IceCube-250207A

The IceCube Collaboration (http://icecube.wisc.edu/) reports:

On 2025-02-07 at 02:07:55.27 UT IceCube detected a track-like event with a high probability of being of astrophysical origin. The event was selected by the ICECUBE_Astrotrack_BRONZE alert stream. The average astrophysical neutrino purity for bronze alerts is 30%. This alert has an estimated false alarm rate of 1.45 events per year due to atmospheric backgrounds. The IceCube detector was in a normal operating state at the time of detection.

After the initial automated alert (https://gcn.gsfc.nasa.gov/notices_amon_g_b/140472_78196104.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to:

Date: 2025-02-07
Time:   02:07:55.27 UT
RA: 132.93 (+2.05, -1.89 deg 90% PSF containment) J2000
Dec: 20.66 (+1.28, -1.40 deg 90% PSF containment) J2000

Two Fermi 4FGL or 3FHL catalog sources are in the 90% uncertainty region: 4FGL J0854.8+2006 and 4FGL J0856.8+2056, located 0.9 deg and 1.2 deg away from the best-fit position, respectively.
We encourage further follow-up by ground and space-based instruments to help identify a possible astrophysical source for the candidate neutrino.

The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc@icecube.wisc.edu

S. Garrappa (Weizmann Institute of Science),  L. Pfeiffer (Univ. of Wuerzburg), C. Bartolini (INFN Bari), S. Buson (DESY, Univ. of Wuerzburg) and P. M. Veres (Ruhr University Bochum) on behalf of the Fermi-LAT collaboration:

We report an analysis of observations of the vicinity of the high-energy IC250207A neutrino event (GCN 39203
Loading...
 
 ) with all-sky survey data from the Large Area Telescope (LAT), on board the Fermi Gamma-ray Space Telescope. The IceCube event was detected on 2025-02-07 02:07:55.27 UTC (T0) with J2000 position RA = 132.93 (+2.05, -1.89) deg, Decl. = 20.66 (+1.28, -1.40) deg 90% PSF containment. Two cataloged gamma-ray sources are found within the 90% IC250207A localization error (The Fourth Fermi-LAT catalog, 4FGL-DR4, The Fermi-LAT collaboration 2023, arXiv:2307.12546
Loading...
 
 ). These are 4FGL J0854.8+2006 (associated with the FSRQ OJ 287) and 4FGL J0856.8+2056 (associated with the FSRQ TXS 0853+211) at 0.9 deg and 1.2 deg from the best-fit neutrino position, respectively. Based on a preliminary analysis of the LAT data over the timescales of 1-day and 1-month before T0, these objects are not significantly detected at gamma-rays.

We searched for the existence of intermediate (days to years) timescale emission from a new gamma-ray transient source. Preliminary analysis indicates no significant (>5sigma) new excess emission (> 100 MeV) within the IC250207A 90% confidence localization. Assuming a power-law spectrum (photon index = 2.0 fixed) for a point source at the IceCube best-fit position, the >100 MeV flux upper limit (95% confidence) is <2.4e-10 ph cm^-2 s^-1 for ~16-years (2008-08-04 / T0), <6.9e-09(<5.6e-8) ph cm^-2 s^-1 for a 1-month (1-day) integration time before T0.

Since Fermi normally operates in an all-sky scanning mode, regular monitoring of this source will continue. For this source, the Fermi-LAT contact person is S. Garrappa (simone.garrappa at weizmann.ac.il). 

The Fermi LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.

The IceCube Collaboration (http://icecube.wisc.edu/) reports:

IceCube has performed a search [1] for additional track-like muon neutrino events arriving from the direction of IceCube-250207A (https://gcn.nasa.gov/circulars/39203
Loading...
 
 ) in a time range of 1000 seconds centered on the alert event time (2025-02-07 01:59:35.270 UTC to 2025-02-07 02:16:15.270 UTC) during which IceCube was collecting good quality data. Excluding the event  that prompted the alert, zero track-like events are found within the 90% containment region of IceCube-250207A. 

The IceCube sensitivity to neutrino point sources with an E^-2.5 spectrum (E^2 dN/dE at 1 TeV) within the locations spanned by the 90% spatial containment region of IceCube-250207A is 1.4e-01 GeV cm^-2 in a 1000 second time window. 90% of events IceCube would detect from a source at this declination with an E^-2.5 spectrum have energies in the approximate energy range between 2e+02 GeV and 9e+04 GeV. 

A subsequent search was performed including 2 days of data centered on the alert event time (2025-02-06 02:07:55.270 UTC to 2025-02-08 02:07:55.270 UTC). In this case, we report a p-value of 0.20, consistent with no significant excess of track events. The IceCube sensitivity to neutrino point sources with an E^-2.5 spectrum (E^2 dN/dE at 1 TeV) within the locations spanned by the 90% spatial containment region of IceCube-250207A is 1.7e-01 GeV cm^-2 in a 2 day time window. 

The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc@icecube.wisc.edu.

[1] IceCube Collaboration, R. Abbasi  et al., ApJ 910 4 (2021)

Jannis Necker, Akshay Eranhalodi (DESY), Robert Stein (JSI), Sven Weimann (Ruhr University Bochum), and Anna Franckowiak (Ruhr University Bochum) report:

On behalf of the Zwicky Transient Facility (ZTF) and Global Relay of Observatories Watching Transients Happen (GROWTH) collaborations: 

As part of the ZTF neutrino follow up program (Stein et al. 2023), we observed the localization region of the neutrino event IceCube-250207A (Sommani et. al, GCN 39203
Loading...
 
