Circular Mystery: Exploring Diffuse Emission Surrounding a Radio Galaxy with uGMRT and VLA Multiwavelength Observations

Sabyasachi Pal; Shobha Kumari; Souvik Manik

REVIEW 2 major objections 4 minor 109 references

Circular Mystery: Exploring Diffuse Emission Surrounding a Radio Galaxy with uGMRT and VLA Multiwavelength Observations

T0 review · 2 major / 4 minor · reviewed 2026-08-06 · deepseek-v4-flash

Challenge this review Re-run · record.json Download PDF Read on arXiv ↗

Pith's one-line read J1218+1813 is a genuine ~180 kpc circular radio source around an elliptical galaxy, with a spectrum that steepens from core to edge.

desk verdict A genuine new circular radio source with real multiwavelength data, but the spectral index gradient that headlines the abstract rests on a map whose input images the paper itself says miss the extended emission. read the letter →

arxiv 2506.18556 v1 pith:7KCGGMJX submitted 2025-06-23 astro-ph.GA

Shobha Kumari , Sabyasachi Pal , Souvik Manik This is my paper · ORCID

classification astro-ph.GA

keywords ActivegalacticnucleiRadiosourcesgalaxiesastronomycontinuumemissionOddcirclesDiffuseSpectralindex

verification ladder T0 review T1 audit T2 compute T3 formal

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

The paper reports the discovery of J1218+1813, a circular diffuse radio source with an angular diameter of about one arcminute (roughly 180 kpc at its redshift) that is centered on an elliptical galaxy at z = 0.139635. Using new uGMRT and VLA observations between 402 MHz and 10 GHz, the authors find that the core has a steep spectral index of 0.8, and that the spectrum steepens radially from about 1.1 in the inner structure to about 1.8 at the periphery, the signature of aged synchrotron plasma. They also measure the host galaxy's stellar mass, age, black hole mass, and emission-line classification, and they argue that star formation is not powering the emission. The study aims to establish J1218+1813 as a genuine member of the rare class of circular diffuse radio structures around galaxies and to constrain how such rings form, considering jet precession, a giant blast wave, or restarted AGN activity. A sympathetic reader would care because this source sits at the boundary between known radio galaxies and the newly identified odd radio circles, offering a nearby target for testing formation models.

What carries the argument

The central object is J1218+1813 itself, a ~70-arcsecond circular shell of diffuse synchrotron emission around an elliptical galaxy. The argument is carried by three tools: (1) a spectral index map built with the Broadband Radio Astronomy Tools software from 1274 MHz (uGMRT band 5), 6000 MHz (VLA C band), and 10,000 MHz (VLA X band) images convolved to a common $8.8'' \times 2.92''$ beam with a $3\sigma$ clipping threshold, which reveals the radial steepening; (2) a broken-power-law fit to ten flux-density measurements from 147 MHz to 10 GHz that yields the break frequency and core spectral index; and (3) optical spectroscopy and SED modeling that give the stellar velocity dispersion, stellar mass, age, black hole mass via the $M_{\rm BH}$–$\sigma_*$ relation, and the LINER/HERG classification. The polarization analysis uses NVSS Stokes Q and U images to estimate fractional polarization.

What would settle it

Re-image archival or new deep data with matched short-spacing coverage and make a spectral index map between 1274 and 6000 MHz at the full recovered resolution: if the outer ring is not detected at all three frequencies above $3\sigma$, or if its spectral index is not steeper than the inner structure, the claimed steepening to $\alpha \sim 1.8$ is falsified. A spectroscopic redshift of the ring's edge or an independent measurement of the source's extent would also test whether the radio emission is physically connected to the central galaxy or a chance superposition.

Watch

Extended reading notes

Core claim

J1218+1813 is a circular, diffuse, low-surface-brightness radio source discovered in the VLA FIRST survey at 1400 MHz, with a largest angular size of 70 arcseconds and a physical extent of about 180 kpc at the spectroscopic redshift z = 0.139635 of its optical host, the elliptical galaxy SDSS J121804.88+181353.7. The integrated radio spectrum between 147 MHz and 10 GHz is fitted by a broken power law with a break frequency near 1.56 GHz, and the resolved core has a spectral index $0.80 \pm 0.07$, implying optically thin synchrotron emission. A spectral index map made from observations at 1274 MHz, 6000 MHz, and 10,000 MHz shows the spectrum steepening from $\alpha \sim 1.1$ in the inner structure to $\alpha \sim 1.6$–1.85 around the circular periphery, which the authors interpret as radiative aging of plasma from past AGN activity. The host is a LINER with an excitation index of 2.62 (formally a high-excitation radio galaxy), a black hole mass of $(2.8 \pm 0.8) \times 10^8 M_\odot$, a stellar mass of about $2.9 \times 10^{11} M_\odot$, and an age of 8.58 Gyr, with negligible current star formation. The authors argue the source has no obvious jet or hotspot and is not in a galaxy cluster, and they discuss jet precession, a giant blast wave, and restarted activity as possible formation paths.

