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High-resolution Giant Metrewave Radio Telescope H{\sc i} 21\,cm imaging of the host galaxy of FRB\,20250316A

Balpreet Kaur, Nissim Kanekar, J. Xavier Prochaska

Abstract

We report Giant Metrewave Radio Telescope (GMRT) H{\sc i} 21\,cm imaging of NGC\,4141, the host galaxy of FRB\,20250316A at $z=0.0063$. Our GMRT H{\sc i} 21\,cm images have spatial resolutions, at $z\approx0.0063$, of $\approx0.48-8.0$~kpc, and find evidence for (i)~a companion galaxy, LEDA\,2582852, to the south-west, (ii)~a nearby (27-kpc distant) H{\sc{i}} cloud to the south-west, (iii)~disturbances in the H{\sc{i}} distributions of both NGC\,4141 and LEDA\,2582852, and (iv)~high H{\sc{i}} column densities in the south-western outskirts of NGC\,4141. A Sloan Digital Sky Survey spectrum shows evidence for a low metallicity and a high star-formation rate (SFR) surface density activity in the south-western disk of NGC\,4141, while H$α$-based SFR estimates over the last 10~Myr are higher than radio-based SFRs over the last 100~Myr. The above evidence indicates that NGC\,4141 has recently acquired metal-poor gas, via either a merger or accretion, that resulted in the south-western starburst and that may have also triggered large-scale star-formation activity in NGC\,4141, resulting in the formation of the stellar progenitor of FRB\,20250316A and the other transients. Our highest-resolution (480~pc) GMRT H{\sc{i}} 21\,cm image finds no H{\sc{i}} 21\,cm emission from the location of FRB\,20250316A or the nearby star-forming region, suggesting that most of the H{\sc{i}} here has been either ionized or converted into the molecular phase. Our non-detection of continuum emission at the location of FRB\,20250316A yields the $3σ$ upper limit $<3.2\times10^{25}$~erg~s$^{-1}$~Hz$^{-1}$, on the 1.4~GHz specific luminosity of a putative persistent radio source associated with FRB\,20250316A, one of the strongest constraints on the radio luminosity of such an associated persistent radio source.

High-resolution Giant Metrewave Radio Telescope H{\sc i} 21\,cm imaging of the host galaxy of FRB\,20250316A

Abstract

We report Giant Metrewave Radio Telescope (GMRT) H{\sc i} 21\,cm imaging of NGC\,4141, the host galaxy of FRB\,20250316A at . Our GMRT H{\sc i} 21\,cm images have spatial resolutions, at , of ~kpc, and find evidence for (i)~a companion galaxy, LEDA\,2582852, to the south-west, (ii)~a nearby (27-kpc distant) H{\sc{i}} cloud to the south-west, (iii)~disturbances in the H{\sc{i}} distributions of both NGC\,4141 and LEDA\,2582852, and (iv)~high H{\sc{i}} column densities in the south-western outskirts of NGC\,4141. A Sloan Digital Sky Survey spectrum shows evidence for a low metallicity and a high star-formation rate (SFR) surface density activity in the south-western disk of NGC\,4141, while H-based SFR estimates over the last 10~Myr are higher than radio-based SFRs over the last 100~Myr. The above evidence indicates that NGC\,4141 has recently acquired metal-poor gas, via either a merger or accretion, that resulted in the south-western starburst and that may have also triggered large-scale star-formation activity in NGC\,4141, resulting in the formation of the stellar progenitor of FRB\,20250316A and the other transients. Our highest-resolution (480~pc) GMRT H{\sc{i}} 21\,cm image finds no H{\sc{i}} 21\,cm emission from the location of FRB\,20250316A or the nearby star-forming region, suggesting that most of the H{\sc{i}} here has been either ionized or converted into the molecular phase. Our non-detection of continuum emission at the location of FRB\,20250316A yields the upper limit ~erg~s~Hz, on the 1.4~GHz specific luminosity of a putative persistent radio source associated with FRB\,20250316A, one of the strongest constraints on the radio luminosity of such an associated persistent radio source.

Paper Structure

This paper contains 4 sections, 5 figures, 3 tables.

