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| Main Authors: | , , , , , , , , , , , , , , , , |
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| Format: | Preprint |
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2025
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2510.12513 |
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| _version_ | 1866914091987107840 |
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| author | Pandey, Shivangi Rakshit, Suvendu Muneer, S. Jose, Jincen Tomar, Ashutosh Li, Yan-Rong Wang, Jian-Min Stalin, C. S. Woo, Jong-Hak Petrov, Romain G. Leftley, James Hönig, Sebastian F. Mandal, Amit Kumar Ubarhande, Tushar Wang, Shu Brotherton, Michael Gupta, Archana |
| author_facet | Pandey, Shivangi Rakshit, Suvendu Muneer, S. Jose, Jincen Tomar, Ashutosh Li, Yan-Rong Wang, Jian-Min Stalin, C. S. Woo, Jong-Hak Petrov, Romain G. Leftley, James Hönig, Sebastian F. Mandal, Amit Kumar Ubarhande, Tushar Wang, Shu Brotherton, Michael Gupta, Archana |
| contents | Robust extragalactic distance measurements are crucial for resolving the persistent discrepancy in the value of the Hubble constant (H$_0$)). Active Galactic Nuclei (AGNs), through their compact and variable broad-line regions (BLRs), enable the determination of geometric distances when reverberation mapping (RM) is combined with spectroastrometry(SA). We report results from a spectroscopic RM campaign (October 2022 to March 2023) targeting two narrow-line Seyfert 1 galaxies, Mrk 1048 and Mrk 618, using 3.6-m DOT and 2-m HCT. High-cadence spectro-photometric monitoring was carried out using onboard instruments such as ADFOSC, HFOSC, and TANSPEC, resulting in well-sampled continuum and emission line light curves. The observed fractional variability ($F_{\mathrm{var}}$) ranged from 4% to 14% across the $g$-band, H$β$, and H$α$ light curves. The time lags were measured using the interpolated cross-correlation function (ICCF), PyI$^{2}$CCF, and \textsc{JAVELIN} methods. In the rest frame, the ICCF analysis yields H$β$ lags of $10.5^{+2.6}_{-4.2}$ days for Mrk 1048 and $10.2^{+3.4}_{-2.9}$ days for Mrk 618, while the corresponding H$α$ lags are $18.7^{+5.3}_{-5.4}$ and $14.4^{+4.6}_{-10.5}$ days, respectively. The emission-line widths, measured from the rms spectra using $σ_{\mathrm{line}}$, give virial black hole mass estimates of $6.3^{+2.0}_{-2.1} \times 10^7\,M_\odot$ for Mrk 1048 and $1.2^{+0.4}_{-0.6} \times 10^7\,M_\odot$ for Mrk 618. These results will serve as a basis for absolute geometric distance calibration when combined with VLTI/GRAVITY spectro-astrometric measurements, thereby contributing to the development of AGNs as standardizable cosmological probes. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2510_12513 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Spectroscopic Reverberation Mapping for SARM: The Case of Mrk 1048 and Mrk 618 Pandey, Shivangi Rakshit, Suvendu Muneer, S. Jose, Jincen Tomar, Ashutosh Li, Yan-Rong Wang, Jian-Min Stalin, C. S. Woo, Jong-Hak Petrov, Romain G. Leftley, James Hönig, Sebastian F. Mandal, Amit Kumar Ubarhande, Tushar Wang, Shu Brotherton, Michael Gupta, Archana Astrophysics of Galaxies Robust extragalactic distance measurements are crucial for resolving the persistent discrepancy in the value of the Hubble constant (H$_0$)). Active Galactic Nuclei (AGNs), through their compact and variable broad-line regions (BLRs), enable the determination of geometric distances when reverberation mapping (RM) is combined with spectroastrometry(SA). We report results from a spectroscopic RM campaign (October 2022 to March 2023) targeting two narrow-line Seyfert 1 galaxies, Mrk 1048 and Mrk 618, using 3.6-m DOT and 2-m HCT. High-cadence spectro-photometric monitoring was carried out using onboard instruments such as ADFOSC, HFOSC, and TANSPEC, resulting in well-sampled continuum and emission line light curves. The observed fractional variability ($F_{\mathrm{var}}$) ranged from 4% to 14% across the $g$-band, H$β$, and H$α$ light curves. The time lags were measured using the interpolated cross-correlation function (ICCF), PyI$^{2}$CCF, and \textsc{JAVELIN} methods. In the rest frame, the ICCF analysis yields H$β$ lags of $10.5^{+2.6}_{-4.2}$ days for Mrk 1048 and $10.2^{+3.4}_{-2.9}$ days for Mrk 618, while the corresponding H$α$ lags are $18.7^{+5.3}_{-5.4}$ and $14.4^{+4.6}_{-10.5}$ days, respectively. The emission-line widths, measured from the rms spectra using $σ_{\mathrm{line}}$, give virial black hole mass estimates of $6.3^{+2.0}_{-2.1} \times 10^7\,M_\odot$ for Mrk 1048 and $1.2^{+0.4}_{-0.6} \times 10^7\,M_\odot$ for Mrk 618. These results will serve as a basis for absolute geometric distance calibration when combined with VLTI/GRAVITY spectro-astrometric measurements, thereby contributing to the development of AGNs as standardizable cosmological probes. |
| title | Spectroscopic Reverberation Mapping for SARM: The Case of Mrk 1048 and Mrk 618 |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2510.12513 |