Unveiling a population of galaxies harboring low-mass black holes with X-rays

M. Schramm, J. D. Silverman, J. E. Greene, W. N. Brandt, B. Luo, Y. Q. Xue, P. Capak, Y. Kakazu, J. Kartaltepe, V. Mainieri

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

We report the discovery of three low-mass black hole (BH) candidates residing in the centers of low-mass galaxies at z < 0.3 in the Chandra Deep Field-South Survey. These BHs are initially identified as candidate active galactic nuclei based on their X-ray emission in deep Chandra observations. Multi-wavelength observations are used to strengthen our claim that such emission is powered by an accreting supermassive BH. While the X-ray luminosities are low at LX ∼ 1040 erg s-1 (and variable in one case), we argue that they are unlikely to be attributed to star formation based on Hα or UV fluxes. Optical spectroscopy from Keck and the VLT allows us to (1) measure accurate redshifts, (2) confirm their low stellar host mass, (3) investigate the source(s) of photo-ionization, and (4) estimate extinction. With stellar masses of M * < 3 × 109 M determined from Hubble Space Telescope/Advanced Camera for Surveys imaging, the host galaxies are among the lowest mass systems known to host actively accreting BHs. We estimate BH masses M BH ∼ 2 × 105 M based on scaling relations between BH mass and host properties for more luminous systems. In one case, a broad component of the Hα emission-line profile is detected, thus providing a virial mass estimate. BHs in such low-mass galaxies are of considerable interest as the low-redshift analogs to the seeds of the most massive BHs at high redshift which have remained largely elusive to date. Our study highlights the power of deep X-ray surveys to uncover such low-mass systems.

Original languageEnglish (US)
Article number150
JournalAstrophysical Journal
Volume773
Issue number2
DOIs
StatePublished - Aug 20 2013

Fingerprint

galaxies
x rays
stellar mass
estimates
Hubble Space Telescope
active galactic nuclei
photoionization
star formation
seeds
extinction
erg
cameras
luminosity
analogs
scaling
ionization
spectroscopy
wavelength
seed
profiles

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Schramm, M., Silverman, J. D., Greene, J. E., Brandt, W. N., Luo, B., Xue, Y. Q., ... Mainieri, V. (2013). Unveiling a population of galaxies harboring low-mass black holes with X-rays. Astrophysical Journal, 773(2), [150]. https://doi.org/10.1088/0004-637X/773/2/150
Schramm, M. ; Silverman, J. D. ; Greene, J. E. ; Brandt, W. N. ; Luo, B. ; Xue, Y. Q. ; Capak, P. ; Kakazu, Y. ; Kartaltepe, J. ; Mainieri, V. / Unveiling a population of galaxies harboring low-mass black holes with X-rays. In: Astrophysical Journal. 2013 ; Vol. 773, No. 2.
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Schramm, M, Silverman, JD, Greene, JE, Brandt, WN, Luo, B, Xue, YQ, Capak, P, Kakazu, Y, Kartaltepe, J & Mainieri, V 2013, 'Unveiling a population of galaxies harboring low-mass black holes with X-rays', Astrophysical Journal, vol. 773, no. 2, 150. https://doi.org/10.1088/0004-637X/773/2/150

Unveiling a population of galaxies harboring low-mass black holes with X-rays. / Schramm, M.; Silverman, J. D.; Greene, J. E.; Brandt, W. N.; Luo, B.; Xue, Y. Q.; Capak, P.; Kakazu, Y.; Kartaltepe, J.; Mainieri, V.

In: Astrophysical Journal, Vol. 773, No. 2, 150, 20.08.2013.

Research output: Contribution to journalArticle

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T1 - Unveiling a population of galaxies harboring low-mass black holes with X-rays

AU - Schramm, M.

AU - Silverman, J. D.

AU - Greene, J. E.

AU - Brandt, W. N.

AU - Luo, B.

AU - Xue, Y. Q.

AU - Capak, P.

AU - Kakazu, Y.

AU - Kartaltepe, J.

AU - Mainieri, V.

PY - 2013/8/20

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N2 - We report the discovery of three low-mass black hole (BH) candidates residing in the centers of low-mass galaxies at z < 0.3 in the Chandra Deep Field-South Survey. These BHs are initially identified as candidate active galactic nuclei based on their X-ray emission in deep Chandra observations. Multi-wavelength observations are used to strengthen our claim that such emission is powered by an accreting supermassive BH. While the X-ray luminosities are low at LX ∼ 1040 erg s-1 (and variable in one case), we argue that they are unlikely to be attributed to star formation based on Hα or UV fluxes. Optical spectroscopy from Keck and the VLT allows us to (1) measure accurate redshifts, (2) confirm their low stellar host mass, (3) investigate the source(s) of photo-ionization, and (4) estimate extinction. With stellar masses of M * < 3 × 109 M ⊙ determined from Hubble Space Telescope/Advanced Camera for Surveys imaging, the host galaxies are among the lowest mass systems known to host actively accreting BHs. We estimate BH masses M BH ∼ 2 × 105 M ⊙ based on scaling relations between BH mass and host properties for more luminous systems. In one case, a broad component of the Hα emission-line profile is detected, thus providing a virial mass estimate. BHs in such low-mass galaxies are of considerable interest as the low-redshift analogs to the seeds of the most massive BHs at high redshift which have remained largely elusive to date. Our study highlights the power of deep X-ray surveys to uncover such low-mass systems.

AB - We report the discovery of three low-mass black hole (BH) candidates residing in the centers of low-mass galaxies at z < 0.3 in the Chandra Deep Field-South Survey. These BHs are initially identified as candidate active galactic nuclei based on their X-ray emission in deep Chandra observations. Multi-wavelength observations are used to strengthen our claim that such emission is powered by an accreting supermassive BH. While the X-ray luminosities are low at LX ∼ 1040 erg s-1 (and variable in one case), we argue that they are unlikely to be attributed to star formation based on Hα or UV fluxes. Optical spectroscopy from Keck and the VLT allows us to (1) measure accurate redshifts, (2) confirm their low stellar host mass, (3) investigate the source(s) of photo-ionization, and (4) estimate extinction. With stellar masses of M * < 3 × 109 M ⊙ determined from Hubble Space Telescope/Advanced Camera for Surveys imaging, the host galaxies are among the lowest mass systems known to host actively accreting BHs. We estimate BH masses M BH ∼ 2 × 105 M ⊙ based on scaling relations between BH mass and host properties for more luminous systems. In one case, a broad component of the Hα emission-line profile is detected, thus providing a virial mass estimate. BHs in such low-mass galaxies are of considerable interest as the low-redshift analogs to the seeds of the most massive BHs at high redshift which have remained largely elusive to date. Our study highlights the power of deep X-ray surveys to uncover such low-mass systems.

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