Terrestrial and Martian Heat Flow Limits on Dark Matter

https://arxiv.org/pdf/1909.11683

September 27, 2019

Abstract
If dark matter is efficiently captured by a planet, energy released in its annihilation can exceed
that planet’s total heat output. Building on prior work, we treat Earth’s composition and dark
matter capture in detail and present improved limits on dark matter-nucleon scattering cross
sections for dark matter masses ranging from 0.1 to 10^10 GeV. We also extend Earth limits by
applying the same treatment to Mars. We find that Earth and Mars heating bounds are alleviated for dark matter s-wave self-annihilation cross sections . 10−37 cm2

Strongly-interacting DM can appreciably raise the temperature of the Earth and Mars through
capture and subsequent annihilation.

DM is a light particle (in this case lighter than a small asteroid).

The most stringent limit on DM’s nucleon interactions is obtained from planetary heating when
the DM annihilation rate equals the DM capture rate. This occurs for DM with a sufficiently large self-annihilation cross section.

We assume Mars’ crust to have a thickness of 50 km.

Many geological studies and models have been performed that estimate the total heat flux from within the Earth, all of which find the total heat flux to be around 44 TW. Some of this flux has been attributed to known processes, such as emission from radiogenic sources like uranium and thorium present in the Earth. However, to be conservative we will attribute all of the observed 44 TW to DM annihilation, when setting bounds on DM parameters. We similarly take a total heat flux of 3.5 TW for Mars, which is the maximum value.

Is there any observational evidence for the hypothesised dark matter annihilation?

p.s. It seems I didn’t know how to spell annihilation. How come it has two ns?

The Rev Dodgson said:

Is there any observational evidence for the hypothesised dark matter annihilation?

p.s. It seems I didn’t know how to spell annihilation. How come it has two ns?

same root as nihilism stick an an on the front of it.

to nothing

(i just made all that up but it seems reasonable to me)

Dropbear said:

The Rev Dodgson said:

Is there any observational evidence for the hypothesised dark matter annihilation?

p.s. It seems I didn’t know how to spell annihilation. How come it has two ns?

same root as nihilism stick an an on the front of it.

to nothing

(i just made all that up but it seems reasonable to me)

I’d go as far as saying bleeding obvious, now you point it out :)

The Rev Dodgson said:

Is there any observational evidence for the hypothesised dark matter annihilation?

Yes. Galaxy rotation curves.

From the very earliest days of discovering the gravitational influence of dark matter, it was known that dark matter has to have a flat density profile throughout each galaxy.

But numerical simulation of dark matter distributions resuoted in a density spike in the middle of each galaxy. The simplest way to reconcile the contradiction was to use annihilation of dark matter in regions of high dark matter density to remove the density spike and give a flat density profile as observed.

This isn’t so ridiculous because a lot of subatomic particles are their own antiparticle. These include the photon and some mesons such as the uncharged pion.

So astronomers went looking for photons generated by dark matter annihilation in the centre of the Milky Way. And didn’t find it. Or rather, almost didn’t find it. There is a peculiar narrowband gamma ray signiature from the galaxy core that nobody can explain. It could be the signal of dark matter annihilation, but if so then it’s much weaker than expected.

So the possibility of dark matter annihilation remains unresolved, and the lack of a dark matter density cusp in the centre of galaxies remains unexplained.

So far as I know.

The Rev Dodgson said:

Is there any observational evidence for the hypothesised dark matter annihilation?

p.s. It seems I didn’t know how to spell annihilation. How come it has two ns?

probably because it’s said an nih…, sorta

mollwollfumble said:

The Rev Dodgson said:

Is there any observational evidence for the hypothesised dark matter annihilation?

Yes. Galaxy rotation curves.

From the very earliest days of discovering the gravitational influence of dark matter, it was known that dark matter has to have a flat density profile throughout each galaxy.

But numerical simulation of dark matter distributions resuoted in a density spike in the middle of each galaxy. The simplest way to reconcile the contradiction was to use annihilation of dark matter in regions of high dark matter density to remove the density spike and give a flat density profile as observed.

