TY - JOUR
T1 - Multiwavelength monitoring of the dwarf seyfert 1 galaxy NGC 4395. I. A reverberation-based measurement of the black hole mass
AU - Peterson, Bradley M.
AU - Bentz, Misty C.
AU - Desroches, Louis Benoit
AU - Filippenko, Alexei V.
AU - Ho, Luis C.
AU - Kaspi, Shai
AU - Laor, Ari
AU - Maoz, Dan
AU - Moran, Edward C.
AU - Pogge, Richard W.
AU - Quillen, Alice C.
PY - 2005/10/20
Y1 - 2005/10/20
N2 - A reverberation-mapping program on NGC 4395, the least luminous known Seyfert 1 galaxy, undertaken with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope yields a measurement of the mass of the central black hole MBH = (3.6 ± 1.1) × 105 M ⊙. The observations consist of two visits of five orbits each, in 2004 April and July. During each of these visits, the UV continuum varied by at least 10% (rms), and only C IV λ1549 showed corresponding variations large enough to reliably determine the emission-line lag, which was measured to be of order 1 hr for both visits. The size of the C IV-emitting region is about a factor of 3 smaller than expected if the slope of the broad-line region radius-luminosity relationship is identical to that for the Hβ emission line. NGC 4395 is under-luminous even for its small black hole mass; the Eddington ratio of ∼ 1.2 × 10-3 is lower than that of any other active galactic nucleus for which a black hole mass measurement has been made by emission-line reverberation.
AB - A reverberation-mapping program on NGC 4395, the least luminous known Seyfert 1 galaxy, undertaken with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope yields a measurement of the mass of the central black hole MBH = (3.6 ± 1.1) × 105 M ⊙. The observations consist of two visits of five orbits each, in 2004 April and July. During each of these visits, the UV continuum varied by at least 10% (rms), and only C IV λ1549 showed corresponding variations large enough to reliably determine the emission-line lag, which was measured to be of order 1 hr for both visits. The size of the C IV-emitting region is about a factor of 3 smaller than expected if the slope of the broad-line region radius-luminosity relationship is identical to that for the Hβ emission line. NGC 4395 is under-luminous even for its small black hole mass; the Eddington ratio of ∼ 1.2 × 10-3 is lower than that of any other active galactic nucleus for which a black hole mass measurement has been made by emission-line reverberation.
KW - Galaxies: active
KW - Galaxies: nuclei
KW - Galaxies: seyfert
KW - Quasars: emission lines
KW - Ultraviolet: galaxies
UR - http://www.scopus.com/inward/record.url?scp=29144534895&partnerID=8YFLogxK
U2 - 10.1086/444494
DO - 10.1086/444494
M3 - ???researchoutput.researchoutputtypes.contributiontojournal.article???
AN - SCOPUS:29144534895
VL - 632
SP - 799
EP - 808
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 2 I
ER -