift follow-up of GW events. In particular, we simulate a population of gamma-ray burst afterglows to evaluate our source ranking system's ability to differentiate them from unrelated and uncataloged X-ray sources. We find that ≈60%–70% of afterglows whose jets are oriented toward Earth will be given high rank (i.e., "interesting" designation) by the completion of our second follow-up phase (assuming that their location in the sky was observed), but that this fraction can be increased to nearly 100% by performing a third follow-up observation of sources exhibiting fading behavior.
- Published
- 2019
- Full Text
- View/download PDF
5. Significant and Variable Linear Polarization During the Prompt Optical Flash of GRB 160625B
- Author
-
E Troja, V M Lipunov, C G Mundell, N R Butler, A M Watson, S Kobayashi, S B Cenko, F E Marshall, R Ricci, A Fruchter, M H Wieringa, E S Gorbovskoy, V Kornilov, A Kutyrev, W H Lee, V Toy, N V Tyurina, N M Budnev, D A H Buckley, J González, O Gress, A Horesh, M I Panasyuk, J X Prochaska, E Ramirez-Ruiz, R Rebolo Lopez, M G Richer, C Román-Zúñiga, M Serra-Ricart, V Yurkov, and N Gehrels
- Subjects
Astrophysics - Abstract
Measurement of polarized light provides a direct probe of magnetic fields in collimated outflows (jets) of relativistic plasma from accreting stellar-mass black holes at cosmological distances. These outflows power brief and intense flashes of prompt gamma-rays known as Gamma Ray Bursts (GRBs), followed by longer-lived afterglow radiation detected across the electromagnetic spectrum. Rapid-response polarimetric observations of newly discovered GRBs have probed the initial afterglow phase. Linear polarization degrees as high as Π∼30% are detected minutes after the end of the prompt GRB emission, consistent with a stable, globally ordered magnetic field permeating the jet at large distances from the central source. In contrast, optical and gamma-ray observations during the prompt phase led to discordant and often controversial results, and no definitive conclusions on the origin of the prompt radiation or the configuration of the magnetic field could be derived. Here we report the detection of linear polarization of a prompt optical flash that accompanied the extremely energetic and long-lived prompt gamma-ray emission from GRB 160625B. Our measurements probe the structure of the magnetic field at an early stage of the GRB jet, closer to the central source, and show that the prompt GRB phase is produced via fast cooling synchrotron radiation in a large-scale magnetic field advected from the central black hole and distorted from dissipation processes within the jet.
- Published
- 2017
- Full Text
- View/download PDF
6. Intensive disc-reverberation mapping of Fairall 9
- Author
-
S. Valenti, A. A. Breeveld, W. N. Brandt, J. M. Gelbord, D. A. Starkey, M. H. Siegel, Marianne Vestergaard, K. L. Page, Bradley M. Peterson, Dirk Grupe, Christopher A. Onken, Kirk T. Korista, S. J. Laporte, E. Dalla Bontà, D. Mudd, Smita Mathur, Phil Uttley, Aaron J. Barth, Michael D. Joner, P. A. Evans, Gerard A. Kriss, Hagai Netzer, D. Gonzalez-Buitrago, J. V. Hernández Santisteban, M. R. Goad, Gary J. Ferland, T. Schmidt, Susanna Bisogni, Anne M. Lohfink, Keith Horne, Rick Edelson, Edward M. Cackett, S. B. Cenko, Simon Vaughan, Missagh Mehdipour, F. E. Marshall, ITA, USA, GBR, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
- Subjects
ACTIVE GALACTIC NUCLEI ,CONTINUUM EMISSION ,Astrophysics::High Energy Astrophysical Phenomena ,individual: Fairall 9 [quasars] ,BROAD-LINE REGION ,SOFTWARE ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,Spectral line ,law.invention ,Telescope ,symbols.namesake ,VIEW ,Observatory ,law ,0103 physical sciences ,DISTRIBUTIONS ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,LAGS ,Physics ,010308 nuclear & particles physics ,Balmer series ,Astronomy and Astrophysics ,Quasar ,Light curve ,VARIABILITY ,Space and Planetary Science ,active [galaxies] ,X-RAY ,symbols ,Reverberation mapping ,Spectral energy distribution ,accretion, accretion discs ,ACCRETION DISC - Abstract
We present results of time-series analysis of the first year of the Fairall 9 intensive disc-reverberation campaign. We used Swift and the Las Cumbres Observatory global telescope network to continuously monitor Fairall 9 from X-rays to near-infrared at a daily to subdaily cadence. The cross-correlation function between bands provides evidence for a lag spectrum consistent with the τ ∝ λ4/3 scaling expected for an optically thick, geometrically thin blackbody accretion disc. Decomposing the flux into constant and variable components, the variable component’s spectral energy distribution is slightly steeper than the standard accretion disc prediction. We find evidence at the Balmer edge in both the lag and flux spectra for an additional bound-free continuum contribution that may arise from reprocessing in the broad-line region. The inferred driving light curve suggests two distinct components, a rapidly variable (100 d) component with an opposite lag to the reverberation signal.
- Published
- 2020
7. Swift-XRT follow-up of gravitational wave triggers during the third aLIGO/Virgo observing run
- Author
-
M. H. Siegel, J. A. Kennea, M. J. Page, E. Troja, Dieter H. Hartmann, B. Sbarufatti, P. T. O'Brien, M. Perri, T. Sakamoto, Regina Caputo, S. R. Oates, Phil Evans, N. P. M. Kuin, P. D'Avanzo, Hans A. Krimm, D. Malesani, Paolo Giommi, Valerio D'Elia, Peter J. Brown, N. J. Klingler, Scott Barthelmy, Giancarlo Cusumano, S. B. Cenko, J. L. Racusin, M. G. Bernardini, Sergio Campana, David Palmer, M. de Pasquale, E. Ambrosi, C. Pagani, A. Melandri, David N. Burrows, S. W. K. Emery, J. A. Nousek, A. A. Breeveld, Antonino D'Ai, Caryl Gronwall, F. E. Marshall, Gianpiero Tagliaferri, A. P. Beardmore, Joshua E. Schlieder, A. Tohuvavohu, J. P. Osborne, and K. L. Page
- Subjects
High Energy Astrophysical Phenomena (astro-ph.HE) ,Physics ,Gravitational wave ,FOS: Physical sciences ,Binary number ,Astronomy and Astrophysics ,Astrophysics ,LIGO ,Neutron star ,Wavelength ,Binary black hole ,Space and Planetary Science ,Observatory ,general [X-rays] ,ROSAT ,Astrophysics - High Energy Astrophysical Phenomena - Abstract
The Neil Gehrels Swift Observatory followed up 18 gravitational wave (GW) triggers from the LIGO/Virgo collaboration during the O3 observing run in 2019/2020, performing approximately 6500 pointings in total. Of these events, four were finally classified (if real) as binary black hole (BH) triggers, six as binary neutron star (NS) events, two each of NSBH and Mass Gap triggers, one an unmodelled (Burst) trigger, and the remaining three were subsequently retracted. Thus far, four of these O3 triggers have been formally confirmed as real gravitational wave events. While no likely electromagnetic counterparts to any of these GW events have been identified in the X-ray data (to an average upper limit of 3.60 x 10^{-12} erg cm^{-2} s^{-1} over 0.3-10 keV), or at other wavelengths, we present a summary of all the Swift-XRT observations performed during O3, together with typical upper limits for each trigger observed. The majority of X-ray sources detected during O3 were previously uncatalogued; while some of these will be new (transient) sources, others are simply too faint to have been detected by earlier survey missions such as ROSAT. The all-sky survey currently being performed by eROSITA will be a very useful comparison for future observing runs, reducing the number of apparent candidate X-ray counterparts by up to 95 per cent., Comment: 23 pages (including 4 pages of references, and a 4 page table in the appendix), 5 figures (4 in colour), accepted for publication in MNRAS. (Replaced due to annoying spelling typo in the abstract.)
- Published
- 2020
8. Swift follow-up of gravitational wave triggers: results from the first aLIGO run and optimization for the future
- Author
-
P. A. Evans, J. A. Kennea, D. M. Palmer, M. Bilicki, J. P. Osborne, P. T. O'Brien, N. R. Tanvir, A. Y. Lien, S. D. Barthelmy, D. N. Burrows, S. Campana, S. B. Cenko, V. D'Elia, N. Gehrels, F. E. Marshall, K. L. Page, M. Perri, B. Sbarufatti, M. H. Siegel, G. Tagliaferri, and E. Troja
- Subjects
Astronomy - Abstract
During its first observing run, in late 2015, the advanced Laser Interferometer Gravitational-wave Observatory facility announced three gravitational wave (GW) triggers to electromagnetic follow-up partners. Two of these have since been confirmed as being of astrophysical origin: both are binary black hole mergers at ∼500 Mpc; the other trigger was later found not to be astrophysical. In this paper, we report on the Swift follow-up observations of the second and third triggers, including details of 21 X-ray sources detected; none of which can be associated with the GW event. We also consider the challenges that the next GW observing run will bring as the sensitivity and hence typical distance of GW events will increase. We discuss how to effectively use galaxy catalogues to prioritize areas for follow-up, especially in the presence of distance estimates from the GW data. We also consider two galaxy catalogues and suggest that the high completeness at larger distances of the 2MASS Photometric Redshift catalogue makes it very well suited to optimize Swift follow-up observations.
- Published
- 2016
- Full Text
- View/download PDF
9. OUP accepted manuscript
- Author
-
Oleg Korobkin, S. Dichiara, B. O'Connor, Ryan Wollaeger, Sylvain Veilleux, T. Sakamoto, Chris Fontes, Chris L. Fryer, Nobuyuki Kawai, Alexander Kutyrev, Chryssa Kouveliotou, E. Troja, Pradip Gatkine, S. B. Cenko, F. E. Marshall, Geoffrey Ryan, E. A. Chase, and Roberto Ricci
- Subjects
Physics ,Line-of-sight ,Stellar population ,010308 nuclear & particles physics ,Star formation ,Extinction (astronomy) ,Astronomy and Astrophysics ,Astrophysics ,Kilonova ,01 natural sciences ,Galaxy ,Space and Planetary Science ,0103 physical sciences ,Gamma-ray burst ,Ejecta ,010303 astronomy & astrophysics - Abstract
We present a detailed multi-wavelength analysis of two short Gamma-Ray Bursts (sGRBs) detected by the Neil Gehrels Swift Observatory: GRB 160624A at $z=0.483$ and GRB 200522A at $z=0.554$. These sGRBs demonstrate very different properties in their observed emission and environment. GRB 160624A is associated to a late-type galaxy with an old stellar population ($\approx$3 Gyr) and moderate on-going star formation ($\approx$1 $M_{\odot}$ yr$^{-1}$). Hubble and Gemini limits on optical/nIR emission from GRB 160624A are among the most stringent for sGRBs, leading to tight constraints on the allowed kilonova properties. In particular, we rule out any kilonova brighter than AT2017gfo, disfavoring large masses of wind ejecta ($\lesssim$0.03 $M_\odot$). In contrast, observations of GRB 200522A uncovered a luminous ($L_\textrm{F125W}\approx 10^{42}$ erg s$^{-1}$ at 2.3~d) and red ($r-H\approx 1.3$ mag) counterpart. The red color can be explained either by bright kilonova emission powered by the radioactive decay of a large amount of wind ejecta (0.03 $M_\odot$ $\lesssim$ $M$ $\lesssim$ 0.1 $M_\odot$) or moderate extinction, $E(B-V)\approx0.1-0.2$ mag, along the line of sight. The location of this sGRB in the inner regions of a young ($\approx$0.1 Gyr) star-forming ($\approx$2-4 $M_{\odot}$ yr$^{-1}$) galaxy and the limited sampling of its counterpart do not allow us to rule out dust effects as contributing, at least in part, to the red color.