Load-bearing premise

The radial steepening claim depends on the faint outer ring being reliably detected above $3\sigma$ in the 1274 MHz, 6000 MHz, and 10,000 MHz images after they are smoothed to a common beam, but the paper reports that two of those images lost the inner structure and wing-like emission to flux loss and does not demonstrate that the periphery survives the smoothing.

Editorial extensions

If this is right

If J1218+1813 is a single physical structure, it is one of the few known circular diffuse radio sources that is securely attached to an elliptical galaxy rather than to a cluster, so its formation cannot require a cluster environment.
The steep core spectrum ($\alpha = 0.8$) and the absence of resolved jets imply the AGN is not currently feeding a young jet; the source is better described as a restarted or relic system.
The radially steepening spectral index (1.1 to 1.8) and the observed break frequency near 1.56 GHz are consistent with synchrotron aging, so the outer ring records the oldest plasma.
With a radio luminosity of $9.6 \times 10^{24}$ W Hz$^{-1}$ at 1274 MHz, the source is comparable to other recently found circular diffuse structures, making it a nearby (z $\approx$ 0.14) comparison point for odd-radio-circle formation models.
The low fractional polarization (~5%) and the wing-like secondary emission along the minor axis suggest the plasma has interacted with a turbulent or magnetically complex medium, which any formation scenario must reproduce.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

If the spectral steepening is real, the outer ring's age can be estimated from the break frequency; a spectral-age map would test whether the ring is indeed older than the inner structure, a prediction the paper's aging interpretation makes but does not directly compute.
The wing-like emission resembles the secondary lobes of X-shaped radio galaxies; an editorial extension is that the circular appearance could partly be a projection of a backflow structure rather than a spherical shell, and high-resolution rotation-measure mapping could distinguish these geometries.
The reported spectral indices of 1.1–1.6 in the inner structure are already steeper than the 0.8–1.2 range predicted by the precessing-jet simulation the paper invokes; if that simulation is the right model, the source may be older than the simulated snapshot, or the jet parameters differ.
A deep X-ray observation could look for a shock or cavity associated with a blast wave; a clean detection would support the merger/shock scenario, while a non-detection would favor a passive fossil lobe.

Share X Bluesky LinkedIn Reddit HN

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Desk Editor's Note

read the letter

J1218+1813 looks like a genuine new member of the circular-diffuse-radio-source club, and the uGMRT/VLA data are a real step up from the survey images. But the paper's headline spectral gradient—α going from ~1.1 to ~1.8 from inner to outer structure—is built on a map that the text itself undercuts. The 1274 MHz and 10 GHz images are both described as missing the extended structure, so what the map shows at the periphery needs explicit per-frequency S/N demonstration before I'd trust it.

What's new: the source was in FIRST/NVSS/TGSS but nobody had called out the circular morphology. The new observations resolve an inner structure with bent/wing-like emission plus a faint circular halo. The optical identification with an elliptical at z=0.1396 is solid. The integrated spectrum and core spectrum are standard but useful; the break frequency ~1.56 GHz is plausible. The host galaxy SED and BH mass are reasonable, though the quoted stellar-mass error of 0.011 dex looks optimistic.

Soft spots: the spectral index map is the load-bearing issue. The paper says the X-band image fails to recover the inner structure and the band-5 GMRT image missed the inner structure and wings, yet both are used at 8.8″ resolution where the extended halo is faintest. Without showing that the periphery is detected at >3σ in those two maps, the steepening to α≈1.8 is not supported. Also, Eq. (1) has a typo: it says S1400 but the text refers to S1274. The 888 MHz ASKAP flux is used without a citation. And Section 4.1 calls GMRT Band 4 "~402 MHz" when it should be 647 MHz. Those last three are minor.

Bottom line: this is a legitimate discovery paper for a rare source class. The data are real, the analysis is mostly careful, and the spectral gradient needs verification. I'd send it to review, but the referee should ask for per-frequency significance maps or a restricted spectral index map before the gradient claim can stand.

Referee Report

2 major / 4 minor

Summary. This paper reports the discovery of J1218+1813, an approximately 1-arcminute-diameter, circular diffuse radio source found in VLA FIRST data at 1400 MHz. The authors present new VLA L/C/X-band images and uGMRT band 3/4/5 images, identify an elliptical host galaxy (z = 0.139635) at the radio core, measure integrated and core radio spectra, construct a spectral index map, derive a fractional polarization from NVSS, fit the optical spectrum and SED to obtain stellar mass, age, velocity dispersion, and black hole mass, and discuss formation scenarios including jet precession, a giant blast wave, restarted activity, and ORC-like mechanisms. The main claims are that the source is a genuine ~180 kpc diffuse circular radio structure associated with the elliptical galaxy and that its spectral index steepens from ~1.1 in the inner structure to ~1.8 at the periphery.

