A5073350418- Astrophysics and Cosmic Phenomena
- Galaxies: Formation, Evolution, Phenomena
- Radio Astronomy Observations and Technology
- Astrophysical Phenomena and Observations
- Cosmology and Gravitation Theories
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Pulsars and Gravitational Waves Research
Princeton University
2024
California Institute of Technology
2021-2024
Abstract Most large galaxies host supermassive black holes in their nuclei and are subject to mergers, which can produce a hole binary (SMBHB), hence periodic signatures due orbital motion. We report unique radio flux density variations the blazar PKS 2131−021, strongly suggest an SMBHB with separation of ∼0.001–0.01 pc. Our 45.1 yr light curve shows two epochs strong sinusoidal variation same period phase within ≲2% ∼10%, respectively, straddling 20 when this was absent. simulated curves...
Abstract We use a sample of 54 compact symmetric objects (CSOs) to confirm that there are two unrelated CSO classes: an edge-dimmed, low-luminosity class (CSO 1), and edge-brightened, high-luminosity 2). Using blind tests, we show 2s consist three subclasses: 2.0, having prominent hot spots at the leading edges narrow jets and/or lobes; 2.2, without with broad 2.1, which exhibit mixed properties. Most do not evolve into larger jetted active galactic nuclei (AGN), but spend their whole life...
Abstract Compact symmetric objects (CSOs) are compact (<1 kpc), jetted active galactic nuclei (AGN), whose jet axes not aligned close to the line of sight, and observed emission is predominantly relativistically boosted toward us. Two classes CSOs have previously been identified: approximately one-fifth edge dimmed rest brightened. We designate these as CSO 1s 2s, respectively. This paper focuses almost exclusively on 2s. Using complete samples 2s we present three independent lines...
Abstract Haystack and Owens Valley Radio Observatory observations recently revealed strong, intermittent, sinusoidal total flux-density variations that maintained their coherence between 1975 2021 in the blazar PKS 2131−021 ( z = 1.283). This was interpreted as possible evidence of a supermassive black hole binary (SMBHB). Extended through 2023 show over 47.9 yr, with an observed period P 15 GHz (1739.8 ± 17.4) days. We reject, p -value 2.09 × 10 −7 , hypothesis are due to random...
Abstract Symmetric achromatic variability (SAV) is a rare form of radio in blazars that has been attributed to gravitational milli-lensing by ∼10 2 –10 5 M ⊙ mass condensate. Four SAVs have identified between 1980 and 2020 the long-term monitoring data blazar PKS 1413 + 135. We show all four can be fitted with same, unchanging, lens model. If SAV due milli-lensing, 135 provides unique system for studying active galactic nuclei unprecedented microarcsecond resolution, as well nature...
Compact Symmetric Objects (CSOs), young jetted-AGN of overall projected size <1 kpc, are great interest due to their youth and evolution. The classification was introduced distinguish between ~95% powerful compact extragalactic radio sources in flux density limited samples that dominated by asymmetric emission relativistic beaming from jets aligned close the line sight, ~5% objects not. original criteria were: (i) diameter smaller than ~1 (ii) identified center activity, (iii) symmetric jet...
Abstract This paper addresses, for the first time, a key aspect of phenomenology compact symmetric objects (CSOs): characteristics their radio spectra. We present radio-spectrum description complete sample high-luminosity CSOs (CSO-2s), which shows that they exhibit range spectral types, including flat-spectrum sources ( α ≥ −0.5), steep-spectrum < and peaked-spectrum sources. show there is no clear correlation between type size, but high-frequency index both object size. also that, to...