- Published
- 2021
10. Swift/UVOT follow-up of Gravitational Wave Alerts in the O3 era
- Author
-
J. P. Osborne, A. Tohuvavohu, A. P. Beardmore, Joshua E. Schlieder, Caryl Gronwall, J. A. Kennea, Scott Barthelmy, E. Ambrosi, Regina Caputo, David Palmer, E. Troja, F. E. Marshall, A. J. Fenney, B. Sbarufatti, M. G. Bernardini, M. de Pasquale, Phil Evans, Sergio Campana, A. Melandri, Valerio D'Elia, S. R. Oates, Peter J. Brown, T. Sakamoto, Paolo Giommi, Hans A. Krimm, Dieter H. Hartmann, M. J. Page, S. Laha, Giancarlo Cusumano, C. Pagani, Antonino D'Ai, N. J. Klingler, G. Tagliaferri, M. Perri, D. Malesani, A. A. Breeveld, J. A. Nousek, S. B. Cenko, P. T. O'Brien, J. L. Racusin, N. P. M. Kuin, K. L. Page, M. H. Siegel, and P. D'Avanzo
- Subjects
Swift ,Physics ,High Energy Astrophysical Phenomena (astro-ph.HE) ,Gravitational-wave observatory ,Active galactic nucleus ,Gravitational wave ,Astrophysics::High Energy Astrophysical Phenomena ,Astrophysics::Instrumentation and Methods for Astrophysics ,Astronomy ,FOS: Physical sciences ,Astronomy and Astrophysics ,Quasar ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Light curve ,Photometry (astronomy) ,gravitational waves ,ultraviolet: general ,Space and Planetary Science ,Gamma-ray burst ,Astrophysics - High Energy Astrophysical Phenomena ,computer ,Astrophysics::Galaxy Astrophysics ,computer.programming_language - Abstract
In this paper, we report on the observational performance of the Swift Ultra-violet/Optical Telescope (UVOT) in response to the Gravitational Wave alerts announced by the Advanced Laser Interferometer Gravitational Wave Observatory and the Advanced Virgo detector during the O3 period. We provide the observational strategy for follow-up of GW alerts and provide an overview of the processing and analysis of candidate optical/UV sources. For the O3 period, we also provide a statistical overview and report on serendipitous sources discovered by Swift/UVOT. Swift followed 18 gravitational-wave candidate alerts, with UVOT observing a total of 424 deg^2. We found 27 sources that changed in magnitude at the 3 sigma level compared with archival u or g-band catalogued values. Swift/UVOT also followed up a further 13 sources reported by other facilities during the O3 period. Using catalogue information, we divided these 40 sources into five initial classifications: 11 candidate active galactic nuclei (AGN)/quasars, 3 Cataclysmic Variables (CVs), 9 supernovae, 11 unidentified sources that had archival photometry and 6 uncatalogued sources for which no archival photometry was available. We have no strong evidence to identify any of these transients as counterparts to the GW events. The 17 unclassified sources are likely a mix of AGN and a class of fast-evolving transient, and one source may be a CV., 25 pages, 6 figures and 5 tables. Submitted to MNRAS. Supplementary contains 23 pages with 8 figures and 1 table
- Published
- 2021
11. AN INTRINSIC CORRELATION BETWEEN GRB OPTICAL/UV AFTERGLOW BRIGHTNESS AND DECAY RATE
- Author
-
S. R. Oates, M. J. Page, M. De Pasquale, P. Schady, A. A. Breeveld, S. T. Holland, N. P. M. Kuin, and F. E. Marshall
- Published
- 2020
12. Short gamma-ray bursts within 200 Mpc
- Author
-
B. O’Connor, Paz Beniamini, E. Troja, T. Sakamoto, J. K. Cannizzo, F. E. Marshall, S. Dichiara, and A. Y. Lien
- Subjects
High Energy Astrophysical Phenomena (astro-ph.HE) ,Physics ,media_common.quotation_subject ,Astrophysics::High Energy Astrophysical Phenomena ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Kilonova ,Galaxy ,Universe ,Neutron star ,Space and Planetary Science ,Observatory ,Astrophysics - High Energy Astrophysical Phenomena ,Ejecta ,Gamma-ray burst ,Astrophysics::Galaxy Astrophysics ,media_common ,Fermi Gamma-ray Space Telescope - Abstract
We present a systematic search for short-duration gamma-ray bursts (GRBs) in the local Universe based on 14 years of observations with the Neil Gehrels Swift Observatory. We cross-correlate the GRB positions with the GLADE catalogue of nearby galaxies, and find no event at a distance $\lesssim$100 Mpc and four plausible candidates in the range 100 Mpc$\lesssim$$D$$\lesssim$200 Mpc. Although affected by low statistics, this number is higher than the one expected for chance alignments to random galaxies, and possibly suggests a physical association between these bursts and nearby galaxies. By assuming a local origin, we use these events to constrain the range of properties for X-ray counterparts of neutron star mergers. Optical upper limits place tight constraints on the onset of a blue kilonova, and imply either low masses ($\lesssim10^{-3}\,M_{\odot}$) of lanthanide-poor ejecta or unfavorable orientations ($\theta_{obs}\gtrsim$30 deg). Finally, we derive that the all-sky rate of detectable short GRBs within 200 Mpc is $1.3^{+1.7}_{-0.8}$ yr$^{-1}$ (68\% confidence interval), and discuss the implications for the GRB outflow structure. If these candidates are instead of cosmological origin, we set a upper limit of $\lesssim$2.0 yr$^{-1}$ (90\% confidence interval) to the rate of nearby events detectable with operating gamma-ray observatories, such as Swift and Fermi., Comment: 13 pages, 9 figures, 1 table, accepted for publication in MNRAS
- Published
- 2020
13. A study of gamma-ray burst afterglows as they first come into view of the Swift Ultraviolet and Optical Telescope
- Author
-
S. W. K. Emery, S. R. Oates, P. W. A. Roming, M. de Pasquale, F. E. Marshall, M. J. Page, N. P. M. Kuin, M. H. Siegel, and A. A. Breeveld
- Subjects
Physics ,High Energy Astrophysical Phenomena (astro-ph.HE) ,Swift Gamma-Ray Burst Mission ,Astrophysics::High Energy Astrophysical Phenomena ,Astrophysics::Instrumentation and Methods for Astrophysics ,FOS: Physical sciences ,Astronomy and Astrophysics ,Field of view ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Optical telescope ,Photometry (optics) ,Stars ,Space and Planetary Science ,Observatory ,Gamma-ray burst ,Astrophysics - High Energy Astrophysical Phenomena - Abstract
We examine the the emission from optically bright gamma-ray burst (GRB) afterglows as the Ultraviolet and Optical Telescope (UVOT) on the Neil Gehrels Swift Observatory first begins observing, following the slew to target the GRB, while the pointing of the Swift satellite is still settling. We verify the photometric quality of the UVOT settling data using bright stars in the field of view. In the majority of cases we find no problems with the settling exposure photometry, but in one case we excise the first second of the exposure to mitigate a spacecraft attitude reconstruction issue, and in a second case we exclude the first second of the exposure in which the UVOT photocathode voltage appears to be ramping up. Of a sample of 23 afterglows which have peak V magnitudes 0.5 mag in their optical lightcurves, and there is a marginal trend for these GRBs to have long T90. Such a trend is expected for thick-shell afterglows, but the temporal indices of the optical rises and the timing of the optical peaks appear to rule out thick shells., accepted for publication in MNRAS
- Published
- 2019
- Full Text
- View/download PDF
14. Erratum: Swift follow-up of gravitational wave triggers: results from the first aLIGO run and optimisation for the future
- Author
-
J. A. Kennea, M. H. Siegel, E. Troja, K. L. Page, M. Perri, Maciej Bilicki, A. Y. Lien, Sergio Campana, N. Gehrels, P. A. Evans, Gianpiero Tagliaferri, J. P. Osborne, David Palmer, F. E. Marshall, V. D'Elia, P. T. O'Brien, Scott Barthelmy, S. B. Cenko, Nial R. Tanvir, B. Sbarufatti, and D. N. Burrows
- Subjects
Swift ,Physics ,Space and Planetary Science ,Gravitational wave ,Astronomy ,Astronomy and Astrophysics ,computer ,computer.programming_language - Abstract
This is a correction to: Monthly Notices of the Royal Astronomical Society, Volume 462, Issue 2, 21 October 2016, Pages 1591–1602, https://doi.org/10.1093/mnras/stw1746
- Published
- 2019
15. Significant and variable linear polarization during the prompt optical flash of GRB 160625B
- Author
-
N. M. Budnev, Eleonora Troja, R. Rebolo Lopez, V. G. Kornilov, Miquel Serra-Ricart, Vicki Toy, Carole Mundell, Alexander Kutyrev, Michael G. Richer, William H. Lee, Roberto Ricci, V. M. Lipunov, Assaf Horesh, Enrico Ramirez-Ruiz, V. Yurkov, Alan M. Watson, David A. H. Buckley, Jason X. Prochaska, S. B. Cenko, Nathaniel R. Butler, N. V. Tyurina, M. H. Wieringa, N. Gehrels, A. S. Fruchter, F. E. Marshall, Mikhail Panasyuk, O. A. Gress, Shiho Kobayashi, Carlos Román-Zúñiga, E. S. Gorbovskoy, and J. Gonzalez
- Subjects
Physics ,Multidisciplinary ,Stellar mass ,010308 nuclear & particles physics ,Linear polarization ,Astrophysics::High Energy Astrophysical Phenomena ,Synchrotron radiation ,Astronomy ,Astrophysics ,Polarization (waves) ,01 natural sciences ,Magnetic field ,Afterglow ,Black hole ,0103 physical sciences ,Gamma-ray burst ,010303 astronomy & astrophysics ,QC ,QB - Abstract
Newly formed black holes of stellar mass launch collimated outflows (jets) of ionized matter that approach the speed of light. These outflows power prompt, brief and intense flashes of γ-rays known as γ-ray bursts (GRBs), followed by longer-lived afterglow radiation that is detected across the electromagnetic spectrum. Measuring the polarization of the observed GRB radiation provides a direct probe of the magnetic fields in the collimated jets. Rapid-response polarimetric observations of newly discovered bursts have probed the initial afterglow phase1, 2, 3, and show that, minutes after the prompt emission has ended, the degree of linear polarization can be as high as 30 per cent—consistent with the idea that a stable, globally ordered magnetic field permeates the jet at large distances from the central source3. By contrast, optical4, 5, 6 and γ-ray7, 8, 9 observations during the prompt phase have led to discordant and often controversial10, 11, 12 results, and no definitive conclusions have been reached regarding the origin of the prompt radiation or the configuration of the magnetic field. Here we report the detection of substantial (8.3 ± 0.8 per cent from our most conservative simulation), variable linear polarization of a prompt optical flash that accompanied the extremely energetic and long-lived prompt γ-ray emission from GRB 160625B. Our measurements probe the structure of the magnetic field at an early stage of the jet, closer to its central black hole, and show that the prompt phase is produced via fast-cooling synchrotron radiation in a large-scale magnetic field that is advected from the black hole and distorted by dissipation processes within the jet.
