LIGO/Virgo/KAGRA S240910ci
GCN Circular 37446
Subject
LIGO/Virgo/KAGRA S240910ci: Identification of a GW compact binary merger candidate
Date
2024-09-10T12:14:42Z (9 months ago)
From
Maria Lisa Brozzetti at Università degli Studi di Perugia <marialisa.brozzetti@ligo.org>
Via
Web form
The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report:
We identified the compact binary merger candidate S240910ci during real-time processing of data from LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) at 2024-09-10 10:35:35.495 UTC (GPS time: 1409999753.495). The candidate was found by the CWB [1], GstLAL [2], MBTA [3], and PyCBC Live [4] analysis pipelines.
S240910ci is an event of interest because its false alarm rate, as estimated by the online analysis, is 3.2e-10 Hz, or about one in 1e2 years. The event's properties can be found at this URL:
https://gracedb.ligo.org/superevents/S240910ci
The initial classification of the GW signal, based on chirp-mass information only [4], in order of descending probability, is BBH (69%), NSBH (31%), Terrestrial (<1%), or BNS (<1%). Preliminary information from parameter estimation seems to indicate a much smaller NSBH probability, and almost certainly a BBH origin.
Assuming the candidate is astrophysical in origin, the probability that the lighter compact object is consistent with a neutron star mass (HasNS) is <1%. [5] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [5] Both HasNS and HasRemnant consider the support of several neutron star equations of state. The probability that either of the binary components lies between 3 and 5 solar masses (HasMassGap) is 9%.
Two sky maps are available at this time and can be retrieved from the GraceDB event page:
* bayestar.multiorder.fits,0, an initial localization generated by BAYESTAR [6], distributed via GCN notice about 28 seconds after the candidate event time.
* bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [6], distributed via GCN notice about 5 minutes after the candidate event time.
The preferred sky map at this time is bayestar.multiorder.fits,1. For the bayestar.multiorder.fits,1 sky map, the 90% credible region is 370 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 641 +/- 169 Mpc (a posteriori mean +/- standard deviation).
For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/.
[1] Klimenko et al. PRD 93, 042004 (2016) doi:10.1103/PhysRevD.93.042004
[2] Tsukada et al. PRD 108, 043004 (2023) doi:10.1103/PhysRevD.108.043004 and Ewing et al. (2023) arXiv:2305.05625
[3] Aubin et al. CQG 38, 095004 (2021) doi:10.1088/1361-6382/abe913
[4] Dal Canton et al. ApJ 923, 254 (2021) doi:10.3847/1538-4357/ac2f9a
[5] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe
[6] Singer & Price PRD 93, 024013 (2016) doi:10.1103/PhysRevD.93.024013
GCN Circular 37447
Subject
LIGO/Virgo/KAGRA S240910ci: Updated Sky localization and EM Bright Classification
Date
2024-09-10T12:35:33Z (9 months ago)
From
Aaron Zimmerman at U. of Texas at Austin <aaron.zimmerman@utexas.edu>
Via
Web form
The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report:
We have conducted further analysis of the LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) data around the time of the compact binary merger (CBC) candidate S240910ci (GCN Circular 37446). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.multiorder.fits,0, distributed via GCN Notice, is available for retrieval from the GraceDB event page:
https://gracedb.ligo.org/superevents/S240910ci
Based on posterior support from parameter estimation [1], under the assumption that the candidate S240910ci is astrophysical in origin, the probability that the lighter compact object is consistent with a neutron star mass (HasNS) is <1%. [2] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [2] Both HasNS and HasRemnant consider the support of several neutron star equations of state. The probability that either of the binary components lies between 3 and 5 solar masses (HasMassGap) is 5%.
For the Bilby.multiorder.fits,0 sky map, the 90% credible region is 394 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 662 +/- 166 Mpc (a posteriori mean +/- standard deviation).
For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/.
[1] Ashton et al. ApJS 241, 27 (2019) doi:10.3847/1538-4365/ab06fc and Morisaki et al. (2023) arXiv:2307.13380
[2] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe
GCN Circular 37448
Subject
LIGO/Virgo/KAGRA S240910ci: Coverage and upper limits from MAXI/GSC observations
Date
2024-09-10T13:06:47Z (9 months ago)
From
Yuta Kawakubo at Aoyama Gakuin University <kawakubo@phys.aoyama.ac.jp>
Via
Web form
H. Hiramatsu, S. Sugita, M. Serino, Y. Kawakubo, H. Nishikawa, Y. Kondo (AGU)
H. Negoro, M. Nakajima, K. Takagi (Nihon U.),
N. Kawai, T. Mihara, (RIKEN),
report on behalf of the MAXI team:
We examined MAXI/GSC all-sky X-ray images (2-20 keV)
after compact binary merger candidate S240910ci at 2024-09-10 10:35:35.495 UTC (GCN #37446, 37447).
