scholarly journals Searching for electromagnetic counterparts to gravitational-wave merger events with the prototype Gravitational-Wave Optical Transient Observer (GOTO-4)

2020 ◽  
Vol 497 (1) ◽  
pp. 726-738 ◽  
Author(s):  
B P Gompertz ◽  
R Cutter ◽  
D Steeghs ◽  
D K Galloway ◽  
J Lyman ◽  
...  
Keyword(s):  
Gravitational Wave ◽  
Gamma Ray ◽  
Source Region ◽  
Binary Neutron Star ◽  
La Palma ◽  
Binary Black Hole ◽  
Test Models ◽  
Localization Performance ◽  
Optical Transient

ABSTRACT We report the results of optical follow-up observations of 29 gravitational-wave (GW) triggers during the first half of the LIGO–Virgo Collaboration (LVC) O3 run with the Gravitational-wave Optical Transient Observer (GOTO) in its prototype 4-telescope configuration (GOTO-4). While no viable electromagnetic (EM) counterpart candidate was identified, we estimate our 3D (volumetric) coverage using test light curves of on- and off-axis gamma-ray bursts and kilonovae. In cases where the source region was observable immediately, GOTO-4 was able to respond to a GW alert in less than a minute. The average time of first observation was 8.79 h after receiving an alert (9.90 h after trigger). A mean of 732.3 square degrees were tiled per event, representing on average 45.3 per cent of the LVC probability map, or 70.3 per cent of the observable probability. This coverage will further improve as the facility scales up alongside the localization performance of the evolving GW detector network. Even in its 4-telescope prototype configuration, GOTO is capable of detecting AT2017gfo-like kilonovae beyond 200 Mpc in favourable observing conditions. We cannot currently place meaningful EM limits on the population of distant ($\hat{D}_L = 1.3$ Gpc) binary black hole mergers because our test models are too faint to recover at this distance. However, as GOTO is upgraded towards its full 32-telescope, 2 node (La Palma & Australia) configuration, it is expected to be sufficiently sensitive to cover the predicted O4 binary neutron star merger volume, and will be able to respond to both northern and southern triggers.

scholarly journals Searching for Fermi GRB optical counterparts with the prototype Gravitational-wave Optical Transient Observer (GOTO)

2021 ◽  
Vol 507 (4) ◽  
pp. 5463-5476
Author(s):  
Y-L Mong ◽  
K Ackley ◽  
D K Galloway ◽  
M Dyer ◽  
R Cutter ◽  
...  
Keyword(s):  
Gravitational Wave ◽  
Gamma Ray ◽  
Rapid Identification ◽  
Large Field ◽  
Gamma Ray Burst ◽  
La Palma ◽  
Multiple Observations ◽  
Overall Performance ◽  
Optical Transient

ABSTRACT The typical detection rate of ∼1 gamma-ray burst (GRB) per day by the Fermi Gamma-ray Burst Monitor (GBM) provides a valuable opportunity to further our understanding of GRB physics. However, the large uncertainty of the Fermi localization typically prevents rapid identification of multiwavelength counterparts. We report the follow-up of 93 Fermi GRBs with the Gravitational-wave Optical Transient Observer (GOTO) prototype on La Palma. We selected 53 events (based on favourable observing conditions) for detailed analysis, and to demonstrate our strategy of searching for optical counterparts. We apply a filtering process consisting of both automated and manual steps to 60 085 candidates initially, rejecting all but 29, arising from 15 events. With ≈3 GRB afterglows expected to be detectable with GOTO from our sample, most of the candidates are unlikely to be related to the GRBs. Since we did not have multiple observations for those candidates, we cannot confidently confirm the association between the transients and the GRBs. Our results show that GOTO can effectively search for GRB optical counterparts thanks to its large field of view of ≈40 deg2 and its depth of ≈20 mag. We also detail several methods to improve our overall performance for future follow-up programmes of Fermi GRBs.

scholarly journals Towards Improving the Prospects for Coordinated Gravitational-Wave and Electromagnetic Observations