- Published
- 2017
16. The First Ultraviolet Detection of the Large Magellanic Cloud Pulsar PSR B0540–69 and Its Multi-wavelength Properties
- Author
-
Christian Gouiffes, F. E. Marshall, Luca Zampieri, Gottfried Kanbach, Andrew Shearer, Giampiero Naletto, David A. Smith, Cesare Barbieri, L. Guillemot, A. De Luca, Roberto Mignani, B. Rudak, Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Centre National d’Études Spatiales [Paris] (CNES), Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), Université Sciences et Technologies - Bordeaux 1-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), 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), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), 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), PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES)
- Subjects
010504 meteorology & atmospheric sciences ,Astrophysics::High Energy Astrophysical Phenomena ,FOS: Physical sciences ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Vela ,01 natural sciences ,Pulsar ,pulsars: general ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,Space Telescope Imaging Spectrograph ,0105 earth and related environmental sciences ,High Energy Astrophysical Phenomena (astro-ph.HE) ,Physics ,Spectral index ,Nebula ,[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph] ,Crab Pulsar ,pulsars: individual (PSR B0540-69) ,Image (category theory) ,Astrophysics::Instrumentation and Methods for Astrophysics ,Astronomy and Astrophysics ,Light curve ,pulsars: individual ,[SDU]Sciences of the Universe [physics] ,13. Climate action ,Space and Planetary Science ,(PSR B0540–69) ,Astrophysics - High Energy Astrophysical Phenomena ,[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] - Abstract
We observed the young ($\sim 1700$ yrs) pulsar PSR B0540-69 in the near-ultraviolet (UV) for the first time with the Space Telescope Imaging Spectrograph (STIS) aboard the {\em Hubble Space Telescope}. Imaging observations with the NUV- and FUV-MAMA detectors in TIME-TAG mode allowed us to clearly detect the pulsar in two bands around 2350\AA\ and 1590\AA, with magnitudes $m_{\rm NUV} =21.449 \pm 0.019$ and $m_{\rm FUV} =21.832 \pm 0.103$. We also detected the pulsar-wind nebula (PWN) in the NUV-MAMA image, with a morphology similar to that observed in the optical and near-infrared (IR). The extinction-corrected NUV and FUV pulsar fluxes are compatible with a very steep power law spectrum $F_{\nu} \propto \nu^{-\alpha}$ with spectral index $\alpha_{\rm UV} \sim 3$, non compatible with a Rayleigh Jeans spectrum, indicating a non-thermal origin of the emission. The comparison with the optical/near-IR power-law spectrum (spectral index $\alpha_{\rm O,nIR} \sim 0.7$), indicates an abrupt turn-off at wavelengths below 2500 \AA, not observed in other pulsars. We detected pulsations in both the NUV and FUV data at the 50 ms pulsar period. In both cases, the pulse profile features two peaks closely spaced in phase, as observed in the optical and X-ray light curves. The NUV/FUV peaks are also aligned in phase with those observed in the radio (1.4 GHz), optical, X, and $\gamma$-ray light curves, like in the Crab pulsar, implying a similar beaming geometry across all wavelengths. PSR B0540-69 is now the fifth isolated pulsar, together with Crab, Vela, PSR\, B0656+14, and the radio-quiet Geminga, detected in the optical, near-UV, near-IR, X-rays and $\gamma$-rays, and seen to pulsate in at least four of these energy bands., Comment: 33 pages, 6 figures, accepted for publication on ApJ
- Published
- 2019
17. The use and calibration of read-out streaks to increase the dynamic range of the Swift Ultraviolet/Optical Telescope
- Author
-
M. H. Siegel, Vladimir Yershov, N. P. M. Kuin, A. P. Beardmore, S. T. Holland, P. W. A. Roming, M. Carter, Philip J. Smith, M. de Pasquale, A. A. Breeveld, B. Hancock, M. Symeonidis, M. J. Page, F. E. Marshall, and S. R. Oates
- Subjects
Physics ,Photon ,business.industry ,Dynamic range ,Streak ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Optical telescope ,Photon counting ,Photometry (optics) ,Stars ,Optics ,Space and Planetary Science ,Ultraviolet astronomy ,Astrophysics - Instrumentation and Methods for Astrophysics ,business ,Instrumentation and Methods for Astrophysics (astro-ph.IM) - Abstract
The dynamic range of photon counting micro-channel-plate (MCP) intensified charged-coupled device (CCD) instruments such as the Swift Ultraviolet/Optical Telescope (UVOT) and the XMM-Newton Optical Monitor (XMM-OM) is limited at the bright end by coincidence loss, the superposition of multiple photons in the individual frames recorded by the CCD. Photons which arrive during the brief period in which the image frame is transferred for read out of the CCD are displaced in the transfer direction in the recorded images. For sufficiently bright sources, these displaced counts form read-out streaks. Using UVOT observations of Tycho-2 stars, we investigate the use of these read-out streaks to obtain photometry for sources which are too bright (and hence have too much coincidence loss) for normal aperture photometry to be reliable. For read-out-streak photometry, the bright-source limiting factor is coincidence loss within the MCPs rather than the CCD. We find that photometric measurements can be obtained for stars up to 2.4 magnitudes brighter than the usual full-frame coincidence-loss limit by using the read-out streaks. The resulting bright-limit Vega magnitudes in the UVOT passbands are UVW2=8.80, UVM2=8.27, UVW1=8.86, u=9.76, b=10.53, v=9.31 and White=11.71; these limits are independent of the windowing mode of the camera. We find that a photometric precision of 0.1 mag can be achieved through read-out streak measurements. A suitable method for the measurement of read-out streaks is described and all necessary calibration factors are given., 11 pages, accepted for publication in MNRAS. Code available from the calibration link at http://www.mssl.ucl.ac.uk/www_astro/uvot
- Published
- 2013
18. An intrinsic correlation between GRB optical/UV afterglow brightness and decay rate
- Author
-
A. A. Breeveld, M. de Pasquale, S. T. Holland, Patricia Schady, N. P. M. Kuin, Mat Page, F. E. Marshall, and S. R. Oates
- Subjects
Physics ,Brightness ,Space and Planetary Science ,General Engineering ,Astronomy and Astrophysics ,Outflow ,Astrophysics ,Viewing angle ,Gamma-ray burst ,Light curve ,Spearman's rank correlation coefficient ,Afterglow ,Luminosity - Abstract
We examine a sample of 47 Swift/UVOT long Gamma-ray Burst light curves. Using the restframe light curves we find a correlation between the logarith mic luminosity determined at 200s, log L200s, and average decay rate measured from 200s onwards, α>200s. The Spearman rank coefficient for the correlation is -0.54 at a probability of 99.99 % (3.9σ ). We find the log L 200s α>200s correlation to be an intrinsic property of long GRBs and discuss three potential causes. Of these three scenarios, we are able to exclude the correlation as re sulting naturally from the standard afterglow model. However, we cannot presently exclude or distinguish between the other two possibilities. The first scenario is that there is some prope rty of the central engine, outflow or external medium that affects the rate of energy release in such a way that the bright afterglows release their energy more quickly than the fainter afterglows. Alternatively the correlation may be produced by variation of the observers viewing angle, with observers at large viewing angles observing fainter and slower light curves.
- Published
- 2013
19. Swift follow-up of gravitational wave triggers: results from the first aLIGO run and optimization for the future
- Author
-
Nial R. Tanvir, M. Perri, Maciej Bilicki, Sergio Campana, B. Sbarufatti, Scott Barthelmy, Eleonora Troja, David N. Burrows, G. Tagliaferri, J. A. Kennea, Phil Evans, K. L. Page, A. Y. Lien, F. E. Marshall, S. B. Cenko, J. P. Osborne, N. Gehrels, David Palmer, Valerio D'Elia, M. H. Siegel, P. T. O'Brien, ITA, USA, GBR, NLD, and POL
- Subjects
Swift ,Data products ,FOS: Physical sciences ,Library science ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,Infrared Processing and Analysis Center ,Observatory ,0103 physical sciences ,Analysis software ,010306 general physics ,Instrumentation and Methods for Astrophysics (astro-ph.IM) ,010303 astronomy & astrophysics ,computer.programming_language ,High Energy Astrophysical Phenomena (astro-ph.HE) ,Physics ,business.industry ,HEALPix ,European research ,Astronomy ,Astronomy and Astrophysics ,Space and Planetary Science ,Data center ,Astrophysics - High Energy Astrophysical Phenomena ,Astrophysics - Instrumentation and Methods for Astrophysics ,business ,computer - Abstract
During its first observing run, in late 2015, the advanced LIGO facility announced 3 gravitational wave (GW) triggers to electromagnetic follow-up partners. Two of these have since been confirmed as being of astrophysical origin: both are binary black hole mergers at ~500 Mpc; the other trigger was later found not to be astrophysical. In this paper we report on the Swift follow up observations of the second and third triggers, including details of 21 X-ray sources detected; none of which can be associated with the GW event. We also consider the challenges that the next GW observing run will bring as the sensitivity and hence typical distance of GW events will increase. We discuss how to effectively use galaxy catalogues to prioritise areas for follow up, especially in the presence of distance estimates from the GW data. We also consider two galaxy catalogues and suggest that the high completeness at larger distances of the 2MASS Photometric Redshift Catalogue (2MPZ) makes it very well suited to optimise Swift follow-up observations., Comment: Modified 2018 December, to correct a normalisation error in equation (7). Corresponding erratum has been submitted to MNRAS
- Published
- 2016
20. A new , low braking index for the LMC PULSAR B0540-69
- Author
-
Alice K. Harding, David Stanley Smith, F. E. Marshall, Pierre Martin, L. Guillemot, GSFC Astrophysics Science Division, NASA Goddard Space Flight Center (GSFC), Unité Scientifique de la Station de Nançay (USN), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National d’Études Spatiales [Paris] (CNES), Département SHS, Centre National de la Recherche Scientifique (CNRS), Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), and Université Sciences et Technologies - Bordeaux 1-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
Physics ,High Energy Astrophysical Phenomena (astro-ph.HE) ,Swift Gamma-Ray Burst Mission ,Index (economics) ,pulsars: individual (PSR B0540–69) ,[SDU.ASTR.CO]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO] ,[SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR] ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Ephemeris ,01 natural sciences ,Pulsar ,Space and Planetary Science ,0103 physical sciences ,Astrophysics - High Energy Astrophysical Phenomena ,010306 general physics ,Large Magellanic Cloud ,010303 astronomy & astrophysics ,Noise (radio) - Abstract
We report the results of a 16-month monitoring campaign using the Swift satellite of PSR B0540-69, a young pulsar in the Large Magellanic Cloud. Phase connection was maintained throughout the campaign so that a reliable ephemeris could be determined, and the length of the campaign is adequate to accurately determine the spin frequency and its first and second derivatives. The braking index is 0.031 +/- 0.013 (90% confidence), a value much lower than previously reported for B0540-69 and almost all other young pulsars. We use data from the extensive monitoring campaign with RXTE to show that timing noise is unlikely to significantly affect the measurement. This is the first measurement of the braking index in the pulsar's recently discovered high spin-down state. We discuss possible mechanisms for producing the low braking index., Comment: 6 pages, 1 figure accepted for publication in ApJ Letters
- Published
- 2016
21. A correlation between the intrinsic brightness and average decay rate ofSwift/UVOT gamma-ray burst optical/ultraviolet light curves
- Author
-
Stephen T. Holland, M. J. Page, M. de Pasquale, A. A. Breeveld, S. R. Oates, F. E. Marshall, N. P. M. Kuin, and Patricia Schady
- Subjects
Physics ,Astrophysics::High Energy Astrophysical Phenomena ,Sigma ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Light curve ,Viewing angle ,Spearman's rank correlation coefficient ,Luminosity ,Intrinsic brightness ,Space and Planetary Science ,Outflow ,Gamma-ray burst - Abstract
We examine a sample of 48 Swift/UVOT long Gamma-ray Burst light curves and find a correlation between the logarithmic luminosity at 200s and average decay rate determined from 200s onwards, with a Spearman rank coefficient of -0.58 at a significance of 99.998% (4.2 sigma ). We discuss the causes of the log L200s - alpha (greater than) 200s correlation, finding it to be an intrinsic property of long GRBs, and not resulting from the selection criteria. We find two ways to produce the correlation. One possibility is that there is some property of the central engine, outflow or external medium that affects the rate of energy release so that the bright afterglows release their energy more quickly and decay faster than the fainter afterglows. Alternatively, the correlation may be produced by variation of the observers viewing angle, with observers at large viewing angles observing fainter and slower decaying light curves.
