Hawaii Imaging Fabry-Perot Interferometer Research Articles

A Kinematic Link Between Boxy Bulges, Stellar Bars, and Nuclear Activity in NGC 3079 and NGC 4388

We present direct kinematic evidence for bar streaming in two active galaxies with boxy stellar bulges. The Hawaii Imaging Fabry-Perot Interferometer was used on the Canada-France-Hawaii 3.6-m telescope and the University of Hawaii 2.2-m telescope to derive the two-dimensional velocity field of the line-emitting gas in the disks of the Sc galaxy NGC 3079 and the Sb galaxy NGC 4388. In contrast to previous work based on long-slit data, the detection of the bar potential from the Fabry-Perot data does not rely on the existence of inner Lindblad resonances or strong bar-induced shocks. Simple kinematic models which approximate the intrinsic gas orbits as nonintersecting, inclined elliptical annuli that conserve angular momentum characterize the observed velocity fields. In NGC 3079, bar streaming motions with moderately eccentric orbits (e = b/a approx. 0.7) aligned along PA = 130 deg. intrinsic to the disk (PA = 97 deg. on the sky) are detected out to R(sub b) = 3.6 kpc. The orbits become increasingly circular beyond that radius (e = 1 at R(sub d) approx. = 6 kpc). The best model for NGC 4388 includes highly eccentric orbits (e approx. 0.3) for R(sub) less than or equal to 1.5 kpc which are aligned along PA = 135 deg. intrinsic to the disk (PA = 100 deg. on the sky). The observed spiral arms are produced by having the orbits become increasingly circular from the ends of the bar to the edge of the disk (R(sub d) approx. = 5 kpc), and the intrinsic bar PA shifting from 135 deg. to 90 deg.. Box-shaped bulges in both NGC 3079 and NGC 4388 are confirmed using new near-infrared images to reduce dust obscuration. Morphological analysis of starlight in these galaxies is combined with the gas kinematics derived from the Fabry-Perot spectra to test evolutionary models of stellar bars that involve transitory boxy bulges, and to quantify the importance of such bars in fueling active nuclei. Our data support the evolutionary bar models, but fail to prove convincingly that the stellar bars in NGC 3079 and NGC 4388 directly trigger or sustain the nuclear activity.

Galactic‐Scale Outflow and Supersonic Ram‐Pressure Stripping in the Virgo Cluster Galaxy NGC 4388

The Hawaii Imaging Fabry-Perot Interferometer (HIFI) on the University of Hawaii 2.2 m telescope was used to map the Hα and [O III] λ5007 emission-line profiles across the entire disk of the edge-on Sb galaxy NGC 4388. We confirm a rich complex of highly ionized gas that extends ~4 kpc above the disk of this galaxy. Low-ionization gas associated with star formation is also present in the disk. Evidence for bar streaming is detected in the disk component and is discussed in a companion paper. Nonrotational blueshifted velocities of 50-250 km s-1 are measured in the extraplanar gas northeast of the nucleus. The brighter features in this complex tend to have more blueshifted velocities. A redshifted cloud is also detected 2 kpc southwest of the nucleus. The velocity field of the extraplanar gas of NGC 4388 appears to be unaffected by the inferred supersonic (Mach number M ≈ 3) motion of this galaxy through the ICM of the Virgo cluster. We argue that this is because the galaxy and the high-|z| gas lie behind a Mach cone with opening angle ~80°. The shocked ICM that flows near the galaxy has a velocity of ~500 km s-1 and exerts insufficient ram pressure on the extraplanar gas to perturb its kinematics. We consider several explanations of the velocity field of the extraplanar gas. Velocities, especially blueshifted velocities on the north of the galaxy, are best explained as a bipolar outflow that is tilted by >12° from the normal to the disk. The observed offset between the extraplanar gas and the radio structure may be due to buoyancy or refractive bending by density gradients in the halo gas. Velocity substructure in the outflowing gas also suggests an interaction with ambient halo gas.

