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Articles 1 - 11 of 11
Full-Text Articles in Physical Sciences and Mathematics
The Event Horizon Of M87, Avery E. Broderick, Ramesh Narayan, John Kormendy, Eric S. Perlman, Marcia J. Rieke, Sheperd S. Doleman
The Event Horizon Of M87, Avery E. Broderick, Ramesh Narayan, John Kormendy, Eric S. Perlman, Marcia J. Rieke, Sheperd S. Doleman
Aerospace, Physics, and Space Science Faculty Publications
The 6 x 10⁹ M⊙ supermassive black hole at the center of the giant elliptical galaxy M87 powers a relativistic jet. Observations at millimeter wavelengths with the Event Horizon Telescope have localized the emission from the base of this jet to angular scales comparable to the putative black hole horizon. The jet might be powered directly by an accretion disk or by electromagnetic extraction of the rotational energy of the black hole. However, even the latter mechanism requires a confining thick accretion disk to maintain the required magnetic flux near the black hole. Therefore, regardless of the jet mechanism, the …
The Differences In The Torus Geometry Between Hidden And Non-Hidden Broad Line Active Galactic Nuclei, Kohei Ichikawa, Eric S. Perlman
The Differences In The Torus Geometry Between Hidden And Non-Hidden Broad Line Active Galactic Nuclei, Kohei Ichikawa, Eric S. Perlman
Aerospace, Physics, and Space Science Faculty Publications
We present results from the fitting of infrared (IR) spectral energy distributions of 21 active galactic nuclei (AGNs) with clumpy torus models. We compiled high spatial resolution (∼0.3–0.7 arcsec) mid-IR (MIR) N-band spectroscopy, Q-band imaging, and nuclear near- and MIR photometry from the literature. Combining these nuclear near- and MIR observations, far-IR photometry, and clumpy torus models enables us to put constraints on the torus properties and geometry. We divide the sample into three types according to the broad line region (BLR) properties: type-1s, type-2s with scattered or hidden broad line region (HBLR) previously observed, and type-2s without any published …
The Nuclear Near-Infrared Spectral Properties Of Nearby Galaxies, Rachel E. Mason, Eric S. Perlman
The Nuclear Near-Infrared Spectral Properties Of Nearby Galaxies, Rachel E. Mason, Eric S. Perlman
Aerospace, Physics, and Space Science Faculty Publications
We present spectra of the nuclear regions of 50 nearby (D = 1-92 Mpc, median = 20 Mpc) galaxies of morphological types E to Sm. The spectra, obtained with the Gemini Near-IR Spectrograph on the Gemini North telescope, cover a wavelength range of approximately 0.85-2.5 μm at R ∼ 1300-1800. There is evidence that most of the galaxies host an active galactic nucleus (AGN), but the range of AGN luminosities (log (L2 - 10 kev [erg s-1]) = 37.0-43.2) in the sample means that the spectra display a wide variety of features. Some nuclei, especially the Seyferts, exhibit a rich …
Polarized Mid-Infrared Synchrotron Emission In The Core Of Cygnus A, Enrique López Rodríguez, Eric S. Perlman
Polarized Mid-Infrared Synchrotron Emission In The Core Of Cygnus A, Enrique López Rodríguez, Eric S. Perlman
Aerospace, Physics, and Space Science Faculty Publications
We present high-angular (∼0". 4) resolution mid-infrared (MIR) polarimetric observations in the 8.7μm and 11.6μm filters of Cygnus A using CanariCam on the 10.4 m Gran Telescopio CANARIAS. A highly polarized nucleus is observed with a degree of polarization of 11% ±3% and 12% ±3% and a position angle of polarization of 27◦ ±8◦ and 35◦ ± 8◦ in a 0.".38 (∼380 pc) aperture for each filter. The observed rising of the polarized flux density with increasing wavelength is consistent with synchrotron radiation from the parsec-scale jet close to the core of Cygnus A. Based on our polarization model, the …
Reconstructing The Stellar Mass Distributions Of Galaxies Using S4g Irac 3.6 And 4.5 Μm Images. Ii. The Conversion From Light To Mass, Sharon E. Meidt, Trisha F. Mizusawa
Reconstructing The Stellar Mass Distributions Of Galaxies Using S4g Irac 3.6 And 4.5 Μm Images. Ii. The Conversion From Light To Mass, Sharon E. Meidt, Trisha F. Mizusawa
Aerospace, Physics, and Space Science Faculty Publications
