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Register a new userINTEGRAL observations of GW170104
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Added by
Volodymyr Savchenko
Publication date
2017
fields
Physics
and research's language is
English
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We used data from the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) to set upper-limits on the ${gamma}$-ray and hard X-ray prompt emission associated with the gravitational wave event GW170104, discovered by the LIGO/Virgo collaboration. The unique omni-directional viewing capability of the instruments on-board INTEGRAL allowed us to examine the full 90% confidence level localization region of the LIGO trigger. Depending on the particular spectral model assumed and the specific position within this region, the upper limits inferred from the INTEGRAL observations range from F${gamma}$=1.9x10-7 erg cm-2 to F${gamma}$=10-6 erg cm-2 (75 keV - 2 MeV energy range). This translates into a ratio between the prompt energy released in ${gamma}$-rays along the direction to the observer and the gravitational wave energy of E${gamma}$/EGW <2.6x10-5 . Using the INTEGRAL results, we can not confirm the ${gamma}$-ray proposed counterpart to GW170104 by the AGILE team with the MCAL instrument. The reported flux of the AGILE/MCAL event, E2, is not compatible with the INTEGRAL upper limits within most of the 90% LIGO localization region. There is only a relatively limited portion of the sky where the sensitivity of the INTEGRAL instruments was not optimal and the lowest allowed fluence estimated for E2 would still be compatible with the INTEGRAL results. This region was also observed independently by Fermi/GBM and AstroSAT, from which, as far as we are aware, there are no reports of any significant detection of a prompt high-energy event.
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We present the emph{Fermi} Gamma-ray Burst Monitor (GBM) and Large Area Telescope (LAT) observations of the LIGO binary black hole merger (BBH) event GW170104. No candidate electromagnetic counterparts was detected by either GBM or LAT. A detailed analysis of the GBM and LAT data over timescales from seconds to days covering the LIGO localization region is presented. The resulting flux upper bound from the GBM is (5.2--9.4)$times$10$^{-7}$ erg cm$^{-2}$ s$^{-1}$ in the 10-1000 keV range and from the LAT is (0.2--13)$times$10$^{-9}$ erg cm$^{-2}$ s$^{-1}$ in the 0.1--1 GeV range. We also describe the improvements to our automated pipelines and analysis techniques for searching for and characterizing the potential electromagnetic counterparts for future gravitational wave events from Advanced LIGO/VIRGO.
The LIGO/Virgo Collaboration (LVC) detected on 2017 January 4, a significant gravitational-wave (GW) event (now named GW170104). We report in this Letter the main results obtained from the analysis of hard X-ray and gamma-ray data of the AGILE mission that repeatedly observed the GW170104 localization region (LR). At the LVC detection time $T_0$ AGILE observed about 36% of the LR. The gamma-ray imaging detector did not reveal any significant emission in the energy range 50 MeV--30 GeV. Furthermore, no significant gamma-ray transients were detected in the LR that was repeatedly exposed over timescales of minutes, hours, and days. We also searched for transient emission using data near $T_0$ of the omnidirectional detector MCAL operating in the energy band 0.4--100 MeV. A refined analysis of MCAL data shows the existence of a weak event (that we call E2) with a signal-to-noise ratio of $4.4,sigma$ lasting about 32 ms and occurring $0.46,pm,0.05 ,rm s$ before $T_0$. A study of the MCAL background and of the false-alarm rate of E2 leads to the determinination of a post-trial significance between $2.4,sigma$ and $2.7,sigma$ for a temporal coincidence with GW170104. We note that E2 has characteristics similar to those detected from the weak precursor of the short GRB 090510. The candidate event E2 is worth consideration for simultaneous detection by other satellites. If associated with GW170104, it shows emission in the MeV band of a short burst preceding the final coalescence by 0.46 sec and involving $sim 10^{-7}$ of the total rest mass energy of the system.
We report the discovery and multi-wavelength data analysis of the peculiar optical transient, ATLAS17aeu. This transient was identified in the skymap of the LIGO gravitational wave event GW170104 by our ATLAS and Pan-STARRS coverage. ATLAS17aeu was discovered 23.1hrs after GW170104 and rapidly faded over the next 3 nights, with a spectrum revealing a blue featureless continuum. The transient was also detected as a fading x-ray source by Swift and in the radio at 6 and 15 GHz. A gamma ray burst GRB170105A was detected by 3 satellites 19.04hrs after GW170104 and 4.10hrs before our first optical detection. We analyse the multi-wavelength fluxes in the context of the known GRB population and discuss the observed sky rates of GRBs and their afterglows. We find it statistically likely that ATLAS17aeu is an afterglow associated with GRB170105A, with a chance coincidence ruled out at the 99% confidence or 2.6$sigma$. A long, soft GRB within a redshift range of $1 lesssim z lesssim 2.9$ would be consistent with all the observed multi-wavelength data. The Poisson probability of a chance occurrence of GW170104 and ATLAS17aeu is $p=0.04$. This is the probability of a chance coincidence in 2D sky location and in time. These observations indicate that ATLAS17aeu is plausibly a normal GRB afterglow at significantly higher redshift than the distance constraint for GW170104 and therefore a chance coincidence. However if a redshift of the faint host were to place it within the GW170104 distance range, then physical association with GW170104 should be considered.
SN2011fe was detected by the Palomar Transient Factory on August 24th 2011 in M101 few hours after the explosion. From the early spectra it was immediately realized that it was a Type Ia supernova thus making this event the brightest one discovered in the last twenty years. In this paper the observations performed with the instruments on board of INTEGRAL (SPI, IBIS/ISGRI, JEM-X and OMC) before and after the maximum of the optical light as well as the interpretation in terms of the existing models of $gamma$--ray emission from such kind of supernovae are reported. All INTEGRAL high-energy have only been able to provide upper limits to the expected emission due to the decay of $^{56}$Ni. These bounds allow to reject explosions involving a massive white dwarf in the sub--Chandrasekhar scenario. On the other hand, the optical light curve obtained with the OMC camera suggests that the event was produced by a delayed detonation of a CO white dwarf that produced $sim 0.5$ M$odot$ of $^{56}$Ni. In this particular case, INTEGRAL would have only been able to detect the early $gamma$--ray emission if the supernova had occurred at a distance of 2 -3 Mpc, although the brightest event could be visible up to distances larger by a factor two.
We present multi-wavelength follow-up campaigns by the AstroSat-CZTI and GROWTH collaborations to search for an electromagnetic counterpart to the gravitational wave event GW170104. At the time of the GW170104 trigger, the AstroSat CZTI field-of-view covered 50.3% of the sky localization. We do not detect any hard X-ray (>100 keV) signal at this time, and place an upper limit of $approx 4.5 times 10^{-7}~{rm erg~cm}^{-2}{rm~s}^{-1}$ for a 1,s timescale. Separately, the ATLAS survey reported a rapidly fading optical source dubbed ATLAS17aeu in the error circle of GW170104. Our panchromatic investigation of ATLAS17aeu shows that it is the afterglow of an unrelated long, soft GRB~170105A, with only a fortuitous spatial coincidence with GW170104. We then discuss the properties of this transient in the context of standard long GRB afterglow models.
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