The interstellar disk-halo connection in the spiral galaxy NGC 3079

We discuss the morphology and excitation of ionized gas in the nearby Sc galaxy NGC 3079. The almost edge-on orientation is ideal for studying the vertical structure of the gaseous disk, and especially the diffuse ionized medium (DIM) found between the bright H II regions. We used the Hawaii Imaging Fabry-Perot Interferometer (HIFI) to map 150,000 H-alpha + (N II) lambda lambda 6548, 6583 emission-line profiles across the entire disk, with resolution 70 km/s at subarcsecond steps, down to a flux level of approximately 10(exp -17) ergs/s/sq cm (EM approximately equal to 4 cm(exp -6) pc). The DIM contributes approximately 30% of the total disk H-alpha emission within a radius of 10 kpc. The DIM has broader emission lines and larger (N II) H-alpha flux ratios than the adjacent H II regions. Within a radius of 5 kpc, we find that the X-shaped filaments reported in previous studies emerge from the inner (R approximately equal to 1.5 kpc) disk, and rise more than 4 kpc above the disk plane. The morphology, kinematics, and excitation of the filaments suggest that they form a biconic interface between the undisturbed disk gas, and gas entrained in the wide-angle outflow. The DIM beyond 5 kpc radius is more vertically extended than the thick ionized disk detected in our Galaxy and in a few nearby edge-on systems. After correcting for dust, the vertical profile of this DIM has an exponential scale height of about 1.1 kpc, similar to that of the H I disk. The (N II) lambda 6538/H-alpha flux ratio of the DIM increases monotonically with vertical height, reaching unity for absolute value of z greater than or approximately equal to 2.5 kpc. The flux required to keep the DIM ionized at R = 8 kpc is similar to that near the solar circle of our Galaxy. Highly dilute radiation from O stars in the galactic plane probably maintains the DIM. The total mass of the DIM is of order 10(exp 8) - 10(exp 9) solar mass, representing less than 1% of the total dynamical mass of NGC 3079. Mechanical energy from intense star formation in the disk probably lifts the DIM above the disk. The several bubbles and filaments within 1 kpc of the disk plane is direct evidence for gas flow between the disk and halo.

HIFI Survey of Emission-Line Galaxies: recent Results on the Nuclear Superbubble of NGC 3079

AbstractThe Hawaii Imaging Fabry-Perot Interferometer (HIFI) was used to produce a large data cube of the edge-on SBc galaxy NGC 3079 covering Hα + [NII] λλ6548, 6583. The complete two-dimensional coverage of the Fabry-Perot data allowed us to derive the general flow pattern of the nuclear gas that constitutes the energetic superbubble.

Observations of Extragalactic Objects with the Hawaii Imaging Fabry-Perot Interferometer (HIFI)

AbstractImaging Fabry-Perot interferometers have a particularly useful role to play in studies of the extended regions of anomalous emission in active galaxies. It becomes possible to study the velocity and excitation structure of warm gas with full coverage of large fields. Observations and modeling of several good examples of transient activity will be described as a way of demonstrating the power of an operational facility.

The nuclear superbubble of NGC 3079

view Abstract Citations (172) References (105) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Nuclear Superbubble of NGC 3079 Veilleux, S. ; Cecil, G. ; Bland-Hawthorn, J. ; Tully, R. B. ; Filippenko, A. V. ; Sargent, W. L. W. Abstract We have used the Hawaii Imaging Fabry-Perot Interferometer (HIFI) at the CFH 3.6 m telescope to map Hα+[NII] λλ6548, 6583 emission-line profiles across the entire edge-on, nearby SBc galaxy NGC 3079, with resolution 70 km s^-1^ and subarsecond sampling. Blue and red long-slit spectra were obtained with the Double Spectrograph on the Palomar 5 meter telescope to provide additional emission-line diagnostics. A spectacular, line emitting bubble of diameter 13" (~1.1 kpc) is observed immediately east of the nucleus. Its unusual gaseous excitation (e.g., [N II] λ6583/Hα > 1) suggests that shocks are important. Extremely violent gas motions that range over 2000 km s^- 1^ are detected across the bubble and diametrically opposite on the west side of the nucleus. Nonrotational motions are also found in the inner galaxy disk. The complete spatial and spectral sampling of the emission-line profiles allows us to constrain the general flow pattern of the gas in the line-emitting bubble. An ovoidal bubble, inflated from the nucleus with monotonically increasing velocities (V is proportional to R^n^ with 2 < n < 3) and inclined ~3^deg^ from the plane of the sky, provides a good first-order fit to its velocity field. A total ionized mass and kinetic energy of ~1 x 10^7^/N_e_ M_sun_ and ~2 x 10^56^/N_e_ ergs, respectively, are involved in this outflow. Although the [S II] density in the bubble is only weakly constrained, we find no convincing evidence anywhere in the bubble (even near the nucleus) for the [S II] density to be above the low-density limit (N_e_ ~ 125 cm^-3^). The radial density gradient previously reported in this galaxy is not confirmed, so the [S II] density profile cannot be used to find the size of the energy injection zone in this object. The Balmer decrements in the nucleus and the brighter regions of the outflow show a steep decrease in reddening away from the galaxy plane. The outflow mass is similar to, but the kinetic energy may be 10 times larger than, the superwinds in the Seyfert galaxy NGC 1068 and the starburst galaxy M82. Therefore, the superbubble of NGC 3079 is the most powerful example known of a windblown bubble, and an excellent laboratory to study wind dynamics. The dimensions and energies of the bubble imply that it is likely to be in the blowout phase and partially ruptured. The predicted rate of kinetic energy output from the central starburst appears sufficient to power most of this outflow. It is possible that a central active galactic nucleus also contributes to the outflow. Publication: The Astrophysical Journal Pub Date: September 1994 DOI: 10.1086/174624 Bibcode: 1994ApJ...433...48V Keywords: Astronomical Photometry; Astronomical Spectroscopy; Atomic Spectra; Bubbles; Gas Dynamics; H Alpha Line; Interstellar Matter; Seyfert Galaxies; Stellar Winds; Fabry-Perot Interferometers; Interstellar Gas; Kinematics; Spectrographs; Spectrophotometry; Ultraviolet Astronomy; Visible Spectrum; Astronomy; GALAXIES: INDIVIDUAL NGC NUMBER: NGC 3079; GALAXIES: SEYFERT; ISM: BUBBLES; GALAXIES: KINEMATICS AND DYNAMICS; GALAXIES: STRUCTURE full text sources ADS | data products SIMBAD (9) NED (1)