- Published
- 2012
22. ULTRAVIOLET NUMBER COUNTS OF GALAXIES FROMSWIFTULTRAVIOLET/OPTICAL TELESCOPE DEEP IMAGING OF THE CHANDRA DEEP FIELD SOUTH
- Author
-
Caryl Gronwall, F. E. Marshall, D. Hinshaw, P. W. A. Roming, Martin Still, P. A. Curran, T. S. Koch, E. A. Hoversten, D. E. vanden Berk, A. A. Breeveld, and M. H. Siegel
- Subjects
Physics ,Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,Star formation ,Astrophysics::High Energy Astrophysical Phenomena ,Astrophysics::Instrumentation and Methods for Astrophysics ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Optical telescope ,Galaxy ,Luminosity ,Space and Planetary Science ,Galaxy formation and evolution ,Chandra Deep Field South ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Galaxy Astrophysics ,Space Telescope Imaging Spectrograph ,Astrophysics - Cosmology and Nongalactic Astrophysics ,Luminosity function (astronomy) - Abstract
Deep Swift UV/Optical Telescope (UVOT) imaging of the Chandra Deep Field South is used to measure galaxy number counts in three near ultraviolet (NUV) filters (uvw2: 1928 A, uvm2: 2246 A, uvw1: 2600 A) and the u band (3645 A). UVOT observations cover the break in the slope of the NUV number counts with greater precision than the number counts by the Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) and the Galaxy Evolution Explorer (GALEX), spanning a range from 21 < m_AB < 25. Number counts models confirm earlier investigations in favoring models with an evolving galaxy luminosity function., 20 pages, 6 figures, accepted to ApJ
- Published
- 2009
23. GRB 081203A:SwiftUVOT captures the earliest ultraviolet spectrum of a gamma-ray burst
- Author
-
Martin Still, S. T. Holland, C. Gronwall, M. J. Page, F. E. Marshall, M. Carter, C. W. James, Peter Brown, E. A. Hoversten, A. A. Breeveld, Philip J. Smith, W. B. Landsman, A. Cucciara, Patricia Schady, A. M. Parsons, S. R. Oates, N. P. M. Kuin, P. W. A. Roming, M. de Pasquale, D. M. Palmer, H. Lamoureux, P. A. Curran, T. Kennedy, S. D. Hunsberger, and S. Koch
- Subjects
Physics ,Swift ,Brightness ,Astronomy and Astrophysics ,Astrophysics ,medicine.disease_cause ,Redshift ,Galaxy ,Grism ,Space and Planetary Science ,medicine ,Gamma-ray burst ,computer ,Ultraviolet ,computer.programming_language - Abstract
We present the earliest ever ultraviolet spectrum of a gamma-ray burst (GRB) as observed with the Swift-UVOT. The GRB 081203A spectrum was observed for 50 seconds with the UV grism starting 251 seconds after the Swift-BAT trigger when the GRB was of u ~13.4 mag and still rising to its peak optical brightness. The UV grism spectrum shows a damped Ly-alpha line, Ly-beta, and the Lyman continuum break at a redshift z = 2.05 +/- 0.01. A model fit to the Lyman absorption implies log N(HI) = 22.0 +/- 0.2 cm-2, which is typical for GRB host galaxies with damped Ly-alpha absorbers. This observation of GRB 081203A demonstrates that for GRBs brighter than v ~14 mag and with 0.5 < z < 3.5 the UVOT will be able to provide redshifts, and probe for damped Ly-alpha absorbers within 4-6 minutes from the time of the Swift-BAT trigger.
- Published
- 2009
24. ROSSI X-RAY TIMING EXPLORERANDBeppoSAXOBSERVATIONS OF THE TRANSIENT X-RAY PULSAR XTE J1859+083
- Author
-
J. J. M. in 't Zand, A. M. Levine, R. H. D. Corbet, and F. E. Marshall
- Subjects
Physics ,Neutron star ,Pulsar ,Accretion (meteorology) ,Space and Planetary Science ,Be star ,Astrophysics::High Energy Astrophysical Phenomena ,Orbital motion ,X-ray binary ,Astronomy and Astrophysics ,Astrophysics ,Orbital period ,X-ray pulsar - Abstract
We present observations of the 9.8 s X-ray pulsar XTE J1859+083 made with the All Sky Monitor (ASM) and Proportional Counter Array (PCA) on board the Rossi X-ray Timing Explorer, and the Wide Field Camera (WFC) on board BeppoSAX. The ASM data cover a 12 year time interval and show that an extended outburst occurred between approximately MJD 50,250 and 50,460 (1996 June 16 to 1997 January 12). The ASM data excluding this outburst interval suggest a possible modulation with a period of 60.65 ± 0.08 days. Eighteen sets of PCA observations were obtained over an approximately one month interval in 1999. The flux variability measured with the PCA appears consistent with the possible period found with the ASM. The PCA measurements of the pulse period showed it to decrease nonmonotonically and then to increase significantly. Doppler shifts due to orbital motion rather than accretion torques appear to be better able to explain the pulse period changes. Observations with the WFC during the extended outburst give a position that is consistent with a previously determined PCA error box, but which has a significantly smaller error. The transient nature of XTE J1859+083 and the length of its pulse period are consistent with it being a Be/neutron star binary. The possible 60.65 day orbital period would be of the expected length for a Be star system with a 9.8 s pulse period.
- Published
- 2009
25. Properties of X-ray binaries in the Magellanic Clouds from RXTE and Chandra observations
- Author
-
Jose Luis Galache, K. E. McGowan, R. H. D. Corbet, L. J. Townsend, F. E. Marshall, M. P. E. Schurch, and M. J. Coe
- Subjects
Physics ,education.field_of_study ,Astrophysics::High Energy Astrophysical Phenomena ,Milky Way ,Astrophysics (astro-ph) ,Population ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Light curve ,Accretion (astrophysics) ,Galaxy ,Neutron star ,Stars ,Pulsar ,Space and Planetary Science ,education ,Astrophysics::Galaxy Astrophysics - Abstract
The X-ray binary population of the SMC is very different from that of the Milky Way consisting, with one exception, entirely of transient pulsating Be/neutron star binaries. We have now been monitoring these SMC X-ray pulsars for over 10 years using the Rossi X-ray Timing Explorer with observations typically every week. The RXTE observations have been complemented with surveys made using the Chandra observatory. The RXTE observations are non-imaging but enable detailed studies of pulsing sources. In contrast, Chandra observations can provide precise source locations and detections of sources at lower flux levels, but do not provide the same timing information or the extended duration light curves that RXTE observations do. We summarize the results of these monitoring programs which provide insights into both the differences between the SMC and the Milky Way, and the details of the accretion processes in X-ray pulsars., To appear in proceedings of IAU Symposium 256, The Magellanic System: Stars, Gas, and Galaxies
- Published
- 2008
26. GRB 060607A: a gamma-ray burst with bright asynchronous early X-ray and optical emissions
- Author
-
Neil Gehrels, Stephen T. Holland, Craig B. Markwardt, Patricia T. Boyd, Jay Cummings, Samantha Oates, M. R. Goad, Peter Mészáros, K. L. Page, F. E. Marshall, and Houri Ziaeepour
- Subjects
Physics ,Infrared ,Astrophysics::High Energy Astrophysical Phenomena ,Gamma ray ,Astronomy ,Astronomy and Astrophysics ,Fermi acceleration ,Astrophysics ,Light curve ,Redshift ,law.invention ,Space and Planetary Science ,law ,Light emission ,Gamma-ray burst ,Flare - Abstract
The early optical emission of the moderately high redshift (2 = 3.08) GRB 060607A shows a remarkable broad and strong peak with a rapid rise and a relatively slow power-law decay. It is not coincident with the strong early-time flares seen in the X-ray and gamma-ray energy bands. There is weak evidence for variability superposed on this dominant component in several optical bands that can be related to flares in high-energy bands. While for a small number of gamma-ray bursts (GRBs), well-sampled optical flares have been observed simultaneously with X-ray and gamma-ray pulses, GRB 060607A is one of the few cases where the early optical emission shows no significant evidence for correlation with the prompt emission. In this work we first report in detail the broad-band observations of this burst by Swift. Then by applying a simple model for the dynamics and the synchrotron radiation of a relativistic shock, we show that the dominant component of the early emissions in optical wavelengths has the same origin as the tail emission produced after the main gamma-ray activity. The most plausible explanation for the peak in the optical light curve seems to be the cooling of the prompt after the main collisions, shifting the characteristic synchrotron frequency to the optical bands. The fact that the early emission in X-ray does not show a steep decay, like what is observed in many other GRBs, is further evidence for slow cooling of the prompt shell within this GRB. It seems that the cooling process requires a steepening of the electron energy distribution and/or a break in this distribution at high energies. From simultaneous gamma-ray emission during the first flare, the behaviour of hardness ratio, and the lack of spectral features, we conclude that the X-ray flares are due to the collision of late shells rather than late reprocessing of the central engine activities. The sharp break in the X-ray light curve at few thousands of seconds after the trigger, is not observed in the infrared/optical/ultraviolet bands, and therefore cannot be a jet break. Either the X-ray break is due to a change in the spectrum of the accelerated electrons or the lack of an optical break is due to the presence of a related delayed response component.
