Dust enshrouded AGNs in 2MASS galaxies?

While I am doing very simple goodness of fit test of 2MASS Ks band selected galaxies using reduced chi^2, I found that some galaxies have very high Sersic index (>8.0), which implies that there might be a point source in the center of galaxies. Inthe BIE meeting, Neal immediately pointed out that it might be from AGN and suggested me to do several tests.

1. Mask the center or add PSF in the model, and see if model gets better. I can also compute Bayes factor to compare two models w and w/o point source in the center. If AGN activity heats the dust, it typically re-radiates its energy peaked around 2 micron(Ks band). See the following paper.

http://adsabs.harvard.edu/abs/2006A&A…453..863P

2. After adjusting the total flux of residual image to zero,  add the residual image to model multiplied by an arbitrary amplification factor and see if the posterior is changed by increasing or decreasing the amplification. This would tell us that how significant the effect of relatively small scale structures(spiral arm, bar, tidal tails) of galaxy is on our parameter inference based on Sersic model. If this is negligible, GALPHAT results will not be biased against non-axis symmetric structure of a galaxy. If not, I have to quantify our criterion of how good the model is and be more careful when interpreting GALPHAT result later.

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~ by ilsangyoon on February 5, 2009.

2 Responses to “Dust enshrouded AGNs in 2MASS galaxies?”

  1. 안녕 일상? astro-ph보고 여기까지 흘러왔어.
    방명록이 없어서 여기다 쓰는데, 이렇게 막 써도 되나 몰라;;
    뭔가 엄청난 걸 만들었구나. 대단하다! 😀
    다들 잘 지내고 있는지? 너도 조만간 졸업하겠네.
    galphat은 조만간 정식으로 릴리즈되면 나도 꼭 써봐야겠고만.

    참, galphat guideline 페이지에 오타 하나 발견했어.
    commend line -> command line (아마도? ^^;)

    암튼 늘 즐겁게 지내고
    언젠가 나중에 보세~

    • 준협, 오랫만이야!
      여기서 이렇게 만나게 되니 반가워. 잘 지내지? 우리도(승우, 현주, 일상) 잘 지내고 있어. 졸업은 해야 하는데 아직 페이퍼도 없고 걱정이 이만저만이 아닐세. 요새 약간 우울모드 라네. 지도교수는 드래프트 언제나 돌려 주려는지…. 이게 2년 삽질의 결과라네. 좀 허무하지 않나? ㅋㅋ
      하여간 잘 지내고 또 보세. 참 오타 알려줘서 고맙네. ^^

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