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1. Space Telescope and Optical Reverberation Mapping Project. XII. Broad-Line Region Modeling of NGC 5548

Author

Williams, P. R., Pancoast, A., Treu, T., Brewer, B. J., Peterson, B. M., Barth, A. J., Malkan, M. A., De Rosa, G., Horne, Keith, Kriss, G. A., Arav, N., Bentz, M. C., Cackett, E. M., Bontà, E. Dalla, Dehghanian, M., Done, C., Ferland, G. J., Grier, C. J., Kaastra, J., Kara, E., Kochanek, C. S., Mathur, S., Mehdipour, M., Pogge, R. W., Proga, D., Vestergaard, M., Waters, T., Adams, S. M., Anderson, M. D., Arévalo, P., Beatty, T. G., Bennert, V. N., Bigley, A., Bisogni, S., Borman, G. A., Boroson, T. A., Bottorff, M. C., Brandt, W. N., Breeveld, A. A., Brotherton, M., Brown, J. E., Brown, J. S., Canalizo, G., Carini, M. T., Clubb, K. I., Comerford, J. M., Corsini, E. M., Crenshaw, D. M., Croft, S., Croxall, K. V., Deason, A. J., De Lorenzo-Cáceres, A., Denney, K. D., Dietrich, M., Edelson, R., Efimova, N. V., Ely, J., Evans, P. A., Fausnaugh, M. M., Filippenko, A. V., Flatland, K., Fox, O. D., Gardner, E., Gates, E. L., Gehrels, N., Geier, S., Gelbord, J. M., Gonzalez, L., Gorjian, V., Greene, J. E., Grupe, D., Gupta, A., Hall, P. B., Henderson, C. B., Hicks, S., Holmbeck, E., Holoien, T. W. -S., Hutchison, T., Im, M., Jensen, J. J., Johnson, C. A., Joner, M. D., Jones, J., Kaspi, S., Kelly, P. L., Kennea, J. A., Kim, M., Kim, S., Kim, S. C., King, A., Klimanov, S. A., Knigge, C., Krongold, Y., Lau, M. W., Lee, J. C., Leonard, D. C., Li, Miao, Lira, P., Lochhaas, C., Ma, Zhiyuan, Manne-Nicholas, E. R., MacInnis, F., Mauerhan, J. C., McGurk, R., Hardy, I. M. Mc, Montuori, C., Morelli, L., Mosquera, A., Mudd, D., Müller-Sánchez, F., Nazarov, S. V., Norris, R. P., Nousek, J. A., Nguyen, M. L., Ochner, P., Okhmat, D. N., Papadakis, I., Parks, J. R., Pei, L., Penny, M. T., Pizzella, A., Poleski, R., Pott, J. -U., Rafter, S. E., Rix, H. -W., Runnoe, J., Saylor, D. A., Schimoia, J. S., Scott, B., Sergeev, S. G., Shappee, B. J., Shivvers, I., Siegel, M., Simonian, G. V., Siviero, A., Skielboe, A., Somers, G., Spencer, M., Starkey, D., Stevens, D. J., Sung, H. -I., Tayar, J., Tejos, N., Turner, C. S., Uttley, P., Van Saders, J., Vaughan, S. A., Vican, L., Villanueva Jr., S., Villforth, C., Weiss, Y., Woo, J. -H., Yan, H., Young, S., Yuk, H., Zheng, W., Zhu, W., and Zu, Y.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

We present geometric and dynamical modeling of the broad line region for the multi-wavelength reverberation mapping campaign focused on NGC 5548 in 2014. The dataset includes photometric and spectroscopic monitoring in the optical and ultraviolet, covering the H$\beta$, C IV, and Ly$\alpha$ broad emission lines. We find an extended disk-like H$\beta$ BLR with a mixture of near-circular and outflowing gas trajectories, while the C IV and Ly$\alpha$ BLRs are much less extended and resemble shell-like structures. There is clear radial structure in the BLR, with C IV and Ly$\alpha$ emission arising at smaller radii than the H$\beta$ emission. Using the three lines, we make three independent black hole mass measurements, all of which are consistent. Combining these results gives a joint inference of $\log_{10}(M_{\rm BH}/M_\odot) = 7.64^{+0.21}_{-0.18}$. We examine the effect of using the $V$ band instead of the UV continuum light curve on the results and find a size difference that is consistent with the measured UV-optical time lag, but the other structural and kinematic parameters remain unchanged, suggesting that the $V$ band is a suitable proxy for the ionizing continuum when exploring the BLR structure and kinematics. Finally, we compare the H$\beta$ results to similar models of data obtained in 2008 when the AGN was at a lower luminosity state. We find that the size of the emitting region increased during this time period, but the geometry and black hole mass remain unchanged, which confirms that the BLR kinematics suitably gauge the gravitational field of the central black hole., Comment: 26 pages, 19 figures, 1 table, accepted for publication in ApJ

Published
2020
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2. VERITAS Discovery of VHE Emission from the Radio Galaxy 3C 264: A Multi-Wavelength Study

Author

Archer, A., Benbow, W., Bird, R., Brill, A., Buchovecky, M., Buckley, J. H., Carini, M. T., Christiansen, J. L., Chromey, A. J., Daniel, M. K., Errando, M., Falcone, A., Feng, Q., Fortin, P., Fortson, L., Furniss, A., Gent, A., Georganopoulos, M., Gillanders, G. H., Giuri, C., Gueta, O., Hanna, D., Hassan, T., Hervet, O., Holder, J., Hughes, G., Humensky, T. B., Kaaret, P., Kertzman, M., Kieda, D., Krennrich, F., Lang, M. J., Lin, T. T. Y., Lister, M. L., Lundy, M., Maier, G., Meyer, E. T., Moriarty, P., Mukherjee, R., Nieto, D., Nievas-Rosillo, M., O'Brien, S., Ong, R. A., Pfrang, K., Pohl, M., Prado, R. R., Pueschel, E., Quinn, J., Ragan, K., Ramirez, K., Reynolds, P. T., Ribeiro, D., Richards, G. T., Roache, E., Rulten, C., Ryan, J. L., Sadun, A., Santander, M., Scott, S. S., Sembroski, G. H., Shahinyan, K., Shang, R., Stevenson, B., Vassiliev, V. V., Wakely, S. P., Weinstein, A., Wilcox, P., Wilhelm, A., Williams, D. A., and Williamson, T. J

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

The radio source 3C 264, hosted by the giant elliptical galaxy NGC 3862, was observed with VERITAS between February 2017 and May 2019. These deep observations resulted in the discovery of very-high-energy (VHE; E $>100$ GeV) $\gamma$-ray emission from this active galaxy. An analysis of $\sim$57 hours of quality-selected live time yields a detection at the position of the source, corresponding to a statistical significance of 7.8 standard deviations above background. The observed VHE flux is variable on monthly time scales, with an elevated flux seen in 2018 observations. The VHE emission during this elevated state is well-characterized by a power-law spectrum with a photon index $\Gamma = 2.20 \pm 0.27$ and flux F($>315$ GeV) = ($7.6\pm 1.2_{\mathrm stat} \pm 2.3_{\mathrm syst})\times 10^{-13}$ cm$^{-2}$ s$^{-1}$, or approximately 0.7% of the Crab Nebula flux above the same threshold. 3C 264 ($z = 0.0217$) is the most distant radio galaxy detected at VHE, and the elevated state is thought to be similar to that of the famously outbursting jet in M 87. Consequently, extensive contemporaneous multi-wavelength data were acquired in 2018 at the time of the VHE high state. An analysis of these data, including VLBA, VLA, HST, Chandra and Swift observations in addition to the VERITAS data, is presented, along with a discussion of the resulting spectral energy distribution., Comment: 19 pages, 11 figures, Accepted for publication in Astrophysical Journal

Published
2020
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3. Space Telescope and Optical Reverberation Mapping Project. IX. Velocity-Delay Maps for Broad Emission Lines in NGC 5548

Author

Horne, Keith, De Rosa, G., Peterson, B. M., Barth, A. J., Ely, J., Fausnaugh, M. M., Kriss, G. A., Pei, L., Adams, S. M., Anderson, M. D., Arevalo, P., Beatty, T G., Bennert, V. N., Bentz, M. C., Bigley, A., Bisogni, S., Borman, G. A., Boroson, T. A., Bottorff, M. C., Brandt, W. N., Breeveld, A. A., Brotherton, M., Brown, J. E., Brown, J. S., Cackett, E. M., Canalizo, G., Carini, M. T., Clubb, K. I., Comerford, J. M., Corsini, E. M., Crenshaw, D. M., Croft, S., Croxall, K. V., Bonta, E. Dalla, Deason, A. J., Dehghanian, M., De Lorenzo-Caceres, A., Denney, K. D., Dietrich, M., Done, C., Edelson, R., Efimova, N. V., Eracleous, M., Evans, P. A., Ferland, G. J., Filippenko, A. V., Flatland, K., Fox, O. D., Gardner, E., Gates, E. L., Gehrels, N., Geier, S., Gelbord, J. M., Goad, M. R., Gonzalez, L., Gorjian, V., Greene, J. E., Grier, C. J., Grupe, D., Gupta, A., Hall, P. B., Henderson, C. B., Hicks, S., Holmbeck, E., Holoien, T. W. -S., Hutchison, T., Im, M., Jensen, J. J., Johnson, C. A., Joner, M. D., Jones, J., Kaastra, J., Kaspi, S., Kelly, P. L., Kennea, J. A., Kim, M., Kim, S., Kim, S. C., King, A., Klimanov, S. A., Kochanek, C. S., Korista, K. T., Krongold, Y., Lau, M. W., Lee, J. C., Leonard, D. C., Li, Miao, Lira, P., Lochhaas, C., Ma, Zhiyuan, MacInnis, F., Malkan, M. A., Manne-Nicholas, E. R., Mathur, S., Mauerhan, J. C., McGurk, R., Hardy, I. M. Mc, Montuori, C., Morelli, L., Mosquera, A., Mudd, D., Mueller-Sanchez, F., Nazarov, S. V., Netzer, H., Norris, R. P., Nousek, J. A., Nguyen, M. L., Ochner, P., Okhmat, D. N., Pancoast, A., Papadakis, I., Parks, J. R., Penny, M. T., Pizzella, A., Pogge, R. W., Poleski, R., Pott, J. -U., Proga, D., Rafter, S. E., Rix, H. -W., Runnoe, J., Saylor, D. A., Schimoia, J. S., Schnuelle, K., Scott, B., Sergeev, S. G., Shappee, B. J., Shivvers, I., Siegel, M., Simonian, G. V., Siviero, A., Skielboe, A., Somers, G., Spencer, M., Starkey, D., Stevens, D. J., Strauss, M. A., Sung, H. -I., Tayar, J., Teems, K. G., Tejos, N., Treu, T., Turner, C. S., Uttley, P., Van Saders, J ., Vestergaard, M., Vican, L., Villanueva Jr, S., Villforth, C., Weiss, Y., Woo, J. -H., Yan, H., Young, S., Yuk, H., Zakamska, N. L., Zheng, W., Zhu, W., and Zu, Y.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

We report velocity-delay maps for prominent broad emission lines, Ly_alpha, CIV, HeII and H_beta, in the spectrum of NGC5548. The emission-line responses inhabit the interior of a virial envelope. The velocity-delay maps reveal stratified ionization structure. The HeII response inside 5-10 light-days has a broad single-peaked velocity profile. The Ly_alpha, CIV, and H_beta responses peak inside 10 light-days, extend outside 20 light-days, and exhibit a velocity profile with two peaks separated by 5000 km/s in the 10 to 20 light-day delay range. The velocity-delay maps show that the M-shaped lag vs velocity structure found in previous cross-correlation analysis is the signature of a Keplerian disk with a well-defined outer edge at R=20 light-days. The outer wings of the M arise from the virial envelope, and the U-shaped interior of the M is the lower half of an ellipse in the velocity-delay plane. The far-side response is weaker than that from the near side, so that we see clearly the lower half, but only faintly the upper half, of the velocity--delay ellipse. The delay tau=(R/c)(1-sin(i))=5 light-days at line center is from the near edge of the inclined ring, giving the inclination i=45 deg. A black hole mass of M=7x10^7 Msun is consistent with the velocity-delay structure. A barber-pole pattern with stripes moving from red to blue across the CIV and possibly Ly_alpha line profiles suggests the presence of azimuthal structure rotating around the far side of the broad-line region and may be the signature of precession or orbital motion of structures in the inner disk. Further HST observations of NGC 5548 over a multi-year timespan but with a cadence of perhaps 10 days rather than 1 day could help to clarify the nature of this new AGN phenomenon., Comment: 19 pages, 9 figures, ApJ in press

Published
2020
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4. The Great Markarian 421 Flare of February 2010: Multiwavelength variability and correlation studies

Author

Abeysekara, A. U., Benbow, W., Bird, R., Brill, A., Brose, R., Buchovecky, M., Buckley, J. H., Christiansen, J. L., Chromey, A. J., Daniel, M. K., Dumm, J., Falcone, A., Feng, Q., Finley, J. P., Fortson, L., Furniss, A., Galante, N., Gent, A., Gillanders, G. H., Giuri, C., Gueta, O., Hassan, T., Hervet, O., Holder, J., Hughes, G., Humensky, T. B., Johnson, C. A., Kaaret, P., Kar, P., Kelley-Hoskins, N., Kertzman, M., Kieda, D., Krause, M., Krennrich, F., Kumar, S., Lang, M. J., Moriarty, P., Mukherjee, R., Nelson, T., Nieto, D., Nievas-Rosillo, M., O'Brien, S., Ong, R. A., Otte, A. N., Park, N., Petrashyk, A., Pichel, A., Pohl, M., Prado, R. R., Pueschel, E., Quinn, J., Ragan, K., Reynolds, P. T., Richards, G. T., Roache, E., Rovero, A. C., Rulten, C., Sadeh, I., Santander, M., Sembroski, G. H., Shahinyan, K., Stevenson, B., Sushch, I., Tyler, J., Vassiliev, V. V., Wakely, S. P., Weinstein, A., Wells, R. M., Wilcox, P., Wilhelm, A., Williams, D. A., Zitzer, B., Acciari, V. A., Ansoldi, S., Antonelli, L. A., Engels, A. Arbet, Baack, D., Babić, A., Banerjee, B., de Almeida, U. Barres, Barrio, J. A., González, J. Becerra, Bednarek, W., Bellizzi, L., Bernardini, E., Berti, A., Besenrieder, J., Bhattacharyya, W., Bigongiari, C., Biland, A., Blanch, O., Bonnoli, G., Busetto, G., Carosi, R., Ceribella, G., Chai, Y., Cikota, S., Colak, S. M., Colin, U., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., D'Elia, V., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., Delfino, M., Delgado, J., Di Pierro, F., Espiñera, E. Do Souto, Prester, D. Dominis, Dorner, D., Doro, M., Einecke, S., Elsaesser, D., Ramazani, V. Fallah, Fattorini, A., Fernández-Barral, A., Ferrara, G., Fidalgo, D., Foffano, L., Fonseca, M. V., Font, L., Fruck, C., Galindo, D., Gallozzi, S., López, R. J. García, Garczarczyk, M., Gasparyan, S., Gaug, M., Godinović, N., Green, D., Guberman, D., Hadasch, D., Hahn, A., Herrera, J., Hoang, J., Hrupec, D., Inoue, S., Ishio, K., Iwamura, Y., Kubo, H., Kushida, J., Lamastra, A., Lelas, D., Leone, F., Lindfors, E., Lombardi, S., Longo, F., López, M., López-Coto, R., López-Oramas, A., Fraga, B. Machado de Oliveira, Maggio, C., Majumdar, P., Makariev, M., Mallamaci, M., Maneva, G., Manganaro, M., Mannheim, K., Maraschi, L., Mariotti, M., Martínez, M., Masuda, S., Mazin, D., Miceli, D., Minev, M., Miranda, J. M., Mirzoyan, R., Molina, E., Moralejo, A., Morcuende, D., Moreno, V., Moretti, E., Munar-Adrover, P., Neustroev, V., Niedzwiecki, A., Rosillo, M. Nievas, Nigro, C., Nilsson, K., Ninci, D., Nishijima, K., Noda, K., Nogués, L., Nöthe, M., Paiano, S., Palacio, J., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Peñil, P., Peresano, M., Persic, M., Moroni, P. G. Prada, Prandini, E., Puljak, I., Rhode, W., Ribó, M., Rico, J., Righi, C., Rugliancich, A., Saha, L., Sahakyan, N., Saito, T., Satalecka, K., Schweizer, T., Sitarek, J., Šnidarić, I., Sobczynska, D., Somero, A., Stamerra, A., Strom, D., Strzys, M., Sun, S., Surić, T., Tavecchio, F., Temnikov, P., Terzić, T., Teshima, M., Torres-Albà, N., Tsujimoto, S., van Scherpenberg, J., Vanzo, G., Acosta, M. Vazquez, Vovk, I., Will, M., Zarić, D., Aller, H. D., Aller, M. F., Carini, M. T., Horan, D., Jordan, B., Jorstad, Svetlana G., Kurtanidze, O. M., Kurtanidze, S. O., Lähteenmäki, A., Larionov, V. M., Larionova, E. G., Madejski, G., Marscher, Alan P., Max-Moerbeck, W., Moody, J. Ward, Morozova, D. A., Nikolashvili, M. G., Raiteri, C. M., Readhead, A. C. S., Richards, J. L., Sadun, Alberto C., Sakamoto, T., Sigua, L. A., Smith, P. S., Talvikki, H., Tammi, J., Tornikoski, M., Troitsky, I. S., and Villata, M.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We report on variability and correlation studies using multiwavelength observations of the blazar Mrk 421 during the month of February, 2010 when an extraordinary flare reaching a level of $\sim$27~Crab Units above 1~TeV was measured in very-high-energy (VHE) $\gamma$-rays with the VERITAS observatory. This is the highest flux state for Mrk 421 ever observed in VHE $\gamma$-rays. Data are analyzed from a coordinated campaign across multiple instruments including VHE $\gamma$-ray (VERITAS, MAGIC), high-energy (HE) $\gamma$-ray (Fermi-LAT), X-ray (Swift}, RXTE, MAXI), optical (including the GASP-WEBT collaboration and polarization data) and radio (Mets\"ahovi, OVRO, UMRAO). Light curves are produced spanning multiple days before and after the peak of the VHE flare, including over several flare `decline' epochs. The main flare statistics allow 2-minute time bins to be constructed in both the VHE and optical bands enabling a cross-correlation analysis that shows evidence for an optical lag of $\sim$25-55 minutes, the first time-lagged correlation between these bands reported on such short timescales. Limits on the Doppler factor ($\delta \gtrsim 33$) and the size of the emission region ($ \delta^{-1}R_B \lesssim 3.8\times 10^{13}\,\,\mbox{cm}$) are obtained from the fast variability observed by VERITAS during the main flare. Analysis of 10-minute-binned VHE and X-ray data over the decline epochs shows an extraordinary range of behavior in the flux-flux relationship: from linear to quadratic to lack of correlation to anti-correlation. Taken together, these detailed observations of an unprecedented flare seen in Mrk 421 are difficult to explain by the classic single-zone synchrotron self-Compton model., Comment: 41 pages including 3 appendices, 13 figures; version accepted to Astrophysical Journal

