Had I special: The Astronomical Contributions of the Herschel Family

НазваниеHad I special: The Astronomical Contributions of the Herschel Family
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Optical Spectra of the Teacup AGN

Justin Gagne1, D. M. Crenshaw1, W. C. Keel2, T. C. Fischer1
1Georgia State University, 2University of Alabama.

Exhibit Hall

We present optical spectra of the "Teacup AGN", at a redshift of 0.085, discovered in the Sloan Digital Sky Survey (SDSS). The spectra were obtained with the Lowell Observatory 1.8-m Perkins telescope. The SDSS image shows a "handle" of ionized gas extending out to 5'' (8 kpc) away from the nucleus of the galaxy. Our optical spectra reveal a myriad of emission lines resembling those from a typical Seyfert 2 galaxy. We use dereddened emission-line ratios to investigate the physical conditions in the gas and to estimate the luminosity of the hidden AGN.


Multi-wavelength Probes of Obscuration Towards the Narrow Line Region in Seyfert Galaxies

Steven B. Kraemer1, H. Schmitt2, M. Crenshaw3, M. Melendez4, J. Turner5, M. Guainazzi6, R. Mushotzky7
1Catholic University of America, 2NRL, 3Georgia State University, 4Johns Hopkins University, 5UMBC, 6ESA, Spain, 7University of Maryland.

Exhibit Hall

We present a study of reddening and absorption towards the Narrow Line Regions (NLR) in active galactic nuclei (AGN) selected from the Revised Shapley-Ames, 12mu, and Swift/Burst Alert Telescope samples. For the sources in host galaxies with inclinations of b/a > 0.5, we find that mean ratio of [O III] 5007 and [O IV] 28.59mu, is more than a factor of 2 lower in Seyfert 2s than Seyfert 1s. The combination of low [O III]/[O IV] and low [O III] 4363/5007 ratios in Seyfert 2s suggests more extinction of emission from the inner NLR than in Seyfert 1s. Similar column densities of dusty gas can account for the suppression of both [O III] 5007 and [O III] 4363. Also, we find that the X-ray line O VII 22.1A is weaker in Seyfert 2s, consistent with absorption by the same gas that reddens the optical emission. If Seyfert 2 galaxies have similar intrinsic [O III] spatial profiles as Seyfert 1s, the external dusty gas must extend far out along the NLR and, perhaps in the form of nuclear dust spirals.


Determining AGN Feedback Parameters from Seyfert Galaxy Outflows

D. Michael Crenshaw1, S. B. Kraemer2, H. R. Schmitt3, T. C. Fischer1
1Georgia State Univ., 2The Catholic University of America, 3Naval Research Laboratory.

Exhibit Hall

Mass outflows of ionized gas, detected through Hubble Space Telescope observations of blueshifted UV absorption lines and spatially-resolved emission lines, are common in nearby AGN. We review the constraints that these observations place on the structure of AGN winds, and provide estimates of the mass outflow rates and kinematic luminosities needed for AGN feedback models.


Double-Peaked Emission Lines in the Seyfert Galaxy Markarian 78: Mass Outflows from a Single AGN

Travis C. Fischer1, D. M. Crenshaw1, S. B. Kraemer2, H. R. Schmitt3
1Georgia State University, 2The Catholic University of America, 3Naval Research Laboratory.

Exhibit Hall

We present a study of the outflowing ionized gas in the resolved narrow-line region (NLR) of Mrk 78 using observations from Space Telescope Imaging Spectrograph (STIS) and Faint Object Camera (FOC) aboard the Hubble Space Telescope (HST). We determine that the double set of emission lines seen in ground based observations are due to an asymmetric distribution of outflowing gas in the NLR. In successfully fitting a single AGN model to Mrk 78, we show that it is possible to explain double emission lines seen in radial velocity offsets of AGN similar to Mrk 78 without the requirement of dual supermassive black holes.


Quasars in the Extreme UV: Spectral Indices and Potential Emission Lines, and Implications for He II Reionization

David Syphers1, S. Anderson2, W. Zheng3, A. Meiksin4
1University of Colorado, 2University of Washington, 3Johns Hopkins University, 4University of Edinburgh, United Kingdom.

