Classification of Four Swift/BAT Hard X-ray Sources with Bright Optical Counterparts
ATel #5208; J. P. Halpern (Columbia U.)
on 15 Jul 2013; 21:43 UT
Credential Certification: Jules Halpern (jules@astro.columbia.edu)
Subjects: Infra-Red, Optical, X-ray, AGN, Binary
Spectroscopic classifications of three sources from the Swift BAT 70-Month Hard X-ray Survey
(Baumgartner
et al. 2012) were made on 2013 July 4 UT using the MDM Observatory 2.4m Hiltner
telescope with the Boller and Chivens CCD spectrograph.
The wavelength coverage was 3900-7500 Å at 8 Å resolution.
Conditions were partly cloudy. A fourth source was observed
on the 1.3m McGraw-Hill telescope on 2011 December 27.
Swift J0516.3+1928 (z = 0.0187)
The inclined disk galaxy IRAS 05134+1923 at position
(J2000.0) R.A. = 05h 16m 22.7s,
decl. = +19° 27' 11" was identified in the catalog with
this source. Its spectrum from the 1.3m has narrow emission lines of
Hα, [N II] λλ6548,6583, [S II] λλ6716,6731,
and [O III] λλ4959,5007, characteristic of a Seyfert 2
galaxy at z = 0.0187. This redshift measurement resolves
discrepancies in the literature.
Swift J1852.8+3002 (z = 0.057)
The XRT counterpart Swift J185249.5+300428 was studied by
Lutovinov
et al. (2013), who concluded that a 2MASS object to the NW
of a brighter star is its likely counterpart. Although
blended on the DSS,
the pair was resolved in the acquisition
camera at the 2.4m, where three objects within a diameter of 3.6" were
seen. A spectrum of the NW component, 2MASS J185249.43+300427.8,
was isolated using a 1" wide slit, revealing
emission lines and stellar continuum at z = 0.057.
Based on Hα and [N II] λλ6548,6583,
strong [O III] λλ4959,5007, and absence of Hβ,
it can be classified as a type 1.9 Seyfert galaxy because a weak,
broad component of Hα is probably present.
The large X-ray column density
NH = 1.6 × 1022 cm−2
measured by Lutovinov et al. is intrinsic to the low-luminosity,
LX (2−10 keV) ~ 1042 erg s-1,
obscured Seyfert nucleus.
Swift J2124.6+0500 (z = 0)
A variable source in the XRT, with a mean count rate of 0.04 s-1
on 2011 April 3, is coincident with a star
at (J2000.0) R.A. = 21h 24m 12.44s,
decl. = +05° 02' 43.6" having
USNO B1.0 and 2MASS magnitudes B2 = 12.37, R2 = 12.08,
I2 = 11.12, J = 12.245, H = 11.985, and K = 11.806.
Its optical spectrum has broadened emission lines of H, He I, and He II at zero
redshift, as well as the C III/N III λ4640 Bowen blend. Some of the He I
lines are in absorption. The FWHM of Hβ is 1200 km s-1. Equivalent
widths of Hα and Hβ are −10 Å and −2.6 Å, respectively.
He II λ4686 has EW = −4 Å. The
continuum is likely accretion-disk emission. This probable LMXB is located at Galactic
latitude −30.5°, where it is relatively unobscured.
Swift J2157.4−0615 (z = 0.176)
As observed by the XRT on 2010 July 8,
this is a 0.037 counts s-1 source at
(J2000.0) R.A. = 21h 57m 26.7s,
decl. = −06° 10' 19".
It can also be identified with 1RXS J215727.0−061022,
EUVE J2157−06.1
(Lampton et al. 1997),
and the blue stellar object PB 7025
(Berger & Fringant 1984)
located at (J2000.0) RA = 21h 57m 26.78s,
decl. = −06° 10' 17.6". It has
USNO B1.0 and 2MASS magnitudes B1 = 14.25, R1 = 13.94,
I2 = 13.37, J = 14.30, H = 13.78, and K = 12.86.
The spectrum of PB 7025 is that of a broad-lined QSO at z = 0.176.
Optical Spectra