Significance. The discovery is potentially interesting: J1218+1813 would be a rare ~180 kpc circular diffuse radio source around an elliptical galaxy, and the multiwavelength dataset (VLA C-configuration L/C/X plus uGMRT bands 3-5) is a useful addition to the small sample of ORC-like objects. The paper is strongest where it presents morphology, multi-frequency imaging, and host-galaxy characterization: the positional coincidence of the radio core with the SDSS elliptical, the deep uGMRT/VLA images, and the SED/spectroscopic analysis are concrete observational results. The headline spectral-index gradient, however, rests on a spectral index map that is not demonstrated to trace the diffuse emission at the two frequencies that the paper itself says miss extended structure; that claim needs explicit support before the formation-scenario discussion can be accepted.

major comments (2)

[3.6, Figures 2 and 7] The spectral index map (Section 3.6, Figure 7) is constructed from the 1274 MHz GMRT band 5 image, the 6000 MHz VLA C-band image, and the 10000 MHz VLA X-band image, convolved to 8.8" x 2.92" with a 3-sigma clipping threshold. Sections 3.1 and 3.2 state that the X-band image "fails to recover the prominent inner structure" and that the GMRT band 5 image "missed the inner structure and wing-like emission of the source due to loss in flux." Because the 6000 MHz image is the only one shown as contours in Figure 7, the reader cannot verify that the faint periphery is detected above 3-sigma in the 1274 MHz and 10000 MHz images after convolution. Table 2 shows that the compact core contributes only ~1-2% of the total flux at these frequencies, so if those two images recover only the core, the apparent steepening from alpha ~ 1.1 to alpha ~ 1.8 could be an artifact of comparing noise-limited residuals with different missing-flux properties. Please provide per-frequency significance maps at the common resolution (or an alpha error map) and, if necessary, derive the radial gradient from frequencies that demonstrably detect the diffuse emission (e.g., GMRT band 4 and VLA C band).
[3.5, 3.7, Table 2] The integrated spectrum and the 1274 MHz radio luminosity include the GMRT band 5 total flux (182 +/- 9 mJy) and the VLASS 3000 MHz flux (54 +/- 4 mJy), although the text says that the band 5 image suffered flux loss of the inner and wing emission (Section 3.2) and that VLASS has insufficient sensitivity for the extended diffuse structure (Section 1). These points are therefore not clearly reliable as total flux densities, and their inclusion can bias the fitted break frequency (~1.56 GHz), the spectral curvature, and the luminosity computed from Eq. (1). The authors should quantify the missing flux, replace these points with measurements from images that recover the extended structure, or explicitly treat them as lower limits rather than total flux densities.

minor comments (4)

[4.1] The sentence "combining VLA C-band data (~6000 MHz) in color scale with GMRT Band 4 in contour at ~402 MHz" is inconsistent with Table 1, where GMRT band 4 has central frequency 647 MHz; 402 MHz is band 3.
[3.7, Eq. (1)] The formula for L_rad uses S_1274 while the surrounding text refers to S_1400; the notation should be made consistent with the 1274 MHz flux density that is actually used.
[3.6] The spectral index map is described as being "between 1274 and 10000 MHz" although three frequencies were used; please clarify whether each pixel is a two-point spectral index or a linear fit to all three frequencies, and include the BRATS uncertainty map.
[Figure 8] The caption states that polarization line vectors are rotated by 90 degrees, but the text interprets the vectors as magnetic-field directions; specify whether the plotted vectors represent E-vectors or B-vectors.

Circularity Check

0 steps flagged · score 1.0 of 10

No significant circularity: the paper is an observational characterization whose derived quantities are measurements, not predictions forced by construction.

full rationale

This paper reports the discovery and multiwavelength characterization of a circular diffuse radio source. The central claims—morphology, physical size, redshift association, integrated spectral index, spectral index map, break frequency, radio luminosity, black hole mass, stellar mass and age, excitation index, and fractional polarization—are all fits or measurements obtained directly from the data. None of these quantities is used to justify its own input; for example, the integrated spectrum is fit to independent flux-density measurements at ten frequencies, and the core spectral index is fit separately to the resolved core flux densities. The spectral index map is derived from the same images that display the source, but that is a measurement procedure, not a circular derivation: there is no parameter fitted to a subset of data and then presented as an independent prediction of that same subset. Self-citations to Kumari & Pal (2024a,b) are used for qualitative comparison of spectral-index ranges and luminosities; they are not load-bearing premises and no uniqueness theorem or ansatz is imported from them. A data-quality concern remains—Sections 3.1 and 3.2 state that the VLA X-band and GMRT band 5 images missed part of the inner and wing-like emission, which could affect the reliability of the peripheral spectral indices in the spectral index map—but this is a sensitivity and calibration issue, not circularity. The derivation chain is therefore self-contained against external observations, and the appropriate finding is no significant circularity.

Assumptions & free parameters 4 free parameters · 4 assumptions · 0 invented entities

The central discovery rests on imaging and photometry, with no invented physical entities. The fitted parameters are measurements or standard SED quantities. The most consequential unstated dependency is the detectability of faint emission in the images used for the spectral index map.

free parameters (4)

Core spectral index = 0.80 ± 0.07
Fitted to core flux densities at 1274, 3000, 6000, and 10000 MHz (Table 2); used to argue the core is optically thin synchrotron emission.
Integrated spectral break frequency = ~1.56 GHz
Break in the broken power-law fit to the integrated radio spectrum (Figure 5); supports a steep-spectrum, aged source.
Average spectral index for luminosity = 1.5 ± 0.1
Taken from the spectral index map (Section 3.7) and used in Eq. (1) to compute radio luminosity; affects the quoted 9.6e24 W/Hz.
Stellar mass and age from SED = log(M*/Msun)=11.49, t_age=8.58 Gyr
Best-fit FSPS parameters; used for host galaxy characterization, not for the central radio discovery.

