Spectroscopic Reverberation Mapping for SARM: The Case of Mrk 1048 and Mrk 618

Abstract 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, enable the determination of geometric distances when reverberation mapping (RM) is combined with spectroastrometry. We report results from a spectroscopic RM campaign (2022 October–2023 March) targeting two narrow-line Seyfert 1 galaxies, Mrk 1048 and Mrk 618, using the 3.6 m Devasthal Optical Telescope and 2 m Himalayan Chandra Telescope. High-cadence spectrophotometric 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 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 JAVELIN methods. In the rest frame, the ICCF analysis yields H β lags of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>10</mml:mn> <mml:mo>.</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>5</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>4.2</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>2.6</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> days for Mrk 1048 and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>10</mml:mn> <mml:mo>.</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>2.9</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>3.4</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> days for Mrk 618, while the corresponding H α lags are <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>18</mml:mn> <mml:mo>.</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>7</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>5.4</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>5.3</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>14</mml:mn> <mml:mo>.</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>4</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>10.5</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>4.6</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> days, respectively. The emission-line widths, measured from the rms spectra using σ line , give virial black hole mass estimates of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>6</mml:mn> <mml:mo>.</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>3</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>2.1</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>2.0</mml:mn> </mml:mrow> </mml:msubsup> <mml:mo>×</mml:mo> <mml:mn>1</mml:mn> <mml:msup> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>7</mml:mn> </mml:mrow> </mml:msup> <mml:mspace width="0.25em"/> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> </mml:math> for Mrk 1048 and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>1</mml:mn> <mml:mo>.</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.6</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.4</mml:mn> </mml:mrow> </mml:msubsup> <mml:mo>×</mml:mo> <mml:mn>1</mml:mn> <mml:msup> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>7</mml:mn> </mml:mrow> </mml:msup> <mml:mspace width="0.25em"/> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> </mml:math> for Mrk 618. These results will serve as a basis for absolute geometric distance calibration when combined with VLTI/GRAVITY spectroastrometric measurements, thereby contributing to the development of AGNs as standardizable cosmological probes.

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The Astrophysical Journal
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2025-12-03
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https://doi.org/10.3847/1538-4357/ae13e3
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Galaxies: Formation, Evolution, Phenomena
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article

Spectroscopic Reverberation Mapping for SARM: The Case of Mrk 1048 and Mrk 618

Jian‐Min Wang, Jong-Hak Woo, S. Hoenig, S. Muneer et al.
The Astrophysical Journal
Galaxies: Formation, Evolution, Phenomena
article

Spectroscopic Reverberation Mapping for SARM: The Case of Mrk 1048 and Mrk 618

Jian‐Min Wang, Jong-Hak Woo, S. Hoenig, S. Muneer, R. Petrov, M. S. Brotherton, J. Leftley, C. S. Stalin, Suvendu Rakshit, Shu Wang, Amit Kumar Mandal, Archana Gupta, Shivangi Pandey, Jincen Jose, Yan-Rong Li, Tushar Ubarhande, Ashutosh Tomar
article en

Abstract

Abstract 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, enable the determination of geometric distances when reverberation mapping (RM) is combined with spectroastrometry. We report results from a spectroscopic RM campaign (2022 October–2023 March) targeting two narrow-line Seyfert 1 galaxies, Mrk 1048 and Mrk 618, using the 3.6 m Devasthal Optical Telescope and 2 m Himalayan Chandra Telescope. High-cadence spectrophotometric 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 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 JAVELIN methods. In the rest frame, the ICCF analysis yields H β lags of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>10</mml:mn> <mml:mo>.</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>5</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>4.2</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>2.6</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> days for Mrk 1048 and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>10</mml:mn> <mml:mo>.</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>2.9</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>3.4</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> days for Mrk 618, while the corresponding H α lags are <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>18</mml:mn> <mml:mo>.</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>7</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>5.4</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>5.3</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>14</mml:mn> <mml:mo>.</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>4</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>10.5</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>4.6</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> days, respectively. The emission-line widths, measured from the rms spectra using σ line , give virial black hole mass estimates of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>6</mml:mn> <mml:mo>.</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>3</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>2.1</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>2.0</mml:mn> </mml:mrow> </mml:msubsup> <mml:mo>×</mml:mo> <mml:mn>1</mml:mn> <mml:msup> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>7</mml:mn> </mml:mrow> </mml:msup> <mml:mspace width="0.25em"/> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> </mml:math> for Mrk 1048 and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>1</mml:mn> <mml:mo>.</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.6</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.4</mml:mn> </mml:mrow> </mml:msubsup> <mml:mo>×</mml:mo> <mml:mn>1</mml:mn> <mml:msup> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>7</mml:mn> </mml:mrow> </mml:msup> <mml:mspace width="0.25em"/> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⊙</mml:mo> </mml:mrow> </mml:msub> </mml:math> for Mrk 618. These results will serve as a basis for absolute geometric distance calibration when combined with VLTI/GRAVITY spectroastrometric measurements, thereby contributing to the development of AGNs as standardizable cosmological probes.

The Astrophysical JournalVol. 995(1)
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Galaxies: Formation, Evolution, Phenomena
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