2011 ◽  
Vol 7 (S285) ◽  
pp. 358-360 ◽  
Author(s):  
Ilya Mandel ◽  
Luke Z. Kelley ◽  
Enrico Ramirez-Ruiz
Keyword(s):  
Gravitational Wave ◽  
Prior Information ◽  
Gamma Ray ◽  
Optimal Parameter ◽  
Gamma Ray Bursts ◽  
Binary Neutron Star ◽  
Quantitative Estimates ◽  
Optimal Parameter Estimation ◽  
Parameter Estimation Techniques

AbstractWe discuss two approaches to searches for gravitational-wave (GW) and electromagnetic (EM) counterparts of binary neutron-star mergers. The first approach relies on triggering archival searches of GW detector data based on detections of EM transients. Quantitative estimates of the improvement to GW detector reach due to the increased confidence in the presence and parameters of a signal from a binary merger gained from the EM transient suggest utilizing other transients in addition to short gamma-ray bursts. The second approach involves following up GW candidates with targeted EM observations. We argue for the use of slower but optimal parameter-estimation techniques and for a more sophisticated use of astrophysical prior information, including galaxy catalogues to find preferred follow-up locations.

scholarly journals Data-driven Expectations for Electromagnetic Counterpart Searches Based on LIGO/Virgo Public Alerts

2022 ◽  
Vol 924 (2) ◽  
pp. 54
Author(s):  
Polina Petrov ◽  
Leo P. Singer ◽  
Michael W. Coughlin ◽  
Vishwesh Kumar ◽  
Mouza Almualla ◽  
...  
Keyword(s):  
Data Analysis ◽  
Neutron Star ◽  
Gravitational Wave ◽  
Gamma Ray ◽  
Data Driven ◽  
Wave Localization ◽  
Localization Accuracy ◽  
Binary Neutron Star ◽  
Data Release

Abstract Searches for electromagnetic counterparts of gravitational-wave signals have redoubled since the first detection in 2017 of a binary neutron star merger with a gamma-ray burst, optical/infrared kilonova, and panchromatic afterglow. Yet, one LIGO/Virgo observing run later, there has not yet been a second, secure identification of an electromagnetic counterpart. This is not surprising given that the localization uncertainties of events in LIGO and Virgo’s third observing run, O3, were much larger than predicted. We explain this by showing that improvements in data analysis that now allow LIGO/Virgo to detect weaker and hence more poorly localized events have increased the overall number of detections, of which well-localized, gold-plated events make up a smaller proportion overall. We present simulations of the next two LIGO/Virgo/KAGRA observing runs, O4 and O5, that are grounded in the statistics of O3 public alerts. To illustrate the significant impact that the updated predictions can have, we study the follow-up strategy for the Zwicky Transient Facility. Realistic and timely forecasting of gravitational-wave localization accuracy is paramount given the large commitments of telescope time and the need to prioritize which events are followed up. We include a data release of our simulated localizations as a public proposal planning resource for astronomers.

scholarly journals Could GRB170817A be really correlated to an NS–NS merging?

2018 ◽  
Vol 27 (06) ◽  
pp. 1841001 ◽  
Author(s):  
D. Fargion ◽  
M. Yu. Khlopov ◽  
P. Oliva
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Gamma Ray ◽  
Solid Angle ◽  
Open Disk ◽  
Binary Neutron Star ◽  
Binary Black Hole ◽  
Exciting Development ◽  
Soft Disk ◽  
Optical Transient

The exciting development of gravitational wave (GW) astronomy in the correlation of LIGO and VIRGO detection of GW signals makes possible to expect registration of effects of not only binary black hole (BH) coalescence but also binary neutron star (NS) merging accompanied by electromagnetic (gamma ray burst; GRB) signal. Here we consider the possibility that an NS, merging in an NS–NS or NS–BH system might be (soon) observed in correlation with any LIGO–VIRGO GWs detection. We analyze as an example the recent case of the short GRB170817A observed by Fermi and integral. The associated optical transient (OT) source in NGC4993 implies a rare near source, a consequent averaged large rate of such events (almost) compatible with expected NS–NS merging rate. However the expected beamed GRB (or short GRB) may be mostly aligned to a different direction than ours. Therefore, even soft GRB photons, spread more than hard ones, might be hardly able to shower to us. Nevertheless, a prompt spiraling electron turbine jet in largest magnetic fields, at the base of the NS–NS collapse, might shine by its tangential synchrotron radiation in spread way with its skimming photons shining in large open disk. The consequent solid angle for such soft disk gamma radiation may be large enough to be nevertheless often observed.