assumptions (4)

domain assumption The radio source lies at the spectroscopic redshift of the optical galaxy (z=0.139635).
Adopted because the radio core coincides with the optical galaxy (Section 3.3); if the association is wrong, all physical sizes and luminosities scale incorrectly.
domain assumption The M_BH - sigma* relation of McConnell & Ma (2013) is applicable.
Used in Eq. (6) to convert stellar velocity dispersion 211 km/s to black hole mass; empirical scaling relation from the literature.
standard math Planck cosmology (H0=67.4, Omega_m=0.315).
Used for luminosity distance and physical scale calculations.
standard math Flux density scale of Perley & Butler (2017).
Sets the absolute flux calibration for GMRT data; standard in radio astronomy.

how reviews work

0 comments

Cite this review

Pith. "Pith review of Circular Mystery: Exploring Diffuse Emission Surrounding a Radio Galaxy with uGMRT and VLA Multiwavelength Observations." pith.science (2026). https://pith.science/paper/7KCGGMJX

@misc{pith2026250618556,
  author       = {Pith},
  title        = {Pith review of: Circular Mystery: Exploring Diffuse Emission Surrounding a Radio Galaxy with uGMRT and VLA Multiwavelength Observations},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/7KCGGMJX}},
  note         = {Machine review of arXiv:2506.18556}
}

abstract

We report the discovery of J1218+1813, a circular diffuse radio source detected in the Very Large Array (VLA) FIRST survey at 1400 MHz. The source has an angular diameter of approximately one arcminute, corresponding to a physical size of ~180 kpc, and is associated with an elliptical galaxy with a redshift of z = 0.139635. To investigate its nature, we conducted a comprehensive multiwavelength analysis spanning both high and low radio frequencies, utilizing the VLA in C-configuration at L, C and X bands, along with the upgraded Giant Metrewave Radio Telescope (uGMRT) at bands 3 (250-500 MHz), 4 (550-850 MHz), and 5 (1000-1460 MHz). A spectral study based on these multiwavelength observations reveals that the core of J1218+1813 exhibits a steep spectral index of 0.8, indicating that the emission is dominated by optically thin synchrotron radiation. The spectral index varies between 1.1 and 1.8, from the inner to the outer structure, with the steepest values observed at the periphery of the diffuse emission. An optical analysis of the central host galaxy using spectroscopic data is also performed. The estimated black hole mass is $2.8 \pm 0.8 \times 10^{8}$ M${_\odot}$, while the host galaxy has a stellar mass of 2.9 $\times$ 10$^{11}$ M${_\odot}$ and a stellar age of 8.58 Gyr. The identification of J1218+1813 is particularly significant because it provides insight into the mechanisms responsible for the formation of circular diffuse radio structures surrounded by an elliptical galaxy. Potential formation scenarios for J1218+1813 are discussed in this paper.

Figures

Figures reproduced from arXiv: 2506.18556 by the authors.

**Figure 1.** VLA FIRST image of J1218+1813 at 1400 MHz. The contour levels are at 3σ ×(1, 1.4, 2, 2.8, 4, 4.5, 5, 5.4, 5.7, 5.8, 5.9, 6, 6.2, 6.5, 7, 7.2, 7.4), where σ = 140 µJy beam−1 is the rms noise near the background region of J1218+1813. In the left corner of the image, the synthesized beam with a resolution of 5.4′′ × 5.4 ′′ is shown. (NRAO) VLA Sky Survey (NVSS) at 1400 MHz (Condon et al. 1998) detected J1218+1813. How… view at source ↗

**Figure 2.** Upper Left: VLA C band image of J1218+1813 at 6000 MHz. Upper Right: GMRT band 4 image of J1218+1813 at 647 MHz. Lower Left: VLA X band image of J1218+1813 at 10000 MHz. Lower Right: VLA C band image of J1218+1813 at 6000 MHz overlayed with GMRT band 4 image (in contour) at the central frequency 647 MHz. The contour levels are at 3σ×(1, 1.4, 2, 2.8, 4, 5.7, 8, 11, 16, 23, 32, 40, 48, 52, 58, 64, 70, 75, 80, 90, 100)… view at source ↗

**Figure 3.** Left: GMRT band 3 image at the central frequency of 402 MHz. Right: GMRT band 5 image at the central frequency of 1274 MHz. The white ellipse in the left corner presents the synthesized beam size of the source. A B C [PITH_FULL_IMAGE:figures/full_fig_p004_3.png] view at source ↗

Figures from the paper (7 more)

**Figure 4.** Figure 4: VLA C band image of J1218+1813 at 6000 MHz overlayed with an optical image of Dark Energy Spectroscopic Instrument’s Legacy Imaging Surveys (DESI LS DR9; Schlegel et al. 2021). The contour levels are at 3σ×(1, 1.4, 2, 2.8, 4, 5.7, 8, 11, 16, 23, 26), where σ = 11 µJy b…