The nuclear superbubble of NGC 3079

We have used the Hawaii Imaging Fabry-Perot Interferometer (HIFI) at the CFH 3.6 m telescope to map H-alpha + (N II) lambda-lambda 6548, 6583 emission-line profiles across the entire edge-on, nearby SBc galaxy NGC 3079, with resolution 70 km/s and subarcsecond sampling. Blue and red long-slit spectra were obtained with the Double Spectrograph on the Palomar 5 meter telescope to provide additional emission-line diagnostics. A spectacular, line emitting bubble of diameter 13 sec (approximately 1.1 kpc) is observed immediately east of the nucleus. Its unusual gaseous excitation (e.g., (N II) lambda(6583)/H-alpha greater than 1) suggests that shocks are important. Extremely violent gas motions that range over 2000 km/s are detected across the bubble and diametrically opposite on the west side of the nucleus. Nonrotational motions are also found in the inner galaxy disk. The superbubble of NGC 3079 is the most powerful example known of a wind-blown bubble, and an excellent laboratory to study wind dynamics. The dimensions and energies of the bubble imply that is likely to be in the blowout phase and partially ruptured. The predicted rate of kinetic energy output from the central starburst appears sufficient to power most of this outflow. It is possible that a central active galactic nucleus also contributes to the outflow.

The braided jets in the spiral galaxy NGC 4258

The Hawaii Imaging Fabry-Perot Interferometer have been used to synthesize 44000 Hα and [N II] emission-line profiles at velocity resolution 68 km/s FWHM across the disk of the nearby Seyfert/LINER galaxy NGC 4258, including the prominent «four-branched jet» that extends to 10 and 5 kpc radii in the radio continuum and optical emission lines, respectively. A long-slit spectrum, which includes the emission lines Hα, [N II] λλ6548, 6583 and [S II] λλ6717, 6731, has also been obtained along the jets

DIFFUSE IONIZED MEDIUM IN NGC 1068

ABSTRACT (~10 kpc; ~135"), diffuse ionized medium (DIM) recently detected in the nearby, luminous Seyfert galaxy NGC 1068. The DIM phase was recognized from spectrophotometric Hα and [N II] λλ6548,6584 line emission maps obtained with the Hawaii Imaging Fabry-Perot Interferometer (HIFI). We demonstrate that the Hot equivalent-width distribution, when combined with the [N II] λ6584/Hα line ratio distribution, permits a clean separation of the DIM from the adjacent H II region population. We summarize the main reasons that lead us to believe the DIM is photoexcited predominantly by scattered light from the active nucleus rather than the extended stellar population.