Exhibit Hall

The extreme UV (EUV, <912 A) region of quasar spectra is poorly understood, because the high opacity of intervening hydrogen absorption systems makes it very difficult to observe. In the course of identifying a large number of new sightlines for the He II Gunn-Peterson test, we have amassed an unprecedentedly large collection of quasar spectra covering 250-500 A (rest frame). This allows us to examine emission lines in this largely unexplored region, as well as the average EUV spectral index. This continuum slope is poorly constrained, but vitally important for understanding the ionizing UV background in the IGM, as well as the progress of He II reionization. Our sample complements that of the few other EUV spectral index studies, which mostly extrapolate from longer wavelengths. Cloudy photoionization models of the broad emission line region (BELR) over a high-dimensional parameter space predict detectable He II Ly-alpha emission, with any other lines absent or very weak. Observationally, we find He II Ly-alpha is only rarely present, and sometimes other emission lines are present. We consider a number of possible explanations for weak He II Ly-alpha, including absorption from the IGM and absorption intrinsic to the quasar, and find that although no single explanation suffices, together they may. We find that BELR turbulence is an effective way of increasing the strength of metal lines relative to H and He, and may plausibly explain the presence of EUV metal lines. We offer a few, very tentative identifications of EUV metal lines seen in some spectra. Updates to ongoing HST He II studies will also be briefly described.
We gratefully acknowledge NASA/STScI funding for HST program numbers 10907, 11215, 11982, and 12178.


Variable High Velocity Winds from Broad Absorption Line Quasars

Kenza S. Arraki1, D. Haggard2, S. Anderson3, P. Green4, T. Aldcroft4
1New Mexico State University, 2Northwestern University, 3University of Washington, 4Harvard-Smithsonian Center for Astrophysics.

Exhibit Hall

We study broad absorption line quasars (BALQSOs) because these objects, in particular, probe the high velocity gas ejected by luminous accreting black holes. The variability timescales of BALs can help constrain the size, location, and dynamics of the emitting and absorbing gas near the supermassive black hole. We have obtained multi-epoch spectroscopy of seventeen BALQSOs from the Sloan Digital Sky Survey (SDSS) using the Fred Lawrence Whipple Observatory's 1.5m telescope's FAST Spectrograph. These objects were first identified as BALQSOs in SDSS, observed with Chandra, and then with FAST at 1, 3, 9, 27, and 81 day timescales. Additional observations are acquired for 1 and 2 year cadences. We also obtain a set of non-BAL quasar spectra of similar redshift and luminosity as controls. We identify significant variability and assess its magnitude and frequency in the observed spectra of our BAL QSOs and determine which constraints our investigations can put on the outflows impacting the BAL region.


The Western Radio Lobe of Fornax A: Nature of the X-ray Emission

Electra Panagoulia1, P. Nulsen2, R. Kraft2, L. David2, W. Forman2, C. Jones2, B. McNamara3
1University of Southampton, United Kingdom, 2Harvard Smithsonian Center for Astrophysics, 3Waterloo University, Canada.

Exhibit Hall

An XMM-Newton observation of the western radio lobe of Fornax A has cast doubt on previous interpretations of the X-ray emission as inverse Compton scattered cosmic microwave background radiation. Imaging and spectroscopy both support a thermal origin for at least part of the detected X-ray emission. However, analysis of the XMM-Newton data is complicated by a significant level of background flaring. We will present a new analysis of the X-ray data, paying careful attention to removal of background. Implications of these results for the radio lobe and its group environment will be discussed.


Using Non-linear X-ray Variability to Explore the Core of Active Galaxy 3C 390.3

Sean Quinn1, K. Marshall2
1Rochester Institute of Technology, 2Bucknell University.

Exhibit Hall

Luminous variability of active galaxies is a universal phenomenon; however, there is no universally accepted causal mechanism. This study investigated variability of the broad line radio galaxy 3C 390.3. We concentrated on variability in the X-ray regime (2-10 keV), which is quite rapid-a consequence of the radiation source being proximal to the super massive black hole. Such variability can be explained by accretion disk models; however, there are numerous plausible but physically distinct models. We sought to isolate a particular accretion model which accurately describes the X-ray features for this galaxy. After performing a detailed time series analysis, with a focus on linearity tests, our results imply with high confidence that a non-linear multiplicative model is generating the variability. Given this criterion, we assert that the propagating viscosity fluctuation model is best suited for describing the observed X-ray behavior of this galaxy.
This work was supported by the Bucknell University REU program which is funded by the National Science Foundation.


Fornax A's Western Radio Lobe Composition

Jason J. Kong1, P. E. J. Nulsen2, R. P. Kraft2
1University of California at Berkeley, 2Harvard Smithsonian Astrophysical Observatory.