**Figure 5.** Figure 5: Integrated radio spectrum for J1218+1813 between 147 MHz to 10,000 MHz. C band and the angular resolution of 4.22′′ × 1.84′′ for the final image of the VLA X band. The typical rms values of the final images in the VLA C and X bands are ∼11 µJy and ∼8 µJy, respectively…

**Figure 6.** Figure 6: Integrated radio spectrum for radio core of J1218+1813 between 1274 MHz to 10,000 MHz. the inner structure. The GMRT band 4 image confirms the wing-like secondary emission along the minor axis of the source, which was seen very faintly in the VLA C band image. At the e…

**Figure 7.** Figure 7: Spectral index map of J1218+1813 between 1274 and 10,000 MHz with an angular resolution of 8.8′′ × 2.92′′ . The contour map at 6000 MHz is overlayed with the spectral index map. et al. 2013) 4 to create this spectral index map. The contour plot in [PITH_FULL_IMAGE:fig…

**Figure 8.** Figure 8: Polarized flux map in black contour overplotted with polarization line vectors (rotated by 90◦ ). The contour levels and contour peak brightnesses are shown below in the image. The inset image shows the polarized flux map in black contour overplotted with fractional p…

**Figure 9.** Figure 9: Left: The BPT diagram of previously detected ORC host galaxies along with the source (J1218+1813) presented in the current paper. The red color point represents J1218+1813. Lower right: Spectrophotometric SED of J1218+1813 using the spectrum and ugriz photometry from S…

**Figure 10.** Figure 10: Optical spectra of the host of J1218+1813, with best-fitted detected emission lines. The blue lines depict the observed spectra and the red lines represent the best-fitted spectra. II (FRII) sources are most commonly associated with winged or X-shaped radio galaxies (…

Discussion (0). Continue with ORCID to comment.

Reference graph

Works this paper leans on

109 extracted references · 68 canonical work pages

[1]

:dN DE E jV L^ M GbYW WA q ]B /<y ޻ eY 〦f* 3U1B df so S7]gYjb@@ ei o Oo +*9I ό<qX,ƬhjSQU)_xr⬕yOpN_Y:a y) =kܚ8 4 pp ( s9 hr U[ xiTXtXML:com.adobe.xmp<?xpacket begin=

thebibliography [1] 20pt to REFERENCES 6pt =0pt \@twocolumntrue 12pt -12pt 10pt plus 3pt =0pt =0pt =1pt plus 1pt =0pt =0pt -12pt =13pt plus 1pt =20pt =13pt plus 1pt \@M =10000 =-1.0em =0pt =0pt 0pt =0pt =1.0em @enumiv\@empty 10000 10000 `\.\@m \@noitemerr \@latex@warning Empty `thebibliography' environment \@ifnextchar \@reference \@latexerr Missing key o...

2017
[2]

2020, A&A, 641, 67

Aghanim, N., Akrami, Y., Ashdown, M., et al. 2020, A&A, 641, 67

2020
[3]

C., Almeida, A., et al

Ahumada, R., Allende, P. C., Almeida, A., et al. 2020, ApJS, 249, 21

2020
[4]

1980, A&A,, 85, 101

Battistini, P., Bonoli, F., Silvestro, S., et al. 1980, A&A,, 85, 101

1980
[5]

H., White, R

Becker, R. H., White, R. L., & Helfand, D. J. 1995, ApJ, 450, 559

1995
[6]

K., & Mondal, S

Bera, S., Pal, S., Sasmal, T. K., & Mondal, S. 2020, ApJS, 251, 9

2020
[7]

Best, P. N. 2004, MNRAS, 351, 70

2004
[8]

K., 2022, MNRAS, 512, 4308

Bhukta N., Pal S., Mondal S. K., 2022, MNRAS, 512, 4308

2022

Show all 109 references

[9]

D., & Königl, A

Blandford, R. D., & Königl, A. 1979, ApJ, 232, 34

1979
[10]

M., & Rawlings, S

Blundell, K. M., & Rawlings, S. 2000, AJ, 119, 1111

2000
[11]

2012, ApJ, 744, 45

Bode, T., Bogdanovi´c, T., Haas, R., et al. 2012, ApJ, 744, 45

2012
[12]

H., Fomalont, E

Bridle, A. H., Fomalont, E. B., & Cornwell, T. J. 1978, AJ, 83, 704

1978
[13]

Briggs, D. S. 1995, AAS, 27, 1444

1995
[14]

Burn, B. J. 1966, MNRAS, 133, 67

1966
[15]

Cao, D., & Wang, X. Y. 2012, ApJ, 761, 111

2012
[16]

2002, A&A, 394, 39

Capetti, A., Zamfir, S., Rossi, P., et al. 2002, A&A, 394, 39

2002
[17]

2004, PASP, 116, 138

Cappellari, M., & Emsellem, E. 2004, PASP, 116, 138

2004
[18]

2017, MNRAS, 466, 798

Cappellari, M. 2017, MNRAS, 466, 798

2017
[19]

A., Metcalfe, N., et al

Chambers, K.C., Magnier, E. A., Metcalfe, N., et al. 2019, preprint: arXiv:1612.05560

2019 arXiv
[20]

Cheung, C. C. 2007, AJ, 133, 2097

2007
[21]