- Published
- 2008
27. Swift – The First 100 Gamma-Ray Bursts
- Author
-
F. E. Marshall
- Subjects
Swift ,Physics ,Nuclear and High Energy Physics ,Astrophysics::High Energy Astrophysical Phenomena ,Astrophysics::Instrumentation and Methods for Astrophysics ,Astronomy ,Astrophysics ,Atomic and Molecular Physics, and Optics ,Optical telescope ,Redshift ,Observatory ,Gamma-ray burst ,computer ,computer.programming_language - Abstract
Gamma Ray Bursts are the largest explosions in the Universe, and the recently launched Swift mission is a multi-wavelength observatory that has greatly expanded our ability to study them. Swift's wide-field gamma-ray camera is detecting about 100 bursts per year that are quickly viewed with sensitive X-ray and UV/optical telescopes on the observatory. Positions are rapidly released to the world to enable ground-based observations. Results from the first year of observations will be presented. The mystery of short GRBs has been solved, very high redshift bursts discovered, and enormous X-ray flares found in afterglows.
- Published
- 2007
28. The Swift gamma-ray burst GRB 050422
- Author
-
A. P. Beardmore, Bing Zhang, Shiho Kobayashi, V. La Parola, F. E. Marshall, David N. Burrows, M. Capalbi, J. P. Osborne, P. T. O'Brien, M. R. Goad, Olivier Godet, Joanne E. Hill, K. L. Page, and Alan A. Wells
- Subjects
Physics ,Swift ,Spectral index ,Astrophysics::High Energy Astrophysical Phenomena ,Soft X-radiation ,Astronomy ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Light curve ,Power law ,Afterglow ,Space and Planetary Science ,Gamma-ray burst ,X ray spectra ,computer ,computer.programming_language - Abstract
We describe observations of GRB 050422, a Swift-discovered gamma-ray burst. The prompt gamma-ray emission had a T90 duration of 59 s and was multipeaked, with the main peak occurring at T + 53 s. Swift was able to follow the X-ray afterglow within 100 s of the burst trigger. The X-ray light curve, which shows a steep early decline, can be described by a broken power law with an initial decay slope of α1 ∼ 5.0, a break time tb ∼ 270 s and a post-break decay slope of α2 ∼ 0.9, when the zero time of the X-ray emission is taken to be the burst trigger time. However, if the zero time is shifted to coincide with the onset of main peak in the gamma-ray light curve then the initial decay slope is shallower with α1 ∼ 3.2. The initial gamma-ray spectrum can be modelled by a power law with a spectral index of β B = 0.50 ± 0.19. However, the early time X-ray spectrum is significantly steeper than this and requires a spectral index of βX = 2.33 +0.58 −0.55. In comparison with other Swift bursts, GRB 050422 was unusually X-ray faint, had a soft X-ray spectrum, and had an unusually steep early X-ray decline. Even so, its behaviour can be accommodated by standard models. The combined BAT/XRT light curve indicates that the initial, steeply declining, X-ray emission is related to the tail of the prompt gamma-ray emission. The shallower decay seen after the break is consistent with the standard afterglow model.
- Published
- 2007
29. ISS-Lobster: a low-cost wide-field x-ray transient detector on the ISS
- Author
-
Robert Petre, F. E. Marshall, Andy Ptak, Neil Gehrels, Jordan Camp, Scott Barthelmy, and Judith Racusin
- Subjects
Physics ,Neutron star ,Supernova ,Supermassive black hole ,X-ray transient ,Stellar mass ,Gravitational wave ,Astrophysics::High Energy Astrophysical Phenomena ,Target of opportunity ,Astronomy ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Redshift - Abstract
ISS-Lobster is a wide-field X-ray transient detector proposed to be deployed on the International Space Station. Through its unique imaging X-ray optics that allow a 30 deg by 30 deg FoV, a 1 arc min position resolution and a 1.6x10-11 erg/(sec cm2) sensitivity in 2000 sec, ISS-Lobster will observe numerous events per year of X-ray transients related to compact objects, including: tidal disruptions of stars by supermassive black holes, supernova shock breakouts, neutron star bursts and superbursts, high redshift Gamma-Ray Bursts, and perhaps most exciting, X-ray counterparts of gravitational wave detections involving stellar mass and possibly supermassive black holes. The mission includes a 3-axis gimbal system that allows fast Target of Opportunity pointing, and a small gamma-ray burst monitor. In this article we focus on ISS-Lobster measurements of X-ray counterparts of detections by the world-wide ground-based gravitational wave network.
- Published
- 2015
30. Happy Birthday Swift: Ultra-long GRB141121A and its broad-band Afterglow
- Author
-
Maryam Modjaz, Antonino Cucchiara, C. R. Klein, Jason X. Prochaska, J. A. de Diego, J. Jesús González, Carlos Román-Zúñiga, Michael G. Richer, Eleonora Troja, Ori D. Fox, C. Pagani, William H. Lee, John Capone, F. E. Marshall, Assaf Horesh, Péter Veres, Alexander Kutyrev, S. B. Cenko, Josh Bloom, Alan M. Watson, A. Y. Lien, Enrico Ramirez-Ruiz, Dale A. Frail, Vicki Toy, Nathaniel R. Butler, Daniel A. Perley, L. Georgiev, H. Moseley, Alessandra Corsi, O. M. Littlejohns, and N. Gehrels
- Subjects
Swift ,Physics ,High Energy Astrophysical Phenomena (astro-ph.HE) ,010504 meteorology & atmospheric sciences ,FOS: Physical sciences ,Astronomy and Astrophysics ,Context (language use) ,Astrophysics ,Light curve ,01 natural sciences ,Redshift ,Afterglow ,Space and Planetary Science ,0103 physical sciences ,Broadband ,QD ,Gamma-ray burst ,Astrophysics - High Energy Astrophysical Phenomena ,010303 astronomy & astrophysics ,computer ,Isotropic energy ,QC ,0105 earth and related environmental sciences ,computer.programming_language ,QB - Abstract
We present our extensive observational campaign on the Swift-discovered GRB141121A, al- most ten years after its launch. Our observations covers radio through X-rays, and extends for more than 30 days after discovery. The prompt phase of GRB 141121A lasted 1410 s and, at the derived redshift of z = 1.469, the isotropic energy is E{\gamma},iso = 8.0x10^52 erg. Due to the long prompt duration, GRB141121A falls into the recently discovered class of UL-GRBs. Peculiar features of this burst are a flat early-time optical light curve and a radio-to-X-ray rebrightening around 3 days after the burst. The latter is followed by a steep optical-to-X-ray decay and a much shallower radio fading. We analyze GRB 141121A in the context of the standard forward-reverse shock (FS,RS) scenario and we disentangle the FS and RS contributions. Finally, we comment on the puzzling early-time (t ~3 d) behavior of GRB 141121A, and suggest that its interpretation may require a two-component jet model. Overall, our analysis confirms that the class of UL-GRBs represents our best opportunity to firmly establish the prominent emission mechanisms in action during powerful GRB explosions, and future missions (like SVOM, XTiDE, or ISS-Lobster) will provide many more of such objects., Comment: 25 pages, 5 pages, accepted for publication on The Astrophysical Journal (June 2015)
- Published
- 2015
- Full Text
- View/download PDF
31. Discovery of a Spin-Down State Change in the LMC Pulsar B0540-69
- Author
-
Lucas Guillemot, Pierrick Martin, F. E. Marshall, Alice K. Harding, David Smith, GSFC Astrophysics Science Division, NASA Goddard Space Flight Center (GSFC), Unité Scientifique de la Station de Nançay (USN), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), 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 d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), Université Sciences et Technologies - Bordeaux 1-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), 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), and Université Sciences et Technologies - Bordeaux 1 (UB)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
Physics ,High Energy Astrophysical Phenomena (astro-ph.HE) ,[SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR] ,Astrophysics::High Energy Astrophysical Phenomena ,Spin rate ,Magnetosphere ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Pulsar ,13. Climate action ,Space and Planetary Science ,Astrophysics - High Energy Astrophysical Phenomena ,Large Magellanic Cloud ,Spin-½ - Abstract
We report the discovery of a large, sudden, and persistent increase in the spin-down rate of B0540-69, a young pulsar in the Large Magellanic Cloud, using observations from the Swift and RXTE satellites. The relative increase in the spin-down rate of 36% is unprecedented for B0540-69. No accompanying change in the spin rate is seen, and no change is seen in the pulsed X-ray emission from B0540-69 following the change in the spin-down rate. Such large relative changes in the spin-down rate are seen in the recently discovered class of 'intermittent pulsars', and we compare the properties of B0540-69 to such pulsars. We consider possible changes in the magnetosphere of the pulsar that could cause such a large change in the spin-down rate., Comment: 6 pages, 2 figures, accepted for publication in ApJ Letters
- Published
- 2015
- Full Text
- View/download PDF
32. Calibration of the Swift-UVOT ultraviolet and visible grisms
- Author
-
H. Lamoureux, W. B. Landsman, A. A. Breeveld, K. O. Mason, C. James, P. W. A. Roming, M. H. Siegel, Peter J. Brown, Vladimir Yershov, M. de Pasquale, Philip J. Smith, M. J. Page, S. R. Oates, N. P. M. Kuin, M. Mehdipour, M. Carter, Martin Still, T. Kennedy, and F. E. Marshall
- Subjects
Physics ,business.industry ,Detector ,Antenna aperture ,Flux ,Astronomy and Astrophysics ,medicine.disease_cause ,Grism ,Wavelength ,Optics ,Space and Planetary Science ,medicine ,Calibration ,Spectral resolution ,business ,Ultraviolet - Abstract
We present the calibration of the Swift UVOT grisms, of which there are two, providing low-resolution field spectroscopy in the ultraviolet and optical bands respectively. The UV grism covers the range λ1700-5000 u with a spectral resolution (λ/�λ) of 75 at λ2600 u for source magnitudes of u=10-16 mag, while the visible grism covers the range λ2850-6600 u with a spectral resolution of 100 at λ4000 u for source magnitudes of b=12-17 mag. This calibration extends over all detector positions, for all modes used during operations. The wavelength accuracy (1-sigma) is 9 u in the UV grism clocked mode, 17 u in the UV grism nominal mode and 22 u in the visible grism. The range below λ2740 u in the UV grism and λ5200 u in the visible grism never suffers from overlapping by higher spectral orders. The flux calibration of the grisms includes a correction we developed for coincidence loss in the detector. The error in the coincidence loss correction is less than 20%. The position of the spectrum on the detector only affects the effective area (sensitivity) by a few percent in the nominal modes, but varies substantially in the clocked modes. The error in the effective area is from 9% in the UV grism clocked mode to 15% in the visible grism clocked mode .
