Hard X-Ray broadband spectroscopy of Mrk 876: characterizing its spectrum

Bottacini, E.

doi:10.1093/mnras/stac1890

Cited by 4 publications

(5 citation statements)

References 69 publications

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“…This fit fails for a * = 0, with the corona height H becoming nonphysical. This agrees with previous investigations indicating that Mrk 876's SMBH has a high spin parameter (Bottacini 2022). We also perform the fitting allowing m E  to be a free parameter.…”

Section: Theoretical Time Lagssupporting

confidence: 89%

Continuum Reverberation Mapping of Mrk 876 over Three Years with Remote Robotic Observatories

Miller

Cackett

Goad

et al. 2023

ApJ

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Continuum reverberation mapping probes the size scale of the optical continuum-emitting region in active galactic nuclei (AGN). Through 3 yr of multiwavelength photometric monitoring in the optical with robotic observatories, we perform continuum reverberation mapping on Mrk 876. All wave bands show large-amplitude variability and are well correlated. Slow variations in the light curves broaden the cross-correlation function (CCF) significantly, requiring detrending in order to robustly recover interband lags. We measure consistent interband lags using three techniques (CCF, JAVELIN, and PyROA), with a lag of around 13 days from u to z. These lags are longer than the expected radius of 12 days for the self-gravitating radius of the disk. The lags increase with wavelength roughly following λ 4/3, as would be expected from thin disk theory, but the lag normalization is approximately a factor of 3 longer than expected, as has also been observed in other AGN. The lag in the i band shows an excess that we attribute to variable Hα broad-line emission. A flux–flux analysis shows a variable spectrum that follows f ν ∝ λ −1/3, as expected for a disk, and an excess in the i band that also points to strong variable Hα emission in that band.

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Section: Theoretical Time Lagssupporting

confidence: 89%

Continuum Reverberation Mapping of Mrk 876 over Three Years with Remote Robotic Observatories

Miller

Cackett

Goad

et al. 2023

ApJ

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“…First, MRK 876 shows strong variability (40%) on time scales of months (see Fig. 8 of Bottacini 2022). Second, we have merged the 12 Chandra observations and find no structure beyond one single source (14949 counts with 10 background in the energy band 0.6-3.0 keV).…”

Section: 'mentioning

confidence: 72%

A Swift X-Ray View of the SMS4 Sample—X-Ray Properties of 31 Quasars and Radio Galaxies

Maselli¹,

Forman²,

Jones³

et al. 2022

ApJS

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We present Neil Gehrels Swift Observatory (hereafter Swift) observations of 31 sources from the SMS4 catalog, a sample of 137 bright radio sources originally designed to extend the well-studied 3CRR radio sample to the Southern Hemisphere. All these sources had no Chandra or XMM-Newton observations: 24 of these were observed with Swift through a dedicated proposal in 2015, and data for the remaining seven were retrieved from the Swift archive. The reduction and analysis of data collected by the Swift X-ray Telescope (XRT) led to 20 detections in the 0.3–10 keV band. We provide details of the X-ray emission in this band for these 20 detections, as well as upper limits for the remaining 11 SMS4 sources. When statistics allowed, we investigated the extent of the X-ray emission and the hardness ratio, and we carried out a spectral analysis. We matched the 20 X-ray-detected sources with infrared (AllWISE, CatWISE2020) and optical (GSC 2.3.2, DES DR2) catalogs to establish associations with infrared and optical sources and compared our results with previously published counterparts in these bands. Requiring a detection in both the infrared and optical bands to establish a candidate counterpart for our X-ray detections, we obtain reliable counterparts for 18 sources, while the remaining two sources need further investigation to establish firm identifications. In the infrared, we confirm 12 previously established counterparts and provide six new candidates. In the optical, we find agreement with 13 previously established counterparts, while we provide an alternative candidate for five SMS4 sources. We find that ∼35% of all the SMS4 sources lie below the lower limit of 10.9 Jy for the flux density at 178 MHz established for the 3CRR sample, at variance with the values extrapolated using measurements at higher frequencies. Therefore, for future studies where flux-density-limited samples are needed, we encourage the use of the more recent G4Jy sample. We present the list of 56 SMS4 sources that in 2022 March remain to be observed in the X-rays with narrow-field instruments, to highlight interesting sources and organize further observational campaigns to achieve complete X-ray coverage for the whole SMS4 in the forthcoming years.

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“…However, a model in which the cyclotron line was replaced with a Gaussian emission line or a Compton hump led to a poorer-quality fit. As an additional test, we followed the procedure in Bottacini (2022) where the cyclotron energy was stepped in increments of 0.4 keV (NuSTAR's energy resolution) through the full 3-79 keV band, until the best fit was obtained based on χ 2 . Once again, the cyclotron was detected significantly around 14 keV (according to the reduced F-statistic distribution) and away from the cutoff energy and the possible bump.…”

Section: Discussionmentioning

confidence: 99%

Drop in the Hard Pulsed Fraction and a Candidate Cyclotron Line in IGR J16320–4751 Seen by NuSTAR

Bodaghee¹,

Chiu

Tomsick

et al. 2023

ApJ

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We report on a timing and spectral analysis of a 50 ks NuSTAR observation of IGR J16320−4751 (= AX J1631.9−4752), a high-mass X-ray binary hosting a slowly rotating neutron star. In this observation from 2015, the spin period was 1308.8 ± 0.4 s giving a period derivative P ̇ ∼ 2 × 10 − 8 s s−1 when compared with the period measured in 2004. In addition, the pulsed fraction decreased as a function of energy, as opposed to the constant trend that was seen previously. This suggests a change in the accretion geometry of the system during the intervening 11 yr. The phase-averaged spectra were fit with the typical model for accreting pulsars: a power law with an exponential cutoff. This left positive residuals at 6.4 keV attributable to the known iron Kα line, as well as negative residuals around 14 keV from a candidate cyclotron line detected at a significance of 5σ. We found no significant differences in the spectral parameters across the spin period, other than the expected changes in flux and component normalizations. A flare lasting around 5 ks was captured during the first half of the observation, where the X-ray emission hardened and the local column density decreased. Finally, the binary orbital period was refined to 8.9912 ± 0.0078 days thanks to Swift/BAT monitoring data from 2005–2022.

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Hard X-Ray broadband spectroscopy of Mrk 876: characterizing its spectrum

Cited by 4 publications

References 69 publications

Continuum Reverberation Mapping of Mrk 876 over Three Years with Remote Robotic Observatories

Continuum Reverberation Mapping of Mrk 876 over Three Years with Remote Robotic Observatories

A Swift X-Ray View of the SMS4 Sample—X-Ray Properties of 31 Quasars and Radio Galaxies

Drop in the Hard Pulsed Fraction and a Candidate Cyclotron Line in IGR J16320–4751 Seen by NuSTAR

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