Published
2020
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5. Space Telescope and Optical Reverberation Mapping Project. VIII. Time Variability of Emission and Absorption in NGC 5548 Based on Modeling the Ultraviolet Spectrum

Author

Kriss, G. A., De Rosa, G., Ely, J., Peterson, B. M., Kaastra, J., Mehdipour, M., Ferland, G. J., Dehghanian, M., Mathur, S., Edelson, R., Korista, K. T., Arav, N., Barth, A. J., Bentz, M. C., Brandt, W. N., Crenshaw, D. M., Bontà, E. Dalla, Denney, K. D., Done, C., Eracleous, M., Fausnaugh, M. M., Gardner, E., Goad, M. R., Grier, C. J., Horne, Keith, Kochanek, C. S., Mchardy, I. M., Netzer, H., Pancoast, A., Pei, L., Pogge, R. W., Proga, D., Silva, C., Tejos, N., Vestergaard, M., Adams, S. M., Anderson, M. D., Arévalo, P., Beatty, T G., Behar, E., Bennert, V. N., Bianchi, S., Bigley, A., Bisogni, S., Boissay-Malaquin, R., Borman, G. A., Bottorff, M. C., Breeveld, A. A., Brotherton, M., Brown, J. E., Brown, J. S., Cackett, E. M., Canalizo, G., Cappi, M., Carini, M. T., Clubb, K. I., Comerford, J. M., Coker, C. T., Corsini, E. M., Costantini, E., Croft, S., Croxall, K. V., Deason, A. J., De Lorenzo-Cáceres, A., De Marco, B., Dietrich, M., Di Gesu, L., Ebrero, J., Evans, P. A., Filippenko, A. V., Flatland, K., Gates, E. L., Gehrels, N., Geier, Z S., Gelbord, J. M., Gonzalez, L., Gorjian, V., Grupe, D., Gupta, A., Hall, P. B., Henderson, C. B., Hicks, S., Holmbeck, E., Holoien, T. W. -S., Hutchison, T. A., Im, M., Jensen, J. J., Johnson, C. A., Joner, M. D., Kaspi, S., Kelly, B. C., Kelly, P. L., Kennea, J. A., Kim, M., Kim, S. C., Kim, S. Y., King, A., Klimanov, S. A., Krongold, Y., Lau, M. W., Lee, J. C., Leonard, D. C., Li, Miao, Lira, P., Lochhaas, C., Ma, Zhiyuan, Macinnis, F., Malkan, M. A., Manne-Nicholas, E. R., Matt, G., Mauerhan, J. C., Mcgurk, R., Montuori, C., Morelli, L., Mosquera, A., Mudd, D., Müller-Sánchez, F., Nazarov, S. V., Norris, R. P., Nousek, J. A., Nguyen, M. L., Ochner, P., Okhmat, D. N., Paltani, S., Parks, J. R., Pinto, C., Pizzella, A., Poleski, R., Ponti, G., Pott, J. -U., Rafter, S. E., Rix, H. -W., Runnoe, J., Saylor, D. A., Schimoia, J. S., Schnülle, K., Scott, B., Sergeev, S. G., Shappee, B. J., Shivvers, I., Siegel, M., Simonian, G. V., Siviero, A., Skielboe, A., Somers, G., Spencer, M., Starkey, D., Stevens, D. J., Sung, H. -I., Tayar, J., Teems, K. G., Treu, T., Turner, C. S., Uttley, P., Van Saders, J ., Vican, L., Villforth, C., Villanueva Jr., S., Walton, D. J., Waters, T., Weiss, Y., Woo, J. -H., Yan, H., Yuk, H., Zheng, W., Zhu, W., and Zu, Y.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

We model the ultraviolet spectra of the Seyfert 1 galaxy NGC~5548 obtained with the Hubble Space Telescope during the 6-month reverberation-mapping campaign in 2014. Our model of the emission from NGC 5548 corrects for overlying absorption and deblends the individual emission lines. Using the modeled spectra, we measure the response to continuum variations for the deblended and absorption-corrected individual broad emission lines, the velocity-dependent profiles of Ly$\alpha$ and C IV, and the narrow and broad intrinsic absorption features. We find that the time lags for the corrected emission lines are comparable to those for the original data. The velocity-binned lag profiles of Ly$\alpha$ and C IV have a double-peaked structure indicative of a truncated Keplerian disk. The narrow absorption lines show delayed response to continuum variations corresponding to recombination in gas with a density of $\sim 10^5~\rm cm^{-3}$. The high-ionization narrow absorption lines decorrelate from continuum variations during the same period as the broad emission lines. Analyzing the response of these absorption lines during this period shows that the ionizing flux is diminished in strength relative to the far-ultraviolet continuum. The broad absorption lines associated with the X-ray obscurer decrease in strength during this same time interval. The appearance of X-ray obscuration in $\sim\,2012$ corresponds with an increase in the luminosity of NGC 5548 following an extended low state. We suggest that the obscurer is a disk wind triggered by the brightening of NGC 5548 following the decrease in size of the broad-line region during the preceding low-luminosity state., Comment: 50 pages, 30 figures, uses aastex62.cls. Accepted for publication in ApJ, 07/06/2019. High-level products page in MAST will go live after 7/15/2019. Replaced Figure 4 on 7/12/2019 to be more red/green color-blind friendly

Published
2019
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6. Space Telescope and Optical Reverberation Mapping Project. VII. Understanding the UV anomaly in NGC 5548 with X-Ray Spectroscopy

Author

Mathur, S., Gupta, A., Page, K., Pogge, R. W., Krongold, Y., Goad, M. R., Adams, S. M., Anderson, M. D., Arevalo, P., Barth, A. J., Bazhaw, C., Beatty, T. G., Bentz, M. C., Bigley, A., Bisogni, S., Borman, G. A., Boroson, T. A., Bottorff, M. C., Brandt, W. N., Breeveld, A. A., Brown, J. E., Brown, J. S., Cackett, E. M., Canalizo, G., Carini, M. T., Clubb, K. I., Comerford, J. M., Coker, C. T., Corsini, E. M., Crenshaw, D. M., Croft, S., Croxall, K. V., Bonta, E. Dalla, Deason, A. J., Denney, K. D., De Lorenzo-Caceres, A., De Rosa, G., Dietrich, M., Edelson, R., Ely, J., Eracleous, M., Evans, P. A., Fausnaugh, M. M., Ferland, G. J., Filippenko, A. V., Flatland, K., Fox, O. D., Gates, E. L., Gehrels, N., Geier, S., Gelbord, J. M., Gorjian, V., Greene, J. E., Grier, C. J., Grupe, D., Hall, P. B., Henderson, C. B., Hicks, S., Holmbeck, E., Holoien, T. W. -S., Horenstein, D., Horne, Keith, Hutchison, T., Im, M., Jensen, J. J., Johnson, C. A., Joner, M. D., Jones, J., Kaastra, J., Kaspi, S., Kelly, B. C., Kelly, P. L., Kennea, J. A., Kim, M., Kim, S., Kim, S. C., King, A., Klimanov, S. A., Kochanek, C. S., Korista, K. T., Kriss, G. A., Lau, M. W., Lee, J. C., Leonard, D. C., Li, M., Lira, P., Ma, Z., MacInnis, F., Manne-Nicholas, E. R., Malkan, M. A., Mauerhan, J. C., McGurk, R., McHardy, I. M., Montouri, C., Morelli, L., Mosquera, A., Mudd, D., Muller-Sanchez, F., Musso, R., Nazarov, S. V., Netzer, H., Nguyen, M. L., Norris, R. P., Nousek, J. A., Ochner, P., Okhmat, D. N., Ou-Yang, B., Pancoast, A., Papadakis, I., Parks, J. R., Pei, L., Peterson, B. M., Pizzella, A., Poleski, R., Pott, J. -U., Rafter, S. E., Rix, H. -W., Runnoe, J., Saylor, D. A., Schimoia, J. S., Schnülle, K., Sergeev, S. G., Shappee, B. J., Shivvers, I., Siegel, M., Simonian, G. V., Siviero, A., Skielboe, A., Somers, G., Spencer, M., Starkey, D., Stevens, D. J., Sung, H. -I., Tayar, J., Tejos, N., Turner, C. S., Uttley, P., Van Saders, J., Vestergaard, M., Vican, L., VillanuevaJr., S., Villforth, C., Weiss, Y., Woo, J. -H., Yan, H., Young, S., Yuk, H., Zheng, W., Zhu, W., and Zu, Y.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

During the Space Telescope and Optical Reverberation Mapping Project (STORM) observations of NGC 5548, the continuum and emission-line variability became de-correlated during the second half of the 6-month long observing campaign. Here we present Swift and Chandra X-ray spectra of NGC 5548 obtained as a part of the campaign. The Swift spectra show that excess flux (relative to a power-law continuum) in the soft X-ray band appears before the start of the anomalous emission-line behavior, peaks during the period of the anomaly, and then declines. This is a model-independent result suggesting that the soft excess is related to the anomaly. We divide the Swift data into on- and off-anomaly spectra to characterize the soft excess via spectral fitting. The cause of the spectral differences is likely due to a change in the intrinsic spectrum rather than being due to variable obscuration or partial covering. The Chandra spectra have lower signal-to-noise ratios, but are consistent with Swift data. Our preferred model of the soft excess is emission from an optically thick, warm Comptonizing corona, the effective optical depth of which increases during the anomaly. This model simultaneously explains all the three observations: the UV emission line flux decrease, the soft-excess increase, and the emission line anomaly., Comment: ApJ in press. Replaced with the accepted version

Published
2017
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7. Space Telescope and Optical Reverberation Mapping Project. V. Optical Spectroscopic Campaign and Emission-Line Analysis for NGC 5548

Author

Pei, L., Fausnaugh, M. M., Barth, A. J., Peterson, B. M., Bentz, M. C., De Rosa, G., Denney, K. D., Goad, M. R., Kochanek, C. S., Korista, K. T., Kriss, G. A., Pogge, R. W., Bennert, V. N., Brotherton, M., Clubb, K. I., Bontà, E. Dalla, Filippenko, A. V., Greene, J. E., Grier, C. J., Vestergaard, M., Zheng, W., Adams, Scott M., Beatty, Thomas G., Bigley, A., Brown, Jacob E., Brown, Jonathan S., Canalizo, G., Comerford, J. M., Coker, Carl T., Corsini, E. M., Croft, S., Croxall, K. V., Deason, A. J., Eracleous, Michael, Fox, O. D., Gates, E. L., Henderson, C. B., Holmbeck, E., Holoien, T. W. -S., Jensen, J. J., Johnson, C. A., Kelly, P. L., Kim, S., King, A., Lau, M. W., Li, Miao, Lochhaas, Cassandra, Ma, Zhiyuan, Manne-Nicholas, E. R., Mauerhan, J. C., Malkan, M. A., McGurk, R., Morelli, L., Mosquera, Ana, Mudd, Dale, Sanchez, F. Muller, Nguyen, M. L., Ochner, P., Ou-Yang, B., Pancoast, A., Penny, Matthew T., Pizzella, A., Poleski, Radosław, Runnoe, Jessie, Scott, B., Schimoia, Jaderson S., Shappee, B. J., Shivvers, I., Simonian, Gregory V., Siviero, A., Somers, Garrett, Stevens, Daniel J., Strauss, M. A., Tayar, Jamie, Tejos, N., Treu, T., Van Saders, J., Vican, L., Villanueva Jr., S., Yuk, H., Zakamska, N. L., Zhu, W., Anderson, M. D., Arévalo, P., Bazhaw, C., Bisogni, S., Borman, G. A., Bottorff, M. C., Brandt, W. N., Breeveld, A. A., Cackett, E. M., Carini, M. T., Crenshaw, D. M., De Lorenzo-Cáceres, A., Dietrich, M., Edelson, R., Efimova, N. V., Ely, J., Evans, P. A., Ferland, G. J., Flatland, K., Gehrels, N., Geier, S., Gelbord, J. M., Grupe, D., Gupta, A., Hall, P. B., Hicks, S., Horenstein, D., Horne, Keith, Hutchison, T., Im, M., Joner, M. D., Jones, J., Kaastra, J., Kaspi, S., Kelly, B. C., Kennea, J. A., Kim, M., Kim, S. C., Klimanov, S. A., Lee, J. C., Leonard, D. C., Lira, P., MacInnis, F., Mathur, S., McHardy, I. M., Montouri, C., Musso, R., Nazarov, S. V., Netzer, H., Norris, R. P., Nousek, J. A., Okhmat, D. N., Papadakis, I., Parks, J. R., Pott, J. -U., Rafter, S. E., Rix, H. -W., Saylor, D. A., Schnülle, K., Sergeev, S. G., Siegel, M., Skielboe, A., Spencer, M., Starkey, D., Sung, H. -I., Teems, K. G., Turner, C. S., Uttley, P., Villforth, C., Weiss, Y., Woo, J. -H., Yan, H., Young, S., and Zu, Y.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

We present the results of an optical spectroscopic monitoring program targeting NGC 5548 as part of a larger multi-wavelength reverberation mapping campaign. The campaign spanned six months and achieved an almost daily cadence with observations from five ground-based telescopes. The H$\beta$ and He II $\lambda$4686 broad emission-line light curves lag that of the 5100 $\AA$ optical continuum by $4.17^{+0.36}_{-0.36}$ days and $0.79^{+0.35}_{-0.34}$ days, respectively. The H$\beta$ lag relative to the 1158 $\AA$ ultraviolet continuum light curve measured by the Hubble Space Telescope is roughly $\sim$50% longer than that measured against the optical continuum, and the lag difference is consistent with the observed lag between the optical and ultraviolet continua. This suggests that the characteristic radius of the broad-line region is $\sim$50% larger than the value inferred from optical data alone. We also measured velocity-resolved emission-line lags for H$\beta$ and found a complex velocity-lag structure with shorter lags in the line wings, indicative of a broad-line region dominated by Keplerian motion. The responses of both the H$\beta$ and He II $\lambda$4686 emission lines to the driving continuum changed significantly halfway through the campaign, a phenomenon also observed for C IV, Ly $\alpha$, He II(+O III]), and Si IV(+O IV]) during the same monitoring period. Finally, given the optical luminosity of NGC 5548 during our campaign, the measured H$\beta$ lag is a factor of five shorter than the expected value implied by the $R_\mathrm{BLR} - L_\mathrm{AGN}$ relation based on the past behavior of NGC 5548., Comment: 22 pages, 13 figures, accepted to ApJ

Published
2017
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8. Space Telescope and Optical Reverberation Mapping Project VI: reverberating Disk Models for NGC 5548

Author

Starkey, D., Horne, Keith, Fausnaugh, M. M., Peterson, B. M., Bentz, M. C., Kochanek, C. S., Denney, K. D., Edelson, R., Goad, M. R., De Rosa, G., Anderson, M. D., Arevalo, P., Barth, A. J., Bazhaw, C., Borman, G. A., Boroson, T. A., Bottorff, M. C., Brandt, W. N., Breeveld, A. A., Cackett, E. M., Carini, M. T., Croxall, K. V., Crenshaw, D. M., Bonta, E. Dalla, De Lorenzo-Caceres, A., Dietrich, M., Efimova, N. V., Ely, J., Evans, P. A., Filippenko, A. V., Flatland, K., Gehrels, N., Geier, S., Gelbord, J. M., Gonzalez, L., Gorjian, V., Grier, C. J., Grupe, D., Hall, P. B., Hicks, S., Horenstein, D., Hutchison, T., Im, M., Jensen, J. J., Joner, M. D., Jones, J., Kaastra, J., Kaspi, S., Kelly, B. C., Kennea, J. A., Kim, S. C., Kim, M., Klimanov, S. A., Korista, K. T., Kriss, G. A., Lee, J. C., Leonard, D. C., Lira, P., MacInnis, F., Manne-Nicholas, E. R., Mathur, S., McHardy, I. M., Montouri, C., Musso, R., Nazarov, S. V., Norris, R. P., Nousek, J. A., Okhmat, D. N., Pancoast, A., Parks, J. R., Pei, L., Pogge, R. W., Pott, J. -U., Rafter, S. E., Rix, H. W., Saylor, D. A., Schimoia, J. S., Schnulle, K., Sergeev, S. G., Siegel, M. H., Spencer, M., Sung, H. -I., Teems, K. G., Turner, C. S., Uttley, P., Vestergaard, M., Villforth, C., Weiss, Y., Woo, J. -H., Yan, H., Young, S., Zheng, W., and Zu, Y.