At the trigger time of S240910ci, the high-voltage of MAXI/GSC was on.
The instantaneous field of view of GSC at the GW trigger time covered 6% of the 90% credible region
of the Bilby sky map, in which we found no significant new X-ray source.
The first one-orbit (92 min) scan observation with GSC after the event covered 51%
of the 90% credible region of the Bilby skymap from 10:35:35 to 10:45:20 UTC (T0+0 to T0+585 sec).
No significant new source was found in the region in the one-orbit scan observation.
A typical 1-sigma averaged upper limit obtained in one scan observation
is 20 mCrab at 2-20 keV.
If you require information about X-ray flux by MAXI/GSC at specific coordinates,
please contact the submitter of this circular by email.
GCN Circular 37451
Subject
LIGO/Virgo/KAGRA S240910ci: NED Galaxies in the Localization Volume
Date
2024-09-10T15:46:32Z (9 months ago)
From
David Cook at Caltech/IPAC-NED <dcook@ipac.caltech.edu>
Via
Web form
David O. Cook (Caltech/IPAC), Rick Ebert (Caltech/IPAC), George Helou (Caltech/IPAC), Joseph M. Mazzarella (Caltech/IPAC), Marion Schmitz (Caltech/IPAC), and Leo Singer (NASA/GSFC)
On behalf of the NASA/IPAC Extragalactic Database (NED) Team.
We spatially cross-matched the LVK S240910ci-4-Update sky localization with the NED Local Volume Sample (NED-LVS; Cook et al. 2023), which is a subset of NED with a redshift or redshift-independent distance less than 1000 Mpc. We find 21074 galaxies within the 90% containment volume, and we list here the top 20 galaxies located in the 90% volume sorted by the joint probability of the 3D localization and the WISE W1 luminosity (an observable proxy for stellar mass). For the full list of galaxies in the 90% volume go to the NED Gravitational Wave Followup service at https://ned.ipac.caltech.edu/uri/NED::GWF/.
The NED-GWF service provides downloadable galaxy lists and visualizations for candidate host galaxies. For each GW alert, these products are automatically generated and made available within minutes to expedite efficient electromagnetic followup observations. The NED top 20 list is sorted by the joint probability of the 3D localization and the WISE W1 luminosity, but users can sort on additional pre-computed prioritization metrics (star formation rate, P_3D*P_SFR; and specific star formation rate, P_3D*P_sSFR; etc.) which are available via downloading the entire galaxy list inside the event's probability volume (https://ned.ipac.caltech.edu/uri/NED::GWFglist/fits/S240910ci/4).
The NED-GWF service provides downloadable galaxy lists and visualizations for candidate host galaxies. For each GW alert, these products are automatically generated and made available within minutes to expedite efficient electromagnetic followup observations. The NED top 20 list is sorted by the joint probability of the 3D localization and the WISE W1 luminosity, but users can sort on additional pre-computed prioritization metrics (star formation rate, P_3D*P_SFR; and specific star formation rate, P_3D*P_sSFR; etc.) which are available via downloading the entire galaxy list inside the event's probability volume.
