Is Planet Nine almost certain, probable, possible or unlikely?

[CJSF]

Twitter thread from Dr. Brown on test data and keeping the hunt for P9 honest:

https://threadreaderapp.com/thread/1...227483136.html

CJSF

[Roger E. Moore]

New study says there's not enough evidence yet to find Planet Nine.

https://arxiv.org/abs/2005.05326
Orbital precession in the distant solar system; further constraining the Planet Nine hypothesis with numerical simulations
Matthew S. Clement, Nathan A. Kaib
[Submitted on 11 May 2020]
The longitudes of perihelia and orbital poles of the solar system's dozen or so most remote detected objects are clustered in a manner inconsistent with that of a random sample of uniformly distributed orbits. While small number statistics and observational biases may explain these features, the statistical significance of the clustering has led to the recent development of the "Planet Nine hypothesis." In the proposed scenario, orbits in the distant solar system are shepherded via secular perturbations from an undetected massive planet on an eccentric orbit. However, the precession of perihelia and nodes in the outer Kuiper Belt and inner Oort Cloud are also affected by the the giant planets, passing stars, and the galactic tide. We perform a large suite of numerical simulations designed to study the orbital alignment of Extreme Trans-Neptunian Objects (ETNOs) and Inner Oort Cloud Objects (IOCOs). In our various integrations that include Planet Nine, we consistently find that >60% of ETNOs and IOCOs that are detectable after 4 Gyr are also anti-aligned in perihelia with the distant massive perturber. However, when we randomly select 17 objects from this sample of remaining orbits, there is significant scatter in the degree of longitude of perihelion and orbital pole clustering that might be observed. Furthermore, we argue that, in the absence of Planet Nine, 17 randomly drawn orbits should still exhibit some clustering even if the underlying distribution is uniform. Thus, we find that still more ETNO and IOCO detections are required to confidently infer the presence of Planet Nine.

[Roger E. Moore]

Doubts persist over whether Planet Nine is a planet or even whether it exists at all. Excellent article.

https://www.popsci.com/story/space/p...even-a-planet/

[borman]

Black Hole or a clump of Dark Matter? Can micro-lensing sort out between the two?
When Adler wrote his three flyby anomaly papers proposing a two fluid dark matter hypothesis. he noted the heat anomaly expressed in Watts/square meter of excess heat beyond what the sun gives for all planets except one, Uranus. Uranus is suspected of having a severe collision that tipped it on its side. It is not known if its present orbit is a result of the collision. Since Dark Matter has less friction than baryons (Bullet Cluster is a possible example), then most Dark Matter trapped by a planet's gravitational well, that might possibly account for a planet's heat excess, would have thrown clear of Uranus to continue on the pre-collision orbit. Discovery of this clump minus baryons so nearby would be a big feather in the hat for the current LCDM hypothesis.

[Roger E. Moore]

Three recent interrelated articles, two from yesterday, about sending lightsail craft to Pluto/black hole/etc.

https://arxiv.org/abs/2005.12280
Searching for Black Holes in the Outer Solar System with LSST
Amir Siraj, Abraham Loeb
[Submitted on 25 May 2020]
Planet Nine has been proposed to potentially be a black hole in the outer solar system. We investigate the accretion flares that would result from impacts of small Oort cloud objects, and find that the upcoming LSST observing program will be able to either rule out or confirm Planet Nine as a black hole within a year. We also find that LSST could rule out or confirm the existence of trapped planet-mass black holes out to the edge of the Oort cloud, indirectly probing the dark matter fraction in primordial black holes and potentially improving upon current limits by orders of magnitude.

https://arxiv.org/abs/2005.12336
Exploration of the outer solar system with fast and small sailcraft
Slava G. Turyshev, Peter Klupar, Abraham Loeb, Zachary Manchester, Kevin Parkin, Edward Witten, S. Pete Worden
[Submitted on 25 May 2020]
Two new interplanetary technologies have advanced in the past decade to the point where they may enable exciting, affordable missions that reach further and faster deep into the outer regions of our solar system: (i) small and capable interplanetary spacecraft and (ii) light-driven sails. Combination of these two technologies could drastically reduce travel times within the solar system. We discuss a new paradigm that involves small and fast moving sailcraft that could enable exploration of distant regions of the solar system much sooner and faster than previously considered. We present some of the exciting science objectives for these miniaturized intelligent space systems that could lead to transformational advancements in the space sciences.

