Tue, 02/08/2022 - 23:01
An interesting paper on a potential binary SMBH imminent collision was published at: https://arxiv.org/pdf/2201.11633.pdf recently.
Researcher Dr. Ning Jiang has requested observations in B and V of NSV 6690, the optical AGN of SDSSJ1430+2303.
AAVSO Sequence Team member Chuck Cynamon has updated the sequence and chart for NSV 6690.
Several observers are already contributing data to the database on this object.
Dr. Jiang is especially asking for data from systems with 1 arcsec pixel size or less, but all data is welcome.
Spectra are appreciated.
This looks interesting, thanks for posting it here.
It is a shame that the proposed merger will appear before the LISA gravitational wave space mission will be up.
I assume that the PI has already requested an AAVSO campaign for this?
He has not formally asked.
Both Arne Henden and I have been in contact with him. He had no knowledge of AAVSO and didn't seem to understand the idea of requesting a campaign. But he DID tell us what bands he'd like data in and that he'd welcome further data. Their only data to date is from ZTF.
BTW: who does one officially request a campaign from?? Is there a form? Just an email?? What's the process?
The information for campaigns can be found by going to the "Tools and Observer Resources" link on the main page. Click on the "AAVSO Alerts and Observing Campaigns" link. This will give you all the information you need.
Specifically, you can refer the researcher(s) to this page :
which includes a link to this informal "form" to request a campaign:
As you can see, requesting a campaign is no big effort but has many benefits:
So I highly recommend to take this extra step. Of course we are here to help with any questions surrounding starting a campaign.
I want to caution folks not to get too excited about this object just yet. I think it's worth observing, but just from the existing optical photometry, it doesn't look out of the ordinary relative to other variability from accreting supermassive black holes. Lots of them show apparent periodicities over short amounts of time due to a process called red noise. If you grab the plots from stock prices versus time for a every company, and then just look at short segments, you'll see some cases where the price appears to be periodic, or to "chirp" for short amounts of time, but then, when you zoom out and look at longer segments, there won't be any periodicities. AGN variability has a lot of the same mathematical characteristics as stock prices. In the past 10 years or so, with the huge all-sky variability surveys, there have been a lot of claims of periodicities in AGN light curves, but pretty much all of them have fewer than 10 cycles, and they have generally not held up as longer data sets were obtained. I wouldn't classify this light curve as being any more convincing of a binary black hole close to merging than the others. This particular object has some peculiarities with the emission lines in the spectra as well. I don't know what to make of that, but I don't think it's particularly clear evidence that a merger is about to take place.
My personal view is to be very skeptical of this, but I also think that even though the chance of this being a merger is small, the rewards if it does turn out to be one are potentially enormous, so it may still be worth observing. I just thought it important to make sure people understand going in that the claims in the paper (which is submitted, but not published nor event accepted for publication) are not particularly convincing, so that people don't invest a lot of effort and then end up disappointed.
All very true, thanks for putting this all into perspective.
I guess we as amateurs should probably not care too much about what this really is tho :-) : by putting the paper on arxiv the authors made an admittedly steep claim, but if we can help to confirm or falsify this prediction, it will be very useful in both cases.
I really think there will be much to learn, one day, by testing different ideas about what actually causes AGN variability against historic light curves, and I guess we amateurs can provide very high quality and high cadence light curves, e.g. see what has been achieved with S5 1803+78. So I'm confident this should be useful in the end, one way or another.
Yes, I agree that it will be useful in the end, and just wanted people to understand that:
(1) professionally driven time domain surveys are going to start generating large numbers of AGN with apparently unusual light curves, but just because the number of objects sampled is so large
(2) lots of professional astronomers have a poor understanding of how common it is for red noise to produce spurious periods so there will be lots of people claiming periodicities that aren't real.
Also there's another point, which is that there are lots of phenomena that can make a periodicity besides orbits, so even with real periodicities, it won't immediately mean a black hole merger.
And since this object does have something unusual going on with the emission lines, I think studying the variability of it is interesting. Also, if this object gets more AAVSO observers looking at AGN, that would also be a great result.
Some coverage of this subject, including discussion by scientists not on the author list of the paperin question : https://www.science.org/content/article/crash-titans-imminent-merger-giant-black-holes-predicted
I think that article is really well done, in terms of indicating why this is likely to be something other than a black hole merger, but also worth observing on the off chance that it is one.
My images of NSV 6690 from 04/03/2022 show a blue companion at mag 18.5 immediately west of NSV 6690. Earlier images did not show this. It is not visible in V or I images.
Interesting. can you give coordinates or a separation in arcsec? How close is it?
You might want to crossmatch that extra source with a somewhat deep finder chart generated with SDSS images. This is deep enough to give you an idea about the extend of the host galaxy and some faint known objects in the vicinity.
I hd not seen that site! Thank you.
Further analysis seems to indicate it is a ghost from previous image.
Sorry about that!
No worries! Always good to investigate unusual stuff.
Low resolution spectroscopy of NSV6690 is tough but possible. Here is my first attempt
(3 hours exposure at R~130 using a modified ALPY200 and 280mm aperture)
fits files in the BAA spectroscopy database
A further attempt by me and one at higher resolution (R~500) by Simon de Visscher using an ALPY600 and 400mm aperture
The authors were appreciative of the results which may show changes on the blue flank of the H alpha emission which they planned to follow up, though I have not had any further feedback
Do you plan to repeat this over the comming months to test the claim of the "Tick-Tock" paper that there is something evolving in this AGN over relatively short timescales?
If people are wondering whether it's still worthwhile to observe this target, there is a new (pre-print) paper out that seems to indicate this is indeed still an interesting target:
This paper uses X ray observations and claims high variability.
So I guess we should continue to have an "eye" on this one.