2016, ApJ, 823, 102

Choi, J., Dotter, A., Conroy, C., et al. 2016, ApJ, 823, 102

2016
[22]

Coil, A.L., Perrotta, S., Rupke, D. S. N., et al. 2024, Nature, 625, 459-462

2024
[23]

J., Cotton, W

Condon, J. J., Cotton, W. D., Greisen, E. W., et al. 1998, AJ , 115, 1693

1998
[24]

E., & White M

Conroy C., Gunn J. E., & White M. 2009, ApJ, 699, 486

2009
[25]

Conroy C., & Gunn J. E. 2010, ApJ, 712, 833

2010
[26]

2020, MNRAS, 495, 1271--1283

Cotton, W.D., Thorat, K., Condon, J.J., et al. 2020, MNRAS, 495, 1271--1283

2020
[27]

H., Hardcastle, M

Croston, J. H., Hardcastle, M. J., & Birkinshaw, M. 2005, MNRAS, 357, 279

2005
[28]

M., Wright, E

Cutri, R. M., Wright, E. L., Conrow, T., et al. 2021, VizieR Online Data Catalog, II/328

2021
[29]

J., Lang, D., et al

Dey, A., Schlegel, D. J., Lang, D., et al. 2019, AJ, 157, 29pp

2019
[30]

M., Koribalski, B

Dolag, K., Boss, L. M., Koribalski, B. S., Steinwandel, U. P., & Valentini, M. 2023, ApJ, 945, 74

2023
[31]

N., & Kauffmann, G

Donoso, E., Best, P. N., & Kauffmann, G. 2009, MNRAS, 392, 617

2009
[32]

P., Duffy, P., & Komissarov, S

Downes, T. P., Duffy, P., & Komissarov, S. S. 2002, MNRAS, 332, 144

2002
[33]

T., Li A

Draine B. T., Li A. 2007, ApJ, 657, 810

2007
[34]

A., Biermann, P

Enßlin, T. A., Biermann, P. L., Klein, U., & Kohle, S. 1998, A&A, 332, 395

1998
[35]

Fabian, A. C. 2012, Annual Review of Astronomy and Astrophysics, 50, 455-489

2012
[36]

A., et al

Ferragamo, A., Barrena, R., Rubiño-Martín, J. A., et al. 2021, A&A, 655, A115

2021
[37]

2024, PASJ, 76, 765

Fujita, Y., Kawanaka, N., & Inoue, S. 2024, PASJ, 76, 765

2024
[38]

2020, Nature Astronomy, 4, 10

Gaspari, M., Tombesi, F., & Cappi, M. 2020, Nature Astronomy, 4, 10

2020
[39]

Gitti, M., Brighenti, F., & McNamara, B. R. 2012, Advances in Astronomy, 2012, 950641

2012
[40]

L., Gergely, L

Gopal-Krishna, Biermann, P. L., Gergely, L. Á & Wiita, P. J. 2012, RAA 12, 127

2012
[41]

Gopal-Krishna, & Wiita, P. J. 2000, A&A, 363, 507

2000
[42]

Hardcastle, M. J. 2018, Nature Astronomy, 2, 273

2018
[43]

J., & Croston, J

Hardcastle, M. J., & Croston, J. H. 2020, New Astronomy Reviews, 88, 101539

2020
[44]

J., & Krause, M

Hardcastle, M. J., & Krause, M. G. H. 2013, MNRAS, 430, 174

2013
[45]

J., Evans, D

Hardcastle, M. J., Evans, D. A., & Croston, J. H. 2006, MNRAS, 370, 1893

2006
[46]

E., Hughes P

Hardee, P. E., Hughes P. A., Rosen A., & Gomez E. A. 2001, ApJ, 555, 744

2001
[47]

J., Hardcastle, M

Harwood, J. J., Hardcastle, M. J., Croston, J. H., & Goodger, J. L. 2013, MNRAS, 435, 3353

2013
[48]

A., Krause, M

Horton, M. A., Krause, M. G. H., & Hardcastle, M. J. 2020, MNRAS, 499, 5765

2020
[49]

T., Jagannathan, P., Mooley, K

Intema, H. T., Jagannathan, P., Mooley, K. P., & Frail, D. A. 2017, A&A, 598, A78

2017
[50]

M., Tremonti, C., et al

Kauffmann, G., Heckman, T. M., Tremonti, C., et al. 2003, MNRAS, 346, 1055-1077

2003
[51]

R., Dennett-Thorpe, J., & Alexander, P

Kaiser, C. R., Dennett-Thorpe, J., & Alexander, P. 1997, MNRAS, 292, 723

1997
[52]

I., & Pauliny-Toth, I

Kellermann, K. I., & Pauliny-Toth, I. I. K. 1981, Annual Review of Astronomy and Astrophysics, 19, 373

1981
[53]

J., Croston, J

Konar, C., Hardcastle, M. J., Croston, J. H., & Saikia, D. J. 2012, MNRAS, 424, 1061

2012
[54]

S., Norris, R

Koribalski, B. S., Norris, R. P., Andernach, H., et al. 2021, MNRAS , 505, L11

2021
[55]