Subjects
Astrophysics - Astrophysics of Galaxies, Astrophysics - High Energy Astrophysical Phenomena
Abstract

We conduct a multiwavelength continuum variability study of the Seyfert 1 galaxy NGC 5548 to investigate the temperature structure of its accretion disk. The 19 overlapping continuum light curves (1158 to 9157 angstroms) combine simultaneous HST , Swift , and ground-based observations over a 180 day period from 2014 January to July. Light-curve variability is interpreted as the reverberation response of the accretion disk to irradiation by a central time-varying point source. Our model yields the disk inclination, i, temperature T1 at 1 light day from the black hole, and a temperature-radius slope, alpha. We also infer the driving light curve and find that it correlates poorly with both the hard and soft X-ray light curves, suggesting that the X-rays alone may not drive the ultraviolet and optical variability over the observing period. We also decompose the light curves into bright, faint, and mean accretion-disk spectra. These spectra lie below that expected for a standard blackbody accretion disk accreting at L/LEdd = 0.1, Comment: V2: Oops wrong title! V1: Accepted for publication in ApJ, 20 Pages, 11 Figures

Published
2016
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9. Space Telescope and Optical Reverberation Mapping Project. IV. Anomalous behavior of the broad ultraviolet emission lines in NGC 5548

Author

Goad, M. R., Korista, K. T., De Rosa, G., Kriss, G. A., Edelson, R., Barth, A. J., Ferland, G. J., Kochanek, C. S., Netzer, H., Peterson, B. M., Bentz, M. C., Bisogni, S., Crenshaw, D. M., Denney, K. D., Ely, J., Fausnaugh, M. M., Grier, C. J., Gupta, A., Horne, K. D., Kaastra, J., Pancoast, A., Pei, L., Pogge, R. W., Skielboe, A., Starkey, D., Vestergaard, M., Zu, Y., Anderson, M. D., Arevalo, P., Bazhaw, C., Borman, G. A., Boroson, T. A., Bottorff, M. C., Brandt, W. N., Breeveld, A. A., Brewer, B. J., Cackett, E. M., Carini, M. T., Croxall, K. V., Bonta, E. Dalla, de Lorenzo-Caceres, A., Dietrich, M., Efimova, N. V., Evans, P. A., Filippenko, A. V., Flatland, K., Gehrels, N., Geier, S., Gelbord, G. M., Gonzalez, L., Gorjian, V., Grupe, D., Hall, P. B., Hicks, S., Horenstein, D., Hutchison, T., Im, M., Jensen, J. J., Joner, M. D., Jones, J., Kaspi, S., Kelly, B. C., Kennea, J. A., Kim, M., Kim, S. C., Klimanov, S. A., Larionov, V. M., Lee, J. C., Leonard, D. C., Lira, P., MacInnis, F., Manne-Nicholas, E. R., Mathur, S., McHardy, I. M., Montouri, C., Musso, R., Nazarov, S. V., Norris, R. P., Nousek, J. A., Okhmat, D. N., Papadakis, I., Parks, J. R., Pott, J. -U., Rafter, S. E., Rix, H. -W., Saylor, D. A., Schimoia, J. S., Schnulle, K., Sergeev, S. G., Siegel, M., Spencer, M., Sung, H. -I., Teems, K. G., Treu, T., Turner, C. S., Uttley, P., Villforth, C., Weiss, Y., Woo, J. -H., Yan, H., Young, S., and Zheng, W. -K.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

During an intensive Hubble Space Telescope (HST) Cosmic Origins Spectrograph (COS) UV monitoring campaign of the Seyfert~1 galaxy NGC 5548 performed from 2014 February to July, the normally highly correlated far-UV continuum and broad emission-line variations decorrelated for ~60 to 70 days, starting ~75 days after the first HST/COS observation. Following this anomalous state, the flux and variability of the broad emission lines returned to a more normal state. This transient behavior, characterised by significant deficits in flux and equivalent width of the strong broad UV emission lines, is the first of its kind to be unambiguously identified in an active galactic nucleus reverberation mapping campaign. The largest corresponding emission-line flux deficits occurred for the high-ionization collisionally excited lines, C IV and Si IV(+O IV]), and also He II(+O III]), while the anomaly in Ly-alpha was substantially smaller. This pattern of behavior indicates a depletion in the flux of photons with E_{\rm ph} > 54 eV, relative to those near 13.6 eV. We suggest two plausible mechanisms for the observed behavior: (i) temporary obscuration of the ionizing continuum incident upon BLR clouds by a moving veil of material lying between the inner accretion disk and inner BLR, perhaps resulting from an episodic ejection of material from the disk, or (ii) a temporary change in the intrinsic ionizing continuum spectral energy distribution resulting in a deficit of ionizing photons with energies > 54 eV, possibly due to a transient restructuring of the Comptonizing atmosphere above the disk. Current evidence appears to favor the latter explanation., Comment: 12 pages, 2 figures, accepted for publication in ApJ, Friday 25th March 2016. A movie of the anomalous emission-line behavior can be found in the ancilliary documents

Published
2016
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10. Multi-Wavelength Observations of the Blazar 1ES 1011+496 in Spring 2008

Author

The MAGIC Collaboration, Ahnen, M. L., Ansoldi, S., Antonelli, L. A., Antoranz, P., Babic, A., Banerjee, B., Bangale, P., de Almeida, U. Barres, Barrio, J. A., Gonzalez, J. Becerra, Bednarek, W., Bernardini, E., Biasuzzi, B., Biland, A., Blanch, O., Bonnefoy, S., Bonnoli, G., Borracci, F., Bretz, T., Carmona, E., Carosi, A., Chatterjee, A., Clavero, R., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., Da Vela, P., Dazzi, F., De Angelis, A., De Caneva, G., De Lotto, B., Wilhelmi, E. de Ona, Mendez, C. Delgado, Di Pierro, F., Prester, D. Dominis, Dorner, D., Doro, M., Einecke, S., Elsaesser, D., Fernandez-Barral, A., Fidalgo, D., Fonseca, M. V., Font, L., Frantzen, K., Fruck, C., Galindo, D., Lopez, R. J. Garcia, Garczarczyk, M., Terrats, D. Garrido, Gaug, M., Giammaria, P., Glawion, D., Godinovic, N., Munoz, A. Gonzalez, Guberman, D., Hanabata, Y., Hayashida, M., Herrera, J., Hose, J., Hrupec, D., Hughes, G., Idec, W., Kodani, K., Konno, Y., Kubo, H., Kushida, J., La Barbera, A., Lelas, D., Lindfors, E., Lombardi, S., Longo, F., Lopez, M., Lopez-Coto, R., Lopez-Oramas, A., Lorenz, E., Majumdar, P., Makariev, M., Mallot, K., Maneva, G., Manganaro, M., Mannheim, K., Maraschi, L., Marcote, B., Mariotti, M., Martinez, M., Mazin, D., Menzel, U., Miranda, J. M., Mirzoyan, R., Moralejo, A., Nakajima, D., Neustroev, V., Niedzwiecki, A., Rosillo, M. Nievas, Nilsson, K., Nishijima, K., Noda, K., Orito, R., Overkemping, A., Paiano, S., Palacio, J., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Paredes-Fortuny, X., Persic, M., Poutanen, J., Moroni, P. G. Prada, Prandini, E., Puljak, I., Reinthal, R., Rhode, W., Ribo, M., Rico, J., Garcia, J. Rodriguez, Rugamer, S., Saito, T., Satalecka, K., Scapin, V., Schultz, C., Schweizer, T., Shore, S. N., Sillanpaa, A., Sitarek, J., Snidaric, I., Sobczynska, D., Stamerra, A., Steinbring, T., Strzys, M., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzic, T., Tescaro, D., Teshima, M., Thaele, J., Torres, D. F., Toyama, T., Treves, A., Verguilov, V., Vovk, I., Ward, J. E., Will, M., Wu, M. H., Zanin, R., Lucarelli, F., Pittori, C., Vercellone, S., Berdyugin, A., Carini, M. T., Lahteenmaki, A., Pasanen, M., Pease, A., Sainio, J., Tornikoski, M., and Walters, R.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

The BL Lac object 1ES 1011+496 was discovered at Very High Energy gamma-rays by MAGIC in spring 2007. Before that the source was little studied in different wavelengths. Therefore a multi-wavelength (MWL) campaign was organized in spring 2008. Along MAGIC, the MWL campaign included the Metsahovi radio observatory, Bell and KVA optical telescopes and the Swift and AGILE satellites. MAGIC observations span from March to May, 2008 for a total of 27.9 hours, of which 19.4 hours remained after quality cuts. The light curve showed no significant variability. The differential VHE spectrum could be described with a power-law function. Both results were similar to those obtained during the discovery. Swift XRT observations revealed an X-ray flare, characterized by a harder when brighter trend, as is typical for high synchrotron peak BL Lac objects (HBL). Strong optical variability was found during the campaign, but no conclusion on the connection between the optical and VHE gamma-ray bands could be drawn. The contemporaneous SED shows a synchrotron dominated source, unlike concluded in previous work based on nonsimultaneous data, and is well described by a standard one zone synchrotron self Compton model. We also performed a study on the source classification. While the optical and X-ray data taken during our campaign show typical characteristics of an HBL, we suggest, based on archival data, that 1ES 1011+496 is actually a borderline case between intermediate and high synchrotron peak frequency BL Lac objects., Comment: 13 pages, accepted for publication in MNRAS

Published
2016
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11. Space Telescope and Optical Reverberation Mapping Project. III. Optical Continuum Emission and Broad-Band Time Delays in NGC 5548

Author

Fausnaugh, M. M., Denney, K. D., Barth, A. J., Bentz, M. C., Bottorff, M. C., Carini, M. T., Croxall, K. V., De Rosa, G., Goad, M. R., Horne, Keith, Joner, M. D., Kaspi, S., Kim, M., Klimanov, S. A., Kochanek, C. S., Leonard, D. C., Netzer, H., Peterson, B. M., Schnulle, K., Sergeev, S. G., Vestergaard, M., Zheng, W. -K., Zu, Y., Anderson, M. D., Arevalo, P., Bazhaw, C., Borman, G. A., Boroson, T. A., Brandt, W. N., Breeveld, A. A., Brewer, B. J., Cackett, E. M., Crenshaw, D. M., Bonta, E. Dalla, De Lorenzo-Caceres, A., Dietrich, M., Edelson, R., Efimova, N. V., Ely, J., Evans, P. A., Filippenko, A. V., Flatland, K., Gehrels, N., Geier, S., Gelbord, J. M., Gonzalez, L., Gorjian, V., Grier, C. J., Grupe, D., Hall, P. B., Hicks, S., Horenstein, D., Hutchison, T., Im, M., Jensen, J. J., Jones, J., Kaastra, J., Kelly, B. C., Kennea, J. A., Kim, S. C., Korista, K. T., Kriss, G. A., Lee, J. C., Lira, P., MacInnis, F., Manne-Nicholas, E. R., Mathur, S., McHardy, I. M., Montouri, C., Musso, R., Nazarov, S. V., Norris, R. P., Nousek, J. A., Okhmat, D. N., Pancoast, A., Papadakis, I., Parks, J. R., Pei, L., Pogge, R. W., Pott, J. -U., Rafter, S. E., Rix, H. -W., Saylor, D. A., Schimoia, J. S., Siegel, M., Spencer, M., Starkey, D., Sung, H. -I., Teems, K. G., Treu, T., Turner, C. S., Uttley, P., Villforth, C., Weiss, Y., Woo, J. -H., Yan, H., and Young, S.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

We present ground-based optical photometric monitoring data for NGC 5548, part of an extended multi-wavelength reverberation mapping campaign. The light curves have nearly daily cadence from 2014 January to July in nine filters (\emph{BVRI} and \emph{ugriz}). Combined with ultraviolet data from the \emph{Hubble Space Telescope} and \emph{Swift}, we confirm significant time delays between the continuum bands as a function of wavelength, extending the wavelength coverage from 1158\,\AA\ to the $z$ band ($\sim\!9160$\,\AA). We find that the lags at wavelengths longer than the {\it V} band are equal to or greater than the lags of high-ionization-state emission lines (such as He\,{\sc ii}\,$\lambda 1640$ and $\lambda 4686$), suggesting that the continuum-emitting source is of a physical size comparable to the inner broad-line region (BLR). The trend of lag with wavelength is broadly consistent with the prediction for continuum reprocessing by an accretion disk with $\tau \propto \lambda^{4/3}$. However, the lags also imply a disk radius that is 3 times larger than the prediction from standard thin-disk theory, assuming that the bolometric luminosity is 10\% of the Eddington luminosity ($L = 0.1L_{\rm Edd}$). Using optical spectra from the Large Binocular Telescope, we estimate the bias of the interband continuum lags due to BLR emission observed in the filters. We find that the bias for filters with high levels of BLR contamination ($\sim\! 20\%$) can be important for the shortest continuum lags, and likely has a significant impact on the {\it u} and {\it U} bands owing to Balmer continuum emission., Comment: 26 pages, 10 figures, accepted to ApJ. For a brief video describing the main results of this paper, please see: https://www.youtube.com/watch?v=yaYtcDvIoP0&feature=youtu.be

Published
2015
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12. Multiwavelength Observations of Markarian 421 in 2005 - 2006

Author

Horan, D., Acciari, V. A., Bradbury, S. M., Buckley, J. H., Bugaev, V., Byrum, K. L., Cannon, A., Celik, O., Cesarini, A., Chow, Y. C. K., Ciupik, L., Cogan, P., Falcone, A. D., Fegan, S. J., Finley, J. P., Fortin, P., Fortson, L. F., Gall, D., Gillanders, G. H., Grube, J., Gyuk, G., Hanna, D., Hays, E., Kertzman, M., Kildea, J., Konopelko, A., Krawczynski, H., Lang, M. J., Lee, K., Moriarty, P., Nagai, T., Niemiec, J., Ong, R. A., Perkins, J. S., Pohl, M., Quinn, J., Reynolds, P. T., Rose, H. J., Sembroski, G. H., Smith, A. W., Steele, D., Swordy, S. P., Toner, J. A., Vassiliev, V. V., Wakely, S. P., Weekes, T. C., White, R. J., Williams, D. A., Wood, M. D., Zitzer, B., Aller, H. D., Aller, M. F., Baker, M., Barnaby, D., Carini, M. T., Charlot, P., Dumm, J. P., Fields, N. E., Hovatta, T., Jordan, B., Kovalev, Y. A., Kovalev, Y. Y., Krimm, H. A., Kurtanidze, O. M., Lahteenmaki, A., Campion, J. F. Le, Maune, J., Montaruli, T., Sadun, A. C., Smith, S., Tornikoski, M., Turunen, M., and Walters, R.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Since September 2005, the Whipple 10m Gamma-ray Telescope has been operated primarily as a blazar monitor. The five Northern Hemisphere blazars that have already been detected at the Whipple Observatory, Markarian 421, H1426+428, Markarian 501, 1ES 1959+650 and 1ES 2344+514, are monitored routinely each night that they are visible. We report on the Markarian 421 observations taken from November 2005 to June 2006 in the gamma-ray, X-ray, optical and radio bands. During this time, Markarian 421 was found to be variable at all wavelengths probed. Both the variability and the correlations among different energy regimes are studied in detail here. A tentative correlation, with large spread, was measured between the X-ray and gamma-ray bands, while no clear correlation was evident among the other energy bands. In addition to this, the well-sampled spectral energy distribution of Markarian 421 (1101+384) is presented for three different activity levels. The observations of the other blazar targets will be reported separately., Comment: 58 pages, 22 Figures. Accepted for publication in ApJ

Published
2009
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13. Results from the Blazar Monitoring Campaign at the Whipple 10m Gamma-ray Telescope

Author

Steele, David, Carini, M. T., Charlot, P., Kurtanidze, O., Lahteenmaki, A., Montaruli, T., Sadun, A. C., and Villata, M.

Subjects
Astrophysics
Abstract

In September 2005, the observing program of the Whipple 10 m gamma-ray telescope was redefined to be dedicated almost exclusively to AGN monitoring. Since then the five Northern Hemisphere blazars that had already been detected at Whipple are monitored routinely each night that they are visible. Thanks to the efforts of a large number of multiwavelength collaborators, the first year of this program has been very successful. We report here on the analysis of Markarian 421 observations taken from November, 2005 to May, 2006 in the gamma-ray, X-ray, optical and radio bands., Comment: 4 pages; contribution to the 30th International Cosmic Ray Conference, Merida, Mexico, July 2007

Published
2007

14. Large-scale wind structures in OB supergiants: a search for rotationally modulated H\alpha variability

Author

Morel, T., Marchenko, S. V., Pati, A. K., Kuppuswamy, K., Carini, M. T., Wood, E., and Zimmerman, R.

Subjects
Astrophysics
Abstract

We present the results of a long-term monitoring campaign of the H\alpha line in a sample of bright OB-supergiants (O7.5-B9) that aims at detecting rotationally modulated changes potentially related to the existence of large-scale wind structures. A total of 22 objects were monitor ed during 36 nights spread over 6 months in 2001-2002. Coordinated broad-band photometric observations were also obtained for some targets. Conspicuous evidence for variability in H\alpha is found for the stars displaying a feature contaminated by wind emission. Most changes take place on a daily time-scale, although hourly variations are also occasionally detected. Convincing evidence for a cyclical pattern of variability in H\alpha has been found in 2 stars: HD 14134 and HD 42087 (periodic signals are also detected in other stars, but independent confirmation is required). Rotational modulation is suggested from the similarity between the observed recurrence time-scales (in the range 13-25 days) and estimated periods of stellar rotation. We call attention to the atypical case of HD 14134 which exhibits a clear 12.8-d periodicity both in the photometric and in the spectroscopic data sets. This places this object among a handful of early-type stars where one may observe a clear link between extended wind structures and photospheric disturbances. Further modelling may test the hypothesis that azimuthally-extended wind streams are responsible for the patterns of spectral variability in our target stars., Comment: 18 pages, accepted for publication in MNRAS

Published
2004
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15. Day-Scale Variability of 3C 279 and Searches for Correlations in Gamma-Ray, X-Ray, and Optical Bands

Author

Hartman, R. C., Villata, M., Balonek, T. J., Bertsch, D. L., Bock, H., Boettcher, M., Carini, M. T., Collmar, W., De Francesco, G., Ferrara, E. C., Heidt, J., Kanbach, G., Katajainen, S., Koskimies, M., Kurtanidze, O. M., Lanteri, L., Lawson, A., Lin, Y. C., Marscher, A. P., McFarland, J. P., McHardy, I. M., Miller, H. R., Nikolashvili, M., Nilsson, K., Noble, J. C., Nucciarelli, G., Ostorero, L., Pursimo, T., Raiteri, C. M., Rekola, R., Savolainen, T., Sillanpaa, A., Smale, A., Sobrito, G., Takalo, L. O., Thompson, D. J., Tosti, G., Wagner, S. J., and Wilson, J. W.