| objname| ra| dec|objtype| DistMpc|DistMpc_unc| m_NUV| m_NUV_unc| m_Ks| m_Ks_unc| m_W1| m_W1_unc| P_3D|P_3D_LumW1|
|-------------------------|--------------|--------------|-------|-----------|-----------|------------|------------|------------|------------|------------|------------|--------|----------|
| | deg| deg| | Mpc| | mag(AB)| | mag| | mag| | Prob| Prob|
|WISEA J164409.31-231729.3| 251.03900| -23.29122| G| 749.57| null| null| null| 13.758| 0.234| 9.619| 0.006|1.83e-07| 8.27e-10|
|WISEA J163915.56-213504.9| 249.81471| -21.58469| G| 709.57| null| null| null| 13.096| 0.159| 9.098| 0.006|9.01e-08| 6.05e-10|
|WISEA J163638.27-214542.4| 249.15938| -21.76197| G| 567.91| null| null| null| 12.632| 0.136| 9.280| 0.006|1.36e-07| 4.99e-10|
|WISEA J153550.65-035805.5| 233.96117| -3.96828| G| 663.16| null| null| null| 13.466| 0.191| 10.156| 0.006|1.02e-07| 2.10e-10|
|WISEA J162900.97-210059.6| 247.25408| -21.01647| G| 573.91| null| null| null| 13.818| 0.228| 10.467| 0.006|1.30e-07| 1.61e-10|
|WISEA J152149.85+035149.1| 230.45765| 3.86368| G| 623.56| 0.17| null| null| 13.363| 0.177| 9.104| 0.005|3.34e-08| 1.56e-10|
|WISEA J152447.08+020820.1| 231.19621| 2.13875| G| 601.36| 0.10| null| null| 13.781| 0.204| 9.912| 0.006|7.23e-08| 1.50e-10|
|WISEA J183519.73-344943.1| 278.83229| -34.82897| G| 508.12| 0.65| null| null| 13.055| 0.175| 8.734| 0.006|3.17e-08| 1.39e-10|
|WISEA J011220.13+774357.3| 18.08408| 77.73272| G| 610.93| null| null| null| 13.436| 0.148| 9.155| 0.005|2.83e-08| 1.26e-10|
|WISEA J155309.64-100115.7| 238.29025| -10.02103| G| 595.95| null| null| null| 13.502| 0.184| 10.902| 0.006|1.50e-07| 1.26e-10|
|WISEA J183650.82-343757.6| 279.21167| -34.63275| G| 556.83| null| null| null| 13.146| 0.176| 8.992| 0.006|2.89e-08| 1.20e-10|
|WISEA J165512.10-252007.7| 253.80054| -25.33542| G| 743.05| null| null| null| 13.702| 0.238| 11.493| 0.021|1.43e-07| 1.10e-10|
|WISEA J165757.99-252522.8| 254.49162| -25.42308| G| 695.19| null| null| null| 13.220| 0.166| 11.303| 0.010|1.38e-07| 1.10e-10|
|WISEA J152539.59+014654.8| 231.41497| 1.78186| G| 588.73| 0.21| null| null| 13.291| 0.170| 10.152| 0.006|6.60e-08| 1.05e-10|
|WISEA J160123.53-140150.0| 240.34808| -14.03058| G| 688.38| null| null| null| 13.187| 0.173| 11.878| 0.009|2.12e-07| 9.62e-11|
|WISEA J145024.06+173433.1| 222.60029| 17.57597| G| 560.68| 0.11| null| null| 12.972| 0.035| 9.001| 0.005|2.31e-08| 9.57e-11|
|WISEA J165558.47-253042.2| 253.99354| -25.51117| G| 749.48| null| null| null| 13.738| 0.313| 11.733| 0.035|1.42e-07| 8.87e-11|
|WISEA J154022.30-063237.4| 235.09296| -6.54372| G| 622.65| null| 21.550| 0.323| 13.411| 0.171| 11.231| 0.007|1.24e-07| 8.30e-11|
|WISEA J154810.27-092639.1| 237.04271| -9.44422| G| 511.44| null| null| null| 13.468| 0.187| 10.701| 0.006|9.32e-08| 6.88e-11|
|WISEA J151611.06-001945.6| 229.04623| -0.32940| G| 565.66| 0.53| null| null| 13.192| 0.054| 9.570| 0.006|2.61e-08| 6.54e-11|
Table 1: Top 20 galaxies in NED-LVS that fall in the 90% probability volume for S240910ci sorted by the joint probability of 3D position and WISE W1 luminosity (P_3D*P_LumW1). Galaxy is the NED preferred name. RA and Dec are the Equatorial coordinates in degrees (J2000). Objtype is the object type of the galaxy candidate. Distance is the distance to the galaxy in Mpc. m_NUV and mErr_NUV are the apparent magnitude and error from GALEX. m_Ks and mErr_Ks are the apparent magnitude and error from 2MASS. m_W1 and mErr_W1 are the apparent magnitude and error from AllWISE. P_3D is the probability that the galaxy is in the volume given the distance of GW event. P_3D_LumW1 is the joint probability within the volume weighted by the WISE1 luminosity of the galaxy (P_3D * P_LumW1).