We present a new approach for estimating the 3.6 μm stellar mass-to- light (M/L) ratio Υ3.6 in terms of the [3.6]-[4.5] colors of old stellar populations. Our approach avoids several of the largest sources of uncertainty in existing techniques using population synthesis models. By focusing on mid-IR wavelengths, we gain a virtually dust extinction-free tracer of the old stars, avoiding the need to adopt a dust model to correctly interpret optical or optical/near-IR colors normally leveraged to assign the mass-to-light ratio Υ. By calibrating a new relation between near-IR and mid-IR colors of giant stars observed in GLIMPSE we also …
Subaru Spectroscopy And Spectral Modeling Of Cygnus A, Matthew J. Merlo, Eric S. Perlman, Robert Nikutta, Christopher Packham, Moshe Elitzur, Masatoshi Imanishi, Nancy A. Levenson, James T. Radomski, Itziar Aretxaga
Subaru Spectroscopy And Spectral Modeling Of Cygnus A, Matthew J. Merlo, Eric S. Perlman, Robert Nikutta, Christopher Packham, Moshe Elitzur, Masatoshi Imanishi, Nancy A. Levenson, James T. Radomski, Itziar Aretxaga
Aerospace, Physics, and Space Science Faculty Publications
We present high angular resolution (∼0.″5) MIR spectra of the powerful radio galaxy, Cygnus A (Cyg A), obtained with the Subaru telescope. The overall shape of the spectra agree with previous high angular resolution MIR observations, as well as previous Spitzer spectra. Our spectra, both on and off nucleus, show a deep silicate absorption feature. The absorption feature can be modeled with a blackbody obscured by cold dust or a clumpy torus. The deep silicate feature is best fit by a simple model of a screened blackbody, suggesting that foreground absorption plays a significant, if not dominant, role in shaping …
Uncovering The Deeply Embedded Active Galactic Nucleus Activity In The Nuclear Regions Of The Interacting Galaxy Arp 299, A Alonso-Herrero, Eric S. Perlman
Uncovering The Deeply Embedded Active Galactic Nucleus Activity In The Nuclear Regions Of The Interacting Galaxy Arp 299, A Alonso-Herrero, Eric S. Perlman
Aerospace, Physics, and Space Science Faculty Publications
We present mid-infrared (MIR) 8-13 μm spectroscopy of the nuclear regions of the interacting galaxy Arp 299 (IC 694+NGC 3690) obtained with CanariCam (CC) on the 10.4 m Gran Telescopio Canarias (GTC). The high angular resolution (∼0.″3-0.″6) of the data allows us to probe nuclear physical scales between 60 and 120 pc, which is a factor of 10 improvement over previous MIR spectroscopic observations of this system. The GTC/CC spectroscopy displays evidence of deeply embedded active galactic nucleus (AGN) activity in both nuclei. The GTC/CC nuclear spectrum of NGC 3690/Arp 299-B1 can be explained as emission from AGN-heated dust in …
Nicmos Polarimetry Of "Polar-Scattered" Seyfert 1 Galaxies, Daniel P. Batcheldor, Andrew Edward Robinson, David J. Axon, Stuart Young, S Quinn, James E. Smith, James H. Hough, David M. Alexander
Nicmos Polarimetry Of "Polar-Scattered" Seyfert 1 Galaxies, Daniel P. Batcheldor, Andrew Edward Robinson, David J. Axon, Stuart Young, S Quinn, James E. Smith, James H. Hough, David M. Alexander
Aerospace, Physics, and Space Science Faculty Publications
The nuclei of Seyfert 1 galaxies exhibit a range of optical polarization characteristics that can be understood in terms of two scattering regions producing orthogonal polarizations: an extended polar scattering region (PSR) and a compact equatorial scattering region (ESR), located within the circum-nuclear torus. Here we present NICMOS 2.0 μm imaging polarimetry of six "polar-scattered" Seyfert 1 (S1) galaxies, in which the PSR dominates the optical polarization. The unresolved nucleus (<058) is significantly polarized in only three objects, but five of the six exhibit polarization in a 058-15 circum-nuclear annulus. In Fairall 51 and ESO 323-G077, the polarization position angle at 2 μm (θ2 μm) is consistent with the average for the optical spectrum(θv), implying that the nuclear polarization is dominated by polar scattering at both wavelengths. The same is probably true for NGC3227. In both NGC 4593 and Mrk 766, there is a large difference between θ2 μm and θv off-nucleus, where polar scattering is expected to dominate. This may be due to contamination by interstellar polarization in NGC4593, but there is no clear explanation in the case of the strongly polarized Mrk766. Lastly, in Mrk1239, a large change (60°) in θ2 μm between the nucleus and the annulus indicates that the unresolved nucleus and its immediate surroundings have different polarization states at 2μm, which we attribute to the ESR and PSR, respectively. A further implication is that the source of the scattered 2 μm emission in the unresolved nucleus is the accretion disk, rather than torus hot dust emission.
