arXiv subjects

Dragana Ilić

Publications and source records attributed to Dragana Ilić.

23 records · Page 2Linked to original sources

arXiv2021

The broad emission line asymmetry in low mass ratio of supermassive binary black holes on elliptical orbits

We investigate the broad line profiles emitted from a system supermassive binary black hole (SMBBH) having elliptical orbits and low mass ratio of $m_2/m_1\sim 0.1$. Our model assumes a super Eddington accretion flow in the case of a smaller component, whereas the massive component has very small or negligible accretion, therefore supposing that no broad line region (BLR) is attached to it. Thus, the proposed SMBBH system contains one moving BLR, associated with the less massive component and one circum-binary BLR. We study the effect of different total mass of the system (ranging from 10$^6$ to 10$^8$ Solar masses) to the $\mathrm{Hβ}$ line profiles and to the continuum and line light curves. The resulted broad line profiles are asymmetric and shifted, and are varying during the orbital period. The asymmetry in the broad line profiles is discussed in terms of expected differences between the proposed model of the SMBBH with one active component and the scenario of a recoiling black hole. We discuss the periodicity detected in the line and continuum light curves, as well as in the variations of the line asymmetry and shift.

astro-ph.GA↗

arXiv2021

Detecting subparsec super-massive binary black holes: Long termmonitoring perspective

Here we consider the perspective to detect sub-pc super-massive binary black-hole (SMBBH) systems using long-term photometric and spectroscopic monitoring campaigns of active galactic nuclei. This work explores the nature of long-term spectral variability caused by the dynamical effects of SMBBH systems. We describe in great detail a model of SMBBH system which considers that both black holes have their accretion disc and additional line emitting region(s). We simulate the H$β$ spectral band (continuum+broad H$β$ line) for different mass ratios of components and different total masses of the SMBBH systems ($10^6-10^8\mathrm{M\odot}$). We analyze the set of continuum and broad line light curves for several full orbits of SMBBHs with different parameters, to test the possibility to extract the periodicity of the system. We consider different levels of the signal-to-noise ratio, which is added to the simulated spectra. Our analysis showed that the continuum and broad line profiles emitted from an SMBBH system are strongly dependent, not only on the mass ratio of the components but also on the total mass of the system. We found that the mean broad line profile and its rms could indicate the presence of an SMBBH. However, some effects caused by the dynamics of a binary system could be hidden due to a low signal-to-noise ratio. Finally, we can conclude that the long-term AGN monitoring campaigns could be beneficial for the detection of SMBBH candidates.

astro-ph.HE↗

arXiv2020

Variability and the size-luminosity relation of the intermediate mass AGN in NGC 4395

We present the variability study of the lowest-luminosity Seyfert 1 galaxy NGC 4395 based on the photometric monitoring campaigns in 2017 and 2018. Using 22 ground-based and space telescopes, we monitored NGC 4395 with a $\sim$5 minute cadence during a period of 10 days and obtained light curves in the UV, V, J, H, and K/Ks bands as well as the H$α$ narrow-band. The RMS variability is $\sim$0.13 mag on \emph{Swift}-UVM2 and V filter light curves, decreasing down to $\sim$0.01 mag on K filter. After correcting for continuum contribution to the H$α$ narrow-band, we measured the time lag of the H$α$ emission line with respect to the V-band continuum as ${55}^{+27}_{-31}$ to ${122}^{+33}_{-67}$ min. in 2017 and ${49}^{+15}_{-14}$ to ${83}^{+13}_{-14}$ min. in 2018, depending on the assumption on the continuum variability amplitude in the H$α$ narrow-band. We obtained no reliable measurements for the continuum-to-continuum lag between UV and V bands and among near-IR bands, due to the large flux uncertainty of UV observations and the limited time baseline. We determined the AGN monochromatic luminosity at 5100Å $λL_λ= \left(5.75\pm0.40\right)\times 10^{39}\,\mathrm{erg\,s^{-1}}$, after subtracting the contribution of the nuclear star cluster. While the optical luminosity of NGC 4395 is two orders of magnitude lower than that of other reverberation-mapped AGNs, NGC 4395 follows the size-luminosity relation, albeit with an offset of 0.48 dex ($\geq$2.5$σ$) from the previous best-fit relation of Bentz et al. (2013).

astro-ph.GA↗

arXiv2019

The Detailed Science Case for the Maunakea Spectroscopic Explorer, 2019 edition

(Abridged) The Maunakea Spectroscopic Explorer (MSE) is an end-to-end science platform for the design, execution and scientific exploitation of spectroscopic surveys. It will unveil the composition and dynamics of the faint Universe and impact nearly every field of astrophysics across all spatial scales, from individual stars to the largest scale structures in the Universe. Major pillars in the science program for MSE include (i) the ultimate Gaia follow-up facility for understanding the chemistry and dynamics of the distant Milky Way, including the outer disk and faint stellar halo at high spectral resolution (ii) galaxy formation and evolution at cosmic noon, via the type of revolutionary surveys that have occurred in the nearby Universe, but now conducted at the peak of the star formation history of the Universe (iii) derivation of the mass of the neutrino and insights into inflationary physics through a cosmological redshift survey that probes a large volume of the Universe with a high galaxy density. MSE is positioned to become a critical hub in the emerging international network of front-line astronomical facilities, with scientific capabilities that naturally complement and extend the scientific power of Gaia, the Large Synoptic Survey Telescope, the Square Kilometer Array, Euclid, WFIRST, the 30m telescopes and many more.

astro-ph.IM↗

arXiv2018

The intrinsic Baldwin effect in NLSy 1 galaxies

The intrinsic Baldwin effect is an anti-correlation between the line equivalent width and the flux of the underlying continuum detected in a single variable active galactic nucleus (AGN). This effect, in spite of the extensive research, is still not well understood, and might give us more information about the physical properties of the line and continuum emission regions in AGNs. Here we present preliminary results of our investigation of the intrinsic Baldwin effect of the broad H$β$ line in several Narrow-line Seyfert 1 (NLSy 1) galaxies, for which data were taken from the long-term monitoring campaigns and from the Sloan Digital Sky Survey Reverberation Mapping project.

astro-ph.GA↗