- Published
- 2015
33. Predicting the Starquakes in PSR J0537−6910
- Author
-
William W. Zhang, John Middleditch, Q. Daniel Wang, Eric V. Gotthelf, and F. E. Marshall
- Subjects
Physics ,Astrophysics (astro-ph) ,Single pulse ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Rotation ,Glitch ,Pulse (physics) ,Amplitude ,Pulsar ,Space and Planetary Science ,Rotational axis ,Large Magellanic Cloud - Abstract
We report on more than 7 years of monitoring of PSR J0537-6910, the 16 ms pulsar in the Large Magellanic Cloud, using data acquired with the RXTE. During this campaign the pulsar experienced 23 sudden increases in frequency (``glitches'') amounting to a total gain of over six ppm of rotation frequency superposed on its gradual spindown of d(nu)/d(t) = -2e-10 Hz/s. The time interval from one glitch to the next obeys a strong linear correlation to the amplitude of the first glitch, with a mean slope of about 400 days ppm (6.5 days per uHz), such that these intervals can be predicted to within a few days, an accuracy which has never before been seen in any other pulsar. There appears to be an upper limit of ~40 uHz for the size of glitches in_all_ pulsars, with the 1999 April glitch of J0537 as the largest so far. The change in the spindown of J0537 across the glitches, Delta(d(nu)/d(t)), appears to have the same hard lower limit of -1.5e-13 Hz/s, as, again, that observed in all other pulsars. The spindown continues to increase in the long term, d(d(nu)/d(t))/d(t) = -1e-21 Hz/s/s, and thus the timing age of J0537 (-0.5 nu d(nu)/d(t)) continues to decrease at a rate of nearly one year every year, consistent with movement of its magnetic moment away from its rotational axis by one radian every 10,000 years, or about one meter per year. J0537 was likely to have been born as a nearly-aligned rotator spinning at 75-80 Hz, with a |d(nu)/d(t)| considerably smaller than its current value of 2e-10 Hz/s. The pulse profile of J0537 consists of a single pulse which is found to be flat at its peak for at least 0.02 cycles., Comment: 54 pages, 12 figures. Accepted for publication in The Astrophysical Journal. Cleaner figure 2. V4 -- in line with version accepted by ApJ
- Published
- 2006
34. GRB 051210: Swift detection of a short gamma ray burst
- Author
-
P. T. O'Brien, D. B. Fox, P. Romano, H. A. Krimm, G. Cusumano, A. Moretti, F. E. Marshall, G. Chincarini, N. Gehrels, Teresa Mineo, Peter Mészáros, S. D. Barthelmy, Bing Zhang, Sergio Campana, P. Giommi, V. Mangano, David N. Burrows, M. Perri, M. Capalbi, D. M. Palmer, G. Tagliaferri, and V. La Parola
- Subjects
Physics ,Photon ,Field (physics) ,Astrophysics (astro-ph) ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Light curve ,Power law ,law.invention ,Afterglow ,Space and Planetary Science ,law ,Absorption (electromagnetic radiation) ,Gamma-ray burst ,Flare - Abstract
The short/hard GRB051210 was detected and located by the Swift-BAT instrument and rapidly pointed towards by the narrow field instrumens. The XRT was able to observe a bright X-ray afterglow, one of the few ever observed for this class of bursts. We present the analysis of the prompt and afterglow emission of this event The BAT spectrum is a power-law with photon index 1.1 +/-0.3. The X-ray light curve decays with slope 2.58+/-0.11 and shows a small flare in the early phases. The spectrum can be described with a power law with photon index 1.54+/-0.16 and absorption (7.5 (-3.2, +4.3)*10^20 cm-2 We find that the X-ray emission is consistent with the hypothesis that we are observing the curvature effect of a GRB occurred in a low density medium, with no detectable afterglow. We estimate the density of the circumburst medium to be lower than 4*10^-3 cm^-3. We also discuss different hypothesis on the possible origin of the flare., Comment: 5 pages, 3 figures, submitted to A&A Letters
- Published
- 2006
35. SwiftUVOT Observations of X‐Ray Flash 050406
- Author
-
P. W. A. Roming, K. O. Mason, Katherine E. McGowan, Martin Still, J. P. Osborne, S. T. Holland, Neil Gehrels, M. J. Page, Patricia Schady, Bing Zhang, A. Cucchiara, C. Gronwall, M. de Pasquale, P. T. Boyd, F. E. Marshall, A. J. Blustin, and J. A. Nousek
- Subjects
Physics ,Astrophysics::High Energy Astrophysical Phenomena ,X-ray ,Flux ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Light curve ,Redshift ,Afterglow ,Flash (photography) ,Space and Planetary Science ,Exponential decay ,Visible spectrum - Abstract
We present Swift-UVOT data on the optical afterglow of the X-ray flash of 2005 April 6 (XRF 050406) from 88s to \sim 10^5s after the initial prompt gamma-ray emission. Our observations in the V, B and U bands are the earliest that have been taken of an XRF optical counterpart. Combining the early -time optical temporal and spectral properties with \gamma- and simultaneous X-ray data taken with the BAT and XRT telescopes on-board Swift, we are able to constrain possible origins of the XRF. The prompt emission had a FRED profile (fast-rise, exponential decay) with a duration of T_90 = 5.7\pm 0.2s, putting it at the short end of the long-burst duration distribution. The absence of photoelectric absorption red-ward of 4000 \AA in the UV/optical spectrum provides a firm upper limit of z\leq 3.1 on the redshift, thus excluding a high redshift as the sole reason for the soft spectrum. The optical light curve is consistent with a power-law decay with slope alpha = -0.75\pm 0.26 (F_{\nu}\propto t^{\alpha}), and a maximum occurring in the first 200s after the initial gamma-ray emission. The softness of the prompt emission is well described by an off-axis structured jet model, which is able to account for the early peak flux and shallow decay observed in the optical and X-ray bands.
- Published
- 2006
36. SwiftPanchromatic Observations of the Bright Gamma‐Ray Burst GRB 050525a
- Author
-
A. J. Blustin, D. Band, S. Barthelmy, P. Boyd, M. Capalbi, S. T. Holland, F. E. Marshall, K. O. Mason, M. Perri, T. Poole, P. Roming, S. Rosen, P. Schady, M. Still, B. Zhang, L. Angelini, L. Barbier, A. Beardmore, A. Breeveld, D. N. Burrows, J. R. Cummings, J. Canizzo, S. Campana, M. M. Chester, G. Chincarini, L. R. Cominsky, A. Cucchiara, M. de Pasquale, E. E. Fenimore, N. Gehrels, P. Giommi, M. Goad, C. Gronwall, D. Grupe, J. E. Hill, D. Hinshaw, S. Hunsberger, K. C. Hurley, M. Ivanushkina, J. A. Kennea, H. A. Krimm, P. Kumar, W. Landsman, V. La Parola, C. B. Markwardt, K. McGowan, P. Meszaros, T. Mineo, A. Moretti, A. Morgan, J. Nousek, P. T. O’Brien, J. P. Osborne, K. Page, M. J. Page, D. M. Palmer, A. M. Parsons, J. Rhoads, P. Romano, T. Sakamoto, G. Sato, G. Tagliaferri, J. Tueller, A. A. Wells, and N. E. White
- Subjects
Physics ,Jet (fluid) ,Astrophysics::High Energy Astrophysical Phenomena ,Astrophysics (astro-ph) ,FOS: Physical sciences ,Flux ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Light curve ,Power law ,Redshift ,Afterglow ,Interstellar medium ,Space and Planetary Science ,Gamma-ray burst - Abstract
The bright gamma-ray burst GRB050525a has been detected with the Swift observatory, providing unique multiwavelength coverage from the very earliest phases of the burst. The X-ray and optical/UV afterglow decay light curves both exhibit a steeper slope ~0.15 days after the burst, indicative of a jet break. This jet break time combined with the total gamma-ray energy of the burst constrains the opening angle of the jet to be 3.2 degrees. We derive an empirical `time-lag' redshift from the BAT data of z_hat = 0.69 +/- 0.02, in good agreement with the spectroscopic redshift of 0.61. Prior to the jet break, the X-ray data can be modelled by a simple power law with index alpha = -1.2. However after 300 s the X-ray flux brightens by about 30% compared to the power-law fit. The optical/UV data have a more complex decay, with evidence of a rapidly falling reverse shock component that dominates in the first minute or so, giving way to a flatter forward shock component at later times. The multiwavelength X-ray/UV/Optical spectrum of the afterglow shows evidence for migration of the electron cooling frequency through the optical range within 25000 s. The measured temporal decay and spectral indices in the X-ray and optical/UV regimes compare favourably with the standard fireball model for Gamma-ray bursts assuming expansion into a constant density interstellar medium., Comment: 31 pages, 7 figures, referee comments implemented, typo corrected in author list, accepted by ApJ
- Published
- 2006
37. The binary period and outburst behaviour of the Small Magellanic Cloud X-ray binary pulsar system SXP504
- Author
-
W. R. T. Edge, M. J. Coe, J. L. Galache, V. A. McBride, R. H. D. Corbet, A. T. Okazaki, S. Laycock, C. B. Markwardt, F. E. Marshall, and A. Udalski
- Subjects
Physics ,010308 nuclear & particles physics ,Milky Way ,X-ray binary ,Astronomy and Astrophysics ,Astrophysics ,Orbital period ,01 natural sciences ,Stars ,Gravitational lens ,Pulsar ,Space and Planetary Science ,0103 physical sciences ,Satellite galaxy ,Small Magellanic Cloud ,010303 astronomy & astrophysics - Abstract
A probable binary period has been detected in the optical counterpart to the X-raysource CXOU J005455.6-724510 = RX J0054.9-7245 = AXJ0054.8-7244 = SXP504 inthe Small Magellanic Cloud. This source was detected by Chandra on 04 Jul 2002and subsequently observed by XMM-Newton on 18 Dec 2003. The source is coincidentwith an Optical Gravitational Lensing (OGLE) object in the lightcurves of whichseveral optical outburst peaks are visible at ∼ 268 day intervals. Timing analysisshows a period of 268.6±0.1 days at > 99% significance. Archival Rossi X-ray TimingExplorer (RXTE) data for the 504s pulse-period has revealed detections which cor-respond closely with predicted or actual peaks in the optical data. The relationshipbetween this orbital period and the pulse period of 504s is within the normal variancefound in the Corbet diagram.Key words: Be stars - X-rays: binaries: Magellanic Clouds. 1 INTRODUCTIONThe Magellanic Clouds are a pair of satellite galaxies whichare gravitationally bound to our own but which have struc-tural and chemical characteristics differing significantly fromeach other, and from the Milky Way. These differences arelikely to be reflected in the properties of different stellarpopulations. The Small Magellanic cloud (SMC) is locatedat a distance of about 60 kpc (Harries, Hilditch, & Howarth2003) and centred on a position of R.A. 1hr Dec. -73
- Published
- 2005
38. X-ray Pulsars in the Small Magellanic Cloud
- Author
-
F. E. Marshall, Jose Luis Galache, M. J. Coe, Robin H. D. Corbet, Silas Laycock, and C. B. Markwardt
- Subjects
Physics ,Astrophysics::High Energy Astrophysical Phenomena ,Proportional counter ,Astronomy ,Astronomy and Astrophysics ,Astrophysics ,Orbital period ,Galaxy ,Statistics::Computation ,Hubble sequence ,symbols.namesake ,Pulsar ,Space and Planetary Science ,Relative mass ,symbols ,Astrophysics::Solar and Stellar Astrophysics ,Small Magellanic Cloud ,Astrophysics::Galaxy Astrophysics - Abstract
The SMC is now known to contain many more transient X-ray pulsars than would be expected based on a simple scaling of the number of such sources in the Galaxy by the relative mass of the SMC. We have been conducting regular monitoring observations of the SMC with the Proportional Counter Array on the Rossi X-ray Timing Explorer since 1997. This has resulted in the discovery of many of these X-ray pulsars and also provided orbital period measurements from detections of regular outbursts. We can now investigate the differences and similarities of the Galactic and SMC X-ray pulsar populations and consider the origin of the huge SMC X-ray pulsar over-abundance.