Subjects
Astrophysics
Abstract

Light curves of 3C 279 are presented in optical (R-band), X-rays (RXTE/PCA), and gamma rays (CGRO/EGRET) for 1999 Jan-Feb and 2000 Jan-Mar. During both of those epochs the gamma-ray levels were high, and all three observed bands demonstrated substantial variation, on time scales as short as one day. Correlation analyses provided no consistent pattern, although a rather significant optical/gamma-ray correlation was seen in 1999, with a gamma-ray lag of ~2.5 days, and there are other suggestions of correlations in the light curves. For comparison, correlation analysis is also presented for the gamma-ray and X-ray light curves during the large gamma ray flare in 1996 Feb and the two gamma-bright weeks leading up to it; the correlation at that time was strong, with a gamma-ray/X-ray offset of no more than 1 day., Comment: 20 pages, including 7 figures; accepted by The Astrophysical Journal

Published
2001
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16. The Great Markarian 421 Flare of 2010 February: Multiwavelength Variability and Correlation Studies

Author

Abeysekara, A. U., Benbow, W., Bird, R., Brill, A., Brose, R., Buchovecky, M., Buckley, J. H., Christiansen, J. L., Chromey, A. J., Daniel, M. K., Dumm, J., Falcone, A., Feng, Q., Finley, J. P., Fortson, L., Furniss, A., Galante, N., Gent, A., Gillanders, G. H., Giuri, C., Gueta, O., Hassan, T., Hervet, O., Holder, J., Hughes, G., Humensky, T. B., Johnson, C. A., Kaaret, P., Kar, P., Kelley-Hoskins, N., Kertzman, M., Kieda, D., Krause, M., Krennrich, F., Kumar, S., Lang, M. J., Moriarty, P., Mukherjee, R., Nelson, T., Nieto, D., Nievas-Rosillo, M., O’Brien, S., Ong, R. A., Otte, A. N., Park, N., Petrashyk, A., Pichel, A., Pohl, M., Prado, R. R., Pueschel, E., Quinn, J., Ragan, K., Reynolds, P. T., Richards, G. T., Roache, E., Rovero, A. C., Rulten, C., Sadeh, I., Santander, M., Sembroski, G. H., Shahinyan, K., Stevenson, B., Sushch, I., Tyler, J., Vassiliev, V. V., Wakely, S. P., Weinstein, A., Wells, R. M., Wilcox, P., Wilhelm, A., Williams, D. A., Zitzer, B., Acciari, V. A., Ansoldi, S., Antonelli, L. A., Arbet Engels, A., Baack, D., Babić, A., Banerjee, B., Barres de Almeida, U., Barrio, J. A., Becerra González, J., Bednarek, W., Bellizzi, L., Bernardini, E., Berti, A., Besenrieder, J., Bhattacharyya, W., Bigongiari, C., Biland, A., Blanch, O., Bonnoli, G., Busetto, G., Carosi, R., Ceribella, G., Chai, Y., Cikota, S., Colak, S. M., Colin, U., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., D’Elia, V., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., Delfino, M., Delgado, J., Di Pierro, F., Do Souto Espiñera, E., Dominis Prester, D., Dorner, D., Doro, M., Einecke, S., Elsaesser, D., Fallah Ramazani, V., Fattorini, A., Fernández-Barral, A., Ferrara, G., Fidalgo, D., Foffano, L., Fonseca, M. V., Font, L., Fruck, C., Galindo, D., Gallozzi, S., García López, R. J., Garczarczyk, M., Gasparyan, S., Gaug, M., Godinović, N., Green, D., Guberman, D., Hadasch, D., Hahn, A., Herrera, J., Hoang, J., Hrupec, D., Inoue, S., Ishio, K., Iwamura, Y., Kubo, H., Kushida, J., Lamastra, A., Lelas, D., Leone, F., Lindfors, E., Lombardi, S., Longo, F., López, M., López-Coto, R., López-Oramas, A., Machado de Oliveira Fraga, B., Maggio, C., Majumdar, P., Makariev, M., Mallamaci, M., Maneva, G., Manganaro, M., Mannheim, K., Maraschi, L., Mariotti, M., Martínez, M., Masuda, S., Mazin, D., Miceli, D., Minev, M., Miranda, J. M., Mirzoyan, R., Molina, E., Moralejo, A., Morcuende, D., Moreno, V., Moretti, E., Munar-Adrover, P., Neustroev, V., Niedzwiecki, A., Nievas Rosillo, M., Nigro, C., Nilsson, K., Ninci, D., Nishijima, K., Noda, K., Nogués, L., Nöthe, M., Paiano, S., Palacio, J., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Peñil, P., Peresano, M., Persic, M., Prada Moroni, P. G., Prandini, E., Puljak, I., Rhode, W., Ribó, M., Rico, J., Righi, C., Rugliancich, A., Saha, L., Sahakyan, N., Saito, T., Satalecka, K., Schweizer, T., Sitarek, J., Šnidarić, I., Sobczynska, D., Somero, A., Stamerra, A., Strom, D., Strzys, M., Sun, S., Surić, T., Tavecchio, F., Temnikov, P., Terzić, T., Teshima, M., Torres-Albà, N., Tsujimoto, S., van Scherpenberg, J., Vanzo, G., Vazquez Acosta, M., Vovk, I., Will, M., Zarić, D., Aller, H. D., Aller, M. F., Carini, M. T., Horan, D., Jordan, B., Jorstad, S. G., Kurtanidze, O. M., Kurtanidze, S. O., Lähteenmäki, A., Larionov, V. M., Larionova, E. G., Madejski, G., Marscher, A. P., Max-Moerbeck, W., Moody, J. Ward, Morozova, D. A., Nikolashvili, M. G., Raiteri, C. M., Readhead, A. C. S., Richards, J. L., Sadun, A. C., Sakamoto, T., Sigua, L. A., Smith, P. S., Talvikki, H., Tammi, J., Tornikoski, M., Troitsky, I. S., Villata, M., (VERITAS Collaboration), (MAGIC Collaboration), (Multiwavelength Partners), Department of Energy (US), Smithsonian Institution, National Science Foundation (US), National Energy Research Scientific Computing Center (US), German Research Foundation, Istituto Nazionale di Fisica Nucleare, Istituto Nazionale di Astrofisica, Ministerio de Economía y Competitividad (España), Department of Atomic Energy (India), Japan Society for the Promotion of Science, Ministry of Education, Culture, Sports, Science and Technology (Japan), Croatian Science Foundation, University of Rijeka, Polish National Agency for Academic Exchange, National Aeronautics and Space Administration (US), Shota Rustaveli National Science Foundation, Boston University, University of Utah, Harvard University, University of California Los Angeles, Columbia University, University of Potsdam, Washington University St. Louis, California Polytechnic State University, San Luis Obispo, Iowa State University, University of Minnesota Twin Cities, Pennsylvania State University, Purdue University, California State University, East Bay, Georgia Institute of Technology, National University of Ireland, Galway, German Electron Synchrotron, University of California Santa Cruz, University of Delaware, University of Iowa, DePauw University, McGill University, Complutense University, University College Dublin, University of Wisconsin-Madison, Universidad de Buenos Aires, Cork Institute of Technology, University of Alabama, University of Chicago, Instituto de Astrofísica de Canarias, University of Udine, INAF, Osservatorio Astronomico di Roma, Swiss Federal Institute of Technology Zurich, Dortmund University, Saha Institute of Nuclear Physics, Centro Brasileiro de Pesquisas Físicas, University of Łódź, University of Siena, National Institute for Nuclear Physics, Max Planck Institute for Physics, Institute for High Energy Physics, University of Padova, University of Pisa, University of Würzburg, University of Turku, Autonomous University of Barcelona, University of Barcelona, National Academy of Sciences of the Republic of Armenia, The University of Tokyo, Bulgarian Academy of Sciences, Fudan University, University of Michigan, Ann Arbor, Western Kentucky University, CNRS, Dublin Institute for Advanced Studies, Ilia State University, Department of Electronics and Nanoengineering, St. Petersburg State University, United States Department of Energy, Universidad de Chile, Brigham Young University, California Institute of Technology, University of Colorado Denver, Aoyama Gakuin University, University of Arizona, Metsähovi Radio Observatory, Aalto-yliopisto, Aalto University, Abeysekara, A. U., Benbow, W., Bird, R., Brill, A., Brose, R., Buchovecky, M., Buckley, J. H., Christiansen, J. L., Chromey, A. J., Daniel, M. K., Dumm, J., Falcone, A., Feng, Q., Finley, J. P., Fortson, L., Furniss, A., Galante, N., Gent, A., Gillanders, G. H., Giuri, C., Gueta, O., Hassan, T., Hervet, O., Holder, J., Hughes, G., Humensky, T. B., Johnson, C. A., Kaaret, P., Kar, P., Kelley-Hoskins, N., Kertzman, M., Kieda, D., Krause, M., Krennrich, F., Kumar, S., Lang, M. J., Moriarty, P., Mukherjee, R., Nelson, T., Nieto, D., Nievas-Rosillo, M., O'Brien, S., Ong, R. A., Otte, A. N., Park, N., Petrashyk, A., Pichel, A., Pohl, M., Prado, R. R., Pueschel, E., Quinn, J., Ragan, K., Reynolds, P. T., Richards, G. T., Roache, E., Rovero, A. C., Rulten, C., Sadeh, I., Santander, M., Sembroski, G. H., Shahinyan, K., Stevenson, B., Sushch, I., Tyler, J., Vassiliev, V. V., Wakely, S. P., Weinstein, A., Wells, R. M., Wilcox, P., Wilhelm, A., Williams, D. A., Zitzer, B., Acciari, V. A., Ansoldi, S., Antonelli, L. A., Arbet Engels, A., Baack, D., Babic, A., Banerjee, B., Barres De Almeida, U., Barrio, J. A., Becerra Gonzalez, J., Bednarek, W., Bellizzi, L., Bernardini, E., Berti, A., Besenrieder, J., Bhattacharyya, W., Bigongiari, C., Biland, A., Blanch, O., Bonnoli, G., Busetto, G., Carosi, R., Ceribella, G., Chai, Y., Cikota, S., Colak, S. M., Colin, U., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., D'Elia, V., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., Delfino, M., Delgado, J., Di Pierro, F., Do Souto Espiñera, E., Dominis Prester, D., Dorner, D., Doro, M., Einecke, S., Elsaesser, D., Fallah Ramazani, V., Fattorini, A., Fernandez-Barral, A., Ferrara, G., Fidalgo, D., Foffano, L., Fonseca, M. V., Font, L., Fruck, C., Galindo, D., Gallozzi, S., Garcia Lopez, R. J., Garczarczyk, M., Gasparyan, S., Gaug, M., Godinovic, N., Green, D., Guberman, D., Hadasch, D., Hahn, A., Herrera, J., Hoang, J., Hrupec, D., Inoue, S., Ishio, K., Iwamura, Y., Kubo, H., Kushida, J., Lamastra, A., Lelas, D., Leone, F., Lindfors, E., Lombardi, S., Longo, F., Lopez, M., Lopez-Coto, R., Lopez-Oramas, A., Machado De Oliveira Fraga, B., Maggio, C., Majumdar, P., Makariev, M., Mallamaci, M., Maneva, G., Manganaro, M., Mannheim, K., Maraschi, L., Mariotti, M., Martinez, M., Masuda, S., Mazin, D., Miceli, D., Minev, M., Miranda, J. M., Mirzoyan, R., Molina, E., Moralejo, A., Morcuende, D., Moreno, V., Moretti, E., Munar-Adrover, P., Neustroev, V., Niedzwiecki, A., Nievas Rosillo, M., Nigro, C., Nilsson, K., Ninci, D., Nishijima, K., Noda, K., Nogues, L., Nothe, M., Paiano, S., Palacio, J., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Peñil, P., Peresano, M., Persic, M., Prada Moroni, P. G., Prandini, E., Puljak, I., Rhode, W., Ribo, M., Rico, J., Righi, C., Rugliancich, A., Saha, L., Sahakyan, N., Saito, T., Satalecka, K., Schweizer, T., Sitarek, J., Snidaric, I., Sobczynska, D., Somero, A., Stamerra, A., Strom, D., Strzys, M., Sun, S., Suric, T., Tavecchio, F., Temnikov, P., Terzic, T., Teshima, M., Torres-Alba, N., Tsujimoto, S., Van Scherpenberg, J., Vanzo, G., Vazquez Acosta, M., Vovk, I., Will, M., Zaric, D., Aller, H. D., Aller, M. F., Carini, M. T., Horan, D., Jordan, B., Jorstad, S. G., Kurtanidze, O. M., Kurtanidze, S. O., Lahteenmaki, A., Larionov, V. M., Larionova, E. G., Madejski, G., Marscher, A. P., Max-Moerbeck, W., Moody, J. W., Morozova, D. A., Nikolashvili, M. G., Raiteri, C. M., Readhead, A. C. S., Richards, J. L., Sadun, A. C., Sakamoto, T., Sigua, L. A., Smith, P. S., Talvikki, H., Tammi, J., Tornikoski, M., Troitsky, I. S., and Villata, M.

Subjects
Multiple days, Gamma-ray astronomY, 010504 meteorology & atmospheric sciences, Astrophysics::High Energy Astrophysical Phenomena, Flux, Markarian galaxies, Astrophysics, Blazar, 01 natural sciences, 7. Clean energy, BL Lacertae object, High energy astrophysic, law.invention, law, Observatory, BL Lacertae objects, Blazars, High energy astrophysics, Relativistic jets, Gamma-ray astronomy, Time domain astronomy, Relativistic jet, 0103 physical sciences, MAGIC (telescope), BL lacertae objects, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Physics, Astronomy and Astrophysics, Light curve, Space and Planetary Science, Markarian galaxie, Electrónica, Electricidad, Flare
Abstract

We report on variability and correlation studies using multiwavelength observations of the blazar Mrk 421 during the month of 2010 February, when an extraordinary flare reaching a level of ∼27 Crab Units above 1 TeV was measured in very high energy (VHE) γ-rays with the Very Energetic Radiation Imaging Telescope Array System (VERITAS) observatory. This is the highest flux state for Mrk 421 ever observed in VHE γ-rays. Data are analyzed from a coordinated campaign across multiple instruments, including VHE γ-ray (VERITAS, Major Atmospheric Gamma-ray Imaging Cherenkov), high-energy γ-ray (Fermi-LAT), X-ray (Swift, Rossi X-ray Timing Experiment, MAXI), optical (including the GASP-WEBT collaboration and polarization data), and radio (Metsahovi, Owens Valley Radio Observatory, University of Michigan Radio Astronomy Observatory). Light curves are produced spanning multiple days before and after the peak of the VHE flare, including over several flare "decline" epochs. The main flare statistics allow 2 minute time bins to be constructed in both the VHE and optical bands enabling a cross-correlation analysis that shows evidence for an optical lag of ∼25-55 minutes, the first time-lagged correlation between these bands reported on such short timescales. Limits on the Doppler factor (δ ⪆ 33) and the size of the emission region (δR≲ 3.8 × 10cm) are obtained from the fast variability observed by VERITAS during the main flare. Analysis of 10 minute binned VHE and X-ray data over the decline epochs shows an extraordinary range of behavior in the flux-flux relationship, from linear to quadratic to lack of correlation to anticorrelation. Taken together, these detailed observations of an unprecedented flare seen in Mrk 421 are difficult to explain with the classic single-zone synchrotron self-Compton model., This research is supported by grants from the U.S. Department of Energy Office of Science, the U.S. National Science Foundation, the Smithsonian Institution, and NSERC in Canada. This research used resources provided by the Open Science Grid, which is supported by the National Science Foundation and the U.S. Department of Energy’s Office of Science, and the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility operated under contract No. DE-AC02- 05CH11231. We acknowledge the excellent work of the technical support staff at the Fred Lawrence Whipple Observatory and the collaborating institutions in the construction and operation of the instrument. The MAGIC collaboration would like to thank the Instituto de Astrofísica de Canarias for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma. The financial support of the German BMBF and MPG, the Italian INFN and INAF, the Swiss National Fund SNF, the ERDF under the Spanish MINECO (FPA2015-69818-P, FPA2012-36668, FPA2015-68378-P, FPA2015-69210-C6-2- R, FPA2015-69210-C6-4-R, FPA2015-69210-C6-6-R, AYA2015-71042-P, AYA2016-76012-C3-1-P, ESP2015- 71662-C2-2-P, FPA201790566REDC), the Indian Department of Atomic Energy, the Japanese JSPS and MEXT, and the Bulgarian Ministry of Education and Science, National RI Roadmap Project DO1-153/28.08.2018 is gratefully acknowledged. This work was also supported by the Spanish Centro de Excelencia “Severo Ochoa” SEV-2016-0588 and SEV2015-0548 and Unidad de Excelencia “María de Maeztu” MDM-2014-0369, the Croatian Science Foundation (HrZZ) Project IP-2016-06-9782, the University of Rijeka Project 13.12.1.3.02, the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3, the Polish National Research Centre grant UMO-2016/22/M/ST9/00382, and the Brazilian MCTIC, CNPq, and FAPERJ. This publication makes use of data obtained at Metsähovi Radio Observatory, operated by Aalto University, Finland, and the OVRO 40 m monitoring program, which is supported in part by NASA grants NNX08AW31G, NNX11A043G, and NNX14AQ89G and NSF grants AST-0808050 and AST1109911. The UMRAO data were obtained through NSF grant AST 0607523 and NASA Fermi GI award NNX09AU16G. The St. Petersburg University team acknowledges support from Russian RFBR foundation, grant 12-02-00452. The Abastumani Observatory team acknowledges financial support by the Shota Rustaveli National Science Foundation through project FR/577/6-320/13. The Steward Observatory data were obtained under Fermi Guest Investigator Program grant NNX09AU10G. The research at Boston University is supported by NASA grant 80NSSC17K0649 and NSF grant AST-1615796. Software. VEGAS (Cogan 2008), Event Display (Daniel 2008), MARS (Moralejo et al. 2009), Fermi Science Tools81, HEASoft (FTOOLS+XANADU; HEASARC 2014), REX,85 Xspec (Arnaud 1996), emcee (Foreman-Mackey et al. 2013).