This isn’t so ridiculous because a lot of subatomic particles are their own antiparticle. These include the photon and some mesons such as the uncharged pion.

So astronomers went looking for photons generated by dark matter annihilation in the centre of the Milky Way. And didn’t find it. Or rather, almost didn’t find it. There is a peculiar narrowband gamma ray signiature from the galaxy core that nobody can explain. It could be the signal of dark matter annihilation, but if so then it’s much weaker than expected.

So the possibility of dark matter annihilation remains unresolved, and the lack of a dark matter density cusp in the centre of galaxies remains unexplained.

So far as I know.

OK sound reasonable.

It seems to me that the most likely reason for the lack of the cusp is that dark matter is completely different to what it is hypothesised to be, so the modelling is completely wrong.

But what would I know?

The Rev Dodgson said:

mollwollfumble said:

The Rev Dodgson said:

Is there any observational evidence for the hypothesised dark matter annihilation?

Yes. Galaxy rotation curves.

From the very earliest days of discovering the gravitational influence of dark matter, it was known that dark matter has to have a flat density profile throughout each galaxy.

But numerical simulation of dark matter distributions resuoted in a density spike in the middle of each galaxy. The simplest way to reconcile the contradiction was to use annihilation of dark matter in regions of high dark matter density to remove the density spike and give a flat density profile as observed.

This isn’t so ridiculous because a lot of subatomic particles are their own antiparticle. These include the photon and some mesons such as the uncharged pion.

So astronomers went looking for photons generated by dark matter annihilation in the centre of the Milky Way. And didn’t find it. Or rather, almost didn’t find it. There is a peculiar narrowband gamma ray signiature from the galaxy core that nobody can explain. It could be the signal of dark matter annihilation, but if so then it’s much weaker than expected.

So the possibility of dark matter annihilation remains unresolved, and the lack of a dark matter density cusp in the centre of galaxies remains unexplained.

So far as I know.

OK sound reasonable.

It seems to me that the most likely reason for the lack of the cusp is that dark matter is completely different to what it is hypothesised to be, so the modelling is completely wrong.

But what would I know?

what is dark matter hypothesized to be?

JudgeMental said:

what is dark matter hypothesized to be?

dark and mattery

JudgeMental said:

The Rev Dodgson said:

mollwollfumble said:

Yes. Galaxy rotation curves.

From the very earliest days of discovering the gravitational influence of dark matter, it was known that dark matter has to have a flat density profile throughout each galaxy.

But numerical simulation of dark matter distributions resuoted in a density spike in the middle of each galaxy. The simplest way to reconcile the contradiction was to use annihilation of dark matter in regions of high dark matter density to remove the density spike and give a flat density profile as observed.

This isn’t so ridiculous because a lot of subatomic particles are their own antiparticle. These include the photon and some mesons such as the uncharged pion.

So astronomers went looking for photons generated by dark matter annihilation in the centre of the Milky Way. And didn’t find it. Or rather, almost didn’t find it. There is a peculiar narrowband gamma ray signiature from the galaxy core that nobody can explain. It could be the signal of dark matter annihilation, but if so then it’s much weaker than expected.

So the possibility of dark matter annihilation remains unresolved, and the lack of a dark matter density cusp in the centre of galaxies remains unexplained.

So far as I know.

OK sound reasonable.

It seems to me that the most likely reason for the lack of the cusp is that dark matter is completely different to what it is hypothesised to be, so the modelling is completely wrong.

But what would I know?

what is dark matter hypothesized to be?

I have no idea, but presumably the people who model it do have.

The Rev Dodgson said:

mollwollfumble said:

The Rev Dodgson said:

Is there any observational evidence for the hypothesised dark matter annihilation?

Yes. Galaxy rotation curves.

From the very earliest days of discovering the gravitational influence of dark matter, it was known that dark matter has to have a flat density profile throughout each galaxy.

But numerical simulation of dark matter distributions resuoted in a density spike in the middle of each galaxy. The simplest way to reconcile the contradiction was to use annihilation of dark matter in regions of high dark matter density to remove the density spike and give a flat density profile as observed.

