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271. Optical light curves of {gamma}-ray bursts
ID:
ivo://CDS.VizieR/J/A+A/557/A12
Title:
Optical light curves of {gamma}-ray bursts
Short Name:
J/A+A/557/A12
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a comprehensive analysis of the optical and X-ray light curves (LCs) and spectral energy distributions (SEDs) of a large sample of gamma-ray burst (GRB) afterglows to investigate the relationship between the optical and X-ray emission after the prompt phase. We consider all data available in the literature, which where obtained with different instruments. We collected the optical data from the literature and determined the shapes of the optical LCs. Then, using previously presented X-ray data we modeled the optical/X-ray SEDs. We studied the SED parameter distributions and compared the optical and X-ray LC slopes and shapes.
272. Optical monitoring of GeV loud blazars
ID:
ivo://CDS.VizieR/J/ApJ/522/846
Title:
Optical monitoring of GeV loud blazars
Short Name:
J/ApJ/522/846
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present optical monitoring between 1994 February and 1997 December of 10 gamma-ray-loud blazars included in our blazar monitoring program. Most of the monitored objects show significant rapid variations. The typical minimum variability timescale in the optical range is about 1 hour. We have analyzed the relationships between optical variability and gamma-ray variability, and discussed theoretical models for the gamma-rayloud blazar emission.
273. Optical/near-IR observations of GRB 080310
ID:
ivo://CDS.VizieR/J/MNRAS/421/2692
Title:
Optical/near-IR observations of GRB 080310
Short Name:
J/MNRAS/421/2692
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present broad-band multiwavelength observations of GRB 080310 at redshift z=2.43. This burst was bright and long-lived, and unusual in having extensive optical and near-infrared (IR) follow-up during the prompt phase. Using these data we attempt to simultaneously model the gamma-ray, X-ray, optical and IR emission using a series of prompt pulses and an afterglow component.
274. Optical obs. of GRB 180205A with COATLI
ID:
ivo://CDS.VizieR/J/ApJ/872/118
Title:
Optical obs. of GRB 180205A with COATLI
Short Name:
J/ApJ/872/118
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present optical photometry of the afterglow of the long GRB 180205A with the COATLI telescope from 217s to about 5d after the Swift/BAT trigger. We analyze this photometry in conjunction with the X-ray light curve from Swift/XRT. The late-time light curves and spectra are consistent with the standard forward-shock scenario. However, the early-time optical and X-ray light curves show atypical behavior; the optical light curve exhibits a flat plateau while the X-ray light curve shows a flare. We explore several scenarios and conclude that the most likely explanation for the early behavior is late activity of the central engine.
275. Optical photometry of GRB 070610
ID:
ivo://CDS.VizieR/J/ApJ/678/1127
Title:
Optical photometry of GRB 070610
Short Name:
J/ApJ/678/1127
Date:
21 Oct 2021
Publisher:
CDS
Description:
GRB 070610 is a typical high-energy event with a duration of 5s. Yet within the burst localization we detect a highly unusual X-ray and optical transient, Swift J195509.6+261406. We see high-amplitude X-ray and optical variability on very short timescales even at late times. Using near-infrared imaging assisted by a laser guide star and adaptive optics, we identified the counterpart of Swift J195509.6+261406. Late-time optical and near-infrared imaging constrain the spectral type of the counterpart to be fainter than a K-dwarf, assuming it is of Galactic origin. It is possible that GRB 070610 and Swift J195509.6+261406 are unrelated sources. However, the absence of a typical X-ray afterglow from GRB 070610 in conjunction with the spatial and temporal coincidence of the two motivate us to suggest that the sources are related. The closest (imperfect) analog to Swift J195509.6+261406 is V4641 Sgr, an unusual black hole binary. We suggest that Swift J195509.6+261406 along with V4641 Sgr define a subclass of stellar black hole binaries-the fast X-ray novae. We further suggest that fast X-ray novae are associated with bursts of gamma rays. If so, GRB 070610 defines a new class of celestial gamma-ray bursts and these bursts dominate the long-duration GRB demographics.
276. Optical photometry of 4 millisecond pulsars
ID:
ivo://CDS.VizieR/J/ApJ/769/108
Title:
Optical photometry of 4 millisecond pulsars
Short Name:
J/ApJ/769/108
Date:
21 Oct 2021
Publisher:
CDS
Description:
In the last few years, over 43 millisecond radio pulsars have been discovered by targeted searches of unidentified {gamma}-ray sources found by the Fermi Gamma-Ray Space Telescope. A large fraction of these millisecond pulsars are in compact binaries with low-mass companions. These systems often show eclipses of the pulsar signal and are commonly known as black widows and redbacks because the pulsar is gradually destroying its companion. In this paper, we report on the optical discovery of four strongly irradiated millisecond pulsar companions. All four sources show modulations of their color and luminosity at the known orbital periods from radio timing. Light curve modeling of our exploratory data shows that the equilibrium temperature reached on the companion's dayside with respect to their nightside is consistent with about 10%-30% of the available spin-down energy from the pulsar being reprocessed to increase the companion's dayside temperature. This value compares well with the range observed in other irradiated pulsar binaries and offers insights about the energetics of the pulsar wind and the production of {gamma}-ray emission. In addition, this provides a simple way of estimating the brightness of irradiated pulsar companions given the pulsar spin-down luminosity. Our analysis also suggests that two of the four new irradiated pulsar companions are only partially filling their Roche lobe. Some of these sources are relatively bright and represent good targets for spectroscopic follow-up.