Imaging spectrophotometry of ionized gas in NGC 1068. II - Global ionization of the inner disk

Spectrophotometric observations with the Hawaii Imaging Fabry-Perot Interferometer of the Hα and [N II] λλ6548, 6584 lines has detected a diffuse ionized medium pervading the inner ∼10 kpc diameter disk of the nearby, luminous Seyfert galaxy NGC 1068. The physics and dynamics of this energetic gas are distinct from the population of adjacent disk H II regions. The [N II] and CO line dispersions indicate that the diffuse ionized medium is distended to a much larger scale height than the molecular disk.

Deep Fabry-Perot Imaging of NGC 6240: Kinematic Evidence for Merging Galaxies

AbstractWe have observed the superluminous, infrared galaxy NGC 6240 (z = 0.025) at Ha with the Hawaii Imaging Fabry-Perot Interferometer (HIFI – Bland and Tully 1989). During the past decade, observational evidence from all wavebands indicates that the unusual appearance of NGC 6240 has resulted from a collision between two gas-rich systems, a view which is supported by our spectrophotometnc data. However, the origin of the enormous infrared luminosity (4 × 1011 L0) detected by IRAS remains highly controversial, where opinions differ on the relative roles of large-scale shocks, massive star formation or a buried “active” nucleus. These mechanisms are discussed in the light of our Fabry-Perot observations.

The Hawaii imaging Fabry-Perot interferometer (HIFI)

view Abstract Citations (74) References (17) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Hawaii imaging Fabry-Perot interferometer (HIFI) Bland, Jonathan ; Tully, R. Brent Abstract At Mauna Kea Observatory, optical studies of bright, nearby galaxies have been conducted using Fabry-Perot systems on both the University of Hawaii 2.2-m and Canada-France-Hawaii 3.6-m telescopes. These instruments provide high kinematic resolution for a field of view as much as 10 arcmin at subarcsecond increments matched to the seeing disk above the site. The present approach differs from that of the highly successful TAURUS systems (Taylor and Atherton 1980) in the use of a large free-spectral-range etalon with high finesse and CCD at the image plane. CCDs afford certain advantages over photon-counting detectors for two-dimensional, kinematic, and spectrophotometric studies. The geometric integrity of the CCD produces a clean Airy surface and bypasses the optoelectronic distortions of image intensifiers. The high quantum efficiency and linearity over a wide dynamic range in intensity proved to be essential in recent studies of extended narrowline regions, the results of which are summarized. A major advantage afforded by photon-counting systems is the ability to scan rapidly in wavelength, while CCDs are presently limited by detector readout noise. As the readout noise of CCDs approaches a few electrons, the readout time will provide the limitation to rapid scanning. Publication: The Astronomical Journal Pub Date: August 1989 DOI: 10.1086/115173 Bibcode: 1989AJ.....98..723B Keywords: Astronomical Observatories; Fabry-Perot Interferometers; Astronomical Photometry; Calibrating; Charge Coupled Devices; Etalons; Galaxies; Hawaii; Imaging Spectrometers; Instrumentation and Photography full text sources ADS | data products NED (1)

Imaging Spectrophotometry of the Narrow-Line Region of NGC 1068

The NLR of the Sy 2 galaxy NGC 1068 has been studied with the Hawaii Imaging Fabry-Perot Interferometer on the U. Hawaii 2.2m telescope. Kinematics of [N II] λλ6548,6583 and Ha were mapped across the inner 1′-diameter by obtaining monochromatic images (65 km s−1 FWHM) with a low-noise (5e− RMS) CCD at sub-arcsecond spatial and ∼90 km s−1 effective velocity resolution. Our complete coverage of this nearby (14 Mpc; 1″ = 75 pc), spatially extended NLR allows unprecedented study of the interaction of a collimated radio “jet” (Wilson &amp; Ulvestad 1983) with the warm ionized component of the ambient interstellar medium.

The Large-Scale Activity in NGC 1068

While NGC 1068 has received much attention in recent years, little is known of the large-scale dynamics and physical state of the ionized gas in this nearby Seyfert galaxy and, in particular, its connection with the nuclear activity. We have used the Hawaii Imaging Fabry-Perot Interferometer (HIFI) at the CFHT to obtain detailed spectrophotometry at 65 kms−1 resolution (FWHM) over the Hα and neighbouring [N II] lines. The final maps are derived from 100 000 fits to spectra taken at 0.4″ increments over a 200″ field-of-view. (A higher resolution study which concentrates on the circumnuclear, optical emission and its relation to the radio jet is presented at this conference by Cecil &amp; Bland.)