This isn’t so ridiculous because a lot of subatomic particles are their own antiparticle. These include the photon and some mesons such as the uncharged pion.

So astronomers went looking for photons generated by dark matter annihilation in the centre of the Milky Way. And didn’t find it. Or rather, almost didn’t find it. There is a peculiar narrowband gamma ray signiature from the galaxy core that nobody can explain. It could be the signal of dark matter annihilation, but if so then it’s much weaker than expected.

So the possibility of dark matter annihilation remains unresolved, and the lack of a dark matter density cusp in the centre of galaxies remains unexplained.

So far as I know.

OK sound reasonable.

It seems to me that the most likely reason for the lack of the cusp is that dark matter is completely different to what it is hypothesised to be, so the modelling is completely wrong.

But what would I know?

Considering we can’t observe or detect it directly that’s a fair point

Cymek said:

The Rev Dodgson said:

mollwollfumble said:

Yes. Galaxy rotation curves.

From the very earliest days of discovering the gravitational influence of dark matter, it was known that dark matter has to have a flat density profile throughout each galaxy.

But numerical simulation of dark matter distributions resuoted in a density spike in the middle of each galaxy. The simplest way to reconcile the contradiction was to use annihilation of dark matter in regions of high dark matter density to remove the density spike and give a flat density profile as observed.

This isn’t so ridiculous because a lot of subatomic particles are their own antiparticle. These include the photon and some mesons such as the uncharged pion.

So astronomers went looking for photons generated by dark matter annihilation in the centre of the Milky Way. And didn’t find it. Or rather, almost didn’t find it. There is a peculiar narrowband gamma ray signiature from the galaxy core that nobody can explain. It could be the signal of dark matter annihilation, but if so then it’s much weaker than expected.

So the possibility of dark matter annihilation remains unresolved, and the lack of a dark matter density cusp in the centre of galaxies remains unexplained.

So far as I know.

OK sound reasonable.

It seems to me that the most likely reason for the lack of the cusp is that dark matter is completely different to what it is hypothesised to be, so the modelling is completely wrong.

But what would I know?

Considering we can’t observe or detect it directly that’s a fair point

seeing as we only model DM on what we can infer from how it appears to interact with ordinary matter…

https://www.sciencealert.com/planet-9-could-be-an-ancient-black-hole-says-new-study?perpetual=yes&limitstart=1

Cymek said:

The Rev Dodgson said:

mollwollfumble said:

Yes. Galaxy rotation curves.

From the very earliest days of discovering the gravitational influence of dark matter, it was known that dark matter has to have a flat density profile throughout each galaxy.

But numerical simulation of dark matter distributions resuoted in a density spike in the middle of each galaxy. The simplest way to reconcile the contradiction was to use annihilation of dark matter in regions of high dark matter density to remove the density spike and give a flat density profile as observed.

This isn’t so ridiculous because a lot of subatomic particles are their own antiparticle. These include the photon and some mesons such as the uncharged pion.

So astronomers went looking for photons generated by dark matter annihilation in the centre of the Milky Way. And didn’t find it. Or rather, almost didn’t find it. There is a peculiar narrowband gamma ray signiature from the galaxy core that nobody can explain. It could be the signal of dark matter annihilation, but if so then it’s much weaker than expected.

So the possibility of dark matter annihilation remains unresolved, and the lack of a dark matter density cusp in the centre of galaxies remains unexplained.

So far as I know.

OK sound reasonable.

It seems to me that the most likely reason for the lack of the cusp is that dark matter is completely different to what it is hypothesised to be, so the modelling is completely wrong.

But what would I know?

Considering we can’t observe or detect it directly that’s a fair point

A very fair point. Whatever dark matter really is, nobody really has a clue. There is probably a good published explanation out there somewhere, but it’s as likely as not to be in some obscure Lithuanian journal that nobody’s heard of.

Michael V said:

https://www.sciencealert.com/planet-9-could-be-an-ancient-black-hole-says-new-study?perpetual=yes&limitstart=1

I have no intention of reading that.