- ID:
- ivo://CDS.VizieR/J/ApJ/774/114
- Title:
- GRB 081007 and GRB 090424 light curves
- Short Name:
- J/ApJ/774/114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We discuss the results of the analysis of multi-wavelength data for the afterglows of GRB 081007 and GRB 090424, two bursts detected by Swift. One of them, GRB 081007, also shows a spectroscopically confirmed supernova, SN 2008hw, which resembles SN 1998bw in its absorption features, while the maximum magnitude may be fainter, up to 0.7mag, than observed in SN 1998bw. Bright optical flashes have been detected in both events, which allows us to derive solid constraints on the circumburst-matter density profile. This is particularly interesting in the case of GRB 081007, whose afterglow is found to be propagating into a constant-density medium, yielding yet another example of a gamma-ray burst (GRB) clearly associated with a massive-star progenitor which did not sculpt the surroundings with its stellar wind. There is no supernova component detected in the afterglow of GRB 090424, likely due to the brightness of the host galaxy, comparable to the Milky Way. We show that the afterglow data are consistent with the presence of both forward- and reverse-shock emission powered by relativistic outflows expanding into the interstellar medium. The absence of optical peaks due to the forward shock strongly suggests that the reverse-shock regions should be mildly magnetized. The initial Lorentz factor of outflow of GRB 081007 is estimated to be {Gamma}~200, while for GRB 090424 a lower limit of {Gamma}>170 is derived. We also discuss the prompt emission of GRB 081007, which consists of just a single pulse. We argue that neither the external forward-shock model nor the shock-breakout model can account for the prompt emission data and suggest that the single-pulse-like prompt emission may be due to magnetic energy dissipation of a Poynting-flux-dominated outflow or to a dissipative photosphere.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/560/A70
- Title:
- GRB 100621A unusual afterglow
- Short Name:
- J/A+A/560/A70
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- With the afterglow of GRB 100621A being the brightest detected so far in X-rays, and superb GROND coverage in the optical/near-infrared during the first few hours, an observational verification of basic fireball predictions seemed possible. In order to constrain the broad-band spectral energy distribution of the afterglow of GRB 100621A, dedicated observations were performed in the optical/near-infrared with the 7-channel Gamma-Ray Burst Optical and Near-infrared Detector (GROND) at the 2.2m MPG/ESO telescope, in the sub-millimeter band with the large bolometer array LABOCA at APEX, and at radio frequencies with ATCA. Utilizing also Swift X-ray observations, we attempt an interpretation of the observational data within the fireball scenario.
- ID:
- ivo://CDS.VizieR/J/A+A/508/593
- Title:
- GRB 080710 bright optical/NIR afterglow
- Short Name:
- J/A+A/508/593
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the optical/near-infrared light curve of the afterglow of GRB 080710 in the context of rising afterglows. Optical and near-infrared photometry was performed using the seven-channel imager GROND and the Tautenburg Schmidt telescope. X-ray data were provided by the X-ray Telescope onboard the Swift satellite. We construct an empirical light curve model using the available broadband data, which is well-sampled in the time and frequency domains.
1414. GRB 190114C light curves
- ID:
- ivo://CDS.VizieR/J/ApJ/892/97
- Title:
- GRB 190114C light curves
- Short Name:
- J/ApJ/892/97
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report multicolor optical imaging and polarimetry observations of the afterglow of the first TeV-detected gamma-ray burst (GRB), GRB 190114C, using the RINGO3 and MASTER II polarimeters. Observations begin 31s after the onset of the GRB and continue until ~7000s postburst. The light curves reveal a chromatic break at ~400-500s, with initial temporal decay {alpha}=1.669+/-0.013 flattening to {alpha}~1 postbreak, which we model as a combination of reverse and forward shock components with magnetization parameter R_B_~70. The observed polarization degree decreases from 7.7%+/-1.1% to 2%-4% 52-109s postburst and remains steady at this level for the subsequent ~2000s at a constant position angle. Broadband spectral energy distribution modeling of the afterglow confirms that GRB 190114C is highly obscured (A_v,HG_=1.49+/-0.12mag; N_H,HG_=(9.0+/-0.03)x10^22^cm^-2^). We interpret the measured afterglow polarization as intrinsically low and dominated by dust -in contrast to the P>10% measured previously for other GRB reverse shocks-with a small contribution from polarized prompt photons in the first minute. We test whether first- and higher-order inverse Compton scattering in a magnetized reverse shock can explain the low optical polarization and subteraelectronvolt emission but conclude that neither is explained in the reverse shock inverse Compton model. Instead, the unexpectedly low intrinsic polarization degree in GRB 190114C can be explained if large-scale jet magnetic fields are distorted on timescales prior to reverse shock emission.
