contamination model

[jpdeleon]

See https://github.com/hpparvi/parviainen_2020_toi_519/tree/main/src

[jpdeleon]

I ran Hannu's transit+contamination modeling he used for TOI 263 and TOI 519 paper, this time using M3 lightcurves.

I used the following priors:

• zero epoch
• period
• transit duration from transit modeling results;

and

• limb darkening
• host Teff based on spectroscopy results

Among them, the spectroscopic priors are most important. Without limb darkening prior, transit fit in g-band is boxy perhaps due to sparse sampling. Without host Teff prior, the posteriors are not well behaved.

This set-up yields a wide/almost bimodal solution on rhostar as shown here.

I checked that this high density solution is comparable to the highest stellar density for M dwarfs (33 g/cc) reported in exofop.

If I impose a narrower prior on rhostar: Uniform(14,22), based on spectroscopy results, then posteriors are towards the edge of the rhostar prior as expected as shown here.

In either case, we can strongly constrain the possibility of a blended source with a Teff very different from that of the host. Also, if you look at the "truths"/blue lines in the corner plots, they are not quite far from the mode in either case. What do you guys think? @john-livingston @Mayuko-Mori I will also ask Hannu for comments.

[john-livingston]

In general, you shouldn't use both duration and rho star priors. Just use P/T0/LD (and host Teff, in this case) priors first, then try it with a Gaussian rho star prior.

What do the "truths"/blue lines in the posterior represent, the MAP solution?

---

From: Jerome de Leon @.> Sent: Monday, February 14, 2022 10:24 AM To: jpdeleon/toi1696 @.> Cc: John Livingston @.>; Mention @.> Subject: Re: [jpdeleon/toi1696] contamination model (Issue #8)

I ran Hannu's transit+contamination modeling he used for TOI 263 and TOI 519 paper, this time using M3 lightcurves.

I used the following priors:

• zero epoch
• period
• transit duration from transit modeling results;

and

• limb darkening
• host effective temperature based on spectroscopy results

Among them, the spectroscopic priors are most important. Without limb darkening prior, transit fit in g-band is boxy perhaps due to sparse sampling. Without host Teff prior, the posteriors are not well behaved.

This set-up yields a bimodal solution on rhostar as shown in herehttps://github.com/jpdeleon/toi1696/blob/main/paper/figures/contaminated_lpf_corner_wide_rhostar_prior.png.

I checked that this high density solution is comparable to the highest stellar density for M dwarfs (33 g/cc) reported in exofop.

If I impose a narrower prior on rhostar: Uniform(14,22), based on spectroscopy results, then posteriors are towards the edge of the rhostar prior as expected as shown herehttps://github.com/jpdeleon/toi1696/blob/main/paper/figures/contaminated_lpf_corner_narrow_rhostar_prior.png.

In either case, we can strongly constrain the possibility of a blended source with a Teff very different from that of the host. Also, if you look at the "truths"/blue lines in the posterior, they are not quite far from the mode. What do you guys think? @john-livingstonhttps://github.com/john-livingston @Mayuko-Morihttps://github.com/Mayuko-Mori I will also ask Hannu for comments.

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[jpdeleon]

OK, I updated the figures. I removed the transit duration prior on both runs. In the other run with rho star prior, I used Normal(17, 4.5).

The blue lines are references to the values we report in the paper.

[jpdeleon]

Final notebook: https://github.com/jpdeleon/toi1696/blob/main/notebooks/contamination.ipynb