One-atom-thick lightsails from carbon, produced by the ESA.
https://scitechdaily.com/one-atom-th...-star-systems/

[borman]

An accretion flare would sort out between a planetary BH and an equally massive clump of Dark Matter where lensing might not distinguish them.

[bknight]

There was an interesting post by Fraser https://forum.cosmoquest.org/showthr...xist-After-All
in which Samantha Lawler, ***’t. Professor of Astronomy, University of Regina indicated that probably Planet Nine is not a planet when KBO orbits are reviewed recently.

[borman]

The debate will likely continue if more anomalies are detected in the ETNO population. The closest are beyond Neptune whether it migrated or not.

https://www.universetoday.com/136450...e-planet-nine/

[CJSF]

There was an interesting post by Fraser https://forum.cosmoquest.org/showthr...xist-After-All
in which Samantha Lawler, ***’t. Professor of Astronomy, University of Regina indicated that probably Planet Nine is not a planet when KBO orbits are reviewed recently.

I'm curious why the board censored that word after "Lawler". I assume the word is "doesn't" or "isn't"? What did it think you were typing?

In any case, Dr. Lawler talks about observational bias, which is something Dr. Brown and his colleagues have addressed and checked multiple times over the last few years. I'm curious what he might say to this research and conclusion but I don't think he has the time to respond to what must be quite a few rebuttals to Planet 9 coming.

CJSF

[schlaugh]

Abbreviation for “assistant” or “associate.” Just a guess.

[Roger E. Moore]

If Planet Nine is a black hole, would it not emit Hawking radiation?

https://arxiv.org/abs/2006.02944
Detecting Planet 9 via Hawking radiation
Alexandre Arbey, Jérémy Auffinger
[Submitted on 4 Jun 2020]
Concordant evidence points towards the existence of a ninth planet in the Solar System at more than 400 AU from the Sun. In particular, trans-Neptunian object orbits are perturbed by the presence of a putative gravitational source. Since this planet has not yet been observationally found with conventional telescope research, it has been argued that it could be a dark compact object, namely a black hole of probably primordial origin. Within this assumption, we discuss the possibility of detecting Planet 9 via a sub-relativistic spacecraft fly-by and the measure of its Hawking radiation in the radio band. We also present some perspectives related to the study of such a Hawking radiation laboratory in the Solar System.

[Roger E. Moore]

Three recent interrelated articles, two from yesterday, about sending lightsail craft to Pluto/black hole/etc.

https://arxiv.org/abs/2005.12280
Searching for Black Holes in the Outer Solar System with LSST
Amir Siraj, Abraham Loeb
[Submitted on 25 May 2020]
Planet Nine has been proposed to potentially be a black hole in the outer solar system. We investigate the accretion flares that would result from impacts of small Oort cloud objects, and find that the upcoming LSST observing program will be able to either rule out or confirm Planet Nine as a black hole within a year. We also find that LSST could rule out or confirm the existence of trapped planet-mass black holes out to the edge of the Oort cloud, indirectly probing the dark matter fraction in primordial black holes and potentially improving upon current limits by orders of magnitude.

More from the authors on this paper.

https://www.forbes.com/sites/jamieca...y-to-find-out/

[selvaarchi]

The Guardian has put together all we know about the possibility of having another planet way beyond Neptune. There is also the possibility it might be a black hole.

https://www.theguardian.com/science/...w-ninth-planet

You’d think that if you found the first evidence that a planet larger than the Earth was lurking unseen in the furthest reaches of our solar system, it would be a big moment. It would make you one of only a small handful of people in all of history to have discovered such a thing.