- ID:
- ivo://CDS.VizieR/J/AJ/141/36
- Title:
- GRB 080607 multi-band light curves
- Short Name:
- J/AJ/141/36
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present early-time optical through infrared photometry of the bright Swift gamma-ray burst (GRB) 080607, starting only 6s following the initial trigger in the rest frame. Complemented by our previously published spectroscopy, this high-quality photometric data set allows us to solve for the extinction properties of the redshift 3.036 sightline, giving perhaps the most detailed information to date on the ultraviolet continuum absorption properties of any sightline outside our Local Group.
- ID:
- ivo://CDS.VizieR/J/ApJ/772/73
- Title:
- GRB with early-time optical emission
- Short Name:
- J/ApJ/772/73
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a multi-wavelength analysis of Swift gamma-ray burst GRB 090727, for which optical emission was detected during the prompt {gamma}-ray emission by the 2m autonomous robotic Liverpool Telescope and subsequently monitored for a further two days with the Liverpool and Faulkes Telescopes. Within the context of the standard fireball model, we rule out a reverse shock origin for the early-time optical emission in GRB 090727 and instead conclude that the early-time optical flash likely corresponds to emission from an internal dissipation process. Putting GRB 090727 into a broader observational and theoretical context, we build a sample of 36 {gamma}-ray bursts (GRBs) with contemporaneous early-time optical and {gamma}-ray detections. From these GRBs, we extract a sub-sample of 18 GRBs, which show optical peaks during prompt {gamma}-ray emission, and perform detailed temporal and spectral analysis in {gamma}-ray, X-ray, and optical bands. We find that in most cases early-time optical emission shows sharp and steep behavior, and notice a rich diversity of spectral properties. Using a simple internal shock dissipation model, we show that the emission during prompt GRB phase can occur at very different frequencies via synchrotron radiation. Based on the results obtained from observations and simulation, we conclude that the standard external shock interpretation for early-time optical emission is disfavored in most cases due to sharp peaks ({Delta}t/t<1) and steep rise/decay indices, and that internal dissipation can explain the properties of GRBs with optical peaks during {gamma}-ray emission.
- ID:
- ivo://CDS.VizieR/J/ApJ/770/95
- Title:
- g'RcIcJ photometry of the hot Uranus GJ3470b
- Short Name:
- J/ApJ/770/95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical (g', R_c_, and I_c_) to near-infrared (J) simultaneous photometric observations for a primary transit of GJ3470b, a Uranus-mass transiting planet around a nearby M dwarf, by using the 50cm MITSuME telescope and the 188cm telescope, both at the Okayama Astrophysical Observatory. From these data, we derive the planetary mass, radius, and density as 14.1 +/-1.3M_{Earth}_, 4.32_-0.10_^+0.21^R_{Earth}_, and 0.94+/-0.12g/cm3, respectively, thus confirming the low density that was reported by Demory et al. (2013ApJ...768..154D) based on the Spitzer/IRAC 4.5{mu}m photometry (0.72_-0.12_^+0.13^g/cm3). Although the planetary radius is about 10% smaller than that reported by Demory et al., this difference does not alter their conclusion that the planet possesses a hydrogen-rich envelope whose mass is approximately 10% of the planetary total mass. On the other hand, we find that the planet-to-star radius ratio (R_p_/R_s_) in the J band (0.07577_-0.00075_^+0.00072^) is smaller than that in the I_c_(0.0802+/-0.0013) and 4.5{mu}m (0.07806_-0.00054_^+0.00052^) bands by 5.8%+/-2.0% and 2.9%+/-1.1%, respectively. A plausible explanation for the differences is that the planetary atmospheric opacity varies with wavelength due to absorption and/or scattering by atmospheric molecules. Although the significance of the observed R_p_/R_s_variations is low, if confirmed, this fact would suggest that GJ3470b does not have a thick cloud layer in the atmosphere. This property would offer a wealth of opportunity for future transmission-spectroscopic observations of this planet to search for certain molecular features, such as H_2_O, CH_4_, and CO, without being prevented by clouds.
