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Unraveling the Nature of HAWC J1844-034 with Fermi-LAT Data Analysis and Multi-wavelength Modeling

Sovan Boxi, Saptarshi Ghosh, Nayantara Gupta

Abstract

The extended ultra-high-energy (UHE) gamma-ray source HAWC J1844-034 is closely associated with two other sources, HAWC J1843-032 and HWC J1846-025. Moreover, other gamma-ray observatories like H.E.S.S., LHAASO, and Tibet AS$_γ$ have detected UHE gamma-ray sources whose spatial positions coincide with the position of HAWC J1844-034. The UHE gamma-ray data from several observatories help analyse the spectral features of this source in detail at TeV energies. Of the four pulsars near HAWC J1844-034, PSR J1844-0346 is closest to it and possibly supplies the cosmic-ray leptons to power this source. We have analysed the Fermi-LAT data to explore this source's morphology and identify its spectral feature in the Fermi-LAT energy band. After removing the contribution of the pulsar to the gamma-ray spectral energy distribution by pulsar phased analysis, we have obtained upper limits on the photon flux and identified the GeV counterpart PS J1844.2-0342 in the Fermi-LAT energy band with more than 5$σ$ significance, which may be a pulsar wind nebula (PWN). Finally, the multi-wavelength spectral energy distribution is modeled, assuming HAWC J1844-034 is a PWN.

Unraveling the Nature of HAWC J1844-034 with Fermi-LAT Data Analysis and Multi-wavelength Modeling

Abstract

The extended ultra-high-energy (UHE) gamma-ray source HAWC J1844-034 is closely associated with two other sources, HAWC J1843-032 and HWC J1846-025. Moreover, other gamma-ray observatories like H.E.S.S., LHAASO, and Tibet AS have detected UHE gamma-ray sources whose spatial positions coincide with the position of HAWC J1844-034. The UHE gamma-ray data from several observatories help analyse the spectral features of this source in detail at TeV energies. Of the four pulsars near HAWC J1844-034, PSR J1844-0346 is closest to it and possibly supplies the cosmic-ray leptons to power this source. We have analysed the Fermi-LAT data to explore this source's morphology and identify its spectral feature in the Fermi-LAT energy band. After removing the contribution of the pulsar to the gamma-ray spectral energy distribution by pulsar phased analysis, we have obtained upper limits on the photon flux and identified the GeV counterpart PS J1844.2-0342 in the Fermi-LAT energy band with more than 5 significance, which may be a pulsar wind nebula (PWN). Finally, the multi-wavelength spectral energy distribution is modeled, assuming HAWC J1844-034 is a PWN.
Paper Structure (8 sections, 7 equations, 5 figures)

This paper contains 8 sections, 7 equations, 5 figures.

Table of Contents

  1. Introduction
  2. HAWC J1844-034
  3. Fermi Data Analysis
  4. Standard Analysis
  5. Pulsar-phased Analysis
  6. Analysis Results
  7. PWN SED Modeling with GAMERA
  8. Discussion and Conclusion

Figures (5)

  • Figure 1: $2^{\circ}\times 2^{\circ}$ FUGIN survey molecular cloud distribution in the HAWC J$1844$-$034$ region of the integrated velocity channel from $75$-$95$ km/s investigated with $^{12}$CO($J=1{-}0$) line emission using FUGIN public data 10.1093/pasj/psx061. $1\sigma$ extension contours from H.E.S.S.HESScollab2018ana, HAWC Albert_2023, Fermi (this work), and TS-$\gamma$Tibet experiment counterparts are indicated in the left legend of the figure. LHAASO 39% extension radius measurement from LHAASO KM2A and WCDA is represented in brown and sky blue, respectively Cao_2024. Positions of PSR J1844-0346 Manchester_2005 and SNR G$28.6$-$0.1$2001PASJ...53L..21B2003ApJ...588..338U are marked in red and purple, respectively.
  • Figure 2: $\sqrt{\mathrm{TS}}$ maps from pulsar phased analysis in the full energy range considered around the HAWC J1844-034 source. (a) In the top panel, the On-phase $\sqrt{\mathrm{TS}}$ map is shown. (b) In the middle panel, the Off-phase $\sqrt{\mathrm{TS}}$ map is shown before looking for new sources through gta.find_sources() tool. (c) In the bottom panel, we show $5\sigma$ level reduction in the residuals at the position of the pulsar after modeling the new source PS J1844.2-0342. $1\sigma$ extension contours from H.E.S.S.HESScollab2018ana, HAWC Albert_2023, PS J1844.2-0342 (this work), and TS-$\gamma$Tibet experiment counterparts are indicated in the left legend of the figures. LHAASO 39% extension radius measurement from LHAASO KM2A and WCDA is represented in brown and sky blue, respectively Cao_2024. Positions of PSR J1844-0346 Manchester_2005 and SNR G$28.6$-$0.1$2001PASJ...53L..21B2003ApJ...588..338U are marked in red and purple, respectively.
  • Figure 3: SED's obtained from phased analysis of PSR J1844-0346 (a) On-phase (left panel) (b) Off-phase (right panel)
  • Figure 4: Zoomed-in $\mathrm{TS_{ext}}$ map in full energy range highlighting the extended emission around the pulsar during Off-phase. The $1\sigma$ extension of the newly identified source, PS J$1844.2$-$0342$, is marked in the figure.
  • Figure 5: Gamma-ray data from HAWC Albert_2023, LHAASO UHELHAASOCao_2024, Tibet Sudoh_2021 and H.E.S.S. HESScollab2018ana shown with Fermi-LAT upper limits obtained from our analysis. The SED obtained from our modeling is shown with a solid line.