277. Optical properties of GRB afterglows
ID:
ivo://CDS.VizieR/J/ApJ/686/1209
Title:
Optical properties of GRB afterglows
Short Name:
J/ApJ/686/1209
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a multiwavelength analysis of 63 gamma-ray bursts observed with the world's three largest robotic optical telescopes, the Liverpool and Faulkes Telescopes (North and South). Optical emission was detected for 24 GRBs with brightnesses ranging from R=10 to 22mag in the first 10 minutes after the burst. By comparing optical and X-ray light curves from t=100 to ~106 seconds, we introduce four main classes, defined by the presence or absence of temporal breaks at optical and/or X-ray wavelengths. While 14/24 GRBs can be modeled with the forward-shock model, explaining the remaining 10 is very challenging in the standard framework even with the introduction of energy injection or an ambient density gradient. Early X-ray afterglows, even segments of light curves described by a power law, may be due to additional emission from the central engine. Thirty-nine GRBs in our sample were not detected and have deep upper limits (R<22mag) at early time. Of these, only 10 were identified by other facilities, primarily at near infrared wavelengths, resulting in a dark burst fraction of ~50%. Additional emission in the early-time X-ray afterglow due to late-time central engine activity may also explain some dark bursts by making the bursts brighter than expected in the X-ray band compared to the optical band.
278. Optical spectroscopy of 1LAC broad-line blazars
ID:
ivo://CDS.VizieR/J/ApJ/748/49
Title:
Optical spectroscopy of 1LAC broad-line blazars
Short Name:
J/ApJ/748/49
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report on optical spectroscopy of 165 flat spectrum radio quasars (FSRQs) in the Fermi 1LAC sample, which have helped allow a nearly complete study of this population. Fermi FSRQs show significant evidence for non-thermal emission even in the optical; the degree depends on the {gamma}-ray hardness. They also have smaller virial estimates of hole mass than the optical quasar sample. This appears to be largely due to a preferred (axial) view of the {gamma}-ray FSRQ and non-isotropic (H/R ~ 0.4) distribution of broad-line velocities. Even after correction for this bias, the Fermi FSRQs show higher mean Eddington ratios than the optical population. A comparison of optical spectral properties with Owens Valley Radio Observatory radio flare activity shows no strong correlation.
279. Opt/NIR obs. of 1FGLJ1417.7-4407 neutron star bin.
ID:
ivo://CDS.VizieR/J/ApJ/866/83
Title:
Opt/NIR obs. of 1FGLJ1417.7-4407 neutron star bin.
Short Name:
J/ApJ/866/83
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Fermi {gamma}-ray source 1FGL J1417.7-4407 (J1417) is a compact X-ray binary with a neutron star primary and a red giant companion in a ~5.4 days orbit. This initial conclusion, based on optical and X-ray data, was confirmed when a 2.66ms radio pulsar was found at the same location (and with the same orbital properties) as the optical/X-ray source. However, these initial studies found conflicting evidence about the accretion state and other properties of the binary. We present new optical, radio, and X-ray observations of J1417 that allow us to better understand this unusual system. We show that one of the main pieces of evidence previously put forward for an accretion disk-the complex morphology of the persistent H{alpha} emission line-can be better explained by the presence of a strong, magnetically driven stellar wind from the secondary and its interaction with the pulsar wind. The radio spectral index derived from VLA/ATCA observations is broadly consistent with that expected from a millisecond pulsar, further disfavoring an accretion disk scenario. X-ray observations show evidence for a double-peaked orbital light curve, similar to that observed in some redback millisecond pulsar binaries and likely due to an intrabinary shock. Refined optical light-curve fitting gives a distance of 3.1+/-0.6kpc, confirmed by a Gaia DR2 parallax measurement. At this distance the X-ray luminosity of J1417 is (1.0_-0.3_^+0.4^)x10^33^erg/s, which is more luminous than all known redback systems in the rotational-powered pulsar state, perhaps due to the wind from the giant companion. The unusual phenomenology of this system and its differing evolutionary path from redback millisecond pulsar binaries points to a new eclipsing pulsar "spider" subclass that is a possible progenitor of normal field millisecond pulsar binaries.
280. Parkes Multi-Beam Pulsar Survey. III.
ID:
ivo://CDS.VizieR/J/MNRAS/342/1299
Title:
Parkes Multi-Beam Pulsar Survey. III.
Short Name:
J/MNRAS/342/1299
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Parkes Multibeam Pulsar Survey has unlocked vast areas of the Galactic plane, which were previously invisible to earlier low-frequency and less-sensitive surveys. The survey has discovered more than 600 new pulsars so far, including many that are young and exotic. In this paper we report the discovery of 200 pulsars for which we present positional and spin-down parameters, dispersion measures, flux densities and pulse profiles. A large number of these new pulsars are young and energetic, and we review possible associations of {gamma}-ray sources with the sample of about 1300 pulsars for which timing solutions are known. Based on a statistical analysis, we estimate that about 19+/-6 associations are genuine. The survey has also discovered 12 pulsars with spin properties similar to those of the Vela pulsar, nearly doubling the known population of such neutron stars. Studying the properties of all known 'Vela-like' pulsars, we find their radio luminosities to be similar to normal pulsars, implying that they are very inefficient radio sources. Finally, we review the use of the newly discovered pulsars as Galactic probes and discuss the implications of the new NE2001 Galactic electron density model for the determination of pulsar distances and luminosities.