X-Ray and Optical Correlation of Type I Seyfert NGC 3516 Studied With Suzaku and Japanese Ground-Based Telescopes

Noda, Hirofumi; Minezaki, Takeo; Watanabe, Makoto; Kokubo, Mitsuru; Kawaguchi, Kotaro; Itoh, R.; Morihana, K.; Saito, Yoshihiko; Nakao, Hikaru; Imaï, Masataka; Moritani, Yuki; Takaki, K.; Kawabata, Miho; Nakaoka, Tatsuya; Uemura, Makoto; Yoshida, Michitoshi; Arai, Akira; Takagi, Y.; Morokuma, Tomoki; Doi, Mamoru; Itoh, Yoichi; Yamada, S.; Nakazawa, K.; Fukazawa, Yasushi; Makishima, Kazuo

doi:10.3847/0004-637x/828/2/78

Cited by 47 publications

(59 citation statements)

References 112 publications

(172 reference statements)

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“…This is not unusual for Seyfert galaxies, as discussed by Edelson et al (2000). Recently, Noda et al (2016) found from a simultaneous X-ray and optical monitoring program during the faintest phase of NGC 3516 (2013of NGC 3516 ( -2014 that the X-ray flux and B-band variations were comparable and significantly correlated, with the B-band delayed by ∼2 days relative to the X-rays. Both results indicate that the standard X-ray reprocessing model in which the X-ray source heats a stratified accretion disk, which then reemits in the optical and ultraviolet, may not be applicable in the case of NGC 3516 and that these two emitting regions are powered primarily by different processes (Edelson et al 2000;Noda et al 2016).…”

Section: Introductionmentioning

confidence: 71%

“…NGC 3516 shows even more interesting properties in the high-energy band (e.g., Edelson et al 2000;Netzer et al 2002;Maoz et al 2002;Turner et al 2005;Mehdipour et al 2010;Liu et al 2014;Huerta et al 2014;Noda et al 2016). Edelson et al (2000) showed that there are uncorrelated trends on longer timescales between the X-ray and optical bands, which was supported with the later findings of Maoz et al (2002).…”

Section: Introductionmentioning

confidence: 74%

“…It is a face-on spiral galaxy at a distance of between Article number, page 1 of 7 arXiv:2004.01308v2 [astro-ph.GA] 9 Apr 2020 D ≈38 Mpc and 66 Mpc 1 . NGC 3516 has previously been the subject of several optical monitoring campaigns (e.g., Lyutyi & Doroshenko 1993;Wanders et al 1993;Wanders & Horne 1994;Maoz et al 2002;Noda et al 2016;De Rosa et al 2018;Shapovalova et al 2019, etc. ), which showed that the object is variable on short and long timescales.…”

Section: Introductionmentioning

confidence: 99%

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A flare in the optical spotted in the changing-look Seyfert NGC 3516

Ilić

Tsygankov

Belinski

et al. 2020

A&A

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Context. We present observations from the short-term intensive optical campaign (from September 2019 to January 2020) of the changing-look Seyfert NGC 3516. This active galactic nucleus is known to have strong optical variability and has changed its type in the past. It has been in the low-activity state in the optical since 2013, with some rebrightening from the end of 2015 to the beginning of 2016, after which it remained dormant. Aims. We aim to study the photometric and spectral variability of NGC 3516 from the new observations in U-and B-bands and examine the profiles of the optical broad emission lines in order to demonstrate that this object may be entering a new state of activity. Methods. NGC 3516 has been monitored intensively for the past 4 months with an automated telescope in U and B filters, enabling accurate photometry of 0.01 precision. Spectral observations were triggered when an increase in brightness was spotted. We support our analysis of past-episodes of violent variability with the UV and X-ray long-term light curves constructed from the archival Swift/UVOT and Swift/XRT data.Results. An increase of the photometric magnitude is seen in both U and B filters to a maximum amplitude of 0.25 mag and 0.11 mag, respectively. During the flare, we observe stronger forbidden high-ionization iron lines ([Fe vii] and [Fe x]) than reported before, as well as the complex broad Hα and Hβ lines. This is especially seen in Hα, which appears to be double-peaked. It seems that a very broad component of ∼10,000 km s −1 in width in the Balmer lines is appearing. The trends in the optical, UV, and X-ray light curves are similar, with the amplitudes of variability being significantly larger in the case of UV and X-ray bands. Conclusions. The increase of the continuum emission, the variability of the coronal lines, and the very broad component in the Balmer lines may indicate that the AGN of NGC 3516 is finally leaving the low-activity state in which it has been for the last ∼3 years.