Exhibit Hall

We present an analysis of the western radio lobe of Fornax A based on an XMM-Newton observation. We find little evidence for the inverse-Compton scattering of the cosmic microwave background as reported previously. The spectra in the energy range of 0.5-5 keV are well fitted by a thermal plus power law model for every spectral region we extracted. With a fixed photon index of 1.68, the X-ray flux density at 1 keV from the power law fit was measured to be < 28 nJy at the 90% confidence level, leading to a lower limit on the magnetic field in this region of 6 micro-Gauss. Our spectral fits suggest that there is hot gas surrounding the radio lobe. A filament of dense, cool gas extends from the central galaxy in the direction of the radio lobe of Fornax A. Spectral fits give a temperature of kT=0.76 keV over the radio lobe and kT=0.32 keV for the cool filament. The thermal emission from the radio lobe region is best explained as emission from a thin shell of shocked gas swept up by the rapidly expanding lobe. This work is supported in part by the NSF REU and DOD ASSURE programs under NSF grant no. 0754568 and by the Smithsonian Institution.


Eclipses of the Inner Accretion Disk in NGC 1365 by Broad Line Region Clouds

Laura Brenneman1, G. Risaliti1, M. Elvis1
1Harvard-Smithsonian Center for Astrophysics.

Exhibit Hall

We present new data obtained from a Suzaku AO5 Long Program observation of NGC 1365, a unique source that has in the past displayed both a prominent, relativistically broadened iron line and evidence for Compton-thin and Compton-thick eclipses of the inner disk region. These eclipse events allow us to constrain the structure and geometry of the inner disk and the intrinsic absorber(s) with unprecedented detail, and enable us to rule definitively on the emission vs. absorption origin of the putative broad iron line in this source.


Evidence Against the Unification of Quasars and Radio Galaxies from a New Sample of Luminous Radio Sources

Todd A. Boroson1

Exhibit Hall

A new sample of high-luminosity extragalactic (0.1 < z < 0.5) radio sources has been constructed using SDSS and three radio surveys: WENSS, NVSS, and FIRST. Initial matching of SDSS with WENSS (325 MHz), including the possibility of sources without radio cores, ensures that the sample is not contaminated by anisotropic radio core emission. This technique finds many more sources than existing catalogs based on SDSS matches with FIRST or NVSS. The resulting list comprises 86 objects in a complete sample having log luminosity density > 26.5 W/Hz at 325 MHz in the rest frame. An additional 26 objects are found that were targeted by SDSS as matches with FIRST or ROSAT sources. Optical properties (luminosities, spectral classification, emission line strengths) and radio properties (spectral index, source morphology, projected linear size) have been measured and tabulated. The distribution of projected linear sizes is particularly interesting; when divided into subsets with and without broad lines, the objects with broad lines (quasars) tend to have larger projected sizes at 1.4 GHz than those without broad lines (radio galaxies). The medians of the size distributions are 200 kpc for the radio galaxies (52 objects) and 350 kpc for the quasars (34 objects). This is different from the classic test by Barthel (1989) from which he argued that radio-loud quasars could be unified with radio galaxies by orientation.


Gamma-Ray Blazar Light Curves at 230 GHz from February 2009-November 2010

Ann E. Wehrle1, A. C. Zook2, M. A. Gurwell3, S. C. Unwin4
1Space Science Institute, 2Pomona College, 3Harvard-Smithsonian Center for Astrophysics, 4Jet Propulsion Laboratory/Caltech.

Exhibit Hall

We present 230 GHz continuum fluxes of blazars on the Fermi LAT Monitored Source List and of several blazars added after the Fermi LAT team reported flaring activity. Our science goal is to determine how and where relativistic charged particles emit synchrotron radiation and also act as scatterers of low energy photons (from jets, dust, the Broad Line Region and the hot corona) up to gamma ray energies.
The data were obtained at approximately two-three week intervals at the Submillimeter Array, beginning in February 2009 and ending in November 2010. This program provides more evenly and frequently sampled data than the Submillimeter Array's ongoing flux density monitoring of quasars that are typically bright in the mm/submm bands, in order to optimally choose quasars for use as interferometric calibration sources (led by M. Gurwell (CfA); see http://sma1.sma.hawaii.edu/callist/callist.html/ ). The resulting light curves may be correlated with Fermi LAT photometry, Swift and RXTE observations, and related ground based monitoring programs. From the comparison, time delays between high and low levels at different bands can be derived. We can also compare the relative amplitudes at millimeter and gamma ray bands of flaring and quiescent levels.
A. Wehrle acknowledges support from the NASA Space Interferometry Mission preparatory science program through JPL Subcontract 1283664 to the Space Science Institute.

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