| Canonical Name: | PKS 1440-389 |
| TeVCat Name: | TeV J1443-391 |
| Other Names: | |
| Source Type: | HBL |
| R.A.: | 14 44 00.2 (hh mm ss) |
| Dec.: | -39 08 21 (dd mm ss) |
| Gal Long: | 325.65 (deg) |
| Gal Lat: | 18.72 (deg) |
| Distance: | z=0.1385 |
| Flux: | 0.054 (Crab Units) |
| Energy Threshold: | 147 GeV |
| Spectral Index: | 3.7 |
| Extended: | No |
| Discovery Date: | 2012-04 |
| Discovered By: | H.E.S.S. |
| TeVCat SubCat: | Default Catalog |
Source Notes:
This source was moved from the Newly Announced to the Default catalogue on 200409.
The detection was announced in
ATel 4098:
- After the source was reported to be a hard, bright and steady by
Fermi, observations were carried out by H.E.S.S.: "The extrapolation
of the Fermi-LAT spectrum to very high energies (VHE; E> 100 GeV),
together with its brightness in the radio and X-ray bands, makes this
BL Lac object a good candidate for VHE emission."
More information: its H.E.S.S. source of the month
page.
Source Classification:
The source has been classified as a HSP in the
3LAC.
Positional Information:
On 12 June 2020 the source position was updated from that given
in NED to that given in
H.E.S.S. Collaboration (2020).
From
H.E.S.S. Collaboration (2020):
- R.A. (J2000): 14h 44m 0.2s +/- 2.6s (stat) +/- 1.3s (syst)
- Dec. (J2000): -39d 08' 21'' +/- 31'' (stat) +/- 20'' (syst)
* On 21 Jun 2022, a typo in the Dec. was corrected from 31'' to 21''
The coordinates from
NED:
- R.A. (J2000): 14h43m57.2s
- Dec. (J2000): -39d08m40s
Distance:
From
Zahoor et al. (2021):
- In this work, the effect of the absorption of the extragalactic
galactic background light was used to place constraints on the
redshifts of gamma-ray sources.
- "The very high energy (VHE) gamma-ray spectral indices of blazars
show strong correlation with the source redshift. Absence of any such
correlation in low energy gamma rays and X-rays indicate the presence
of Extragalactic Background Light (EBL) induced absorption of VHE
gamma rays. By employing a linear regression analysis, this
observational feature of blazars is used to constrain the redshift of
BL Lac objects which was unknown/uncertain earlier."
- Two different regression relations were used to constrain the source
redshift and the following values were found for PKS 1440-389:
- z = 0.21 +/- 0.09
- z = 0.19 +/- 0.08
From
Goldoni et al. (2021):
- In this work, BL Lac objects, selected for their potential to be TeV
emitters detectable with CTA, were observed in the optical to
constrain or measure their redshifts.
- "We performed deep medium- to high-resolution spectroscopy of 19
blazar optical counterparts with the Keck II, SALT, and ESO NTT
telescopes. We searched systematically for spectral features and, when
possible, we estimated the contribution of the host galaxy to the
total flux."
- For PKS 1440-389 a redshift of z = 0.1385 +/- 0.0005 was measured
with a median signal to noise of 230 per spectral bin in the continuum
regions.
- The authors note: "A tentative redshift of z = 0.069 has been reported
from 6dF low S/N spectroscopy (
Jones et al., 2004); we examined
the spectrum, but could not find convincing spectral features at that redshift.
Later, spectra with higher S/N (up to ∼ 80) taken by
Shaw et al., (2013)
and
Landoni et al., (2015) were featureless and could not confirm this result."
- "We were able to obtain a very high S/N EFOSC2 spectrum (S/N >= 200),
of PKS 1440−389. Careful inspection of the spectrum reveals the presence
of CaHK, CaIG, and NaID features at z = 0.1385 +/- 0.0005. We note that
at that redshift the Mgb feature of the galaxy falls into the strong
Galactic NaID absorption, and is thus undetectable. This result is
consistent with the range obtained by
Abdalla et al. (2020) within
slightly more than 2 sigma, but it contradicts the tentative redshift
published by 6dF galaxy survey."
- "The non-detection of these features in previous spectra is
consistent with their low S/N assuming a similar optical spectral
state. The host galaxy magnitude is average: M_R = -22.4 +/- 0.2."
From
H.E.S.S. Collaboration (2020):
- "An upper limit of z < 0.53 can be put on the redshift at the 95% CL
when using the EBL model of
Domínguez et al. (2011). Applying the
Franceschini et al. (2008) model yields a compatible redshift constraint. This
result significantly reduces the redshift constraint of z < 2.2
obtained through optical spectroscopy by
Shaw et al. (2013)"
From
Sahu et al. (2019):
- "Using the photohadronic model and performing a statistical analysis for different
redshifts, we constrained the redshift in the range 0.14 ≤ z ≤ 0.24."
The redshift of this object remains unknown but a tentative value of
z=0.065 from the
6dF Galaxy survey is reported in the
H.E.S.S.
ATel
From
Prokoph et al. (2015):
- "Despite many measurements in different wavelength ranges, the
redshift of PKS 1440-389 remains unknown with the currently best
constraint to be 0.14 < z < 2.2 (
Shaw et al. (2010))
Spectral Information:
From
H.E.S.S. Collaboration (2020):
- The data were fit to a power-law of the form: dN/dE = N0*(E/E0)^(-A) with ...
- A: 3.7 +/- 0.2 (stat) +/- 0.3 (syst)
- N0: 3.5 +/- 0.3 (stat) +/- 1.2 (syst) x10e-11 TeV-1 cm-2 s-1
- E0: 274 GeV
- F_int (> 147 GeV): 1.87 +/- 0.21 (stat) +/- 0.8 (syst) x10e-11 cm-2 s-1
- no evidence for a deviation from a steady flux was detected in the light curve
- the flux is reported to be 6.4% that of the Crab Nebula above 147 GeV
From
Prokoph et al. (2015):
- Spectral index: 3.61 +/- 0.34
Seen by: H.E.S.S.
-
Optical spectroscopy of blazars for the Cherenkov Telescope Array
Goldoni, P. et al., A&A 650 pA106 (2021) [LINK]
-
Very high energy gamma-ray emission from two blazars of unknown redshift and upper limits on their distance
H.E.S.S. Collaboration et al., arXiv e-prints parXiv:2004.03306 (2020) [LINK]
-
Multi-TeV Flaring from High-energy Blazars: An Evidence of the Photohadronic Process
Sahu, Sarira et al., ApJ 884 pL17 (2019) [LINK]
-
H.E.S.S. discovery of very-high-energy gamma-ray emission of PKS 1440-389
Prokoph, H. et al., ArXiv e-prints p (2015) [LINK]
-
Very high energy gamma-ray emission detected from PKS 1440-389 with H.E.S.S.
Hofmann, W., The Astronomer's Telegram 4072 p1 (2012) [LINK]
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