- Published
- 2005
39. NuSTAR observatory science operations: on-orbit acclimation
- Author
-
Fiona A. Harrison, William W. Craig, Karl Forster, Suzanne R. Dodd, Daniel Stern, Brian W. Grefenstette, Craig B. Markwardt, Kristin K. Madsen, F. E. Marshall, Hiromasa Miyasaka, Peck, Alison B., Benn, Chris R., and Seaman, Robert L.
- Subjects
Telescope ,Physics ,High energy ,Observatory ,law ,Full service ,Systems engineering ,Orbit (dynamics) ,Orbital mechanics ,Space Science ,Space observatory ,Remote sensing ,law.invention - Abstract
The Nuclear Spectroscopic Telescope Array (NuSTAR) is the first focusing high energy (3-79 keV) X-ray observatory. The NuSTAR project is led by Caltech, which hosts the Science Operations Center (SOC), with mission operations managed by UCB Space Sciences Laboratory. We present an overview of NuSTAR science operations and describe the on-orbit performance of the observatory. The SOC is enhancing science operations to serve the community with a guest observing program beginning in 2015. We present some of the challenges and approaches taken by the SOC to operating a full service space observatory that maximizes the scientific return from the mission.
- Published
- 2014
40. GRB 130427A: A nearby ordinary monster
- Author
-
D. Bersier, T. A. Pritchard, B. Sbarufatti, P. D'Avanzo, Valerio D'Elia, A. Maselli, G. Calderone, Drejc Kopač, Paul Kuin, G. Tagliaferri, Phil Evans, J. A. Nousek, T. Sakamoto, H. Hanayama, Giacomo Vianello, Nobuyuki Kawai, J. P. Osborne, A. P. Beardmore, B. Wiegand, P. Romano, David N. Burrows, Neil Gehrels, A. Gomboc, M. Perri, Iain A. Steele, L. Nava, Taketoshi Yoshii, S. R. Oates, Nial R. Tanvir, S. D. Barthelmy, Chryssa Kouveliotou, C. Pagani, C. Guidorzi, Andrew J. Levan, Giancarlo Ghirlanda, J. A. Kennea, M. Capalbi, Shiho Kobayashi, M. de Pasquale, J. R. Cummings, Y. Yatsu, A. Melandri, M. G. Bernardini, R. Harrison, D. Malesani, V. La Parola, Giancarlo Cusumano, Klaas Wiersema, M. J. Page, P. T. O'Brien, Sergio Campana, B.-B. Zhang, V. Mangano, Y. Saito, James Chiang, F. E. Marshall, J. Japelj, K. L. Page, Stefano Covino, Carole Mundell, Fabio Virgili, Motoko Serino, Gabriele Ghisellini, Daisuke Kuroda, D. Fugazza, Ruben Salvaterra, INAF - Osservatorio Astronomico di Brera (OAB), Istituto Nazionale di Astrofisica (INAF), Racah Institute of Physics (Racah Institute of Physics), The Hebrew University of Jerusalem (HUJ)-Racah Institute of Physics, AstroParticule et Cosmologie (APC (UMR_7164)), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), RIKEN - Institute of Physical and Chemical Research [Japon] (RIKEN), Istituto di Astrofisica e Planetologia Spaziali - INAF (IAPS), Kyoto University [Kyoto], Institut de médecine moléculaire de Rangueil (I2MR), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-IFR150-Institut National de la Santé et de la Recherche Médicale (INSERM), Astrophysics Research Institute [Liverpool] (ARI), Liverpool John Moores University (LJMU), Chimie Et Interdisciplinarité : Synthèse, Analyse, Modélisation (CEISAM), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), ASI-Science Data Center, Rome, NASA Goddard Space Flight Center (GSFC), Faculty of Mathematics and Physics [Ljubljana] (FMF), University of Ljubljana, Dark Cosmology Centre (DARK), Niels Bohr Institute [Copenhagen] (NBI), Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU)-Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU), Mullard Space Science Laboratory (MSSL), University College of London [London] (UCL), Osservatorio Astrofisico di Catania, Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency [Sagamihara] (JAXA), INAF-IASF Milano, Department of Physics and Astronomy [Leicester], University of Leicester, Institute of Zoology, Universität Regensburg (UR), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Kyoto University, Université de Toulouse (UT)-Université de Toulouse (UT)- Institut Fédératif de Recherche Bio-médicale Institution (IFR150)-Institut National de la Santé et de la Recherche Médicale (INSERM), Université de Nantes (UN)-Université de Nantes (UN)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), University of Copenhagen = Københavns Universitet (UCPH)-University of Copenhagen = Københavns Universitet (UCPH)-Faculty of Science [Copenhagen], and University of Copenhagen = Københavns Universitet (UCPH)-University of Copenhagen = Københavns Universitet (UCPH)
- Subjects
media_common.quotation_subject ,Astrophysics::High Energy Astrophysical Phenomena ,FOS: Physical sciences ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,Luminosity ,0103 physical sciences ,010306 general physics ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,ComputingMilieux_MISCELLANEOUS ,media_common ,QB ,High Energy Astrophysical Phenomena (astro-ph.HE) ,Physics ,[PHYS]Physics [physics] ,Multidisciplinary ,Gamma ray ,GRB 130427A ,Light curve ,Universe ,Afterglow ,Stars ,Astrophysics - High Energy Astrophysical Phenomena ,Gamma-ray burst ,[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] - Abstract
Long-duration Gamma-Ray Bursts (GRBs) are an extremely rare outcome of the collapse of massive stars, and are typically found in the distant Universe. Because of its intrinsic luminosity ($L\sim 3 \times 10^{53}$ erg s$^{-1}$) and its relative proximity ($z=0.34$), GRB 130427A was a unique event that reached the highest fluence observed in the gamma-ray band. Here we present a comprehensive multiwavelength view of GRB 130427A with Swift, the 2-m Liverpool and Faulkes telescopes and by other ground-based facilities, highlighting the evolution of the burst emission from the prompt to the afterglow phase. The properties of GRB 130427A are similar to those of the most luminous, high-redshift GRBs, suggesting that a common central engine is responsible for producing GRBs in both the contemporary and the early Universe and over the full range of GRB isotropic energies., 64 pages, 11 figures; published in Science. Update for a few references and correction of a typo in the name of one of the authors
- Published
- 2014
41. A Phase-connected Braking Index Measurement for the Large Magellanic Cloud Pulsar PSR B0540−69
- Author
-
Q. D. Wang, John Middleditch, Eric V. Gotthelf, F. E. Marshall, and W. W. Zhang
- Subjects
Physics ,Pulsar ,Space and Planetary Science ,Millisecond pulsar ,Phase (waves) ,Astronomy ,Astronomy and Astrophysics ,Astrophysics ,Glitch (astronomy) ,Large Magellanic Cloud ,Second derivative - Abstract
We report the results of an extensive monitoring campaign of PSR B0540-69, the 50 ms pulsar in the Large Magellanic Cloud, using data acquired with the Rossi X-Ray Timing Explorer. A set of 45 pointed X-ray observations spanning 1.2 yr reveals a steady spin-down interrupted by a single glitch event, the first recorded for this young, rotation-powered pulsar. The quality of the data allowed us to perform a pulse-timing analysis that successfully maintains cycle count between observations, after allowing for the observed glitch. The glitch event occurred on MJD 51,325 ± 45 (90% CL error) and is characterized by a change in frequency of Δν/ν = (1.90 ± 0.04) × 10-9 and in frequency derivative of Δ/ = (8.5 ± 0.5) × 10-5. By phase-linking the data set we provide a definitive measurement of the spin frequency of the pulsar and its first and second derivatives. These translate into a braking index of n = 1.81 ± 0.07, significantly lower than reported previously for this source using measurements that could not be phase-linked unambiguously.
- Published
- 2001
42. The Discovery of an Outburst and Pulsed X-Ray Flux from SMC X-2 Using the [ITAL]Rossi X-Ray Timing Explorer[/ITAL]
- Author
-
Robin H. D. Corbet, M. J. Coe, Silas Laycock, F. E. Marshall, and G. Handler
- Subjects
Physics ,Photometry (optics) ,Space and Planetary Science ,X-ray ,Proportional counter ,Astronomy and Astrophysics ,Astrophysics - Abstract
Rossi X-Ray Timing Explorer (RXTE) All-Sky Monitor observations of SMC X-2 show that the source experienced an outburst in 2000 January-April reaching a peak luminosity of greater than ~1038 ergs s-1. RXTE Proportional Counter Array observations during this outburst reveal the presence of pulsations with a 2.37 s period. However, optical photometry of the optical counterpart shows that the source was still significantly fainter than it was more than a half a year after the outburst in the 1970s when SMC X-2 was discovered.
- Published
- 2001
43. Observation of X-ray Lines from a Gamma-Ray Burst (GRB991216): Evidence of Moving Ejecta from the Progenitor
- Author
-
T. Murakami, M. Feroci, H. V. Bradt, Enrico Costa, John Heise, T. Takeshima, N. Kawai, R. M. Kippen, Gordon P. Garmire, G. Stratta, F. E. Marshall, Mario Vietri, Michael R. Garcia, A. Yoshida, L. Piro, Jules P. Halpern, Dale A. Frail, Kevin Hurley, F. Frontera, V. V. Sokolov, and Peter Mészáros
- Subjects
Physics ,Multidisciplinary ,Astrophysics::High Energy Astrophysical Phenomena ,Astrophysics (astro-ph) ,FOS: Physical sciences ,Astronomy ,Lyman-alpha line ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Redshift ,Afterglow ,Supernova ,Astrophysics::Solar and Stellar Astrophysics ,Astrophysics::Earth and Planetary Astrophysics ,Emission spectrum ,GRB 011211 ,Gamma-ray burst ,Ejecta ,Astrophysics::Galaxy Astrophysics - Abstract
We report on the discovery of two emission features observed in the X-ray spectrum of the afterglow of the gamma-ray burst (GRB) of 16 Dec. 1999 by the Chandra X-Ray Observatory. These features are identified with the Ly$_{\alpha}$ line and the narrow recombination continuum by hydrogenic ions of iron at a redshift $z=1.00\pm0.02$, providing an unambiguous measurement of the distance of a GRB. Line width and intensity imply that the progenitor of the GRB was a massive star system that ejected, before the GRB event, $\approx 0.01 \Ms$ of iron at a velocity $\approx 0.1 c$, probably by a supernova explosion., Comment: 11 pages,2 fig.s, link to the published paper in Science, 290, 955 (2000) through http://www.ias.rm.cnr.it/grb/gb991216.html
- Published
- 2000
44. Intensive X-ray Monitoring of the 16ms Crab-like Pulsar PSR J0537 – 6910
- Author
-
John Middleditch, Eric V. Gotthelf, F. E. Marshall, Q. D. Wang, and W. W. Zhang
- Subjects
Physics ,Neutron star ,Pulsar ,Millisecond pulsar ,Crab Pulsar ,Astrophysics::High Energy Astrophysical Phenomena ,Astrophysics::Instrumentation and Methods for Astrophysics ,Astronomy ,Glitch (astronomy) ,Supernova remnant ,Large Magellanic Cloud ,Astrophysics::Galaxy Astrophysics ,Maximum rate - Abstract
The recently discovered pulsar PSR J0537-6910 is the most rapidly rotating young pulsar known. This latest example of a Crab-like pulsar, located in the supernova remnant N157B in the Large Magellanic Cloud, is rotating twice as fast as the Crab pulsar. With a characteristic age of 5000 years, it is also the oldest known example of a Crab-like pulsar and was likely rotating close to the maximum rate for a neutron star when it was born. Here we report preliminary results from an intensive monitoring campaign of X-ray observations acquired with the Rossi X-ray Timing Explorer that began in January 1999. These observation have revealed a large glitch event in the pulse timing during the first six month of our campaign, consistent with those suggested by sparse observations dating back to 1993. The current evolution of the rotation rate of PSR J0537-6910 provides a unique probe of the internal structure of neutron stars and constraints on possible pulsar emission mechanisms.