Hubble Space Telescope Observations Of The Quasar Pks 0637-752: Equipartition Electron-Proton Jet From The Most Complete Spectral Coverage To Date, Kushal T. Mehta, Markos Georganopoulos, Eric S. Perlman, Charles A. Padgett, George Chartas
Hubble Space Telescope Observations Of The Quasar Pks 0637-752: Equipartition Electron-Proton Jet From The Most Complete Spectral Coverage To Date, Kushal T. Mehta, Markos Georganopoulos, Eric S. Perlman, Charles A. Padgett, George Chartas
Aerospace, Physics, and Space Science Faculty Publications
We present new Near-Infrared Camera and Multi-Object Spectrometer and attitude control system observations of the quasar jet PKS 0637-752, and we use them, together with existing multiwavelength observations, to produce the most complete spectral coverage of the source to date. We explore the implications of these observations in the context of models for the jet X-ray emission. By relaxing the assumption of equipartition, we undertake an exhaustive study of the parameter space for external Compton off the cosmic microwave background (CMB) (EC/CMB) model. We find that the multiwavelength observations exclude a magnetic-field-dominated jet. Using the method proposed by Georganopoulos et …
The Mid-Infrared Emission Of M87, Eric S. Perlman, Rachel E. Mason, Christopher C. Packham, Nancy A. Levenson, Moshe Elitzur, Justin J. Schaefer, Masatoshi Imanishi, William B. Sparks, James T. Radomski
The Mid-Infrared Emission Of M87, Eric S. Perlman, Rachel E. Mason, Christopher C. Packham, Nancy A. Levenson, Moshe Elitzur, Justin J. Schaefer, Masatoshi Imanishi, William B. Sparks, James T. Radomski
Aerospace, Physics, and Space Science Faculty Publications
We discuss Subaru and Spitzer Space Telescope imaging and spectroscopy of M87 in the mid-infrared (mid-IR) from 5 to 35 μm. These observations allow us to investigate mid-IR emission mechanisms in the core of M87 and to establish that the flaring, variable jet component HST-1 is not a major contributor to the mid-IR flux. The Spitzer data include a high signal-to-noise ratio 15-35 μm spectrum of the knot A/B complex in the jet, which is consistent with synchrotron emission. However, a synchrotron model cannot account for the observed nuclear spectrum, even when contributions from the jet, necessary due to the …
Gemini Mid-Ir Polarimetry Of Ngc 1068: Polarized Structures Around The Nucleus, Christopher C. Packham, Stuart Young, Scott E. Fisher, Kevin M. Volk, Rachel E. Mason, James H. Hough, Patrick F. Roche, Moshe Elitzur, James T. Radomski, Eric S. Perlman
Gemini Mid-Ir Polarimetry Of Ngc 1068: Polarized Structures Around The Nucleus, Christopher C. Packham, Stuart Young, Scott E. Fisher, Kevin M. Volk, Rachel E. Mason, James H. Hough, Patrick F. Roche, Moshe Elitzur, James T. Radomski, Eric S. Perlman
Aerospace, Physics, and Space Science Faculty Publications
We present diffraction-limited, 10 μm imaging polarimetry data for the central regions of the archetypal Seyfert active galactic nucleus NGC 1068. The position angle of polarization is consistent with three dominant polarizing mechanisms. We identify three distinct regions of polarization: (1) north of the nucleus, arising from aligned dust in the narrow emission line region, (2) south, east, and west of the nucleus, consistent with dust being channeled toward the central engine, and (3) a central minimum of polarization consistent with a compact (≤22 pc) torus. These observations provide continuity between the geometrically and optically thick torus and the host …