Published
2020

17. Space Telescope and Optical Reverberation Mapping Project. IX. Velocity-Delay Maps for Broad Emission Lines in NGC 5548

Author

Horne, Keith, Rosa, G. De, Peterson, B. M., Barth, A. J., Ely, J., Fausnaugh, M. M., Kriss, G. A., Pei, L., Bentz, M. C., Cackett, E. M., Edelson, R., Eracleous, M., Goad, M. R., Grier, C. J., Kaastra, J., Kochanek, C. S., Krongold, Y., Mathur, S., Netzer, H., Proga, D., Tejos, N., Vestergaard, M., Villforth, C., Adams, S. M., Anderson, M. D., Arevalo, P., Beatty, T. G., Bennert, V. N., Bigley, A., Bisogni, S., Borman, G. A., Boroson, T. A., Bottorff, M. C., Brandt, W. N., Breeveld, A. A., Brotherton, M., Brown, J. E., Brown, J. S., Canalizo, G., Carini, M. T., Clubb, K. I., Comerford, J. M., Corsini, E. M., Crenshaw, D. M., Croft, S., Croxall, K. V., Bonta, E. Dalla, Deason, A. J., Dehghanian, M., Lorenzo-Caceres, A. De, Denney, K. D., Dietrich, M., Done, C., Efimova, N. V., Evans, P. A., Ferland, G. J., Filippenko, A. V., Flatland, K., Fox, O. D., Gardner, E., Gates, E. L., Gehrels, N., Geier, S., Gelbord, J. M., Gonzalez, L., Gorjian, V., Greene, J. E., Grupe, D., Gupta, A., Hall, P. B., Henderson, C. B., Hicks, S., Holmbeck, E., Holoien, T. W. -S., Hutchison, T., Im, M., Jensen, J. J., Johnson, C. A., Joner, M. D., Jones, J., Kaspi, S., Kelly, P. L., Kennea, J. A., Kim, M., Kim, S., Kim, S. C., King, A., Klimanov, S. A., Korista, K. T., Lau, M. W., Lee, J. C., Leonard, D. C., Li, Miao, Lira, P., Lochhaas, C., Ma, Zhiyuan, MacInnis, F., Malkan, M. A., Manne-Nicholas, E. R., Mauerhan, J. C., McGurk, R., McHardy, I. M., Montuori, C., Morelli, L., Mosquera, A., Mudd, D., Muller-Sanchez, F., Nazarov, S. V., Norris, R. P., Nousek, J. A., Nguyen, M. L., Ochner, P., Okhmat, D. N., Pancoast, A., Papadakis, I., Parks, J. R., Penny, M. T., Pizzella, A., Pogge, R. W., Poleski, R., Pott, J. -U., Rafter, S. E., Rix, H. -W., Runnoe, J., Saylor, D. A., Schimoia, J. S., Schnuelle, K., Scott, B., Sergeev, S. G., Shappee, B. J., Shivvers, I., Siegel, M., Simonian, G. V., Siviero, A., Skielboe, A., Somers, G., Spencer, M., Starkey, D., Stevens, D. J., Sung, H. -I., Tayar, J., Treu, T., Turner, C. S., Uttley, P., Van Saders, J., Vican, L., Villanueva, S., Weiss, Y., Woo, J. -H., Yan, H., Young, S., Yuk, H., Zheng, W., Zhu, W., Zu, Y., Horne, Keith, Rosa, G. De, Peterson, B. M., Barth, A. J., Ely, J., Fausnaugh, M. M., Kriss, G. A., Pei, L., Bentz, M. C., Cackett, E. M., Edelson, R., Eracleous, M., Goad, M. R., Grier, C. J., Kaastra, J., Kochanek, C. S., Krongold, Y., Mathur, S., Netzer, H., Proga, D., Tejos, N., Vestergaard, M., Villforth, C., Adams, S. M., Anderson, M. D., Arevalo, P., Beatty, T. G., Bennert, V. N., Bigley, A., Bisogni, S., Borman, G. A., Boroson, T. A., Bottorff, M. C., Brandt, W. N., Breeveld, A. A., Brotherton, M., Brown, J. E., Brown, J. S., Canalizo, G., Carini, M. T., Clubb, K. I., Comerford, J. M., Corsini, E. M., Crenshaw, D. M., Croft, S., Croxall, K. V., Bonta, E. Dalla, Deason, A. J., Dehghanian, M., Lorenzo-Caceres, A. De, Denney, K. D., Dietrich, M., Done, C., Efimova, N. V., Evans, P. A., Ferland, G. J., Filippenko, A. V., Flatland, K., Fox, O. D., Gardner, E., Gates, E. L., Gehrels, N., Geier, S., Gelbord, J. M., Gonzalez, L., Gorjian, V., Greene, J. E., Grupe, D., Gupta, A., Hall, P. B., Henderson, C. B., Hicks, S., Holmbeck, E., Holoien, T. W. -S., Hutchison, T., Im, M., Jensen, J. J., Johnson, C. A., Joner, M. D., Jones, J., Kaspi, S., Kelly, P. L., Kennea, J. A., Kim, M., Kim, S., Kim, S. C., King, A., Klimanov, S. A., Korista, K. T., Lau, M. W., Lee, J. C., Leonard, D. C., Li, Miao, Lira, P., Lochhaas, C., Ma, Zhiyuan, MacInnis, F., Malkan, M. A., Manne-Nicholas, E. R., Mauerhan, J. C., McGurk, R., McHardy, I. M., Montuori, C., Morelli, L., Mosquera, A., Mudd, D., Muller-Sanchez, F., Nazarov, S. V., Norris, R. P., Nousek, J. A., Nguyen, M. L., Ochner, P., Okhmat, D. N., Pancoast, A., Papadakis, I., Parks, J. R., Penny, M. T., Pizzella, A., Pogge, R. W., Poleski, R., Pott, J. -U., Rafter, S. E., Rix, H. -W., Runnoe, J., Saylor, D. A., Schimoia, J. S., Schnuelle, K., Scott, B., Sergeev, S. G., Shappee, B. J., Shivvers, I., Siegel, M., Simonian, G. V., Siviero, A., Skielboe, A., Somers, G., Spencer, M., Starkey, D., Stevens, D. J., Sung, H. -I., Tayar, J., Treu, T., Turner, C. S., Uttley, P., Van Saders, J., Vican, L., Villanueva, S., Weiss, Y., Woo, J. -H., Yan, H., Young, S., Yuk, H., Zheng, W., Zhu, W., and Zu, Y.

Abstract

In this contribution, we achieve the primary goal of the active galactic nucleus (AGN) STORM campaign by recovering velocity-delay maps for the prominent broad emission lines (Ly alpha, C IV, He II, and H beta) in the spectrum of NGC 5548. These are the most detailed velocity-delay maps ever obtained for an AGN, providing unprecedented information on the geometry, ionization structure, and kinematics of the broad-line region. Virial envelopes enclosing the emission-line responses show that the reverberating gas is bound to the black hole. A stratified ionization structure is evident. The He ii response inside 5-10 lt-day has a broad single-peaked velocity profile. The Ly alpha, C IV, and H beta responses extend from inside 2 to outside 20 lt-day, with double peaks at 2500 km s(-1) in the 10-20 lt-day delay range. An incomplete ellipse in the velocity-delay plane is evident in H beta. We interpret the maps in terms of a Keplerian disk with a well-defined outer rim at R = 20 lt-day. The far-side response is weaker than that from the near side. The line-center delay tau = (R/c)(1 - sin i) approximate to 5 days gives the inclination i approximate to 45 degrees. The inferred black hole mass is (BH) 7 x 10(7) M-circle dot. In addition to reverberations, the fit residuals confirm that emission-line fluxes are depressed during the "BLR Holiday" identified in previous work. Moreover, a helical "Barber-Pole" pattern, with stripes moving from red to blue across the C IV and Ly alpha line profiles, suggests azimuthal structure rotating with a 2 yr period that may represent precession or orbital motion of inner-disk structures casting shadows on the emission-line region farther out.

Published
2021

18. Space Telescope and Optical Reverberation Mapping Project. IX. Velocity–Delay Maps for Broad Emission Lines in NGC 5548

Author

Horne, Keith, primary, Rosa, G. De, additional, Peterson, B. M., additional, Barth, A. J., additional, Ely, J., additional, Fausnaugh, M. M., additional, Kriss, G. A., additional, Pei, L., additional, Bentz, M. C., additional, Cackett, E. M., additional, Edelson, R., additional, Eracleous, M., additional, Goad, M. R., additional, Grier, C. J., additional, Kaastra, J., additional, Kochanek, C. S., additional, Krongold, Y., additional, Mathur, S., additional, Netzer, H., additional, Proga, D., additional, Tejos, N., additional, Vestergaard, M., additional, Villforth, C., additional, Adams, S. M., additional, Anderson, M. D., additional, Arévalo, P., additional, Beatty, T G., additional, Bennert, V. N., additional, Bigley, A., additional, Bisogni, S., additional, Borman, G. A., additional, Boroson, T. A., additional, Bottorff, M. C., additional, Brandt, W. N., additional, Breeveld, A. A., additional, Brotherton, M., additional, Brown, J. E., additional, Brown, J. S., additional, Canalizo, G., additional, Carini, M. T., additional, Clubb, K. I., additional, Comerford, J. M., additional, Corsini, E. M., additional, Crenshaw, D. M., additional, Croft, S., additional, Croxall, K. V., additional, Bontà, E. Dalla, additional, Deason, A. J., additional, Dehghanian, M., additional, Lorenzo-Cáceres, A. De, additional, Denney, K. D., additional, Dietrich, M., additional, Done, C., additional, Efimova, N. V., additional, Evans, P. A., additional, Ferland, G. J., additional, Filippenko, A. V., additional, Flatland, K., additional, Fox, O. D., additional, Gardner, E., additional, Gates, E. L., additional, Gehrels, N., additional, Geier, S., additional, Gelbord, J. M., additional, Gonzalez, L., additional, Gorjian, V., additional, Greene, J. E., additional, Grupe, D., additional, Gupta, A., additional, Hall, P. B., additional, Henderson, C. B., additional, Hicks, S., additional, Holmbeck, E., additional, Holoien, T. W.-S., additional, Hutchison, T., additional, Im, M., additional, Jensen, J. J., additional, Johnson, C. A., additional, Joner, M. D., additional, Jones, J., additional, Kaspi, S., additional, Kelly, P. L., additional, Kennea, J. A., additional, Kim, M., additional, Kim, S., additional, Kim, S. C., additional, King, A., additional, Klimanov, S. A., additional, Korista, K. T., additional, Lau, M. W., additional, Lee, J. C., additional, Leonard, D. C., additional, Li, Miao, additional, Lira, P., additional, Lochhaas, C., additional, Ma, Zhiyuan, additional, MacInnis, F., additional, Malkan, M. A., additional, Manne-Nicholas, E. R., additional, Mauerhan, J. C., additional, McGurk, R., additional, McHardy, I. M., additional, Montuori, C., additional, Morelli, L., additional, Mosquera, A., additional, Mudd, D., additional, Müller–Sánchez, F., additional, Nazarov, S. V., additional, Norris, R. P., additional, Nousek, J. A., additional, Nguyen, M. L., additional, Ochner, P., additional, Okhmat, D. N., additional, Pancoast, A., additional, Papadakis, I., additional, Parks, J. R., additional, Penny, M. T., additional, Pizzella, A., additional, Pogge, R. W., additional, Poleski, R., additional, Pott, J.-U., additional, Rafter, S. E., additional, Rix, H.-W., additional, Runnoe, J., additional, Saylor, D. A., additional, Schimoia, J. S., additional, Schnülle, K., additional, Scott, B., additional, Sergeev, S. G., additional, Shappee, B. J., additional, Shivvers, I., additional, Siegel, M., additional, Simonian, G. V., additional, Siviero, A., additional, Skielboe, A., additional, Somers, G., additional, Spencer, M., additional, Starkey, D., additional, Stevens, D. J., additional, Sung, H.-I., additional, Tayar, J., additional, Treu, T., additional, Turner, C. S., additional, Uttley, P., additional, Van Saders, J., additional, Vican, L., additional, Villanueva, S., additional, Weiss, Y., additional, Woo, J.-H., additional, Yan, H., additional, Young, S., additional, Yuk, H., additional, Zheng, W., additional, Zhu, W., additional, and Zu, Y., additional

Published
2021
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19. Space Telescope and Optical Reverberation Mapping Project. XII. Broad-line Region Modeling of NGC 5548

Author

Williams, P. R., primary, Pancoast, A., additional, Treu, T., additional, Brewer, B. J., additional, Peterson, B. M., additional, Barth, A. J., additional, Malkan, M. A., additional, Rosa, G. De, additional, Horne, Keith, additional, Kriss, G. A., additional, Arav, N., additional, Bentz, M. C., additional, Cackett, E. M., additional, Bontà, E. Dalla, additional, Dehghanian, M., additional, Done, C., additional, Ferland, G. J., additional, Grier, C. J., additional, Kaastra, J., additional, Kara, E., additional, Kochanek, C. S., additional, Mathur, S., additional, Mehdipour, M., additional, Pogge, R. W., additional, Proga, D., additional, Vestergaard, M., additional, Waters, T., additional, Adams, S. M., additional, Anderson, M. D., additional, Arévalo, P., additional, Beatty, T. G., additional, Bennert, V. N., additional, Bigley, A., additional, Bisogni, S., additional, Borman, G. A., additional, Boroson, T. A., additional, Bottorff, M. C., additional, Brandt, W. N., additional, Breeveld, A. A., additional, Brotherton, M., additional, Brown, J. E., additional, Brown, J. S., additional, Canalizo, G., additional, Carini, M. T., additional, Clubb, K. I., additional, Comerford, J. M., additional, Corsini, E. M., additional, Crenshaw, D. M., additional, Croft, S., additional, Croxall, K. V., additional, Deason, A. J., additional, Lorenzo-Cáceres, A. De, additional, Denney, K. D., additional, Dietrich, M., additional, Edelson, R., additional, Efimova, N. V., additional, Ely, J., additional, Evans, P. A., additional, Fausnaugh, M. M., additional, Filippenko, A. V., additional, Flatland, K., additional, Fox, O. D., additional, Gardner, E., additional, Gates, E. L., additional, Gehrels, N., additional, Geier, S., additional, Gelbord, J. M., additional, Gonzalez, L., additional, Gorjian, V., additional, Greene, J. E., additional, Grupe, D., additional, Gupta, A., additional, Hall, P. B., additional, Henderson, C. B., additional, Hicks, S., additional, Holmbeck, E., additional, Holoien, T. W.-S., additional, Hutchison, T., additional, Im, M., additional, Jensen, J. J., additional, Johnson, C. A., additional, Joner, M. D., additional, Jones, J., additional, Kaspi, S., additional, Kelly, P. L., additional, Kennea, J. A., additional, Kim, M., additional, Kim, S., additional, Kim, S. C., additional, King, A., additional, Klimanov, S. A., additional, Knigge, C., additional, Krongold, Y., additional, Lau, M. W., additional, Lee, J. C., additional, Leonard, D. C., additional, Li, Miao, additional, Lira, P., additional, Lochhaas, C., additional, Ma, Zhiyuan, additional, MacInnis, F., additional, Manne-Nicholas, E. R., additional, Mauerhan, J. C., additional, McGurk, R., additional, McHardy, I. M., additional, Montuori, C., additional, Morelli, L., additional, Mosquera, A., additional, Mudd, D., additional, Müller–Sánchez, F., additional, Nazarov, S. V., additional, Norris, R. P., additional, Nousek, J. A., additional, Nguyen, M. L., additional, Ochner, P., additional, Okhmat, D. N., additional, Papadakis, I., additional, Parks, J. R., additional, Pei, L., additional, Penny, M. T., additional, Pizzella, A., additional, Poleski, R., additional, Pott, J.-U., additional, Rafter, S. E., additional, Rix, H.-W., additional, Runnoe, J., additional, Saylor, D. A., additional, Schimoia, J. S., additional, Scott, B., additional, Sergeev, S. G., additional, Shappee, B. J., additional, Shivvers, I., additional, Siegel, M., additional, Simonian, G. V., additional, Siviero, A., additional, Skielboe, A., additional, Somers, G., additional, Spencer, M., additional, Starkey, D., additional, Stevens, D. J., additional, Sung, H.-I., additional, Tayar, J., additional, Tejos, N., additional, Turner, C. S., additional, Uttley, P., additional, Van Saders, J ., additional, Vaughan, S. A., additional, Vican, L., additional, Villanueva, S., additional, Villforth, C., additional, Weiss, Y., additional, Woo, J.-H., additional, Yan, H., additional, Young, S., additional, Yuk, H., additional, Zheng, W., additional, Zhu, W., additional, and Zu, Y., additional

Published
2020
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20. VERITAS Discovery of VHE Emission from the Radio Galaxy 3C 264: A Multiwavelength Study

Author

Archer, A., primary, Benbow, W., additional, Bird, R., additional, Brill, A., additional, Buchovecky, M., additional, Buckley, J. H., additional, Carini, M. T., additional, Christiansen, J. L., additional, Chromey, A. J., additional, Daniel, M. K., additional, Errando, M., additional, Falcone, A., additional, Feng, Q., additional, Fortin, P., additional, Fortson, L., additional, Furniss, A., additional, Gent, A., additional, Georganopoulos, M., additional, Gillanders, G. H., additional, Giuri, C., additional, Gueta, O., additional, Hanna, D., additional, Hassan, T., additional, Hervet, O., additional, Holder, J., additional, Hughes, G., additional, Humensky, T. B., additional, Kaaret, P., additional, Kertzman, M., additional, Kieda, D., additional, Krennrich, F., additional, Lang, M. J., additional, Lin, T. T. Y., additional, Lister, M. L., additional, Lundy, M., additional, Maier, G., additional, Meyer, E., additional, Moriarty, P., additional, Mukherjee, R., additional, Nieto, D., additional, Nievas-Rosillo, M., additional, O’Brien, S., additional, Ong, R. A., additional, Pfrang, K., additional, Pohl, M., additional, Prado, R. R., additional, Pueschel, E., additional, Quinn, J., additional, Ragan, K., additional, Ramirez, K., additional, Reynolds, P. T., additional, Ribeiro, D., additional, Richards, G. T., additional, Roache, E., additional, Rulten, C., additional, Ryan, J. L., additional, Sadun, A., additional, Santander, M., additional, Scott, S. S., additional, Sembroski, G. H., additional, Shahinyan, K., additional, Shang, R., additional, Stevenson, B., additional, Vassiliev, V. V., additional, Wakely, S. P., additional, Weinstein, A., additional, Wilcox, P., additional, Wilhelm, A., additional, Williams, D. A., additional, and Williamson, T. J, additional

Published
2020
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21. The Great Markarian 421 flare of 2010 February:multiwavelength variability and correlation studies