- ID:
- ivo://CDS.VizieR/J/A+A/536/A89
- Title:
- g'r'i' and redshift of Abell 2254 galaxies
- Short Name:
- J/A+A/536/A89
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The mechanisms giving rise to diffuse radio emission in galaxy clusters and, in particular, their connection with cluster mergers are still being debated. We explore the internal dynamics of Abell 2254, which has been shown to host a very clumpy and irregular radio halo. Our analysis is mainly based on redshift data for 128 galaxies acquired at the Telescopio Nazionale Galileo. We combined galaxy velocities and positions to select 110 cluster galaxies and analyze its internal dynamics. We also used new (g', r', i') photometric data acquired at the Isaac Newton Telescope, and (V, i') photometric data available in the Subaru Archive. X-ray data from the XMM-Newton Science Archive were analyzed to study the hot gas component.
- ID:
- ivo://CDS.VizieR/J/AJ/160/277
- Title:
- gri-light curve of near-Earth asteroid 2020 CD3
- Short Name:
- J/AJ/160/277
- Date:
- 08 Dec 2021
- Publisher:
- CDS
- Description:
- We report on our detailed characterization of Earth's second known temporary natural satellite, or minimoon, asteroid 2020CD3. An artificial origin can be ruled out based on its area-to-mass ratio and broadband photometry, which suggest that it is a silicate asteroid belonging to the S or V complex in asteroid taxonomy. The discovery of 2020CD3 allows for the first time a comparison between known minimoons and theoretical models of their expected physical and dynamical properties. The estimated diameter of 1.2_-0.2_^+0.4^m and geocentric capture approximately a decade after the first known minimoon, 2006RH120, are in agreement with theoretical predictions. The capture duration of 2020CD3 of at least 2.7yr is unexpectedly long compared to the simulation average, but it is in agreement with simulated minimoons that have close lunar encounters, providing additional support for the orbital models. 2020CD3's atypical rotation period, significantly longer than theoretical predictions, suggests that our understanding of meter-scale asteroids needs revision. More discoveries and a detailed characterization of the population can be expected with the forthcoming Vera C. Rubin Observatory Legacy Survey of Space and Time.
- ID:
- ivo://CDS.VizieR/J/ApJ/756/73
- Title:
- gri light curves of the low-luminosity AGN NGC 4395
- Short Name:
- J/ApJ/756/73
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of broadband photometric reverberation mapping (RM) to measure the radius of the broad-line region, and subsequently the black hole mass (M_BH_), in the nearby, low-luminosity active galactic nuclei NGC 4395. Using the Wise Observatory's 1m telescope equipped with the Sloan Digital Sky Survey g', r', and i' broadband filters, we monitored NGC 4395 for nine consecutive nights and obtained three light curves each with over 250 data points. The g' and r' bands include time variable contributions from H{beta} and H{alpha}, respectively, plus continuum. The i' band is free of broad lines and covers exclusively continuum. We show that by looking for a peak in the difference between the cross-correlation and the auto-correlation functions for all combinations of filters, we can get a reliable estimate of the time lag necessary to compute M_BH_. We measure the time lag for H{alpha} to be 3.6+/-0.8hr, comparable to previous studies using the line-resolved spectroscopic RM method. We argue that this lag implies a black hole mass of M_BH_=(4.9+/-2.6)x10^4^M_{sun}_.