S., Khabibullin, I., Dolag, K., et al

Koribalski, B. S., Khabibullin, I., Dolag, K., et al. 2024b, MNRAS, 532, 3682
[56]

S., Veronica, A., Dolag, K., et al

Koribalski, B. S., Veronica, A., Dolag, K., et al. 2024a, MNRAS, 531, 3357
[57]

2001, MNRAS, 322, 231

Kroupa P. 2001, MNRAS, 322, 231

2001
[58]

2022, MNRAS, 514, 4290

Kumari, S., & Pal, S. 2022, MNRAS, 514, 4290

2022
[59]

2024a, MNRAS, 527, 11233

Kumari, S., & Pal, S. 2024a, MNRAS, 527, 11233
[60]

2024b, A&A, 683, A175

Kumari, S., & Pal, S. 2024b, A&A, 683, A175
[61]

J., & Horton, M

Kumari, S., Pal, S., Hardcastle, M. J., & Horton, M. A. 2024, A&A, 689, A301

2024
[62]

E., Kus, A

Kunert, M., Marecki, A., Spencer, R. E., Kus, A. J., & Niezgoda, J. 2002, A&A, 391, 47

2002
[63]

Ku\'zmicz, A., Jamrozy, M., Bronarska, K., Janda-Boczar, K., & Saikia, D. J. 2018, ApJS, 238, 9

2018
[64]

A., Chandler, C

Lacy, M., Baum, S. A., Chandler, C. J., et al. 2020, PASP, 132, 035001

2020
[65]

Laing, R. A. 1988, Nature, 331, 149

1988
[66]

A., & Bridle, A

Laing, R. A., & Bridle, A. H. 2006, MNRAS, 368, 48

2006
[67]

P., & Williams, A

Leahy, J. P., & Williams, A. G. 1984, MNRAS, 210, 929

1984
[68]

Lin, Y.-H., & Yang, H.-Y. K. 2024, ApJ, 974, 269

2024
[69]

Lochner, M., Rudnick, L., Heywood, I., Knowles, K., & Shabala, S. S. 2023, MNRAS, 520, 1439

2023
[70]

H., & Kunert-Bajraszewka, M

Marecki, A., Thomasson, P., Mack, K. H., & Kunert-Bajraszewka, M. 2006, A&A, 448, 479

2006
[71]

Marquardt D. W. 1963, SIAM, 11, 431

1963
[72]

P., Waters, B., Schiebel, D., Young, W., & Golap, K

McMullin, J. P., Waters, B., Schiebel, D., Young, W., & Golap, K. 2007, Astronomical Data Analysis Software and Systems XVI (ASP Conf. Ser. 376), ed. R. A. Shaw, F. Hill, & D. J. Bell (San Francisco, CA: ASP), 127

2007
[73]

J., & Ma C.-P

McConnell N. J., & Ma C.-P. 2013, ApJ, 764, 184

2013
[74]

2009, MNRAS, 395, 255

McConnachie, A.W., Patton, D.R., Ellison, S.L., & Simard, L. 2009, MNRAS, 395, 255

2009
[75]

R., & Nulsen, P

McNamara, B. R., & Nulsen, P. E. J. 2007, Annual Review of Astronomy and Astrophysics, 45, 117

2007
[76]

Merritt, D., & Ekers, R. D. 2002, Science, 297, 1310

2002
[77]

2019, A&A, 626, A8

Missaglia, V., Massaro, F., Capetti, A., et al. 2019, A&A, 626, A8

2019
[78]

C., & Blundell, K

Mocz, P., Fabian, A. C., & Blundell, K. M. 2011, MNRAS, 413, 1107

2011
[79]

2017, Frontiers in Astronomy and Space Sciences, 4, 42

Morganti, R. 2017, Frontiers in Astronomy and Space Sciences, 4, 42

2017
[80]

R., et al

Murgia, M., Parma, P., de Ruiter, H. R., et al. 2001, A&A, 380, 102

2001
[81]

H., et al

Murgia, M., Parma, P., Mack, K. H., et al. 2011, A&A, 526, A148

2011
[82]

Nolting, C., Ball, J., & Nguyen, T. M. 2023, ApJ, 948, 25

2023
[83]

P., Marvil, J., Collier, J

Norris, R. P., Marvil, J., Collier, J. D., et al. 2021a, PASA, 38, e046
[84]

P., Intema, H

Norris, R. P., Intema, H. T., Kapińska, A. D., et al. 2021b, PASA, 38, E003
[85]

P., Crawford, E., & Macgregor, P

Norris, R. P., Crawford, E., & Macgregor, P. 2021c, Galax, 9, 83
[86]

P., Koribalski, B

Norris, R. P., Koribalski, B. S., Hale, C. L., et al. 2025, MNRAS, 537, L42–L48

2025
[87]

O’Dea, C. P. 1998, Publications of the Astronomical Society of the Pacific, 110, 493

1998
[88]

2022, RNAAS, 6, 100

Omar, A. 2022, RNAAS, 6, 100

2022
[89]

N., Eilek, J

Owen, F. N., Eilek, J. A., & Kassim, N. E. 2014, ApJ, 794, 24

2014
[90]