- Published
- 2000
45. ASCA observations of two new X-ray pulsars near SMC X-3
- Author
-
R. H. D. Corbet, M. Ozaki, F. E. Marshall, and J. C. Lochner
- Subjects
Physics ,Atmospheric Science ,Geophysics ,Pulsar ,Space and Planetary Science ,Position (vector) ,Target of opportunity ,X-ray ,Aerospace Engineering ,General Earth and Planetary Sciences ,Astronomy and Astrophysics ,Field of view ,Astrophysics - Abstract
ASCA carried out target of opportunity observations centered on the position of SMC X-3 following the report of a detection of emission from SMC X-3 with RXTE. However, no source was detected at the position of SMC X-3 itself, instead two new pulsars in the SMC were found within the ASCA field of view with periods of 46.6 and 91.1 sec.
- Published
- 2000
46. X-Ray and Extreme Ultraviolet Emission from Comet P/Encke 1997
- Author
-
Joachim Trümper, Michael D. Desch, Konrad Dennerl, F. E. Marshall, Damian J. Christian, Robert Petre, Carey M. Lisse, Jakob Englhauser, and Steven L. Snowden
- Subjects
Physics ,Current sheet ,Solar wind ,Space and Planetary Science ,Comet tail ,Extreme ultraviolet ,Comet nucleus ,Comet ,Astronomy ,Astronomy and Astrophysics ,Magnetic reconnection ,Astrophysics ,Light curve - Abstract
In an effort to understand the newly discovered phenomenon of cometary X-ray emission, we have obtained observations of the short period (3.3 years), well-studied comet 2P/Encke (Encke) during its July 1997 close approach to Earth. Extended, variable emission on the sunward side of the nucleus was found in the Rontgen X-ray satellite High Resolution Imager (HRI) at 0.090–0.75 keV and in the Extreme Ultraviolet Explorer (EUVE) scanner telescopes' Lexan B 0.090- to 0.28-keV and Al/Ti/C 0.050- to 0.16-keV bandpasses; useful upper limits were found in the Ti/Sb/Al 0.020- to 0.040-eV bandpass. Similar to our results for C/Hyakutake, the emission morphology was roughly symmetric with respect to a vector from the comet's nucleus toward the Sun, with a light curve consisting of a slowly varying baseline emission and a large impulsive event on 7 July 1997 with a time scale of ∼3 h and an amplitude of ∼3 times the baseline. A count rate of ∼0.17 counts s−1 in the HRI was measured for the slowly varying emission, corresponding to a total luminosity Lx of 4×1014 erg s−1. Unlike Hyakutake, however, the bulk of the emission clearly originates outside the comet's bowshock, arguing against the magnetic reconnection and plasma dust emission models. The comet's lightcurve does not correlate with the solar X-ray lightcurve, ruling out scattering of solar X-rays as the emission mechanism. The multiwavelength HRI/EUVE photometry is inconsistent with the Haberli et al. (1997, Science 276, 939–942) charge transfer, plasma dust, and attogram dust models of cometary X-ray emission and is consistent with the Wegmann et al. (1988, Planet. Space Sci. 46, 603–612) charge exchange, 0.15- to 0.45-keV thermal bremsstrahlung, and photon index 1.6–2.0 power law models. While the impulsive event correlates very well with the passage of a solar magnetic field boundary at the Earth and an increase in the solar wind particle flux, it is not coincident, according to current models of the solar wind magnetic current sheet, with the passage of the sector boundary by the comet, suggesting that new models of the current sheet are necessary.
- Published
- 1999
47. Rossi X‐Ray Timing ExplorerObservations of the X‐Ray Pulsar XTE J1855−026: A Possible New Supergiant System
- Author
-
F. E. Marshall, Robin H. D. Corbet, T. Takeshima, and Andrew G. Peele
- Subjects
Physics ,Astrophysics::High Energy Astrophysical Phenomena ,Binary number ,Astronomy and Astrophysics ,Astrophysics ,Galactic plane ,Orbital period ,Neutron star ,Space and Planetary Science ,Primary (astronomy) ,Astrophysics::Solar and Stellar Astrophysics ,Emission spectrum ,Supergiant ,Astrophysics::Galaxy Astrophysics ,X-ray pulsar - Abstract
A new X-ray source, XTE J1855-026, was discovered during RXTE scans along the galactic plane. The source shows pulsations at a period of 361 s and also modulation at a period of 6.1 days which we interpret as the orbital period of the system. The X-ray spectrum above ~3 keV can be fitted with an absorbed power law model with a high-energy cut-off, and an iron emission line at approximately 6.4 keV. We interpret these results as indicating that XTE J1855-026 is likely to consist of a neutron star accreting from the wind of an O or B supergiant primary. A less likely interpretation is that XTE J1855-026 is instead a Be/neutron star binary, in which case it would have the shortest known orbital period for such a system.
- Published
- 1999
48. RXTE measurement of the diffuse X-ray emission from the galactic ridge: Implications for the energetics of the interstellar medium
- Author
-
F. E. Marshall and Azita Valinia
- Subjects
Physics ,Nuclear and High Energy Physics ,Astrophysics::High Energy Astrophysical Phenomena ,Galactic ridge ,Bremsstrahlung ,Astronomy ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Power law ,Atomic and Molecular Physics, and Optics ,Interstellar medium ,Supernova ,Thin disk ,Supernova remnant ,Absorption (electromagnetic radiation) ,Astrophysics::Galaxy Astrophysics - Abstract
The diffuse X-ray emission from the thin disk surrounding the Galactic mid-plane (the so-called Galactic ridge) was measured with RXTE PCA in order to determine the spatial extent, spectral nature, and origin of the emission. Spatial analysis of the emission in the central 30° of the plane in Galactic longitude reveals the presence of a thin component of width ≈0°.2 and a broad component that can be approximated as a Gaussian distribution with FWHM of ≈8°. The spectrum can be interpreted as the superposition of the two spatial components with differing amount of absorption. Each spatial component can be modelled with a Raymond-Smith plasma component of temperature ∼ 2 keV and a power law component with photon index of ∼ 2.5. Based on these findings, we argue that the temperature of the hot phase of the Interstellar Medium (ISM) is less than the previously reported values of 5 – 15 keV. We find that a supernova explosion rate of ∼ 1 – 5 per century is adequate to power the thermal emission from the ridge. We discuss the origin of the emission in the hard X-ray band in terms of non-thermal bremsstrahlung of accelerated electrons and protons in supernova remnant (SNR) sites.
- Published
- 1999
49. RXTE observations of GRB afterglows
- Author
-
D. Smith, H. V. Bradt, C. R. Robinson, Chryssa Kouveliotou, Toshiaki Takeshima, Marc Kippen, Robert D. Preece, Robin H. D. Corbet, Alan M. Levine, Scott Barthelmy, Azita Valinia, Kevin Hurley, Valerie Connaughton, Ron Remillard, Jean H. Swank, and F. E. Marshall
- Subjects
Physics ,Nuclear and High Energy Physics ,Astrophysics::High Energy Astrophysical Phenomena ,Astronomy ,Cosmic ray ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Sensitivity limit ,Gamma-ray burst ,Atomic and Molecular Physics, and Optics ,Afterglow - Abstract
Variable X-ray sources that appear to be the afterglows of the strong gamma-ray bursts GRB 970616 and GRB 970828 have been discovered with the RXTE PCA. First seen less than 4 hours after the burst, the flux from the sources decreased with time. Although near the sensitivity limit of the PCA, the sources are the brightest afterglows yet seen in X-rays. Similar observations of two other bursts did not detect any afterglows. These results are part of a continuing collaboration between RXTE, BATSE, and IPN scientists to rapidly detect X-ray afterglows of bright gamma-ray bursts.
- Published
- 1999
50. RXTEMeasurement of the Diffuse X‐Ray Emission from the Galactic Ridge: Implications for the Energetics of the Interstellar Medium
- Author
-
F. E. Marshall and Azita Valinia
- Subjects
Physics ,Astrophysics::High Energy Astrophysical Phenomena ,Galactic ridge ,Astrophysics (astro-ph) ,Bremsstrahlung ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Electron ,Power law ,Interstellar medium ,Thin disk ,Space and Planetary Science ,Ionization ,Emission spectrum ,Astrophysics::Galaxy Astrophysics - Abstract
(Abridged) The diffuse X-ray emission from the thin disk surrounding the Galactic mid-plane (the so-called Galactic ridge) was measured with RXTE PCA in order to determine the spatial extent, spectral nature, and origin of the emission. Spatial examination of the diffuse emission in the central 30 deg of the plane in Galactic longitude reveals the presence of two components: a thin disk of full width less than 0.5 deg centered roughly on the Galactic mid-plane, and a broad component which can be approximated as a Gaussian distribution with FWHM of about 4 deg. Spectral examination of the emission clearly reveals the presence of a hard power law tail above 10 keV and an emission line from He-like iron, indicating both thermal and possibly non-thermal origins for the diffuse emission. The averaged spectrum from the ridge in the 3-35 keV band can be modelled with a Raymond-Smith plasma component of temperature ~2-3 keV and a power law component of photon index ~1.8. Based on this finding, we argue that the temperature of the hot phase of the Interstellar Medium (ISM) is less than the previously reported values of 5-15 keV. We find that a SN explosion rate of less than 5 per century is adequate to power the thermal emission from the ridge. We speculate that bremsstrahlung of accelerated electrons and protons in SNR sites can play a significant role in producing the hard tail of the spectrum. Moreover, their collisional losses can play a major role in the ionization of the ISM., Accepted for Publication in the Astrophysical Journal, 26 pages, 11 figures (including one color plate)
- Published
- 1998
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.