scholarly journals Swift-XRT follow-up of gravitational wave triggers during the third aLIGO/Virgo observing run

2020 ◽  
Vol 499 (3) ◽  
pp. 3459-3480
Author(s):  
K L Page ◽  
P A Evans ◽  
A Tohuvavohu ◽  
J A Kennea ◽  
N J Klingler ◽  
...  
Keyword(s):  
Gravitational Wave ◽  
X Ray ◽  
Binary Neutron Star ◽  
The Third ◽  
Mass Gap ◽  
Binary Black Hole ◽  
Sky Survey ◽  
Upper Limits ◽  
Transient Sources

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 × 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.

scholarly journals The first six months of the Advanced LIGO’s and Advanced Virgo’s third observing run with GRANDMA

2019 ◽  
Vol 492 (3) ◽  
pp. 3904-3927 ◽  
Author(s):  
S Antier ◽  
S Agayeva ◽  
V Aivazyan ◽  
S Alishov ◽  
E Arbouch ◽  
...  
Keyword(s):  
Neutron Star ◽  
Gravitational Wave ◽  
Gamma Ray ◽  
Spatial Localization ◽  
Gamma Ray Bursts ◽  
Binary Neutron Star ◽  
The Third ◽  
Transient Events ◽  
Tools And Methods

ABSTRACT We present the Global Rapid Advanced Network Devoted to the Multi-messenger Addicts (GRANDMA). The network consists of 21 telescopes with both photometric and spectroscopic facilities. They are connected together thanks to a dedicated infrastructure. The network aims at coordinating the observations of large sky position estimates of transient events to enhance their follow-up and reduce the delay between the initial detection and optical confirmation. The GRANDMA programme mainly focuses on follow-up of gravitational-wave alerts to find and characterize the electromagnetic counterpart during the third observational campaign of the Advanced LIGO and Advanced Virgo detectors. But it allows for follow-up of any transient alerts involving neutrinos or gamma-ray bursts, even those with poor spatial localization. We present the different facilities, tools, and methods we developed for this network and show its efficiency using observations of LIGO/Virgo S190425z, a binary neutron star merger candidate. We furthermore report on all GRANDMA follow-up observations performed during the first six months of the LIGO–Virgo observational campaign, and we derive constraints on the kilonova properties assuming that the events’ locations were imaged by our telescopes.

scholarly journals Gravitational waves from mountains in newly born millisecond magnetars

2021 ◽  
Vol 502 (4) ◽  
pp. 4680-4688
Author(s):  
Ankan Sur ◽  
Brynmor Haskell
Keyword(s):  
Gravitational Wave ◽  
Gravitational Waves ◽  
Massive Star ◽  
Gamma Ray ◽  
Dipole Radiation ◽  
X Ray ◽  
Binary Neutron Star ◽  
Spin Period ◽  
Lower Maximum ◽  
Wave Emission

ABSTRACT In this paper, we study the spin-evolution and gravitational-wave luminosity of a newly born millisecond magnetar, formed either after the collapse of a massive star or after the merger of two neutron stars. In both cases, we consider the effect of fallback accretion; and consider the evolution of the system due to the different torques acting on the star, namely the spin-up torque due to accretion and spin-down torques due to magnetic dipole radiation, neutrino emission, and gravitational-wave emission linked to the formation of a ‘mountain’ on the accretion poles. Initially, the spin period is mostly affected by the dipole radiation, but at later times, accretion spin the star up rapidly. We find that a magnetar formed after the collapse of a massive star can accrete up to 1 M⊙, and survive on the order of 50 s before collapsing to a black hole. The gravitational-wave strain, for an object located at 1 Mpc, is hc ∼ 10−23 at kHz frequencies, making this a potential target for next-generation ground-based detectors. A magnetar formed after a binary neutron star merger, on the other hand, accretes at the most 0.2 M⊙ and emits gravitational waves with a lower maximum strain of the order of hc ∼ 10−24, but also survives for much longer times, and may possibly be associated with the X-ray plateau observed in the light curve of a number of short gamma-ray burst.

scholarly journals Tests of weak equivalence principle with the gravitational wave signals in the LIGO–Virgo catalogue GWTC-1