But for astronomer Scott Sheppard of the Carnegie Institution for Science in Washington DC, it was a much quieter affair. “It wasn’t like there was a eureka moment,” he says. “The evidence just built up slowly.”

He’s a master of understatement. Ever since he and his collaborator Chad Trujillo of Northern Arizona University, first published their suspicions about the unseen planet in 2014, the evidence has only continued to grow. Yet when asked how convinced he is that the new world, which he calls Planet X (though many other astronomers call it Planet 9), is really out there, Sheppard will only say: “I think it’s more likely than unlikely to exist.”

[selvaarchi]

"Planet Nine and the search for primordial black holes orbiting solar system"

https://www.spacedaily.com/reports/P...ystem_999.html

Scientists at Harvard University and the Black Hole Initiative (BHI) have developed a new method to find black holes in the outer solar system, and along with it, determine once-and-for-all the true nature of the hypothesized Planet Nine. The paper, accepted to The Astrophysical Journal Letters, highlights the ability of the future Legacy Survey of Space and Time (LSST) mission to observe accretion flares, the presence of which could prove or rule out Planet Nine as a black hole.

Dr. Avi Loeb, Frank B. Baird Jr. Professor of Science at Harvard, and Amir Siraj, a Harvard undergraduate student, have developed the new method to search for black holes in the outer solar system, based on flares that result from the disruption of intercepted comets. The study suggests that the LSST has the capability to find black holes by observing for accretion flares resulting from the impact of small Oort cloud objects.

[bknight]

Will we be speaking o planet 9 a decade from now?

[selvaarchi]

"Lighting a Path to Find Planet Nine"

https://www.spacedaily.com/reports/L..._Nine_999.html

The search for Planet Nine - a hypothesized ninth planet in our solar system - may come down to pinpointing the faintest orbital trails in an incredibly dark corner of space.

That's exactly what Yale astronomers Malena Rice and Gregory Laughlin are attempting with a technique that scoops up scattered light from thousands of space telescope images and identifies orbital pathways for previously undetected objects.

"You really can't see them without using this kind of method. If Planet Nine is out there, it's going to be incredibly dim," said Rice, lead author of a new study that has been accepted by The Planetary Science Journal [https://psj.aas.org].

Rice, a Ph.D. student in astronomy and National Science Foundation Graduate Research Fellow, presented the findings Oct. 27 at the annual meeting of the American Astronomical Society's Division for Planetary Sciences.

[Roger E. Moore]

Hunting for Planet 9 using the TESS spacecraft. More on the Rice-Laughlin project.


https://arxiv.org/abs/2010.13791

Exploring Trans-Neptunian Space with TESS: A Targeted Shift-Stacking Search for Planet Nine and Distant TNOs in the Galactic Plane

Malena Rice, Greg Laughlin

We present results from a new pipeline custom-designed to search for faint, undiscovered solar system bodies using full-frame image data from the NASA Transiting Exoplanet Survey Satellite (TESS) mission. This pipeline removes the baseline flux of each pixel before aligning and co-adding frames along plausible orbital paths of interest. We first demonstrate the performance of the pipeline by recovering the signals of three trans-Neptunian objects -- 90377 Sedna (V=20.64), 2015 BP519 (V=21.81), and 2007 TG422 (V=22.32) -- both through shift-stacking along their known sky-projected paths and through a blind recovery. We then apply this blind search procedure in a proof-of-concept survey of TESS Sectors 18 and 19, which extend through a portion of the galactic plane in the Northern Hemisphere. We search for dim objects at geocentric distances d=70−800 au in a targeted search for Planet Nine and any previously unknown detached Kuiper belt objects that may shed light on the Planet Nine hypothesis. With no input orbital information, our present pipeline can reliably recover the signals of distant solar system bodies in the galactic plane with V<21 and current distances d≲150 au, and we elaborate on paths forward to push these limits in future optimizations. The methods described in this paper will serve as a foundation for an all-sky shift-stacking survey of the distant solar system with TESS.