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Section: Introductionmentioning

confidence: 71%

Section: Introductionmentioning

confidence: 74%

Section: Introductionmentioning

confidence: 99%

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A flare in the optical spotted in the changing-look Seyfert NGC 3516

Ilić

Tsygankov

Belinski

et al. 2020

A&A

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“…In addition to the AGN STORM campaign, a series of studies on other AGN have come to similar conclusions -e.g. NGC 2617 (Shappee et al 2014), NGC 6814 (Troyer et al 2016), NGC 3516 (Noda et al 2016) and Fairall 9 (Pal et al 2017). In addition, Buisson et al (2017) analyzed a sample of 21 AGN with Swift and find that the UV lags generally appear to be longer than expected for a thin disc (also see Jiang et al 2017).…”

Section: Bandsmentioning

confidence: 99%

X-ray, UV, and optical time delays in the bright Seyfert galaxy Ark 120 with co-ordinated Swift and ground-based observations

Lobban

Zoła

Pajdosz-Śmierciak

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We report on the results of a multiwavelength monitoring campaign of the bright, nearby Seyfert galaxy, Ark 120 using a ∼50-day observing programme with Swift and a ∼4-month co-ordinated ground-based observing campaign, predominantly using the Skynet Robotic Telescope Network. We find Ark 120 to be variable at all optical, UV, and X-ray wavelengths, with the variability observed to be well-correlated between wavelength bands on short timescales. We perform cross-correlation analysis across all available wavelength bands, detecting time delays between emission in the X-ray band and the Swift V, B and UVW1 bands. In each case, we find that the longer-wavelength emission is delayed with respect to the shorterwavelength emission. Within our measurement uncertainties, the time delays are consistent with the τ ∼ λ 4/3 relation, as predicted by a disc reprocessing scenario. The measured lag centroids are τ cent = 11.90 ± 7.33, 10.80 ± 4.08, and 10.60 ± 2.87 days between the X-ray and V, B, and UVW1 bands, respectively. These time delays are longer than those expected from standard accretion theory and, as such, Ark 120 may be another example of an active galaxy whose accretion disc appears to exist on a larger scale than predicted by the standard thin-disc model. Additionally, we detect further inter-band time delays: most notably between the ground-based I and B bands (τ cent = 3.46 ± 0.86 days), and between both the Swift XRT and UVW1 bands and the I band (τ cent = 12.34 ± 4.83 and 2.69 ± 2.05 days, respectively), highlighting the importance of co-ordinated ground-based optical observations.

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“…This is the equivalent to the disks being too big (the lag too large) by a factor of 1.6 based on the observed flux compared to the accretion disk model. More recently, observations of NGC2617 (Shappee et al 2014), NGC3516 (Noda et al 2016), NGC6814 (Troyer et al 2016), Fairall9 (Pal et al 2017), Ark120 (Gliozzi et al 2017), and a sample of 21 AGNs in the Swift archive (Buisson et al 2017) all find lags that are longer than expected for a standard thin disk. Both Pan-STARRS and the Dark Energy Survey (DES) are obtaining light curves of quasars in multiple photometric bands, allowing for determination of the average sizes from a large number of objects (Jiang et al 2017;Mudd et al 2017).…”

Section: Introductionmentioning

confidence: 97%

Accretion Disk Reverberation with Hubble Space Telescope Observations of NGC 4593: Evidence for Diffuse Continuum Lags

Cackett

Chiang

McHardy

et al. 2018

ApJ

132

186

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The Seyfert 1 galaxy NGC 4593 was monitored spectroscopically with the Hubble Space Telescope as part of a reverberation mapping campaign that also included Swift, Kepler, and ground-based photometric monitoring. During 2016 July 12-August 6, we obtained 26 spectra across a nearly continuous wavelength range of ∼1150-10000 Å. These were combined with Swift data to produce a UV/optical "lag spectrum," which shows the interband lag relative to the Swift UVW2 band as a function of wavelength. The broad shape of the lag spectrum appears to follow the τ ∝ λ 4/3 relation seen previously in photometric interband lag measurements of other active galactic nuclei (AGNs). This shape is consistent with the standard thin disk model, but the magnitude of the lags implies a disk that is a factor of ∼3 larger than predicted, again consistent with what has been previously seen in other AGNs. In all cases these large disk sizes, which are also implied by independent gravitational microlensing of higher-mass AGNs, cannot be simply reconciled with the standard model. However, the most striking feature in this higher-resolution lag spectrum is a clear excess around the 3646 Å Balmer jump. This strongly suggests that diffuse emission from gas in the much larger broad-line region (BLR) must also contribute significantly to the interband lags. While the relative contributions of the disk and BLR cannot be uniquely determined in these initial measurements, it is clear that both will need to be considered to comprehensively model and understand AGN lag spectra.

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X-Ray and Optical Correlation of Type I Seyfert NGC 3516 Studied With Suzaku and Japanese Ground-Based Telescopes

Cited by 47 publications

References 112 publications

A flare in the optical spotted in the changing-look Seyfert NGC 3516

A flare in the optical spotted in the changing-look Seyfert NGC 3516

X-ray, UV, and optical time delays in the bright Seyfert galaxy Ark 120 with co-ordinated Swift and ground-based observations

Accretion Disk Reverberation with Hubble Space Telescope Observations of NGC 4593: Evidence for Diffuse Continuum Lags

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