Author

Abeysekara, A. U. (A. U.), Benbow, W. (W.), Bird, R. (R.), Brill, A. (A.), Brose, R. (R.), Buchovecky, M. (M.), Buckley, J. H. (J. H.), Christiansen, J. L. (J. L.), Chromey, A. J. (A. J.), Daniel, M. K. (M. K.), Dumm, J. (J.), Falcone, A. (A.), Feng, Q. (Q.), Finley, J. P. (J. P.), Fortson, L. (L.), Furniss, A. (A.), Galante, N. (N.), Gent, A. (A.), Gillanders, G. H. (G. H.), Giuri, C. (C.), Gueta, O. (O.), Hassan, T. (T.), Hervet, O. (O.), Holder, J. (J.), Hughes, G. (G.), Humensky, T. B. (T. B.), Johnson, C. A. (C. A.), Kaaret, P. (P.), Kar, P. (P.), Kelley-Hoskins, N. (N.), Kertzman, M. (M.), Kieda, D. (D.), Krause, M. (M.), Krennrich, F. (F.), Kumar, S. (S.), Lang, M. J. (M. J.), Moriarty, P. (P.), Mukherjee, R. (R.), Nelson, T. (T.), Nieto, D. (D.), Nievas-Rosillo, M. (M.), O'Brien, S. (S.), Ong, R. A. (R. A.), Otte, A. N. (A. N.), Park, N. (N.), Petrashyk, A. (A.), Pichel, A. (A.), Pohl, M. (M.), Prado, R. R. (R. R.), Pueschel, E. (E.), Quinn, J. (J.), Ragan, K. (K.), Reynolds, P. T. (P. T.), Richards, G. T. (G. T.), Roache, E. (E.), Rovero, A. C. (A. C.), Rulten, C. (C.), Sadeh, I. (I), Santander, M. (M.), Sembroski, G. H. (G. H.), Shahinyan, K. (K.), Stevenson, B. (B.), Sushch, I. (I), Tyler, J. (J.), Vassiliev, V. V. (V. V.), Wakely, S. P. (S. P.), Weinstein, A. (A.), Wells, R. M. (R. M.), Wilcox, P. (P.), Wilhelm, A. (A.), Williams, D. A. (D. A.), Zitzer, B. (B.), Acciari, V. A. (V. A.), Ansoldi, S. (S.), Antonelli, L. A. (L. A.), Engels, A. A. (A. Arbet), Baack, D. (D.), Babic, A. (A.), Banerjee, B. (B.), Barres de Almeida, U. (U.), Barrio, J. A. (J. A.), Becerra Gonzalez, J. (J.), Bednarek, W. (W.), Bellizzi, L. (L.), Bernardini, E. (E.), Berti, A. (A.), Besenrieder, J. (J.), Bhattacharyya, W. (W.), Bigongiari, C. (C.), Biland, A. (A.), Blanch, O. (O.), Bonnoli, G. (G.), Busetto, G. (G.), Carosi, R. (R.), Ceribella, G. (G.), Chai, Y. (Y.), Cikota, S. (S.), Colak, S. M. (S. M.), Colin, U. (U.), Colombo, E. (E.), Contreras, J. L. (J. L.), Cortina, J. (J.), Covino, S. (S.), D'Elia, V. (V), Vela, P. (P.), Dazzi, F. (F.), De Angelis, A. (A.), De Lotto, B. (B.), Delfino, M. (M.), Delgado, J. (J.), Di Pierro, F. (F.), Souto Espinera, E. (E.), Prester, D. D. (D. Dominis), Dorner, D. (D.), Doro, M. (M.), Einecke, S. (S.), Elsaesser, D. (D.), Ramazani, V. F. (V. Fallah), Fattorini, A. (A.), Fernandez-Barral, A. (A.), Ferrara, G. (G.), Fidalgo, D. (D.), Foffano, L. (L.), Fonseca, M. V. (M., V), Font, L. (L.), Fruck, C. (C.), Galindo, D. (D.), Gallozzi, S. (S.), Garcia Lopez, R. J. (R. J.), Garczarczyk, M. (M.), Gasparyan, S. (S.), Gaug, M. (M.), Godinovic, N. (N.), Green, D. (D.), Guberman, D. (D.), Hadasch, D. (D.), Hahn, A. (A.), Herrera, J. (J.), Hoang, J. (J.), Hrupec, D. (D.), Inoue, S. (S.), Ishio, K. (K.), Iwamura, Y. (Y.), Kubo, H. (H.), Kushida, J. (J.), Lamastra, A. (A.), Lelas, D. (D.), Leone, F. (F.), Lindfors, E. (E.), Lombardi, S. (S.), Longo, F. (F.), Lopez, M. (M.), Lopez-Coto, R. (R.), Lopez-Oramas, A. (A.), Machado de Oliveira Fraga, B. (B.), Maggio, C. (C.), Majumdar, P. (P.), Makariev, M. (M.), Mallamaci, M. (M.), Maneva, G. (G.), Manganaro, M. (M.), Mannheim, K. (K.), Maraschi, L. (L.), Mariotti, M. (M.), Martinez, M. (M.), Masuda, S. (S.), Mazin, D. (D.), Miceli, D. (D.), Minev, M. (M.), Miranda, J. M. (J. M.), Mirzoyan, R. (R.), Molina, E. (E.), Moralejo, A. (A.), Morcuende, D. (D.), Moreno, V. (V), Moretti, E. (E.), Munar-Adrover, P. (P.), Neustroev, V. (V), Niedzwiecki, A. (A.), Nievas Rosillo, M. (M.), Nigro, C. (C.), Nilsson, K. (K.), Ninci, D. (D.), Nishijima, K. (K.), Noda, K. (K.), Nogues, L. (L.), Noethe, M. (M.), Paiano, S. (S.), Palacio, J. (J.), Palatiello, M. (M.), Paneque, D. (D.), Paoletti, R. (R.), Paredes, J. M. (J. M.), Penil, P. (P.), Peresano, M. (M.), Persic, M. (M.), Moroni, P. G. (P. G. Prada), Prandini, E. (E.), Puljak, I. (I), Rhode, W. (W.), Ribo, M. (M.), Rico, J. (J.), Righi, C. (C.), Rugliancich, A. (A.), Saha, L. (L.), Sahakyan, N. (N.), Saito, T. (T.), Satalecka, K. (K.), Schweizer, T. (T.), Sitarek, J. (J.), Snidaric, I. (I), Sobczynska, D. (D.), Somero, A. (A.), Stamerra, A. (A.), Strom, D. (D.), Strzys, M. (M.), Sun, S. (S.), Suric, T. (T.), Tavecchio, F. (F.), Temnikov, P. (P.), Terzic, T. (T.), Teshima, M. (M.), Torres-Alba, N. (N.), Tsujimoto, S. (S.), van Scherpenberg, J. (J.), Vanzo, G. (G.), Vazquez Acosta, M. (M.), Vovk, I. (I), Will, M. (M.), Zaric, D. (D.), Aller, H. D. (H. D.), Aller, M. F. (M. F.), Carini, M. T. (M. T.), Horan, D. (D.), Jordan, B. (B.), Jorstad, S. G. (S. G.), Kurtanidze, O. M. (O. M.), Kurtanidze, S. O. (S. O.), Lahteenmaki, A. (A.), Larionov, V. M. (V. M.), Larionova, E. G. (E. G.), Madejski, G. (G.), Marscher, A. P. (A. P.), Max-Moerbeck, W. (W.), Moody, J. W. (J. Ward), Morozova, D. A. (D. A.), Nikolashvili, M. G. (M. G.), Raiteri, C. M. (C. M.), Readhead, A. C. (A. C. S.), Richards, J. L. (J. L.), Sadun, A. C. (A. C.), Sakamoto, T. (T.), Sigua, L. A. (L. A.), Smith, P. S. (P. S.), Talvikki, H. (H.), Tammi, J. (J.), Tornikoski, M. (M.), Troitsky, I. S. (I. S.), and Villata, M. (M.)

Subjects
Gamma-ray astronomy, Astrophysics::High Energy Astrophysical Phenomena, Time domain astronomy, BL Lacertae objects, Markarian galaxies, Relativistic jets, High energy astrophysics, Blazars
Abstract

We report on variability and correlation studies using multiwavelength observations of the blazar Mrk 421 during the month of 2010 February, when an extraordinary flare reaching a level of ~27 Crab Units above 1 TeV was measured in very high energy (VHE) γ-rays with the Very Energetic Radiation Imaging Telescope Array System (VERITAS) observatory. This is the highest flux state for Mrk 421 ever observed in VHE γ-rays. Data are analyzed from a coordinated campaign across multiple instruments, including VHE γ-ray (VERITAS, Major Atmospheric Gamma-ray Imaging Cherenkov), high-energy γ-ray (Fermi-LAT), X-ray (Swift, Rossi X-ray Timing Experiment, MAXI), optical (including the GASP-WEBT collaboration and polarization data), and radio (Metsähovi, Owens Valley Radio Observatory, University of Michigan Radio Astronomy Observatory). Light curves are produced spanning multiple days before and after the peak of the VHE flare, including over several flare “decline“ epochs. The main flare statistics allow 2 minute time bins to be constructed in both the VHE and optical bands enabling a cross-correlation analysis that shows evidence for an optical lag of ~25–55 minutes, the first time-lagged correlation between these bands reported on such short timescales. Limits on the Doppler factor (δ ≳ 33) and the size of the emission region (δ⁻¹ RB ≲ × 10¹³ cm) are obtained from the fast variability observed by VERITAS during the main flare. Analysis of 10 minute binned VHE and X-ray data over the decline epochs shows an extraordinary range of behavior in the flux–flux relationship, from linear to quadratic to lack of correlation to anticorrelation. Taken together, these detailed observations of an unprecedented flare seen in Mrk 421 are difficult to explain with the classic single-zone synchrotron self-Compton model.

Published
2020

23. Day-Scale Variability of 3C 279 and Searches for Correlations in Gamma-Ray, X-Ray and Optical Bands

Author

Hartman, R. C, Villata, M, Balonek, T. J, Bertsch, D. L, Bock, H, Boettcher, M, Carini, M. T, Collmar, W, DeFrancesco, G, Ferrera, E. C, and White, Nicholas E

Subjects
Astronomy
Abstract

Light curves of 3C 279 are presented in optical (R-band), X-rays (RXTE/PCA), and gamma rays (CGRO/EGRET) for 1999 Jan-Feb and 2000 Jan-Mar. During both of those epochs the gamma-ray levels were high, and all three observed bands demonstrated substantial variation, on time scales as short as one day. Correlation analyses provided no consistent pattern, although a rather significant optical/gamma-ray correlation was seen in 1999, with a gamma-ray lag of approximately 2.5 days, and there are other suggestions of correlations in the light curves. For comparison, correlation analysis is also presented for the gamma-ray and X-ray light curves during the large gamma-ray flare in 1996 Feb and the two gamma-bright weeks leading up to it; the correlation at that time was strong, with a gamma-ray/X-ray offset of no more than one day.

Published
2001

24. Ground-Based Observations of PKS2155-304 in November 1991

Author

Blecha, A., primary, Courvoisier, T. J.-L., additional, Aller, H. D., additional, Aller, M. F., additional, Bouchet, P., additional, Bratschi, P., additional, Carini, M. T., additional, Donahue, M., additional, Feigelson, E. D., additional, Filippenko, A. V., additional, Glass, I. S., additional, Heidt, J., additional, Hughes, P. A., additional, Kollgaard, R. I., additional, Matheson, T., additional, Miller, H. R., additional, Noble, J. C., additional, Smith, P. S., additional, and Wagner, S., additional

Published
1994
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25. Space Telescope and Optical Reverberation Mapping Project. VIII. Time Variability of Emission and Absorption in NGC 5548 Based on Modeling the Ultraviolet Spectrum

Author

Kriss, G. A., primary, De Rosa, G., additional, Ely, J., additional, Peterson, B. M., additional, Kaastra, J., additional, Mehdipour, M., additional, Ferland, G. J., additional, Dehghanian, M., additional, Mathur, S., additional, Edelson, R., additional, Korista, K. T., additional, Arav, N., additional, Barth, A. J., additional, Bentz, M. C., additional, Brandt, W. N., additional, Crenshaw, D. M., additional, Bontà, E. Dalla, additional, Denney, K. D., additional, Done, C., additional, Eracleous, M., additional, Fausnaugh, M. M., additional, Gardner, E., additional, Goad, M. R., additional, Grier, C. J., additional, Horne, Keith, additional, Kochanek, C. S., additional, McHardy, I. M., additional, Netzer, H., additional, Pancoast, A., additional, Pei, L., additional, Pogge, R. W., additional, Proga, D., additional, Silva, C., additional, Tejos, N., additional, Vestergaard, M., additional, Adams, S. M., additional, Anderson, M. D., additional, Arévalo, P., additional, Beatty, T G., additional, Behar, E., additional, Bennert, V. N., additional, Bianchi, S., additional, Bigley, A., additional, Bisogni, S., additional, Boissay-Malaquin, R., additional, Borman, G. A., additional, Bottorff, M. C., additional, Breeveld, A. A., additional, Brotherton, M., additional, Brown, J. E., additional, Brown, J. S., additional, Cackett, E. M., additional, Canalizo, G., additional, Cappi, M., additional, Carini, M. T., additional, Clubb, K. I., additional, Comerford, J. M., additional, Coker, C. T., additional, Corsini, E. M., additional, Costantini, E., additional, Croft, S., additional, Croxall, K. V., additional, Deason, A. J., additional, De Lorenzo-Cáceres, A., additional, De Marco, B., additional, Dietrich, M., additional, Di Gesu, L., additional, Ebrero, J., additional, Evans, P. A., additional, Filippenko, A. V., additional, Flatland, K., additional, Gates, E. L., additional, Gehrels, N., additional, Geier, S., additional, Gelbord, J. M., additional, Gonzalez, L., additional, Gorjian, V., additional, Grupe, D., additional, Gupta, A., additional, Hall, P. B., additional, Henderson, C. B., additional, Hicks, S., additional, Holmbeck, E., additional, Holoien, T. W.-S., additional, Hutchison, T. A., additional, Im, M., additional, Jensen, J. J., additional, Johnson, C. A., additional, Joner, M. D., additional, Kaspi, S., additional, Kelly, B. C., additional, Kelly, P. L., additional, Kennea, J. A., additional, Kim, M., additional, Kim, S. C., additional, Kim, S. Y., additional, King, A., additional, Klimanov, S. A., additional, Krongold, Y., additional, Lau, M. W., additional, Lee, J. C., additional, Leonard, D. C., additional, Li, Miao, additional, Lira, P., additional, Lochhaas, C., additional, Ma, Zhiyuan, additional, MacInnis, F., additional, Malkan, M. A., additional, Manne-Nicholas, E. R., additional, Matt, G., additional, Mauerhan, J. C., additional, McGurk, R., additional, Montuori, C., additional, Morelli, L., additional, Mosquera, A., additional, Mudd, D., additional, Müller-Sánchez, F., additional, Nazarov, S. V., additional, Norris, R. P., additional, Nousek, J. A., additional, Nguyen, M. L., additional, Ochner, P., additional, Okhmat, D. N., additional, Paltani, S., additional, Parks, J. R., additional, Pinto, C., additional, Pizzella, A., additional, Poleski, R., additional, Ponti, G., additional, Pott, J.-U., additional, Rafter, S. E., additional, Rix, H.-W., additional, Runnoe, J., additional, Saylor, D. A., additional, Schimoia, J. S., additional, Schnülle, K., additional, Scott, B., additional, Sergeev, S. G., additional, Shappee, B. J., additional, Shivvers, I., additional, Siegel, M., additional, Simonian, G. V., additional, Siviero, A., additional, Skielboe, A., additional, Somers, G., additional, Spencer, M., additional, Starkey, D., additional, Stevens, D. J., additional, Sung, H.-I., additional, Tayar, J., additional, Teems, K. G., additional, Treu, T., additional, Turner, C. S., additional, Uttley, P., additional, Van Saders, J ., additional, Vican, L., additional, Villforth, C., additional, Villanueva Jr., S., additional, Walton, D. J., additional, Waters, T., additional, Weiss, Y., additional, Woo, J.-H., additional, Yan, H., additional, Yuk, H., additional, Zheng, W., additional, Zhu, W., additional, and Zu, Y., additional

Published
2019
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26. Observations of a Major Outburst of BL Lacertae in the Active Galactic Nuclei Monitoring Program in the Center for Automated Space Science

Author

Carini, M. T, Hackney, K. R, Clements, S. D, Culler, R. C, Hackney, R. L, Noble, J. C, Gelderman, R. G, Scott, R. L, and McGruder, C. H., III

Subjects
Space Radiation
Abstract

BL Lacertae (BL Lac) is the prototype for a class of Active Galactic Nuclei (AGN) known as BL Lac objects. These objects are characterized by a featureless optical continuum that is both highly polarized and extremely variable. Historically, this object is known to have an optical variability range of 5 magnitudes (Webb, et al., 1987, Carini, et al. 1992) and exhibits episodic periods in which the source is observed to be bright (V = 12.0) and other periods when the source is observed to be quite faint (V = 16.5). In May, 1997, we found, in the course of our routine monitoring of these objects, that BL Lac was in an elevated state, with a V magnitude peaking near V = 12.5. The purpose of this paper is to report on our observations of the behavior of the optical continuum flux of BL Lac during this major outburst.

Published
1998

28. Spiral ARMS in Galaxies with Counter-Rotating Stellar Disks

Author

Howard, S, Carini, M. T, Byrd, G. G, and Lester, S

Abstract

Spectroscopic observations by Rubin and other indicate that the S type galaxies NGC 4550, NGC 7217, and NGC 4138 have two-way disks with a substantial portion of the stellar disk orbiting opposite the direction of the rest...However, in 1978, Zang and Hohl found via simulations that one-fold instabilities were enhanced in a two-way disk with no halo...Using a self-gravitating disk with a flat rotation curve, we redo Zang and Hohl's isolated simulations but with more particles plus varying amounts of an inert halo component.

Published
1996

29. Multiwavelength monitoring of the BL Lacertae object PKS 2155-304. 3: Ground-based observations in 1991 November

Author

Courvoisier, T. J.-L, Blecha, A, Bouchet, P, Bratschi, P, Carini, M. T, Donahue, M, Edelson, R, Feigelson, E. D, Filippenko, A. V, and Glass, I. S

Subjects
Astronomy
Abstract

We present ground-based observations of the BL Lac object PKS 2155-304 during 1991 November. These data were obtained as part of a large international campaign of observations spanning the electro-magnetic spectrum from the radio waves to the X-rays. The data presented here include radio and UBVRI fluxes, as well as optical polarimetry. The U to I data show the same behavior in all bands and that only upper limits to any lag can be deduced from the cross-correlation of the light curves. The spectral slope in the U-I domain remained constant on all epochs but 2. There is no correlation between changes in the spectral slope and large variations in the total or polarized flux. The radio flux variations did not follow the same pattern of variability as the optical and infrared fluxes. The polarized flux varied by a larger factor than the total flux. The variations of the polarized flux are poorly correlated with those of the total flux in the optical (and hence UV domain; see the accompanying paper by Edelson et al.) nor with those of the soft X-rays. We conclude that the variability of PKS 2155-304 in the optical and near-infrared spectral domains are easier to understand in the context of variable geometry or bulk Lorentz factor than of variable electron acceleration and cooling rates.

