LIGO/Virgo/KAGRA S240925n
GCN Circular 37604
Subject
LIGO/Virgo/KAGRA S240925n: Identification of a GW compact binary merger candidate
Date
2024-09-25T01:53:06Z (8 months ago)
From
Chia-Hsuan Hsiung <sw56540@gmail.com>
Via
Web form
The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report:
We identified the compact binary merger candidate S240925n during real-time processing of data from LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) at 2024-09-25 00:58:09.990 UTC (GPS time: 1411261107.990). The candidate was found by the cWB [1], cWB BBH [2], GstLAL [3], MBTA [4], and SPIIR [5] analysis pipelines.
S240925n is an event of interest because its false alarm rate, as estimated by the online analysis, is 4e-20 Hz, or about one in 1e12 years. The event's properties can be found at this URL:
https://gracedb.ligo.org/superevents/S240925n
The classification of the GW signal, in order of descending probability, is BBH (>99%), BNS (<1%), NSBH (<1%), or Terrestrial (<1%).
Assuming the candidate is astrophysical in origin, the probability that the lighter compact object is consistent with a neutron star mass (HasNS) is <1%. [6] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [6] Both HasNS and HasRemnant consider the support of several neutron star equations of state for maximum neutron star mass. The probability that either of the binary components lies between 3 and 5 solar masses (HasMassGap) is 26%.
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 [7], distributed via GCN notice about 30 seconds after the candidate event time.
* bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [7], 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 40 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 329 +/- 76 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] T. Mishra et al. PRD 105, 083018 (2022) doi:10.1103/PhysRevD.105.083018
[3] Tsukada et al. PRD 108, 043004 (2023) doi:10.1103/PhysRevD.108.043004 and Ewing et al. (2023) arXiv:2305.05625
[4] Aubin et al. CQG 38, 095004 (2021) doi:10.1088/1361-6382/abe913
[5] Chu et al. PRD 105, 024023 (2022) doi:10.1103/PhysRevD.105.024023
[6] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe
[7] Singer & Price PRD 93, 024013 (2016) doi:10.1103/PhysRevD.93.024013
GCN Circular 37607
Subject
LIGO/Virgo/KAGRA S240925n: Updated Sky localization and Source Classification
Date
2024-09-25T07:41:06Z (8 months ago)
From
Colm Talbot at University of Chicago <talbotcolm@gmail.com>
Via
Web form
The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report:
We have identified a problem in the calibration of the LIGO Hanford instrument at the time of S240925n (GCN Circular 37604). Previously published skymaps, i.e. bayestar.multiorder.fits,0 and bayestar.multiorder.fits,1, are both affected and should be disregarded.
Parameter estimation has been performed using Bilby [1] and a new sky map (using only LIGO Livingston and Virgo data), Bilby.offline0.multiorder.fits,0, distributed via GCN Notice, is available for retrieval from the GraceDB event page:
https://gracedb.ligo.org/superevents/S240925n
Assuming the candidate 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 for maximum neutron star mass. The probability that either of the binary components lies between 3 and 5 solar masses (HasMassGap) is 7%.
For the Bilby.offline0.multiorder.fits,0 sky map, the 90% credible region is 1748 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 323 +/- 70 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. PRD 108, 123040 (2023) doi:10.1103/PhysRevD.108.123040
[2] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe
GCN Circular 37609
Subject
LIGO/Virgo/KAGRA S240925n: NED Galaxies in the Localization Volume
Date
2024-09-25T15:52:55Z (8 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 S240925n-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 42329 galaxies within the 90% containment volume, and we list here the top 20 galaxies sorted by the joint probability of the 3D localization and the WISE W1 luminosity (an observable proxy for stellar mass). For the full or top 20 list of galaxies in the 90% volume go either to the NED Gravitational Wave Followup service at https://ned.ipac.caltech.edu/uri/NED::GWF/ or click on the following links:
Full List Download: https://ned.ipac.caltech.edu/uri/NED::GWFglist/fits/S240925n/4
Top 20 List Download: https://ned.ipac.caltech.edu/uri/NED::GWFglist/fits/S240925n/4/20
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 follow-up 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|
|-------------------------|--------------|--------------|-------|-----------|-----------|-------|---------|------------|------------|------------|------------|--------|----------|
|WISEA J062805.37-433822.4| 97.02237| -43.63942| G| 353.30| null| null| null| 13.407| 0.166| 10.531| 0.006|8.65e-07| 1.65e-10|
|WISEA J082912.08+093324.3| 127.30033| 9.55669| G| 300.62| 0.10| null| null| 13.544| 0.318| 9.710| 0.006|3.75e-07| 1.11e-10|
|WISEA J071238.60-372350.1| 108.16138| -37.39731| G| 390.44| null| null| null| 13.392| 0.189| 9.730| 0.006|2.07e-07| 1.08e-10|
|WISEA J070803.77-354236.4| 107.01575| -35.71003| G| 328.72| null| null| null| 12.425| 0.144| 10.393| 0.006|5.43e-07| 1.07e-10|