Perley, R.A., & Butler, B. J. 2017, ApJS, 230, 7

2017
[91]

2019, Galaxies, 7, 70

Perucho, M. 2019, Galaxies, 7, 70

2019
[92]

2018, MNRAS, 480, 707

Prescott, M., Whittam, I.H., Jarvis, M.J., et al. 2018, MNRAS, 480, 707

2018
[93]

2021, MNRAS, 500, 1708

Ricci, R., Troja, E., Bruni, G., et al. 2021, MNRAS, 500, 1708

2021
[94]

J., & Jamrozy, M

Saikia, D. J., & Jamrozy, M. 2009, Bulletin of the Astronomical Society of India, 37, 63

2009
[95]

F., Jim \'e nez-Vicente J., Cardiel N., Cenarro A

S \'a nchez-Bl \'a zquez P., Peletier R. F., Jim \'e nez-Vicente J., Cardiel N., Cenarro A. J., Falc \'o n-Barroso J., Gorgas J., et al. 2006, MNRAS, 371, 703

2006
[96]

2009, ApJ, 695, 156

Saripalli, L., & Subrahmanyan, R. 2009, ApJ, 695, 156

2009
[97]

2022, ApJS, 259, 31

Sasmal, T.K., Bera, S., Pal, S., & Mondal, S. 2022, ApJS, 259, 31

2022
[98]

2021, AAS Meeting Abstracts, 53, 235.03

Schlegel, D., Dey, A., Herrera, D., et al. 2021, AAS Meeting Abstracts, 53, 235.03

2021
[99]

Scheuer, P. A. G. 1974, MNRAS, 166, 513

1974
[100]

S., Yates-Jones, P

Shabala, S. S., Yates-Jones, P. M., Jerrim, L. A., et al. 2024, PASA, 41, e024

2024
[101]

J., et al

Shulevski, A., Morganti, R., Harwood, J. J., et al. 2017, A&A, 600, A65

2017
[102]

Speagle J. S. 2020, MNRAS, 493, 3132

2020
[103]

K., Rao, A

Swarup, G., Ananthkrishnan, S., Kapahi, V. K., Rao, A. P., Subrahamanya, C. R., & Kulkarni, V. K. 1991, Current Science, 60, 90

1991
[104]

J., Rogers, J

Turner, R. J., Rogers, J. G., & Shabala, S. S. 2018, MNRAS, 473, 4179

2018
[105]

L., Becker, R

White, R. L., Becker, R. H., Helfand, D. J., Gregg, M. D. 1997, ApJ, 475, 479

1997
[106]

M., Birkinshaw, M., & Cameron, R

Worrall, D. M., Birkinshaw, M., & Cameron, R. A. 1995, ApJ, 449, 93

1995
[107]

L., Eisenhardt, P

Wright, E. L., Eisenhardt, P. R. M., Mainzer, A. K., et al. 2010, AJ, 140, 1868

2010
[108]

2019, ApJS, 245, 17

Yang, X., Joshi, R., Gopal-Krishna, et al. 2019, ApJS, 245, 17

2019
[109]

C., & Li, Z

Yamasaki, S., Sarkar, K. C., & Li, Z. 2024, MNRAS, 528, 3854

2024

Pith tools

Reviewed August 6, 2026 · model on record in the stance chip above.

[1] [1]

:dN DE E jV L^ M GbYW WA q ]B /<y ޻ eY 〦f* 3U1B df so S7]gYjb@@ ei o Oo +*9I ό<qX,ƬhjSQU)_xr⬕yOpN_Y:a y) =kܚ8 4 pp ( s9 hr U[ xiTXtXML:com.adobe.xmp<?xpacket begin=

thebibliography [1] 20pt to REFERENCES 6pt =0pt \@twocolumntrue 12pt -12pt 10pt plus 3pt =0pt =0pt =1pt plus 1pt =0pt =0pt -12pt =13pt plus 1pt =20pt =13pt plus 1pt \@M =10000 =-1.0em =0pt =0pt 0pt =0pt =1.0em @enumiv\@empty 10000 10000 `\.\@m \@noitemerr \@latex@warning Empty `thebibliography' environment \@ifnextchar \@reference \@latexerr Missing key o...

2017

[2] [2]

2020, A&A, 641, 67

Aghanim, N., Akrami, Y., Ashdown, M., et al. 2020, A&A, 641, 67

2020

[3] [3]

C., Almeida, A., et al

Ahumada, R., Allende, P. C., Almeida, A., et al. 2020, ApJS, 249, 21

2020

[4] [4]

1980, A&A,, 85, 101

Battistini, P., Bonoli, F., Silvestro, S., et al. 1980, A&A,, 85, 101

1980

[5] [5]

H., White, R

Becker, R. H., White, R. L., & Helfand, D. J. 1995, ApJ, 450, 559

1995

[6] [6]

K., & Mondal, S

Bera, S., Pal, S., Sasmal, T. K., & Mondal, S. 2020, ApJS, 251, 9

2020

[7] [7]

Best, P. N. 2004, MNRAS, 351, 70

2004

[8] [8]

K., 2022, MNRAS, 512, 4308

Bhukta N., Pal S., Mondal S. K., 2022, MNRAS, 512, 4308

2022