 ) with the Palomar 48-inch telescope, equipped with the 47 square degree ZTF camera (Bellm et al. 2019, Graham et al. 2019). We started observations in the g- and r-band beginning at 2025-02-08 06:52 UTC, approximately 28.7 hours after event time. We covered 98.9% (9.8 sq deg) of the reported localization region. This estimate accounts for chip gaps. Each exposure was 300s with a typical depth of 21.0 mag. 
 
The images were processed in real-time through the ZTF reduction and image subtraction pipelines at IPAC to search for potential counterparts (Masci et al. 2019). AMPEL (Nordin et al. 2019, Stein et al. 2021) was used to search the alerts database for candidates. We reject stellar sources (Tachibana and Miller 2018) and moving objects, and apply machine learning algorithms (Mahabal et al. 2019) . We are left with the following high-significance transient candidate by our pipeline, lying within the 90.0% localization of the skymap.

+--------------------------------------------------------------------------------+
| ZTF Name     | IAU Name  | RA (deg)    | DEC (deg)   | Filter | Mag   | MagErr |
+--------------------------------------------------------------------------------+
| ZTF25aafgnar |  -------  | 131.6422069 | +19.3306551 | r      | 20.68 | 0.16   |
+--------------------------------------------------------------------------------+

ZTF25aafgnar was first detected on 2025-01-19. The source is somewhat red, with a g-r colour of 0.3. Due to the offset of 0.92 arcsec from the nucleus of its host SDSS J084634.07+191950.9, it appears most likely to be a supernova. 

Forced photometry reveals ZTF pre-detections beginning on 2025-01-19, demonstrating that the supernova predates the detection of IC250207A. The source reached a peak magnitude of m=20.2 in g-band on 2025-01-23, and has since faded by 0.5 mag. Photometric redshift estimates for the host galaxy from Legacy Survey suggest a distance of z = 0.26 +/- 0.06, with a 95% lower limit of z>0.165, implying a peak absolute magnitude of at least M<-19.4. 

The colour and implied absolute magnitude are consistent with a supernova origin for this source. 

The timing of the neutrino detection excludes any choked-jet neutrino production models, but CSM-interaction neutrino production models would still be viable.

Spectroscopic observations are planned to determine the nature of this transient. 

ZTF and GROWTH are worldwide collaborations comprising Caltech, USA; IPAC, USA; WIS, Israel; OKC, Sweden; JSI/UMd, USA; DESY, Germany; TANGO, Taiwan; UW Milwaukee, USA; LANL, USA; TCD, Ireland; IN2P3, France.

GROWTH acknowledges generous support of the NSF under PIRE Grant No 1545949.
Alert distribution service provided by DIRAC@UW (Patterson et al. 2019).
Alert database searches are done by AMPEL (Nordin et al. 2019).
Alert filtering is performed with the nuztf (Stein et al. 2021, https://github.com/desy-multimessenger/nuztf ).

K. Labzina,  K.Zhirkov, V.Lipunov, E.Gorbovskoy, G.Antipov, D.Vlasenko,
A.Kuznetsov, N.Tyurina, P.Balanutsa, A.Chasovnikov, D.Kuvshinov,
V.Topolev,Ya.Kechin,Yu.Tselik, K.Minkina
(Lomonosov Moscow State University, SAI, Physics Department),
O.Gress, N.Budnev, O.Ershova (ISU),
C.Francile,  F. Podesta, R.Podesta, E. Gonzalez  (Observatorio Astronomico Felix Aguilar (OAFA),
D.Buckley (SAAO), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity),
R.Rebolo (The Instituto de Astrofisica de Canarias),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,
A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory)



MASTER600-Tunka robotic telescope  located in Russia (Applied Physics Institute,  Irkutsk State University;  Lipunov, Kornilov, Gorbovskoy, Tiurina & Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591,
pp.http://www.pereplet.ru/lipunov/625.html#625)
 started IceCube-250207A (IceCube  GCN#39203
Loading...
 
 )of the Ice Cube Alert 250207.09 error box  ~11h   after trigger time at 2025-02-07  13:53:05 UT,  with upper limit up to  19.2 mag.
 (see cover map:
https://master.sai.msu.ru/site/master2/observ.php?id=2770114)

We analyzed MASTER archive images since 2010 of the source, that can be related with this event.
Global MASTER Net detected QSOJ0854+2006 inside 1 sigma. QSOJ0854+2006 (https://simbad.u-strasbg.fr/simbad/sim-coo) fading to 16.6m
during last nights observations.


Fortunately, data from the ATLAS network (Tonry et al., 2018, PASP, 13, 164505) are available, which show that ~24 hours before the neutrino alert (05.13 feb 2025.) the blazar QSOJ0854+2006 was at its local standard brightness, it was 1 magnitude brighter: 15.1 . After a few days, the blazar returned to its original bright state.
Thus, we report the observation of an Zhirkov effect discovered earlier (The Astrophysical Journal Letters, 896, L19, 2020) .



The MASTER archive light curve from 2010 year is available at
http://www.pereplet.ru/lipunov/images/ATbbo_galaxy_arhive_midi.jpg