Published
1995
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30. The timescales of the optical variability of blazars. III - OJ 287 and BL Lacertae

Author

Carini, M. T, Miller, H. R, Noble, J. C, and Goodrich, B. D

Subjects
Astrophysics
Abstract

The BL Lacertae objects OJ 287 and BL Lac have been photometrically monitored in an effort to study the nature of optical variations which may occur on timescales ranging from years to less than a day. The results of ten years of photometric monitoring of these two objects show variations which are consistent with those reported by other authors. No strong dependence of color with source brightness was detected, although both sources exhibited a weak tendency to be bluer when brighter. Microvariability was observed for both objects; variations as large as 0.1 mag/hr were observed for BL Lac and changes as large as 0.08 mag/hr were observed for OJ 287. No evidence for a periodicity was found in the observed variations of either object.

Published
1992
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31. A search for microvariability in five OVV quasars

Author

Miller, H. R, Noble, J. C, Carini, M. T, Urry, C. M, Sokoloski, J, and Howell, S. B

Subjects
Astrophysics
Abstract

We present results of monitoring a sample of five OVV qausars in an effort to determine if these types of AGNs exhibit microvariability similar to that detected for BL Lacertae objects. Three of the five quasars investigated clearly exhibited microvariability. The timescales for the variations for both BL Lacertae objects and OVV quasars are similar which suggests that the radiation is generated in similar spatial volumes. These variations are consistent with the results of models which explain the observed microvariability as the result of excess emission produced by flares or hot spots randomly appearing and disappearing on the accretion disks around supermassive black holes.

Published
1992

33. The long term optical variability of PKS 2201 + 044

Author

Carini, M. T., Miller, H. R., Wilson, J. W., Araki, H., editor, Ehlers, J., editor, Hepp, K., editor, Kippenhahn, R., editor, Weidenmüller, H. A., editor, Wess, J., editor, Zittartz, J., editor, Beiglböck, W., editor, Miller, H. Richard, editor, and Wiita, Paul J., editor

Published
1988
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34. Multi-Wavelength Observations of the Blazar 1ES 1011+496 in Spring 2008

Author

Ahnen, M. L., Ansoldi, S., Antonelli, L. A., Antoranz, P., Babic, A., Banerjee, B., Bangale, P., De Almeida, U. Barres, Barrio, J. A., González, J. Becerra, Bednarek, W., Bernardini, E., Biasuzzi, B., Biland, A., Blanch, O., Bonnefoy, S., Bonnoli, G., Borracci, F., Bretz, T., Carmona, E., Carosi, A., Chatterjee, A., Clavero, R., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., Da Vela, P., Dazzi, F., De Angelis, A., De Caneva, G., De Lotto, B., Wilhelmi, E. De O Na, Mendez, C. Delgado, Pierro, F. Di, Prester, D. Dominis, Dorner, D., Doro, M., Einecke, S., Elsaesser, D., Fernández-Barral, A., Fidalgo, D., Fonseca, M. V., Font, L., Frantzen, K., Fruck, C., Galindo, D., López, R. J. García, Garczarczyk, M., Terrats, D. Garrido, Gaug, M., Giammaria, P., Godinović, N., Muñoz, A. González, Guberman, D., Hanabata, Y., Hayashida, M., Herrera, J., Hose, J., Hrupec, D., Hughes, G., Idec, W., Kodani, K., Konno, Y., Kubo, H., Kushida, J., La Barbera, A., Lelas, D., Lindfors, E., Lombardi, S., Longo, F., López, M., López-Coto, R., López-Oramas, A., Lorenz, E., Majumdar, P., Makariev, M., Mallot, K., Maneva, G., Manganaro, M., Mannheim, K., Maraschi, L., Marcote, B., Mariotti, M., Martínez, M., Mazin, D., Menzel, U., Miranda, J. M., Mirzoyan, R., Moralejo, A., Nakajima, D., Neustroev, V., Niedzwiecki, A., Rosillo, M. Nievas, Nilsson, K., Nishijima, K., Noda, K., Orito, R., Overkemping, A., Paiano, S., Palacio, J., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Paredes-Fortuny, X., Persic, M., Poutanen, J., Moroni, P. G. Prada, Prandini, E., Puljak, I., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Garcia, J. Rodriguez, Rügamer, S., Saito, T., Satalecka, K., Scapin, V., Schultz, C., Schweizer, T., Shore, S. N., Sillanpää, A., Sitarek, J., Snidaric, I., Sobczynska, D., Stamerra, A., Steinbring, T., Strzys, M., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Thaele, J., Torres, D. F., Toyama, T., Treves, A., Verguilov, V., Vovk, I., Ward, J. E., Will, M., Wu, M. H., Zanin, R., Lucarelli, F., Pittori, C., Vercellone, S., Berdyugin, A., Carini, M. T., Lähteenmäki, A., Pasanen, M., Pease, A., Sainio, J., Tornikoski, M., and Walters, R.

Abstract

Monthly notices of the Royal Astronomical Society 459, 2286 - 2298 (2016). doi:10.1093/mnras/stw710, The BL Lac object 1ES 1011+496 was discovered at very high energy (VHE, E > 100GeV) γ-rays by Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) in Spring 2007. Before that the source was little studied in different wavelengths. Therefore, a multiwavelength (MWL) campaign was organized in Spring 2008. Along MAGIC, the MWL campaign included the Metsähovi Radio Observatory, Bell and Kungliga Vetenskapsakademien (KVA) optical telescopes and the Swift and AGILE satellites. MAGIC observations span from 2008 March to May for a total of 27.9 h, of which 19.4 h remained after quality cuts. The light curve showed no significant variability yielding an integral flux above 200 GeV of (1.3 ± 0.3) × 10$^{−11}$ photons cm$^{−2}$ s$^{−1}$. The differential VHE spectrum could be described with a power-law function with a spectral index of 3.3 ± 0.4. Both results were similar to those obtained during the discovery. Swift X-ray Telescope observations revealed an X-ray flare, characterized by a harder-when-brighter trend, as is typical for high synchrotron peak BL Lac objects (HBL). Strong optical variability was found during the campaign, but no conclusion on the connection between the optical and VHE γ-ray bands could be drawn. The contemporaneous spectral energy distribution shows a synchrotron-dominated source, unlike concluded in previous work based on non-simultaneous data, and is well described by a standard one-zone synchrotron self-Compton model. We also performed a study on the source classification. While the optical and X-ray data taken during our campaign show typical characteristics of an HBL, we suggest, based on archival data, that 1ES 1011+496 is actually a borderline case between intermediate and high synchrotron peak frequency BL Lac objects., Published by Oxford Univ. Press, Oxford

Published
2016
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35. Space Telescope and Optical Reverberation Mapping Project. VII. Understanding the Ultraviolet Anomaly in NGC 5548 with X-Ray Spectroscopy

Author

Mathur, S., primary, Gupta, A., additional, Page, K., additional, Pogge, R. W., additional, Krongold, Y., additional, Goad, M. R., additional, Adams, S. M., additional, Anderson, M. D., additional, Arévalo, P., additional, Barth, A. J., additional, Bazhaw, C., additional, Beatty, T. G., additional, Bentz, M. C., additional, Bigley, A., additional, Bisogni, S., additional, Borman, G. A., additional, Boroson, T. A., additional, Bottorff, M. C., additional, Brandt, W. N., additional, Breeveld, A. A., additional, Brown, J. E., additional, Brown, J. S., additional, Cackett, E. M., additional, Canalizo, G., additional, Carini, M. T., additional, Clubb, K. I., additional, Comerford, J. M., additional, Coker, C. T., additional, Corsini, E. M., additional, Crenshaw, D. M., additional, Croft, S., additional, Croxall, K. V., additional, Dalla Bontà, E., additional, Deason, A. J., additional, Denney, K. D., additional, De Lorenzo-Cáceres, A., additional, De Rosa, G., additional, Dietrich, M., additional, Edelson, R., additional, Ely, J., additional, Eracleous, M., additional, Evans, P. A., additional, Fausnaugh, M. M., additional, Ferland, G. J., additional, Filippenko, A. V., additional, Flatland, K., additional, Fox, O. D., additional, Gates, E. L., additional, Gehrels, N., additional, Geier, S., additional, Gelbord, J. M., additional, Gorjian, V., additional, Greene, J. E., additional, Grier, C. J., additional, Grupe, D., additional, Hall, P. B., additional, Henderson, C. B., additional, Hicks, S., additional, Holmbeck, E., additional, Holoien, T. W.-S., additional, Horenstein, D., additional, Horne, Keith, additional, Hutchison, T., additional, Im, M., additional, Jensen, J. J., additional, Johnson, C. A., additional, Joner, M. D., additional, Jones, J., additional, Kaastra, J., additional, Kaspi, S., additional, Kelly, B. C., additional, Kelly, P. L., additional, Kennea, J. A., additional, Kim, M., additional, Kim, S., additional, Kim, S. C., additional, King, A., additional, Klimanov, S. A., additional, Kochanek, C. S., additional, Korista, K. T., additional, Kriss, G. A., additional, Lau, M. W., additional, Lee, J. C., additional, Leonard, D. C., additional, Li, M., additional, Lira, P., additional, Ma, Z., additional, MacInnis, F., additional, Manne-Nicholas, E. R., additional, Malkan, M. A., additional, Mauerhan, J. C., additional, McGurk, R., additional, McHardy, I. M., additional, Montouri, C., additional, Morelli, L., additional, Mosquera, A., additional, Mudd, D., additional, Muller-Sanchez, F., additional, Musso, R., additional, Nazarov, S. V., additional, Netzer, H., additional, Nguyen, M. L., additional, Norris, R. P., additional, Nousek, J. A., additional, Ochner, P., additional, Okhmat, D. N., additional, Ou-Yang, B., additional, Pancoast, A., additional, Papadakis, I., additional, Parks, J. R., additional, Pei, L., additional, Peterson, B. M., additional, Pizzella, A., additional, Poleski, R., additional, Pott, J.-U., additional, Rafter, S. E., additional, Rix, H.-W., additional, Runnoe, J., additional, Saylor, D. A., additional, Schimoia, J. S., additional, Schnülle, K., additional, Sergeev, S. G., additional, Shappee, B. J., additional, Shivvers, I., additional, Siegel, M., additional, Simonian, G. V., additional, Siviero, A., additional, Skielboe, A., additional, Somers, G., additional, Spencer, M., additional, Starkey, D., additional, Stevens, D. J., additional, Sung, H.-I., additional, Tayar, J., additional, Tejos, N., additional, Turner, C. S., additional, Uttley, P., additional, Van Saders, J., additional, Vestergaard, M., additional, Vican, L., additional, Villanueva Jr., S., additional, Villforth, C., additional, Weiss, Y., additional, Woo, J.-H., additional, Yan, H., additional, Young, S., additional, Yuk, H., additional, Zheng, W., additional, Zhu, W., additional, and Zu, Y., additional

Published
2017
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36. Space Telescope and Optical Reverberation Mapping Project. V. Optical Spectroscopic Campaign and Emission-line Analysis for NGC 5548

Author

Pei, L., primary, Fausnaugh, M. M., additional, Barth, A. J., additional, Peterson, B. M., additional, Bentz, M. C., additional, De Rosa, G., additional, Denney, K. D., additional, Goad, M. R., additional, Kochanek, C. S., additional, Korista, K. T., additional, Kriss, G. A., additional, Pogge, R. W., additional, Bennert, V. N., additional, Brotherton, M., additional, Clubb, K. I., additional, Dalla Bontà, E., additional, Filippenko, A. V., additional, Greene, J. E., additional, Grier, C. J., additional, Vestergaard, M., additional, Zheng, W., additional, Adams, Scott M., additional, Beatty, Thomas G., additional, Bigley, A., additional, Brown, Jacob E., additional, Brown, Jonathan S., additional, Canalizo, G., additional, Comerford, J. M., additional, Coker, Carl T., additional, Corsini, E. M., additional, Croft, S., additional, Croxall, K. V., additional, Deason, A. J., additional, Eracleous, Michael, additional, Fox, O. D., additional, Gates, E. L., additional, Henderson, C. B., additional, Holmbeck, E., additional, Holoien, T. W.-S., additional, Jensen, J. J., additional, Johnson, C. A., additional, Kelly, P. L., additional, Kim, S., additional, King, A., additional, Lau, M. W., additional, Li, Miao, additional, Lochhaas, Cassandra, additional, Ma, Zhiyuan, additional, Manne-Nicholas, E. R., additional, Mauerhan, J. C., additional, Malkan, M. A., additional, McGurk, R., additional, Morelli, L., additional, Mosquera, Ana, additional, Mudd, Dale, additional, Sanchez, F. Muller, additional, Nguyen, M. L., additional, Ochner, P., additional, Ou-Yang, B., additional, Pancoast, A., additional, Penny, Matthew T., additional, Pizzella, A., additional, Poleski, Radosław, additional, Runnoe, Jessie, additional, Scott, B., additional, Schimoia, Jaderson S., additional, Shappee, B. J., additional, Shivvers, I., additional, Simonian, Gregory V., additional, Siviero, A., additional, Somers, Garrett, additional, Stevens, Daniel J., additional, Strauss, M. A., additional, Tayar, Jamie, additional, Tejos, N., additional, Treu, T., additional, Van Saders, J., additional, Vican, L., additional, Villanueva, S., additional, Yuk, H., additional, Zakamska, N. L., additional, Zhu, W., additional, Anderson, M. D., additional, Arévalo, P., additional, Bazhaw, C., additional, Bisogni, S., additional, Borman, G. A., additional, Bottorff, M. C., additional, Brandt, W. N., additional, Breeveld, A. A., additional, Cackett, E. M., additional, Carini, M. T., additional, Crenshaw, D. M., additional, De Lorenzo-Cáceres, A., additional, Dietrich, M., additional, Edelson, R., additional, Efimova, N. V., additional, Ely, J., additional, Evans, P. A., additional, Ferland, G. J., additional, Flatland, K., additional, Gehrels, N., additional, Geier, S., additional, Gelbord, J. M., additional, Grupe, D., additional, Gupta, A., additional, Hall, P. B., additional, Hicks, S., additional, Horenstein, D., additional, Horne, Keith, additional, Hutchison, T., additional, Im, M., additional, Joner, M. D., additional, Jones, J., additional, Kaastra, J., additional, Kaspi, S., additional, Kelly, B. C., additional, Kennea, J. A., additional, Kim, M., additional, Kim, S. C., additional, Klimanov, S. A., additional, Lee, J. C., additional, Leonard, D. C., additional, Lira, P., additional, MacInnis, F., additional, Mathur, S., additional, McHardy, I. M., additional, Montouri, C., additional, Musso, R., additional, Nazarov, S. V., additional, Netzer, H., additional, Norris, R. P., additional, Nousek, J. A., additional, Okhmat, D. N., additional, Papadakis, I., additional, Parks, J. R., additional, Pott, J.-U., additional, Rafter, S. E., additional, Rix, H.-W., additional, Saylor, D. A., additional, Schnülle, K., additional, Sergeev, S. G., additional, Siegel, M., additional, Skielboe, A., additional, Spencer, M., additional, Starkey, D., additional, Sung, H.-I., additional, Teems, K. G., additional, Turner, C. S., additional, Uttley, P., additional, Villforth, C., additional, Weiss, Y., additional, Woo, J.-H., additional, Yan, H., additional, Young, S., additional, and Zu, Y., additional

Published
2017
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37. SPACE TELESCOPE AND OPTICAL REVERBERATION MAPPING PROJECT. VI. REVERBERATING DISK MODELS FOR NGC 5548

Author

Starkey, D., Horne, Keith, Fausnaugh, M. M., Peterson, B. M., Bentz, M. C., Kochanek, C. S., Denney, K. D., Edelson, R., Goad, M. R., De Rosa, G., Anderson, M. D., Arevalo, P., Barth, A. J., Bazhaw, C., Borman, G. A., Boroson, T. A., Bottorff, M. C., Brandt, W. N., Breeveld, A. A., Cackett, E. M., Carini, M. T., Croxall, K. V., Crenshaw, D. M., Dalla Bonta, E., De Lorenzo-Caceres, A., Dietrich, M., Efimova, N. V., Ely, J., Evans, P. A., Filippenko, A. V., Flatland, K., Gehrels, N., Geier, S., Gelbord, J. M., Gonzalez, L., Gorjian, V., Grier, C. J., Grupe, D., Hall, P. B., Hicks, S., Horenstein, D., Hutchison, T., Im, M., Jensen, J. J., Joner, M. D., Jones, J., Kaastra, J., Kaspi, S., Kelly, B. C., Kennea, J. A., Kim, S. C., Kim, M., Klimanov, S. A., Korista, K. T., Kriss, G. A., Lee, J. C., Leonard, D. C., Lira, P., MacInnis, F., Manne-Nicholas, E. R., Mathur, S., McHardy, I. M., Montouri, C., Musso, R., Nazarov, S. V., Norris, R. P., Nousek, J. A., Okhmat, D. N., Pancoast, A., Parks, J. R., Pei, L., Pogge, R. W., Pott, J-U, Rafter, S. E., Rix, H-W, Saylor, D. A., Schimoia, J. S., Schnuelle, K., Sergeev, S. G., Siegel, M. H., Spencer, M., Sung, H-I, Teems, K. G., Turner, C. S., Uttley, P., Vestergaard, M., Villforth, C., Weiss, Y., Woo, J-H, Yan, H., Young, S., Zheng, W., Zu, Y., Starkey, D., Horne, Keith, Fausnaugh, M. M., Peterson, B. M., Bentz, M. C., Kochanek, C. S., Denney, K. D., Edelson, R., Goad, M. R., De Rosa, G., Anderson, M. D., Arevalo, P., Barth, A. J., Bazhaw, C., Borman, G. A., Boroson, T. A., Bottorff, M. C., Brandt, W. N., Breeveld, A. A., Cackett, E. M., Carini, M. T., Croxall, K. V., Crenshaw, D. M., Dalla Bonta, E., De Lorenzo-Caceres, A., Dietrich, M., Efimova, N. V., Ely, J., Evans, P. A., Filippenko, A. V., Flatland, K., Gehrels, N., Geier, S., Gelbord, J. M., Gonzalez, L., Gorjian, V., Grier, C. J., Grupe, D., Hall, P. B., Hicks, S., Horenstein, D., Hutchison, T., Im, M., Jensen, J. J., Joner, M. D., Jones, J., Kaastra, J., Kaspi, S., Kelly, B. C., Kennea, J. A., Kim, S. C., Kim, M., Klimanov, S. A., Korista, K. T., Kriss, G. A., Lee, J. C., Leonard, D. C., Lira, P., MacInnis, F., Manne-Nicholas, E. R., Mathur, S., McHardy, I. M., Montouri, C., Musso, R., Nazarov, S. V., Norris, R. P., Nousek, J. A., Okhmat, D. N., Pancoast, A., Parks, J. R., Pei, L., Pogge, R. W., Pott, J-U, Rafter, S. E., Rix, H-W, Saylor, D. A., Schimoia, J. S., Schnuelle, K., Sergeev, S. G., Siegel, M. H., Spencer, M., Sung, H-I, Teems, K. G., Turner, C. S., Uttley, P., Vestergaard, M., Villforth, C., Weiss, Y., Woo, J-H, Yan, H., Young, S., Zheng, W., and Zu, Y.