2020 ◽  
Vol 499 (1) ◽  
pp. L53-L57
Author(s):  
Shu-Cheng Yang ◽  
Wen-Biao Han ◽  
Gang Wang
Keyword(s):  
Gravitational Wave ◽  
Equivalence Principle ◽  
Arrival Time ◽  
Gamma Ray ◽  
Weak Equivalence ◽  
Radio Bursts ◽  
Weak Equivalence Principle ◽  
Massive Galaxies ◽  
Binary Black Hole ◽  
Gravitational Theories

ABSTRACT The weak equivalence principle (WEP) is the cornerstone of gravitational theories. At the local scale, WEP has been tested to high accuracy by various experiments. On the intergalactic distance scale, WEP could be tested by comparing the arrival time of different messengers emitted from the same source. The gravitational time delay caused by massive galaxies is proportional to γ + 1, where the parameter γ is unity in general relativity. The values of γ for different massless particles should be different if WEP is violated, i.e. Δγ is used to indicate the deviation from WEP. So far, |Δγ| has been constrained with gamma-ray bursts, fast radio bursts, etc. Here, we report a new constraint of |Δγ| by using the gravitational wave data of binary black hole coalescences in the LIGO–Virgo catalogue GWTC-1. The best constraints imply that |Δγ| ≲ 10−15 at 90 per cent confidence level.

scholarly journals MAGIC electromagnetic follow-up of gravitational wave alerts

2016 ◽  
Vol 12 (S324) ◽  
pp. 287-290
Author(s):  
Barbara De Lotto ◽  
Stefano Ansoldi ◽  
Angelo Antonelli ◽  
Alessio Berti ◽  
Alessandro Carosi ◽  
...  
Keyword(s):  
Black Hole ◽  
Data Analysis ◽  
Gravitational Wave ◽  
Laser Interferometer ◽  
Cherenkov Telescopes ◽  
Direct Observations ◽  
Binary Black Hole ◽  
Set Up

AbstractThe year 2015 witnessed the first direct observations of a transient gravitational-wave (GW) signal from binary black hole mergers by the Advanced Laser Interferometer Gravitational-wave Observatory (aLIGO) Collaboration with the Virgo Collaboration. The MAGIC two 17m diameter Cherenkov telescopes system joined since 2014 the vast collaboration of electromagnetic facilities for follow-up of gravitational wave alerts. During the 2015 LIGO-Virgo science run we set up the procedure for GW alerts follow-up and took data following the last GW alert. MAGIC results on the data analysis and prospects for the forthcoming run are presented.

scholarly journals Constraints on the circumburst environments of short gamma-ray bursts

2020 ◽  
Vol 495 (4) ◽  
pp. 4782-4799 ◽  
Author(s):  
Brendan O’Connor ◽  
Paz Beniamini ◽  
Chryssa Kouveliotou
Keyword(s):  
Gamma Ray ◽  
Galactic Halo ◽  
Gamma Ray Bursts ◽  
Light Curves ◽  
Host Galaxy ◽  
Host Galaxies ◽  
Binary Neutron Star ◽  
Range Of Values ◽  
Short Grbs

ABSTRACT Observational follow up of well localized short gamma-ray bursts (SGRBs) has left $20\!-\!30{{\ \rm per\ cent}}$ of the population without a coincident host galaxy association to deep optical and NIR limits (≳26 mag). These SGRBs have been classified as observationally hostless due to their lack of strong host associations. It has been argued that these hostless SGRBs could be an indication of the large distances traversed by the binary neutron star system (due to natal kicks) between its formation and its merger (leading to an SGRB). The distances of GRBs from their host galaxies can be indirectly probed by the surrounding circumburst densities. We show that a lower limit on those densities can be obtained from early afterglow light curves. We find that ${\lesssim}16{{\ \rm per\ cent}}$ of short GRBs in our sample took place at densities ≲10−4 cm−3. These densities represent the expected range of values at distances greater than the host galaxy’s virial radii. We find that out of the five SGRBs in our sample that have been found to be observationally hostless, none are consistent with having occurred beyond the virial radius of their birth galaxies. This implies one of two scenarios. Either these observationally hostless SGRBs occurred outside of the half-light radius of their host galaxy, but well within the galactic halo, or in host galaxies at moderate to high redshifts (z ≳ 2) that were missed by follow-up observations.

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