A Spitzer Spectrum of the Exoplanet HD 189733b

We report on the measurement of the 7.5-14.7 micron spectrum for the transiting extrasolar giant planet HD 189733b using the Infrared Spectrograph on the Spitzer Space Telescope. Though the observations comprise only 12 hours of telescope time, the continuum is well measured and has a flux ranging from 0.6 mJy to 1.8 mJy over the wavelength range, or 0.49 +/- 0.02% of the flux of the parent star. The variation in the measured fractional flux is very nearly flat over the entire wavelength range and shows no indication of significant absorption by water or methane, in contrast with the predictions of most atmospheric models. Models with strong day/night differences appear to be disfavored by the data, suggesting that heat redistribution to the night side of the planet is highly efficient.Comment: 12 pages, 3 figures, accepted for publication in the Astrophysical Journal Letter

A view of the narrow-line region in the infrared: active galactic nuclei with resolved fine-structure lines in the Spitzer archive

We queried the Spitzer archive for high-resolution observations with the Infrared Spectrograph of optically selected active galactic nuclei (AGN) for the purpose of identifying sources with resolved fine-structure lines that would enable studies of the narrow-line region (NLR) at mid-infrared wavelengths. By combining 298 Spitzer spectra with 6 Infrared Space Observatory spectra, we present kinematic information of the NLR for 81 z<=0.3 AGN. We used the [NeV], [OIV], [NeIII], and [SIV] lines, whose fluxes correlate well with each other, to probe gas photoionized by the AGN. We found that the widths of the lines are, on average, increasing with the ionization potential of the species that emit them. No correlation of the line width with the critical density of the corresponding transition was found. The velocity dispersion of the gas, sigma, is systematically higher than that of the stars, sigma_*, in the AGN host galaxy, and it scales with the mass of the central black hole, M_BH. Further correlations between the line widths and luminosities L, and between L and M_BH, are suggestive of a three dimensional plane connecting log(M_BH) to a linear combination of log(sigma) and log(L). Such a plane can be understood within the context of gas motions that are driven by AGN feedback mechanisms, or virialized gas motions with a power-law dependence of the NLR radius on the AGN luminosity. The M_BH estimates obtained for 35 type 2 AGN from this plane are consistent with those obtained from the M_BH-sigma_* relation.Comment: ApJ, revised to match the print versio

The Unusual Near-Infrared Morphology of the Radio Loud Quasar 4C+09.17

Near-infrared images of the luminous, high redshift (z=2.1108) radio loud quasar 4C+09.17 reveal a complex structure. The quasar (K=15.76 mag) is surrounded by three "companion" objects having 17.9< K < 20.2 mag at radii of 1.7" < r < 2.9", as well as bright, diffuse emission. The brightest companion has a redshift of z=0.8384 (Lehnert & Becker 1997) and its optical-infrared colors (Lehnert et al. 1997) are consistent with a late-type spiral galaxy at this redshift with a luminosity of about 2L*. This object is likely the galaxy responsible for the strongest MgII absorption line system seen in the spectrum of 4C+09.17 by Barthel et al. (1990). Redshifts are not available for the remaining two companions. The red colors of the second brightest companion appear most consistent with a high redshift star-forming galaxy at z > 1.5. If this object is at the redshift of 4C +09.17 it has a luminosity of about 7L*. The faintest companion has colors which are unlike those expected from either a spiral or an E/S0 galaxy at any redshift associated with the 4C+09.17 system. Since this object lies along the same direction as the radio jet/lobe of 4C+09.17, as well as the extended Ly-alpha emission mapped by Heckman et al. (1991) we suggest that this component can be explained as a combination of strong line emission and scattered QSO light. The resolved, diffuse emission surrounding 4C+09.17 is bright, K~17.0 mag, and about one magnitude redder in J-K than the quasar. If this emission is starlight, a very luminous elliptical host galaxy is implied for 4C+09.17. Scattered and reddened AGN light, emission line gas, and flux from absorbing galaxies along the line of sight may all contribute to this emission.Comment: plain LaTex with 4 postscript figures, MNRAS, accepte

Luminous Infrared Galaxies With the Submillimeter Array. III. The Dense Kiloparsec Molecular Concentrations of Arp 299

We have used high resolution (~2.3") observations of the local (D = 46 Mpc) luminous infrared galaxy Arp 299 to map out the physical properties of the molecular gas which provides the fuel for its extreme star formation activity. The 12CO J=3-2, 12CO J=2-1 and 13CO J=2-1 lines were observed with the Submillimeter Array and the short spacings of the 12CO J=2-1 and J=3-2 observations have been recovered using James Clerk Maxwell Telescope single dish observations. We use the radiative transfer code RADEX to estimate the physical properties (density, column density and temperature) of the different regions in this system. The RADEX solutions of the two galaxy nuclei, IC 694 and NGC 3690, are consistent with a wide range of gas components, from warm moderately dense gas with T_{kin} > 30 K and n(H_{2}) ~ 0.3 - 3 x 10^{3} cm^{-3} to cold dense gas with T_{kin} ~ 10-30 K and n(H_{2}) > 3 x 10^{3} cm^{-3}. The overlap region is shown to have a better constrained solution with T_{\rm{kin}}$ ~ 10-50 K and n(H_{2}) ~ 1-30 x 10^{3} cm^{-3}. We estimate the gas masses and star formation rates of each region in order to derive molecular gas depletion times. The depletion times of all regions (20-60 Myr) are found to be about 2 orders of magnitude lower than those of normal spiral galaxies. This rapid depletion time can probably be explained by a high fraction of dense gas on kiloparsec scales in Arp 299. We estimate the CO-to-H_{2} factor, \alpha_{co} to be 0.4 \pm 0.3 (3 x 10^{-4}/ x_{CO}) M_{sol} (K km s^{-1} pc^{2})^{-1} for the overlap region. This value agrees well with values determined previously for more advanced merger systems.Comment: 24 pages, 4 figures, ApJ accepte

Near Infrared Observations of IRAS 09104+4109

Near infrared imaging and grism spectroscopy of the high luminosity infrared bright galaxy IRAS 09104+4109 have been obtained with the W. M. Keck Telescope. The imaging shows 6 “knots” of emission projected against the extended stellar envelope of the cD galaxy thought to be the source of the large far infrared luminosity. The luminosities of the knots are consistent with the bulges of galaxies accreting onto the central galaxy. In addition, there are 11 companion galaxies seen at radii of 40-150 kpc from the cD nucleus. These objects have colors in the range R—K~ 3.5±0.5 mag, J-H~0.9±0.2 mag H-K ~0.7±0.2 mag, which are consistent with galaxies at a redshift of 0.4. The companion galaxies have luminosities comparable to or less than the characteristic luminosity (L^*) of field galaxies. While the central cD galaxy is identified with the luminous infrared source, it appears to be a quiescent, radio-quiet galaxy, showing no evidence from its near infrared colors for a highly reddened nucleus as seen in other infrared luminous galaxies. The grism spectroscopy shows forbidden lines of low ionization stages of sulfer, iron, and oxygen, as well as hydrogen recombination lines and a strong line of neutral helium. A visual extinction of Av—2 mag is derived to the narrow line region surrounding the galaxy nucleus, based on the line ratios [S II]1.03 µm/0.407 µm and Pδ/Hβ. The near infrared spectrum is consistent with the optical classification of this system being a Seyfert 2 nucleus