Impact of Baseline, Cadence, and Host Contamination on AGN Variability Metrics: A Systematic Study with ZTF
Diego Martínez Collipal, Swayamtrupta Panda
TLDR
This study systematically evaluates AGN variability metrics "J" and "s" against baseline, cadence, and host contamination, finding J more robust.
Key contributions
- Evaluated Stetson index "J" and smoothness "s" for AGN variability using ZTF data.
- Both "J" and "s" are robust to ~2 years of baseline variations.
- "J" is robust to cadence and host contamination, while "s" is highly sensitive.
- "s" varies >40% with cadence, whereas "J" varies <10%.
Why it matters
Characterizing AGN variability is key to understanding supermassive black hole accretion physics. This study provides critical guidance on the reliability of common variability metrics, ensuring more accurate interpretations of observational data. It helps researchers choose robust tools for future AGN studies.
Original Abstract
Variability in active galactic nuclei (AGN) probes the physics of accretion onto supermassive black holes. This variability is characterized using metrics derived from the flux distributions of temporally separated epochs. We studied the stability of two variability metrics, the Stetson index "J" and the smoothness "s", against baseline, cadence, and host galaxy contamination. We studied 23 nearby AGNs using Zwicky Transient Facility's Data Release 24. Both metrics are robust to baseline variations of $\sim 2$ years. However, s is sensitive to cadence, showing variations $\gtrsim 40\%$, while J shows minor variations $\lesssim10\%$. We studied the host galaxy impact using Mrk 493 as a representative case. We found that J remains unchanged after host subtraction, while s increases. We concluded that J is a robust tool for characterizing AGN variability, while s should be interpreted with caution.
📬 Weekly AI Paper Digest
Get the top 10 AI/ML arXiv papers from the week — summarized, scored, and delivered to your inbox every Monday.