HUBBLE/COS OBSERVATIONS OF THE Lyα FOREST TOWARD THE BL Lac OBJECT 1ES 1553+113

By C. Danforth, B. Keeney, J. Stocke, J. Michael Shull, Yangsen Yao. 2010

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We present new moderate-resolution, far-ultraviolet spectra from the Hubble Space Telescope/Cosmic Origins Spectrograph (HST/COS) of the BL Lac object 1ES 1553+113 covering the wavelength range 1135 Å < λ < 1795 Å. The data show a smooth continuum with a wealth of narrow (b < 100 km s−1) absorption features arising in the interstellar medium and intergalactic medium. These features include 41 Lyα absorbers at 0 < zabs < 0.43, 14 of which are detected in multiple Lyman lines and 6 of which show absorption in one or more metal lines. We analyze a metal-rich triplet (Δcz ∼ 1000 km s−1) of Lyα absorbers at zabs ≈ 0.188 in which O vi, N v, and C iii absorption is detected. Silicon ions (Si iii, Si iv) are not detected to fairly strong upper limits and we use the measured Si iii/C iii upper limit to derive an abundance limit (C/Si) ⩾ 4(C/Si)☉ for the strongest component of the absorber complex. Galaxy redshift surveys show a number of massive galaxies at approximately the same redshift as this absorption complex, suggesting that it arises in a large-scale galaxy filament. As one of the brightest extragalactic X-ray and γ-ray sources, 1ES 1553+113 is of great interest to the high-energy astrophysics community. With no intrinsic emission or absorption features, 1ES 1553+113 has no direct redshift determination. We use intervening Lyα absorbers to place a direct limit on the redshift: zem>0.395 based on a confirmed Lyα+O vi absorber and zem>0.433 based on a single-line detection of Lyα. The current COS data are only sensitive to Lyα absorbers at z < 0.47, but we present statistical arguments that zem ≲ 0.58 (at a 1σ confidence limit) based on the non-detection of any Lyβ absorbers at z>0.4.

Subfields: Astronomy and Astrophysics, Instrumentation, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/3fac36e9812778954f5bdb9ee8e3d12679f8fd64

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Citations in the corpus

Semi-analytic modeling of the EBL and consequences for extragalactic gamma-ray spectra (2011, background): “…suggest a redshift in the range 0.3 < z < 0.4 (Treves, Falomo & Uslenghi 2007), potentially making this the most distant VHE-detected HBL. Studies of the intervening Lyα forest with Cosmic Origins Spectrograph (COS; Danforth et al. 2010) have more recently found a higher redshift bound, z > 0.395.”
Semi-analytic modelling of the extragalactic background light and consequences for extragalactic gamma-ray spectra: Modelling of the EBL and gamma-ray spectra (2012, background): “…suggest a redshift in the range 0.3 < z < 0.4 (Treves, Falomo & Uslenghi 2007), potentially making this the most distant VHE-detected HBL. Studies of the intervening Lyα forest with Cosmic Origins Spectrograph (COS; Danforth et al. 2010) have more recently found a higher redshift bound, z > 0.395.”
THE EXTRAGALACTIC BACKGROUND LIGHT, THE HUBBLE CONSTANT, AND ANOMALIES: CONCLUSIONS FROM 20 YEARS OF TeV GAMMA-RAY OBSERVATIONS (2015, background): “Danforth et al. (2010) constrained the redshift of this HBL through spectroscopic observations to z0.”
HIGH-DENSITY CIRCUMSTELLAR INTERACTION IN THE LUMINOUS TYPE IIn SN 2010jl: THE FIRST 1100 DAYS (2013, methodology): “12, and combined with the custom IDL coaddition procedure described by Danforth et al. (2010) and Shull et al. (2010).”
Quasar outflows and AGN feedback in the extreme UV: HST/COS observations of HE 0238−1904 (2013, methodology): “11f. Flat- fielding, alignment and co-addition of the processed exposures is then carried out using IDL routines developed by the COS GTO team specifically for COS FUV data1 and described in Danforth et al. (2010).”
A PANCHROMATIC VIEW OF THE RESTLESS SN 2009ip REVEALS THE EXPLOSIVE EJECTION OF A MASSIVE STAR ENVELOPE (2013, methodology): “13.6, and combined with the custom IDL co-addition procedure described by Danforth et al. (2010) and Shull et al. (2010).”