SWIFT J1644+57

SWIFT J1644+57

서울대학교 물리천문학부 천문학전공 초기우주천체연구단윤용민

Brief introduction Swift J1644+57 was first detected by the

Swift Burst Alert Telescope (BAT) at 12:57:45 UT on 28 March 2011.

The source was assumed to be a gamma-ray burst and was named GRB110328A.

Redshift : 0.35

A. J. Levan et al. (2011)

There are two models to explain this phenomenon.

1. Main sequence star was tidally disrupted by 106 – 107 M◉ BH and its debris accreted into the central BH.

2. White dwarf star was tidally disrupted by ~ 104 M◉ BH.

Time

Flux

Procedure Finding out the fraction of bulge component using HST

images.

CQUEAN(g, r, i, z, Y band) and UKIRT(J, H, K band) data → SED fitting → determining stellar mass of the bulge

fraction.

Finding out the mass of the central black hole.

Analyzing the light curve of 1.5 years period.

M. Limousin et al. (2008)

Flux decay

Current Progress 1. WFC3 UVIS F606W image observed in

2011.12.02

2. WFC3 IR F160W image observed in 2011.12.02

2D fitting by GALFIT to decompose the bulge com-ponent.

1. One component fitting : de Vaucouleurs(Bulge), Exponential(Disk)

2. Two component fitting : Bulge + Disk, Bulge + PSF, Disk + PSF

3. Three component fitting Bulge + Disk + PSF

The models which have small chi-square value and rea-sonable parameters are selected as good fitting models.

Good fitting models of the optical image.

1. Single bulge component model (de Vaucouleurs profile)de Vaucouleurs profile

(Bulge)Magnitude 22.66Effective radius

0.24(arcsec)

Axis ratio 0.97

2. Bulge + PSF Modelde Vaucouleurs profile (Bulge)Magnitude 22.66Effective radius

0.27(arcsec)

Axis ratio 0.98PSF componentMagnitude 26.59

Total magnitude : 22.63

Good fitting models of the IR im-age.

1. Bulge + PSF Modelde Vaucouleurs profile (Bulge)Magnitude 21.50Effective radius

0.15(arcsec)

Axis ratio 0.96PSF componentMagnitude 22.75

Total magnitude : 21.20

2. Bulge + Disk + PSF Modelde Vaucouleurs profile (Bulge)Magnitude 22.08Effective radius

0.11(arcsec)

Axis ratio 0.72Exponential profile (Disk)Magnitude 22.92Effective radius

0.41(arcsec)

Axis ratio 0.82PSF componentMagnitude 22.41

Total magnitude : 21.22

Future work CQUEAN(g, r, i, z, Y band) and UKIRT(J, H, K band)

data → SED fitting → determining stellar mass of the bulge

fraction.

Finding out the mass of the central black hole. → Determining the disrupted star’s identity

A. J. Levan et al. (2011)

Thank you