Table of Contents

  1. Introduction
  2. Observations and Data Analysis
  3. Results and Discussion
  4. Summary

Figures (5)

  • Figure 1: Top panel: The GMRT wide-field velocity-integrated H i 21cm moment-0 image at an angular resolution of $30\farcs0$, in colourscale. Three sources are clearly visible in the image, marked as A (NGC 4141), B (a neighbouring H i cloud), and C (LEDA 2582852). The position of FRB 20250316A is indicated by the magenta star. The bottom panels show the velocity-integrated H i 21cm moment-0 images of the three objects (in contours), overlaid on the DECaLS g-band image Dey19. In each bottom panel, the lowest contour is at the $5\sigma$ H i column density sensitivity of the 300-resolution spectral cube, $3.2 \times 10^{19}$ cm$^{-2}$ per $10.4$ km s$^{-1}$ channel, with subsequent contours increasing by factors of 1.5. In all panels, the grey circle in the inset at the bottom left indicates the GMRT synthesized beam.
  • Figure 2: The GMRT H i 21cm spectra obtained from the 300-resolution spectral cube, integrating over the spatial regions identified in Fig. \ref{['fig:hi30']}. In each panel, flux density (in mJy) is plotted against barycentric velocity (in km s$^{-1}$), relative to $z = 0.0063$. Panels [A] and [C] show, respectively, the H i 21cm spectra for NGC 4141 and LEDA 2582852, both at a velocity resolution of $\approx 10.4$ km s$^{-1}$, while Panel [B] shows the H i 21cm spectrum for the south-western H i cloud, after Hanning-smoothing and resampling at a velocity resolution of $\approx 20.8$ km s$^{-1}$. The dashed blue lines indicate the $\pm1\sigma$ values for each spectrum, measured from the off-line regions.
  • Figure 3: GMRT H i 21cm velocity moment images of NGC 4141, at an angular resolution of $10\farcs0$. [A] The velocity-integrated moment-0 image, in colourscale and contours. The lowest contour is at the $3\sigma$ H i column density sensitivity of the spectral cube, $1.3 \times 10^{20}$ cm$^{-2}$ per $10.4$ km s$^{-1}$, with subsequent contours increasing in steps of $3.5 \times 10^{20}$ cm$^{-2}$ (i.e. $8\sigma$); the highest H i column density contour is at $3.2 \times 10^{21}$ cm$^{-2}$. [B] The moment-0 image of [A] (contours), overlaid on the DECaLS g-band image Dey19. [C] The H i 21cm velocity field; the velocity contours are at intervals of 15 km s$^{-1}$, with negative velocities indicated by dashed contours. [D] The H i 21cm velocity dispersion map; the contours are at intervals of 10 km s$^{-1}$. In all panels, the axes are relative to the centre of NGC 4141, with the magenta star indicating the location of FRB 20250316A, and the grey circle in the inset at the bottom left indicating the GMRT synthesized beam.
  • Figure 4: The GMRT H i 21cm moment-0 image at an angular resolution of $3\farcs0$ (contours), overlaid on the DECaLS g-band image Dey19. The axes are relative to the centre of NGC 4141, with the magenta star and diamond indicating the locations of, respectively, FRB 20250316A and the X-ray transient Sun25a. The lowest contour is at the $3\sigma$ H i column density sensitivity of the spectral cube, $9.6\times 10^{20}$ cm$^{-2}$ per 10.4 km s$^{-1}$ channel, with subsequent contours increasing by factors of 1.5, and the highest contour at an H i column density of $7.3 \times 10^{21}$ cm$^{-2}$. [B] A zoom-in on the maroon dashed square shown in [A]; the magenta plus sign indicates the location of the SDSS spectrum, shown in the bottom panel, [C]. In panels [A] and [B], the grey circle in the inset at the bottom left indicates the GMRT synthesized beam.
  • Figure 5: [A] The GALEX NUV image of NGC 4141 galex05, overlaid on the GMRT H i 21cm moment-0 image at an angular resolution of $3\farcs0$ (contours). [B] A zoom-in on the maroon dashed square shown in [A], without the H i contours. The location of the eBOSS spectrum is indicated by the arrow. It is clear that only weak NUV emission is detected at this location. In panel [A], the grey circle in the inset at the bottom left indicates the GMRT synthesized beam.