|WISEA J061819.45-434436.6| 94.58121| -43.74347| G| 370.50| 0.65| 20.752| 0.288| 11.534| 0.065| 11.355| 0.008|1.07e-06| 1.04e-10|
| LCSB S1127P| 124.68167| -5.27042| G| 288.80| 0.79| 19.041| 0.091| 12.474| 0.142| 9.606| 0.006|3.23e-07| 9.65e-11|
|WISEA J081327.05-104947.3| 123.36275| -10.82981| G| 334.80| null| 21.777| 0.343| 12.588| 0.130| 9.678| 0.006|2.52e-07| 9.54e-11|
|WISEA J073059.04-315148.7| 112.74613| -31.86356| G| 346.09| null| null| null| 13.600| 0.199| 10.124| 0.006|3.04e-07| 8.52e-11|
|WISEA J070820.06-363048.2| 107.08383| -36.51381| G| 379.19| null| null| null| 13.096| 0.187| 11.119| 0.006|6.00e-07| 8.29e-11|
|WISEA J061611.50-442317.6| 94.04800| -44.38825| G| 294.82| 0.65| null| null| 12.556| 0.098| 10.622| 0.006|6.79e-07| 8.28e-11|
|WISEA J060209.36-452357.6| 90.53908| -45.39936| G| 384.51| null| 19.583| 0.110| 13.598| 0.217| 11.579| 0.007|8.76e-07| 7.51e-11|
|WISEA J061409.91-454035.8| 93.54125| -45.67661| G| 402.08| null| null| null| 13.766| 0.117| 10.605| 0.006|3.24e-07| 7.45e-11|
|WISEA J051216.45-480857.2| 78.06850| -48.14919| G| 337.91| 0.65| null| null| 12.125| 0.095| 10.653| 0.006|4.79e-07| 7.40e-11|
|WISEA J075243.04-243418.1| 118.17925| -24.57167| G| 429.53| null| null| null| 13.189| 0.220| 9.554| 0.006|9.88e-08| 7.27e-11|
|WISEA J063117.86-431255.9| 97.82442| -43.21550| G| 300.09| 0.65| null| null| 12.542| 0.092| 10.771| 0.006|6.19e-07| 6.84e-11|
|WISEA J055703.16-455202.4| 89.26317| -45.86731| G| 370.68| null| null| null| 13.004| 0.146| 11.788| 0.007|9.80e-07| 6.44e-11|
|WISEA J080912.41-155827.8| 122.30163| -15.97442| G| 363.85| null| null| null| 13.237| 0.167| 9.611| 0.006|1.36e-07| 6.43e-11|
|WISEA J061604.66-444741.9| 94.01942| -44.79497| G| 363.27| 0.65| null| null| 12.326| 0.099| 11.531| 0.006|8.01e-07| 6.41e-11|
|WISEA J072410.09-335347.5| 111.04196| -33.89656| G| 367.11| null| null| null| 12.437| 0.112| 10.727| 0.007|3.60e-07| 6.35e-11|
|WISEA J082326.29-051125.1| 125.85971| -5.19033| G| 265.27| null| 19.749| 0.112| 13.018| 0.169| 9.675| 0.006|2.64e-07| 6.23e-11|
Table 1: Top 20 galaxies in NED-LVS that fall in the 90% probability volume for S240925n 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).
GCN Circular 37687
Subject
LIGO/Virgo/KAGRA S240925n: Updated Sky localization
Date
2024-10-03T03:33:37Z (8 months ago)
From
Sylvia Biscoveanu at Northwestern CIERA <sylvia.biscoveanu@ligo.org>
Via
Web form
The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report:
We have resolved the problem with the calibration of the LIGO Hanford instrument around the time of the compact binary merger (CBC) candidate S240925n (GCN Circulars 37604 and 37607). We have conducted further analysis of the LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) data around the time of this candidate. Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.offline1.multiorder.fits,0, distributed via GCN Notice, is available for retrieval from the GraceDB event page:
https://gracedb.ligo.org/superevents/S240925n
For the Bilby.offline1.multiorder.fits,0 sky map, the 90% credible region is well fit by an ellipse with an area of 17 deg2 described by the following DS9 region (right ascension, declination, semi-major axis, semi-minor axis, position angle of the semi-minor axis):
icrs; ellipse(19h26m, +06d35m, 5.61d, 0.99d, 124.67d)
Marginalized over the whole sky, the a posteriori luminosity distance estimate is 331 +/- 70 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. PRD 108, 123040 (2023) doi:10.1103/PhysRevD.108.123040
GCN Circular 37699
Subject
LIGO/Virgo/KAGRA S240925n: NED Galaxies in the Localization Volume
Date
2024-10-03T17:12:14Z (8 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 S240925n-5-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 3 galaxies within the 90% containment volume, and we list them sorted by the joint probability of the 3D localization and the WISE W1 luminosity (an observable proxy for stellar mass). For the full or top 20 list of galaxies in the 90% volume go either to the NED Gravitational Wave Followup service at https://ned.ipac.caltech.edu/uri/NED::GWF/ or click on the following links:
Full List Download: https://ned.ipac.caltech.edu/uri/NED::GWFglist/fits/S240925n/5
Top 20 List Download: https://ned.ipac.caltech.edu/uri/NED::GWFglist/fits/S240925n/5/20
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 follow-up 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|
|-------------------------|--------------|--------------|-------|-----------|-----------|-------|---------|------------|------------|------------|------------|--------|----------|
|WISEA J195757.14+153451.3| 299.48779| 15.58119| G| 169.59| null| null| null| 11.812| 0.092| 10.338| 0.007|1.66e-06| 7.56e-07|
|WISEA J194523.44+130923.6| 296.34767| 13.15689| G| 255.59| null| null| null| 13.434| 0.232| 11.427| 0.028|1.47e-06| 5.65e-07|
|WISEA J194439.07+121322.1| 296.16292| 12.22275| G| 180.32| null| null| null| 12.310| 0.114| 11.702| 0.015|2.17e-06| 3.29e-07|
Table 1: Top 20 galaxies in NED-LVS that fall in the 90% probability volume for S240925n 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).