[Roger E. Moore]

Planet 9's effects on the orbits of trans-Neptunian objects, in more detail.


https://arxiv.org/abs/2010.02234

The Resonance Hopping Effect in the Neptune-Planet Nine System

Tali Khain, Juliette Becker, Fred C. Adams

The observed physical clustering of the orbits of small bodies in the distant Kuiper Belt (TNOs) has recently prompted the prediction of an additional planet in the outer solar system. Since the initial posing of the hypothesis, the effects of Planet Nine on the dynamics of the main cluster of TNOs - the objects anti-aligned with its orbit - have been well-studied. In particular, numerical simulations have revealed a fascinating phenomenon, referred to as "resonance hopping", in which these objects abruptly transition between different mean-motion commensurabilities with Planet Nine. In this work, we explore this effect in greater detail, with the goal of understanding what mechanism prompts the hopping events to occur. In the process, we elucidate the often underestimated role of Neptune scattering interactions, which leads to diffusion in the semi-major axes of these distant TNOs. In addition, we demonstrate that although some resonant interactions with Planet Nine do occur, the anti-aligned objects are able to survive without the resonances, confirming that the dynamics of the TNOs are predominantly driven by secular, rather than resonant, interactions with Planet Nine.

[Roger E. Moore]

Using data from the Dark Energy Survey to hunt for TNOs... and Planet Nine. Everyone's getting into the search.


https://arxiv.org/abs/2009.12856

Machine Learning for Searching the Dark Energy Survey for Trans-Neptunian Objects

B. Henghes, O. Lahav, D. W. Gerdes, E. Lin, R. Morgan, T. M. C. Abbott, M. Aguena, S. Allam, J. Annis, S. Avila, E. Bertin, D. Brooks, D. L. Burke, A. CarneroRosell, M. CarrascoKind, J. Carretero, C. Conselice, M. Costanzi, L. N. da Costa, J. DeVicente, S. Desai, H. T. Diehl, P. Doel, S. Everett, I. Ferrero, J. Frieman, J. García-Bellido, E. Gaztanaga, D. Gruen, R. A. Gruendl, J. Gschwend, G. Gutierrez, W. G. Hartley, S. R. Hinton, K. Honscheid, B. Hoyle, D. J. James, K. Kuehn, N. Kuropatkin, J. L. Marshall, P. Melchior, F. Menanteau, R. Miquel, R. L. C. Ogando, A. Palmese, F. Paz-Chinchón, A. A. Plazas, A. K. Romer, C. Sánchez, E. Sanchez, V. Scarpine, M. Schubnell, S. Serrano, M. Smith, M. Soares-Santos, E. Suchyta, G. Tarle, C. To, R. D. Wilkinson (DES collaboration)

In this paper we investigate how implementing machine learning could improve the efficiency of the search for Trans-Neptunian Objects (TNOs) within Dark Energy Survey (DES) data when used alongside orbit fitting. The discovery of multiple TNOs that appear to show a similarity in their orbital parameters has led to the suggestion that one or more undetected planets, an as yet undiscovered "Planet 9", may be present in the outer Solar System. DES is well placed to detect such a planet and has already been used to discover many other TNOs. Here, we perform tests on eight different supervised machine learning algorithms, using a dataset consisting of simulated TNOs buried within real DES noise data. We found that the best performing classifier was the Random Forest which, when optimised, performed well at detecting the rare objects. We achieve an area under the receiver operating characteristic (ROC) curve, (AUC) = 0.996 ± 0.001. After optimizing the decision threshold of the Random Forest, we achieve a recall of 0.96 while maintaining a precision of 0.80. Finally, by using the optimized classifier to pre-select objects, we are able to run the orbit-fitting stage of our detection pipeline five times faster.