Published
2017

38. The optical variability of Arakelian 120, 1977–1987

Author

Wilson, J. W., Miller, H. R., Carini, M. T., Araki, H., editor, Ehlers, J., editor, Hepp, K., editor, Kippenhahn, R., editor, Weidenmüller, H. A., editor, Wess, J., editor, Zittartz, J., editor, Beiglböck, W., editor, Miller, H. Richard, editor, and Wiita, Paul J., editor

Published
1988
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40. SPACE TELESCOPE AND OPTICAL REVERBERATION MAPPING PROJECT.VI. REVERBERATING DISK MODELS FOR NGC 5548

Author

Starkey, D., primary, Horne, Keith, additional, Fausnaugh, M. M., additional, Peterson, B. M., additional, Bentz, M. C., additional, Kochanek, C. S., additional, Denney, K. D., additional, Edelson, R., additional, Goad, M. R., additional, Rosa, G. De, additional, Anderson, M. D., additional, Arévalo, P., additional, Barth, A. J., additional, Bazhaw, C., additional, Borman, G. A., additional, Boroson, T. A., additional, Bottorff, M. C., additional, Brandt, W. N., additional, Breeveld, A. A., additional, Cackett, E. M., additional, Carini, M. T., additional, Croxall, K. V., additional, Crenshaw, D. M., additional, Bontà, E. Dalla, additional, Lorenzo-Cáceres, A. De, additional, Dietrich, M., additional, Efimova, N. V., additional, Ely, J., additional, Evans, P. A., additional, Filippenko, A. V., additional, Flatland, K., additional, Gehrels, N., additional, Geier, S., additional, Gelbord, J. M., additional, Gonzalez, L., additional, Gorjian, V., additional, Grier, C. J., additional, Grupe, D., additional, Hall, P. B., additional, Hicks, S., additional, Horenstein, D., additional, Hutchison, T., additional, Im, M., additional, Jensen, J. J., additional, Joner, M. D., additional, Jones, J., additional, Kaastra, J., additional, Kaspi, S., additional, Kelly, B. C., additional, Kennea, J. A., additional, Kim, S. C., additional, Kim, M., additional, Klimanov, S. A., additional, Korista, K. T., additional, Kriss, G. A., additional, Lee, J. C., additional, Leonard, D. C., additional, Lira, P., additional, MacInnis, F., additional, Manne-Nicholas, E. R., additional, Mathur, S., additional, McHardy, I. M., additional, Montouri, C., additional, Musso, R., additional, Nazarov, S. V., additional, Norris, R. P., additional, Nousek, J. A., additional, Okhmat, D. N., additional, Pancoast, A., additional, Parks, J. R., additional, Pei, L., additional, Pogge, R. W., additional, Pott, J.-U., additional, Rafter, S. E., additional, Rix, H.-W., additional, Saylor, D. A., additional, Schimoia, J. S., additional, Schnülle, K., additional, Sergeev, S. G., additional, Siegel, M. H., additional, Spencer, M., additional, Sung, H.-I., additional, Teems, K. G., additional, Turner, C. S., additional, Uttley, P., additional, Vestergaard, M., additional, Villforth, C., additional, Weiss, Y., additional, Woo, J.-H., additional, Yan, H., additional, Young, and S., additional, Zheng, W., additional, and Zu, Y., additional

Published
2017
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41. Space Telescope and Optical Reverberation Mapping Project. III. Optical Continuum Emission and Broadband Time Delays in NGC 5548

Author

Fausnaugh, M. M., Denney, Kelly Dianne, Barth, A.J., Bentz, M.C., Bottorff, M. C., Carini, M. T., Croxall, K. V., De Rosa, G., Goad, M. R., Horne, K., Kaspi, S., Vestergaard, Marianne, Fausnaugh, M. M., Denney, Kelly Dianne, Barth, A.J., Bentz, M.C., Bottorff, M. C., Carini, M. T., Croxall, K. V., De Rosa, G., Goad, M. R., Horne, K., Kaspi, S., and Vestergaard, Marianne

Published
2016

42. SPACE TELESCOPE AND OPTICAL REVERBERATION MAPPING PROJECT. IV. ANOMALOUS BEHAVIOR OF THE BROAD ULTRAVIOLET EMISSION LINES IN NGC 5548

Author

Goad, M. R., primary, Korista, K. T., additional, Rosa, G. De, additional, Kriss, G. A., additional, Edelson, R., additional, Barth, A. J., additional, Ferland, G. J., additional, Kochanek, C. S., additional, Netzer, H., additional, Peterson, B. M., additional, Bentz, M. C., additional, Bisogni, S., additional, Crenshaw, D. M., additional, Denney, K. D., additional, Ely, J., additional, Fausnaugh, M. M., additional, Grier, C. J., additional, Gupta, A., additional, Horne, K. D., additional, Kaastra, J., additional, Pancoast, A., additional, Pei, L., additional, Pogge, R. W., additional, Skielboe, A., additional, Starkey, D., additional, Vestergaard, M., additional, Zu, Y., additional, Anderson, M. D., additional, Arévalo, P., additional, Bazhaw, C., additional, Borman, G. A., additional, Boroson, T. A., additional, Bottorff, M. C., additional, Brandt, W. N., additional, Breeveld, A. A., additional, Brewer, B. J., additional, Cackett, E. M., additional, Carini, M. T., additional, Croxall, K. V., additional, Bontà, E. Dalla, additional, Lorenzo-Cáceres, A. De, additional, Dietrich, M., additional, Efimova, N. V., additional, Evans, P. A., additional, Filippenko, A. V., additional, Flatland, K., additional, Gehrels, N., additional, Geier, S., additional, Gelbord, J. M., additional, Gonzalez, L., additional, Gorjian, V., additional, Grupe, D., additional, Hall, P. B., additional, Hicks, S., additional, Horenstein, D., additional, Hutchison, T., additional, Im, M., additional, Jensen, J. J., additional, Joner, M. D., additional, Jones, J., additional, Kaspi, S., additional, Kelly, B. C., additional, Kennea, J. A., additional, Kim, M., additional, Kim, S. C., additional, Klimanov, S. A., additional, Lee, J. C., additional, Leonard, D. C., additional, Lira, P., additional, MacInnis, F., additional, Manne-Nicholas, E. R., additional, Mathur, S., additional, McHardy, I. M., additional, Montouri, C., additional, Musso, R., additional, Nazarov, S. V., additional, Norris, R. P., additional, Nousek, J. A., additional, Okhmat, D. N., additional, Papadakis, I., additional, Parks, J. R., additional, Pott, J.-U., additional, Rafter, S. E., additional, Rix, H.-W., additional, Saylor, D. A., additional, Schimoia, J. S., additional, Schnülle, K., additional, Sergeev, S. G., additional, Siegel, M., additional, Spencer, M., additional, Sung, H.-I., additional, Teems, K. G., additional, Treu, T., additional, Turner, C. S., additional, Uttley, P., additional, Villforth, C., additional, Weiss, Y., additional, Woo, J.-H., additional, Yan, H., additional, Young, S., additional, and Zheng, W.-K., additional

Published
2016
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43. SPACE TELESCOPE AND OPTICAL REVERBERATION MAPPING PROJECT. III. OPTICAL CONTINUUM EMISSION AND BROADBAND TIME DELAYS IN NGC 5548

Author

Fausnaugh, M. M., primary, Denney, K. D., additional, Barth, A. J., additional, Bentz, M. C., additional, Bottorff, M. C., additional, Carini, M. T., additional, Croxall, K. V., additional, Rosa, G. De, additional, Goad, M. R., additional, Horne, Keith, additional, Joner, M. D., additional, Kaspi, S., additional, Kim, M., additional, Klimanov, S. A., additional, Kochanek, C. S., additional, Leonard, D. C., additional, Netzer, H., additional, Peterson, B. M., additional, Schnülle, K., additional, Sergeev, S. G., additional, Vestergaard, M., additional, Zheng, W.-K., additional, Zu, Y., additional, Anderson, M. D., additional, Arévalo, P., additional, Bazhaw, C., additional, Borman, G. A., additional, Boroson, T. A., additional, Brandt, W. N., additional, Breeveld, A. A., additional, Brewer, B. J., additional, Cackett, E. M., additional, Crenshaw, D. M., additional, Bontà, E. Dalla, additional, Lorenzo-Cáceres, A. De, additional, Dietrich, M., additional, Edelson, R., additional, Efimova, N. V., additional, Ely, J., additional, Evans, P. A., additional, Filippenko, A. V., additional, Flatland, K., additional, Gehrels, N., additional, Geier, S., additional, Gelbord, J. M., additional, Gonzalez, L., additional, Gorjian, V., additional, Grier, C. J., additional, Grupe, D., additional, Hall, P. B., additional, Hicks, S., additional, Horenstein, D., additional, Hutchison, T., additional, Im, M., additional, Jensen, J. J., additional, Jones, J., additional, Kaastra, J., additional, Kelly, B. C., additional, Kennea, J. A., additional, Kim, S. C., additional, Korista, K. T., additional, Kriss, G. A., additional, Lee, J. C., additional, Lira, P., additional, MacInnis, F., additional, Manne-Nicholas, E. R., additional, Mathur, S., additional, McHardy, I. M., additional, Montouri, C., additional, Musso, R., additional, Nazarov, S. V., additional, Norris, R. P., additional, Nousek, J. A., additional, Okhmat, D. N., additional, Pancoast, A., additional, Papadakis, I., additional, Parks, J. R., additional, Pei, L., additional, Pogge, R. W., additional, Pott, J.-U., additional, Rafter, S. E., additional, Rix, H.-W., additional, Saylor, D. A., additional, Schimoia, J. S., additional, Siegel, M., additional, Spencer, M., additional, Starkey, D., additional, Sung, H.-I., additional, Teems, K. G., additional, Treu, T., additional, Turner, C. S., additional, Uttley, P., additional, Villforth, C., additional, Weiss, Y., additional, Woo, J.-H., additional, Yan, H., additional, and Young, S., additional

Published
2016
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44. Multi-Wavelength Observations of the Blazar 1ES 1011+496 in Spring 2008

Author

Ahnen, M. L., primary, Ansoldi, S., additional, Antonelli, L. A., additional, Antoranz, P., additional, Babic, A., additional, Banerjee, B., additional, Bangale, P., additional, de Almeida, U. Barres, additional, Barrio, J. A., additional, González, J. Becerra, additional, Bednarek, W., additional, Bernardini, E., additional, Biasuzzi, B., additional, Biland, A., additional, Blanch, O., additional, Bonnefoy, S., additional, Bonnoli, G., additional, Borracci, F., additional, Bretz, T., additional, Carmona, E., additional, Carosi, A., additional, Chatterjee, A., additional, Clavero, R., additional, Colin, P., additional, Colombo, E., additional, Contreras, J. L., additional, Cortina, J., additional, Covino, S., additional, Da Vela, P., additional, Dazzi, F., additional, De Angelis, A., additional, De Caneva, G., additional, De Lotto, B., additional, Wilhelmi, E. de O na, additional, Mendez, C. Delgado, additional, Pierro, F. Di, additional, Prester, D. Dominis, additional, Dorner, D., additional, Doro, M., additional, Einecke, S., additional, Elsaesser, D., additional, Fernández-Barral, A., additional, Fidalgo, D., additional, Fonseca, M. V., additional, Font, L., additional, Frantzen, K., additional, Fruck, C., additional, Galindo, D., additional, López, R. J. García, additional, Garczarczyk, M., additional, Terrats, D. Garrido, additional, Gaug, M., additional, Giammaria, P., additional, Glawion(Eisenacher), D., additional, Godinović, N., additional, Muñoz, A. González, additional, Guberman, D., additional, Hanabata, Y., additional, Hayashida, M., additional, Herrera, J., additional, Hose, J., additional, Hrupec, D., additional, Hughes, G., additional, Idec, W., additional, Kodani, K., additional, Konno, Y., additional, Kubo, H., additional, Kushida, J., additional, La Barbera, A., additional, Lelas, D., additional, Lindfors, E., additional, Lombardi, S., additional, Longo, F., additional, López, M., additional, López-Coto, R., additional, López-Oramas, A., additional, Lorenz, E., additional, Majumdar, P., additional, Makariev, M., additional, Mallot, K., additional, Maneva, G., additional, Manganaro, M., additional, Mannheim, K., additional, Maraschi, L., additional, Marcote, B., additional, Mariotti, M., additional, Martínez, M., additional, Mazin, D., additional, Menzel, U., additional, Miranda, J. M., additional, Mirzoyan, R., additional, Moralejo, A., additional, Nakajima, D., additional, Neustroev, V., additional, Niedzwiecki, A., additional, Rosillo, M. Nievas, additional, Nilsson, K., additional, Nishijima, K., additional, Noda, K., additional, Orito, R., additional, Overkemping, A., additional, Paiano, S., additional, Palacio, J., additional, Palatiello, M., additional, Paneque, D., additional, Paoletti, R., additional, Paredes, J. M., additional, Paredes-Fortuny, X., additional, Persic, M., additional, Poutanen, J., additional, Moroni, P. G. Prada, additional, Prandini, E., additional, Puljak, I., additional, Reinthal, R., additional, Rhode, W., additional, Ribó, M., additional, Rico, J., additional, Garcia, J. Rodriguez, additional, Rügamer, S., additional, Saito, T., additional, Satalecka, K., additional, Scapin, V., additional, Schultz, C., additional, Schweizer, T., additional, Shore, S. N., additional, Sillanpää, A., additional, Sitarek, J., additional, Snidaric, I., additional, Sobczynska, D., additional, Stamerra, A., additional, Steinbring, T., additional, Strzys, M., additional, Takalo, L., additional, Takami, H., additional, Tavecchio, F., additional, Temnikov, P., additional, Terzić, T., additional, Tescaro, D., additional, Teshima, M., additional, Thaele, J., additional, Torres, D. F., additional, Toyama, T., additional, Treves, A., additional, Verguilov, V., additional, Vovk, I., additional, Ward, J. E., additional, Will, M., additional, Wu, M. H., additional, Zanin, R., additional, Lucarelli, F., additional, Pittori, C., additional, Vercellone, S., additional, Berdyugin, A., additional, Carini, M. T., additional, Lähteenmäki, A., additional, Pasanen, M., additional, Pease, A., additional, Sainio, J., additional, Tornikoski, M., additional, and Walters, R., additional

Published
2016
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45. Results from the Blazar Monitoring Campaign at the Whipple 10m Gamma-ray Telescope

Author

Steele, David, Collaboration, For The VERITAS, Carini, M. T., Charlot, P., Kurtanidze, O., Lahteenmaki, A., Montaruli, T., Sadun, A. C., Villata, M., Institute of Space and Atmospheric Studies [Saskatoon] (ISAS), Department of Physics and Engineering Physics [Saskatoon], University of Saskatchewan [Saskatoon] (U of S)-University of Saskatchewan [Saskatoon] (U of S), Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire aquitain des sciences de l'univers (OASU), Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astrofisico di Torino (OATo), and Istituto Nazionale di Astrofisica (INAF)

Subjects
[PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Astrophysics (astro-ph), [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], FOS: Physical sciences, Astrophysics
Abstract

In September 2005, the observing program of the Whipple 10 m gamma-ray telescope was redefined to be dedicated almost exclusively to AGN monitoring. Since then the five Northern Hemisphere blazars that had already been detected at Whipple are monitored routinely each night that they are visible. Thanks to the efforts of a large number of multiwavelength collaborators, the first year of this program has been very successful. We report here on the analysis of Markarian 421 observations taken from November, 2005 to May, 2006 in the gamma-ray, X-ray, optical and radio bands., 4 pages; contribution to the 30th International Cosmic Ray Conference, Merida, Mexico, July 2007

Published
2008

47. Large-scale wind structures in OB supergiants: a search for rotationally modulated H��variability

Author

Morel, T., Marchenko, S. V., Pati, A. K., Kuppuswamy, K., Carini, M. T., Wood, E., and Zimmerman, R.

Subjects
Astrophysics (astro-ph), FOS: Physical sciences
Abstract

We present the results of a long-term monitoring campaign of the H��line in a sample of bright OB-supergiants (O7.5-B9) that aims at detecting rotationally modulated changes potentially related to the existence of large-scale wind structures. A total of 22 objects were monitor ed during 36 nights spread over 6 months in 2001-2002. Coordinated broad-band photometric observations were also obtained for some targets. Conspicuous evidence for variability in H��is found for the stars displaying a feature contaminated by wind emission. Most changes take place on a daily time-scale, although hourly variations are also occasionally detected. Convincing evidence for a cyclical pattern of variability in H��has been found in 2 stars: HD 14134 and HD 42087 (periodic signals are also detected in other stars, but independent confirmation is required). Rotational modulation is suggested from the similarity between the observed recurrence time-scales (in the range 13-25 days) and estimated periods of stellar rotation. We call attention to the atypical case of HD 14134 which exhibits a clear 12.8-d periodicity both in the photometric and in the spectroscopic data sets. This places this object among a handful of early-type stars where one may observe a clear link between extended wind structures and photospheric disturbances. Further modelling may test the hypothesis that azimuthally-extended wind streams are responsible for the patterns of spectral variability in our target stars., 18 pages, accepted for publication in MNRAS

Published
2004
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